Showing papers by "Ashley J. W. Ward published in 2020"

Quantifying the structure and dynamics of fish shoals under predation threat in three dimensions

Abstract: Detailed quantifications of how predators and their grouping prey interact in three dimensions (3D) remain rare. Here we record the structure and dynamics of fish shoals (Pseudomugil signifer) in 3 ...

Social Recognition and Social Attraction in Group-Living Fishes

Abstract: Social aggregation is a widespread and important phenomenon among fishes. Understanding the questions of why and how aggregations form and are subsequently maintained is a central goal for behavioural ecologists. Research in this field has shown that aggregations are typically structured, non-random associations. This indicates that fish are able to differentiate between potential group-mates and that this ability mediates their association preferences, and, ultimately, the composition of their groups. In this review, we examine the characteristics that influence the expression of social attraction among fishes, before going on to describe the recognition mechanisms that underpin social attraction. Finally, we highlight a number of outstanding questions in the field with a view to generating a more complete understanding of social aggregation in fishes.

To clean or not to clean: Cleaning mutualism breakdown in a tidal environment.

Abstract: The dynamics and prevalence of mutualistic interactions, which are responsible for the maintenance and structuring of all ecological communities, are vulnerable to changes in abiotic and biotic environmental conditions. Mutualistic outcomes can quickly shift from cooperation to conflict, but it unclear how resilient and stable mutualistic outcomes are to more variable conditions. Tidally controlled coral atoll lagoons that experience extreme diurnal environmental shifts thus provide a model from which to test plasticity in mutualistic behavior of dedicated (formerly obligate) cleaner fish, which acquire all their food resources through client interactions. Here, we investigated cleaning patterns of a model cleaner fish species, the bluestreak wrasse (Labroides dimidiatus), in an isolated tidal lagoon on the Great Barrier Reef. Under tidally restricted conditions, uniquely both adults and juveniles were part‐time facultative cleaners, pecking on Isopora palifera coral. The mutualism was not completely abandoned, with adults also wandering across the reef in search of clients, rather than waiting at fixed site cleaning stations, a behavior not yet observed at any other reef. Contrary to well‐established patterns for this cleaner, juveniles appeared to exploit the system, by biting (“cheating”) their clients more frequently than adults. We show for the first time, that within this variable tidal environment, where mutualistic cleaning might not represent a stable food source, the prevalence and dynamics of this mutualism may be breaking down (through increased cheating and partial abandonment). Environmental variability could thus reduce the pervasiveness of mutualisms within our ecosystems, ultimately reducing the stability of the system.

Locomotion and habituation to novel experimental environments in a social fish species

Abstract: The response of animals to novel environments forms the basis of open field tests, an assay extensively used in the study of animal behaviour. However, to assess an animal’s routine behaviour or measure their response to novel environments, researchers must provide enough time for proper exploration and habituation. Unfortunately, no study has ever explicitly characterized the habituation process, except on isolated individuals, which represents an unusual situation for many social species. We analysed the movement characteristics and group-level dynamics of a shoaling fish species (Gambusia holbrooki) in an open-field arena for 1.5 h. We tested groups of 4 fish with varying sex ratios and found that behaviour changed over time with exploratory behaviour followed by a decreasing then plateauing trend, which only stabilised after 29 min. This movement pattern was consistent across all different sex ratios, however, female-skewed groups showed higher levels of activity during the first few minutes. Finally, median nearest neighbour distance was initially low before increasing and finally stabilising at around 9 min (with some exceptions) following the introduction of fish to the arena.