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Underwater Habitats of the MBNMS

Encompassing more than 5,300 square miles, the Monterey Bay National Marine Sanctuary is one of the richest, most diverse marine environments in the world encompassing wave-swept beaches, lush kelp forests, and one of the deepest underwater canyons in North America. These habitats abound with life, from tiny plankton to playful sea otters, to the largest animal that has ever live on earth -- the blue whale. Here is a brief look at some of the more common and accessible habitats you may see underwater.

picture of kelp in MBNMS Kelp Forests

Kelp is what makes diving in the Sanctuary and along the California coast so special. The familiar giant kelp is one of nearly 20 varieties of kelp found in the Sanctuary. In ideal conditions this remarkable plant can grow up to 18 inches per day, and in stark contrast to the colorful and slow-growing corals, the giant kelp canopies tower above the ocean floor. Kelp is the backbone of Monterey Bay coastal ecology. Like the trees in a forest these giant algae provide food and shelter for the many organisms dependent on these plants. Also like a terrestrial forest, kelp forests experience seasonal changes. Storms and large weather events, like the El Nino, can tear and dislodgethe kelp, leaving a tattered winter forest to begin its growth again each spring.

On the rocks where the holdfasts secure kelp fronds to the bottom live many invertebrates including abalone, sea urchins and sea stars. Among the kelp blades live a variety of fish - particularly juveniles. You will most likely see rockfish and senoritas amongst the blades, and if you look closely you might catch a glimpse of cleverly camouflaged turban snails, kelp crabs and kelpfish, a unique creature that can change its color to suit its environment. The canopies host a number of sea birds and are considered "home" to the sea otter. It is there, often wrapped in kelp that the otter lounge, play and groom themselves.


picture of rock w/ reef in MBNMS

Rocky Shores and Reefs

Much of the spectacular diversity can be found nestled amongst the rock where the Sanctuary meets the shore. From the intertidal zone to the sea floor, an abundance of sea stars, anemones and kelp can be found. These rocky habitats are both beautiful and fragile. The subtidal reefs host a myriad of sponges, anemones and corals, whose presence converts the dark rock to fields of vibrant color. Holes left by burrowing clams, piddocks and constant weathering become shelter for the many reef animals including agile octopi, sedentary sea cucumbers, and colorful nudibranchs. Many species of fish can be seen around rocky outcroppings.


picture of perch in MBNMS

Sandy Beaches

The sandy beach and sea floor comprise the most extensive habitats in the Sanctuary. At first glance the sand seems barren and unproductive. After a while, if you are careful not to kick up sand, you might see tiny benthic communities of tube-building worms come alive as they sweep the passing nutrient rich waters with tentacles to capture food. Sand dabs and stingrays sail along the silty bottoms feeding or lie in wait on the sandy floor, blending in perfectly. If you are really lucky you may encounter a cluster of living sand dollars, half buried in the sand. You are almost certain to see an occasional bat star or decorator crab making its way across the sandy floor, scavenging for any debris it might find.


picture of eelgrass in MBNMS

Eelgrass Beds

Eelgrass ( Zostera marina) is the only flowering plant that is able to grow underwater. Like land-bound grasses eelgrass roots itself into the substrate and produces seeds. It thrives in protected coastal waters with sandy or muddy bottoms. This fast growing plant plays a crucial role in the coastal ecosystem by providing food and shelter to a variety of animals, including juvenile fish and crabs.

Because eelgrass is a relatively stable feature in a world of swirling water and sediments, eelgrass becomes the center of a small community: shrimps and worms burrow in the root-bound sand, pipefishes hang out around the waving blades, and various fishes attached their eggs to the blades. Many juvenile fish and invertebrates find protection, food, and cover among the grass blades.


picture of giant green anemoniePiers and Wharves

Diving near piers and wharves offers an interesting opportunity to see how animals such as anemonies, sea stars, barnacles, mussels, and algae colonize man-made debris. Also, you can plan cleanup dives near piers and wharves. Divers must be careful to avoid injuries while diving near these structures because commercial vessels and people fishing from the piers may not know divers are in the area. It is always important to obtain permission from the local harbormaster before diving near a pier or wharf.


picture of mackeral in MBNMS

Open Waters

The vast pelagic realm contains marine life ranging in size from microscopic plankton to huge blue whales. Depending on the time of year, these spectacular open waters treat divers to sights of swirling anchovies, swarms of gelatinous salps, and maybe even glimpses of elusive whales or cruising sharks. Creatures of the open waters are superbly adapted to their fluid, edgeless world. Pelagic animals are designed to deal with prolems of bouyancy and avoidance of predators in a wide open environment. If you're lucky, you may be able to see seasonal visitors such as swimming snails, pelagic jellies, or the strange looking mola mola, as they travel in on waters from the California Current. Go back a few days later, and the variety of animals you see could be completely different.


For more in-depth information on the marine organisms found in the Monterey Bay National Marine Sanctuary, please visit our site characterization.

URL: http://montereybay.noaa.gov/visitor/dive/divehabitats.html    Reviewed: March 04, 2014
Web Site Owner: National Ocean Service

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