Climate and Biodiversity, Part 3

W HAT A RE THE M AJOR T YPES OF A QUATIC S YSTEMS ?  Concept 1: Saltwater and freshwater aquatic life zones cover almost three-fourths of the Earth’s surface, and oceans dominate the planet.

Most of the Earth is Covered with Water  Water covers 97% of the biosphere.  Most of this water is in the oceans.  The global ocean is one large body of water, but we divide it into five large areas: the Atlantic, Pacific, Arctic, Antarctic, and Indian Oceans.  The largest ocean is the Pacific Ocean.  The Pacific contains more than half of the Earth’s water.

 The biomes found in the water are called aquatic life zones.  The classification of aquatic life zones depends on their salt content (salinity).  Saltwater or marine life zones are the oceans and coastal systems.  Freshwater life zones are the lakes, rivers, streams, and inland wetlands.

 There are four major types of livings things in aquatic life zones.  1. Plankton are weak swimmers and float in the water.  Phytoplankton are tiny plants like algae.  Zooplankton are tiny animals that eat other zooplankton jellyfish  Ultraplankton are bacteria that do photosynthesis.  2. Nekton are strong swimmers like fish, turtles, and whales.  3. Benthos are animals that live on the bottom of the ocean like clams, lobsters, and oysters.  4. Decomposers are also in the ocean.

 There are factors that determine which organisms can live in the different aquatic life zones:  1.water temperature  2.amount of oxygen dissolved in the water  3.amount of food available  4.amount of light available

W HY A RE M ARINE A QUATIC S YSTEMS I MPORTANT AND H OW H AVE H UMAN A CTIVITIES A FFECTED T HEM ?  Concept 1: Saltwater ecosystems are irreplaceable reservoirs of biodiversity, providing major ecological and economical services that are being threatened by human activities.

Oceans Provide Vital Ecological and Economic Services  The ocean has a large amount of biodiversity.  The ocean has three main parts: the coastal zone, the open sea, and the ocean bottom.  The coastal zone is the warm, nutrient-rich, shallow water that stretches from the high tide mark to the edge of the continent.  90% of all ocean species live in the coastal zone.

Estuaries and Coastal Wetlands Are Highly Productive  An estuary is where a river meets the ocean.  The saltwater from the ocean mixes with the freshwater of the river.  Estuaries contain many nutrients washed out of the river.  Estuaries are associated with coastal wetlands.  Coastal wetlands are covered with water all or part of the year.

 Animals that live in estuaries and other coastal wetlands must be able to deal with daily and seasonal changes in their environment.  The speed of the river, the salt content, and the water temperature can change quickly.  Since the estuaries contain so many nutrients, many animals use estuaries as nurseries for their young.

The Open Sea and the Ocean Floor Host a Variety of Species  The open sea is the part of the ocean that is far away from land and is very deep.  The open sea is divided into zones.  The euphotic zone is the upper part of the ocean that receives sunlight.  Phytoplankton perform photosynthesis in the euphotic zone.  Many fast-swimming fish like tuna and sharks live in the euphotic zone.

 The bathyal zone is the dimly-lit middle area on the ocean.  It is under the euphotic zone.  Very little sunlight reaches the bathyal zone.  No photosynthesis occurs in the bathyal zone.  Many of the animals that live in the bathyal zone travel to the surface at night to feed.

 The abyssal zone is the deepest zone of the ocean.  It is dark and very cold.  There is no photosynthesis occurring in the abyssal zone and there is very little oxygen.  The animals in the abyssal zone get their food from dead organisms that drift down from the upper zones of the ocean.  Pieces of dead organisms drifting down in the ocean are called marine snow.

Human Activities Are Disrupting and Degrading Marine Ecosystems  Many people want to live near a coast.  Nearly 50% of the population of the US lives along or near the coast.  This results in degradation of the ocean.  It is difficult for us to know how our activity will affect the ocean because it is the least explored region on Earth.

W HAT A RE THE M AJOR T YPES OF F RESHWATER S YSTEMS AND H OW H AVE H UMAN A CTIVITIES A FFECTED T HEM ?  Concept 1: Freshwater lakes, rivers, and wetlands provide important ecological and economic services that are being disrupted by human activities.

Water Stands in Some Freshwater Systems and Flows in Others  Lakes, ponds, and inland wetlands are standing bodies of freshwater.  Rivers and streams are flowing systems of freshwater.  Lakes are formed when precipitation, run-off, streams, and rivers fill depressions in the Earth’s surface.

 Large lakes have zones, just like the ocean.  Ecologists group lakes based on their nutrient content.  Oligotrophic lakes do not have many nutrients.  These lakes tend to be deep with steep banks.  The water is crystal clear and small populations of fish live there.  Eutrophic lakes have large amounts of nutrients.  These lakes tend to have murky brown or green water.  Many algae live in these lakes.

 Services that wetlands provide:  Filter out pollutants  Reduce flooding  Maintain biodiversity  Provide recreation