8/30/2023 0 Comments Underwater shelfScientists also want to understand the potential impacts on the sanctuary benthos from cable-laying. Currently, there is an incomplete picture about the extent of trawling’s impacts, but the use of trawl gear is an ongoing source of concern. Conservation and Management IssuesĬonservation and management issues affecting shelf resources in the northern California sanctuaries include seabed disturbance, non-sustainable fishing, cable-laying and radioactive waste.īottom trawling, which relates to the first two of these issues, can have negative impacts on benthic habitats. This abundance of benthic life attracts pelagic predators, including seabirds and marine mammals. Areas of variable relief and rocky substrate on the shelf are often associated with high species diversity. The complex physical structure created by rocky, hard-bottom areas provides habitats for a very different suite of organisms these include rockfishes, deep-water corals, sponges and anemones. Mushroom soft coral formerly called Anthomastus ritteri observed at 320 m. Species that thrive in this environment include clams, sea pens, Dungeness crabs and flatfishes such as California halibut and English sole. These animals have adapted to the continuous shifting of sediments by ocean currents. Many species, from fishes to invertebrates, live on the surface of, or buried in, the soft sediments. The marine life along the continental shelf varies with the different habitats. The continental shelf is desginated in green and includes depths between 30 and 200 meters. In the Greater Farallones, the continental shelf encompasses several notable features: large underwater sand dunes between the Farallon Islands and Point Reyes as well as a long rocky ridge that includes Hurst Shoal, Farallon Islands, Fanny Shoals, Rittenberg Bank and Noonday Rock.īasic depth zones within and near MBNMS are shown in the interactive map below, along with Sanctuary and California MPA boundaries. Throughout the three northern California sanctuaries, the habitats along the shelf vary greatly, from soft-bottom (sand, mud, silt and/or clay) to rocky (coarse gravel to boulders, caves, pinnacles and/or outcrops). the intertidal (salt spray to extreme low water).It can be subdivided according to depth, including: Beyond the break (at a depth of approximately 200 meters, or 650 feet), the slope descends more steeply to the ocean floor. The continental shelf is the gently dipping submerged margin of the continent that extends from the nearshore to the shelf break.
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