Ichthyoplankton Of The Flower Garden Banks, Northwest Gulf Of Mexico (reef, Multivariate Analysis, Fish, Oil Pollution, Recruitment)

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Marine Biology and Fisheries


Ichthyoplankton were collected at the East and West Flower Garden reefs, nearby drilling platforms, and control areas with standard and opening-closing bongo nets on eight cruises October 1980-October 1982 to characterize the larval fishes of the area and to assess impact of the platforms. Gobiidae, Bregmacerotidae, Bothidae, Synodontidae, and Myctophidae accounted for 67% of 39,674 larvae in 85 families in 217 samples. Density (n/1000 m3) and diversity (n families) were generally greater in autumn coinciding with a stable, warm, 50-60m deep surface mixed layer (SML), and were greater in the SML than below it or in the bottom nepheloid layer (BNL). Gonostomatidae, Myctophidae, and Bregmacerotidae were more abundant early in the year and these plus the Ophidiidae were more abundant below the SML layer. Gonostomatids were most abundant in the BNL. Small larvae of Apogonidae, Acanthuridae, Labridae, Scaridae, Lutjanidae, Serranidae, and Pomacentridae confirm that reef fishes spawn at or near the Flower Gardens. Differences in family rank order and abundance between the East Flower Garden reef and the nearby platform and control stations were depth-related and reef vs. platform + control in kind, based on cluster analyses. No effects of installation and operation of the drilling platform were found during this study. R-mode principal component and factor analyses found several independent patterns of variation among families and generally low communalities suggesting little competition at the family level. The Flower Garden ichthyoplankton are an ecotone assemblage of the larvae of outer continental shelf, mesopelagic, pelagic, live-bottom, and coral reef fishes. Samples from this assemblage and four others in the Gulf and Caribbean were correctly classified to area 80% of the time by discriminant analysis (DA) using the 19 most abundant families present in all areas. The five assemblages are separated on four axes: ocean-coast, seasonality, evenness-diversity, and herring suitability. The DA ordination is a visual multivariate baseline to monitor changes in ichthyoplankton composition. Larvae of Ranzania, Echiodon, and Pontinus were found for the first time in the western Gulf of Mexico.


Biology, Oceanography

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