Marine Ecosystems Marine ecosystems Why the Ocean Matters

Marine and coastal ecosystems Regions of ocean water differ greatly Some zones support more life than others Photic zone = well-lighted top layer Absorbs 80% of solar energy Supports high primary productivity Pelagic = habitats and ecosystems between the ocean’s surface and floor Benthic = habitats and ecosystems on the ocean floor Most ecosystems are powered by solar energy But even the darkest depths host life Deep Sea Life

Open ocean systems vary in biodiversity Microscopic phytoplankton are the base of the marine food chain Algae, protists, cyanobacteria They feed zooplankton Which then feed fish, jellyfish, whales, etc. Predators at higher trophic levels Larger fish, sea turtles, sharks, and fish-eating birds

Animals of the deep ocean Animals adapt to extreme water pressure and the dark Scavenge carcasses or organic detritus Predators Others have mutualistic relationships with bacteria Some carry bacteria that produce light chemically by bioluminescence Hydrothermal vents support tubeworms, shrimp, and other chemosynthetic species bioluminescence Hydrothermal vents

Kelp forests harbor many organisms Kelp = large, dense, brown algae growing from the floor of continental shelves Dense strands form kelp forests along temperate coasts They provide shelter and food for organisms They absorb wave energy and protect shorelines from erosion People use it in food, cosmetics, paints, paper, soap, etc. Kelp

Coral reefs are treasure troves of biodiversity Coral reef = a mass of calcium carbonate composed of the skeletons of tiny marine animals (corals) They may be an extension of a shoreline Or exist along a barrier island, parallel to the shore Or as an atoll (a ring around a submerged island) Corals = tiny colonial invertebrate animals Related to sea anemones and jellyfish Attach to a rock or reef and capture passing food with stinging tentacles Get food from symbiotic algae (zooxanthallae) Coral video coral

Most corals are colonial Reefs consist of millions of densely packed animals Reefs are located in shallow subtropical and tropical waters Protect shorelines by absorbing waves Innumerable invertebrates and fish species find food and shelter in reef nooks and crannies

Coral reefs are in worldwide decline “Coral bleaching” = occurs when zooxanthellae leave the coral or die Corals lose their color and die, leaving white patches From climate change, pollution, or unknown natural causes Nutrient pollution causes algal growth Which smothers coral Divers damage reefs by using cyanide to capture fish Acidification of oceans deprives corals of carbonate ions for their structural parts Coral bleaching Acid sea

Deepwater coral reefs exist They thrive in waters outside the tropics On ocean floor at depths of 200–500 m (650–1,650 ft) Occur in cold-water areas off the coasts of Spain, the British Isles, and elsewhere Little is known about these reefs Already, many have been badly damaged by trawling Some reefs are now being protected Deep water coral reefs

Intertidal zones undergo constant change Intertidal (littoral) ecosystems = where the ocean meets the land Between the uppermost reach of the high tide and the lowest limit of the low tide Tides = periodic rising and falling of the ocean’s height due to the gravitational pull of the sun and moon Intertidal organisms spend part of their time submerged in water and part of their time exposed to sun and wind Surf the Dragon

A typical intertidal zone

Intertidal zones are a tough place to live But they have amazing diversity Rocky shorelines, crevices, pools of water (tide pools) Anemones, mussels, barnacles, urchins, sea slugs Starfish and crabs Temperature, salinity, and moisture change dramatically from high to low tide Sandy intertidal zones have slightly less biodiversity tides Intertidal zone

Salt marshes line temperate shorelines Salt marshes = occur along coasts at temperate latitudes Tides wash over gently sloping sandy, silty substrates Tidal creeks = channels that rising and falling tides flow into and out of Salt marshes have very high primary productivity Critical habitat for birds, commercial fish, and shellfish They filter pollution They stabilize shorelines against storm surges a Salt marsh 16

People change and destroy salt marshes People want to live or do business along coasts We lose key ecosystem services Flooding (e.g., from Hurricane Katrina) worsens

Mangrove forests line coasts In tropical and subtropical latitudes They replace salt marshes along sandy coasts Mangroves = salt-tolerant trees Their unique roots curve up for oxygen and down for support Nesting areas for birds Nurseries for fish and shellfish Mangroves provide food, medicine, tools, and construction materials

Mangrove forests have been destroyed Half the world’s mangrove forests are gone Developed for residential, commercial, and recreational uses Shrimp farming Once destroyed, coastal areas no longer: Slow runoff Filter pollutants Retain soil Protect communities against storm surges National Geographic Mangrove Pic

Fresh and salt water meet in estuaries Estuaries = water bodies where rivers flow into the ocean, mixing fresh and salt water They are biologically productive Have fluctuations in salinity Critical habitat for shorebirds and shellfish Transitional zone for fish that spawn in streams and mature in salt water They have been affected by development, pollution, habitat alteration, and overfishing NOAA Estuaries EPA Estuaries

II Marine and Coastal Ecosystems Where in the oceans are productive areas of biological activity likely to be found? Describe three kinds of ecosystems found near coastal areas and the types of life they support. Why are coral reefs biologically valuable? How are they being degraded by human impact? What is causing the disappearance of mangrove forests and salt marshes?

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