Aquatic Ecology Notes

Aquatic Ecology Notes

Salinity • The saltiness.

Phytoplankton • Description – small drifting plants • Niche – they are producers that support most aquatic food chains • Example – cyanobacteria & many types of algae

Zooplankton • Description – herbivores that feed on phytoplankton or other zooplankton • Niche – food stock for larger consumers • Example – krill; small crustaceans

Nekton • Description – larger, strong-swimming consumers • Niche – top consumers in the aquatic ecosystem • Example – fish, turtles, and whales

Benthos • Description – bottom-dwelling creatures • Niche – primary consumers, decomposers • Example – barnacles, oysters, and lobsters

Flowing Water Ecosystems Because of different environmental conditions in each zone, a river is a system of different ecosystems.

Headwater Stream Characteristics • A narrow zone of cold, clear water that rushes over waterfalls and rapids. Large amounts of oxygen are present. Fish are also present. Ex. trout.

Downstream Characteristics • Slower-moving water, less oxygen, warmer temperatures, and lots of algae and cyanobacteria. • Energy Source: Gravity

Standing Water Ecosystems Lakes, ponds, etc.

Littoral Zone • A shallow area near the shore, to the depth at which rooted plants stop growing. Ex. frogs, snails, insects, fish, cattails, and water lilies.

Limnetic Zone • Open, sunlit water that extends to the depth penetrated by sunlight.

Profundal Zone • Deep, open water where it is too dark for photosynthesis.

Thermal Stratification Definition • The temperature difference in deep lakes where there are warm summers and cold winters.

Causes • During the summer, lakes become stratified into different temperature layers that resist mixing because summer sunlight warms surface waters, making them less dense.

Thermocline • The middle layer that acts as a barrier to the transfer of nutrients and dissolved oxygen.

Fall Turnover • As the temperatures begin to drop, the surface layer becomes more dense, and it sinks to the bottom. This mixing brings nutrients from the bottom up to the surface and sends oxygen to the bottom.

Spring Turnover • As top water warms and ice melts, it sinks through and below the cooler, less dense water, sending oxygen down and nutrients up.

Marshes • An area of temporarily flooded, often silty land beside a river or lake.

Swamps • A lowland region permanently covered with water.

Hardwood Bottomland Forest • An area down by a river or stream where lots of hardwoods, like oaks, grow.

Prairie Potholes • These are depressions that hold water out on the prairie, especially up north in Canada. It is a very good duck habitat.

Peat Moss Bog • A wet area that over time fills in (the last stage of succession is peat moss). It can be very deep. In Ireland, they burn this for wood.

Importance of freshwater wetlands • They filter & purify water. • Habitat for many animals and plants.

Historical Aspects • Developers and farmers want Congress to revise the definition of wetlands. This would make 60-75% of all wetlands unavailable for protection. The Audubon Society estimates that wetlands provide water quality protection worth $1.6 billion per year, and they say if that wetlands are destroyed, the U.S. would spend $7.7 billion to $31 billion per year in additional flood-control costs.

Estuaries Definition • A partially enclosed area of coastal water where sea water mixes with freshwater.

Salt Marshes • The ground here is saturated with water and there is little oxygen, so decay takes place slowly. It has a surface inlet and outlet, and contains many invertebrates. It is also the breeding ground for many ocean animals. Ex. crabs and shellfish.

Mangrove Forests • These are along warm, tropical coasts where there is too much silt for coral reefs to grow. It is dominated by salt-tolerant trees called mangroves (55 different species exist). It also helps to protect the coastline from erosion and provides a breeding nursery for some 2000 species of fish, invertebrates, and plants.

Importance of Estuaries • Just one acre of estuary provides $75,000 worth of free waste treatment, and has a value of about $83,000 when recreation and fish for food are included. • Prime Kansas farmland has a top value of $1,200 and an annual production value of $600.

The Everglades Problems • As Miami develops, it encroaches on everglades. Plus, it prompts people vs. wildlife. It is freshwater and local areas are draining it. Southern Florida to the Keys

Restoration • Build huge aqueduct, or find other sources of fresh water an protect it federally under endangered species act, etc.

The Water Resource Importance • Leonardo da Vinci said that “Water is the driver of nature.” Without water, the other nutrient cycles would not exist in their present forms, and current forms of life on earth could not exist.

Hydrogen Bonds Attraction Between Molecules • The strong forces of attraction between molecules of water.

Heat Capacity • Water changes temp very slowly because it can store heat. This protects living organisms from the shock of abrupt temperature changes.

Heat of Vaporization • The temperature at which water turns to vapor.

Universal Solvent • Water can dissolve a wide variety of compounds. This means it can easily become polluted by water-soluble wastes.

Expansion When Frozen • Ice has a lower density than liquid water. Thus, ice floats on water.

Surface Water • Examples – streams, rivers, and lakes • Source – precipitation • Watershed – Ex. small streams  larger streams  rivers  sea

Groundwater • Aquifers–porous rock w/ water flowing through • Water Table – the level of earth’s land crust to which the aquifer is filled • Renewability – the circulation rate of groundwater is slow (300 to 4,600 years).

Water Usage • Irrigation – watering crops • Industry – coolant (power plant) • Domestic and Municipal – drinking, sewage, bathwater, dishwater & laundry

Too Much Water • Problems include flooding, pollution of water supply, and sewage seeping into the ground.

Too Little Water Examples • Examples include drought and expanding deserts.

Overdrawing Surface Water • Lake levels drop, recreation use drops, fisheries drop, and salinization occurs. Ex. Soviet Union (Aral Sea); the inland sea drained the river that fed into it. Now it’s a huge disaster (read pg. 305 in text). 1997 1964

Aquifer Depletion • This harms endangered species, and salt water can seep in.

Salinization of Irrigated Soil • Water is poured onto soil and evaporates. Over time, as this is repeated, nothing will grow there anymore.

U.S. Water Problems Surface Water Problems • The polluted Mississippi River (non-source point pollution) has too much phosphorus. • In the Eerie Canal, which connects the ocean to the Great Lakes, lampreys came in and depleted the fish. The zebra mollusk is also a problem in the Great Lakes.

Mono Lake • (like the Dead Sea) This has a huge salt concentration due to man’s draining.

Colorado River Basin • These are dams & reservoirs that feed from the Colorado River all the way to San Diego, LA, Palm Springs, Phoenix & Mexico. So far has worked because they haven’t withdrawn their full allocations. See pg306.

Groundwater Problems • These include pollution, salt, and draining too much.

Ogallala Aquifer • This is the world’s largest known aquifer, and fuels agricultural regions in the U.S. It extends from South Dakota to Texas. It’s essentially a non-renewable aquifer from the last ice age with an extremely slow recharge rate. In some cases, water is pumped out 8 to 10 times faster than it is renewed. Northern states will still have ample supplies, but for the south it’s getting thinner. It is estimated that ¼ of the aquifer will be depleted by 2020.

Aquatic Ecology Notes