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Within oligotrophic ecosystems, resource limitations coupled with interspecific variation in morphology, physiology, and life history traits may lead to niche partitioning among species. How generalist predators partition resources and their mechanisms, however, remain unclear across many ecosystems. We quantified niche partitioning among upper trophic level coastal and estuarine species: American alligators (Alligator mississippiensis), bull sharks (Carcharhinus leucas), common bottlenose dolphins (Tursiops truncatus), common snook (Centropomus undecimalis), and Atlantic tarpon (Megalops atlanticus) in the Shark River Estuary of the Florida Coastal Everglades, USA using acoustic telemetry, stable isotope analysis, and visual surveys, combined with published diet and life history demographic information. Spatial and isotopic niche overlap occurred among most species, with variability in partitioning among interspecific interactions. However, seasonal variability in habitat use, movements patterns, and trophic interactions may promote coexistence within this resource‐limited estuary. Beyond guild‐level niche partitioning, predators within the Shark River Estuary also exhibit partitioning within species through individual specializations and divergent phenotypes, which may lead to intraspecific variability in niche overlap with other predators. Niche differentiation expressed across multiple organizational levels (i.e., populations and communities) coupled with behavioral plasticity among predators in oligotrophic ecosystems may promote high species diversity despite resource limitations, which may be important when species respond to natural and human‐driven environmental change.

Predators continue to be harvested unsustainably throughout most of the Earth's ecosystems. Recent research demonstrates that the functional loss of predators could have far-reaching consequences on carbon cycling and, by implication, our ability to ameliorate climate change impacts. Yet the influence of predators on carbon accumulation and preservation in vegetated coastal habitats (that is, salt marshes, seagrass meadows and mangroves) is poorly understood, despite these being some of the Earth's most vulnerable and carbon-rich ecosystems. Here we discuss potential pathways by which trophic downgrading affects carbon capture, accumulation and preservation in vegetated coastal habitats. We identify an urgent need for further research on the influence of predators on carbon cycling in vegetated coastal habitats, and ultimately the role that these systems play in climate change mitigation. There is, however, sufficient evidence to suggest that intact predator populations are critical to maintaining or growing reserves of 'blue carbon' (carbon stored in coastal or marine ecosystems), and policy and management need to be improved to reflect these realities.

Foraging animals must often balance the conflicting demands of finding food and avoiding predators. Temporal variation in predation risk is expected to influence how animals allocate time to these behaviours. Counterintuitively, the proportion of time spent foraging during both high– and low–risk periods should increase with increasing time exposed to high risk. We tested this prediction using intertidal marine snails (Littorinaspp.) that were exposed to temporal variation in perceived predation risk from crabs (Cancer productusand Cancer magister). Our results were consistent with those predicted for high–risk, but not low–risk, periods. During high–risk periods, a greater number of snails foraged (versus those that left the water or remained in their shells) as time at high perceived risk increased. For low–risk periods, there was no relationship between the number of snails foraging and time at high risk. This might be due to snails in all treatments foraging maximally in the low–risk periods. As a consequence, the difference in the number of snails foraging between high– and low–risk periods decreased with increasing time subject to high risk. These results indicate that the commonly used protocol of exposing foragers to a single pulse of heightened risk might tend to overestimate their typical investment in anti–predator behaviour.

Large brain size in mammals has been related to the number and complexity of social relationships, particularly social alliances within groups. The largest within–group male alliance known outside of humans is found in a social network (>400) of Indian Ocean bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia. Members of this dolphin ‘super–alliance’ cooperate against other alliances over access to females. Males within the super–alliance form temporary trios and occasionally pairs in order to consort with individual females. The frequent switching of alliance partners suggests that social relationships among males within the super–alliance might be relatively simple and based on an ‘equivalence rule’, thereby allowing dolphins to form large alliances without taxing their ‘social intelligence’. The equivalence model predicts that the 14 males in the super–alliance should not exhibit differences in alliance stability or partner preferences. However, data from 100 consortships do not support the equivalence hypothesis. The 14 males exhibited striking differences in alliance stability and partner preferences suggesting that the super–alliance has a complex internal structure. Further, within the super–alliance, alliance stability correlates with consortship rate, suggesting that differentiated relationships within the super–alliance are based on competition for access to females.

The importance of interactions between sharks and cetaceans has been a subject of much conjecture, but few studies have addressed these interactions. Sharks (order Selachii) have been hypothesized to be important predators on dolphins and porpoises (suborder Odontoceti). Unfortunately, there are often few data to back up claims that certain shark species are major threats to cetaceans. To help identify potential shark predators in specific locations, available data on interactions with odontocetes for all shark species that may include cetaceans in their diet are reviewed. Shark species are categorized into groups based on predatory interactions with dolphins and porpoises (regular predators, occasional predators, potential predators, ectoparasites and insufficient data). Several shark species that have been overlooked in the cetacean literature are identified as potentially important predators while others that have been suspected to be important predators are probably at most occasional predators. How shark predation can influence dolphin populations, habitat use, group size and behaviour is discussed. How risk of shark predation can vary with habitat attributes in both nearshore and pelagic waters is also discussed. Predator–prey interactions have been the focus of most studies of shark–dolphin interaction, but competitive interactions may also occur. The first analysis of shark–dolphin dietary overlap is presented, which shows it to be significant between common dolphins and several species of sharks, including species that prey upon these dolphins.