Hurricane impacts on the foraging patterns of bottlenose dolphins Tursiops truncatus in Mississippi Sound

Abstract

Acute catastrophic events, such as hurricanes, have various degrees of impact on marine mammal populations. Although changes in environmental conditions of affected areas have been examined for many storms, little attention has been given to the ecological effects on top-level predators. A longitudinal study on bottlenose dolphin Tursiops truncatus behavior and distribution in Mississippi Sound has been ongoing since 2003, allowing the unique opportunity to examine the impacts of the passage of Hurricane Katrina on this coastal dolphin population. Previous research showed an increase in reproductive rates within this population following Hurricane Katrina, most likely due to an increase in prey density following the sharp decline in commercial fishing efforts. In this paper, the frequency and distribution of dolphin foraging encounters in Mississippi Sound were examined from 2003 to 2009, revealing both short-and potentially long-term effects on dolphin foraging patterns following the hurricane. A pulse in dolphin foraging encounters was observed, which increased by ~15% in the 2 yr following the hurricane before returning to pre-Katrina levels. Statistically significant hot spots were identified through the use of the Getis-Ord Gi* hot spot analysis and revealed spatial shifts in foraging habitat consistent with prey selectivity. The results of this study support previous findings that coastal bottlenose dolphins in the southeastern United States are selective feeders, preferring to forage in deeper water known for soniferous prey species. Furthermore, this study presents important baseline information for future studies investigating other acute catastrophic events in Mississippi Sound, such as cumulative impacts following the Deepwater Horizon oil spill.

Scales and mechanisms of marine hotspot formation

“…A deeper mixed layer and higher phytoplankton density resulted in increased spawning habitat north of the Kuroshio. Smith et al (2013) examined how a hurricane passing through the Gulf of Mexico may have temporarily increased foraging hotspots for bottlenose dolphins. The decline in foraging habitat months after Hurricane Katrina suggests some hotspots, such as seagrass beds, may have been lost or disrupted by the hurricane.…”

Mapping spatial heterogeneity in the tumor microenvironment: a new era for digital pathology

“…These tools have been widely applied to robustly analyze spatial variability and capture patterns of environmental interaction, eg, the influence of hurricanes on dolphin foraging in marine ecology. 61 These powerful spatial descriptive statistics, commonly used in geographical data analysis, can be applied to pathological images that have been processed by digital pathology to extract spatial data such as cell locations. Studies employing the L-function 40 and the Kfunction statistic 36 to measure spatial homogeneity in cell location data have demonstrated initial success.…”

Collective behaviour is not robust to disturbance, yet parent and offspring colonies resemble each other in social spiders

“…An individual might retain its behaviour in spite of a disturbance, or it might find its behaviour changed as a result of a disturbance (Tuomainen and Candolin 2010; Sih et al 2011). The same could be true of group phenotypes; the collective behaviour of groups may resist disturbances, or it may be altered by them (Flack et al 2005, 2006; Smith et al 2013; Kubitza et al 2015; Formica et al 2016). For instance, collective behaviours might be “self-organised”, where individuals re-create the same group behaviour after disturbances by following the same set of interaction patterns that created the initial group behaviour (Bonabeau et al 1997; Fisher and Pruitt 2019; Fisher et al 2019).…”

“…In contrast, groups might change their behaviour following disturbances, if they are shunted into different “states” following a disturbance (Flack et al 2005, 2006; Doering et al 2018; Pruitt et al 2018), or engage in non-linear interactions that give divergent trajectories, and so different group phenotypes, from a similar set of starting conditions (May and Oster 1976; Cole 1994; Fisher et al 2018; Honegger and de Bivort 2018). However, the robustness of group phenotypes to disturbances is not well documented (Flack et al 2005, 2006; Smith et al 2013; Kubitza et al 2015; but see: Formica et al 2016).…”