Variability in Beach Seine Samples at Small Spatial and Temporal Scales in a Near-Shore Estuarine Environment

Abstract

Abstract Fish communities at nine sites in three estuaries, all emptying into Charlottetown Harbour, PE, Canada, were sampled with beach seines to assess variability at small spatial (at the same sites, between sites within estuaries, between adjacent estuaries) and temporal (minutes, hours, days, months, ebb and flood tides) scales. A total of 11 species were identified, of which two (Fundulus heteroclitus [Mummichog] and Menidia menidia [Atlantic Silverside]) made up more than 90% of the individuals captured. Samples from the same sites taken 20–30 min apart did not differ with respect to number of individuals, number of species caught, or species diversity. However, the cumulative number of species continued to increase over the first five of six samples with repeated sampling at the same location. On larger spatial scales, communities (as measured by the Global R coefficients) differed more between sites within estuaries than between adjacent estuaries. Temporal variability in fish community compositi...