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bullet Bridge DATA Series: National Marine Sanctuaries Fish Answer Page

General Questions

  1. Who Lives Where?

    Belted Sandfish - Gray's Reef; often found in silty waters.

    Blue Angelfish - Gray's Reef, Stetson Banks; found around rocky or coral reefs, feeds primarily on sponges.-------Note: Both Flower Garden Banks and the Florida Keys have this and other angelfishes, some of which are seen greater than 50% of the time, and some of which are not. If you chose to list the blue angelfish under all sanctuaries, your reasoning would not be wrong; however, the high sighting frequencies of this particular species at Gray's Reef and Stetson Banks illustrates two points: (1) the unusual mix of tropical and temperate species at Gray's Reef; and (2) the abundant food supply (sponges) at Stetson Banks.

    French Grunt - Florida Keys; juveniles abundant in nearshore seagrass beds.

    Queen Parrotfish - Flower Garden Banks; feeds on algae scraped from rocks.-------Note: If you also chose to list the parrotfish under Florida Keys and Stetson Banks, your reasoning would be correct. However Flower Garden Banks is noted for its more than 80 forms of algae. The Florida Keys has three species of parrotfish that are sighted greater than 50% of the time, and Stetson Banks has one. At Flower Garden Banks, there are four.

    Yellowtail Snapper - Florida Keys; most commonly found off south Florida, young individuals usually found over weed beds.

    Black Sea Bass - Gray's Reef; found in temperate waters from Maine to NE Florida and the eastern Gulf of Mexico, likes rock jetties and rocky bottoms.

    Spanish Hogfish - Florida Keys, Flower Garden Banks, and Stetson Banks; found from Bermuda to south Florida and throughout the Gulf, inhabits rocky or coral reefs, feeds on brittle stars, crustaceans, mollusks, and sea urchins.

    Neon Goby - Florida Keys, Flower Garden Banks, and Stetson Banks; found from southern Florida to Texas, inhabits coral heads.

    Seaweed Blenny - Stetson Banks; inhabits eroded basins and limestone boulders covered by an algal mat, sea fans, etc. Eroded basins are plentiful at Stetson Banks; however, the limestone boulders and sea fans might have led you to list it under Gray's Reef also. It is found there, but it is less common.

  2. Who Lives Everywhere?

    It is the Great Barracuda, and adults occur in a wide range of habitats from murky inner harbors to open seas. Great barracuda occur in most tropical and subtropical nearshore habitats throughout the world's oceans. An interesting exception is in the eastern Pacific Ocean where the great barracuda has apparently never ranged. This limit to their distribution may be because of the large open expanse of ocean between this area and the Hawaiian Islands. Barracuda have a large gape and can feed on large fish by chopping them in half with their jaws. Their prey includes mullet, snapper, herring, sardines, grunts, jacks, mackerel and cephalopods.

  3. Species Diversity

    Tropical marine environments in general support greater diversity than temperate waters because marine life in general is favored by warm temperatures rather than cold. This relates to the physiology of animals and plants. Coral reefs support more species per unit area than any other marine ecosystem. Although you will find that in open tropical waters nutrient availability is generally low, limiting primary production, reefs create physical dynamics that "trap" or concentrate available nutrients at relatively shallow depths to ensure increased primary production. Greater primary production translates to a greater food supply to support organisms. The organisms that live on and around reefs are specially adapted to efficiently and rapidly exploit nutrients and food as they become available. They occupy ecological niches which avoid competition for limited resources.

    Among these 3 sanctuaries, the Florida Keys has the greatest species diversity, with 378 total species. There is a wide variety of habitat types there to support a greater diversity of organisms. One type of habitat which specifically contributes to a greater variety of organisms are seagrass beds, and this habitat type is not found at the other two sanctuaries. In addition, the overall size of the Florida Keys National Marine Sanctuary is many times greater than Flower Garden Banks, Stetson Banks, or Gray's Reef.

    Flower Garden Banks and Stetson Banks fall in the middle, with 225 and 204 total species, respectively. Although Flower Garden Banks is a tropical reef environment, it is extremely isolated, and therefore has a small local gene pool. This is because most tropical marine species like fish and corals have a planktonic larval stage, and there are many organsims that cannot travel more than a few days as larvae. It is estimated that it takes a minimum of 9 days for a larvae that leaves the Yucatan Peninsula (the closest coral reef) to reach the Flower Garden Banks, so many organisms do not survive the trip. The Flower Garden Banks are also on the edge of coral reef distribution, so the physical characteristics are not quite as constant and predictable as in the Florida Keys, and they are at a greater mean depth with limited light intensities.

    Gray's Reef has the lowest species diversity, with 89 total species. Its temperate characteristics, depth and its relative isolation are contributing factors. Only the heartiest of tropical species can live there year-round.

    It should also be noted that the Florida Keys reef system is much better studied than the other two reef systems, and this greater research effort may contribute to the number of species discovered thus far.

  4. What are some potential threats to marine fish diversity?

    Overharvesting, habitat destruction, and pollution are all threats to marine fish diversity.

  5. What role do the National Marine Sanctuaries play in protecting/maintaining species diversity?

    Each sanctuary is responsible for the protection of its habitats, research and monitoring, promoting compatible uses, education, and enforcing regulations. For additional classroom activities for all grade levels on the Florida Keys National Marine Sanctuary, go to the National Geographic Society's Classroom Ideas page.

 The Bridge is sponsored by NOAA Sea Grant and the National Marine Educators Association

Virginia Sea Grant Marine Advisory Program
Virginia Institute of Marine Science
College of William and Mary