David A. Blewett

Short-term Effects of a Low Dissolved Oxygen Event on Estuarine Fish Assemblages Following the Passage of Hurricane Charley

Hurricane Charley, a category 4 storm, passed directly over the Charlotte Harbor estuary and Peace River watershed on August 13, 2004. Following the storms passage, dissolved oxygen in the Peace River fell below 1 mg l−1 and hypoxic conditions (<2mgl−1) extended into Charlotte Harbor. A long-term fisheries-independent monitoring program (1989 to present) was already in place in Charlotte Harbor, and sampling was intensified during the month after the storm. Changes in fish assemblages that resulted from the hypoxic event were determined using nonmetric multidimensional scaling and similarity percentages analysis. At the mouth of the Peace River and upper Charlotte Harbor, fish abundance decreased dramatically after the hurricane, and typical estuarine fish assemblages were replaced by those dominated by a few resilient estuarine and freshwater species, including the nonindigenous brown hoplo (Hoplosternum littorale) and sailfin catfish (Pterygoplichthys spp.). Fish assemblages in the estuarine portion of the Maykka River, located only a few kilometers west of the Peace River, were unaffected. The hypoxic event was short lived; dissolved oxygen and estuarine fish assemblages in the Peace River and upper Charlotte Harbor recovered within a month. The results of this study are consistent with other hurricane-related hypoxic events in the literature which have reported acute effects to estuarine systems in the short term, rapid recoveries, and long-term resilience.

Relative Abundance and Distribution of Common Snook along Shoreline Habitats of Florida Estuaries

Abstract Quantitative estimates of relative abundance, spatial and temporal distribution, and habitat preference of common snook Centropomus undecimalis along shoreline habitats in four Florida estuarine areas were determined. Significant differences in the relative abundance of common snook among the estuarine areas suggested marked variation in common snook population abundance and densities on a regional scale. The highest adjusted mean relative abundance of common snook occurred in the southern Indian River Lagoon (4.68 fish/haul; SE = 0.08), followed by Tampa Bay (3.36 fish/haul; SE = 0.11), Charlotte Harbor (2.13 fish/haul; SE = 0.10), and the northern Indian River Lagoon (0.76 fish/haul; SE = 0.21). Several common factors (e.g., mangrove and seagrass habitat, salinity, and water temperature) among the estuarine areas were linked with common snook relative abundance and distributions, allowing us to better understand how these fish interact with their environment in different regions of Florida.

Fish Assemblages in the Oligohaline Stretch of a Southwest Florida River during Periods of Extreme Freshwater Inflow Variation

Abstract Maintenance or restoration of the oligohaline stretch (i.e., salinity 0.5–5 psu) of coastal rivers is becoming an increasingly important goal of water managers striving to balance human consumption of water with the ecological integrity of estuaries. The objectives of this study were to compare fish assemblage structure and species abundance of the oligohaline stretch to those of the lower river mouth during periods of varying freshwater inflow (wet and dry periods) in one of southwest Floridas largest rivers, the Peace River. The abundance of several estuarine residents and estuarine transients captured in 21.3-m seines—Sand Seatrout Cynoscion arenarius, Tidewater Mojarra Eucinostomus harengulus, Red Drum Sciaenops ocellatus, and Spot Leiostomus xanthurus—were similar between river sections, which is consistent with the premise that the oligohaline stretch is an extension of the juvenile habitat known to be important for fish in lower rivers. Estuarine residents known to have affinities for mar...