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      <div align="center"><font color="navy" size="+4"><a
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      <div align="center"><font color="navy" size="+2">Atlantic Pearl Oyster (<i>Pinctada imbricata</i>)</font></div>
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      <div align="center"><font color="navy" size="+2">By Erin Leonhardt<br>
      <small>and<br>
James B. Wood (Ed)</small><br>
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	  Abstract 
	  <a href="Pinctadaimbricata.html#Taxonomy">Taxonomy</a>&nbsp; 
	  <a href="Pinctadaimbricata.html#Habitat">Habitat</a>&nbsp; 
	  <a href="Pinctadaimbricata.html#Ecology">Ecology</a>&nbsp; 
	  <a href="Pinctadaimbricata.html#RecentResearch">Recent Research</a>&nbsp;
      <a href="Pinctadaimbricata.html#Commercial">Commercial Importance</a>&nbsp;
      <a href="Pinctadaimbricata.html#Bermuda">Bermuda Laws</a>&nbsp; 
	  <a href="Pinctadaimbricata.html#Personal">Personal Interest</a>&nbsp; 
 	  <a href="Pinctadaimbricata.html#References">References</a>&nbsp; 
 	  <a href="Pinctadaimbricata.html#Links">Links</a>&nbsp; </font></div>
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<center><img src="images/Pinctadaimbricata.jpg" alt="Atlantic pearl oyster, Pinctada imbricata"></center>

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<font color="#330099" size="+2">Abstract</font><br>
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The Atlantic pearl-oyster, <i>Pinctada imbricata</i>, is biologically and economically important.  <i>Pinctada imbricata</i> is a filter-feeding bivalve that grows in a diverse geographic range (Urban, 2000; O Connor and Lawler 2004a).  The growth and reproduction of <i>P. imbricata</i> depends on salinity, temperature, suspended particulate matter (SPM), and food (Ward and MacDonald, 1996; Urban, 2000; O Connor and Lawler, 2004a).  Recent research on  <i>P. imbricata</i> focuses on commercial oyster farmers and shellfish hatcheries (O Connor and Lawler, 2004b).  In Bermuda <i>P. imbricata</i> is found in Harrington Sound and protected under Bermudian Laws(Balzer and Wefer, 1981; Laws of Bermuda, 1989; Urban, 2000).
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<font color="#330099" size="+2">Taxonomy</font><br>
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Phylum: Mollusca<br>
&nbsp;&nbsp;Class: Bivalvia<br>
&nbsp;&nbsp;&nbsp;&nbsp;Order: Pterioida<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Family: Pteriidae<br>
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The Atlantic pearl oyster, <i>Pinctada imbricata</i>, is in the class Bivalvia because it has bilateral symmetry, a two valved shell, is dorsally hinged, and has an intestine that passes through the heart (Sterrer, 1986).  The Atlantic pearl oyster lacks a head, radula, and cephalic eyes (Sterrer, 1986).  <i>P. imbricata</i> are in the order Pterioida because they have both a nacreous (pearl layer) and a notch in the right valve that byssally attaches to the substrate (Sterrer, 1986).  Characteristics that <i>P. imbricata</i> share in the family Pteriidae are an ovate shell, a straight hinge line, and an interior nacreous or pearl layer (Sterrer, 1986).  The species <i>Pinctada imbricata</i> is known for having a thin and brittle shell, appearing brown to tan with darker brown lines, and being able to produce pearls (Sterrer, 1986). 
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</a><a name="Habitat"><font color="#330099" size="+2">Habitat</font><br>
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The Atlantic pearl-oyster, <i>Pinctada imbricata</i>, has a broad range of habitats.  Common geographic locations that <i>P. imbricata</i> can be found are Australia (specifically New South Wales and Port Stephens), India, Caribbean Sea of Columbia (specifically Guajira province), and Bermuda (Urban, 2000; O Connor and Lawler, 2004a).   <i>P. imbricata</i> were brought to Japan to help improve economic loss due to disease in Japanese native pearl oyster species; furthermore, the introduction of <i>P. imbricata</i> to Japan led to cross-breeding between both pearl oysters species (Masaoka and Kobayashi, 2005).  Pearl oysters, including <i>P. imbricata</i>, were in abundance off the coast of Venezuela (primarily coast of Cubagua) until the early 1500s when high demands for pearls eventually depleted the pearl oyster population (Romero, 2003).  <i>P. imbricata</i> populations geographically vary depending on habitat conditions.
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The Atlantic pearl-oyster use byssi to attach to hard substrates (Ward and MacDonald, 1996).   <i>Pinctada imbricata</i> are found in rocky, sandy, and shallow areas in bays, sounds, lagoons, and harbors in both the Northern and Southern hemispheres (Ward and MacDonald, 1996; O Connor and Lawler, 2004a). 
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</a><a name="Ecology"><font color="#330099" size="+2">Ecology</font><br>
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Growth in <i>P. imbricata</i> embryos, juveniles, and adults is affected by seawater temperature changes, salinity fluxes, food availability, and suspended sediments (Ward and MacDonald, 1996; Urban, 2000; O Connor and Lawler, 2004a).  Temperature and salinity tolerance depends on the geographical location of <i>P. imbricata</i>; correspondingly, stable populations of <i>P. imbricata</i> are found near estuarine systems where water flow helps regulate salinity and temperature levels (O Connor and Lawler, 2004a).  When water flow is minimum during salinity changes bivalves can close their valves, this is called isoosmotic intracellular regulation (O Connor and Lawler, 2004a).  Juvenile Atlantic pearl  oysters responded to reduced salinities by closing their valves, which decreased the rate of byssal attachment (O Connor and Lawler, 2004a).  Under the conditions of 18 degrees Celsius and 29 to 32 parts per thousand (ppt) 80% of <i>P. imbricata</i> spat formed byssal attachment (O Connor and Lawler, 2004a).  One specific example is in Port Stephens, Australia where the temperature range for <i>P. imbricata</i> is 14 to 26 degrees Celsius and spawning primarily occurs during the summer when the temperature is above 18 degrees Celsius (O Connor and Lawler, 2004a; O Connor and Lawler, 2004b).  In India <i>P.imbricata</i> is tolerant of salinities between 24 to 50 ppt for 2 to 3 days; whereas, in Japan <i>P. imbricata</i> spat needs a minimum of 22.7 ppt to survive (O Connor and Lawler, 2004a).  Spawning of <i>P. imbricata</i> occurs at different temperatures because of the geographical area to which the species has adapted (O'Connor and Lawler, 2004a).   Temperature can also be affected by the amount of upwelling in an area, which can affect the rate of reproduction (Urban, 2000).  Upwelling can lower water temperature; correspondingly, upwelling increases surface nutrients supplying more energy for gonad development and reproduction (Urban, 2000).  The growth of <i>P. imbricata</i> is not only dependent on salinity and temperature, but also dependent on suspended particulate matter (Ward and MacDonald, 1996).
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<i>Pinctada imbricata</i> filter feeds suspended particulate matter (SPM) from the water column (Ward and MacDonald, 1996).  Abiotic factors such as storms and wind resuspend bottom sediments and increase the amount of SPM in the water; furthermore, an increase in SPM affects light penetration and nutrient levels (Ward and MacDonald, 1996).  High levels of sedimentation can clog the gills of <i>P. imbricata</i> (Ward and MacDonald, 1996).  <i>P. imbricata</i> is able to regulate the ingestion rate of SPM through bulk rejection and then reject the material in pseudofeces (Ward and MacDonald, 1996).  The purpose of pseudofecal production is not only to remove bulk amounts of excess or irritating material, but also to reject unwanted material to improve the quality of ingested matter (Ward and MacDonald, 1996).  Sediments contain varying levels of nutrients including nitrogen and carbon; nevertheless, <i>P. imbricata</i> does not select out nitrogen or carbon particles from SPM (Ward and MacDonald, 1996).  The amount of suspended matter has an affect on the growth of <i>P. imbricata</i> because of the amount of nutrients available in the SPM (Ward and MacDonald, 1996). 
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<i>P. imbricata</i> can be found in the subtropical environment of Harrington Sound, Bermuda (Balzer and Wefer, 1981; Urban, 2000).  Further studies need to be done on the number of <i>P. imbricata</i> in the sound and how the <i>P. imbricata</i> is ecologically affected.  Characteristics of Harrington Sound are large amounts of green algae (<i>Cladophora prolifera</i>), one inlet (Flatt s inlet) providing surface water flushing, a deep basin (Devil s Hole), and fish species primarily composed of grunts and sea-breams that transport sediments from deep to shallow water (Balzer and Wefer, 1981; Alheit, 1983; Lapointe and O Connell, 1989).  These ecological variables may effect the survival, growth, and reproduction of <i>P. imbricata</i> in Harrington Sound, but further studies need to done on correlating these variables with anthropogenic variables of Atlantic pearl-oyster populations in the sound.
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</a><a name="RecentResearch"><font color="#330099" size="+2">Recent
Research</font><br>
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Genetic techniques have been used to test the genes of Japanese oysters for identification purposes (Masaoka and Kobayashi, 2005).  <i>Pinctada imbricata</i> is considered genetically similar to <i>Pinctada martensii</i> and <i>Pinctada fucata</i> (both Indian-Pacific pearl oysters) (Masaoka and Kobayashi, 2005).  To replenish the loss of many Japanese native pearl oysters other pearl oyster species, including <i>P. imbricata</i>, were brought to Japan (Masaoka and Kobayashi, 2005).  This makes identifying pearl oyster species in Japan difficult because of the combination of many pearl oyster species (Masaoka and Kobayashi, 2005).
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Research on the reproduction and spawning of <i>P. imbricata</i> is used to benefit oyster farmers and shellfish hatcheries (O Connor and Lawler, 2004b).  In Port Stephens, Australia oyster spat was not available for farmers when the farmers needed the spat (O Connor and Lawler, 2004b).  To be economically successful, oyster farmers in Australia need spat in September, but <i>P. imbricata</i> was not ready till December or January; as a result, hatcheries were built to control oyster reproduction and spat availability (O Connor and Lawler, 2004b).  In the hatchery, oysters were conditioned in July and then spawned in August, which made spat available in September (O Connor and Lawler, 2004b).  Variables that were observed during reproduction and growth included shell growth, byssal attachment, mantle thickness, and mucoprotein layers (O Connor and Lawler, 2004b).  O Connor and Lawler (2004b) found that <i>P. imbricata</i> commonly has two reproduction peaks, sometimes one or three peaks, and peaks usually occur in the summer. Reproduction varies depending on the latitude of the area; furthermore, spawning activity was found to decrease when latitude increased (O Connor and Lawler, 2004b).  Researching reproduction is important because the information will help farmers know when to collect wild spat and spawn oysters in the hatchery (O Connor and Lawler, 2004b). 
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</a><a name="Commercial"><font color="#330099" size="+2">Commercial
Importance</font><br>
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In the early 1500 s there were many oyster beds containing <i>P. imbricata</i> off the coast of Venezuela, the coast later became know as Costa de las Perlas (Pearls  Coast) (Romero, 2003).  Trade between indigenous people and European settlers not only kept pearls in high demand, but also led to pearls becoming an unsustainable resource (Romero, 2003).  Pearls from oysters were the most valuable commodity carried on Spanish ships and were in high demand by wealthy people (Romero, 2003).  Prior to the year 1530 the value of pearls shipped from the American continent to Europe was one-third greater than the production of gold and silver mines on the American continent in a year (Romero, 2003).  As the demand for pearls increased the supply quickly decreased resulting in the depletion of pearl oyster beds off the coast of Venezuela (Romero, 2003).   
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Even though pearl oyster beds off the coast of Venezuela were depleted, pearls remain economically important in many places.  In Australia pearl oysters are the primary basis for the Australian aquaculture industry (O Connor and Lawler, 2004b).  Other than Australia, <i>Pinctada imbricata</i> is economically important in Japan (O Connor and Lawler, 2004b; Masaoka and Kobayashi, 2005). 
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</a><a name="Bermuda"><font color="#330099" size="+2">Bermuda Laws</font><br>
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In 1978 Bermuda Fisheries Laws declared the Atlantic pearl-oyster, <i>Pinctada imbricata</i>, as a protected species (Laws of Bermuda, 1989).
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</a><a name="Personal"><font color="#330099" size="+2">Personal Interest</font><br>
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My interest in oysters began while studying at college.  Through my university I was fortunate enough to work for an oyster gardening program that aims to restore and enhance the oyster population in Narragansett Bay, Rhode Island USA.  Oyster populations are biologically important because they filter large amounts of water per day and provide habitats for other organisms to live underneath or around.  While studying in Bermuda I learned that in Bermuda the Atlantic pearl-oyster is primarily found in Harrington Sound and immediately became interested as to why they were mainly found in the sound.  I became interested in what the population size of these oysters in the sound may be and what effects the population size of these oysters.  I learned that the Atlantic pearl-oyster is not only biologically important, but also economically important in many cultures.  The combination of biology and anthropology makes the discussion of the Atlantic pearl-oyster even more intriguing and valuable to the earth and society.   
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</a><a name="References"><font color="#330099" size="+2">References</font>
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Alheit J.  1983.  Sediment transport by fishes in Harrington Sound, Bermuda.  Estuaries, 
	Coastal and Shelf Sciences.  17:547-554.
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Balzer W, Wefer G.  1981.  Dissolution of carbonate minerals in a subtropical shallow 
	marine environment.  Marine Chemistry.  10:545-558.
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Lapointe BE, O Connell J.  1989.  Nutrient-enhanced growth of <i>Cladophora prolifera</i> in 
	Harrington Sound, Bermuda:  Eutrophication of a confined, phosphorous-limited 
	marine ecosystem.  Estuarine, Coastal and Shelf Sciences.  28:347-360.
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Laws of Bermuda.   Fisheries (Protected Species) Order 1978  1989.  Accessed Nov 
	11th.  2007 <http://www.laws.gov.bm/>.
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Masaoka T, Kobayashi T.  2005.  Species identification of <i>Pinctada imbricata</i> using 
	intergenic spacer of nuclear ribosomal RNA genes and mitochondrial 16S 	ribosomal 	RNA gene regions.  Fisheries Science.  71:837-846.
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O Connor WA, Lawler NF.  2004a.  Salinity and temperature tolerance of embryos and 
	juveniles of the pearl oyster <i>Pinctada imbricata</i> Roding.  Aquaculture.  229:493-		506.
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O Connor WA, Lawler NF.  2004b.  Reproductive condition of the pearl oyster, <i>Pinctada 
	imbricata</i>, Roding, in Port Stephens, New South Wales, Australia.  Aquaculture 		Research.  35:385-396.
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Romero A.  2003.  Death and taxes:  the case of the depletion of pearl oyster beds in the 
	sixteenth-century Venezuela.  Conservation Biology.  17:1013-1023.
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Sterrer, W.  (1986). Marine Fauna and Flora of Bermuda (ed. W. Sterrer), pp. 460-467.  Canada:  John Wiley & Sons, Inc.
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Urban HJ.  2000.  Culture potential of the pearl oyster (Pinctada imbricata) from the 
	Caribbean.  I.  Gametogenic activity, growth, mortality and production of a 		natural population.  Aquaculture.  189:361-373. 
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Ward JE, MacDonald BA.  1996.  Pre-ingestive feeding behaviors of two sub-tropical 
	bivalves (<i>Pinctada imbricata</i> and  <i>Arca zebra</i>):  Responses to an acute increase in 
	suspended sediment concentration.  Bulletin of Marine Science.  59:417-432. 
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</a><a name="Links"><font color="#330099" size="+2">Links</font>
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</font></a><font color="#330099" size="+1"><a href="INSERT%20LINK"></a>
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<a href="http://www.australian-aquacultureportal.com/industrygroups/pearls.html">Australian Aquaculture Portal, <i>Pinctada maxima</i>
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<a href="http://findarticles.com/p/articles/mi_m3089/is_1_65/ai_n6272151">History of the Atlantic pearl oyster, <i>Pinctada imbricata</i>, industry in Venezuela and Colombia</a>
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<a href="http://www.aquaculturecouncilwa.com/how_to_get_into_aquaculture/pearl_oysters">Pearl Oyster Aquaculture</a>
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<a href="http://www.lib.noaa.gov/japan/aquaculture/report1/kanno.html">The Present Status of Shellfish Culture in Japan</a>
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<a href="http://www.encyclopedia.com/doc/1G1-65133665.html">A History of the Pearl Oyster Fishery in the Archipielago de las Perlas, Panama</a>
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