KOSMOS mesocosm experiment Gran Canaria 2019 on testing the effect of nutrient composition (Si:N) during artificial upwelling: suspended particulate matter

Suspended particulate matter and elemental stoichiometry data from the mesocosms experiment conducted in the Canary Islands in autumn 2019. Depth-integrated (0-2.5m) water samples were taken in 2-days intervals over the course of 33 days. There was no evidence for significant amounts of particulate inorganic carbon, and therefore, POC and TPC measurements were averaged and interpreted as POC. This “POC TPC average” should be used for further analysis. The upwelling treatment started on day 6. Methodological details in Goldenberg et al. (doi: 10.3389/fmars.2022.1015188)

Seawater carbonate chemistry and risk-taking behavior in prey (shrimps)

Marine prey and predators will respond to future climate through physiological and behavioral adjustments. However, our understanding of how such direct effects may shift the outcome of predator–prey interactions is still limited. Here, we investigate the effects of ocean warming and acidification on foraging behavior and biomass of a common prey (shrimps, Palaemon spp.) tested in large mesocosms harboring natural resources and habitats. Acidification did not alter foraging behavior in prey. Under warming, however, prey showed riskier behavior by foraging more actively and for longer time periods, even in the presence of a live predator. No effects of longer-term exposure to climate stressors were detected on prey biomass. Our findings suggest that ocean warming may increase the availability of some prey to predators via a behavioral pathway (i.e., increased risk-taking by prey), likely by elevating metabolic demand of prey species

Balancing the response to predation-the effects of shoal size, predation risk and habituation on behaviour of juvenile perch

Group size, predation risk and habituation are key drivers of behaviour and evolution in gregarious prey animals. However, the extent to which they interact in shaping behaviour is only partially understood. We analyzed their combined effects on boldness and vigilance behaviour in juvenile perch (Perca fluviatilis) by observing individuals in groups of one, two, three and five faced with four different levels of predation risk in a repeated measures design. The perch showed an asymptotic increase in boldness with increasing group size and the highest per capita vigilance in groups of two. With increasing predation risk, individuals reduced boldness and intensified vigilance. The interaction between group size and predation risk influenced vigilance but not boldness. In this context, individuals in groups of two elevated their vigilance compared to individuals in larger groups only when at higher risk of predation. Further, as only group size, they significantly reduced vigilance at the highest level of risk. With increasing habituation, solitary individuals became considerably bolder. Also, predation risk affected boldness only in the more habituated situation. Hence, repeated measures may be essential to correctly interpret certain relationships in behaviour. Our results suggest that perch may adjust boldness behaviour to group size and predation risk independently. This is rather unexpected since in theory, natural selection would strongly favour an interactive adjustment. Finally, vigilance might be particularly effective in groups of two due to the intense monitoring and detailed response to changing levels of risk

Ocean warming increases availability of crustacean prey via riskier behavior

Marine prey and predators will respond to future climate through physiological and behavioral adjustments. However, our understanding of how such direct effects may shift the outcome of predator–prey interactions is still limited. Here, we investigate the effects of ocean warming and acidification on foraging behavior and biomass of a common prey (shrimps, Palaemon spp.) tested in large mesocosms harboring natural resources and habitats. Acidification did not alter foraging behavior in prey. Under warming, however, prey showed riskier behavior by foraging more actively and for longer time periods, even in the presence of a live predator. No effects of longer-term exposure to climate stressors were detected on prey biomass. Our findings suggest that ocean warming may increase the availability of some prey to predators via a behavioral pathway (i.e., increased risk-taking by prey), likely by elevating metabolic demand of prey species

Combining mesocosms with models reveals effects of global warming and ocean acidification on a temperate marine ecosystem

Ocean warming and species exploitation have already caused large‐scale reorganization of biological communities across the world. Accurate projections of future biodiversity change require a comprehensive understanding of how entire communities respond to global change. We combined a time‐dynamic integrated food web modeling approach (Ecosim) with previous data from community‐level mesocosm experiments to determine the independent and combined effects of ocean warming, ocean acidification and fisheries exploitation on a well‐managed temperate coastal ecosystem. The mesocosm parameters enabled important physiological and behavioral responses to climate stressors to be projected for trophic levels ranging from primary producers to top predators, including sharks. Through model simulations, we show that under sustainable rates of fisheries exploitation, near‐future warming or ocean acidification in isolation could benefit species biomass at higher trophic levels (e.g., mammals, birds, and demersal finfish) in their current climate ranges, with the exception of small pelagic fishes. However, under warming and acidification combined, biomass increases at higher trophic levels will be lower or absent, while in the longer term reduced productivity of prey species is unlikely to support the increased biomass at the top of the food web. We also show that increases in exploitation will suppress any positive effects of human‐driven climate change, causing individual species biomass to decrease at higher trophic levels. Nevertheless, total future potential biomass of some fisheries species in temperate areas might remain high, particularly under acidification, because unharvested opportunistic species will likely benefit from decreased competition and show an increase in biomass. Ecological indicators of species composition such as the Shannon diversity index decline under all climate change scenarios, suggesting a trade‐off between biomass gain and functional diversity. By coupling parameters from multilevel mesocosm food web experiments with dynamic food web models, we were able to simulate the generative mechanisms that drive complex responses of temperate marine ecosystems to global change. This approach, which blends theory with experimental data, provides new prospects for forecasting climate‐driven biodiversity change and its effects on ecosystem processes

KOSMOS mesocosm experiment Gran Canaria 2019 on testing the effect of nutrient composition (Si:N) during artificial upwelling: environment, nutrients and carbonate chemistry

Physio-chemical data from the mesocosms experiment conducted in the Canary Islands in autumn 2019. Values are depth-integrated averages in (mostly) 2-days intervals over the course of 33 days. The upwelling treatment started on day 6. Oxygen (O2), salinity, temperature, photosynthetically active radiation (PAR) and pH were measured from 0.3 to 2.5 m depth via three replicate CTD casts. Dissolved inorganic carbon (DIC) and the inorganic nutrients nitrite (NO2), combined nitrate and nitrite (NO3 + NO2), ammonia (NH4), phosphate (PO4) and silicate (Si(OH)4) were measured in triplicates on depth integrated water samples from 0 to 2.5 m depth. Total alkalinity (TA) was measured from the same water samples but in duplicates. Then, pCO2 and nitrate was calculated. Methodological details in Goldenberg et al. (doi:10.3389/fmars.2022.1015188)

Trophic pyramids reorganize when food web architecture fails to adjust to ocean change

As human activities intensify, the structures of ecosystems and their food webs often reorganize. Through the study of mesocosms harboring a diverse benthic coastal community, we reveal that food web architecture can be inflexible under ocean warming and acidification and unable to compensate for the decline or proliferation of taxa. Key stabilizing processes, including functional redundancy, trophic compensation, and species substitution, were largely absent under future climate conditions. A trophic pyramid emerged in which biomass expanded at the base and top but contracted in the center. This structure may characterize a transitionary state before collapse into shortened, bottom-heavy food webs that characterize ecosystems subject to persistent abiotic stress. We show that where food web architecture lacks adjustability, the adaptive capacity of ecosystems to global change is weak and ecosystem degradation likely

Seawater carbonate chemistry and food web composition, productivity, and trophic architecture

As human activities intensify, the structures of ecosystems and their food webs often reorganize. Through the study of mesocosms harboring a diverse benthic coastal community, we reveal that food web architecture can be inflexible under ocean warming and acidification and unable to compensate for the decline or proliferation of taxa. Key stabilizing processes, including functional redundancy, trophic compensation, and species substitution, were largely absent under future climate conditions. A trophic pyramid emerged in which biomass expanded at the base and top but contracted in the center. This structure may characterize a transitionary state before collapse into shortened, bottom-heavy food webs that characterize ecosystems subject to persistent abiotic stress. We show that where food web architecture lacks adjustability, the adaptive capacity of ecosystems to global change is weak and ecosystem degradation likely

Seawater carbonate chemistry and trophic flows and the living biomass of detritivores, herbivores, and carnivores

Global warming and ocean acidification are forecast to exert significant impacts on marine ecosystems worldwide. However, most of these projections are based on ecological proxies or experiments on single species or simplified food webs. How energy fluxes are likely to change in marine food webs in response to future climates remains unclear, hampering forecasts of ecosystem functioning. Using a sophisticated mesocosm experiment, we model energy flows through a species-rich multilevel food web, with live habitats, natural abiotic variability, and the potential for intra- and intergenerational adaptation. We show experimentally that the combined stress of acidification and warming reduced energy flows from the first trophic level (primary producers and detritus) to the second (herbivores), and from the second to the third trophic level (carnivores). Warming in isolation also reduced the energy flow from herbivores to carnivores, the efficiency of energy transfer from primary producers and detritus to herbivores and detritivores, and the living biomass of detritivores, herbivores, and carnivores. Whilst warming and acidification jointly boosted primary producer biomass through an expansion of cyanobacteria, this biomass was converted to detritus rather than to biomass at higher trophic levels-i.e., production was constrained to the base of the food web. In contrast, ocean acidification affected the food web positively by enhancing trophic flow from detritus and primary producers to herbivores, and by increasing the biomass of carnivores. Our results show how future climate change can potentially weaken marine food webs through reduced energy flow to higher trophic levels and a shift towards a more detritus-based system, leading to food web simplification and altered producer–consumer dynamics, both of which have important implications for the structuring of benthic communities

Living biomass of primary producers (trophic level 1), primary consumers (level 2), and secondary consumers (level 3) across functional groups within the mesocosms.

<p>The biomass of functional groups with intermediate trophic levels (e.g., trophic level of filter feeders = 2.4) was assigned to the levels 2 and 3 according to their relative contribution to trophic flow (e.g., 60% to level 2 and 40% to level 3). At the third trophic level, the decrease in biomass under T and OAT is primarily driven by filter feeders, while a negative effect was not apparent in most other functional groups such as the fishes (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2003446#pbio.2003446.s002" target="_blank">S2 Fig</a>). Living biomass includes 16 functional groups excluding detritus. Values are means ± SE across mesocosms (<i>n</i> = 3). Significant interactions or main effects (<i>p</i> < 0.05) within trophic levels are based on two-way ANOVAs (df = 1,8) and are indicated with asterisks. See <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2003446#pbio.2003446.s011" target="_blank">S2 Table</a> for statistical test outcomes. Means with different lowercase letters indicate significant difference among treatments based on posthoc tests corrected for false discovery rate and done separately for different trophic levels. C, control; OA, elevated CO₂, OAT, elevated CO₂ and temperature; T, elevated temperature.</p