© Cengage Learning 2015 LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER SCOTT E. SPOOLMAN © Cengage Learning Aquatic Biodiversity

© Cengage Learning 2015 Biodiversity Coral reefs form in clear, warm coastal waters in tropical areas –Tiny animals (polyps) and algae have a mutualistic relationship –Polyps secrete calcium carbonate shells, which become coral reefs Core Case Study: Why Should We Care about Coral Reefs?

© Cengage Learning 2015 Provide important ecological and economic services Vulnerable to damage –Warmer ocean temperatures leading to coral bleaching Kills algae and thus the polyps –Increasing ocean acidity Core Case Study: Why Should We Care about Coral Reefs? (cont’d.)

Fig. 8-1, p. 168 Core Case Study: Why Should We Care about Coral Reefs? (cont’d.)

© Cengage Learning 2015 Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface, with oceans dominating the planet Key factors determining biodiversity in aquatic systems –Temperature, dissolved oxygen content, availability of food, and access to light and nutrients necessary for photosynthesis 8-1 What Is the General Nature of Aquatic Systems?

© Cengage Learning 2015 Saltwater – 71% of the earth’s surface 97.5 % of earth’s water Global ocean divided into four areas –Atlantic Ocean –Pacific Ocean –Arctic Ocean –Indian Ocean Freshwater – 2.2% of the earth’s surface % of earth’s water Most of the Earth Is Covered with Water

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Fig. 8-2, p. 169 Ocean hemisphereLand–ocean hemisphere Pacific Ocean Covers 1/3 earth’s surface Contains ½ earth’s water Most of the Earth Is Covered with Water

© Cengage Learning 2015 Aquatic life zones –Saltwater life zones (marine life zones) Oceans and estuaries Coastal wetlands and shorelines Coral reefs Mangrove forests –Freshwater life zones Lakes, rivers, and streams Inland wetlands Most of the Earth Is Covered with Water

© Cengage Learning 2015 Saltwater and freshwater life zones contain several major types of organisms: –Plankton –Nekton –Benthos –Decomposers Aquatic Species Live in Top, Middle, or Bottom Layers of Water Plankton Nekton Benthos Decomposers

© Cengage Learning 2015 Plankton – drifting –Phytoplankton –Zooplankton Aquatic Species Live in Top, Middle, or Bottom Layers of Water

© Cengage Learning 2015 Phytoplankton Microscopic photosynthetic organisms that live in saltwater and freshwater life zones Primary producers for most aquatic food chains Produce 50% of the world's oxygen Fix 30-60% of the world’s carbon Cyanobacteria and Algae Aquatic Species Live in Top, Middle, or Bottom Layers of Water Although phytoplankton account for only 1 – 2 % of the total global biomass, they are responsible for producing 30 – 60 % of the global annual fixation of carbon on Earth.

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Zooplankton Unicellular protozoa to large invertebrates like jellyfish Some are primary consumers (protozoa) feed on phytoplankton Some are secondary consumers feed on other zooplankton Copepods, krill, daphnia, jellyfish, & larvae of some animals. Aquatic Species Live in Top, Middle, or Bottom Layers of Water

© Cengage Learning 2015 –Nekton –Benthos –Decomposers Aquatic Species Live in Top, Middle, or Bottom Layers of Water

© Cengage Learning 2015 Nekton –Strong swimmers – fish, turtles, whales Benthos –Bottom dwellers – oysters, sea stars, clams, worms, lobsters, crabs Decomposers –Mostly bacteria Aquatic Species Live in Top, Middle, or Bottom Layers of Water Plankton Nekton Benthos Decomposers

© Cengage Learning 2015 Key factors in the distribution of organisms –Temperature –Dissolved oxygen content –Availability of food –Availability of light and nutrients needed for photosynthesis –Absence/Presence of currents –Turbidity (Degree of cloudiness in water; Inhibits photosynthesis) Aquatic Species Live in Top, Middle, or Bottom Layers of Water