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Blair_Frantz_Conch Biodiversity - Marine Protected Areas vs Non-Protected Areas FINAL

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    Blair Frantz

    Dr. Tamsen Byfield

    Marine Protected Areas: Management Techniques & Policies

    SFS 3510

    June 23, 2014

    Email: [email protected] or

    [email protected]

    Abundance and Biodiversity of Queen Conch (Strombus gigas) in Marine Reserves vs. Non-

    Reserves

    1. Introduction:

    The mollusk, known internationally as the Queen Conch or Pink Conch, and scientifically

    as Strombus gigas of the Strombidae family, is a Caribbean marine animal of great importance to

    the diet and livelihood of thousands of families throughout the Caribbean. Conch are found in

    shallow, clear water at depths generally less than 30 meters. Conch are limited to that depth

    range by limits in seagrass and algae cover, as food sources. Seagrass meadows, coral rubble,

    algal plains, and sandy substrates are the preferred habitat for conch (McCarthy, 2007).

    Queen Conch has high commercial fishery value and is commercially threatened. The

    large beautiful shell has been prized by tourists in recent years, but was previously valued more

    for its meat. Queen Conch have provided a staple meat source in the Caribbean region for

    centuries and in recent times have been extensively overfished for this reason. Their flesh is also

    used as fishing bait and the shells can be sold for the tourist trade. The tendency of conch to

    aggregate in shallow waters in order to spawn in the summer months has made the species

    vulnerable. The increase in fishing pressure caused by its rising commercial value since the

    1970's has caused Queen Conch populations to decline throughout their distribution range. This

    is largely due to the slow maturation growth cycle (three to four years) of the Queen Conch. At

    this rate, conch populations are unable to offset the development of fisheries technical

    enhancements allowing them to catch larger quantities and at previously unobtainable depths

    (Gascoigne, 2005).

    mailto:[email protected]:[email protected]

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    Queen Conch face many other threats such as habitat loss, poaching, habitat management

    and critical depensation threshold and tourist potential. Damage to key areas of habitat,

    particularly mangrove and seagrass beds have reduced the availability of nursery areas for young

    conch. Poaching, in combination with legal take can prevent populations of conch from

    recovering. Habitat management for juvenile conch is very specific, therefore making

    management difficult. Juvenile conch habitat is suspected to be shallow, with turtle grass,

    Thalassia testudinum beds. Critical depensation threshold: when Queen Conch populations drop

    below a critical density point, reproduction ceases to be effective. Queen Conch rely on high

    density breeding populations for successful breeding. An unsustainable conch population cannot

    be considered healthy until population density has significantly increased above current levels. If

    an unsustainable population should ever fall below the critical depensation threshold, intensive

    restoration management will be required for basic stock maintenance. The final threat involves

    tourist potential. As availability of conch becomes limiting, demand for conch meat and shell

    products may be expected to become greater (Queen conch Strombus gigas, 2010).

    The Queen Conch is listed on Appendix II of the Convention on International Trade in

    Endangered Species (CITES), thus requiring an export permit for trade to occur. In 1996, the

    countries within this conchs range recognized the importance of the species and adopted an

    International Queen Conch Initiative to promote a common international management strategy

    for the queen conch resource in the Caribbean region. It has been suggested that harvesting limits

    or marine reserves will allow the species to recover from overfishing (Gascoigne, 2005). There is

    sufficient evidence that over fishing negatively affects ecosystems, therefore a reduction in

    fishing is the mainstay of fisheries- model case studies predicting that the establishment of

    marine protected areas (MPAs), especially for overexploited populations, can mitigate ecosystem

    effects of fishing; reserve protection should increase biomass and density (Marine Fishing

    Strombus Gigas, 2013).

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    Specifically, in South Caicos of Turks and Caicos Islands (TCI) reef degradation and

    depletion of fisheries has impacted the livelihood of the local community. Presently the South

    Caicos economy is based on tourism and fisheries- primarily conch. Unsustainable and

    destructive fishing practices in combination with increased human activity threaten coastal

    habitats and the organisms and industries that they support. Increased tourism and the creation of

    the infrastructure that supports this industry often have deleterious effects on the environment.

    An increase in tourism and coastal development will lead to increased demand for marine

    resources such as the Queen Conch. In addition, climate impacts on local ecosystems will greatly

    impact the fishing industry. The TCI has an extensive network of 34 protected areas including

    Tuckers Reef and Admirals Aquarium. These marine reserves in South Caicos are established to

    ensure the sustainability of natural and historic resources- such as the Queen Conch. However,

    lack of scientific knowledge, local understanding and personal and environmental stewardship

    hinders effective management of resources and the effectiveness of these protected areas (Turks

    and Caicos, 2014).

    Dilemma: do marine reserves really work? How can we best ensure sustainable fisheries?

    This study focusses on conch dispersal, biodiversity, maturation, depth and habitat in reserve

    areas vs. non reserve areas within the South Caicos area of TCI. The marine reserve in South

    Caicos where this research was conducted was East Harbour Lobster and Conch Reserve. The

    results from this field work can be used by scientists to better protect the high densities of native

    adult Queen Conch using methods such as marine protected reserves, and more. The Queen

    Conch (S. gigas) will be protected, be more abundant and have greater biodiversity in marine

    reserve areas vs. non marine reserves provided effective resource management and conservation

    programs, which include networks of sustainable protected areas are effectively maintained

    throughout the TCI and entire Caribbean region. It is also hypothesized that the density of conch

    outside marine reserves will not be high enough for mating to occur because there are not enough

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    adult conch as a result of overfishing, and most adult conch will be found in seagrass areas or

    algal cover habitats, as identified in previous studies as their preferred habitat due to essential

    grazing needs.

    2. Method:

    The objective of this study was to assess the status of Caicos Bank benthic communities in

    protected vs. non-protected sites in South Caicos. The field work was conducted at marine

    reserve sites (East Harbour Lobster and Conch Reserve) which included Admirals Aquarium,

    Tuckers Reef and HDL. The three non-marine reserve sites surveyed included AJ11, the south

    end of Long Cay and Dryers Reef (Figure 1). This study was conducted by students from The

    School for Field Studies (SFS) over a two-day period from June 19 20, 2014.

    Figure 1. Map of surveyed areas of South Caicos.

    During team field research vertebrates, invertebrates and the habitat organisms were

    studied. Some key macro- invertebrates observed and recorded included sea urchins: Diadema

    antillarus and Tripneustes ventricosus. Conch observed and recorded included the Queen Conch

    and Strombus costatus. Lobster observed and recorded included Panulirus argus. If Queen

    Conch was observed it was noted and recorded if the conch had a flared or roller lip. The

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    significance of this observation was used for determining maturity of the conch. In younger

    specimens of Queen Conch, the absence of a flared lip was an indication that the observed

    animal had not reached sexual maturity (Figure 2).

    Figure 2. Image of Queen Conch (Strombus gigas) exhibiting flared lip.

    From: http://www.fishwatch.gov/seafood_profiles/species/conch/species_pages/queen_conch.htm

    The type of habitat where these invertebrates were observed and found was also recorded.

    The five classes of habitat noted in our observations included sandy plain, algal plain, seagrass,

    coral and rubble (Figure 3).

    Figure 3. Image of Queen Conch (Strombus gigas) in seagrass.

    From: http://www.fishwatch.gov/seafood_profiles/species/conch/species_pages/queen_conch.htm

    http://www.fishwatch.gov/seafood_profiles/species/conch/species_pages/queen_conch.htmhttp://www.fishwatch.gov/seafood_profiles/species/conch/species_pages/queen_conch.htm

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    Data were collected using visual belt transects and quadrat surveys. Quadrat surveys and visual

    belt transect surveys were used to collect ecological data in a standardized way. These sampling

    methods provided more accurate data than random sampling or simply guessing; they also took

    less time than counting every specimen within a specific area. Both transects and quadrats were

    used to determine the diver