Fecundity and Sexual Maturity of the Coral Siderastrea siderea at High Latitude Along the Florida Reef Tract, USA

Siderastrea siderea is one of the most abundant corals at high latitude shallow sites along the Florida Reef Tract (25°–27°N). This species is able to tolerate wide seawater temperature fluctuations and sedimentation stress, but its reproductive status at high latitudes and under marginal environmental conditions is poorly understood. The objectives of this study were to evaluate the reproductive potential of S. siderea along a latitudinal gradient (25°–27°N) and to determine if sexual maturity occurs in small (\u3c12.0 cm) S. siderea colonies. Samples of coral tissue were collected in 2007, 2008, and 2009 at three sites along the latitudinal gradient and were processed for histological analysis. Oocyte size, volume, and abundance were used to calculate fecundity. Results showed that fecundity decreased with increasing latitude and that oocyte volume was the major contributing factor to this variation. Mature oocytes were observed in S. siderea colonies at sizes as small as 1.1 cm in diameter. The ability of S. siderea to reach fertility at high latitude areas suggests this species is able to reproduce under marginal environmental conditions; however, reduction in oocyte size could increase local retention of larvae. The presence of mature oocytes in small colonies suggests that stress can reduce somatic growth and shift sexual maturity to smaller colony sizes

Black and White Photography: 3rd Place

https://nsuworks.nova.edu/occ_shuttershark_2009/1012/thumbnail.jp

Vertebrate Photography: Honorable Mention

https://nsuworks.nova.edu/occ_shuttershark_2010/1021/thumbnail.jp

Invertebrate Photography: 3rd Place

https://nsuworks.nova.edu/occ_shuttershark_2010/1008/thumbnail.jp

Reproductive Ecology of Siderastrea siderea: Histological Analysis of Gametogenesis, Spawning, and Latitudinal Fecundity Variation

The health of coral reefs has been decreasing globally due to acute and diffuse anthropogenic impacts. Historically corals have persisted through periods of adverse conditions for coral growth via evolutionary selective processes, making successful sexual reproduction paramount to the future of coral reefs. Little is known about sexual reproduction of Caribbean corals at high latitude, specifically in southeast Florida on the northern most extension of the Florida reef tract. Here, a comprehensive histological analysis of gametogenesis, spawning, and size of sexual maturity is provided for Siderastrea siderea at 26°N (Broward County, Florida, USA), with accompanying analysis of fecundity variation from the upper Florida Keys (25 N) through Martin County Florida (27°N). Histological analysis of tissue samples in combination with lunar, tidal, and temperature cues suggest primary spawning occurs following the new moon of October. Massive and rapid post-spawning oocyte resorption was observed and characterized across both years indicating that spawning is generally incomplete in the study area. Histological observations suggest that size at sexual maturity in a nearshore, high sediment environment may be \u3e20cm2 which is considerably smaller than previously reported. Fecundity decreased by 85% from 25°N to 27°N. Changes in fecundity were not attributed to significant differences in oocyte quantity between regions but to differences in oocyte volume which decreased by 65% from 25°N to 27°N. Drastic decreases in fecundity observed over a relatively small geospatial scale have important implications for regional population structure and connectivity and should prompt a further, multi-species, investigation

Black and White Photography: Honorable Mention

https://nsuworks.nova.edu/occ_shuttershark_2010/1005/thumbnail.jp

Land-Based Culture for the Restoration of Threatened Staghorn Coral

The staghorn coral Acropora cervicornis was recently listed as threatened under the Endangered Species Act due to a severe reduction over the last several decades throughout its range in Florida and the Caribbean. Natural recovery of this species is hindered by low sexual recruitment rates and limited local genetic diversity. Thus efficient options for restoration and conservation are needed. A widely accepted method of promoting natural recovery is to transplant genetically diverse colonies to reefs to promote sexual reproduction and resilience to disturbances and stressors. This project will test the feasibility of propagating corals through asexual fragmentation in land-based culture facilities for use in future restoration efforts. In addition, it will test the sexual compatibility of specific genotypes through fertilization and settlement success experiments. Finally it will examine changes in the microbial-coral association that may impact a coral\u27s susceptibility to disease and bleaching. Survival, health, and growth of coral fragments will be used as metrics to compare two land-based culture facilities and their performance in comparison to offshore nurseries. In addition, results of fertilization and settlement success of reciprocal crosses of four distinct genotypes will be useful to guide future decisions regarding transplantation of colonies for restoration. Propagating corals through both asexual and sexual methods will provide a two-pronged approach to increasing genetic diversity and promoting successful sexual reproduction necessary for species recovery