Seasonal patterns of habitat suitability and spatiotemporal overlap within an assemblage of estuarine predators and prey

Abstract

Subtropical estuaries often experience seasonal climatic shifts, which influence environmental conditions such as water temperature and salinity. The distribution of estuarine organisms depends on the availability of suitable environmental conditions, the extent of which may differ across seasons. Furthermore, ecological interactions among organisms, such as predation and competition, often occur when multiple species overlap spatiotemporally and can influence their distributions and abundances. Determining the habitat associations and overlap patterns among predator and prey species across seasons can thus enhance our understanding of ecosystem function. This study used a long-term monitoring data set to examine the habitat suitability and overlap patterns between 4 predator and 4 prey species in a northwestern Gulf of Mexico estuary. Seasonal (fall and spring) habitat suitability models and maps were created, which allowed for delineation of spatiotemporal overlap between predators and prey. Environmental drivers of habitat suitability differed among species, but temperature and salinity were frequently the most important variables. Seasonal differences in habitat suitability were observed for all species, but these differences were more notable for prey than for predators. Seasonality in habitat suitability was likely driven primarily by seasonal changes in environmental conditions and movements related to reproductive activities. Spatiotemporal overlap between predators and prey was observed primarily in whichever season each prey species was more abundant and in regions where highly suitable habitat was most ubiquitous for each predator. These results suggest that overlap between these predators and prey is highly seasonal, implying seasonality in the diets of predators and predation pressure on prey.

Grow fast, die young: Does compensatory growth reduce survival of juvenile blacktip sharks (Carcharhinus limbatus) in the western Gulf of Mexico?

“…While assessing the abundances and size structures of target species are among the primary aims for fisheries monitoring, the value of such programs reach beyond traditional stock assessments. Across the western GOM, long‐term monitoring by TPWD has provided insight into shark nursery function (Froeshcke et al, 2010 ), responses to environmental variability (Plumlee et al, 2018 ), and predator–prey relationships (Cottrant et al, 2021 ; Livernois et al, 2021 ). Our study illustrates the ecological mechanisms that shape variability in juvenile blacktip growth rates and residency patterns, and how monitoring parturition timing and water temperature can provide reliable predictions of early blacktip life history within the western GOM.…”

Ontogenetic changes in the tooth morphology of bull sharks (Carcharhinus leucas)

“…The bull shark Carcharhinus leucas Valenciennes, Müller & Henle 1839 is a versatile bite-feeding predator capable of inhabiting both freshwater and marine environments in tropical and temperate regions worldwide and exploiting diverse resources (Espinoza et al, 2021;French et al, 2017;Heupel et al, 2015;Lee et al, 2019;Livernois et al, 2021;Niella et al, 2017Smoothey et al, 2016Smoothey et al, , 2019Thorburn & Rowland, 2008;Werry et al, 2011). Juvenile C. leucas use estuaries as nursery areas Matich & Heithaus, 2015) and while adults are considered apex predators, juveniles are not.…”