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 chains
o Algae, cyanobacteria
• , Zooplankton (animal)- herbivores that feed on
phytoplankton or other zooplankton
o 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, strongswimming 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 Temperature
o Salinity
o 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 biodiversity
o Coral reefs
o Estuaries
o Deep-ocean floor
• Biodiversity is higher
o 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 degradation
o Marine
• Coastal
• Ocean floor: effect of trawlers
o Freshwater
• Dams
• Excessive water withdrawal
Invasive Species Are
Degrading
Aquatic Biodiversity
• Invasive species
o Threaten native species
o Disrupt and degrade whole ecosystems
• Three examples
o 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.): eutrophic
o Contains invasive species
• Purple loosestrife and the common carp
• Dr. Richard Lathrop
o 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
water
o Leads to eutrophication
• Toxic pollutants from industrial and urban areas