Climate drives the geography of marine consumption by changing predator communities

Abstract

The global distribution of primary production and consumption by humans (fisheries) is well-documented, but we have no map linking the central ecological process of consumption within food webs to temperature and other ecological drivers. Using standardized assays that span 105° of latitude on four continents, we show that rates of bait consumption by generalist predators in shallow marine ecosystems are tightly linked to both temperature and the composition of consumer assemblages. Unexpectedly, rates of consumption peaked at midlatitudes (25 to 35°) in both Northern and Southern Hemispheres across both seagrass and unvegetated sediment habitats. This pattern contrasts with terrestrial systems, where biotic interactions reportedly weaken away from the equator, but it parallels an emerging pattern of a subtropical peak in marine biodiversity. The higher consumption at midlatitudes was closely related to the type of consumers present, which explained rates of consumption better than consumer density, biomass, species diversity, or habitat. Indeed, the apparent effect of temperature on consumption was mostly driven by temperature-associated turnover in consumer community composition. Our findings reinforce the key influence of climate warming on altered species composition and highlight its implications for the functioning of Earth’s ecosystems.

Stronger predation intensity and impact on prey communities in the tropics

“…Our study provides a novel integration of large-scale experimental and observational approaches to explore interactions among communities of predators and prey. Our results expand the growing literature that shows stronger predation at lower latitudes in both marine and terrestrial systems (Schemske et al 2009, Roslin et al 2017, Reynolds et al 2018, Hargreaves et al 2019, Longo et al 2019, Freestone et al 2020, but contrast with studies that find consumption rates of standardized bait can peak at midlatitudes for some groups of marine predators (Musrri et al 2019, Roesti et al 2020, Whalen et al 2020. Subsets of predators may demonstrate different consumption patterns across latitude because of differences in abundance and composition of specific predator taxa or geographic variation in abiotic patterns along different coastlines.…”

“…To quantify predation intensity, studies that span biogeographic scales often assess predation rates (Jeanne 1979, Bertness et al 1981, Heck and Wilson 1987, Roslin et al 2017, Hargreaves et al 2019, Longo et al 2019, Roesti et al 2020, Whalen et al 2020, which have clear value in estimating top-down forcing in a community. Multiple dimensions of the predator community, however, contribute to predation intensity beyond predation rates and can vary among regions.…”

The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans

“…We predicted: (i) that trait dispersion would increase with decreasing latitude as species interactions become more intense, and (ii) that abiotic filters would be strongest and result in clustering at higher latitudes and where biotic interactions are weak. While marine systems often show nonlinear variation in species diversity and interaction strength with latitude (peaking at mid-latitudes; [ 20 , 31 ]), our predictions are reasonable within the range of latitudes occupied by eelgrass (approx. 30–70° N).…”

“…On the other hand, selection for tolerance of extreme heat conditions could also cause trait clustering at low latitudes. Finally, patterns in community structure along latitudinal gradients could be dominated by idiosyncratic and historically contingent effects of predators, prey, competitors, and mutualists that vary among biogeographic provinces [ 17 – 20 ]. Local abiotic factors, habitat complexity, assemblage composition and adaptation to these local factors could further obscure broader geographical patterns of community assembly [ 17 , 21 ], stressing the importance of assessing patterns across multiple independent species pools.…”

Data_Sheet_1.csv

“…Understanding spatial and temporal variation in consumption is crucial for predicting how ecosystems will respond to global and local change, including warming climate and fishing impacts (Ling et al, 2009;Vergés et al, 2011). Although relative variation in primary production and producer biomass can be compared efficiently in both terrestrial and marine environments, the mobility, diet, and behavior of consumers (e.g., fishes) make their distribution and top-down impacts challenging to quantify, especially in marine habitats (Duffy et al, 2015;Fraser et al, 2020;Whalen et al, 2020). However, an increasing number of studies have demonstrated that top-down processes vary predictably across latitude within a handful of marine habitats (Freestone et al, 2011;Rodemann and Brandl, 2017;Musrri et al, 2019;Whalen et al, 2020;Lefcheck et al, 2021), which may give insight into fish presence and behaviors, and help with the interpretation of consumption processes (Ferreira et al, 2004;Navarrete et al, 2005).…”