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Venerupis galactites (Lamarck, 1818), an endemic Australian infauna! venerid clam, is morphologically/ anatomically described based on specimens collected in shallow-water Posidonia australis seagrass beds in Esperance Bay, Western Australia. The species lives in high densities (1 ,300/m2) in 2-4 cm sediment depth, byssally attached to the seagrass rhizome mats. Notable features of its anatomy include elongated siphons that are united nearly to the tip, expansive plicated gills, and a prominent byssal groove on the posteroventral foot. The byssal gland in histological sections is irregularly ovoid and cupulate, with a narrow lumen; the microfibrillar ribbon-like byssus forms a single thick proximal stalk that divides distally into 2- 3 branches. Each branch can have numerous periodic, flat and parallel side-branches that extend from one side of the primary byssal thread and terminate in attachment plaques. The form of the byssus is reflected in the byssal duct, which has an infolded secretory epithelium that forms or molds the side branches. Byssal attachment by adult clams is discussed for the largely free-living and infauna! family Veneridae, a group in which neotenous retention of this postlarval feature was thought to be restricted to intertidal rock nestlers. Rather than representing a simple retention of neotenous features, the elaborate byssal apparatus of V galactites is clearly derived. The parallel side branches seen along a single side of the primary byssal threads could reflect an adaptive feature for secure adhesion in an infaunal life mode nestled along relatively narrow, cylindrical rhizomes.

Hardelams, Mercenaria mercenaria (Linne, 1758), tagged with brass washers attached to the outer shell surface and replanted into their natural habitat, were located remotely through the use of a commercially available, fully submersible, pulse technology metal detector. The ability to remotely locate tagged, replanted clams can increase the speed and efficiency of field operations associated with studies of clam population dynamics. Also, this methodology can reduce localized disturbances to the habitat that routinely accompany extensive hand probing to relocate experimental clams in traditional tag and recapture based studies.

Collections of 108 species of marine and estuarine mollusks from and around Assateague Island, Maryland and Virginia, from 1991 to 1996, vary from and extend the known species lists generated by three previously published collections over the past 100 years. Extensive sampling, including benthic grabs, trawls, and hand collecting, has added 54 species of mollusks (20 bivalves, 31 gastropods, one polyplacophoran, and two cephalopods) to the 1914 list of Henderson & Bartsch and 46 (19 bivalves, 26 gastropods and one cephalopod) to that of Counts & Bashore from 1991. Homer et al. in 1997 provided a mollusk survey of Maryland coast bays and listed 73 molluscan species (including 10 species recorded as shells only and eight as taxonomic uncertainties). To the latter we have added 51 molluscan taxa they did not find (19 bivalves, 29 gastropods, one polyplacophoran, and two cephalopods). All collections represent a total described malacofauna of this region of 146 shallow-water species excluding undescribed or non-described taxa in earlier papers. Within the populations of some of the species collected were a few exceptionally large individuals, adding to previous records of unusually large specimens of mollusks from this region of the Atlantic coast. Additionally, some species of mollusks (Tectura testudinalis, Eupleura semisulcata [Gastropoda], Tridonta borealis [Bivalvia]) and some non-mollusks (the ascidian Ecteinascidia turbinata and a confirmation of an extension of the anthozoan Peachia parasitica) have been found in the waters surrounding Assateague, well outside of their previously reported geographic ranges. The results of the present study suggest the need for a re-evaluation of possible environmental shifts that could have taken place since the collections of the early 1900s and have elsewhere been implicated in the change of malacofauna of Assateague Island since that time. Additionally, range extensions reported could reflect a subtle geographic transition zone, newly introduced species, or, most likely, an understudied coastal area.

The anomalodesmatan family Laternulidae represents a group of bivalves with a very few well-known taxa and many more poorly known taxa. Laternula rostrata (G. B. Sowerby, 1839) and L. anatina (Linnaeus, 1758) occur in close proximity to each other in and along the margins of mangroves of Kungkrabaen Bay, Thailand. Laternula rostrata resides in soft to sandy sediments often within the interstices of mangrove roots located in more open portions of the mangrove mud flat. Laternula anatina lives deeper in the mangrove in more protected environs. Laternula anatina is a smaller bivalve that has a variable shell outline, sometimes a wrinkled shell appearance, thicker periostracum, and frequently extensive umbonal erosion. Both species have high concentrations of external shell spinules anteriorly and closer to the umbos (i.e., in juvenile shell) reflecting functionality in retaining an infaunal position. The larger L. rostrata is thinner shelled and more fragile; has more distinct and longer shell spinules composed of flattened lathes; a glossy external appearance; a longer umbonal slit; and a deeper pallial sinus. Additionally, L. rostrata has a saddle-shaped lithodesma; a lithodesma is absent in L. anatina as is typical of most laternulids. Shell microstructure of both is prismatonacreous, typical of the group, but the prismatic layer is thin and appears truncated into small blocky and/or granular columns in transitional zones. The bulk of the shell is tightly packed sheet nacre. The growth lines in L. rostrata, more pronounced but fewer in number than in L. anatina, appear as shallow rolling “hills” in both the shell and chondrophore. The differences in shell microstructure in these two species are specific to the taxa but based on different habitats and burrowing depths, albeit within the confines of a tropical mangal, could represent biomineralization events that reflect environmental adaptations. Variations in the thickness of the microstructural shell layers of four species of laternulids is compared and we speculate on possible functional and/or environmental relevance of these differences.

Barbour's Pond is a 4.45-ha pond located in Garrett Mountain Reservation in Passaic County in northern New Jersey, one of the most densely populated regions in the United States. Despite its small size and surrounding urban sprawl, the shallow waters of this pond hold 18 species of molluscs. Monthly samples from March 2004 through March 2006 found the highest diversity in December 2004, and in January, June, and July 2005. Additional samples were taken in April 2007 and May 2010 to spot-check relative diversity years after the original sampling period. Total molluscan abundance was greatest in July and November 2004, possibly reflecting new late spring and autumn cohorts. Univariate statistics demonstrate that this pond has a temporally stable and diverse malacofauna. Analysis, of basic environmental parameters including temperature and pH, however, showed little correlation with molluscan diversity over time, underscoring the stable yet complex nature of biodiversity of this small urban pond.

St. Catherines Island is one of several barrier islands lining the coast of Georgia, USA. This island is among the least recently anthropogenically impacted of the Georgia Sea Islands, but had not previously been examined in detail for coastal invertebrate macrofauna. From 1992 through late 1998 a coastal survey was conducted that examined the diverse marine invertebrate fauna of St. Catherines Island. Salt marshes, sand flats, mid- to low-energy sand beaches, beach wood debris, tidal creeks, shallow benthos, and artificial hard substrata (including docks) were qualitatively sampled for macroinvertebrates. Over 340 species were identified. Crustaceans composed close to 40% (14% amphipods; 15% decapods), polychaetes 17.5%, and molluscs about 25% of all species recovered. These results are compared to the few other relevant studies from the United States mid-Atlantic Coast.

Aqueous-phased xenobiotic contaminant exposure can biochemically modify newly generated periostracum of the Asian freshwater bivalve,Corbicula fluminea. Laser-induced desorption of partially polymerized periostracum produces spectra distinguishable from mass spectral images generated from uncontaminated periostracum. Organic xenobiotic contamination putatively impedes full polymerization of the periostracin protein. The detection of the effects of pollution on periostracum by the laser microprobe mass analyzer constitutes a novel bioprobe for the definitive but qualified detection of xenobiotic contamination.

Episodic events which affect populations of marine invertebrate species are rarely documented. We report the catastrophic mass exhumation and deposition of a large aggregation of adult bivalves (Mulinia lateralis [Say, 1822]) to a suboptimal habitat on a sandy intertidal beach of St. Catherines Island, Georgia, USA. The displaced population impacted a large area (7000 m2) of the beach and consisted of similar-sized clams (∼ 13 mm mean shell length). We suggest that the exhumation could have been a result of storm-induced shear stress, an hypoxic event, or other environmental stress on the individuals. Events of this type could have important implications for population dynamics and cohort distribution, fisheries predictions and harvests, and interpretation of fossil assemblages.

Temperature is a determinant environmental variable in metabolic rates of organisms ultimately influencing important physiological and behavioural features. Stressful conditions such as increasing temperature, particularly within high ranges occurring in the summer, have been suggested to induce flotation behaviour in Corbicula fluminea which may be important in dispersal of this invasive species. However, there has been no experimental evidence supporting this hypothesis. It was already proven that C. fluminea drift is supported by a mucilaginous drogue line produced by mucocytes present in the ctenidia. Detailed microscopic examination of changes in these cells and quantification of clam flotation following one, two and three weeks of exposure to 22, 25 and 30°C was carried out so that the effects of increasing water temperatures in dispersal patterns could be discussed. Results show that changes in temperature triggered an acceleration of the mucocytes production and stimulated flotation behaviour, especially following one week of exposure. Dilution of these effects occurred following longer exposure periods. It is possible that these bivalves perceive changing temperature as a stress and respond accordingly in the short-term, and then acclimate to the new environmental conditions. The response patterns suggest that increasing water temperatures could stimulate C. fluminea population expansion.

Freshwater unionid mussels produce a bilayered shell with the mineral proportion comprising an outer prismatic and an inner nacreous layer. The shell is the animals’ primary structural means of protection from predators and environmental challenges; therefore, variations in shell strength and properties may lead to differences in survival. Few studies have systematically assessed shell properties in unionids. A major challenge in such work is separating effects of environment from those of evolutionary history, because ultimately, both can affect shell properties. We collected eight species of unionids within a small area of the Allegheny River, Pennsylvania, that was relatively homogeneous in substratum type and other environmental characteristics. For each species, we quantified shell thickness, including thickness of the prismatic and nacreous layers, and shell micromechanical properties (microhardness and crack propagation, a measure of fracture resistance) in three regions of the shell. Shell thickness varied dramatically among species and was about five times greater in the thickest-shelled species, Pleurobema sintoxia, than in the thinnest-shelled species, Villosa iris. Because all species experienced similar environmental conditions, variation in shell thickness can be attributed largely to evolutionary history. In contrast, microhardness and crack propagation showed little variation among species. Given that micromechanical properties are similar among species, shell strength may be largely a function of thickness. These results have conservation implications, as differences in shell thickness could reflect relative vulnerability to predators and physical conditions

The Asian isopod Ianiropsis serricaudis is now well established in fouling communities, often associated with introduced ascidians, throughout the Northern Hemisphere but has gone largely unnoticed because of its diminutive size (typically less than 3 mm in length) and the difficulties of identifying small peracarid crustaceans. Known locations include the northeastern Pacific (Puget Sound, San Francisco Bay, and Monterey Bay), the northwestern Atlantic (from the Gulf of Maine to Barnegat Bay, NJ), and the northeastern Atlantic (England and the Netherlands). We predict that this species is widespread along North America and European coasts, and may already be introduced to cold temperate waters of the Southern Hemisphere as well.