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The queen conch (Strombus gigas) is a large marine gastropod found throughout the tropical western Atlantic including Florida. Overfishing and habitat loss have led to Caribbean-wide population declines requiring regional protections. On Florida’s east coast, aggregations of conch were previously reported just south of a major shipping port near Ft. Lauderdale, unusually high latitude for the species. This study was designed to investigate the spatial extent and population demographics of the Ft. Lauderdale conch. In summer 2012, broad-scale population surveys were conducted to document benthic cover and conch distribution and size data along 72 random transects stratified across four habitats within 2 km north and south of the inlet. Younger conchs were found throughout the study area, but mostly in the colonized pavement west (CPW) habitat while old conchs were found exclusively at one CPW site south of the inlet. Significantly more conch were found on the CPW south habitat than any other. Benthic cover data suggests that CPW south may have a unique community composition dominated by macroalgae and sand. In summer 2013, the CPW south habitat was surveyed using cross-shelf transects measuring aggregation extent and demographics. Five hundred and twenty five conch were found, at a density of 495 conch per hectare. Confirmed mating sightings, females with eggs, and solitary egg masses were found indicating mating in this nearshore habitat is successful. Future research should include expanded broad-scale surveys to determine if other aggregations exist and monitoring to examine the effects of environmental change on this vulnerable species.

The queen conch, Lobatus gigas, is key to the Bahamian way of life. Recent studies suggest that commercial stocks will be depleted in The Bahamas in 10-15 years. In response to this, an egg farm was established in a historic breeding ground in Moriah Harbour Cay National Park, Exuma, Bahamas. Previously used for aquaculture, the egg farm concept was tested as a restoration method. Conch were tagged (n=251) and stocked in a 1,385 m2 (0.14 ha) circular enclosure at an equivalent density of 1,813/ha or 1 conch/5.5 m2. The egg farm was visited every 24-48 hours during the study period (May 26-August 14, 2019) to examine conch distribution, burial, predation, breeding, and egg mass laying. Queen conch Essential Fish Habitat was characterized in this study, contributing to a knowledge gap concerning conch spawning areas. No egg masses were laid, despite temperature, sediment solid-phase organics, calcium carbonate, and other seagrass habitat characteristics displaying similarities to previous studies in which conch spawned. It is speculated that egg laying did not occur due to handling disturbances, which may have caused the conch to resorb their gonads. Comprehensive recommendations are made for future egg farms intended for restoration. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

by Amber L. Garr. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web. / The presence of heavy metals and other pollutants is detrimental to marine ecosystems. The queen conch, once an important fisheries species in the Florida Keys, has not sufficiently recovered after a 25-year fishery closure. Research has shown high levels of copper and zinc in the gonads and digestive glands of adult conch found in the nearshore waters. Four sites relevant to queen conch larval recruitment were tested in 2010 for the presence of copper and zinc in the water, phytoplankton, sediment, and seagrass epiphytes over seven months. Both metals were detected in all sample types and no seasonal or geographical differences were detected. Surface water concentrations from the field were used to conduct acute and chronic toxicity tests on various ages of queen conch larvae and their phytoplankton food source. When zinc concentrations (0-40 (So(Bg/L) similar to those measured in situ were used, there was no significant impact on conch larval survival although some velar lobe de velopment was impaired. However, field concentrations of copper (0-15 (So(Bg/L), which often surpassed water quality standards, negatively impacted growth, survival, and development of the larvae. Chronic exposure to copper, through the water and food, disrupted the metamorphic success of competent larvae and decreased post-metamorphosis survival. Exposure to copper at later life stages increased mortality, suggesting that heavy metals have a negative effect on larval recruitment in localized areas of the Florida Keys. Structural equation modeling revealed that copper and zinc are moving through the systems differently and are best represented by two different models.