1. Chapter 6 Aquatic Biodiversity
Mandi Blanks

2. Vocabulary
Benthos: bottom dwellers such as barnacles and oysters that anchor themselves to one spot, worms that burrow into the sand or mud, & lobsters and crabs that walk about on the bottom
Coastal wetlands: land areas covered with water all or part of the year
Coastal zone: warm, nutrient-rich, shallow water that extends from the high-tide mark on land to gently-sloping, shallow edge of the continental shelf

3. Vocabulary
Cultural eutrophication: human inputs of nutrients from the atmosphere and from nearby urban and agricultural areas can accelerate the eutrophication of lakes
Decomposers: (mostly bacteria) that break down the organic compounds in the dead bodies and wastes of aquatic organisms into simple nutrient compounds for use by aquatic producers
Drainage basin: the land area that delivers runoff, sediment, and dissolved substances to a stream

4. Vocabulary
Estuary: partially enclosed coastal area at the mouth of a river where its fresh water, carrying fertile silt and runoff from the land, mixes with salty seawater
Eutrophic lake: lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates. Compare mesotrophic lake, oligotrophic lake
Surface water: precipitation that does not infiltrate the ground or return to the atmosphere by evaporation or transpiration
Inland wetland: land away from the coast, such as a swamp, marsh, or bog, that is covered all or part of the time with fresh water

5. Vocabulary
Intertidal zone: the area of shoreline between low and high tides
Lake: large natural body of standing fresh water formed when water from precipitation, land runoff, or groundwater flow fills a depression in the earth created by glaciation, earth movement, volcanic activity, or a giant meteorite
Mesotrophic lake: lake with a moderate supply of plant nutrients
Nekton: strongly swimming organisms found in aquatic systems

6. Vocabulary
Oligotrophic lake: lake with a low supply of plant nutrients
Open sea: the part of an ocean that is beyond the continental shelf
Plankton: small plant organisms (phytoplankton) and animal organisms (zooplankton) that float in aquatic ecosystems
Runoff: fresh water from precipitation and melting ice that flows on the earth's surface into nearby streams, lakes, wetlands, and reservoirs

7. Vocabulary
Ultraplankton: photosynthetic bacteria no more than 2 micrometers wide
Watershed: land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river)
Zooplankton: animal plankton. Small floating herbivores that feed on plant plankton (phytoplankton)

8. Objectives
What are the basic types of aquatic life zones, and what factors influence the kinds of life they contain?
Three layers of aquatic life zones can be used: surface, middle, and bottom.
1. Temperature, sunlight availability, dissolved oxygen, and nutrient availability determine types and numbers of producers found in these zones.
2. Euphotic zone: upper layer where sunlight can penetrate. Clouding or excessive algal growth reduces depth; Dissolved oxygen levels are higher near the surface due to photosynthesis in this area.
3. CO2 levels are lower near the surface and higher in deeper, darker layers due to aerobic respiration.
4. Open oceans tend to have limited amounts of nitrates, phosphates, iron, and other nutrients that limit productivity.
5. Shallow waters are generally well supplied with nutrients for growth.
6. Deep dwelling species depend on animal and plant material that die/float to the bottom. Large fish are vulnerable to overfishing depletion.

9. Objectives
What are the major types of saltwater life zones, and how do human activities affect them?
A. Oceans have two major life zones: the coastal zone and the open sea.
B. The coastal zone interacts with the land and is much affected by human activities.
1. Ecosystems in coastal zones have a high net primary productivity per unit area. They constitute 10% of the oceans and contain 90% of all marine species.
2. There is ample sunlight and nutrient flow from land, and wind/currents distribute them.
3. The coastal zone extends from the high-tide mark on land to the edge of the continental shelf.
4. Estuaries and coastal wetlands are subject to tidal rhythms, runoff from land, and seawater that mixes with freshwater and nutrients from rivers and streams.
5. Mangrove forest swamps grow in sheltered regions of tropical coasts. They collect mud and anaerobic sediment.
6. Coastal wetlands/estuaries make nutrients available due to constant stirring of bottom sediment.
7. These areas filter toxic pollutants and excess plant nutrients, reduce storm damage, and provide nursery sites for aquatic species.
8. Humans are destroying/degrading these ecosystems; one-third have already been lost.

10. Objectives
What are the major types of freshwater life zones, and how do human activities affect them?
A. Freshwater life zones contain less than 1% by volume of salt. These zones include standing (lentic) bodies such as lakes, ponds, and wetlands and flowing (lotic) systems such as streams and rivers.
B. Lakes are large natural bodies of standing water found in depressions.
1. Rainfall, melting snow, and stream drainage feed lakes.
2. Lakes generally consist of four distinct zones depending on depth and distance from shore.
a. The littoral zone is shallow, sunlit water near the shore.
b. The limnetic zone is open, sunlit surface water away from shore and is the most productive area for food and oxygen production.
c. The profundal zone is deep, open water too dark for photosynthesis. Oxygen levels are lower.
d. The benthic zone consists of decomposers and detritus feeders. Fish swim from one zone to another. Sediment washing and dropping detritus feed this area.
C. Stratification of water occurs in deep temperate lakes into temperature zones; no mixing occurs.
D. During fall and spring, lakes have turnover of water that brings up nutrients, reoxygenates bottom levels, and evens out water temperature.