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Habitat and trophic niche overlap among juvenile black sea bass, tautog, and cunner: interspecific interactions amid a species geographic range expansion
Citation:
Taylor, D., C. Pearson, L. Green-Gavrielidis, N. Hobbs, C. Thornber, G. Cicchetti, A. Gerber-Williams, AND M. McManus. Habitat and trophic niche overlap among juvenile black sea bass, tautog, and cunner: interspecific interactions amid a species geographic range expansion. MARINE ECOLOGY PROGRESS SERIES. Inter-Research, Luhe, Germany, 720:133-159, (2023). https://doi.org/10.3354/meps14409
Impact/Purpose:
This work explores changes to two economically and recreationally important fish species in Narragansett Bay in different habitats as warm water southern species move north into the bay. We looked at the rapidly increasing populations of juvenile black sea bass (a southern species) and the existing populations of juvenile tautog and cunner as competitors for food and habitat. This serves as a baseline for evaluating the changing effects of black sea bass as populations and predatory effects of this species presumably increase in the future.
Description:
Juvenile black sea bass Centropristis striata populations are increasing in southern New England estuaries of the northeastern USA with possible trophodynamic effects on labrid species: tautog Tautoga onitis and cunner Tautogolabrus adspersus. In this study, we examined the abundance, size-structure, and feeding ecology of juvenile sea bass and labrids in Narra- gansett Bay (Rhode Island, USA) from June to October in 2018 and 2019 and evaluated potential interspecific competition using habitat, diet, and isotopic niche overlap indices. Juveniles (age-0+) of each fish species spatiotemporally co-occurred in shallow, polyhaline habitats throughout the estuary. Age-0 cohorts were numerically dominant across species and initially recruited to the study area in July (minimum total length, TL = 15−20 mm), reached peak abundances in mid- to late summer (maximum abundances = 12−140 fish 100 m−2), and emigrated from field sites in October (maximum TL = 85−96 mm). Stomach content and stable isotope (d15N and d13C) analyses determined that focal fishes were generalist carnivores that foraged in bentho−pelagic food webs. Fishes also overlapped in their respective ambit and core isotopic niche space, but interspecific dietary overlap was size-dependent. Dietary overlap was most pronounced between sea bass ≤ 49 mm TL and labrids ≤ 59 mm TL due to their mutual reliance on gammarid and caprellid amphipods. Ontogenetic dietary shifts then resulted in food niche segregation, such that sea bass 50−139 mm TL consumed decapod crustaceans and fish, whereas labrids 60−181 mm TL mainly fed on amphipods, worms, bivalves, and turf-associated biota, i.e. bryozoans, hydroids, and sea- weeds. Habitat and trophic niche overlap between early juvenile sea bass and labrids purportedly have not caused opposite population trajectories or food resource limitation in Narragansett Bay, indicating an absence of exploitative competition. Alternatively, realized competition between species may be too spatiotemporally restricted to alter their population dynamics. Continuous monitoring of the sea bass’s bio-ecological effects in southern New England estuaries is war- ranted, however, given their recent range expansion and increasing abundances at northern latitudes.
URLs/Downloads:
DOI: Habitat and trophic niche overlap among juvenile black sea bass, tautog, and cunner: interspecific interactions amid a species geographic range expansion