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Freshwater Mussels:
Engineering Ecosystems One Shell at a Time

(Released August 2011)

  by Natalie Abram  


Key Citations





Abalone: A large mollusk of the genus Haliotis, having a bowlike shell bearing a row of respiratory holes, the flesh of which is used for food.

Abiotic: Nonliving.

Anterior: Situated at the front or top.

Benthos: The biogeographic region that includes the bottom of a lake, sea, or ocean, and the littoral and supralittoral zones of the shore.

Bioindicator: A biological indicator of the well-being or abundance of an organism, which is then used to describe the quality of the ecosystem.

Biota: Living organisms.

Bivalve: A synonym of mussel.

Bivalvia: The class, subdivision of phylum Mollusca, named because of two shells.

Brackish: Containing a mixture of seawater and fresh water. Brackish water is somewhat salty.

Byssal thread: Strong, silky fibers made from proteins that are used by marine mussels to attach to rocks, pilings, or other substrates.

Calcium Carbonate: A white crystalline salt occurring in limestone, chalk, marble, calcite, coral, and pearl: used in the production of lime and cement. Formula: CaCO 3.

Carbon cycling: The continuous process by which carbon is exchanged between organisms and the environment. Carbon dioxide is absorbed from the atmosphere by plants and algae andconverted to carbohydrates by photosynthesis. Carbon is then passed into the food chain and returned to the atmosphere by the respiration and decay of animals, plants, and other organisms.

Cellular Respiration: The process of cell catabolism in which cells turn food into usable energy in the form of ATP. In this process glucose is broken down in the presence of molecular oxygen into six molecules of carbon dioxide, and much of the energy released is preserved by turning ADP and free phosphate into ATP.

Cockle: Any bivalve mollusk of the genus Cardium, having somewhat heart-shaped, radially ribbed valves.

Conch: Any of various tropical marine gastropod molluscs of the genus Strombus and related genera, esp S. gigas (giant conch), characterized by a large brightly colored spiral shell.

Conchologist: One who studies and collects mollusc shells.

Conglutinate: United by a glutinous substance.

Corbicula: Corbicula fluminea is an exotic mollusc from Asia.

Crystalline: A homogenous solid formed by a repeating, three-dimensional pattern of atoms, ions, or molecules and having smooth external surfaces with characteristic angles between them. Crystals can occur in many sizes and shapes.

Detritus: Matter produced by the decay or disintegration of an organic substance.

Diatom: Any of various microscopic protists of the phylum Bacillariophyta that live in both fresh and marine water, have hard bivalve shells (called frustules) composed mostly of silica, and often live in colonies. Most diatoms can perform photosynthesis. They make up a large portion of the marine plankton and are an important food source for many aquatic animals.

Dreissena: Dreissena polymorpha, also known as a zebra mussel; a one-inch-long mollusk imported accidentally from Europe; clogs utility inlet pipes and feeds on edible freshwater mussels.

Ecto-parasite: A parasite that lives on the exterior of its host.

Estuarine: (brackish water) When that part of the mouth or lower course of a river in which the river's current meets the sea's tide.

Eutrophication: The process by which a lake, pond, or stream becomes eutrophic, typically as a result of mineral and organic runoff from the surrounding land. The increased growth of plants and algae that accompanies eutrophication depletes the dissolved oxygen content of the water and often causes a die-off of other organisms.

Exotic Species: Non-native plants or animals that have been introduced into areas where they do not naturally occur, mostly by human actions.

Filter-feeding: Pertaining to an aquatic animal, such as a clam or sponge, that feeds by filtering tiny organisms or fine particles of organic material from currents of water that pass through it.

Fouling: Refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consists of either living organisms ( biofouling) or be a non-living substance (inorganic or organic).

Freshwater: Consisting of or living in water that is not saline.

Gametes: Mature sexual reproductive cells, as sperms or eggs.

Ganglion: A compact group of neurons enclosed by connective tissue and having a specific function. In invertebrate animals, pairs of ganglia occur at intervals along the axis of the body, with the forward most pair functioning like a brain.

Geomorphology: The scientific study of the formation, alteration, and configuration of landforms and their relationship with underlying structures.

Gill: The organ that enables most aquatic animals to take dissolved oxygen from the water. It consists of a series of membranes that have many small blood vessels. Oxygen passes into the bloodstream and carbon dioxide passes out of it as water flows across the membranes.

Glochidium: The larva of a freshwater mussel of the family Unionidae that lives as a temporary parasite in the gills or on other external parts of fishes (pl. glochidia).

Gravid: Carrying eggs or developing young.

Green Algae: Freshwater algae of the phylum Chlorophyta, often growing on wet rocks, damp wood, or on the surface of stagnant water.

Hemoglobin: An iron-containing respiratory pigment of vertebrate red blood cells that functions primarily in the transport of oxygen.

Hemolymph: Present in invertebrates and consists of water, amino acids, inorganic salts, lipids, and sugars.

Heterodonta: A subclass of marine mussels with two rows of hinge teeth.

Homeostasis: The tendency of an organism or cell to regulate its internal conditions, such as the chemical composition of its body fluids, so as to maintain health and functioning, regardless of outside conditions.

Hydrology: The scientific study of the properties, distribution, and effects of water as a liquid, solid, or gas on the Earth's surface.

Impoundment: A body of water confined within an enclosure, as a reservoir.

Invasive: Not native to and tending to spread widely in a habitat or environment. Invasive species often have few natural predators.

Ligament: Any one of the bands or sheets of tough fibrous connective tissue.

Mantle: The layer of soft tissue that covers the body of a clam, oyster, or other mollusk and secretes the material that forms the shell.

Marine: Relating to a system of open-ocean and unprotected coastal habitats, characterized by exposure to wave action, tidal fluctuation, and ocean currents and by the absence of trees, shrubs, or emergent vegetation. Water in the marine system is at or near the full salinity of seawater.

Mollusk (mollusc): Any invertebrate of the phylum Mollusca, typically having a calcareous shell of one, two, or more pieces that wholly or partly enclose the soft, unsegmented body, including the chitons, snails, bivalves, squids, and octopuses.

Malacologist: One who studies the branch of zoology concerned with the study of mollusks.

Nacre: A hard, iridescent substance that forms the inner layer of certain mollusk shells, used for making buttons, beads, etc.

Nerve Cord: A solid double strand of nerve fibers along the length of the body in elongate invertebrates connecting with a pair of nerve ganglia at each body segment.

Non-Point Source Pollution: Pollution that comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters.

Open-Circulatory System: Open circulatory systems (evolved in invertebrates) pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells.

Organic: Class of chemical compounds that formerly comprised only those existing in or derived from plants or animals, but that now includes all other compounds of carbon..

Osmoregulation: The maintenance of an optimal constant osmotic pressure in the body of a living organism.

Paleoheterodonta: Freshwater subclass that has a single row of hinge teeth.

pH: A numerical measure of the acidity or alkalinity of a solution, usually measured on a scale of 0 to 14. Neutral solutions (such as pure water) have a pH of 7, acidic solutions have a pH lower than 7, and alkaline solutions have a pH higher than 7.

Phylum: A subdivision of a taxonomic kingdom grouping together all classes of organisms that have the same body plan.

Phytoplankton: Plankton consisting of free-floating algae, protists, and cyanobacteria. Phytoplankton form the beginning of the food chain for aquatic animals and fix large amounts of carbon.

Planktivores: Organisms that consumes suspended microscopic particles from the water column.

Point Source Pollution: Contamination that enters the environment through any discernible, confined, and discrete conveyance, such as a smokestack, pipe, ditch, tunnel, or conduit.

Posterior: Situated behind or at the rear.

Rotifer: Any of various tiny, multicellular aquatic animals of the phylum Rotifera, having a wheel-like ring of cilia at their front ends.

Respiration: The act or process by which an organism without lungs, such as a fish or plant, exchanges gases with its environment.

Scallop: Any of the bivalve mollusks of the genus Argopecten ( Pecten ) and related genera that swim by rapidly clapping the fluted shell valves together.

Substrate: The surface on or in which plants, algae, or certain animals, such as barnacles or clams, live or grow. A substrate may serve as a source of food for an organism or simply provide support.

Taxonomy: Study of naming, identifying and classifying organisms. Uses the following classification titles (in order of most broad to most specific) Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Trophic Levels: Any of the sequential stages in a food chain, occupied by producers at the bottom and in turn by primary, secondary, and tertiary consumers. Decomposers (detritivores) are sometimes considered to occupy their own trophic level.

Unionid: A nickname for Order Unionidae.

Valve: Any of the separable pieces that make up the shell of a mollusc.

Veliger: Larva typical of certain mollusks such as marine snails and bivalves. The veliger develops from trochophore (q.v.) larva and has large, ciliated lobes (velum) that form from the ciliary ring (prototroch) characteristic of the trochophore stage. The velum, used in swimming and feeding, generally disappears in the adult. During the veliger stage, the mollusk begins to develop a foot and shell.

Water Column: A conceptual column of water from surface to bottom sediment.

Zooplankton: Plankton that consists of tiny animals, such as rotifers, copepods, and krill, and of microorganisms once classified as animals, such as dinoflagellates and other protozoans.