Persistence and Structure of the Fish Assemblage in a Small California Stream

Abstract

The persistence and structure of a small but morphologically diverse fish assemblage of a California stream was examined to see if it had the characteristics of a deterministically regulated or stochastically regulated community. We evaluated persistence by monitoring the fish populations for 5 yr and examined resource use by measuring summer microhabitats and diets of each species. We also compared the microhabitats and diets of the juveniles and adults of each species to investigate the hypothesis that in stream fish assemblages at low diversity, juvenile fishes essentially function ecologically as separate species. Species composition in each of four stream sections was persistent over the 5—yr period, which included extreme flood conditions. Differences in species composition among sections reflected differences in their physical characteristics. The most abundant species were segregated by habitat, microhabitat, and/or diet. In addition, in all but one species, young—of—year were ecologically segregated from the adults; this increased the functional complexity of the assemblage. The observed fish assemblage thus appears to have the characteristics of a highly structured community, as expected under Connell's “niche diversification hypothesis.” The structure observed is probably characteristic of fish assemblages in cold—water streams throughout North America that contain the same or similar species.

Effect of daily variation on the seasonality of testate amoebae community structure in different environments of a Neotropical floodplain

“…Other studies have reported high variability in macroinvertebrate and fish communities under relatively constant environmental conditions (Moyle and Vondracek, 1985;Townsend et al, 1987;Weatherley and Ormerod, 1990;Scarsbrook, 2002;Milner et al, 2006). Our results suggest that variability in environmental factors was not detected due to characteristics of the water body.…”

Simulation de l'habitat physique du barbeau fluviatile (Barbus barbus, L. 1758) : choix des modèles biologiques et sensibilité de la réponse

“…C'est un niveau d'étude pertinent pour décrire la sélection de l'habitat par les poissons (GORMAN et KARR, 1978 ;SCHLOSSER, 1982 ;MOYLE et VONDRACEK, 1985). Plusieurs modèles biologiques d'utilisation et de préférence vis-à-vis de l'habitat ont été proposés en respectant cette logique.…”

Factors influencing the structure and spatial distribution of fishes in the headwater streams of the Jaú River in the Brazilian Amazon

“…Caramaschi (1986) found that fish distribution in the small streams of the Tietê Basin were linked to physical characteristics of the channel and the heterogeneity of benthic substrates. The diversity and abundance of stream fish communities has also been associated with physical characteristics of the fluvial environment (Gorman and Karr, 1978;Moyle and Vondracek, 1985;Magalhães et al, 2002;Pouilly et al, 2006;Romanuk et al, 2006). In a study of a fish community of the Owego Creek, in New York, Sheldon (1968) concluded that variation in channel depth of stream habitats controlled the longitudinal distribution and diversity of fish assemblages.…”