Title

Ecology of the ichthyofauna of La Restinga Lagoon, Margarita Island, Venezuela

Date of Award

1987

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Marine Biology and Fisheries

First Committee Member

C. Richard Robins, Committee Chair

Abstract

The ecology of the fishes of La Restinga were investigated. Field data were collected in 1972-1973 and 1983-1986. Over 20,500 fishes were collected in 1972-1973, comprising 32 families, 53 genera and 67 species. Thirty-seven species were represented by fewer than 30 individuals. Catches were dominated by a small fraction of all species collected. The atherinid Xenomelaniris brasiliensis comprised 17 percent; three anchovy species represented over 30 percent, and one sardine species comprised 10 percent of the catch. Five families (Engraulidae, Atherinidae, Clupeidae, Sparidae and Gerreidae) represented over 75 percent of the catch. Thirty-six species were classified as permanent residents; 11 species appeared to be cyclical, and 20 species occasional visitors. Thirty-one species were classified as first order, 24 as second order and 12 as third order consumers. Twenty-nine species were represented in the catches by 30 or more individuals. Several species have protracted spawning seasons, with peak spawning activity synchronized with seasonal upwelling off northeastern Venezuela. The most abundant species were small-size planktivores and various small to large omnivorous species. Number of species collected at various stations were not significantly correlated with temperature, salinity or dissolved oxygen. Spatial and temporal patterns of food abundance may be more important than abiotic factors in determining distribution and abundance of coastal lagoon fishes. Based on the 1972-1983 and 1983-1986 collections, patterns of species composition and abundance of fishes in La Restinga are persistent over time. Number of species collected depends on the number of samplings, gear and time at which sampling takes place. More species and larger individuals were collected over a diel cycle than were collected at the same stations by previous studies sampling once a day. Cluster analysis based on species occurrence separated stations sampled into four groups, indicating gear selectivity. Considerable environmental variability and taxonomic diversity of fishes exists in 35 coastal lagoons in the western central Atlantic. Most studies of fish communities in these lagoons had inadequate sampling schedules and gear bias, and did not account for biological rhythms. Because of microhabitat diveristy, various gear should be used over 24 hr cycles to sample coastal lagoon fishes and characterize diel and seasonal variability in population parameters. (Abstract shortened with permission of author.)

Keywords

Biology, Oceanography

Link to Full Text

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