This introductory text on the design and analysis of sample surveys emphasizes the practical aspects of survey problems. It begins with brief chapters on the role of sample surveys in the modern world. Thereafter, each chapter introduces a sample survey design or estimation procedure by describing the pertinent practical problem. The authors describe the methodology proposed for solving the problem and provide the details of the estimation procedure, including a compact presentation of the formulas needed to complete the analysis. Then, a practical example is worked out in complete detail. At the end of each chapter, a wealth of exercises gives students ample opportunity to practice the techniques and stretch their grasp of ideas.

Elementary Survey Sampling

The importance of restoring filter-feeders, such as the Eastern oyster Crassostrea virginica, to mitigate the effects of eutrophication (e.g. in Chesapeake Bay) is currently under debate. The argument that bivalve molluscs alone cannot control phytoplankton blooms and reduce hypoxia oversimplifies a more complex issue, namely that ecosystem engineering species make manifold contributions to ecosystem services. Although further discussion and research leading to a more complete understanding is required, oysters and other molluscs (e.g. mussels) in estuarine eco- systems provide services far beyond the mere top-down control of phytoplankton blooms, such as (1) seston filtration, (2) benthic-pelagic coupling, (3) creation of refugia from predation, (4) creation of feeding habitat for juveniles and adults of mobile species, and for sessile stages of species that attach to molluscan shells, and (5) provision of nesting habitat.

/pdf/ecosystem-services-related-to-oyster-restoration-2s5ki3syld.pdf

Ecosystem services related to oyster restoration

https://pubag.nal.usda.gov/download/29264/PDF

The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

Coastal protection remains a global priority. Protection and maintenance of shoreline integrity is often a goal of many coastal protection programs. Typically, shorelines are protected by armoring them with hard, non-native, and nonsustainable materials such as limestone. This study investigated the potential shoreline protection role of created, three-dimensional Eastern oyster (Crassostrea virginica) shell reefs fringing eroding marsh shorelines in Louisiana. Experimental reefs (25 × 1.0 × 0.7 m; intertidal) were created in June 2002 at both high and low wave energy shorelines. Six 25-m study sites (three cultched and three control noncultched) were established at each shoreline in June 2002, for a total of 12 sites. Shoreline retreat was reduced in cultched low-energy shorelines as compared to the control low-energy shorelines (analysis of variance; p < 0.001) but was not significantly different between cultched and noncultched sites in high-energy environments. Spat set increased from 0.5 ± 0.1 spat/shell in July 2002 to a peak of 9.5 ± 0.4 spat/shell in October 2002. On average, oyster spat grew at a rate of 0.05 mm/day through the duration of the study. Recruitment and growth rates of oyster spat suggested potential reef sustainability over time. Small fringing reefs may be a useful tool in protecting shorelines in low-energy environments. However, their usefulness may be limited in high-energy environments.

The Potential for Created Oyster Shell Reefs as a Sustainable Shoreline Protection Strategy in Louisiana

/pdf/asian-carps-of-the-genus-hypophthalmichthys-pisces-35eauajd0q.pdf

Asian Carps of the Genus Hypophthalmichthys (Pisces, Cyprinidae) ― A Biological Synopsis and Environmental Risk Assessment

Decapod crustaceans occupying seagrass, salt marsh edge, and oyster habitats within the St. Martins Aquatic Preserve along the central Gulf coast of Florida were quantitatively sampled using a 1-m2 throw trap during July–August 1999 and March–April 2000. Relative abundance and biomass were used as the primary measures to compare patterns of occupancy among the three habitat types. Representative assemblages of abundant and common species from each habitat were compared using Schoener's Percent Similarity Index (PSI). In all, 17,985 decapods were sampled, representing 14 families and 28 species. In the summer sampling period, mean decapod density did not differ between oyster and seagrass habitats, which both held greater densities of decapods than marsh-edge. In the spring sampling period oyster reef habitat supported greater mean decapod density than both seagrass and marsh-edge, which had similar densities of decapods. Habitat-specific comparisons of decapod density between the two sampling periods indicated no clear seasonal effect. In summer 1999, when seagrasses were well established, decapod biomass among the three habitats was not significantly different. During spring 2000, decapod biomass in oyster (41.40 gm−2) was greater than in marshedge (4.20 gm−2), but did not differ from that of seagrass (9.73 g m−2). There was no significant difference in decapod biomas between seagrass and marsh-edge habitats during the spring 2000 sampling period. The assemblage analysis using Schoener's PSI indicated that decapod assemblages associated with oyster were distinct from seagrass and marshedge habitats (which were similar). The results of this study suggest that in comparison to seagrass and marsh-edge habitats, oyster reef habitats and the distinct assemblage of decapod crustaceans that they support represent an ecologically important component of this estuarine system.

Comparative patterns of occupancy by decapod crustaceans in seagrass, oyster, and marsh-edge habitats in a Northeast Gulf of Mexico estuary

Evaluation of aquaculture effluents

Bighead carp, Aristichthys nobilis Rich., dry weight food assimilation rates ranged from 37 to 49% (average 43%). The filtration rate ranged from 185 to 256 ml h−1 g−1 and was higher in larger fish. Bighead carp filtered Chlorella vulgaris (6 ± 0.4 µ diam) inefficiently (0.1 %), but the efficiency increased to 13 % for the larger Scenedesmus sp. (12 ± 1.7 µ diam). Fish kept in cages were forced to filter-feed, whereas fish kept free in the same pond were opportunistic plankton and bottom feeders. Free fish grew faster.

Food assimilation and filtering rate of bighead carp kept in cages

Large swarms of non-biting midges (Diptera: Chironomidae) emanating from some central Florida lakes can cause severe nuisance and economic problems for businesses, residents, and visitors within the dispersal range of these insects (Ali 1995). Midges are also a cause of allergies to humans (Cranston 1995). Because of these problems, a systematic research program on the bionomics and management possibilities of midge populations in central Florida has continued for the past two decades (Ali 1996). As a part of this program, a preliminary investigation of fish predation on chironomid midge larvae for the biological control perspective of midges was conducted. Midge predatory fish (bluegill,Lepomis macrochirus) were collected from two lakes on four occasions to elucidate any relationships between consumption of midge larvae by these fish and the associated larval composition and distributions in the lakes. Information concerning fish predation on midge larvae, species or habitat specific, would be useful in devising new control strategies. Fish were collected (May 1999, July, September and December 2000) from Lakes Dora and Yale (Lake County, Florida) by electrofishing under permit from Florida Fish and Wildlife Conservation Commission. Collections were made between 0830 and 1200 h and up to twenty fish were collected from near-shore areas. Fish were identified and killed immediately, maintained on ice while transported to the laboratory, and stored at -10?C until examined. For examination, each fish was thawed and the foregut was dissected (Bowen 1996), and the contents transferred to 4-dram vials containing 70% ethanol. Gut contents were examined under variable magnification of a dissecting microscope and enumerated. Chironomidae head capsules and associated fragments were wet mounted on slides and examined at 400x magnification using a phase-contrast microscope and identified to lowest possible taxonomic level using the keys of Epler (1995). Only head capsules with sufficient morphological features remaining for identification were counted for gut content enumeration, other fragments were used to improve identification where possible. Five to 20 fish were successfully collected per sampling occasion (Table 1). Midge larvae of the tribe Tanytarsini (>90% Cladotanytarsus spp.) were most numerous in gut contents of fish from both lakes (Table 1), comprising 55.9-62.8% of total consumed midge larvae from Lake Dora and 4.8-48.1% from Lake Yale. Geoldichironomus spp. larvae were the next most common in the gut contents of fish from Lake Dora (0.0-27.5% of total larval chironomids). Other midge larvae consumed by fish from Lake Dora included Chironomus crassicaudatus, Glyptotend ipes paripes, Cryptochironomus spp., Pseudochironomus spp. and Tanypodinae. Seasonal mean number of total midge larvae in fish gut contents ranged from 4.7 to 44.0. Midge larvae were present in the gut contents of all fish from Lake Dora, except those collected in December 2000, when 40% of collected fish had empty guts. This was likely due to low water temperatures reducing feeding activity, as suggested for bluegill during winter months by Gilinsky (1984). Pseudochironomus spp. larvae were the second most prevalent midge larvae in the fish gut contents of Lake Yale, forming up to 46.2% of total midge larvae, followed by C. crassicaudatus (collected only during May 1999), G. paripes, Cryptochironomus spp., and Tanypodinae. Seasonal mean number of larvae per fish in Lake Yale ranged between 1.0 and 18.9. Bluegill feeding on midge larvae in Lake Yale was also reduced during December 2000, though only one fish had an empty gut. Other food items identified from fish in these two lakes included immature Insecta (Odonata, Ephemeroptera and Trichoptera), Crustacea (Decapoda, Amphipoda and Ostracoda), Nematoda, Oligochaeta, Gastropoda, and some unidentifiable material. These food items numerically were only a small part of total gut contents in most fish examined (data not shown). To estimate relative selective feeding by bluegill on examined chironomid larvae, percent composition of chironomid larvae in gut contents of collected fish was compared to overall percent composition of chironomid larvae in study lakes and percent composition of midge larvae in the nearshore areas with firm sediments representative of the areas from where the fish were caught, collected concurrently and reported by Lobinske (2001) (Fig. 1). In Lake Dora, Tanytarsini were most common, exhibiting similar percent compositions in fish gut contents in the entire lake as well as in nearshore areas. During July, Septem-

Predation by bluegill (lepomis macrochirus) on larval chironomidae (diptera) in relation to midge standing crop in two central florida lakes

A mail survey was conducted in 1991 to identify barriers-to-entry into the Florida aquaculture industry. The survey was administered to all 586 individuals on the Florida Agricultural Statistics Service aquaculture industry participant mailing list. Two hundred twenty of the 227 returned questionnaires were complete. Of these, 175 respondents currently owned an aquaculture business; 141 reported producing only one species (defined in this study to be the general collection of species such as ornamental fish or aquatic plants rather than specific species within these groups), 29 reported producing two different species, and four reported producing three or more species. In order to analyze the data by species; only those aquaculturists producing single species were included in the final analyses. The survey results showed that economic factors (financial and marketing) presented the greatest barriers-to=entry into the Florida aquaculture industry, while regulatory barriers were relatively less problematic....

Economic, regulatory, and technological barriers to entry into the Florida aquaculture industry

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