Of wolves and bears: Seasonal drivers of interference and exploitation competition between apex predators

AbstractUnderstanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

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Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks

Scientific Reports ◽

10.1038/s41598-021-89903-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Aaron B. Carlisle ◽

Elizabeth Andruszkiewicz Allan ◽

Sora L. Kim ◽

Lauren Meyer ◽

Jesse Port ◽

...

Keyword(s):

Trophic Ecology ◽

Foraging Ecology ◽

Isotope Analysis ◽

Environmental Dna ◽

Small Sample ◽

Apex Predators ◽

Central Pacific ◽

Chemical Tracers ◽

Important Prey ◽

Tracer Techniques

AbstractThe Cookiecutter shark (Isistius brasiliensis) is an ectoparasitic, mesopelagic shark that is known for removing plugs of tissue from larger prey, including teleosts, chondrichthyans, cephalopods, and marine mammals. Although this species is widely distributed throughout the world’s tropical and subtropical oceanic waters, like many deep-water species, it remains very poorly understood due to its mesopelagic distribution. We used a suite of biochemical tracers, including stable isotope analysis (SIA), fatty acid analysis (FAA), and environmental DNA (eDNA), to investigate the trophic ecology of this species in the Central Pacific around Hawaii. We found that large epipelagic prey constituted a relatively minor part of the overall diet. Surprisingly, small micronektonic and forage species (meso- and epipelagic) are the most important prey group for Cookiecutter sharks across the studied size range (17–43 cm total length), with larger mesopelagic species or species that exhibit diel vertical migration also being important prey. These results were consistent across all the tracer techniques employed. Our results indicate that Cookiecutter sharks play a unique role in pelagic food webs, feeding on prey ranging from the largest apex predators to small, low trophic level species, in particular those that overlap with the depth distribution of the sharks throughout the diel cycle. We also found evidence of a potential shift in diet and/or habitat with size and season. Environmental DNA metabarcoding revealed new prey items for Cookiecutter sharks while also demonstrating that eDNA can be used to identify recent prey in stomachs frozen for extended periods. Integrating across chemical tracers is a powerful tool for investigating the ecology of elusive and difficult to study species, such as meso- and bathypelagic chondrichthyans, and can increase the amount of information gained from small sample sizes. Better resolving the foraging ecology of these mesopelagic predators is critical for effective conservation and management of these taxa and ecosystems, which are intrinsically vulnerable to overfishing and exploitation.

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Camera Trapping to Assess Status and Composition of Mammal Communities in a Biodiversity Hotspot in Myanmar

Animals ◽

10.3390/ani11030880 ◽

2021 ◽

Vol 11 (3) ◽

pp. 880

Author(s):

Giacomo Cremonesi ◽

Francesco Bisi ◽

Lorenzo Gaffi ◽

Thet Zaw ◽

Hla Naing ◽

...

Keyword(s):

Human Disturbance ◽

Habitat Degradation ◽

Single Species ◽

Wildlife Trade ◽

Ecosystem Functions ◽

Occupancy Models ◽

Apex Predators ◽

Disturbed Area ◽

The Status ◽

Mammal Communities

Tropical forests comprise a critically impacted habitat, and it is known that altered forests host a lower diversity of mammal communities. In this study, we investigated the mammal communities of two areas in Myanmar with similar environmental conditions but with great differences in habitat degradation and human disturbance. The main goal was to understand the status and composition of these communities in an understudied area like Myanmar at a broad scale. Using camera trap data from a three-year-long campaign and hierarchical occupancy models with a Bayesian formulation, we evaluated the biodiversity level (species richness) and different ecosystem functions (diet and body mass), as well as the occupancy values of single species as a proxy for population density. We found a lower mammal diversity in the disturbed area, with a significantly lower number of carnivores and herbivores species. Interestingly, the area did not show alteration in its functional composition. Almost all the specific roles in the community were present except for apex predators, thus suggesting that the effects of human disturbance are mainly effecting the communities highest levels. Furthermore, two species showed significantly lower occupancies in the disturbed area during all the monitoring campaigns: one with a strong pressure for bushmeat consumption and a vulnerable carnivore threatened by illegal wildlife trade.

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Mechanisms Involved in Interspecific Communication between Wine Yeasts

Foods ◽

10.3390/foods10081734 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1734

Author(s):

Ana Mencher ◽

Pilar Morales ◽

Jordi Tronchoni ◽

Ramon Gonzalez

Keyword(s):

Alcoholic Fermentation ◽

Yeast Species ◽

Interspecific Interactions ◽

Interference Competition ◽

Weighted Average ◽

Starter Cultures ◽

Simple Consequence ◽

Wine Yeasts ◽

Exploitation Competition ◽

Metabolic Intermediates

In parallel with the development of non-Saccharomyces starter cultures in oenology, a growing interest has developed around the interactions between the microorganisms involved in the transformation of grape must into wine. Nowadays, it is widely accepted that the outcome of a fermentation process involving two or more inoculated yeast species will be different from the weighted average of the corresponding individual cultures. Interspecific interactions between wine yeasts take place on several levels, including interference competition, exploitation competition, exchange of metabolic intermediates, and others. Some interactions could be a simple consequence of each yeast running its own metabolic programme in a context where metabolic intermediates and end products from other yeasts are present. However, there are clear indications, in some cases, of specific recognition between interacting yeasts. In this article we discuss the mechanisms that may be involved in the communication between wine yeasts during alcoholic fermentation.

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Contaminants in indigenous harvests of apex predators: The Tasmanian Short-tailed Shearwater as a case study

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2013.05.021 ◽

2013 ◽

Vol 95 ◽

pp. 78-82 ◽

Cited By ~ 5

Author(s):

Jennifer L. Lavers ◽

Alexander L. Bond

Keyword(s):

Apex Predators

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Loss of predation risk from apex predators can exacerbate marine tropicalization caused by extreme climatic events

Journal of Animal Ecology ◽

10.1111/1365-2656.13424 ◽

2021 ◽

Author(s):

Robert J. Nowicki ◽

Jordan A. Thomson ◽

James W. Fourqurean ◽

Aaron J. Wirsing ◽

Michael R. Heithaus

Keyword(s):

Predation Risk ◽

Apex Predators ◽

Extreme Climatic Events

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Diffusion modeling reveals effects of multiple release sites and human activity on a recolonizing apex predator

Movement Ecology ◽

10.1186/s40462-021-00270-w ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Joseph M. Eisaguirre ◽

Perry J. Williams ◽

Xinyi Lu ◽

Michelle L. Kissling ◽

William S. Beatty ◽

...

Keyword(s):

Human Activity ◽

Residence Time ◽

Prey Availability ◽

Commercial Fishing ◽

Apex Predators ◽

Sea Otters ◽

Southeast Alaska ◽

Bayesian Hierarchical ◽

Factors Influencing ◽

Multiple Population

Abstract Background Reintroducing predators is a promising conservation tool to help remedy human-caused ecosystem changes. However, the growth and spread of a reintroduced population is a spatiotemporal process that is driven by a suite of factors, such as habitat change, human activity, and prey availability. Sea otters (Enhydra lutris) are apex predators of nearshore marine ecosystems that had declined nearly to extinction across much of their range by the early 20th century. In Southeast Alaska, which is comprised of a diverse matrix of nearshore habitat and managed areas, reintroduction of 413 individuals in the late 1960s initiated the growth and spread of a population that now exceeds 25,000. Methods Periodic aerial surveys in the region provide a time series of spatially-explicit data to investigate factors influencing this successful and ongoing recovery. We integrated an ecological diffusion model that accounted for spatially-variable motility and density-dependent population growth, as well as multiple population epicenters, into a Bayesian hierarchical framework to help understand the factors influencing the success of this recovery. Results Our results indicated that sea otters exhibited higher residence time as well as greater equilibrium abundance in Glacier Bay, a protected area, and in areas where there is limited or no commercial fishing. Asymptotic spread rates suggested sea otters colonized Southeast Alaska at rates of 1–8 km/yr with lower rates occurring in areas correlated with higher residence time, which primarily included areas near shore and closed to commercial fishing. Further, we found that the intrinsic growth rate of sea otters may be higher than previous estimates suggested. Conclusions This study shows how predator recolonization can occur from multiple population epicenters. Additionally, our results suggest spatial heterogeneity in the physical environment as well as human activity and management can influence recolonization processes, both in terms of movement (or motility) and density dependence.

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Feeding patterns of two sympatric shark predators in coastal ecosystems of an oceanic island

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2016-0105 ◽

2017 ◽

Vol 74 (2) ◽

pp. 216-227 ◽

Cited By ~ 6

Author(s):

Clément Trystram ◽

Karyne M. Rogers ◽

Marc Soria ◽

Sébastien Jaquemet

Keyword(s):

Trophic Ecology ◽

Dietary Habits ◽

Stomach Contents ◽

Nitrogen Isotope ◽

Oceanic Island ◽

Apex Predators ◽

Coastal Habitat ◽

Galeocerdo Cuvier ◽

Carcharhinus Leucas ◽

Bull Shark

Stomach contents and stable carbon and nitrogen isotope analyses (δ13C and δ15N) were used to investigate the trophic ecology of two apex predators, tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas), from Reunion Island to describe their dietary habits at both the population and individual levels. In this oceanic island, the tiger and bull sharks were more piscivorous and teutophagous than noted in previous research from other localities. The δ13C values suggested that bull sharks depended on more neritic organic matter sources than tiger sharks, confirming a coastal habitat preference for bull sharks. Moreover, the total length of the bull shark influenced δ13C values, with smaller individuals being more coastal than larger individuals. All indicators suggest that there is a higher degree of similarity between individual tiger sharks compared with the more heterogeneous bull shark population, which is composed of individuals who specialize on different prey. These results suggest that the two species have different functions in these coastal habitats, and thus, they must be considered independently in terms of conservation and management.

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