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1. The metabolic underpinnings of temperature-dependent predation in a key marine predator

   https://doi.org/10.3389/fmars.2023.1072807  

   Csik, Samantha R.; DiFiore, Bartholomew P.; Kraskura, Krista; Hardison, Emily A.; Curtis, Joseph S.; Eliason, Erika J.; Stier, Adrian C. (February 2023, Frontiers in Marine Science)

   IntroductionChanges in temperature can fundamentally transform how species interact, causing wholesale shifts in ecosystem dynamics and stability. Yet we still have a limited understanding of how temperature-dependence in physiology drives temperature-dependence in species-interactions. For predator-prey interactions, theory predicts that increases in temperature drive increases in metabolism and that animals respond to this increased energy expenditure by ramping up their food consumption to meet their metabolic demand. However, if consumption does not increase as rapidly with temperature as metabolism, increases in temperature can ultimately cause a reduction in consumer fitness and biomass via starvation. MethodsHere we test the hypothesis that increases in temperature cause more rapid increases in metabolism than increases in consumption using the California spiny lobster (Panulirus interruptus) as a model system. We acclimated individual lobsters to temperatures they experience sacross their biogeographic range (11, 16, 21, or 26°C), then measured whether lobster consumption rates are able to meet the increased metabolic demands of rising temperatures. Results and discussionWe show positive effects of temperature on metabolism and predation, but in contrast to our hypothesis, rising temperature caused lobster consumption rates to increase at a faster rate than increases in metabolic demand, suggesting that for the mid-range of temperatures, lobsters are capable of ramping up consumption rates to increase their caloric demand. However, at the extreme ends of the simulated temperatures, lobster biology broke down. At the coldest temperature, lobsters had almost no metabolic activity and at the highest temperature, 33% of lobsters died. Our results suggest that temperature plays a key role in driving the geographic range of spiny lobsters and that spatial and temporal shifts in temperature can play a critical role in driving the strength of species interactions for a key predator in temperate reef ecosystems. 

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2. Sounds of a changing sea: Temperature drives acoustic output by dominant biological sound-producers in shallow water habitats

   https://doi.org/10.3389/fmars.2022.960881  

   Lillis, Ashlee; Mooney, T. Aran (August 2022, Frontiers in Marine Science)

   The ocean’s soundscape is fundamental to marine ecosystems, not only as a source of sensory information critical to many ecological processes but also as an indicator of biodiversity and habitat health. Yet, little is known about how ecoacoustic activity in marine habitats is altered by environmental changes such as temperature. The sounds produced by dense colonies of snapping shrimp dominate temperate and tropical coastal soundscapes worldwide and are a major driver broadband sound pressure level (SPL) patterns. Field recordings of soundscape patterns from the range limit of a snapping shrimp distribution showed that rates of snap production and associated SPL were closely positively correlated to water temperature. Snap rates changed by 15-60% per °C change in regional temperature, accompanied by fluctuations in SPL between 1-2 dB per °C. To test if this relationship was due to a direct effect of temperature, we measured snap rates in controlled experiments using two snapping shrimp species dominant in the Western Atlantic Ocean and Gulf of Mexico ( Alpheus heterochaelis and A. angulosus ). Snap rates were measured for shrimp held at different temperatures (across 10-30 °C range, with upper limit 2°C above current summer mean temperatures) and under different social groupings. Temperature had a significant effect on shrimp snap rates for all social contexts tested (individuals, pairs, and groups). For individuals and shrimp groups, snap production more than doubled between mid-range (20°C) and high (30°C) temperature treatments. Given that snapping shrimp sounds dominate the soundscapes of diverse habitats, including coral reefs, rocky bottoms, seagrass, and oyster beds, the strong influence of temperature on their activity will potentially alter soundscape patterns broadly. Increases in ambient sound levels driven by elevated water temperatures has ecological implications for signal detection, communication, and navigation in key coastal ecosystems for a wide range of organisms, including humans. 

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3. Effects of season and latitude on the diet quality of the invasive Asian shore crab Hemigrapsus sanguineus

   https://doi.org/10.3354/meps14231  

   Reese, TC; Alder, J; Asay, EG; Blakeslee, AMH; Cabrera, D; Crane, LC; Fletcher, LS; Pinkston, E; Repetto, MF; Smith, N; et al (January 2023, Marine Ecology Progress Series)

   Invasive species alter invaded ecosystems via direct impacts such as consumption. In turn, an invasive species’ ability to thrive in new habitats depends on its ability to exploit available resources, which may change over time and space. Diet quality and quantity are indicators of a consumer’s consumptive effects and can be strongly influenced by season and latitude. We examined the effects of season and latitude on the diet quality and quantity of the invasive Asian shore crab Hemigrapsus sanguineus throughout a non-winter sampling year at 5 different sites spanning 8° of latitude across its invaded United States range. We found that diet quality, averaged through time, largely follows an expected latitudinal cline, being higher in the center of its range and lower toward the southern and northern edges. We also found that while some sites show similar patterns of diet quality variation with season, no pattern is consistent across all latitudes. Finally, we found that crabs at sites with low diet quality during summer reproductive months did not compensate by increasing total consumption. Because the Asian shore crab is an important consumer in its invaded ecosystems, understanding how its diet quality and quantity vary with season and latitude can help us better understand how this species influences trophic interactions and community structure, how it has been able to establish across a wide ecological and environmental range, and where future range expansion is most likely to occur. 

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4. Rising temperature non‐additively alters how different dimensions of biodiversity affect ecosystem‐scale processes

   https://doi.org/10.1111/1365-2656.70255  

   Richards, Sean Pierce; Hesselbarth, Maximilian_H K; Allgeier, Jacob Edward (April 2026, Journal of Animal Ecology)

   Abstract Improving our ability to predict when and how biodiversity mediates ecosystem processes requires greater consideration of how different dimensions of biodiversity, such as species‐specific physiology or behaviour, can independently and interactively affect these processes. Global change drivers, such as increased temperature, can also alter organismal metabolism in ways that may interact with different dimensions of biodiversity, further reducing predictability.Using an individual‐based model of a seagrass‐patch reef ecosystem, we quantified (1) how species‐level physiological traits of two common reef fish, (2) foraging behaviours and (3) increasing water temperatures interacted to affect ecosystem‐level primary production (PP) via consumer nutrient excretion.At ambient temperature, physiology more strongly regulated ecosystem PP than behaviour, which primarily influenced where PP occurred. Increased temperature strongly independently resulted in greater ecosystem PP until a threshold whereafter ecosystem PP drastically decreased for both fish species. Temperature strongly interacted with physiology to non‐additively increase ecosystem PP but only weakly interacted with behaviour due to underlying metabolic mechanisms.Our study highlights the importance of species‐level physiology for regulating ecological processes and that increased temperatures will alter biodiversity‐ecosystem process relationships in unpredictable ways.Importantly, because we quantified both the direct effects of physiology and behaviour on nutrient supply via excretion and the indirect effects of this on primary production, we were able to determine that quantifying consumer‐mediated nutrient supply alone was insufficient to predict ecosystem‐scale primary production.Our findings emphasize that understanding the mechanisms by which biodiversity affects ecosystems requires quantifying ecosystem‐scale responses, which also places findings at scales relevant for conservation. 

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5. Intrinsic and extrinsic drivers of organic matter processing along phosphorus and salinity gradients in coastal wetlands

   https://doi.org/10.1111/1365-2745.14302  

   Anderson, Kenneth J; Kominoski, John S; Sah, Jay P (March 2024, Journal of Ecology)

   Abstract Climate change is accelerating sea‐level rise and saltwater intrusion in coastal regions world‐wide and interacting with large‐scale changes in species composition in coastal wetlands. Quantifying macrophyte litter breakdown along freshwater‐to‐marine coastal gradients is needed to predict how carbon stores will respond to shifts in both macrophyte communities and water chemistry under changing environmental conditions.To test the interactive drivers of changing species identity and water chemistry, we performed a reciprocal transplant of four macrophyte litter species in seven sites along freshwater‐to‐marine gradients in the Florida Coastal Everglades. We measured surface water chemistry (dissolved organic carbon, total nitrogen and total phosphorus), litter chemistry (% nitrogen, % phosphorus, change in N:P molar ratio, % cellulose and % lignin as proxies for recalcitrance) and litter breakdown rates (k/degree‐day).Direct effects of salinity and surface water nutrients were the strongest drivers ofk, but unexpectedly, litter chemistry did not correlate with litterk. However, salinity strongly correlated with changes in litter chemistry, whereby litter incubated in brackish and marine wetlands was more labile and gained more phosphorus compared with litter in freshwater marshes. Our results suggest that litterkin coastal wetlands is explained by species‐specific interactions among water and litter chemistries. Water nutrient availability was an important predictor of breakdown rates across species, but breakdown rates were only explained by the carbon recalcitrance of litter in the species with the slowest breakdown (Cladium jamaicense), indicating the importance of carbon structure, and species identity on breakdown rates.Synthesis. In oligotrophic ecosystems, nutrients are often the primary driver of organic matter breakdown. However, we found that variation in macrophyte breakdown rates in oligotrophic coastal wetlands was also explained by salinity and associated seawater chemistry, emphasising the need to understand how saltwater intrusion will alter organic matter processing in wetlands. Our results suggest that marine subsidies associated with sea‐level rise have the potential to accelerate leaf litter breakdown. The increase in breakdown rates could either be buffered or increase further as sea‐level rise also shifts macrophyte community composition to more or less recalcitrant species. 

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