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1. Spatial and temporal variation in the occurrence of bottlenose dolphins in the Chesapeake Bay, USA, using citizen science sighting data

   https://doi.org/10.1371/journal.pone.0251637  

   Rodriguez, Lauren Kelly ; Fandel, Amber D. ; Colbert, Benjamin R. ; Testa, Jamie C. ; Bailey, Helen ( May 2021 , PLOS ONE)

   Caballero, Susana (Ed.)

   Bottlenose dolphins ( Tursiops truncatus ) are migratory marine mammals that live in both open-ocean and coastal habitats. Although widely studied, little is known about their occurrence patterns in the highly urbanized estuary of the Chesapeake Bay, USA. The goal of this study was to establish the spatial and temporal distribution of bottlenose dolphins throughout this large estuarine system and use statistical modeling techniques to determine how their distribution relates to environmental factors. Three years (April-October 2017–2019) of dolphin sighting reports from a citizen-science database, Chesapeake DolphinWatch, were analyzed. The dolphins had a distinct temporal pattern, most commonly sighted during summer months, peaking in July. This pattern of observed occurrence was confirmed with systematic, passive acoustic detections of dolphin echolocation clicks from local hydrophones. Using spatially-exclusive Generalized Additive Models (GAM), dolphin presence was found to be significantly correlated to spring tidal phase, warm water temperature (24–30°C), and salinities ranging from 6–22 PPT. We were also able to use these GAMs to predict dolphin occurrence in the Bay. These predictions were statistically correlated to the actual number of dolphin sighting reported to Chesapeake DolphinWatch during that time. These models for dolphin presence can be implemented as a predictive tool for species occurrence and inform management of this protected species within the Chesapeake Bay. 

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2. Predator‐induced defences under tropicalisation: A biogeographic approach

   https://doi.org/10.1111/jbi.14716  

   Fenberg, Phillip B. ; Beas‐Luna, Rodrigo ; Igić, Boris ; MacLean, Moira A. ; Paz‐García, David A. ; Raimondi, Peter T. ; Sones, Jacqueline L. ; Zarzyczny, Karolina M. ; Sanford, Eric ( September 2023 , Journal of Biogeography)

   The biogeography of predator‐induced defences is an understudied area of predator–prey dynamics. Range overlap with predators that induce the response and local demographics (e.g., prey abundances) are likely to be important factors for determining the biogeographic distribution of induced defences within species. However, with climate warming, range‐expanding warm‐water predators are increasingly preying upon temperate species. This is a consequence of a wider phenomenon known as tropicalisation. We aim to determine: (i) if individuals of a temperate barnacle with induced defences (‘bent morphs’) are primarily present where they co‐occur with range‐expanding warm‐water predators (muricid snails) and, (ii) if bent morphs are size‐structured within populations.

   North‐eastern Pacific rocky intertidal zone (~26–40° N).

   Tetraclita rubescens(Nilsson‐Cantell, 1931), Balanomorpha.

   We use photoquadrats from sites across the range ofT. rubescensto determine the biogeographic distribution of populations with bent morphs and to assess size‐structure. We use a combination of field surveys, literature, and museum occurrences to assess range overlap between cool and warm‐water predators ofT. rubescensand their association with populations with bent morphs and abundance patterns ofT. rubescens.

   Bent morphs are commonly found within the equatorward portion of the species' range (where abundances are highest), in populations overlapping with range‐expanding warm‐water predators. Bent morphs primarily occur within the smaller size classes.

   To be partly resilient to the effects of tropicalisation, temperate prey must acclimatise/adapt to altered predator–prey dynamics. Predator‐induced defences are one way to do this. We show that bent morphs within a temperate prey species (T. rubescens) are largely restricted to populations that overlap with large‐bodied and range‐expanding warm‐water predators. This is evidence for the partial resilience ofT. rubescensto tropicalisation and provides the rationale for further exploration of the eco‐evolutionary consequences of tropicalisation in this study system and others.

    

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3. The reliability of pigment pattern‐based identification of wild bottlenose dolphins

   https://doi.org/10.1111/mms.12440  

   Bichell, Lena_Marie_Vetters ; Krzyszczyk, Ewa ; Patterson, Eric_M ; Mann, Janet ( September 2017 , Marine Mammal Science)

   Long‐term studies often rely on natural markings for individual identification across time. The primary method for identification in small cetaceans relies on dorsal fin shape, scars, and other natural markings. However, dorsal fin markings can vary substantially over time and the dorsal fin can become unrecognizable after an encounter with a boat or shark. Although dorsal fins have the advantage in that they always break the water surface when the cetacean breathes, other physical features, such as body scars and pigmentation patterns can supplement. The goal of this study was to explore the use of dorso‐lateral pigment patterns to identify wild bottlenose dolphins. We employed photographic pigment matching tests to determine if pigmentation patterns showed (1) longitudinal consistency and (2) bilateral symmetry using a 30 yr photographic database of bottlenose dolphins (Tursiops aduncus). We compared experienced dolphin researchers and inexperienced undergraduate student subjects in their ability to accurately match images. Both experienced and inexperienced subjects correctly matched dolphin individuals at a rate significantly above chance, even though they only had 10 s to make the match. These results demonstrate that pigment patterns can be used to reliably identify individual wild bottlenose dolphins, and likely other small cetacean species at other sites.

    

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4. Predator hunting modes and predator–prey space games

   https://doi.org/10.1111/eth.12998  

   Luttbeg, Barney ; Hammond, John_I ; Brodin, Tomas ; Sih, Andrew ; Wright, ed., Jonathan ( December 2019 , Ethology)

   Predators and prey are often engaged in a game where their expected fitnesses are affected by their relative spatial distributions. Game models generally predict that when predators and prey move at similar temporal and spatial scales that predators should distribute themselves to match the distribution of the prey's resources and that prey should be relatively uniformly distributed. These predictions should better apply to sit‐and‐pursue and sit‐and‐wait predators, who must anticipate the spatial distributions of their prey, than active predators that search for their prey. We test this with an experiment observing the spatial distributions and estimating the causes of movements between patches for Pacific tree frog tadpoles (Pseudacris regilla), a sit‐and‐pursue dragonfly larvae predator (Rhionaeschna multicolor), and an active salamander larval predator (Ambystoma tigrinum mavortium) when a single species was in the arena and when the prey was with one of the predators. We find that the sit‐and‐pursue predator favors patches with more of the prey's algae resources when the prey is not in the experimental arena and that the prey, when in the arena with this predator, do not favor patches with more resources. We also find that the active predator does not favor patches with more algae and that prey, when with an active predator, continue to favor these higher resource patches. These results suggest that the hunting modes of predators impact their spatial distributions and the spatial distributions of their prey, which has potential to have cascading effects on lower trophic levels.

    

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5. The Pelagic Species Trait Database, an open data resource to support trait-based ocean research

   https://doi.org/10.1038/s41597-023-02689-9  

   Gleiber, Miram R. ; Hardy, Natasha A. ; Roote, Zachary ; Krug-MacLeod, Alana M. ; Morganson, Caitlin J. ; Tandy, Zackary ; George, Iris ; Matuch, Cindy ; Brookson, Cole B. ; Daly, Elizabeth A. ; et al ( January 2024 , Scientific Data)

   Trait-based frameworks are increasingly used for predicting how ecological communities respond to ongoing global change. As species range shifts result in novel encounters between predators and prey, identifying prey ‘guilds’, based on a suite of shared traits, can distill complex species interactions, and aid in predicting food web dynamics. To support advances in trait-based research in open-ocean systems, we present the Pelagic Species Trait Database, an extensive resource documenting functional traits of 529 pelagic fish and invertebrate species in a single, open-source repository. We synthesized literature sources and online resources, conducted morphometric analysis of species images, as well as laboratory analyses of trawl-captured specimens to collate traits describing 1) habitat use and behavior, 2) morphology, 3) nutritional quality, and 4) population status information. Species in the dataset primarily inhabit the California Current system and broader NE Pacific Ocean, but also includes pelagic species known to be consumed by top ocean predators from other ocean basins. The aim of this dataset is to enhance the use of trait-based approaches in marine ecosystems and for predator populations worldwide.

    

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