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1. Widespread habitat loss leads to ecosystem‐scale decrease in trophic function

   https://doi.org/10.1111/gcb.17263  

   James, W. Ryan ; Furman, Bradley T. ; Rodemann, Jonathan R. ; Costa, Sophia V. ; Fratto, Zachary W. ; Nelson, James A. ; Rehage, Jennifer S. ; Santos, Rolando O. ( March 2024 , Global Change Biology)

   Natural and anthropogenic disturbances have led to rapid declines in the amount and quality of available habitat in many ecosystems. Many studies have focused on how habitat loss has affected the composition and configuration of habitats, but there have been fewer studies that investigate how this loss affects ecosystem function. We investigated how a large‐scale seagrass die‐off altered the distribution of energetic resources of three seagrass‐associated consumers with varied resource use patterns. Using long‐term benthic habitat monitoring data and resource use data from Bayesian stable isotope mixing models, we generated energetic resource landscapes (E‐scapes) annually between 2007 and 2019.E‐scapes link the resources being used by a consumer to the habitats that produce those resources to calculate a habitat resource index as a measurement of energetic quality of the landscape. Overall, our results revealed that following the die‐off there was a reduction in trophic function across all species in areas affected by the die‐off event, but the response was species‐specific and dependent on resource use and recovery patterns. This study highlights how habitat loss can lead to changes in ecosystem function. Incorporating changes in ecosystem function into models of habitat loss could improve understanding of how species will respond to future change.

    

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2. Aquatic and terrestrial resources are not nutritionally reciprocal for consumers

   https://doi.org/10.1111/1365-2435.13401  

   Twining, Cornelia W. ; Brenna, J. Thomas ; Lawrence, Peter ; Winkler, David W. ; Flecker, Alexander S. ; Hairston, Jr., Nelson G. ; Allen, ed., Daniel C. ( July 2019 , Functional Ecology)

   Aquatic and terrestrial ecosystems are connected through reciprocal fluxes of energy and nutrients that can subsidize consumers. Past research on reciprocal aquatic–terrestrial subsidies to consumers has generally focused on subsidy quantity while ignoring major differences in the nutritional composition of aquatic and terrestrial resources. Because aquatic resources contain substantially more highly unsaturated omega‐3 fatty acids (HUFAs) than terrestrial resources, aquatic subsidies may play a unique role by supplying these critical compounds to both aquatic and terrestrial consumers.

   Here, we first characterized nutritional quality in terms of HUFA content in aquatic and terrestrial insect prey. We then used bulk stable isotope analyses to estimate subsidy use by stream and riparian consumers coupled with compound‐specific stable isotope analyses, which allowed us to document consumer HUFA sources. Finally, in order to understand the nutritional importance of aquatic‐derived HUFAs for riparian consumers, we conducted manipulative diet experiments on Eastern Phoebe (Sayornis phoebe) chicks in the laboratory.

   Aquatic insects were significantly enriched in HUFAs, mainly in terms of eicosapentaenoic acid (EPA), compared with terrestrial insects. Stream fishes relied mainly upon aquatic resources, while insectivorous birds varied in their use of aquatic subsidies across sites. However, like stream fishes, Eastern Phoebe chicks received HUFAs from aquatic insects, even when they were heavily reliant upon terrestrial insects for their overall diet. In the laboratory, dietary HUFAs, such as those supplied by aquatic insects, increased the growth rate and condition of Eastern Phoebe chicks.

   This study demonstrates that aquatic and terrestrial subsidies are not nutritionally reciprocal from the perspective of consumers because aquatic resources are the main source of critical fatty acids for both stream and riparian consumers. It also confirms previous findings on the nutritional importance of HUFAs for riparian birds, demonstrating that an insectivorous riparian lifestyle influences avian nutritional needs. Finally, our findings raise the possibility that birds and other riparian insectivores may experience nutritional mismatches with terrestrial prey if they do not have access to high‐quality aquatic subsidies as a consequence of aquatic habitat degradation or shifts in consumer and resource phenology.

   A freePlain Language Summarycan be found within the Supporting Information of this article.

    

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3. Temporal scale of habitat selection for large carnivores: Balancing energetics, risk and finding prey

   https://doi.org/10.1111/1365-2656.13613  

   Nisi, Anna C. ; Suraci, Justin P. ; Ranc, Nathan ; Frank, Laurence G. ; Oriol‐Cotterill, Alayne ; Ekwanga, Steven ; Williams, Terrie M. ; Wilmers, Christopher C. ( October 2021 , Journal of Animal Ecology)

   When navigating heterogeneous landscapes, large carnivores must balance trade‐offs between multiple goals, including minimizing energetic expenditure, maintaining access to hunting opportunities and avoiding potential risk from humans. The relative importance of these goals in driving carnivore movement likely changes across temporal scales, but our understanding of these dynamics remains limited.

   Here we quantified how drivers of movement and habitat selection changed with temporal grain for two large carnivore species living in human‐dominated landscapes, providing insights into commonalities in carnivore movement strategies across regions.

   We used high‐resolution GPS collar data and integrated step selection analyses to model movement and habitat selection for African lionsPanthera leoin Laikipia, Kenya and pumasPuma concolorin the Santa Cruz Mountains of California across eight temporal grains, ranging from 5 min to 12 hr. Analyses considered landscape covariates that are related to energetics, resource acquisition and anthropogenic risk.

   For both species, topographic slope, which strongly influences energetic expenditure, drove habitat selection and movement patterns over fine temporal grains but was less important at longer temporal grains. In contrast, avoiding anthropogenic risk during the day, when risk was highest, was consistently important across grains, but the degree to which carnivores relaxed this avoidance at night was strongest for longer term movements. Lions and pumas modified their movement behaviour differently in response to anthropogenic features: lions sped up while near humans at fine temporal grains, while pumas slowed down in more developed areas at coarse temporal grains. Finally, pumas experienced a trade‐off between energetically efficient movement and avoiding anthropogenic risk.

   Temporal grain is an important methodological consideration in habitat selection analyses, as drivers of both movement and habitat selection changed across temporal grain. Additionally, grain‐dependent patterns can reflect meaningful behavioural processes, including how fitness‐relevant goals influence behaviour over different periods of time. In applying multi‐scale analysis to fine‐resolution data, we showed that two large carnivore species in very different human‐dominated landscapes balanced competing energetic and safety demands in largely similar ways. These commonalities suggest general strategies of landscape use across large carnivore species.

    

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4. Opportunities for the conservation of migratory birds to benefit threatened resident vertebrates in the Neotropics

   https://doi.org/10.1111/1365-2664.14077  

   Wilson, Scott ; Lin, Hsien‐Yung ; Schuster, Richard ; González, Ana M. ; Gómez, Camila ; Botero‐Delgadillo, Esteban ; Bayly, Nicholas J. ; Bennett, Joseph R. ; Rodewald, Amanda D. ; Roehrdanz, Patrick R. ; et al ( November 2021 , Journal of Applied Ecology)

   Neotropical countries receive financing and effort from temperate nations to aid the conservation of migratory species that move between temperate and tropical regions. If allocated strategically, these resources could simultaneously contribute to other conservation initiatives. In this study, we use novel distribution maps to show how those resources could aid planning for the recovery of threatened resident vertebrates.

   Using eBird‐based relative abundance estimates, we first identified areas with high richness of Neotropical migrant landbirds of conservation concern (23 species) during the stationary non‐breeding period. Within these areas, we then identified threatened species richness, projected forest loss and conducted a prioritization for 1,261 red‐listed vertebrates using Terrestrial Area‐of‐Habitat maps.

   Richness for migrants was greatest along a corridor from the Yucatan peninsula south to the northern Andes but also included south‐west Mexico and Hispaniola. Protected areas account for 22% of this region while 21% is at risk of forest loss. Within this focal region for migrants, all four vertebrate groups showed hotspots of threatened species richness along the west and east Andean slopes. Taxa‐specific hotspots included montane areas of southern Mexico and central Guatemala (amphibians/reptiles) and the entire east slope of the Colombian East Andes (mammals).

   Our prioritization highlighted several areas of importance for conservation due to high threatened species richness and projected forest loss including (a) the Pacific dry forests of south‐west Mexico, (b) montane regions of northern Central America and (c) the west Andean slope of Colombia and Ecuador. At a landscape scale in southern Colombia, we show how conservation efforts for six Neotropical migrants could benefit 56 threatened residents that share a similar elevational range.

   Synthesis and applications. Funding and effort for migratory bird conservation also has potential to benefit threatened resident vertebrates in the Neotropics. Our study highlights how novel, high‐resolution information on species distributions and risk of forest loss can be integrated to identify priority areas for the two groups at regional and landscape scales. The approach and data can be further modified for more specific goals, such as within‐country initiatives.

    

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5. Effects of increased temperature on arctic slimy sculpin Cottus cognatus is mediated by food availability: Implications for climate change

   https://doi.org/10.1111/fwb.13659  

   Pennock, Casey A. ; Budy, Phaedra ; Atkinson, Carla L. ; Barrett, Nick ( December 2020 , Freshwater Biology)

   Lakes are vulnerable to climate change, and warming rates in the Arctic are faster than anywhere on Earth. Fishes are sensitive to changing temperatures, which directly control physiological processes. Food availability should partly dictate responses to climate change because energetic demands change with temperature, but few studies have simultaneously examined temperature and food availability.

   We used a fully factorial experiment to test effects of food availability and temperature (7.6, 12.7, and 17.4°C; 50 days) on growth, consumption, respiration, and excretion, and effects of temperature (12 and 19.3°C; 27 days) on habitat use and growth of a common, but understudied, mid‐level consumer, slimy sculpinCottus cognatus, in arctic lakes. We also used bioenergetics modelling to predict consumptive demand under future warming scenarios.

   Growth rates were 3.4× higher at 12.7°C in high food compared to low food treatments, but the magnitude of differences depended on temperature. Within low food treatments, there was no statistical difference in growth rates among temperatures, suggesting food limitation. Consumption, respiration, and nitrogen excretion increased with temperature independent of food availability. Lower growth rates coincided with lower phosphorus excretion at the highest temperature, suggesting that fish selectively retained phosphorus at high temperatures and low food. In habitat choice experiments, fish were more likely to use the 12°C side of the tank, closely matching their optimal temperature. We predicted a 9% increase in consumption is required to maintain observed growth under a 4°C warming scenario.

   These results highlight considering changes in food resources and other associated indirect effects (e.g. excretion) that accompany changing temperatures with climate change. Depending on how food webs respond to warming, fish may cope with predicted warming if density‐dependent feedback maintains population sizes.

    

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