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Feeding Ecology of the Tidewater Goby
Author(s) -
Swenson Ramona O.,
McCray Aria T.
Publication year - 1996
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1996)125<0956:feottg>2.3.co;2
Subject(s) - tidewater , biology , goby , predation , ecology , invertebrate , estuary , habitat , marsh , nursery habitat , wader , planktivore , fishery , wetland , nutrient , phytoplankton , fish <actinopterygii> , paleontology , glacier
We investigated the feeding ecology of the tidewater goby Eucyclogobius newberryi , a California estuarine fish that is federally listed as an endangered species. We compared the diet during three seasons (April, August, and November 1992) in three habitats (lagoon, creek, and marsh). Tidewater gobies ( N = 331; standard lengths [SL], 15–46 mm) fed on benthic invertebrates, principally ostracods, chironomid larvae, and the gammarid amphipod Corophium spinicorne . Other prey taxa included polychaetes, oligochaetes, isopods, the gammarid amphipod Eogammarus ramellus , copepods, mysids, and invertebrate eggs. Diet variability within samples was low, but diet varied across seasons and sometimes habitats. The tidewater goby appeared to be a specialist that can forage opportunistically in some circumstances. Comparisons between the diet and available resources in August indicated selectivity in the lagoon and marsh (albeit for different prey), but general feeding in the creek. Laboratory observations of feeding behavior revealed preferences for C. spinicorne and chironomid larvae (without the mucus tube) and suggested that substrate differences among the habitats could influence the diet by altering the mode of feeding (sifting sand in mouth versus plucking prey from gravel). Comparison of the diets ofjuveniles (<27 mm SL) and adults did not reveal an ontogenetic shift in diet. Analysis of the daily feeding pattern in November showed that juveniles fed at all hours whereas adults fed principally at night. The tidewater gobyˈs feeding ecology suggests that it is adaptable to a variety of habitats. Fish from the marsh were substantially larger than those from other habitats, suggesting that marshes provide better opportunities for growth. The tidewater gobyˈs diet overlaps with those of other California gobies, including two introduced species that are potential competitors and predators.