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Evaluating different methods to determine a cause for reproductive failure in Lobatus gigas.
Title
Evaluating different methods to determine a cause for reproductive failure in Lobatus gigas.
Name/Creator
Pollard, Madison Jane
Abstract/Description
Queen conch (Lobatus gigas) have been experiencing low reproduction rates throughout their distribution. Imposex female conchs have been observed with male verges in the British Virgin Islands and have been linked to areas of high boating activity. While in the Florida Keys, reduced reproduction has been linked to Lobatus gigas located in nearshore habitats. This literature review will evaluate the most effective method to determine a cause for reproductive failure in Lobatus gigas. In the...
Show moreQueen conch (Lobatus gigas) have been experiencing low reproduction rates throughout their distribution. Imposex female conchs have been observed with male verges in the British Virgin Islands and have been linked to areas of high boating activity. While in the Florida Keys, reduced reproduction has been linked to Lobatus gigas located in nearshore habitats. This literature review will evaluate the most effective method to determine a cause for reproductive failure in Lobatus gigas. In the British Virgin Islands, Cassander Titley-O’Neal analyzed imposex females and performed a butylin analysis on the digestive glands and food resources within the habitat the conch were collected. Titley-O’Neal recognized imposex morphology in Lobatus gigas and collected samples based on these features in areas of high boating activity, using reproductively normal conch from areas of low boating activity as reference. Gabriel Delgado compared the gonadal tissue and cerebral ganglia cell diameter and density of non-imposex queen conch offshore and nearshore in the Florida Keys. In the La Parguera area of Puerto Rico, Shawna E. Reed compared the gonads of imposex females to normal female conch gonads. Low concentrations of Tributyltin (TBT) in the turtle grass and marine algae samples taken by Titley-O’Neal, suggested food source is not enough uptake of TBT to cause imposex in Lobatus gigas. The presence of TBT was found in both male and female digestive glands, and in all sites, except one reference site, Anegada, but was highest in boating active sites. Concentration of Tributyltin was observed to be higher in male conch compared to females of the same area. The nearshore male and female queen conch of the Florida Keys were found to have less than 50% developed gametogenic tissue resulting in more than half being sexually inactive. The offshore population were observed to be highly reproductive with over 50% developed oogenic tissue in females and over 75% spermatogenic tissue in males. Delgado concluded that there appears to be abnormalities in the cerebral ganglion (c.g. responsible for hormone production) and deficiencies in the gonads of nearshore conch, both associated with reproduction. Given there was no environmental samples taken, there is no confirmed environmental or physical source for the cause of the abnormality in nearshore conch, other than the closer geographic proximity to anthropogenic factors. Reed compared imposex gonads to the gonads of normal reproducing females and determined no difference in sexual tissue. Imposex females demonstrated no male-like behavior. One imposex female was collected near an egg mass and had emptied signet cells, indicating successful reproduction. After evaluating each method, it appears abnormalities in cerebral ganglia, and deficiencies in gonads have been more successful in providing reason for reproductive failure in Lobatus gigas, compared to looking at masculinized females. Imposex has not yet been proven to have a negative effect on conch reproduction other than hypothesized issues regarding eggs masses as of present. Further study in the spawning of normal and imposex queen conch, with specific attention to their egg masses and habits, can potentially link imposex to failing reproduction among aggregations. Butlytin analysis on the gonads of queen conch may determine a link between Tributyltin concentration and delay in gametogenic tissues. Further research in water quality and sediment sampling to detect TBT in habitats of Lobatus gigas spawning.
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Date Issued
2020-06-15
Identifier
BC745
Format
Document (PDF)
PURL
http://purl.flvc.org/broward/fd/BC745
How will the predicted ocean temperatures of 2100, impact larval development of Lobatus (Strombus) gigas in the Caribbean region?
Title
How will the predicted ocean temperatures of 2100, impact larval development of Lobatus (Strombus) gigas in the Caribbean region?.
Name/Creator
Pollard, Madison Jane
Abstract/Description
In the Caribbean region, calcareous shelled organisms are at risk of inhibited larval development (e.g., shell growth and mortality) at high ocean temperatures. Given predicted sea-surface temperatures due to global climate change for the year 2100 (by the IPCC and NOAA) researchers are predicting at what temperatures these changes could affect larval development of Queen conch, Lobatus (Strombus) gigas. Carbon emissions from human activities (e.g., burning of fossil fuels) are affecting...
Show moreIn the Caribbean region, calcareous shelled organisms are at risk of inhibited larval development (e.g., shell growth and mortality) at high ocean temperatures. Given predicted sea-surface temperatures due to global climate change for the year 2100 (by the IPCC and NOAA) researchers are predicting at what temperatures these changes could affect larval development of Queen conch, Lobatus (Strombus) gigas. Carbon emissions from human activities (e.g., burning of fossil fuels) are affecting marine organisms at multiple trophic levels due to ocean warming and acidification. L. gigas was abundant in their geographic range of the Caribbean Sea, the Gulf of Mexico, and around Bermuda, now with a combination of overharvesting and global climate change, conchs are candidates for the Endangered Species Act. As CO2 increases in the ocean, carbonate for calcium carbonate production decreases. L. gigas will use more energy to produce their shells (stunting growth rates) or opt for weaker shells. Researchers (Aranda and Manzano) reared L.gigas eggs from hatchling to settlement under five temperatures (28, 28.5, 29, 29.5, 30℃) to assess growth and development. At 30 ℃ larvae experienced faster growth rates, but survival was low (23%). While at 28 ℃ larvae had the highest survival (35%). Temperature seemed to have more of a direct impact on earlier stages of larvae of L. gigas than those closest to settlement. Queen conchs are economically important for their commercial value, being the second largest fishery in the Caribbean. Ocean warming and acidification would cause a decrease in harvest, changing prices for consumers. Urgent action against reducing greenhouse gas emissions must be taken. The Caribbean can mitigate contribution to greenhouse gases by renewable energy since it is an area that has great potential for hydro-electric, geothermal, wind and solar energy. This in turn could reduce the impacts to L. gigas larval development.
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Date Issued
2021-04-21
Identifier
BC3356
Format
Document (PDF)
PURL
http://purl.flvc.org/broward/fd/BC3356
Establishing a Long term Monitoring Plan for Hallandale Beach, Florida Nearshore Coral Reef Habitats.
Title
Establishing a Long term Monitoring Plan for Hallandale Beach, Florida Nearshore Coral Reef Habitats.
Name/Creator
Pollard, Madison Jane
Abstract/Description
The city of Hallandale Beach, Florida adopted the “Our Local Coral Reef Protection Ordinance” in June of 2019, with plans to restore their coastline and protect the community from future storm surges. Ordinance No. 2019 1- 011 added sections 5 to 8 in Chapter 13 "Health and Sanitation" of the city of Hallandale Beach code of ordinances, which outline strategies to protect and restore the resilience of the nearshore coral reef. Complex coral reef systems bring higher biodiversity and will...
Show moreThe city of Hallandale Beach, Florida adopted the “Our Local Coral Reef Protection Ordinance” in June of 2019, with plans to restore their coastline and protect the community from future storm surges. Ordinance No. 2019 1- 011 added sections 5 to 8 in Chapter 13 "Health and Sanitation" of the city of Hallandale Beach code of ordinances, which outline strategies to protect and restore the resilience of the nearshore coral reef. Complex coral reef systems bring higher biodiversity and will raise the economic value of the reef to tourism. The length of Hallandale Beach shoreline is approximately 0.80mi (4200ft). Acropora cervicornis (Staghorn coral), a critically endanger species, is said to be found ½ mile off the coast of Hallandale Beach and is an important reef-building species to be monitored. This proposal will establish a long-term monitoring plan and baseline for the nearshore coral reef based on the Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocols. It will briefly outline procedures needed to accomplish the three different monitoring surveys and important indicators each SCUBA diver will be required to record. Corals are the primary builders of reef habitats and they benefit from the presence of reef fish and benthic organisms. Reef fish have different eating habits that promote positive structure changes such as, keeping turf algae in check clearing room for recruitment of polyps. Benthic promotors such as, crustose coralline algae and minimal turf algae encourage a healthy reef habitat. According to a map of Broward County, Florida reef structure created by Brain Walker, the linear reef inner begins about 0.80 mi (4200ft) and the liner reef middle ends at about 1.75mi (9240ft) from the shore. There appears to be no linear outer reef off the coast of Hallandale Beach. There is no previous baseline to compare future surveyed data or confirm presence and density of diver sighted Acropora cervicornis. Baselines are important historical data that enables the city to identify changes in the complexity of the reef structure and responses to climate change to make proactive decisions. An initial baseline of Hallandale’s reef will be made to be comparable with future monitoring data, as well as determine the effectiveness of the management plans in place. AGGRA protocols require a minimum of six divers and with the use of city vendors, equipment costs can be as low as 230 dollars. Without a coral reef, the city may face costly damages from natural disasters such as hurricanes. Coral Reefs provide protection against storm surges that without, coastal erosion would increase and leave the city without an offshore defense against high energy wave action. AGRRA protocols will be applied to create a basic level survey easily adaptable, this will provide community building and outreach opportunities through citizen science and volunteering.
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Date Issued
2020-06-15
Identifier
BC746
Format
Document (PDF)
PURL
http://purl.flvc.org/broward/fd/BC746