Predator Size Research Articles

Littoral resources, food chain length and top predator size - Are these connected with lake size?

Littoral resources, food chain length and top predator size - Are these connected with lake size?

Gape-limited invasive predator frequently kills avian prey that are too large to swallow.

Gape-limited predators (e.g., snakes, many fish) are not generally expected to pose a predation threat to prey that are too large for them to swallow. However, the extent to which snakes predate on prey that exceed their gape limitation remains largely unknown. We conducted the first study to investigate the influence of both prey and predator sizes on the frequency of ingestion success by snakes in a natural system. We combined survival monitoring of an avian prey species (Aplonis opaca) via radio-telemetry with a survey of the size distribution of their major predator (Boiga irregularis) on Guam. This allowed us to assess (1) the frequency of unsuccessful ingestion by the predator, (2) whether the size of the prey predicts ingestion success, (3) whether the size of the predator predicts ingestion success, and (4) the relationship between prey and predator sizes in successful ingestion attempts. We found that nearly half (47.95%) of ingestion attempts by snakes on fledgling birds were unsuccessful, and no instances where unsuccessful ingestion caused the mortality of the snake. Attempts to consume smaller fledglings were as likely to be unsuccessful as attempts to swallow larger fledglings. However, snakes that successfully ingested fledglings were among the largest snakes in the population, and larger than average conspecifics attracted to endothermic prey. The smallest snakes that successfully ingested fledglings attained remarkably high relative prey mass values for their species, consuming prey weighing up to 79.9% of their own mass. Our study indicates that B. irregularis routinely predate prey that are too large for them to successfully ingest, which causes mortality to the prey but poses little risk to the predator. The potential reward for snakes in consuming oversized prey may outweigh the inherent risks, while instances of predation that do not result in consumption may have considerable impacts on prey populations.

Zooplankton link climate to capelin and polar cod in the Barents Sea

Capelin (Mallotus villosus) and polar cod (Boreogadus saida) hold a fundamental position in the Barents Sea ecosystem as consumers of zooplankton while serving as forage fish for the commercial and ecological key species Atlantic cod (Gadus morhua). The ongoing warming and Atlantification of the Barents Sea, along with increasing net primary production, makes previously inaccessible northern areas available as feeding grounds for capelin. The opposite effect is anticipated for the ice-dependent polar cod. The transport of Atlantic water with boreal plankton from the Norwegian Sea is important for sustaining biodiversity and production in the Barents Sea. A decline of the medium-sized mesozooplankton biomass to a low level during 2016 to 2022 coincided with a strongly decreasing summer volume transport with the Atlantic Current. The low biomass of medium-sized zooplankton observed in later years raises concern about the feeding conditions now experienced by the higher trophic levels.Both capelin and polar cod feed predominantly on lipid rich sub-Arctic and Arctic zooplankton species. We found a significant inverse relationship between capelin and mesozooplankton biomass and a clear dietary shift from smaller to larger predator size. Smaller capelin (<12 cm) contained a comparatively higher proportion of copepods, dominated by Calanus glacialis, followed by C. finmarchicus and Metridia longa (copepodite stages IV-VI). As the capelin grow, their diet switches towards larger zooplankton, primarily euphausiids (mainly Thysanoessa inermis). All age groups of polar cod fed heavily on pelagic amphipods (mostly Themisto libellula) in addition to copepods and euphausiids, and to some degree also on fish, thus displaying a higher trophic position than capelin. Capelin growth from age 1 to 2 was negatively associated with their abundance at age 2, but positively related to stomach fullness for 2-year-old fish, indicating density-dependent growth. While our study reveals interactions between capelin and zooplankton, such signals between polar cod and their prey were not evident.

Temperature alters the predator-prey size relationships and size-selectivity of Southern Ocean fish

A primary response of many marine ectotherms to warming is a reduction in body size, to lower the metabolic costs associated with higher temperatures. The impact of such changes on ecosystem dynamics and stability will depend on the resulting changes to community size-structure, but few studies have investigated how temperature affects the relative size of predators and their prey in natural systems. We utilise >3700 prey size measurements from ten Southern Ocean lanternfish species sampled across >10° of latitude to investigate how temperature influences predator-prey size relationships and size-selective feeding. As temperature increased, we show that predators became closer in size to their prey, which was primarily associated with a decline in predator size and an increase in the relative abundance of intermediate-sized prey. The potential implications of these changes include reduced top-down control of prey populations and a reduction in the diversity of predator-prey interactions. Both of these factors could reduce the stability of community dynamics and ecosystem resistance to perturbations under ocean warming.

Predator-prey interactions across hunting mode, spatial domain size, and habitat complexities.

Predator-prey interactions are a fundamental part of community ecology, yet the relative importance of consumptive and nonconsumptive effects (NCEs) (defined as a risk-induced response that alters prey fitness) has not been resolved. Theory suggests that the emergence and subsequent predominance of consumptive or NCEs depend on the given habitat's complexity as well as predator hunting mode and spatial domain sizes of both predator and prey, but their relative influence on the outcome of predator-prey interactions is unknown. We built agent-based models in NetLogo to simulate predator-prey interactions for three hunting modes-sit-and-wait, sit-and-pursue, and active-while concurrently simulating large versus small spatial domain sizes for both predators and prey. We studied (1) how hunting mode and spatial domain size interact to influence the emergence of consumptive or NCEs and (2) how, when NCEs do dominate, hunting mode and spatial domain separately or additively determine prey shifts in time, space, and habitat use. Our results indicate consumptive effects only dominate for active predators when prey habitat domains overlap completely with the predator's spatial domain and when sit-and-wait and sit-and-pursue predators and their prey both have large spatial domains. Prey are most likely to survive when they shift their time but most frequently shift their habitat. Our paper helps to better understand the underlying mechanisms that drive consumptive or NCEs to be most dominant.

Dynamic intraguild interactions between two sympatric and congeneric coccinellid species associated with aphids could explain their coexistence in citrus agroecosystems

Scymnus interruptus and Scymnus subvillosus (Coleoptera: Coccinellidae) are the most frequent aphid predators in Western Mediterranean citrus agroecosystems. Intraguild predation (IGP) between them would be expected, but how IGP might affect their coexistence and biological control function remains unknown. In this work, we assess the frequency of predator encounters in the field and investigate intraguild predation between these two predators in laboratory settings. Different field prey scenarios derived from the field observations were simulated with the two dominant aphid species in this agroecosystem, Aphis gossypii and Aphis spiraecola.Scymnus subvillosus and S. interruptus engaged in IGP but the magnitude and symmetry varied with the prey species and abundance. At high aphid densities, IGP was symmetric and weak, whereas, at low aphid densities, IGP was strong and very asymmetric, with S. interruptus taking the role of the intraguild predator. The developmental time of S. subvillosus was reduced when competing with S. interruptus at high extraguild prey densities. The adult size of both predators under weak IGP also increased even when the developmental time had been reduced.We predict that high aphid infestations in the spring would benefit S. subvillosus, while the strong and asymmetric IGP at low aphid infestations would hinder its coexistence with S. interruptus. Our results give a theoretical explanation to what is observed in the field: S. subvillosus is typically dominant during the high aphid infestations of the spring, whereas S. interruptus increases in relative dominance during the summer and fall when aphid abundance is much less.

Beyond the kill: The allometry of predation behaviours among large carnivores.

The costs of foraging can be high while also carrying significant risks, especially for consumers feeding at the top of the food chain. To mitigate these risks, many predators supplement active hunting with scavenging and kleptoparasitic behaviours, in some cases specializing in these alternative modes of predation. The factors that drive differential utilization of these tactics from species to species are not well understood. Here, we use an energetics approach to investigate the survival advantages of hunting, scavenging and kleptoparasitism as a function of predator, prey and potential competitor body sizes for terrestrial mammalian carnivores. The results of our framework reveal that predator tactics become more diverse closer to starvation, while the deployment of scavenging and kleptoparasitism is strongly constrained by the ratio of predator to prey body size. Our model accurately predicts a behavioural transition away from hunting towards alternative modes of predation with increasing prey size for predators spanning an order of magnitude in body size, closely matching observational data across a range of species. We then show that this behavioural boundary follows an allometric power-law scaling relationship where the predator size scales with an exponent nearing 3/4 with prey size, meaning that this behavioural switch occurs at relatively larger threshold prey body size for larger carnivores. We suggest that our approach may provide a holistic framework for guiding future observational efforts exploring the diverse array of predator foraging behaviours.

Predation on Baltic sea yolk-sac herring larvae (Clupea harengus) by the invasive ctenophore Mnemiopsis leidyi

Western Baltic spring spawning herring (Clupea harengus, L.) is a commercially important fish stock currently suffering a strong decline. Larval survival is essential for stock recruitment and can be substantially decreased by predation. The comb jelly Mnemiopsis leidyi A. Agassiz, 1865, is a lobate ctenophore which is invasive to the Baltic Sea and a known ichthyoplankton predator. However, predation on herring larvae in the Baltic Sea by M. leidyi has not been studied since its initial establishment in 2006. To address this knowledge gap, we conducted feeding experiments to investigate (1) the predation capability of M. leidyi on herring yolk-sac larvae, and (2) the influence of larval age, (3) predator size and (4) the presence of alternative prey on the clearance rate of M. leidyi on herring yolk-sac larvae. Our results showed that M. leidyi exhibited the ability to capture and digest herring larvae. The clearance rates of M. leidyi on herring larvae decreased with larval age and increased with predator size, while the presence of alternative prey had no effect on clearance rates. This finding suggests that M. leidyi can efficiently consume herring yolk-sac larvae under laboratory conditions. However, further investigations using mesocosm or field studies are necessary to evaluate the potential impact of M. leidyi on the mortality and recruitment of herring yolk-sac larvae under Baltic Sea field conditions.

Feeding ecology of two reef‐associated snappers (Lutjanus fulviflamma and L. fulvus): Influence of lunar phase on feeding activity

AbstractThe lunar phase is known to influence the spawning activity of some Lutjanus snappers, however, information on its influence on feeding activity is limited. In the present study, diet, feeding habit, and lunar periodicity of feeding activity on two reef‐associated sympatric snappers, blackspot snapper Lutjanus fulviflamma (n = 339) and blacktail snapper L. fulvus (n = 172), were investigated by stomach content analyses in the Yaeyama region (24°N, 124°E), southern Japan. Diets of the two snappers were similar and mainly consumed fishes, crabs, and shrimps. Relative volume of the stomach contents to body weight was compared by season, lunar day, and predator size using a generalized linear model. Larger individuals fed on larger fish prey and tended to show higher stomach fullness for both snappers. Periodic regression revealed that the lunar periodicity of the feeding activity is different between the two Lutjanus snappers. The feeding activity of L. fulviflamma increased around the spring tides of both new and full moons during a single lunar cycle. On the other hand, the feeding activity of L. fulvus increased only before the new moon but decreased before the full moon. Spawning of L. fulvus is known to occur only around the full moon, and enlarged gonads are considered to suppress the feeding activity of the species. Individuals with much stomach contents did not have large gonads for both snappers, and this supports the above supposition. Spawning and feeding activities are closely linked and simultaneous temporal analysis will enable a clearer understanding of the ecological role of these predators.

Hydra effect and global dynamics of predation with strong Allee effect in prey and intraspecific competition in predator

We consider a predator-prey system with strong Allee effect in prey and intraspecific competition in predator. We divide the parameter space into several mutually exclusive regions, and for each region we give a rather complete description of the global dynamics including equilibrium stability, Hopf bifurcation and its directions, existence of a heteroclinic orbit loop, a homoclinic orbit loop and limit cycles. In comparison with systems without the Allee effect in prey and systems without the intraspecific competition in predator, we find that the Allee effect in prey and the over-exploitation of the prey by the predator may drive the extinction of two species, but the intraspecific competition in the predator can generate “hydra effect” that regulates the population size of both predator and prey by suppressing the over-exploitation of prey, improving the probability of survivals of two species.

Predation and competition drive trait diversity across space and time.

Competition should play a key role in shaping community assembly and thereby local and regional biodiversity patterns. However, identifying its relative importance and effects in natural communities is challenging because theory suggests that competition can lead to different and even opposing patterns depending on the underlying mechanisms. Here, we have taken a different approach: rather than attempting to indirectly infer competition from diversity patterns, we compared trait diversity patterns in odonate (dragonfly and damselfly) communities across different spatial and temporal scales along a natural competition-predation gradient. At the local scale (within a community), we found that trait diversity increased with the size of top predators (from invertebrates to fish). This relationship is consistent with differences in taxonomic diversity, suggesting that competition reduces local trait diversity through competitive exclusion. Spatial (across communities) and temporal (within communities over time) trait variation peaked in communities with intermediate predators indicating that both high levels of competition or predation select for trait convergence of communities. This indicates that competition acts as a deterministic force that reduces trait diversity at the local, regional, and temporal scales, which contrasts with patterns at the taxonomic level. Overall, results from this natural experiment reveal how competition and predation interact to shape biodiversity patterns in natural communities across spatial and temporal scales and provide new insights into the underlying mechanisms.

Restored oyster reefs and living shorelines can augment predator trophic dynamics

Coastal habitat loss has led to declines in many higher trophic level predators. These declines can be mitigated through habitat restoration, which putatively enhances predator populations and trophic dynamics by creating foraging opportunities in reestablished habitat, but this lacks empirical support. Here, we assess the prediction restored coastal habitat supports sportfish feeding relationships similar to natural habitat, at restored oyster reefs (Crassostrea virginica) and living shoreline habitats in Florida, U.S.A. Stable isotopes and gut contents were analyzed from young sportfish (i.e. predatory fish targeted by anglers) collected at control and restored sites for up to 3 years. The influence of habitat features, predator size, and prey availability on carbon and nitrogen isotope values were examined using a model species (mangrove/gray snapper [Lutjanus griseus]). In summary, sportfish species had distinct isotopic values, consuming similar prey but in different proportions between habitats. Prey abundance and richness, and reef height were influential predictors of L. griseus stable isotope values, with restored reefs contributing to their diet more than controls according to Bayesian mixing models. The trophic niche area of L. griseus and their predominant prey achieved trophic equivalence between restored and natural oyster reefs within 1 year following restoration. Stabilized living shorelines attained trophic equivalency to natural shorelines, but may take longer to accrue prey for some species. These findings generate fundamental ecological knowledge and actionable science, including targets, timelines, and indicator species, that natural resource managers and restoration practitioners can use to assess trophic structure and success of coastal habitat restoration.

Environmental correlates of molluscan predator–prey body size in the northern Gulf of Mexico

AbstractThe Mississippi River watershed drains 40% of the continental United States, and the tremendous primary productivity in the adjacent north-central Gulf of Mexico has created one of the most extensive dead zones on Earth. In contrast, smaller watersheds deliver fewer nutrients to the northeastern gulf, and consequently, productivity is limited and hypoxia is uncommon. How has variation in primary productivity, oxygen availability, and sea-surface temperature affected coastal food webs? Here, we investigate environmental controls on the size of molluscan predators and prey in the northern Gulf of Mexico using Holocene death assemblages. Linear mixed models indicate that bivalve size and the frequency of drilling predation are affected by dissolved oxygen concentrations; drilling frequency declines with declining oxygen, whereas bivalve size increases. In contrast, sea-surface temperature is positively associated with the size of molluscan predators and prey. Net primary productivity contributes relatively little to predator or prey size, and predator-to-prey size ratios do not vary consistently with environmental conditions across the northern gulf. Larger bivalves in areas of oxygen limitation may be due to decreased predation pressure and, consequently, greater prey longevity. The larger size of bivalves and predatory gastropods in warmer waters may reflect enhanced growth under these conditions, provided dissolved oxygen concentrations exceed a minimum threshold. Holocene death assemblages can be used to test long-standing hypotheses regarding environmental controls on predator−prey body-size distributions through geologic time and provide baselines for assessing the ongoing effects of anthropogenic eutrophication and warming on coastal food webs.

Scaling relationships of maximal gape and prey size of snakes for an egg‐eating specialist (Dasypeltis gansi) and a dietary generalist (Pantherophis obsoletus)

AbstractThe size of both predators and prey can profoundly affect the foraging ecology of animals. This is especially true for snakes which consume prey whole. Although their gape imposes an anatomical limit on prey size, different snake species have a wide variety of prey types, prey sizes, and dietary breadth. To test whether a dietary specialist that only consumes bird eggs (Dasypeltis gansi) differed from a generalist that occasionally eats eggs (Pantherophis obsoletus), I quantified and compared the scaling relationships between overall size, cranial dimensions, and maximal gape and the orientation and mobility of relevant bones. Compared to P. obsoletus with a given overall size, D. gansi had maximal gape areas approximately 3–4 times greater and a significantly larger relative contribution to gape by the intermandibular (IM) soft tissues (50% vs. 19%). The greater distensibility of the IM soft tissues also allowed much greater lateral displacement of the distal end of the lower jaw in D. gansi versus P. obsoletus, but at maximal gape, the bones of these species had unexpectedly similar orientations in lateral view. The large gape of D. gansi was attained despite having a significantly shorter head than P obsoletus for a given snout–vent length. As a result of their large gape and more slender build, the predicted values of relative prey masses (RPM) for D. gansi at maximal gape vastly exceeded those of P. obsoletus for a given prey type. Although eggs are much stouter than rats, values of RPM at maximal gape for D. gansi eating eggs greatly exceeded those for P. obsoletus eating rats. Perhaps, Dasypeltis has the greatest size‐corrected gape and potential values of RPM (for a given prey shape) of any snake taxon as these values of D. gansi exceed those from all previously studied species with similar data.

Feeding habits of Boana raniceps (Cope, 1862) in three mountains of Brazilian semiarid

Studying the trophic ecology of animals helps us understand their life history, their relationship with the environment and other species, and their role in ecosystems. In this sense, we describe the feeding habits of the hyalid frog Boana raniceps in three high-altitude mountain ranges of Northeastern Brazil, investigating intersex differences in the diet and the relationship between the size with the volume of prey consumed. Furthermore, we investigated prey-predator interactions in the Boana genus with an ecological network approach. We analyzed the stomach contents of 62 B. raniceps specimens collected in three mountains in the state of Ceará (Northeastern Brazil) and consulted data available in the literature for information on the diet of other Boana species. We identied 82 prey items distributed in eleven categories. Overall, there were no differences in the composition of B. raniceps diet among the three mountains. Although males and females shared the majority of prey items consumed, they tended to consume prey volumetrically differently, and predator size did not influence prey volume. In addition, predator-prey interactions in the genus Boana revealed low modularity, complementary specialization, and nestedness. Therefore, species of the genus Boana follow the general pattern for the diet of most Brazilian frog species (generalist and opportunistic habits), being likely influenced by the availability of prey in the habitat. Overall, the present study constitutes a complete review of the prey items consumed by the genus Boana in Brazil, describing the general pattern of anuran-prey networks in these hylids.

The risks of standing out to mate: Predation of Hylodes cardosoi by Bothrops jararaca

AbstractVocalization, visual and chemical signals are courtship behaviours of anurans that may expose them to the risk of predation. Here, we described a predation event in which a population of the torrent frog Hylodes cardosoi was in intense courtship behaviour and one individual was caught by a specimen of the pitviper Bothrops jararaca. The predation event was recorded in a region of Atlantic Forest, Paraná, Brazil. We hypothesized that the pitviper was ambush hunting and captured a female frog that was attracted by the vocalization of a nearby male. Predatory interactions are important ecological factors driving the evolution and population size of both prey and predator. This report increases the prey richness described for B. jararaca and also extends the known geographic distribution of H. cardosoi. Our observation contributes to knowledge of the natural history of the species involved.

Length–weight relationship and seasonal variations in diet composition of whiting (Merlangius merlangus) in the South-eastern Black Sea

ABSTRACT The sex ratio, length–weight relationship (LWR) and diets based on stomach contents of whiting (Merlangius merlangus) were investigated in the south-eastern Black Sea, Turkey. A total of 3507 females (7.5–24.0 cm), 1602 males (9.4–20.0 cm), and 78 unidentified sex (5.5–16.5 cm) whiting were caught during monthly sampling from February to December 2017. The sex ratio was dominated by females, and their ratio (♀:♂, 1:0.46) significantly deviated from 1:1. The LWR indicated a negative allometric growth for males, while females had a positive allometric growth pattern. The stomach content analysis based on the relative importance index (IRI%) indicated exclusively piscivorous diets dominant by Sprattus sprattus and Engraulis encrasicolus made up more than 91 IRI% of the total diets of M. merlangus. The modified Costello-Amundsen’s graphical analyses evinced the specialized feeding strategy of M. merlangus throughout this study. The contribution of these two preys to the diets of M. merlangus showed considerable seasonal variations that were totally dependent on their abundance. Sprattus sprattus contributed to more than 98% of the total diets during June, July and August, while in the following months, E. encrasicolus appeared to take its position. Based on fish size, a general trend of a rise in prey diversity was found with increasing fish size. Also, the contribution of S. sprattus tended to decrease with increasing predator size, which is replaced by a rise in E. encrasicolus contribution. Hence, larger M. merlangus predominantly fed on E. encrasicolus while smaller size predators preferred to feed on S. sprattus.

Using natricine snakes to test how prey type and size affect predatory behaviors and performance.

Predation is a complex process for which behavior, morphology, and size of both predator and prey can affect the success and effectiveness of the predator. For predators such as snakes that swallow prey whole, gape ultimately limits prey size, but the behaviors used to select, capture, and consume prey and attributes of the prey can also affect maximal prey size. For example, swallowing live, struggling prey is difficult, but using coiling or envenomation to restrain or kill prey has evolved repeatedly in snakes. To test the potential benefits of these behaviors, we manipulated the type and size of prey, and determined how stereotyped predatory behavior was in a snake species (Liodytes rigida) that uses both coiling and envenomation to restrain and immobilize its formidable prey of crayfish. We also studied a close relative (Liodytes pygaea) that eats fish and salamanders to gain insights into the evolution of these traits. For L. rigida, envenomation of hard-shell crayfish via their soft underside was very stereotyped (100% of feedings). Envenomation of soft-shell crayfish was less frequent (59% of feedings) but became more likely both with increased relative prey size and increased time after molt (hardness). L. rigida coiled more for hard-shell than soft-shell crayfish (77% vs. 30%). The probability of coiling was unaffected by prey size, but it increased with increased time after molt for the soft-shell crayfish. Liodytes rigida waited to swallow crayfish until they were completely immobile in 75% and 37% of the feedings with hard- and soft-shelled crayfish, respectively. Even with large prey L. pygaea never used coiling or envenomation, whereas previous studies of L. alleni, the sister species of L. rigida, observed non-lethal coiling without envenomation when eating hard-shell crayfish. Our findings for the Liodytes clade of three species suggest that coiling evolved ancestral to the crayfish specialists (L. alleni; L. rigida), and envenomation by L. rigida subsequently evolved as an additional means of subduing formidable prey. The proximate benefits observed for coiling and envenomation in L. rigida support the evolutionary scenario that both traits evolved to enhance the feeding performance for more formidable prey.

Variation in body size drives spatial and temporal variation in lobster-urchin interaction strength.

How strongly predators and prey interact is both notoriously context dependent and difficult to measure. Yet across taxa, interaction strength is strongly related to predator size, prey size and prey density, suggesting that general cross-taxonomic relationships could be used to predict how strongly individual species interact. Here, we ask how accurately do general size-scaling relationships predict variation in interaction strength between specific species that vary in size and density across space and time? To address this question, we quantified the size and density dependence of the functional response of the California spiny lobster Panulirus interruptus, foraging on a key ecosystem engineer, the purple sea urchin Strongylocentrotus purpuratus, in experimental mesocosms. Based on these results, we then estimated variation in lobster-urchin interaction strength across five sites and 9 years of observational data. Finally, we compared our experimental estimates to predictions based on general size-scaling relationships from the literature. Our results reveal that predator and prey body size has the greatest effect on interaction strength when prey abundance is high. Due to consistently high urchin densities in the field, our simulations suggest that body size-relative to density-accounted for up to 87% of the spatio-temporal variation in interaction strength. However, general size-scaling relationships failed to predict the magnitude of interactions between lobster and urchin; even the best prediction from the literature was, on average, an order of magnitude (+18.7×) different than our experimental predictions. Harvest and climate change are driving reductions in the average body size of many marine species. Anticipating how reductions in body size will alter species interactions is critical to managing marine systems in an ecosystem context. Our results highlight the extent to which differences in size-frequency distributions can drive dramatic variation in the strength of interactions across narrow spatial and temporal scales. Furthermore, our work suggests that species-specific estimates for the scaling of interaction strength with body size, rather than general size-scaling relationships, are necessary to quantitatively predict how reductions in body size will alter interaction strengths.

Environmental Controls on Predator and Prey Body Size in the Northern Gulf of Mexico

The Mississippi River delivers vast quantities of nutrient-rich freshwater to the northern Gulf of Mexico, fueling primary productivity in the coastal zone. Aerobic decomposition of these phytoplankton blooms has resulted in one of the most extensive dead zones on Earth. In contrast, primary productivity and hypoxia are more limited in the northeastern Gulf, where coastal environments are fed by smaller watersheds. How do environmental factors such as primary productivity, oxygen availability, and sea surface temperature shape coastal food webs? Here, we investigate environmental correlates of predator and prey body size in benthic mollusks using Holocene death assemblages. Results of linear mixed effects models indicate that bivalve size and the frequency of drilling predation are both influenced by dissolved oxygen concentrations; bivalve size increases and drilling frequency decreases with declining oxygen levels. Sea surface temperature is positively associated with predator and prey size, whereas net primary productivity has little effect on the size of predators or prey. Predator-to-prey size ratios were not significantly associated with any of the environmental factors considered. Larger bivalves found in oxygen-limited areas may be due to decreased predation pressure, resulting in greater prey longevity. Warmer waters with sufficient dissolved oxygen may also provide suitable growth conditions to increase the size of bivalves and predatory gastropods. Holocene death assemblages can be used to test long-standing hypotheses regarding environmental controls on predator-prey body size distributions through geologic time and provide baselines for assessing the ongoing effects of anthropogenic eutrophication and warming on coastal food webs.