Marine Organisms and Niches

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

Southern Florida to the Keys

Case Study: Restoring the Florida

Everglades

• The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities.o 90% of park’s wading birds have vanished.o Other vertebrate populations down 75-95%.o Large volumes of water that once flowed through the park have been diverted

for crops and cities.o Runoff has caused noxious algal blooms.

Problems• As Miami develops, it encroaches on everglades. Plus,

it prompts people vs. wildlife. It is freshwater and local areas are draining it.

Restoring the Florida Everglades

• The project has been attempting to restore the Everglades and Florida water supplies.

Figure 12-10

Restoration• Build huge aqueduct, or find

other sources of fresh water an protect it federally under endangered species act, etc.

SALTWATER LIFE ZONES

• The oceans that occupy most of the earth’s surface provide many ecological and economic services.

Figure 6-4

Marine Ecosystems

• Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems.

Figure 6-4

Marine Biomes

Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms.o Plankton: important group of weakly swimming, free-floating biota.

• Phytoplankton (plant)- Producers that support most aquatic food chainso Algae, cyanobacteria

• , Zooplankton (animal)- herbivores that feed on phytoplankton or other zooplanktono Krill, small crustaceans

o Necton: fish, turtles, whales• top consumers in the aquatic ecosystem

o Benthos: bottom dwellers (barnacles, oysters).• primary consumers, decomposers

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

The Coastal Zone: Where Most of the

Action Is• The coastal zone: the warm, nutrient-rich, shallow

water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf.

• The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species.o Provides numerous ecological and economic services.o Subject to human disturbance.

Biological Zones in the Open Sea: Light Rules

• Euphotic zone: brightly lit surface layer. o Nutrient levels low, dissolved O2 high, photosynthetic activity.

• Bathyal zone: dimly lit middle layer.o No photosynthetic activity, zooplankton and fish live there and migrate to

euphotic zone to feed at night.

• Abyssal zone: dark bottom layer. o Very cold, little dissolved O2.

Rocky and Sandy Shores:

Living with the Tides• Organisms in intertidal

zone develop specialized niches to deal with daily changes in:o Temperatureo Salinityo Wave action

Figure 6-9

Threats to Coral Reefs:

Increasing

Stresses• Biologically diverse

and productive coral reefs are being stressed by human activities.

Figure 6-11

Core Case Study:Why Should We Care About Coral Reefs?

• Coral reefs form in clear, warm coastal waters of the tropics and subtropics.o Formed by massive colonies

of polyps.

Figure 6-1

Core Case Study:Why Should We Care About Coral Reefs?

• Help moderate atmospheric temperature by removing CO2 from the atmosphere.

• Act as natural barriers that help protect 14% of the world’s coastlines from erosion by battering waves and storms.

• Provide habitats for a variety of marine organisms.

We Have Much to Learn about Aquatic Biodiversity

• Greatest marine biodiversityo Coral reefso Estuaries o Deep-ocean floor

• Biodiversity is highero Near the coast than in the open sea o In the bottom region of the ocean than the surface region

Human Activities Are Destroying and Degrading

Aquatic Habitats

• Habitat loss and degradationo Marine

• Coastal• Ocean floor: effect of trawlers

o Freshwater• Dams• Excessive water withdrawal

Invasive Species Are Degrading Aquatic Biodiversity

• Invasive species o Threaten native specieso Disrupt and degrade whole ecosystems

• Three exampleso Water hyacinth: Lake Victoria (East Africa)o Asian swamp eel: waterways of south Florida o Purple loosestrife: indigenous to Europe

• Treating with natural predators—a weevil species and a leaf-eating beetle—Will it work?

Science Focus: How Carp Have Muddied Some Waters

• Lake Wingra, Wisconsin (U.S.): eutrophico Contains invasive species

• Purple loosestrife and the common carp

• Dr. Richard Lathropo Removed carp from an area of the lake

• This area appeared to recover

Population Growth and Pollution Can Reduce Aquatic Biodiversity

• Nitrates and phosphates mainly from fertilizers enter watero Leads to eutrophication

• Toxic pollutants from industrial and urban areas