experience lower predation pressure presumably due to a thicker shell. The largest clams are quahogs or chowders and cherrystones; they have the toughest meat and are used in such dishes as clam chowder, clam cakes, and stuffed clams, or are minced and mixed into dishes that use the smaller, more tender clams. Brood-stock management is a vital step in fulfilling the potential of hard clam aquaculture. The greatest concentration of razor clams is found on the 53-mile stretch of shore on Washington State’s southern coast, where the flat, sandy beaches make an ideal habitat. 1975. In the United States, hard clams have the highest dollar value of commercially harvested clams. For the lighthouse, see, "Quahog" redirects here. New York Sea Grant, 2009; Handbook for Developing Watershed Plans to Restore and Protect Our Waters, EPA 2008 margins. Habitat suitability index models. South Carolina clams are ready to spawn at Fish and Wildlife Service taking? While conservation and protection of existing hard clam habitat is the best strategy for addressing this problem, restoring areas that supported hard clams in the past is a valuable management measure. 3–51, in Kraeuter, J. N. and M. Castagna (eds.) Older literature sources may use the systematic name Venus mercenaria; this species is in the family Veneridae, the venus clams. water temperatures in the spring, when temperatures reach approximately 20°C. in the water. The two species are closely related, produce viable hybrids … secrete the substances that make up the clam's shell. In the South Atlantic, hard clams are common in estuaries Clams have two-part shells and are usually found either in their marine habitat or in freshwater sources like rivers. provides concurrent observations of habitat (sediment type, and presence/absence of eelgrass), and hard clam size-frequency distribution and abundance. In South Carolina, the Quahog parasite unknown (QPX)[6] is a parasite that affects the hard shell clam Mercenaria mercenaria. In many areas where aquaculture is important, clam farmers have bred specialized versions of these clams with distinctions needed for them to be distinguished in the marketplace. Northern Quahog or Hard Clam (Mercenaria mercenaria) Habitat Suitability 5 This soil interpretation does not include the minor soil components or inclusions. extends from spring until fall, with a pause during midsummer months. The hard clam is eaten by crane, sea stars and other animals larger than it. They can burrow up to 15 centimeters below the substrate surface and occur … What is the range of the Suwannee moccasinshell? United States Department of Interior, Hard clams prefer sandy to muddy bottoms, especially Habitat: Hard-shell clams occur mainly in bays and estuaries along the coast, from the intertidal zone to depths of about 18 m (60 ft). Hard clams are found in intertidal and subtidal areas from Nova Scotia, Canada to Florida. Predator type and abundance were reported from 1978 to 1981 and 1991 to 2003, which represents those containing shell fragments near areas with turbulent currents and relatively high salinity. For example, the species is an important member of the suspension-feeding, benthic fauna of the lower Chesapeake Bay. More than 15,000 living species of bivalves are known, of which about 500 live in fresh water; the others occur in all seas. Habitat: Burrows just below the sand intertidally and subtidally. "Systematics and taxonomy, Chapter 1", pp. Today people living in coastal New England still use the Native American word for the clam as they have done for hundreds of years. A hatchet-shaped foot and two short siphons periodically extend from inside the clam. Waste or Abuse to SC Inspector General. Clams from such waters are transplanted to clean bay waters or processed in a state-approved depuration plant for purification. Relative abundance of, "Influence Of Host Genetic Origin And Geographic Location On Qpx Disease In Northern Quahogs (=Hard Clams), Mercenaria Mercenaria", 10.2983/0730-8000(2007)26[109:IOHGOA]2.0.CO;2, https://en.wikipedia.org/w/index.php?title=Hard_clam&oldid=991799161, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 1 December 2020, at 21:51. Along the Atlantic coast, clams inhabit estuaries from the Gulf of St. Lawrence, Canada, to Florida. wildlife habitat, and preserve the natural beauty of Maine’s shoreline areas. The inner shell surface is shiny with a purplish-blue tinge around the muscle scars. Hard Clam Relay and Depuration The relay and depuration programs allow hard clams from moderately polluted waters to be utilized. Hard clams do not migrate, so any disturbance may cause long-term population effects. The model is scaled to produce an index of habitat suitability between 0 (unsuitable habitat) and 1 (optimally suitable habitat) for the Atlantic and Gulf coasts of the United States. Dead shell accumulations Accumulation of shells from dead mollusks or other invertebrates in sufficient quantities to be the Phone Numbers | Accessibility | The greatest concentration of razor clams is found on the 53-mile stretch of shore on Washington State’s southern coast, where the flat, sandy beaches make an ideal habitat. Quahog (Mercenaria mercenaria)Alternate common names: Hard-shell Clam, Cherrystone, Littleneck. Large particles that the clam cannot eat are Each female clam may release between 2 and 25 million eggs during a spawning season, depending on its A similar species, the Southern quahog (Mercenaria campechiensis), lives in coastal waters from North Carolina south to Florida and Texas. wildlife habitat, and preserve the natural beauty of Maine’s shoreline areas. Hard clams can bury to an average depth of 2 cm (1 in) in sand and 1 cm (0.5 in) in mud, with smaller Bivalves usually live on or in sandy or muddy bottoms. Two species of hard clam are found in Florida: the northern quahog (Mercenaria mercenaria) and the southern quahog (Mercenaria campechiensis).Historically, clams … The quahog is the official shellfish of the U.S. state of Rhode Island. Hard Clam Relay and Depuration The relay and depuration programs allow hard clams from moderately polluted waters to be utilized. It should be noted that these maps do not include undocumented, regulated shellfish areas. digested food pass out the exhalent siphon as fecal pellets. and sand on top. Like other clams, it is a filter feeder. Clam is a common name for several kinds of bivalve molluscs.The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds.Clams have two shells of equal size connected by two adductor muscles and have a powerful burrowing foot. Hard clam density in Chesapeake Bay is positively associated with increasing sediment grain size; 78% of all clams collected were found in shell or sand habitats. Information and Education Series. along the Gulf coast to the Yucatan Peninsula in Mexico. [7] This research is fueled by the need to inform aquaculturists, who suffer financially because of the mortality rates in clams that QPX inflicts and the ensuing years in which runs must be left fallow to clear the disease. Designating 539 river miles of critical habitat across 16 units. that are partly closed by oyster beds at the mouth appear to be one of the more productive habitats for this species. After about 10 hours, the embryo hatches and goes through a series of developmental stages before FOIA | Privacy Policy | Report Human also eat clams. umbo. from the intertidal zone to depths of about 15 meters (50 ft) or more. It took about 50 years of relentless dredging to wipe out these clam beds. The word comes from the Narragansett word "poquauhock", which is similar in Wampanoag and some other Algonquian languages; it is first attested in North American English in 1794. Sometimes littlenecks are steamed and dipped in butter, though not as commonly as their soft-shelled clam cousin the "steamer". Oyster Investigation — Atlantic Coast Similar to oysters, the presence of other clams in the sediment induces The hard clam, Mercenaria mercenaria, burrows shallowly in sediments of either mud or sand.It is among the most commercially important species of invertebrate. There are numerous commercially important clam species within the United States, though the one most recognized and utilized in shellfish aquaculture operations on the East coast is the quahog or hard clam (Mercenaria mercenaria). under three categories based on size: littlenecks are the smallest and most expensive, cherrystones are medium-sized; webmaster@dnr.sc.gov, ACE Characterization Study Species Gallery, Report Littlenecks are often found in-the-shell in sauces, soups, stews, and clams casino, or substituted for European varieties such as the cockle in southern European seafood dishes. Originally bred in the warm water outflows at Southampton Power Station for use as eel bait, the population became self-sustaining and can now be found in Southampton Water and has also spread to Portsmouth Harbour and Langstone Harbour. The most distinctive of these names is quahog (/ˈkoʊhɒɡ/ KOH-hog, /ˈkwɔːhɒɡ/ KWAW-hog, or /kwəˈhɒɡ/ kwə-HOG). This decline cannot be attributed to any one specific reason, but is probably the result of habitat Keith, W. J. and W. D. Anderson. Small tidal creeks settling on the substrate. [9] The Narragansetts used the hard clam for food and ornaments.[10]. Hard clam habitat in the Bay is continually threatened and disturbed by activity associated with shoreline and industrial development (e.g., dredging for ship-ping and dock access). In 2007, the Maryland state [1], In fish markets, there are specialist names for different sizes of this species of clam. Food trapped The Clam is the primary consumer who eats the producer. Life History and Behavior These long-lived, dense-shelled bivalves live in sandy or muddy bottoms throughout Florida waters. to dark brown or black. The smallest legally harvestable clams are called countnecks or peanuts, next size up are littlenecks, then topnecks. Each clam filters up to 3.8 liters of water per hour, regulating water clarity, cycling nutrients, 1 and making areas more resistant to harmful algal blooms. Once mature, clams ecosystem services and to increase structural marine habitat complexity, particularly when compared to adjacent, barren mud-bottom. Waste or Abuse to SC Inspector General | © 2020 All rights reserved. Fish and Wildlife Service, Washington, DC. Hard clams prefer sandy to muddy bottoms, especially those containing shell fragments near areas with turbulent currents and relatively high salinity. Hard clam density in Chesapeake Bay is positively associated with increasing sediment grain size; 78% of all clams collected were found in shell or sand habitats. The native range for hard clams extends from the Gulf of St. Lawrence down along the East Coast of the United States to Florida into the Gulf of Mexico to Texas. These are known as the notata strain of quahogs, which occur naturally in low numbers wherever quahogs are found.[5]. A hard clam also possesses a hatchet-shaped foot that it uses to move around and bury itself in the mud. The shallow water habitat required for most techniques places hard clam culture in a highly visible location and in a zone where there can be interactions with sea grasses. The hard clam aquaculture industry plays an-other significant role in preserving and enhancing the hard clam industry in New Jersey. Successful ... softshell and hard clam resources in order to illustrate the relation of these resources to streams and shoreline areas vital to their conservation. Thraustochytrids are common protists in marine sediments and the water column, but only a few thraustochytrids are known as parasites of marine animals. Description. It reproduces sexually by females and males shedding gametes into the water.[2]. [11][12] Filter-feeding shellfish are affected, such as clams, oysters, and mussels. WWWWWWW WWWWWWW Its DNA sequence analysis places the QPX parasite among the thraustochytrid stramenopiles. They are found in a variety of substrates, but prefer sandy bottoms, especially with shell. same regulations that apply to the harvest of oysters apply to the harvest of clams. hard clam habitat is the best strategy for addressing its risk of loss, restoring areas that supported hard clams in the past is a valuable management measure. They prefer muddy bottoms with loose shell Pitar citrinus They are considered edible but have become somewhat true. "Biology of the Hard Clam", Eldridge, P.J., W. Waltz, and H. Mills. Habitat requirements for the hard clam, Mercenaria mercenaria, in Chesapeake Bay . [3][4] New England tribes made valuable beads called wampum from the shells, especially those colored purple; the species name mercenaria is related to the Latin word for commerce. [11] Some other kinds of algal blooms make the seawater appear red, but red tide blooms do not always discolor the water, nor are they related to tides. [11], A species of bivalve mollusc native to the east coast of North and Central America, "Cherrystone" redirects here. benthic existence 20 to 60 days after hatching. the internal organs. Similar to American oysters, clams perform the important ecological role of The hard clam, Mercenaria mercenaria, is found along the eastern coast of North America from the Gulf of St. Lawrence to Texas. Historically, Native Americans used the quahog as a component in wampum, the shell beads exchanged in the North American fur trade. Larvae Adult clams have many natural predators including marine birds, rays, and crabs. Its primary function is to Despite a number of small scale surveys of clam stocks in the Bay there has been only one recent effort fo- Habitat Discussion: Hard clams naturally occur along the eastern coast of North America from the Gulf of Saint Lawrence, Canada to the northern part of the Gulf of Mexico (Kraeuter 2004). Clams burrow into the sediment, leaving only their siphons expose to feed. The shell's interior is usually white with dark purple patches. on the gills is moved anteriorly to the clam's "mouth" by ciliary action. Quahog parasite X (or quahog parasite unknown [QPX]) disease of the hard clam Mercenaria mercenaria is caused by a poorly known protistan parasite. However, 44% of sand habitats and 54% of shell habitats were unoccupied suggesting that even habitat types that typically support higher clam densities may currently be underused. Habitat restoration is a critical step for conserving these valuable habitats, but new approaches are needed to increase restoration success and ensure their survival. Clams are bivalves, a group of mollusks with a shell consisting of two roughly equal-size valves that are hinged They are sold They also occur Maine’s hard clam was assigned to the quahog common name, and Massachusetts and New Hampshire’s surf clam were assigned to Atlantic surf clam. of clams per person per day is legal. A hard clam also possesses a hatchet-shaped foot that it uses [11][12] The toxin affects the human central nervous system. There have been records in the fields in Chiba, Tokyo, Toyama, Wakayama, Okayama, Kagawa, Kumamoto, and Kagoshima Prefs. Great South Bay Hard Clam Restoration Working Group Final Report, 2011; Factors Controlling Mercenaria mercenaria (hard clam) Populations in South Shore Bays of Long Island, NY. In South Carolina, the spawning season Giant clams are sedentary animals that are found in the relatively shallow water not more than 20 meters deep. The hard clam has two non-shelled larval stages: a trochophore and an early veliger. 2,3 Water clarity affects light transmission at depth, which is an important determinant for where seagrass, an essential fish habitat, can grow. Clams from such waters are transplanted to clean bay waters or processed in a state-approved depuration plant for purification. Eversole, A. G. 1987. Hard clams prefer saline water and cannot survive if the salt content is too low. Hard-shell clams can live over 40 years. at one end. 1000 Assembly Street, Columbia, SC 29201 Above that are the cherrystones, and the largest are called quahogs or chowder clams.[2]. Invasion information: Range in Japan: No known evidence for establishment in Japan. Venerids make up a significant proportion of the world fishery of edible bivalves. In Chesapeake Bay the hard clam is restricted to salinities above approximately 12 ppt. Clam culture in the U.S. began in the early 1920s. Historical populations of native hard clams within SW Florida estuaries were legendary, referred to as "the largest bed of hard clams in the United States". The hard clam's thick, rounded shells vary in color from brownish to gray or whitish and can grow to 4 inches or longer. 2005 COASTAL HABITAT PROTECTION PLAN CHAPTER 3. Hard clam. Hard clam density in Chesapeake Bay is positively associated with increasing sediment grain size; 78% of all clams collected were found in shell or sand habitats. A population of hard clams exists in Southampton Water in Hampshire, England. These concentric bands are conspicuous and are closely spaced around the margins but more widely spaced around the umbo. By G.Curtis Roegner and Roger L. Mann. Because the clams cannot be harvested until they reach a legal size of 1-1/2 inch, they have been able to spawn at lease once. However, 44% of sand habitats and 54% of shell habitats were unoccupied suggesting that even habitat types that … Dosinia laminata Tivela species, for example, have the triangular outline of the surf clams in other bivalve families, and occur often in surf zones. For other uses, see. Due to the significance of this resource, a hard clam density study of the Indian River Bay and Rehoboth Bay was conducted in 2010 and 2011 (hereby referred to as the ‘2011 survey’) to identify significant changes in clam populations since previous surveys in the late 1970’s and to identify areas of productive clam habitat. The shell protects the more vulnerable smaller clams from predators. Species profiles: life histories and environmental requirements of coastal fishes and South Carolina South Carolina Department of Natural Resources - Rembert C. Dennis Building The siphon which takes in water is called ( Schroeder 1924) . Hard clams have two short siphons through which water is filtered. While little is known about the disease, research is currently under way in several laboratories. The term "red tide" refers to an accumulation of a toxin, such as saxitoxin, produced by marine algae. These long-lived, dense-shelled bivalves live in sandy or muddy bottoms throughout Florida waters. Confusingly, the "ocean quahog" is a different species, Arctica islandica, which, although superficially similar in shape, is in a different family of bivalves: it is rounder than the hard clam, usually has black periostracum, and there is no pallial sinus in the interior of the shell. Oysters and clams. Spawning is induced by rising Two species of hard clams occur along the Atlantic and Gulf of Mexico coasts of North America: the southern hard clam, Mercenaria campechiensis Gmelin 1791, and the northern hard clam, ~lercenaria mercenaria Linne 1758 (Wells 1957b). Hard clams are quite common throughout New England, north into Canada, and all down the Eastern seaboard of the United States to Florida; but they are particularly abundant between Cape Cod and New Jersey, where seeding and harvesting them is an important commercial form of aquaculture. invertebrates (South Atlantic): hard clam. Because spawning activity is closely Infected clams are characterized by the presence of blisters or pustules in the mantle and later by gaping and death.[8]. Algae is a producer that needs no seed to sprout. For example, if a map from 1983 shows the area in question as having a “moderate density” of hard clams, while a newer map shows “low density”, the property is still considered shellfish habitat and subject to the shellfish habitat rules as such. For example, if a map from 1983 shows the area in question as having a “moderate density” of hard clams, while a newer map shows “low density”, the property is still considered shellfish habitat and subject to the shellfish habitat rules as such. However, 44% of sand habitats and 54% of shell habitats were unoccupied suggesting that even habitat types that typically support higher clam densities may currently be underused. This combination greatly reduces the potential locations available for expansion. The exterior of the shell, except nearest the … While hard clams (Mercenaria spp.) the incurrent, or inhalant siphon, and it lies on the ventral side (underside) of the clam. Each female can produce between 1 and 5 million eggs during a spawning event. They range in size from 1 to 4 inches wide, and vary in color from white to gray with dark rings. External shell color is off-white or pale yellowish-brown, while the inside is white or pale yellow with purple related to water temperature, times of spawning vary greatly with latitude. 1995. The hard clam has many alternative common names. 1 (such as brown tide blooms) and possible increased predation by blue crabs 2. and other predators such as cownose rays. This natural distribution is evidence of the adaptability of this species to a broad range of water temperatures, both as larvae and adults. The hard clam, commonly called a quahog, is a bivalve (two shells) mollusc that lives in bays and estuaries along the Atlantic Ocean and Gulf of Mexico. The Service is proposing to designate critical habitat for the Suwannee moccasinshell under the Endangered Species Act (ESA). Hard clam density in Chesapeake Bay is positively associated with increasing sediment grain size; 78% of all clams collected were found in shell or sand habitats. The hard clam, Mercenaria mercenaria, is found along the eastern coast of North America from the Gulf of St. Lawrence to Texas. to move around and bury itself in the mud. Rhode Island is situated right in the middle of "quahog country" and has supplied a quarter of the U.S.'s total annual commercial quahog catch. Species Description. Two species of hard clam are found in Florida: the northern quahog (Mercenaria mercenaria) and the southern quahog (Mercenaria campechiensis).Historically, clams … The abundances and distribution patterns of hard clams in Chesapeake Bay are While conservation and protection of existing hard clam habitat is the best strategy for addressing this problem, restoring areas that supported hard clams in the past is a valuable management measure. SW Florida’s seemingly inexhaustible wild clam beds supported 2 canneries for 40+ years. Hard clam aquaculture Hard clams are the most com-monly cultured of the bivalve species. Although hard clams produce large numbers of eggs, mortality of pre-adult stages is extremely high. Harte, M. E. 2001. The hard clam has a life history that is similar to that of the American oyster (Eversole 1987). Once a young clam larvae finds a suitable location on the reef it attaches itself to the reef and stay there for the rest of its life. Abstract. Species Habitat. However, only one-half bushel Micheli 1997, Nakaoka 2000), and additional clam populations must What actions are being taken by the U.S. Concentric growth rings are usually visible between the margin of each valve and the hinge swelling, or Hard clam minimum size limit is 1” in the transverse dimension and only hand-held harvesting devices are allowed in the Coastal Bays. SHELL BOTTOM 3.1. Mercenaria mercenaria has a large, heavy shell that ranges from being a pale brownish color to shades of gray and white. Successful ... softshell and hard clam resources in order to illustrate the relation of these resources to streams and shoreline areas vital to their conservation. It is also known as the Northern quahog, round clam, or chowder clam. Color: Shell color ranges from white to grey, with dark rings. individuals burrowing deeper than large ones. size and condition. In Chesapeake Bay the hard clam is restricted to salinities above approximately 12 ppt. This species is enjoyed in a variety of culinary ways, such as chowders, clam bakes, and on the half shell. DESCRIPTION AND DISTRIBUTION Definition For the purposes of this plan, shell bottom is defined as “estuarine intertidal or subtidal bottom composed of surface shell concentrations of living or dead oysters (Crassostrea virginica), hard clams (Merceneria Size: 1 to 4 inches wide. Clams, like oysters, are filter feeders, passing water across the gills where food particles are removed. two years of age. Clams are also Adults are sessile – they stay in one place – and inhabit both intertidal and sub-tidal areas. Coloration of the siphons varies from cream Females release eggs through the exhalent siphon, and fertilization by nearby males occurs freely Fish and Wildlife Service? WWWWWWW WWWWWWW Shellfish and Snail Identification and Recreational Limits. Similar to other bivalves, clams have a fleshy tissue membrane, called the mantle, covering 1 cup evaporated milk. settlement of clam larvae, resulting in dense patches of clams. and factoring in the recreational harvest, the hard clam contributes about $20 to 40 million to New Jersey’s economy each year. People aren't the only species that eats hard-shell clams. Summary of soft-shell clam data from previous research and the present study. New Hampshire’s data only listed oyster for these features, after contacting the data source it was determined that the species of these features were Eastern oysters, these were updated in this layer. However, hard clam is constantly released for culture fishery and possibly some times escape. In coastal areas of New England, New York, and New Jersey, restaurants known as raw bars or clam bars specialize in serving littlenecks and topnecks raw on an opened half-shell, usually with a cocktail sauce with horseradish, and often with lemon. Giant Clam - Habitat Where Do Giant Clams Live? For example, a soil delineation with the name “Rhodesfolly fine sand, 0 to 1 meter water depth” may also include small, unmappable areas of Quahogs, or hard-shell clams, are shellfish that inhabit the mud flats along the eastern seaboard from Canada to Florida. Current Management Measures . and chowders, the largest, are least expensive and typically marketed to make clam chowder. The species has also been introduced and is farmed on the Pacific coast of North America and in Great Britain and continental Europe. The latter species, also commonly kno\'m as the quahog, was formerly named Venus mercenaria. Although QPX disease was first recorded on the Atlantic coast of Canada in the early 1960s, it did not become a major economic problem until its appearance in cultured clams at Prince Edward Island, Massachusetts in 1992, and Virginia in 1997. the excurrent, or exhalent siphon, which is located dorsally (back side). Small tidal creeks that are partly closed by oyster beds at the mouth appear to be one of the more productive habitats for this species. However, pr edation rates on hard clams can var y dra- matically within localized habitats (e.g. Biological Report 82(11.75). Other Authors: will closely resemble a natural condition in terms of structure and function (Bagget et al., 2014). Saved in: Main Author: Mulholland, Rosemarie. Clam chowder may have been the first American soup. During the first phase of sexual maturity the clam functions as a male. Water is expelled through The Service is proposing three actions: Protecting the Atlantic pigtoe, a freshwater mussel native to rivers of the Atlantic seaboard, as threatened under the Endangered Species Act (ESA). [11] Eating contaminated shellfish, raw or cooked, can be fatal. Hard clams are quite common throughout New England, north into Canada, and all down the Eastern seaboard of the United States to Florida; but they are particularly abundant between Cape Cod and New Jersey, where seeding and harvesting them is an important commercial form of aquaculture. FARMING: Although hard clams grow wild off Georgia’s coast, it’s more efficient to “plant” seed, or baby clams, on leased land, so farmers know exactly where to look for mature clams when it’s time to harvest. The hard clam (Mercenaria mercenaria), also known as a quahog (/ˈk(w)oʊhɒɡ/; or quahaug), round clam or hard-shell (or hard-shelled) clam, is an edible marine bivalve mollusk that is native to the eastern shores of North America and Central America from Prince Edward Island to the Yucatán Peninsula. Habitat: Tidal flat of inner bay. We can see algae when we do not clean the fish tanks. Algae is green and moldy. do not create vertical “reefs,” they often occur in aggregations of adequate density to provide habitat for other species (Langton and Robinson 1990; Stokesbury 2002). Restoration is the process of establishing or reestablishing a habitat that eventually . A model for predicting the distribution of the habitat of the Japanese hard clam Meretrix lamarckii has been developed, taking the life history of the clam between larva and adult Seasonal appearance: All year. It was discovered along the coast of Cape Cod, Massachusetts in 1995. Hard clams inhabit coastal waters over a very wide geographic range, from Canada to Florida. Unfortunately, New Jersey’s natural clam beds have diminished steadily for the past thirty years. Hard clam beds Dense aggregations of the hard clam (Mercenaria mercenaria), typically in subtidal areas of bays and estuaries to approximately 15 meters in depth and generally amid fine sediment or shell fragments. To determine the indirect effects of biotic structure on prey populations, we assessed predation on patches of hard clams (Mercenaria mercenaria) by large odor-mediated blue crab (Callinectes sapidus) and knobbed whelk (Busycon carica) predators at 0, 5, and 10 m from oyster reefs in intertidal salt marshes.