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Marine Life in the Harbor

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Marine Life in the Harbor Despite Baltimore's polluted water, over 18 different species of aquatic life have been identified living in the Inner Harbor. Pollutants such as arsenic, mercury, lead, benzene and DDT enter the water through industrial processes and urban run off. These toxins accumulate in sediment and over time make their way into the tissues of fish and crabs through water, food, and air intake, making them unsafe for human consumption. On some occasions, fish will develop bloody lesions caused by protozoans that are made toxic by excess nutrient enrichment. At times, lack of dissolved oxygen, changes in salinity and temperature, and sewage spills can cause massive fish kills, destroying thousands of Harbor fish. It is surprising that these fish, crabs, and invertebrates still survive in water of such poor quality. The following is a list of animals that have been seen living in the Harbor as recently as this year. Mummichog Essential for scientific research, the mummichog is an indicator species in severely polluted systems and can survive at very low oxygen levels. In the Harbor we've found these fish in large schools, looking for plant matter, crustaceans, and small mollusks and fish to feed on. The male mummichogs are distinguished by their more intense color and stripes, while the females are paler. The mummichog serves our harbor by being a critical member of the food chain, as well as aiding valuable research on the conditions of the water. White Perch A relative of the striped bass, a widely popular catch, the white perch is silvery with faint lines, a forked tail, and a protruding jaw. Since they are a forage species, the Harbor, with its crabs and small fish, make it the perfect feeding ground for these ravenous predators. Despite poor water quality, white perch can live as long as 17 years, adapting to different salinity and dissolved oxygen levels. Atlantic Menhaden The Atlantic Menhaden are filter feeders, meaning they swim with their mouths open and strain water through their gills to filter out plankton. They are inedible to humans but an important part of the food chain for predators in and around the Harbor. The Atlantic Menhaden is a type of herring and is distinguished by a dark shoulder spot, a deeply forked tail fin, and a projecting lower jaw. Blue Crab Despite its red hue when cooked, the blue crab has bright blue claws with red tips, swimming and walking legs, and a shell that is twice as wide as it is long. During warm weather, crabs populate shallow-water areas like the Harbor and move to deeper areas in winter. Blue crabs are so successful because they are omnivores that feed on nearly anything, including clams, oysters, crustaceans, dead fish, bristle worms, detritus, and juvenile blue crabs. The Harbor blue crabs are easily visible from the waterfront, but inedible because of elevated toxin levels. Atlantic Sea Nettle The Atlantic sea nettle has a smooth, milky white bell and up to 24 stinging tentacles. Their tentacles are used to entangle, paralyze, and capture their prey, which includes fish, shrimp, comb jellies, and other small creatures. The jellyfish that are found in the Harbor are almost 90 percent water, but fish and invertebrates still feed on them. Sea nettles develop important relationships with a diverse group of species in the Harbor. Atlantic Silverside The Atlantic Silverside is a small, schooling fish with a distinct silver band on the side. Silversides are very common subjects for scientific research because of their sensitivity to extreme environmental conditions such as low oxygen levels, temperature changes, and contaminants. Silversides eat small crustaceans, algae, worms, shrimp, zooplankton, and insects found in the water, while providing striped bass, blue fish, mackerel and shore birds with an abundant food source. Pumpkinseed Sunfish The pumpkinseed sunfish is known for its mottled orange, blue, and green body and its willingness to bite. The Harbor’s recent low salinity levels may benefit the typically freshwater fish more than other species. Pumpkinseeds feed on snails, worms, insects, mollusks, small fish, and vegetation. The pumpkinseed sunfish could be a popular and attractive catch if the water conditions in the Harbor improve. Comb Jelly The comb jellies do not have stinging tentacles and are marked with bright, iridescent bands of color. The main species of comb jelly found in the Baltimore area is the sea walnut. Comb jellies are better swimmers than sea nettles, using their combs to push themselves forward and feed on planktonic organism and small fish. Barnacle With its shallow waters, rocky bottoms, and substantial boat population, barnacles flourish in the Harbor. Barnacles have a top opening with two valves that open and close for feeding. Feathery appendages sweep tiny particles of plankton and detritus into the opening. Their larvae are also a critical food source for young fish. Few larvae settle and develop shell plates as adults because of the water conditions and fish predators. Mussel The Atlantic ribbed mussel is found in the Harbor attached to surfaces by thread-like glands, or buried in mud. It is a bivalve mollusk with glossy, ribbed shells varying in color from olive to black. The ribbed mussel is a filter feeder, drawing water into its mouth, filtering out algae and plankton during high tide. At low tide, the mussel closes its shell to keep in waste products that are toxic to humans. Sea Slug Sea slugs are soft-bodied, shell-less mollusks with oral tentacles on the head, sensory tentacles on the back, and various gills and growths on the top of the body. Eight slug species are found in the Bay, dividing into two types, either feeding on algae and other plants, or on animals, such as jellyfish polyps or hydroids. Both types are found around pilings, buoys, hydroids, and grassy bottoms. Lacking a defensive shell, sea slugs rely on bright coloration and strong scent to avoid being preyed upon. Anemone This whitish relative of the sea nettle is found on rocks, pilings, and other surfaces in shallow water. The anemone has a circle of 40 to 60 petal-like tentacles growing from the top of a rounded stalk. In the center of the tentacles is a tiny mouth, which feeds on plankton and tiny fish captured by the tentacles. The anemone moves just like an inchworm, remaining attached to a surface but moving several inches in a few hours. Spot One of the most abundant species in the Chesapeake Bay is the spot fish, also known as the “Norfolk spot.” Spot are unique in that it is a member of the drum family, able to make a loud drumming sound by using special muscles to vibrate its swim bladder. Spot are recognized by the large black spot near the gill opening and grow to about 11 or 12 inches long. Spot are bottom-feeders, preying on bristle worms, mollusks, crustaceans, and plant and animal detritus. Sharks, bluefish, weakfish, striped bass, and summer flounder prey upon spot as well. Whip Mud Worm More than 110 species of bristle worms have been identified in the Bay. The whip mud worm is a bristle worm that builds burrows in which it lives. The mud worm uses its two tentacles to snare food floating by and transport it along cilia to the mouth, similar to a conveyor belt. Whip mud worms feed on bits of organic matter and plankton. Bryozoans Only visible under a microscope, bryozoans are aquatic organisms living in colonies of interconnected individuals. There are 125 known species, but the most abundant in the Harbor is the Gymnolaemata group. They are filter feeders that sieve food particles out of the water using a retractable lophophore, a “crown” of tentacles lined with cilia. Predators of marine bryozoans are sea slugs, fish, sea urchins, crustaceans, and mites. .
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