Capstone Title

Marine Fish Assemblage on the Deep Artificial Reefs of Broward County, Florida, USA

Defense Date

9-2003

Document Type

Capstone

Degree Name

M.S. Marine Biology

First Advisor

Richard Spieler

Second Advisor

Emily Schmitt

Abstract

Nova Southeastern University (NSU) Oceanographic Center (OC) accepts completion of either a capstone, a comprehensive literature review of a subject, or a conventional thesis to meet the requirements for a Masters in Science degree. This capstone paper is a hybrid of the two; incorporating a review of existing literature on deep artificial reef fish assemblages, as well as databases, interviews with other individuals engaged in similar studies, and new data collected independently of the NSUOC. The new data was collected using advanced SCUBA diving techniques, involving breathing mixtures of oxygen, helium, and nitrogen (trimix). The dives were conducted from charter boats on artificial reefs (vessel-reefs) deployed by the Broward County Department of Planning and Environmental Protection (DPEP) at depths from 40 to 80 meters (m). During each dive, a 15-minute survey was performed using a modified roving diver technique (RDT) and the species, abundance and size class of all fish observed within 3 m of the vessel reef superstructure were recorded. Species abundance, diversity, and total biomass from each site were calculated. Data collected for this study were compared to data previously collected on the shallower artificial reefs of Broward County, Florida.

Little is known about the assemblage of marine fishes below 40 m worldwide; 94% of the species I recorded during the dives were found at depths exceeding at least one of the references used. An analysis of the correlation between maximum depth, vessel length, years submerged, and minimum temperature; as well as the number of individuals, number of species, species diversity, total biomass, and average biomass of the fishes on each site suggest a relationship may exist between them. The results suggest that maximum depth has a stronger influence on the number of individuals, number of species, species diversity, total biomass, and average biomass than the other variables, and that they each decrease as depth increases. However, due in part to the small sample size (n=9), these observations are not statistically significant. Comparison of the data collected in this study to the findings of previous studies performed on artificial reefs off Broward County revealed differences in the fish assemblages. Two fish species, Chaetodon aya and Holanthias martinicensis, that have not been recorded on the shallow Broward County natural or artificial reefs were observed on more than one deep vessel reef; and two deepwater species, Lutjanus buccanella and Epinephelus niveatus, that were previously recorded on shallow Broward County vessel-reefs were not observed on any of the deep vessel-reefs. The assemblage of fish observed was not anticipated based on available literature regarding the depth ranges of marine fishes. Although the presence of large game fishes was anticipated on the deeper vessel-reefs because they are outside sport diving limits, very few were observed.

Additional studies should be completed to fully document the assemblage of marine fishes below 40 meters, as well as improve the literature regarding the maximum depth range of each species.

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