This is a pre-copyedited, author-produced version of an article accepted for publication in ICES Journal of Marine Science following peer review. The version of record is available online at: https:// doi.org/10.1093/icesjms/fsz147. 1 Changes of energy fluxes in marine animal forests of the Anthropocene: factors 2 shaping the future seascape 3 4 Sergio Rossi1,2,3, Enrique Isla4, Mar Bosch-Belmar3, Giovanni Galli5, Andrea Gori1,4, 5 Michele Gristina6, Gianmarco Ingrosso1,3, Giacomo Milisenda7, Stefano Piraino1,3, 6 Lucia Rizzo7, Nadine Schubert8, Marcelo Soares2,9, Cosimo Solidoro10, Ruth H 7 Thurstan11, Núria Viladrich4, Trevor J Willis12, Patrizia Ziveri2, 13 8 1 9 Department of Biological and Environmental Sciences and Technologies, University of 10 Salento, 73100, Lecce, Italy 2 11 Institut de Ciència i Tecnologia Ambientals (UAB), Campus UAB s/n, Cerdanyola del 12 Vallés 08193, Spain 3 13 CONISMA - Consorzio Nazionale Interuniversitario per le Scienze del Mare, 00196, 14 Rome, Italy 4 15 Institut de Ciéncies del Mar (CSIC), Paseo Marítimo de la Barceloneta 39, Barcelona 16 08193, Spain 5 17 Plymouth Marine Laboratory (PML), Prospect Place, Plymouth PL1 3DH, UK 6 18 CNR-IAS, ex complesso Roosevelt, 90146 – Palermo, Italy 7 19 Stazione Zoologica Anton Dohrn di Napoli, Villa Comunale, 80121 Naples, Italy 8 20 CCMAR - Centre of Marine Sciences, University of Algarve, Campus Gambelas, 21 8005-139 Faro, Portugal 1 9 22 Instituto de Ciências do Mar-LABOMAR, Universidade Federal do Ceará, Av. da 23 Abolição, 3207, Fortaleza, Brazil 10 24 Dipartimento di Oceanografia, Istituto Nazionale di Oceanografia e di Geofisica 25 Sperimentale−OGS, Borgo Grotta Gigante, Brisciki 42/c, 34010 Sgonico – 26 Zgonik, TS, Italy 11 27 Centre for Ecology and Conservation, College of Life and Environmental Sciences, 28 University of Exeter, Penryn Campus, TR10 9FE, United Kingdom 12 29 Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, 30 Ferry Road, Eastney, PO4 9LY, UK 13 31 Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, 32 Spain. 33 34 RUNNING TITLE: Factors shaping the future animal forests 35 KEY WORDS: Benthic-pelagic coupling, climate change, water stratification, ocean 36 warming, primary productivity, secondary productivity, benthic suspension feeders, 37 energy fluxes, seston availability, heterotrophy 38 CORRESPONDING AUTHOR: Sergio Rossi, Tel. +39 0832 298853 39 Cell +39 349 0993188, sergio.rossi@unisalento.it 2 40 Abstract 41 Climate change is already transforming the seascapes of our oceans by changing the 42 energy availability and the metabolic rates of the organisms. Among the ecosystem- 43 engineering species that structure the seascape, marine animal forests (MAFs) are the 44 most widespread. These habitats, mainly composed of suspension feeding organisms, 45 provide structural complexity to the sea floor, analogous to terrestrial forests. Because 46 primary and secondary productivity is responding to different impacts, in particular to 47 the rapid ongoing environmental changes driven by climate change, the present paper 48 presents some directions about what could happen to different MAFs depending on 49 these fast changes. Climate change could modify the resistance or resilience of MAFs, 50 potentially making them more sensitive to impacts from anthropic activities (i.e. 51 fisheries and coastal management), and vice versa, direct impacts may amplify climate 52 change constraints in MAFs. Such changes will have knock-on effects on the energy 53 budgets of active and passive suspension feeding organisms, as well as on their 54 phenology, larval nutritional condition and population viability. How the future 55 seascape will be shaped by the new energy fluxes is a crucial question that has to be 56 urgently addressed to mitigate and adapt to the diverse impacts on natural systems. 3 57 Introduction 58 Marine animal forests (MAFs) (sensu Rossi et al., 2017a) acquire energy via autotrophy 59 (symbiotic algae), heterotrophy, or some combination of both (mixotrophy, Caron, 60 2016). In shallow waters, especially in the nutrient-poor tropical seas, a larger 61 proportion of the energy input to most of the scleractinians, sponges, and gorgonians 62 that comprise MAFs is provided by autotrophy. Some of these benthic suspension 63 feeders have morphological adaptations to maximize light absorption by their symbionts 64 (Enríquez et al., 2005; Brümmer et al., 2008). As depth increases, light becomes scarcer 65 and photosynthesis cannot solely provide the same metabolic support (Roth, 2014). 66 Hence, heterotrophy dominates, and is the rule in most of the MAFs that form ocean 67 seascapes below 50-60 m depth (Rossi et al., 2017b; Schubert et al., 2017). Ongoing 68 climate change is rapidly reducing the availability of both sources of energy to shallow 69 MAF (autotrophy and heterotrophy, Rossi et al., 2017b; Hughes et al., 2018a,b), and is 70 acting synergically with increasing pressures on MAFs in the Anthropocene deriving 71 from multiple anthropogenic drivers. These drivers include eutrophication, overfishing, 72 marine pollution, warming, and changes in ocean acidity (Rossi, 2013), operating at 73 multiple spatial and temporal scales. Climate change effects will act both on large 74 spatial and temperature scales (e.g. rising temperature, acidification, sea level rise), 75 chronically transforming the distribution, trophic functioning and biodiversity of 76 benthic communities; and at local scales, with punctual acute and disruptive impacts 77 (e.g. heat waves, tropical cyclones, strong storms). 78 We argue that the MAFs in our oceans are thus in a transition state, shifting from the 79 natural range of variation, found prior to the industrial revolution, to an unpredictable 80 state that may or may not stabilize during decades or centuries. 4 81 Seascape before the first transition 82 Prior to the industrial era, large areas of coastal and offshore seabed sustained complex 83 MAFs (Figure 1), mainly composed of benthic suspension feeders (Turner et al., 1999; 84 Airoldi and Beck, 2007; Harasti, 2016; Thurstan et al., 2017). Industrial bottom 85 trawling and gillnets fishing, excessive harvesting, pollution and coastal 86 mismanagement wiped out or severely reduced the structural complexity and 87 functioning of many of these MAFs, which played an essential role in biogeochemical 88 cycles (Jackson, 2001). Some of these impacts can be considered chronical and non- 89 reversible, taking into account medium and even large recovery periods, (e.g., centuries, 90 millennia), while others are reversible but with a long-lasting effect (e.g, decades). The 91 forests of the sea (both animal and vegetal) are now a remnant of what they once were, 92 with a corresponding loss of their ecosystem services (Worm et al., 2006). A very rough 93 (and probably underrated) estimate of current marine cnidarian biomass is around 0.1 Gt 94 of carbon (a very small proportion of the 550 Gt C of the overall biosphere biomass, 95 Bar-On et al., 2018). There are no historical estimates of this value, but we assume that 96 it was much higher (Thurstan et al., 2017). Consequently, their influence on the organic 97 and inorganic carbon cycles has drastically declined and, with it, their role as carbon 98 sequesters (Harvey 2004; DeVries et al. 2019). 99 Similar to the effects of agriculture and other land uses on terrestrial ecosystems, short- 100 term or episodic (pulse) disturbances can homogenize marine habitats and thus decrease 101 community complexity (Watling and Norse, 1998; Puig et al., 2012;). This is caused 102 primarily by adverse impacts on long-lived, slow reproducing, habitat-forming species, 103 which commonly form the structural component of MAF communities. For example, 104 bottom trawling in the continental shelf or in deep areas (even only a few trawls) 105 destroys soft and hard bottom assemblages which cannot recover in short-medium 5 106 elapsed times (Thrush &Dayton, 2002). In shallow coral reefs, high intensity El Niño 107 events, lasting for days or few weeks, may affect huge communities, which require 108 decades to recover recovery (Bianchi et al., 2017; Hughes et al., 2018b). Such species 109 are often unable to rapidly recover from major structural disturbances. Together with 110 the short-time scales between pulse disturbances, such as trawling, and the fact that 111 human-induced pulse disturbances tend to occur over much larger spatial scales than 112 natural pulses (Thrush & Dayton 2002), they can have disproportionally large long-term 113 effects on MAF communities. As a result of anthropogenic disturbance (e.g. the 114 Anthropocene) MAFs are evolving towards rapid cycling systems (Thrush and Dayton 115 2002; Rossi 2013), i.e. less diverse, less resilient, much younger and low-biomass 116 MAFs, with faster energy turnover processes are replacing long-lived complex 117 structures. In other words, long-lived structures are substituted by fast-growing ones 118 (such as gorgonians, polychaetes, etc., Rossi, 2013), which may be better adapted to 119 frequent disturbance (Ladd et al. 2019). As a result, having transformed nutrients 120 cycling (N, O, P, C, etc.) and carbon retention capability of these communities, we face 121 an acceleration of biogeochemical cycles. 122 Once passed this first transition, from long-lived highly complex structures to simplified 123 ecosystems, the problem will be the source of energy. Heterotrophic and autotrophic 124 inputs are already changing due to increasing sea temperatures, sea level rise (SLR), 125 extreme floods or droughts and ocean acidification, leaving serious concerns and 126 unknowns about what a second transition of the seascape will look like, or when it will 127 occur (Poloczanska et al., 2018). The relevance of MAFs may be thus higher than 128 previously thought, albeit much diminished relative to the pre-industrial age (Rossi et 129 al., 2017a). 130 6 131 Facing the second transition 132 At the time of writing, Mauna Loa Observatory in Hawaii has registered a CO2 133 concentration above 410 ppm (IPCC, 2018), far surpassing critical limits for coral reefs 134 put forward only 10 years ago (Veron et al., 2009). The earth system transformation or 135 time reduction of biogeochemical responses due to climate change is happening (fast 136 changing environmental conditions) (Reay et al., 2008), and part of the long-lived 137 structures (terrestrial and/or marine) that may partially mitigate their effects (as natural 138 carbon sinks) are strongly diminished or missing. The shift in ecosystem functioning is 139 thus continuing, but now MAFs have another problem that was not present during the 140 first transition: the acquisition of energy. 141 Most tropical coral reefs depend on light harvesting (autotrophy) are suffering from 142 recurrent bleaching due to sea temperature rises and episodic heatwaves, impacting their 143 symbiotic algae living in the tissues (Hoegh-Guldberg et al., 2018; Hughes et al., 144 2018a). Mortality of habitat-forming symbiotic corals results in the degradation of 145 formerly complex and highly biodiverse ecosystems, with a concomitant loss of 146 functionality. Scleractinian corals are being replaced by macroalgae, octocorals, 147 zoanthids or sponges (Norström et al., 2009; Bell et al., 2013; Cruz et al., 2016) that 148 have the advantage of being more flexible in their trophic strategies (switching from 149 autotrophy to heterotrophy, depending on the environmental conditions, Fabricius et al., 150 1995; Rossi et al., 2018). The synergistic effects of multiple stressors (Figure 2) in a 151 rapidly changing environment make the energetic performance of the autotrophy- 152 dependent anthozoans sub-optimal, and may threaten their dominance and survival 153 (Ruzicka et al., 2013). We thus appear to be facing the transformation of one of the 154 most biodiverse and complex systems that has ever existed on Earth (Hughes et al., 155 2017a,b). It is unlikely that these habitats will recover their past biodiversity and 7 156 structure should conditions stabilize. The problems related with light harvesting and 157 temperature shifts may be, however, an opening for opportunists and alien or 158 “immigrant” species that thrive in the new conditions. In a global-change context, due 159 to perturbations, such as bio invasions (Libralato et al., 2015; Rizzo et al., 2017), 160 eutrophication (Cloern, 2001) and ocean warming (Churst et al., 2014), plankton 161 communities might respond differently and their production could have different fates at 162 higher trophic levels (D’Alelio et al., 2016). In the Mediterranean Sea (an area highly 163 impacted by tropicalization trends, Bianchi, 2007), tropical alien scleractinians and soft 164 corals may effectively reproduce (thus producing viable new recruits) in a warmer and 165 more transparent sea. These tropical organisms may be benefited from the new 166 conditions related to the climate change. At the same time, these conditions may induce 167 latitudinal shifts in the distribution of those species that may effectively migrate on time 168 (Bianchi 2007). 169 SLR is expected to increase coastal erosion, mixing and circulation, and hence, increase 170 turbidity due to the amount of suspended sediment. This will decrease light availability 171 for photosynthesis and increase sediment-induced stress (Storlazzi et al., 2011) in 172 MAFs composed of mostly symbiotic corals. Thus, SLR undermines the corals’ ability 173 to grow and thrive in future seascapes of drowned reefs. Consequently, many 174 scleractinians will be unable to grow fast enough to keep up with predicted SLR, 175 leaving tropical coasts and some oceanic islands exposed to increasing erosion and 176 flooding risk. Only a few reefs will have the capacity to track SLR projections under 177 futures scenarios of climate change by 2100 (Perry et al., 2018), leaving tropical coasts 178 and some oceanic islands exposed to increasing erosion and flooding risk. 179 But climate change will impact MAFs far beyond the surface layers: the transformation 180 of primary and secondary productivity patterns (microphytoplankton, zooplankton and 8 181 seaweeds/seagrasses). MAFs depend on this production as filter feeders (Rossi et al., 182 2017b). All the ongoing transformation of our oceans due to climate change will affect 183 food availability, the MAFs capability to capture particles, retain the associated energy 184 and invest it in new recruits. For example, ocean warming will potentially result in 185 longer periods of water column stratification; thus, affecting primary productivity, 186 diurnal plankton migrations and possibly leading to discontinuities in prey availability 187 for MAFs (Doney, 2006). Also, a slowdown in water circulation and reduced upwelling 188 due to freshwater input at higher latitudes in the North Atlantic is expected (Curry et al., 189 2003). We are still trying to understand how will the general and local patterns of ocean 190 circulation change, being the current models clearly uncertain in several areas and 191 showing spatially heterogeneous trends (e.g.,. the Mediterranean sea, Adloff et al., 192 2015). We must consider that MAFs will be largely impacted by these future changes. 193 Since MAF-forming organisms are sessile, they depend on currents and sinking 194 biogenic particles to feed that are expected to be drastically reduced by increased ocean 195 stratification. Thus, the potential reduction in plankton production in the surface (i.e., 196 Steinacher et al., 2010; Bopp et al., 2013), accompanied by a reduced export flux of 197 particulate organic carbon to the deep sea (Jones et al., 2014), will have severe impacts 198 on MAFs. This will come together with increased nutritional requirements to buffer 199 negative effects of ocean acidification and increased temperatures (Edmunds, 2011; 200 Castillo et al., 2014; Towle et al., 2015; Büscher et al., 2017). 201 In recent decades, overall phytoplankton productivity has already declined in response 202 to climate change, with seasonal shifts observed in several areas (Henson et al., 2013; 203 Laufkötter et al., 2015; D’Alelio et al., 2016). Also, changes in bloom formation (much 204 earlier and persistent in some cases), species dominance and total biomass size have 205 been described in different areas. Phytoplankton growth depends on temperature and the 9 206 availability of light and nutrients, including nitrogen, phosphorus, silicon and iron. In 207 more stratified waters, especially those of tropical and subtropical systems (including 208 the warm temperate seas), higher temperatures may assist phytoplankton growth, but 209 nutrient availability will be limited by a lack of mixing. Furthermore, the temperature- 210 driven increase in primary productivity might be more than compensated by an increase 211 in respiration and catabolism, with net results of increased dissolved organic and 212 inorganic matter, rather than biomass (Lazzari et al., 2014). The loss of productivity in 213 these tropical and subtropical areas is expected to be offset by a higher productivity 214 poleward. A slight decrease in annual primary production of 0.4% (0.10 Pg C year-1 of 215 an ocean average of 50 Pg C year-1) might result in similar C preservation, and an 216 unknown quantity of C sunk, sedimented or available for MAFs (Keil, 2017). Taking 217 into account that models estimated declines of up to 20% of the productivity in some 218 regions during the next 60 years (Roxy et al., 2016) the effect on MAFs could be 219 dramatic. 220 Other effects may be related to salinity change. The increasing salinity of the 221 Mediterranean Sea, for example, particularly in the intermediate and deep layers, is 222 related to the general increases in seawater temperature and evaporation rates in this 223 basin (Rixen et al., 2005; Vargas-Yáñez et al., 2010; Borghini et al., 2014). This 224 process is accelerated by decreases in river flow to the sea due to the construction of 225 water reservoirs (Vargas-Yáñez et al., 2017) and decreased precipitation (Viola et al., 226 2016). Changes in salinity are critical for ocean mixing depth and current circulation, 227 and therefore for the dynamics of nutrient transfer. Such changes can alter the structure 228 of the communities of planktonic primary producers and the trophic chains that feed on 229 them (Learmonth et al., 2006). Although this process may be spatially heterogeneous 230 (Adloff et al. 2017), changes in salinity and density are critical or ocean mixed layer 10 231 depth and thermohaline circulation, therefore for the dynamics of nutrient transfer and 232 spatial connectivity. Circulation dynamics are also affected by warming-induced 233 stronger stratification, changes in the winter mixing layer depth and a poleward 234 displacement. Another example can be deduced for the North Atlantic general 235 circulation pattern. Since the mid-twentieth century, a weakening of the Atlantic Ocean 236 overturning circulation has been detected (Caesar et al.,. 2018). This change has a major 237 impact on climate but might also reduce the deep oxygen concentrations and the energy 238 supply (in terms of nutrients and organic matter flux) into the deep ocean, with 239 unpredictable biological consequence benthic marine ecosystems. 240 One of the least investigated factors is the effect of change in rainfall patterns on MAFs, 241 especially in the animal-dominated coastal seascapes. Rainfall commonly controls the 242 estuarine water flow processes and the transfer of materials (nutrients and organic 243 matter) from the mainland to the sea. The Intergovernmental Panel on Climate Change 244 (IPCC, 2018) is expecting shifts in the pattern of rainfall worldwide, including reduced 245 rainfall and intense droughts in some regions, while in others increases in precipitation 246 and floods are predicted. Reduced rainfall and extreme droughts will decrease the 247 fluvial contribution to the ocean and affect the input of carbon for sessile suspension 248 feeders, composing the coastal MAFs. 249 Climate change appears to be altering also the productivity of macroalgae and 250 seagrasses, which has consequences for the availability of plant detritus. Unsworth et al. 251 (2008) suggested that the primary productivity of seagrass meadows has already 252 diminished, so the available detritus has declined (Maxwell et al., 2017). Warming and 253 ocean acidification will continue to affect macroalgal productivity in different ways 254 (e.g., decrease in calcification rates in coralline algae, increased biomass in fleshy algae; 255 Comeau and Cornwall, 2017; Duarte et al., 2018). Calculations show that for some 11 256 suspension feeding organisms detritus may represent more than 50-90% of their food 257 inputs (Gili and Coma, 1998), though it represents a low-quality food source (Rossi and 258 Gili, 2009). Changes in its availability may be a key to understand which suspension 259 feeding organisms will be affected by such detritus flux change. 260 Greenhouse gas–driven ocean warming is also lowering the oxygen concentrations in 261 both the open ocean and coastal waters, with negative consequences in the distribution 262 and abundance of animal populations and associated biogeochemical cycles (Breitburg 263 et al., 2018). As oxygen depletion becomes more severe, persistent and widespread, a 264 greater fraction of the ocean is losing its ability to support high-biomass and diverse 265 animal assemblages. Warming also raises metabolic rates, thus accelerating the rate of 266 oxygen consumption. Therefore, decomposition of sinking particles occurs faster and 267 their remineralization shifts toward shallower depths (Brewer et al., 2017). Under such 268 conditions, energy is recycled faster. Changes of the microbial loop also affect marine 269 food webs and hence, the efficiency of organic carbon transfer (Howes et al., 2015; Keil 270 et al., 2016). Guidi et al. (2016) suggest that specific plankton communities, from the 271 surface and deep chlorophyll maximum, correlate with carbon export at 150 m depth. 272 Thus, changes in the microbial loop and the degradation speed of organic matter will 273 synergistically affect deep MAFs. 274 Pelagic secondary production also suffers climate change-related impacts, either directly 275 through changes in the environmental conditions or indirectly through changes in 276 phytoplankton productivity (Howes et al., 2015), and trophic efficiency of pelagic food 277 webs (Fanelli et al. 2013). Zooplankton occupies a key position in marine ecosystems, 278 serving as the primary trophic pathway for the transfer of primary productivity to higher 279 trophic levels. Given that zooplankton is an important food source for sessile filter 280 feeders (Gili & Coma, 1998) and that it drives carbon transfer to benthic habitats, 12 281 changes in these communities would have significant impacts on the benthic seascapes 282 due to shifts in benthic-pelagic coupling (Griffiths et al., 2017). Overall, zooplankton 283 communities are predicted to shift toward dominance by smaller-sized individuals 284 (microozooplankton) and to alter dominance patterns in favor of species with lower 285 metabolic demands, in response to global warming and stratification of waters 286 (Richardson and Schoeman, 2004; Daufresne et al., 2009). Pelagic secondary 287 production is already changing in temperate coastal areas (Smetacek and Cloern, 2008), 288 affecting the potential quality of food transferred to other organisms. It is likely that a 289 change in the size distribution within zooplankton communities, stimulated by increases 290 in sea surface temperature, as well as shifts in their prey availability and composition, 291 will cause ecosystem shifts in MAFs. These shifts will trigger changes in energy fluxes 292 related to the MAFs due to the potential transformation of the available food, as 293 observed for deep waters (Fanelli et al. 2013). In fact, resource availability more than 294 hydrographic conditions seems to explain the assemblage variation of benthic fauna in 295 certain areas (Fanelli et al.,. 2013). 296 Further, climate change impacts work synergistically with other disturbances reducing 297 the availability of food for suspension feeders (Kunhz et al., 2014; Yesson et al., 2016). 298 For example, trawled sediments at 500 m depth are characterized by a significant 299 decrease (5–52%) in labile organic matter content, reduction in the organic C turnover 300 rates and by a significant reduction in meiofaunal abundance, biomass and biodiversity 301 (Pusceddu et al., 2014). Loss of these deep habitats would lead to decline or 302 disappearance of the enduring animal forests and their ecosystem services, but also their 303 role as an essential part of the biogeochemical cycles. In general, the future soft bottoms 304 are expected to favor smaller benthic organisms, lowering the energy transfer and 305 sediment mixing (Keil, 2017). Adding both direct and indirect impacts will cause 13 306 negative feedback on MAFs, particularly for suspension feeders especially sensitive to 307 cumulative impacts. 308 The impact of changing C fluxes on the energetic budget of MAFs 309 Let us discuss some examples of what could be the questions to be addressed in such 310 future seascape panorama. Lowering the water column productivity in the tropical and 311 subtropical zone, and conditioning the Symbiodinium host to other than scleractinian 312 species in many areas, what will be the future of the seascape in coral reefs? Which 313 suspension feeding species could substitute the efficient light harvesting scleractinians? 314 Bell et al. (2013) suggest that sponges may become the dominant organisms inhabiting 315 some tropical shallow-water reefs when the effect of global climate change and ocean 316 acidification becomes established. Sponges, gorgonians and scleractinian corals are 317 major components of MAFs and respond differently to a fast-changing marine 318 environment (Figure 3). For example, direct and indirect responses of the sponge 319 holobiont (Roughgarden et al., 2018) and its constituent parts (host and symbionts) to 320 changes in temperature and pH are generally less extreme than the effects of these 321 factors on a coral holobiont. Overall, the predicted shifts in the Anthropocene (decrease 322 of pH, increase of turbidity and sedimentation in coastal waters, increase of seawater 323 temperature) favors heterotrophic sponges instead of mixotrophic scleractinian corals. 324 Whilst sponges have already increased in abundance as sensitive corals have declined in 325 the Caribbean, Atlantic and Indo-Pacific (Bell et al., 2013), soft corals are also 326 becoming more abundant in certain areas (Ruzicka et al., 2013; Lenz et al., 2015; 327 Schubert et al., 2017). The flexibility of autotrophic versus heterotrophic contributions 328 to the host’s energy budget may be a key to understand why they are becoming 329 dominant under certain circumstances (Fabricius et al., 1995; Rambsy et al., 2014; 330 Schubert et al., 2017; Rossi et al., 2018). However, some tropical shallow-water reefs, 14 331 dominated by stress-tolerant corals, may be more resilient to global environmental 332 change. This occurs where the temperatures are naturally elevated and/or environmental 333 conditions are historically suboptimal (e.g., through high turbidity or sedimentation). 334 These natural features provide an “environmental filter” potentially liable to harbor 335 thermal-resistant taxa and disturbance-tolerant corals (Sanders and Baron-Szabo, 2005; 336 Morgan et al., 2016). 337 At greater depths we find the mesophotic ecosystems – (MEs, 30-150 m depth). These 338 are diverse benthic ecosystems that occur generally along the continental shelves, 339 seamounts and oceanic islands (Khang et al., 2017). The MEs are composed of a mosaic 340 of distinct seascapes and may be dominated by algae (rhodolith beds or coralline algal 341 reefs) and/or sessile suspension feeders. These seascapes include MAFs, such as 342 scleractinian-dominated ecosystems (deep coral reefs), sponge grounds, octocoral, and 343 black coral forests (Soares et al., 2019). MEs will be affected by many of the same 344 changes in energy fluxes due to local and global human stressors, as experienced by 345 shallow communities (Rocha et al., 2018; Soares et al., 2019). However, these deeper 346 ecosystems (especially in the lower mesophotic zone, 70-150 m depth) are more 347 dependent on the heterotrophic input than their shallow-water counterparts (Houlbréque 348 and Ferrier-Pagés, 2009). 349 Although these systems will not be directly affected by changing light levels, 350 temperature increase is a possible scenario in these systems, and a global average 351 warming of 1°C change may be a real constraint for the productivity of these systems in 352 a near future (Khang et al., 2017). This assumption, however, is region-dependent. 353 Some areas of the planet have well-mixed water columns, where higher sea surface 354 temperatures can reach down to 60 m depth. At this depth, MEs are still dominated by 355 mixotrophic scleractinian corals (Sinniger et al., 2013) that may be less resilient than 15 356 shallow reefs, considering the increase of multiple human impacts (Rocha et al., 2018; 357 Soares et al., 2019), combined with being vulnerable due to slow growth rates, limited 358 genetic connectivity, and low reproductive performance (Shlesinger et al., 2018). 359 Heterotrophic taxa (i.e., non-symbiotic corals, octocorals, sponges, and black corals) are 360 more common in the deeper zone (70-150 m depth) (Semmler et al. 2017). The benthic 361 species in this zone will be affected by changes in the carbon export (from primary and 362 secondary productivity) to the sea floor. We hypothesize that shifts in energy fluxes will 363 significantly affect the health status of mesophotic species depending on the ecoregion 364 and the species bathymetric distribution. Moreover, the effects will be most likely 365 species-specific, considering the different strategies of carbon budget management 366 among sessile suspension feeders. 367 In deeper areas, where a high proportion of the biomass of MAFs is concentrated (e.g., 368 submarine canyons, paleochannels, sea mountains, cold water coral reefs, Henry et al., 369 2017), the particulate flux could decrease in some areas by up to 55% (Sweetman et al., 370 2017), probably altering 80% of the communities. In deep areas, were the particulate 371 organic carbon flux may be limited (POC flux 1-2 g C m-2 year-1; Watling et al., 2013), 372 a reduction of available organic matter may be critical for respiration, reproduction, 373 growth and other metabolic pathways of the species. Cold water corals will be exposed 374 to changes in currents and surface productivity, as well as oxygen impoverishment and 375 pH changes (Sweetman et al., 2017). For example, it has been suggested that in areas 376 like the Northern Adriatic Sea and the Gulf of Lions (Mediterranean Sea), dry-extreme 377 cold winds (the main driver of cold water cascade, bringing sediments, oxygen and food 378 to the MAFs) may be reduced, producing a direct effect on the viability of deep water 379 populations (Taviani et al., 2016; De Clippele et al. 2018). Hypoxia can also have 380 dramatic consequences for their metabolism, altering the input-output equilibrium, 16 381 which will be reflected in their survivorship (Gooday et al., 2010). Biodiversity declines 382 as O2 declines, but also as food availability gets scarcer and thus, the basic maintenance 383 of the structuring organisms is no longer given due to the imbalances in energy inputs- 384 outputs (Rossi et al., 2017b). This scenario is a real possibility in deep seas all over the 385 world, but the mechanisms involved are not yet well understood (Sweetman et al., 386 2017). 387 Another example of potential repercussions of changes in energy fluxes in MAFs exists 388 in the warm temperate seas. The Mediterranean Sea is possibly one of the clearest 389 examples of drastic and rapid changing seascapes in shallow waters. Recent mass 390 mortalities, affecting suspension-feeding organisms, occurred due to anomalous high 391 sea surface temperatures and water stratification (Garrabou et al., 2009). However, the 392 centre of the problem may be the lack of an adequate trade-off between food input and 393 energetic costs for metabolic maintenance (Rossi et al., 2006; Galli et al., 2016). 394 Changes in the timing of peaks in primary productivity at key moments may limit the 395 capacity of MAFs to store energy, after which they may then face prolonged warm 396 conditions in non-optimal conditions (e.g., long water mass stratification periods in 397 summer, Rossi et al., 2006). The lack of an adequate lipid storage, gathered in the 398 normally productive late winter-early spring period, may be crucial to explain mass 399 mortality events (Rossi et al., 2017b). Moreover, extreme events, such as frequent and 400 prolonged heat waves, may impact the survival of low-motility organisms, favouring the 401 transformation of marine snow in marine mucilage, but also triggering selective 402 zooplankton mortality, which diminishes the carbon availability for suspension feeding 403 animals (Danovaro et al., 2008; Marbà et al.,. 2015). It might be noted that recent 404 studies highlight how in the near future marine heat waves will be more frequent, more 405 severe and reaching deeper layers in the water column (Galli et al., 2017). 17 406 Nutritional condition and recruitment: a key factor to understand future seascapes 407 Climate change and particularly temperature can deeply influence organisms’ 408 metabolism. Reproduction, considered as one of the keys factors to understand the 409 distribution and resistance of species in the face of environmental change (Adjeroud et 410 al., 2017), would be one of the most affected processes. Reproductive events and 411 success are related not only to temperature, but also to the available autotrophic or 412 heterotrophic inputs (Rossi et al., 2017b). Changes in temperature, primary productivity 413 and water stratification, due to the ocean warming, are thus affecting trophic chains in 414 sensitive world areas (Milisenda et al., 2017; Rossi et al., 2017b), inducing a mismatch 415 between functional groups and trophic levels (Edwards and Richardson, 2004). Energy 416 storage, essential for the offspring viability (and concentrated in high-productive 417 seasons), may be slightly changing (Rossi et al., 2017b). The lack of food affects 418 directly the number of eggs or larvae produced (Gori et al., 2013), being a potential 419 factor to be considered in the general understanding of seascape changes. We know that 420 larval growth rates can increase associated to faster metabolic activity (Munday et al.,. 421 2009), which depends on the amount of energy stored in the offspring. The source of 422 this energy is the mother colony or individual that will invest such macromolecules 423 depending to the availability of the organic matter (Rossi et al.,. 2017b). 424 Phenology of the species (i.e. the timing of key seasonal events) will also affect the 425 viability of new generations (Rossi et al., 2019). In fact, more than 60% of studied 426 species in aquatic systems have responded to ocean warming by advancing their 427 reproductive phenology (Greve et al., 2005; Poloczanska et al., 2018). Since 428 reproductive events have evolved to occur at optimal times of food availability to 429 maximize the survival of the next generation (Forrest and Miller-Rushing, 2010; Rossi 430 et al., 2019), these phenological shifts can reduce reproductive success of species and 18 431 affect their population in the long-term (Schaper et al., 2012). As an example, spawning 432 and release of larvae in summer implies that lecithotrophic larvae of anthozoans in the 433 Mediterranean Sea settle and metamorphose a few weeks before phytoplankton 434 concentration rises in the early fall (Rossi and Gili, 2009), supplying moderate to high 435 amounts of food. Within the context of global change (see the previous considerations), 436 there is a risk that the period of trophic crisis (Rossi et al.,. 2006) might be significantly 437 prolonged to the point that the capacity of the energy reserves in lecithotrophic larvae 438 would not last until the arrival of favorable feeding conditions in the early autumn. This 439 situation could be even worse if the spawning of these species would be triggered earlier 440 by the increase of in temperature (Rossi et al., 2019). Despite the potential severe 441 consequences of the undermining of reproductive success for the long-term persistence 442 of species populations, little is known of the importance of prey phenology to 443 population persistence. This lack of studies on benthic suspension feeders in the 444 literature is especially problematic not only due to their ecological importance, but also 445 because research suggests that shifts in phenology will occur faster in marine 446 environments (4.4 days per decade) than in terrestrial ecosystems (2.3–2.8 days per 447 decade) (Parmesan, 2007; Poloczanska et al., 2018). 448 Larval nutritional condition and species phenology will affect the potential seascape 449 composition in a near future, (e.g., decades), but population connectivity has to be also 450 considered from another point of view: hydrodynamic features and larval dispersal 451 (Andrello et al.,. 2015). As previously explained, climate change will modify water 452 current velocity patterns, which could affect the dispersal routes of larvae and 453 connectivity (Brochier et al.,. 2013). In a recent study, Andrello et al. (2015) suggested 454 that larval dispersal distances in the Mediterranean Sea may decrease by 10%, thus 455 increasing by 5% the retention effect Sea. This is important because it implies a higher 19 456 concentration of larvae in smaller areas and a significant decrease in connectivity in 457 certain areas and periods (Andrello et al.,. 2015). A decrease in larval dispersal 458 distances and a higher retention in certain areas would probably decrease the gene flow 459 (Watson et al.,. 2011), affecting also the viability of the MAF populations. 460 The ability to transform the energy input into viable offspring, the hydrological 461 conditions that will change connectivity, and the phenological changes in prey life 462 cycles and reproductive timing of MAF species are important knowledge gaps that 463 demand prioritization, if we want to foresee the consequences of the ongoing seascape 464 transformation. 465 Conclusion: Seascape future depends on the first and second transition 466 It is clear that changes in the autotrophic or heterotrophic inputs of suspension feeding 467 organisms due to climate shifts will partly set the future seascape due to a complex 468 balance in which “winners” and “losers” will be identified (Berggren et al., 2009). The 469 first transition (the degradation or loss of complex benthic structures, currently 470 underway; Jackson, 2001) is likely to accelerate a second transition (the potential 471 change in quantity, quality and timing of food availability, related mainly to climate 472 change effects) due to the time reduction of biogeochemical cycles. The biogeochemical 473 cycles will speed the change between “trophic cages”, and the lack of long-lived 474 organisms will accelerate this rushed “loop”. These changes are having and will have 475 dramatic influences on the distribution and composition of the communities populating 476 the seafloor and thus should be considered in the conservation decision-making 477 processes. In fact, the criteria to protect specific areas has to consider all the above 478 mentioned factors shaping the future seascape. Minimizing the anthropogenic pressure 479 on biodiversity (Coll et al.,. 2012) and considering the functional ecology of the MAF 20 480 species (Rossi et al.,. 2017a) will be the key to preserve the ecosystem services of such 481 complex habitat-forming organisms. 482 Changes in the MAFs will alter the capability to store carbon (sequestration), which has 483 already diminished (Arias-Ortiz et al., 2018; Steffen et al., 2018). The acceleration of 484 biogeochemical cycles will act as a positive feedback and increase to a certain point in 485 which the dominant species will reach a new equilibrium. Thus, the approximately 30% 486 of greenhouse atmospheric carbon removed by the oceans (Le Quere et al., 2013) would 487 partly remain, as previously explained, in fast cycling ecosystem functioning. Looking 488 at this panorama, it seems urgent to identify which ecosystem services are directly 489 affected by the climate change impacts on MAFs. So far, only new technology 490 (especially ROVs, AUVs and landers) will help to better understand such processes, 491 providing quantitative data from shallow to deep waters. This technology is now 492 cheaper and easier to handle and facilitate the essential map the oceanic floors that are 493 so far, only projected in general models that lack actual quantitative data (Halpern et 494 al.,. 2015). 495 Many questions are still open and need to be addressed in the near future: Which 496 organisms will be more affected, passive or active suspension feeders? Will the 497 autotrophic component increase or decrease? Will climate change favour species that 498 are less capable to store carbon in their structures? And more intriguing: how long will 499 this transition phase take? 500 In general, all these questions and the above-mentioned thoughts are essential to push 501 administrations towards a stronger commitment to the protection and restoration of the 502 oceans’ marine benthos. It is not only a biodiversity and fisheries issue. The marine 503 animal forest conservation is a key point for ocean health, as it may be part of the 21 504 solution to mitigate the greenhouse gas problems of the planet because represents a 505 carbon sink complex structure. 506 507 Acknowledgements 508 The authors want to thank Euromarine network for the opportunity to create the 509 working group ANFORE. We also thank the Marie Curie International Outgoing 510 Fellowship project ANIMAL FOREST HEALTH (Grant Agreement Number 327845). 511 This work contributes to the ICTA “Unit of Excellence” (MinECo, MDM2015-0552). 512 Alberto Gennari is kindly acknowledged for the fig. 2 artwork. 513 514 References 515 1. Adjeroud, M., Kayal, M. & Penin, L. (2017). Importance of recruitment 516 processes in the dynamics and resilience of coral reef assemblages. In: Marine 517 Animal Forests: the ecology of benthic biodiversity hotspots. Eds. Rossi S, 518 Bramanti L, Gori A, Orejas C. Springer, Germany, pp. 549-570. 519 2. Adloff, F., Somot, S., Sevault, F., Jordà, G., Aznar, R., Déqué, M., et al. (2015). 520 Mediterranean Sea response to climate change in an ensemble of twenty first 521 century scenarios. Clim. Dynam., 45(9-10), 2775-2802. 522 3. Airoldi, L. & Beck M. W. (2007). Loss, status and trends for coastal marine 523 habitats of Europe. Oceanogr. Mar. Biol., 45, 345–405 524 4. Andrello, M., Mouillot, D., Somot, S., Thuiller, W., & Manel, S. (2015). 525 Additive effects of climate change on connectivity between marine protected 526 areas and larval supply to fished areas. Divers. Distrib., 21(2), 139-150. 22 527 5. Arias-Ortiz, A., Serrano, O., Masqué, P., Lavery, P. S., Mueller, U., Kendrick, 528 G. et al. (2018). A marine heatwave drives massive losses from the world’s 529 largest seagrass carbon stocks. Nat. Clim. Change, 8(4), 338. 530 6. Bar-On, Y. M., Phillips, R. & Miloa, R. (2018). The biomass distribution on 531 Earth. Proc. Natl. Acad. Sci. U.S.A., 115 (25), 6506–6511. 532 7. Bell, J. J., Davy, S. K., Jones, T., Taylor, M.W. & Webster, N.S. (2013). Could 533 some coral reefs become sponges reefs as our climate changes?. Global change 534 biol., 19(9), 2613-2624. 535 8. Berggren, A. M., Beer, J., Possnert, G., Aldahan, A., Kubik, P., Christl, M. et al. 536 (2009). A 600‐year annual 10Be record from the NGRIP ice core, Greenland. 537 Geophys. Res. Lett., 36(11). 538 9. Bianchi, C. N. (2007). Biodiversity issues for the forthcoming tropical 539 Mediterranean Sea. Hydrobiologia, 580(1), 7. 540 10. Bianchi, C. N., Morri, C., Lasagna, R., Montefalcone, M., Gatti, G., Parravicini, 541 V., & Rovere, A. (2017). Resilience of the marine animal forest: lessons from 542 Maldivian coral reefs after the mass mortality of 1998. In: Marine Animal 543 Forests: the ecology of benthic biodiversity hotspots, Eds. by Rossi S, Bramanti 544 L, Gori A, Orejas C. Springer, Germany. pp. 1241-1269. 545 11. Bopp, L., Resplandy, L., Orr, J. C., Doney, S. C., Dunne, J. P., Gehlen, M. et al. 546 (2013). Multiple stressors of ocean ecosystems in the 21st century: projections 547 with CMIP5 models. Biogeosciences, 10, 6225-6245. 548 12. Borghini, M., Bryden, H., Schroeder, K., Sparnocchia, S. & Vetrano, A. (2014). 549 The Mediterranean is becoming saltier. Ocean Sci., 10(4), 693-700. 23 550 13. Breitburg, D., Levin, L.A., Oschlies, A., Grégoire, M., Chavez, F.P., Conley, 551 D.J. et al. (2018). Declining oxygen in the global ocean and coastal waters. 552 Science, 359(6371), eaam7240. 553 14. Brewer, P. G. & Peltzer, E. T. (2017). Depth perception: the need to report 554 ocean biogeochemical rates as functions of temperature, not depth. Philos. 555 Trans. A, 375(2102), 20160319. 556 15. Brochier, T., Echevin, V., Tam, J., Chaigneau, A., Goubanova, K., & Bertrand, 557 A. (2013). Climate change scenarios experiments predict a future reduction in 558 small pelagic fish recruitment in the Humboldt Current system. Glob. change 559 biol., 19(6), 1841-1853. 560 16. Brümmer, F., Pfannkuchen, M., Baltz, A., Hauser, T. & Thiel, V. (2008). Light 561 inside sponges. J. Exp. Mar. Biol. Ecol., 367(2), 61-64. 562 17. Büscher, J. V., Form, A. U. & Riebesell, U. (2017). Interactive effects of ocean 563 acidification and warming on growth, fitness and survival of the cold-water 564 coral Lophelia pertusa under different food availabilities. Front. Mar. Sci., 4, 565 101. 566 18. Caesar, L., Rahmstorf, S., Robinson, A., Feulner, G. & Saba, V. (2018). 567 Observed fingerprint of a weakening Atlantic Ocean overturning circulation. 568 Nature, 556(7700), 19. 569 19. Cárdenas, C.A. & Montiel, A. (2017). Coexistence in cold waters: animal forests 570 in seaweed-dominated habitats in Southern high-latitudes. In: Marine Animal 571 Forests: The Ecology of Benthic Biodiversity Hotspots, Eds. Rossi S, Bramanti 572 L, Gori A, Orejas C. Springer, Germany. pp. 257-276. 573 20. Caron, D. A. (2016). Mixotrophy stirs up our understanding of marine food 574 webs. Proc. Natl. Acad. Sci. U.S.A., 113 (11), 2806-2808. 24 575 21. Castillo, K. D., Ries, J. B., Bruno, J. F. & Westfield, I. T. (2014). The reef 576 building coral Siderastrea siderea exhibits parabolic responses to ocean 577 acidification and warming. Proc. R. Soc. Lond. B. Biol. Sci., 281(1797), 578 20141856. 579 22. Chust, G., Allen, J. I., Bopp, L., Schrum, C., Holt, J., Tsiaras, K. et al. (2014). 580 Biomass changes and trophic amplification of plankton in a warmer ocean. 581 Global Change Biol., 20(7), 2124-2139. 582 23. Cloern, J. E. (2001). Our evolving conceptual model of the coastal 583 eutrophication problem. Mar. Ecol. Prog. Ser., 210, 223–253. 584 24. Coll, M., Piroddi, C., Albouy, C., Ben Rais Lasram, F., Cheung, W. W., 585 Christensen, V. et al. (2012). The Mediterranean Sea under siege: spatial overlap 586 between marine biodiversity, cumulative threats and marine reserves. Glob. 587 Ecol. Biogeogr., 21(4), 465-480. 588 25. Comeau, S. & Cornwall, C.E. (2017). Contrasting effects of ocean acidification 589 on coral reef “animal forests” versus seaweed “kelp forests”. In: Marine Animal 590 Forests: the ecology of benthic biodiversity hotspots, Eds. Rossi S, Bramanti L, 591 Gori A, Orejas C. Springer, Germany. pp. 1083-1108. 592 26. Cornwall, C. E., Comeau, S. & McCulloch, M. T. (2017). Coralline algae 593 elevate pH at the site of calcification under ocean acidification. Global change 594 biol., 23(10), 4245-4256. 595 27. Cruz, I. C. S., Meira, V. H., de Kikuchi, R. K. P. & Creed, J. C. (2016). The role 596 of competition in the phase shift to dominance of the zoanthid Palythoa cf. 597 variabilis on coral reefs. Mar. environ. res., 115, 28-35. 25 598 28. Curry, R., Dickson, B. & Yashayaev, I. (2003). A change in the freshwater 599 balance of the Atlantic Ocean over the past four decades. Nature, 426, 826–829. 600 doi:10.1038/nature02206. 601 29. D’Alelio, D., Libralato, S., Wyatt, T. & d’Alcalà, M. R. (2016). Ecological- 602 network models link diversity, structure and function in the plankton food-web. 603 Sci. rep., 6, 21806. 604 30. Danovaro, R., Dell’Anno, A., Corinaldesi, C., Magagnini, M., Noble, R., 605 Tamburini, C., &Weinbauer, M. (2008). Major viral impact on the functioning 606 of benthic deep-sea ecosystems. Nature, 454, 1084-1088 607 31. Daufresne, M., Lengfellner, K. & Sommer, U. (2009). Global warming benefits 608 the small in aquatic ecosystems. Proc. Natl. Acad. Sci. U.S.A., 106(31), 12788- 609 12793. 610 32. De Clippele, L. H., Huvenne, V. A. I., Orejas, C., Lundälv, T., Fox, A., Hennige, 611 S. J. & Roberts, J. M. (2018). The effect of local hydrodynamics on the spatial 612 extent and morphology of cold-water coral habitats at Tisler Reef, Norway. 613 Coral Reefs, 37(1), 253-266. 614 33. DeVries, T., Le Quéré, C., Andrews, O., Berthet, S., Hauck, J., Ilyina, T, 615 Landschützer, P., Lenton, A., Lima, I.D., Nowicki, M., Schwinger, J., Séférian, 616 R. (2019). Decadal trends in the ocean carbon sink. Proceedings of the National 617 Academy of Science 116: 11646-11651. 618 34. Di Camillo, C.G., Bavestrello, G., Cerrano, C., Gravili, C., Piraino, S., Puce, S. 619 & Boero, F. (2017). Hydroids (Cnidaria, Hydrozoa): a neglected component of 620 animal forests. In: Marine Animal Forests: the ecology of benthic biodiversity 621 hotspots, Eds. Rossi S, Bramanti L, Gori A, Orejas C. Springer, Germany. pp. 622 397-428. 26 623 35. Doney, S. C. (2006). Oceanography: Plankton in a warmer world. Nature, 624 444(7120), 695. 625 36. Duarte, B., Martins, I., Rosa, R., Matos, A. R., Roleda, M. Y., Reusch, T. et al. 626 (2018). Climate change impacts on seagrass meadows and macroalgal forests: an 627 integrative perspective on acclimation and adaptation potential. Front. Mar. Sci., 628 5, 190 629 37. Edmunds, P. J. (2011). Zooplanktivory ameliorates the effects of ocean 630 acidification on the reef coral Porites spp. Limnol. Oceanogr., 56(6), 2402-2410. 631 38. Edwards, M. & Richardson, A. J. (2004). Impact of climate change on marine 632 pelagic phenology and trophic mismatch. Nature, 430(7002), 881. 633 39. Enríquez, S., Méndez, E. R. & Iglesias‐Prieto, R. (2005). Multiple scattering 634 on coral skeletons enhances light absorption by symbiotic algae. Limnol. 635 Oceanogr., 50(4), 1025-1032. 636 40. Fabricius, K. E., & Klumpp, D. W. (1995). Widespread mixotrophy in reef- 637 inhabiting soft corals: the influence of depth, and colony expansion and 638 contraction on photosynthesis. Marine Ecology Progress Series, 125, 195-204. 639 41. Fanelli, E., Cartes, J. E., Papiol, V., & López-Pérez, C. (2013). Environmental 640 drivers of megafaunal assemblage composition and biomass distribution over 641 mainland and insular slopes of the Balearic Basin (Western Mediterranean). 642 Deep Sea Res Part 1 Oceanogr Res Pap., 78, 79-94. 643 42. Forrest, J. & Miller-Rushing, A. J. (2010). Toward a synthetic understanding of 644 the role of phenology in ecology and evolution. Philos. Trans. R. Soc. Lond. B. 645 Biol. Sci., 3101-3112. 27 646 43. Galli, G., Bramanti, L., Priori, C., Rossi, S., Santangelo, G., Tsounis, G. & 647 Solidoro, C. (2016) Modelling red coral (Corallium rubrum) growth in response 648 to temperature and nutrition. Ecological Modeling 337: 137-148 649 44. Galli, G., Solidoro, C. & Lovato, T. (2017). Marine heat waves hazard 3D maps 650 and the risk for low motility organisms in a warming Mediterranean Sea. Front. 651 Mar. Sci., 4, 136. 652 45. Garrabou, J., Coma, R., Bensoussan, N., Bally, M., Chevaldonné, P., Cigliano, 653 M. et al. (2009). Mass mortality in Northwestern Mediterranean rocky benthic 654 communities: effects of the 2003 heat wave. Global change biol., 15(5), 1090- 655 1103. 656 46. Gili, J. M. & Coma, R. (1998). Benthic suspension feeders: their paramount role 657 in littoral marine food webs. Trends Ecol. Evol., 13(8), 316-321. 658 47. Gooday, A. J., Bett, B. J., Escobar, E., Ingole, B., Levin, L. A., Neira, C. et al. 659 (2010). Habitat heterogeneity and its influence on benthic biodiversity in oxygen 660 minimum zones. Mar. Ecol., 31(1), 125-147. 661 48. Gori, A., Linares, C., Viladrich, N., Clavero, A., Orejas, C., Fiorillo, I. et al. 662 (2013). Effects of food availability on the sexual reproduction and biochemical 663 composition of the Mediterranean gorgonian Paramuricea clavata. J. Exp. Mar. 664 Biol. Ecol., 444, 38-45. 665 49. Greve, M., Gremmen, N. J., Gaston, K. J. & Chown, S. L. (2005). Nestedness of 666 Southern Ocean island biotas: ecological perspectives on a biogeographical 667 conundrum. J. Biogeogr., 32(1), 155-168. 668 50. Griffiths, J. R., Kadin, M., Nascimento, F. J., Tamelander, T., Törnroos, A., 669 Bonaglia, S. et al. (2017). The importance of benthic–pelagic coupling for 28 670 marine ecosystem functioning in a changing world. Global Change Biol., 23(6), 671 2179-2196. 672 51. Guidi, L., Chaffron, S., Bittner, L., Eveillard, D., Larhlimi, A., Roux, S. et al. 673 (2016). Plankton networks driving carbon export in the oligotrophic ocean. 674 Nature, 532(7600), 465. 675 52. Gutt, J., Cummings, V., Dayton, P. Isla, E., Jentsch, A. & Schiapparelle, S. 676 (2017). Antarctic marine animal forests: three-dimensional communities in 677 Souther Ocean ecosystems. Marine Animal Forests: The Ecology of Benthic 678 Biodiversity Hotspots, Eds. Rossi S, Bramanti L, Gori A, Orejas C. Springer, 679 Germany. pp. 315-344. 680 53. Halpern, B. S., Frazier, M., Potapenko, J., Casey, K. S., Koenig, K., Longo, C. et 681 al. (2015). Spatial and temporal changes in cumulative human impacts on the 682 world’s ocean. Nat. Commun., 6, 7615. 683 54. Harasti, D. (2016). Declining seahorse populations linked to loss of essential 684 marine habitats. Mar. Ecol. Prog. Ser., 546, 173-181. 685 55. Harvey, L. D. (2004). Declining temporal effectiveness of carbon sequestration: 686 Implications for compliance with the United National Framework Convention 687 on Climate Change. Clim. Change, 63(3), 259-290. 688 56. Henry, L.A. & Roberts, J.M. (2017). Global biodiversity in cold-water coral 689 reefs ecosystems. In: Marine Animal Forests: the ecology of benthic biodiversity 690 hotspots, Eds. by Rossi S, Bramanti L, Gori A, Orejas C. Springer, Germany. pp. 691 235-256. 692 57. Henson, S., Cole, H., Beaulieu, C. & Yool, A. (2013). The impact of global 693 warming on seasonality of ocean primary production. Biogeosciences, 10(6), 694 4357-4369. 29 695 58. Hoegh – Guldberg, O, Jacob, D, Taylor, M, Bindi, M, Brown, S, Camilloni, I. et 696 al. (2018). Chapter 3: Impacts of 1.5ºC global warming on natural and human 697 systems. In: Global Warming of 1.5 °C an IPCC special report on the impacts of 698 global warming of 1.5 °C above pre-industrial levels and related global 699 greenhouse gas emission pathways, in the context of strengthening the global 700 response to the threat of climate change. Intergovernmental Panel on Climate 701 Change. 702 59. Houlbrèque, F. & Ferrier‐Pagès, C. (2009). Heterotrophy in tropical 703 scleractinian corals. Biol. Rev., 84(1), 1-17. 704 60. Howes, E. L., Joos, F., Eakin, M. & Gattuso, J. P. (2015). An updated synthesis 705 of the observed and projected impacts of climate change on the chemical, 706 physical and biological processes in the oceans. Front. Mar. Sci., 2, 36. 707 61. Hughes, T. P., Barnes, M. L., Bellwood, D. R., Cinner, J. E., Cumming, G. S., 708 Jackson, J. B. et al. (2017). Coral reefs in the Anthropocene. Nature, 546(7656), 709 82. 710 62. Hughes, T.P., Anderson, K.D., Connolly, S.R., Heron, S.F., Kerry, J.T., Lough, 711 J.M. et al. (2018a). Spatial and temporal patterns of mass bleaching of corals in 712 the Anthropocene. Science, 359 (6371), 80-83. 713 63. Hughes, T.P., Kerry, J.T., Baird, A.H., Connolly, S.R., Dietzel, A., Eakin, C.A. 714 et al. (2018b). Global warming transforms coral reef assemblages. Nature, 556, 715 492-496. 716 64. IPCC, (2018). Summary for Policymakers. In: Global warming of 1.5°C. An 717 IPCC Special Report on the impacts of global warming of 1.5°C above pre- 718 industrial levels and related global greenhouse gas emission pathways, in the 719 context of strengthening the global response to the threat of climate change, 30 720 sustainable development, and efforts to eradicate poverty, Eds. V. Masson- 721 Delmotte, P. Zhai, H. O. Pörtner, D. Roberts, J. Skea, P. R. Shukla, A. Pirani, 722 W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J. B. R. Matthews, Y. 723 Chen, X. Zhou, M. I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, T. Waterfield. 724 World Meteorological Organization, Geneva, Switzerland. pp. 32. 725 65. Jackson, J.B.C., (2001). What was natural in the coastal oceans? Proc. Natl. 726 Acad. Sci. U.S.A., 98, 5411-5418. 727 66. Jones, D. O. B., Yool, A., Wei, C-L., Henson, S. A., Ruhl, H. A., Watson, R. A. 728 & Gehlen, M. (2014). Global reductions in seafloor biomass in response to 729 climate change. Global Change Biol., 20, 1861–1872. 730 67. Kahng, S., Copus, J.M. & Wagner, D. (2017). Mesophotic coral ecosystems. In: 731 Marine Animal Forests: the ecology of benthic biodiversity hotspots, Eds. Rossi 732 S, Bramanti L, Gori A, Orejas C. Springer, Germany. pp. 855-886. 733 68. Keil, R. (2017). Anthropogenic forcing of carbonate and organic carbon 734 preservation in marine sediments. Annu. rev. mar. sci., 9, 151-172. 735 69. Keil, R. G., Neibauer, J. A., Biladeau, C., van der Elst, K. & Devol, A. H. 736 (2016). A multiproxy approach to understanding the" enhanced" flux of organic 737 matter through the oxygen-deficient waters of the Arabian Sea. Biogeosciences, 738 13(7), 2077-2092. 739 70. Kuhnz, L. A., Ruhl, H. A., Huffard, C. L. & Smith, Jr, K. L. (2014). Rapid 740 changes and long-term cycles in the benthic megafaunal community observed 741 over 24 years in the abyssal northeast Pacific. Progr. Oceanogr., 124, 1-11. 742 71. Ladd, M.C., Shantz, A.A., Burkepile, D.E. (2019). Newly dominant benthic 743 invertebrates reshape competitive networks on contemporary Caribbean reefs. 744 Coral Reefs https://doi.org/10.1007/s00338-019-01832-6 31 745 72. Laufkötter, C., Vogt, M., Gruber, N., Aita-Noguchi, M., Aumont, O., Bopp, L. 746 et al. (2015). Drivers and uncertainties of future global marine primary 747 production in marine ecosystem models. Biogeosciences, 12, 6955-6984 748 73. Lazzari, P., Mattia, G., Solidoro, C., Salon, S., Crise, A., Zavatarelli, M., Oddo, 749 P. & Vichi, M. (2014) The impacts of climate change and environmental 750 management policies on the trophic regimes in the Mediterranean Sea: Scenario 751 analyses. Journal of Marine Systems, 135, 137-149 752 74. Le Quéré, C., Andres, R. J., Boden, T., Conway, T., Houghton, R. A., House, J. 753 I. et al. (2013). The global carbon budget 1959–2011, Earth Syst. Sci. Data, 5, 754 165–185. 755 75. Learmonth, J. A., MacLeod, C. D., Santos, M. B., Pierce, G. J., Crick, H. Q. P. 756 & Robinson, R. A. (2006). Potential effects of climate change on marine 757 mammals. Ocean. Mar. Biol., 44, 431. 758 76. Lenz, E. A., Bramanti, L., Lasker, H. R. & Edmunds, P. J. (2015). Long-term 759 variation of octocoral populations in St. John, US Virgin Islands. Coral Reefs, 760 34(4),1099–109 761 77. Libralato, S., Caccin, A. & Pranovi, F. (2015). Modeling species invasions using 762 thermal and trophic niche dynamics under climate change. Front. Mar. Sci., 2, 763 29. 764 78. Marbà, N., Jordà, G., Agustí, S., Girard, C., & Duarte, C. M. (2015). Footprints 765 of climate change on Mediterranean Sea biota. Front. Mar. Sci., 2, 56. 766 79. Maxwell, P. S., Eklöf, J. S., van Katwijk, M. M., O'brien, K. R., de la Torre‐ 767 Castro, M., Boström, C. et al. (2017). The fundamental role of ecological 768 feedback mechanisms for the adaptive management of seagrass ecosystems–a 769 review. Biol. Rev., 92(3), 1521-1538 32 770 80. Milisenda, G., Vitale, S., Massi, D., Enea, M., Gancitano, V., Giusto, G. B. et al. 771 (2017). Spatio-temporal composition of discard associated with the deep water 772 rose shrimp fisheries (Parapenaeus longirostris, Lucas 1846) in the south- 773 central Mediterranean Sea. Mediterr. Mar. Sci., 18, 53-63. 774 81. Morgan, K. M., Perry, C. T., Smithers, S. G., Johnson, J. A. & Daniell, J. J. 775 (2016). Evidence of extensive reef development and high coral cover in 776 nearshore environments: implications for understanding coral adaptation in 777 turbid settings. Sci. rep., 6, 29616. Doi: 10.1038/srep29616. 778 82. Munday, P. L., Leis, J. M., Lough, J. M., Paris, C. B., Kingsford, M. J., 779 Berumen, M. L., & Lambrechts, J. (2009). Climate change and coral reef 780 connectivity. Coral reefs, 28(2), 379-395. 781 83. Norström, A. V., Nyström, M., Lokrantz, J. & Folke, C. (2009). Alternative 782 states on coral reefs: beyond coral–macroalgal phase shifts. Mar. Ecol. Prog. 783 Ser., 376, 295-306. 784 84. Orejas, C. & Jiménez, C. (2017). The builders of the oceans-Part I: coral 785 architecture from the tropic to the poles, from shallow to deep. Marine Animal 786 Forests: The Ecology of Benthic Biodiversity Hotspots, pp. 627-656. Ed. by 787 Rossi S, Bramanti L, Gori A, Orejas C. Springer, Germany. 788 85. Parmesan, C. (2007). Influences of species, latitudes and methodologies on 789 estimates of phenological response to global warming. Global Change Biol., 790 13(9), 1860-1872. 791 86. Perry, C. T., Alvarez-Filip, L., Graham, N. A., Mumby, P. J., Wilson, S. K., 792 Kench, P. S. et al. (2018). Loss of coral reef growth capacity to track future 793 increases in sea level. Nature, 558(7710), 396. 33 794 87. Poloczanska, E.S., Burrows, M.T., Brown, C.J., García Molinos, J., Halpern, 795 B.S., Hoegh-Guldberg, O. et al. (2016). Responses of Marine Organisms to 796 Climate Change across Oceans. Front. Mar. Sci., 3,62. doi: 797 10.3389/fmars.2016.00062 798 88. Puig, P., Canals, M., Martín, J., Amblas, D., Lastras, G., Palanques, A. & 799 Calafat, A. M. (2012). Ploughing the deep sea floor. Nature, 489,286-289 800 89. Pusceddu, A., Bianchelli, S., Martín, J., Puig, P., Palanques, A., Masqué, P. & 801 Danovaro, R. (2014). Chronic and intensive bottom trawling impairs deep-sea 802 biodiversity and ecosystem functioning. Proc. Natl. Acad. Sci. U.S.A., 111(24), 803 8861-8866. 804 90. Ramsby, B. D., Shirur, K. P., Iglesias-Prieto, R. & Goulet, T. L. (2014). 805 Symbiodinium photosynthesis in Caribbean octocorals. PLoSONE, 9, e106419 806 91. Reay, D.S., Dentener, F., Grace, J. & Feely, R.A. (2008). Global nitrogen 807 deposition and carbon sinks. Nat. Geosci., 1, 430-431 808 92. Richardson, A. J. & Schoeman, D.S. (2004). Climate Impact on plankton 809 ecosystems in the Northeast Atlantic. Science, 305, 1609-1612 810 93. Rixen, M., Beckers, J. M., Levitus, S., Antonov, J., Boyer, T., Maillard, C. et al. 811 2005). The Western Mediterranean Deep Water: a proxy for climate change. 812 Geophys. Res. Lett., 32(12). 813 94. Rizzo, L., Pusceddu, A., Stabili, L., Alifano, P. & Fraschetti, S. (2017). Potential 814 effects of an invasive seaweed (Caulerpa cylindracea, Sonder) on sedimentary 815 organic matter and microbial metabolic activities. Sci. rep., 7(1), 12113. 816 95. Rocha, L.A., Pinheiro, H.T., Shepherd, B., Papastamatiou, Y.P., Luiz, O.J., Pyle, 817 R.L. & Bongaerts, P. (2018). Mesophotic coral ecosystems are threatened and 34 818 ecologically distinct from shallow water reefs. Science, 361 (6399), 281-284. 819 doi: 10.1126/science.aaq1614 820 96. Rossi, S. (2013). The destruction of the ‘animal forests’ in the oceans: Towards 821 an over-simplification of the benthic ecosystems. Ocean Coast. Manage., 84, 822 77-85 823 97. Rossi, S. & Gili, J.M. (2009). Near bottom phytoplankton and seston: 824 importance in the pelagic-benthic coupling processes. In: Marine Phytoplankton. 825 Eds. William T. Kersey and Samuel P. Munger. Nova Science Publishers Inc, 826 New York. pp 45-85. 827 98. Rossi, S., Gili, J.M., Coma, R., Linares, C., Gori, A. & Vert, N. (2006). 828 Temporal variation in protein, carbohydrate, and lipid concentrations in 829 Paramuricea clavata (Anthozoa, Octocorallia): evidence for summer–autumn 830 feeding constraints. Mar. Biol., 149, 643-651 831 99. Rossi, S., Bramanti, L., Gori, A., & Orejas, C. (2017a). An Overview of the 832 Animal Forests of the World. In: Marine Animal Forests: the ecology of benthic 833 biodiversity hotspots, Eds. Rossi S, Bramanti L, Gori A, Orejas C. Springer, 834 Germany. pp. 1-28. 835 100. Rossi, S., Coppari, M. & Viladrich, N. (2017b). Benthic- 836 Pelagic Coupling: New Perspectives in the Animal Forests. In Marine Animal 837 Forests: the ecology of benthic biodiversity hotspots, Eds. Rossi S, Bramanti L, 838 Gori A, Orejas C. Springer, Germany. pp. 855-886. 839 101. Rossi, S, Schubert, N, Brown, D, Soares, M, Grosso, V, 840 Rangel-Huerta, E. & Maldonado, E. (2018). Linking host morphology and 841 symbiont performance in octocorals. Sci. Rep., 8(1), 12823. 842 DOI:10.1038/s41598-018-31262-3 35 843 102. Rossi, S., Gravili, C., Milisenda, G., Bosch-Belmar, M., De Vito, D. & 844 Piraino, S. (2019) Effects of global warming on reproduction and potential 845 dispersal of Mediterranean cnidarians. The European Zoological Journal DOI 846 10.1080/24750263.2019.1631893Roth, M. S. (2014). The engine of the reef: 847 photobiology of the coral–algal symbiosis. Front. Microbiol., 5, 422. 848 103. Roughgarden, J., Gilbert, S. F., Rosenberg, E., Zilber-Rosenberg, I. & 849 Lloyd, E. A. (2018). Holobionts as units of selection and a model of their 850 population dynamics and evolution. Biol. Theory, 13(1), 44-65. 851 104. Roxy, M. K., Modi, A., Murtugudde, R., Valsala, V., Panickal, S., 852 Prasanna, S. et al. (2016). A reduction in marine primary productivity driven by 853 ràpid warming over the tropical Indian Ocean. Geophys. Res. Lett., 43, 826–833, 854 doi:10.1002/2015GL066979 855 105. Ruzicka, R. R., Colella, M. A., Porter, J. W., Morrison, J. M., Kidney, J. 856 A., Brinkhuis, V. et al. (2013). Temporal changes in benthic assemblages on 857 Florida Keys reefs 11 years after the 1997/1998 El Niño. Mar. Ecol. Prog. Ser., 858 489, 125–41. 859 106. Sanders, D. & Baron-Szabo, R. C. (2005). Scleractinian 860 assemblages under sediment input: their characteristics and relation to the 861 nutrient input concept. Palaeo3, 216(1-2), 139-181. 862 107. Schaper, S. V., Dawson, A., Sharp, P. J., Caro, S. P. & 863 Visser, M. E. (2012). Individual variation in avian reproductive physiology does 864 not reliably predict variation in laying date. Gen. Comp. Endocrinol., 179(1), 53- 865 62. 866 108. Schubert, N., Brown, D. & Rossi, S. (2017). Symbiotic versus asymbiotic 867 octocorals: physiological and ecological implications. In: Marine Animal 36 868 Forests: the ecology of benthic biodiversity hotspots. Eds. Rossi S, Bramanti L, 869 Gori A, Orejas C. Springer, Germany. pp 887-918. 870 109. Semmler, R.F., Hoot, W.C. & Reaka, M.L. (2017). Are mesophotic coral 871 ecosytems distinct communities and can they serve as refugia for shallow reefs? 872 Coral Reefs, 36(2), 433-444. doi: 10.1007/s00338-016-1530-0. 873 110. Shlesinger, T., Grinblat, M., Rapuano, H., Amit, T. & Loya, Y. (2018). 874 Can mesophotic reefs replenish shallow reefs? Reduced coral reproductive 875 performance casts a doubt. Ecology, 99(2), 421-437. 876 111. Sinninger, F., Morita, M & Harii, S. (2013). “Locally extinct” coral 877 species Seriatopora hystrix found at upper mesophotic depths in Okinawa. Coral 878 Reefs, 32, 153 879 112. Smetacek, V. & Cloern, J. E. (2008). On phytoplankton trends. Science, 880 1346-1348. 881 113. Sinniger, F., Ballantine, D., Bejarano, I., Colin, P., Pochon, X., Pomponi, 882 S. & Weil, E. (2016). Biodiversity of mesophotic coral ecosystems. Mesophotic 883 coral ecosystems—a lifeboat for coral reefs, 50-62. 884 114. Soares, M.O., Tavares, T.L. & Carneiro, P.B.M. (2019). Mesophotic 885 ecosystems: Distribution, impacts, and conservation in the South Atlantic. 886 Divers. Distrib., 25(2), 255-268. DOI: 10.1111/ddi.12846 887 115. Steffen, W., Rockström, J., Richardson, K., Lenton, T. M., Folke, C., 888 Liverman, D. et al. (2018). Trajectories of the Earth System in the 889 Anthropocene. Proc. Natl. Acad. Sci. U.S.A., 115(33), 8252-8259. 37 890 116. Steinacher, M., Joos, F., Frölicher, T. L., Bopp, L., Cadule, P., Cocco, V. 891 et al. (2010). Projected 21st century decrease in marine productivity: a multi- 892 model analysis. Biogeosciences, 7, 979–1005. 893 117. Storlazzi, C. D., Elias, E., Field, M. E. & Presto, M. K. (2011). 894 Numerical modeling of the impact of sea-level rise on fringing coral reef 895 hydrodynamics and sediment transport. Coral Reefs, 30, 83–96. 896 118. Sweetman, A. K., Thurber, A. R., Smith, C. R., Levin, L. A., Mora, C., 897 Wei, C. et al. (2017). Major impacts of climate change on deep-sea benthic 898 ecosystems. Elementa-Sci. Anthrop., 5,4. 899 119. Taviani M., Angeletti L., Beuck L., Campiani E., Canese S., Foglini F. et 900 al. (2016). Reprint of 'On and off the beaten track: Megafaunal sessile life and 901 Adriatic cascading processes'. Mar. Geol., 375, 146-160. 902 120. Thrush, S.F. & Dayton, P.K. (2002). Disturbance to marine habitats by 903 trawling and dredging: implications for marine biodiversity. Annu. Rev. Ecol. 904 Evol. Syst., 33, 449-473. 905 121. Thurstan, R. H., Pandolfi, J. M. & zu Ermgassen, P. S. (2017). Animal 906 forests through time: historical data to understand present changes in marine 907 ecosystems. In: Marine Animal Forests: The Ecology of Benthic Biodiversity 908 Hotspots, Eds. Rossi S, Bramanti L, Gori A, Orejas C. Springer, Germany. pp. 909 947-964. 910 122. Towle, E. K., Enochs, I. C. & Langdon, C. (2015). Threatened Caribbean 911 coral is able to mitigate the adverse effects of ocean acidification on calcification 912 by increasing feeding rate. PLoSONE, 10,e0123394 38 913 123. Turner, S. J., Thrush, S. F., Hewitt, J. E., Cummings, V. J. & Funnell, G. 914 (1999). Fishing impacts and the degradation or loss of habitat structure. Fish. 915 Manag. Ecol., 6(5), 401-420. 916 124. Unsworth, R. K., Ambo-Rappe, R., Jones, B. L., La Nafie, Y. A., Irawan, 917 A., Hernawan, U. E. et al. (2018). Indonesia's globally significant seagrass 918 meadows are under widespread threat. Sci. Total Environ., 634, 279-286. 919 125. Vargas-Yáñez, M., García-Martínez, M. C., Moya, F., Balbín, R., López- 920 Jurado, J. L., Serra, M. et al. (2017). Updating temperature and salinity mean 921 values and trends in the Western Mediterranean: The RADMED project. Progr. 922 Oceanogr., 157, 27-46. 923 126. Vargas-Yáñez, M. & Sabatés, A. (2007). Mesoscale high-frequency 924 variability in the Alboran Sea and its influence on fish larvae distributions. J. 925 Mar. Syst., 68(3-4), 421-438. 926 127. Vargas-Yáñez, M., Moya, F., García-Martínez, M. D. C., Tel, E., Zunino, 927 P., Plaza, F. et al. (2010). Climate change in the Western Mediterranean sea 928 1900–2008. J. Mar. Syst., 82(3), 171-176. 929 128. Veron, J. E. N., Hoegh-Guldberg, O., Lenton, T. M., Lough, J. M., 930 Obura, D. O., Pearce-Kelly, P. et al. (2009). The coral reef crisis: The critical 931 importance of < 350 ppm CO2. Mar. Poll. Bull., 58(10), 1428-1436. 932 129. Viola, F., Francipane, A., Caracciolo, D., Pumo, D., La Loggia, G. & 933 Noto, L.V. (2016). Co-evolution of hydrological components under climate 934 change scenarios in the Mediterranean area. Sci. Total Environ., 544, 515-524. 935 130. Watling, L., Guinotte, J., Clark, M. R. & Smith, C. R. (2013). A 936 proposed biogeography of the deep ocean floor. Progr. Oceanogr., 111, 91-112. 39 937 131. Watling, L. & Norse, E. A. (1998). Disturbance of the seabed by mobile 938 fishing gear: a comparison to forest clearcutting. Conserv. Biol., 12(6), 1180- 939 1197. 940 132. Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, 941 B. S., Jackson, J. B. C., Lotze, H. K., Micheli, F., Palumbi, S. R., Sala, E., 942 Selkoe, K. A., Stachowicz, J. J. & Watson, R. (2006). Impacts of biodiversity 943 loss on ocean ecosystem services. Science, 314(5800), 787-790. 944 133. Watson, J. R., Siegel, D. A., Kendall, B. E., Mitarai, S., Rassweiller, A., 945 & Gaines, S. D. (2011). Identifying critical regions in small-world marine 946 metapopulations. Proc. Natl. Acad. Sci. U.S.A., 108(43), E907-E913. 947 134. Yesson, C., Fisher, J., Gorham, T., Turner, C. J., Hammeken Arboe, N., 948 Blicher, M. E. & Kemp, K. M. (2016). The impact of trawling on the epi-benthic 949 megafauna of the west Greenland shelf. – ICES J. Mar. Sci., 74, 866–876. 950 40 951 FIGURES 952 Figure 1. Different marine animal forests of the world, at different depths and latitudes. 953 A) Mussel bed in Patagonia (Chile); B) Caribbean coral reef; C) Hydrocoral Errina ssp. 954 in the Antarctic Peninsula; D) Sponge ground in deep Atlantic waters; E) Mesophotic 955 corals in Hawaii; F) Hydrozoan Solanderia ericopsis with Jason mirabilis nudibranchs; 956 G) Antarctic continental platform sponge ground; H) Mediterranean ascidian 957 Halocyntia papillosa. [Photos from (A) Cárdenas and Montiel, 2017 (© Americo 958 Montiel and César Cárdenas); (B) ADOBE STOCK; (C) Gutt et al., 2017 (© Julian 959 Gutt-Alfred Wegener Institute); (D) Orejas and Jiménez, 2017 (© Pal Buhl-Mortensen, 960 IMR, Norway); (E) Kahng et al., 2017 (© Sam Kahng); (F) Di Camillo et al., 2017 (© 961 Ian Skipworth); (G) Gutt et al., 2017 (© Julian Gutt-Alfred Wegener Institute); (H) 962 Rossi et al. 2017a (© Sergio Rossi)]. 963 Figure 2. Different drivers affecting MAFs of the world. Climate change is already 964 changing the biophysical features of the water column, which have a direct effect on 965 MAFs. Not only sea warming, also ocean acidification, sea level rise and change in 966 circulation patters will surely change the planet seascapes. Repercussions will be 967 different depending on the region and on the dominance of certain benthic organisms, 968 the species interactions, the metabolic constraints, the capability of dispersion and the 969 presence of alien species that may take advantage on the new physical, chemical and 970 biological conditions in the future oceans (artwork by Alberto Gennari). 971 Figure 3. Schematic overview of the abiotic and biotic factors that have a direct (filled 972 and black arrows) or indirect impact (stripped and broken line arrows) on the 973 autotrophic and/or heterotrophic energy input of MAF-forming organisms. 974 41 975 42