Editorial Type:
Article Category: Research Article
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Online Publication Date: Dec 01, 2000

Dynamics of the Offshore Fish Assemblage in a Southwestern Reservoir (Lake Texoma, Oklahoma–Texas)

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Page Range: 917 – 930
DOI: 10.1643/0045-8511(2000)000[0917:DOTOFA]2.0.CO;2
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Abstract

Reservoirs are relatively new ecosystems with fish assemblages that include both native and introduced species. Spatial and temporal variability in such fish assemblages is difficult to predict from ecological theory. We characterized the dynamics of an offshore fish assemblage of Lake Texoma by sampling multiple fixed sites fortnightly with gill nets from 1981 to 1984 (402 net-nights). Univariate and multivariate analyses were used to quantify (1) variation of the fish assemblage in space and time, (2) spatial and temporal independence of samples, (3) persistence of species associations, and (4) correlations between the dynamics of the fish assemblage and environmental conditions. Overall, depth and season accounted for the greatest amount of variation in the fish assemblage in our study area. Much of this variation was the result of spatial and temporal fluctuation in the abundance of various age classes of Dorosoma cepedianum (Gizzard Shad), Morone saxatilis (Striped Bass), and Aplodinotus grunniens (Freshwater Drum). With the exception of a winter kill of the nonnative Dorosoma petenense (Threadfin Shad), the reservoir fish assemblage differed little among years. Species associations were constant across years during the warm season but not in cold seasons. Overall, the fish assemblage in our study area remained relatively consistent, in spite of considerable variability in reservoir volume, turbidity, and temperature.

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Copyright: The American Society of Ichthyologists and Herpetologists
Fig. 1.
Fig. 1.

Reservoir volume, Secchi depth, inflow from the Red River and surface water temperature from Lake Texoma for each sample date

Fig. 2.
Fig. 2.

Abundance of 18 common species and age classes caught in gill nets in Lake Texoma across the 67 sample dates. Number of individuals was pooled across sample sites for each given date. Note, scale of the y-axis varies among species

Fig. 3.
Fig. 3.

Correspondence Analysis of the gill net samples from Lake Texoma. Top graph, sample scores; bottom graph, species scores. Species codes represent the first three letters from the genus and specific epithet. Suffixes -s, -m, and -l represent small, medium, and large size classes, respectively

Fig. 4.
Fig. 4.

Plots of the first two axes of the correspondence analysis in Figure 3, separated by year and season (left column; c = cold, w = warm), and habitat and depth (right column; b = bottom, s = surface)

Fig. 5.
Fig. 5.

Semivariograms representing the divergence (semivariance) of the fish assemblage in Lake Texoma at different sample intervals apart, based on the three community indices [species richness, number of individuals, and correspondence analysis (CA) axis scores]

Fig. 6.
Fig. 6.

Dendrograms from UPGMA clustering of species associations across the six gill net sites on Lake Texoma. Each dendrogram represents the associations for a given year and season. Species codes are as in Figure 3

Fig. 7.
Fig. 7.

Canonical correspondence analysis used to describe correlation of environmental factors with the variation in the fish assemblage of Lake Texoma. Each point is derived from pooled species abundances across sites for a given sample date. Top graph, sample and species scores with season in which samples were taken delineated by open (cold) and closed (warm) circles. Bottom graph, vector arrows representing the correlation of environmental factors with variation in fish assemblage. Species codes as in Figure 3

Fig. 8.
Fig. 8.

General distribution patterns of fishes across the six gill net sites on the Red River arm of Lake Texoma for summer and winter months. Letter font represents the relative abundance of that species at a site for the given season

Accepted: Apr 10, 2000