Aquatic Communities Aquatic communities can be classified as freshwater or saltwater. The two sets of communities interact and are joined by the water cycle. Gravity eventually returns all fresh water to the sea, but meanwhile, it is contained as standing water in lakes and ponds, or as flowing water within streams and rivers. 35-1
Freshwater and saltwater communities 35-2
Lakes Lakes are bodies of freshwater often classified by their nutrient status. Oligotrophic lakes are nutrient-poor and have low productivity. Eutrophic lakes are nutrient-rich and have high productivity. Through the activities of both nature and humans, oligotrophic lakes become eutrophic through large inputs of nutrients; this is called eutrophication. 35-3
Types of lakes 35-4
Standing-Water Ecosystems Microscopic floating organisms in lakes are called plankton; phytoplankton are photosynthesizing algae, and zooplankton are the tiny animals that eat them. 35-5
Freshwater Wetlands A wetland is an ecosystem in which water either covers the soil or is near the surface The three main types of freshwater wetlands are bogs (depressions where water collects), marshes (at river edge has grasses), and swamps (has trees and shrubs) 35-6
Estuaries An estuary is a partially enclosed body of water where fresh water and salt water mix. Organisms living there must be able to tolerate brackish water (mix of salt and fresh water). Estuaries trap nutrients delivered by rivers and act as nurseries for larval fish. Estuaries are the feeding grounds for man, birds, fish, and shellfish. 35-7
Estuaries Near the mouth of a river, a salt marsh in the temperate zone or a mangrove swamp in the subtropical and tropical zones is likely to develop. 35-8
Estuary structure and function 35-9
Types of estuaries 35-10
Marine Ecosystems Photic Zone: region of the ocean that light penetrates Aphotic Zone: permanently dark In addition to the division between photic and aphotic zones, marine biologists divide the ocean into zones based on the depth and distance from shore: the intertidal zone the coastal ocean the open ocean 35-11
Land Coastal ocean Marine Ecosystems 200 m 1,000 m Photic zone Open ocean 4,000 m 6,000 m Aphotic zone Continental shelf Continental slope and continental rise Abyssal plain Ocean trench 10,000 m Copyright Pearson Prentice Hall
Marine Ecosystems Intertidal Zone Organisms that live in the intertidal zone are exposed to regular and extreme changes in their surroundings. Competition among organisms in the rocky intertidal zone often leads to zonation, the prominent arrangement of organisms in a particular habitat in horizontal bands.
Coastal Ocean Marine Ecosystems The coastal ocean extends from the low-tide mark to the outer edge of the continental shelf. It falls within the photic zone, and photosynthesis occurs throughout its depth. The coastal ocean is often rich in plankton and many other organisms. Copyright Pearson Prentice Hall
Kelp forests are named for their dominant organism, a giant brown alga. Kelp forests are one of the most productive coastal ocean communities. Kelp forests support a complex food web. Marine Ecosystems Copyright Pearson Prentice Hall
Coral reefs are areas of biological abundance found in shallow, warm tropical waters. Their chief constituents are stony corals with a limestone exoskeleton, and red and green algae.. 35-17
Open Ocean Marine Ecosystems The open ocean, the oceanic zone, extends from the edge of the continental shelf outward. It is the largest marine zone. Most of the photosynthetic activity on Earth occurs in the photic zone of the open ocean by the smallest producers. Copyright Pearson Prentice Hall
Benthic Zone The benthic zone includes organisms living on or in the ocean floor Organisms of the benthic zone (benthos) depend on the debris that floats down from above. 35-19
Ocean inhabitants 35-20
Chapter Summary The spherical earth causes different amounts of sunlight to be received at different latitudes, resulting in differences in temperature from the equator to the poles. The tilt and rotation of the earth cause the four seasons. Rising and falling air currents trigger moist or dry areas across the globe. 35-21
Topography also influences rainfall patterns. Terrestrial biomes are distributed according to climate; moisture and temperature determine major types of vegetation. Terrestrial biomes include tundra, coniferous forest (taiga), temperate deciduous forest, tropical rain forest, shrublands, grasslands, savanna, and deserts. Each biome has characteristic organisms. 35-22
Streams, rivers, lakes, ponds, and wetlands are different freshwater communities. 35-23
4-4 The photic zone is A. Found in the intertidal zone B. Where light penetrates C. contains plankton D. all of the above Copyright Pearson Prentice Hall
4-4 Coastal wetlands that are widespread in tropical regions such as southern Florida and Hawaii are known as detritus. bogs. mangrove swamps. benthos. Copyright Pearson Prentice Hall
4-4 Coral animals cannot grow in water that contains salt. contains oxygen. is cold. receives sunlight. Copyright Pearson Prentice Hall
4-4 The zone that covers the ocean floor is the benthic zone. abyssal plain. continental shelf. continental rise. Copyright Pearson Prentice Hall