Marine Ecosystems
Chapter 7.2
Natural Capital
© 2004 Brooks/Cole – Thomson Learning
Marine Ecosystems
Ecological
Services
Economic
Services
Climate moderation
Food
CO2 absorption
Animal and pet
feed (fish meal)
Nutrient cycling
Pharmaceuticals
Waste treatment
and dilution
Reduced storm
impact (mangrove,
barrier islands,
coastal wetlands)
Habitats and
nursery areas for
marine and
terrestrial species
Genetic resources
and biodiversity
Harbors and
transportation
routes
Coastal habitats
for humans
Recreation
Employment
Offshore oil and
natural gas
Minerals
Scientific
information
Building materials
Categories of marine
ecosystems
1. Coastal ecosystems – includes:
estuaries, salt marshes, mangrove
swamps, rocky and sandy shores
2. Coral reefs
3. Oceans
Estuaries
Definition: an area in which fresh water from a
river mixes with salt water from the ocean; a
transition area from the land to the ocean
Other names: bay, sound, lagoon, harbor, bayou
The Ocean
Area where
fresh and salt
water mix
River bringing
freshwater to
the sea
Characteristics of
Estuaries
Water is brackish: a mixture of
freshwater and saltwater
There is a gradient (gradual
change) in the salinity
 near the input from the river: 0-5 ppt
 in the middle of the estuary: 5-25ppt
 at the ocean: >25 ppt
(ppt = parts per thousand, a unit for
salinity)
Mobile Bay – one of the
largest estuaries in the U.S.
Tensaw River
Mobile River
What is the
approximate
salinity in ppt
for these
locations?
Mobile Bay
Gulf of Mexico
Dauphin Island
Characteristics of
Estuaries
Very nutrient rich ecosystems
 leads to high productivity
and high biodiversity
Fast-moving rivers and waves
carry nutrient-rich particles
Sediment settles out in the
estuary when the water
slows down
It accumulates on the bottom
(benthic zone)
Great place for plants to grow!
Important
functions of
estuaries: for
living things
1.
2.
3.
4.
habitat
nursery
fisheries
recreation
Important functions of
estuaries: related to water
5. Water purification
6. Flood control (from upstream)
7. Buffer land from hurricanes, absorb storm
surge
Loss of coastal
wetlands in
Louisiana made
Hurricane
Katrina’s effect
worse than it
would have been
Estuary plants
Plants must be adapted to salty habitat
eelgrass
cordgrass
glasswort – a succulent
Estuary plants
Narrow leaved cattail
Estuary animals
Huge variety!
Including… horseshoe
crabs
Mosquito…
Estuary animals
oysters
lobster
Estuary animals
Flounder
Striped Bass
Estuary animals
Many, many birds!
Common tern
Great White Egret
Estuary animals
Manatee
Estuary animals
Sea lions at Pier 39 in
San Francisco Bay
Salt Marshes
Definition: a low area that is subject to regular, but
gentle, tides
Dominated by grasses
(Remember, marshes do not have trees or shrubs)
Location: Gulf of Mexico and Atlantic coast
Texas salt marsh
Alabama
salt marsh
Dauphin Island,
AL
Mangrove
Swamps
Definition: coastal
wetlands located in
tropical and
subtropical zones;
characterized by
salt-tolerant trees
and shrubs, such as
mangrove trees
Mangroves
Different species – include red mangrove…
with tangled roots that reach above the
water line, form an important habitat for
many animals
Rocky shores
Also called rocky intertidal
zone – many places to
live in this habitat,
means high biodiversity
Organisms must be
adapted to wave action,
changing tide levels
Some examples of rocky
shores organisms are at
the Monterey Bay
Aquarium website below:
http://www.montereybayaq
uarium.org/efc/efc_rocky
/rocky_cam.asp#
Rocky Shores
At low tides, there are
often tide pools left
behind where you
can see starfish,
anemones, crabs,
octopus
Sea star
Rocky Shore Beach
Hermit crab
Shore crab
High tide
Periwinkle
Sea urchin
Anemone
Mussel
Low tide
Sculpin
Barnacles
Kelp
Monterey flatworm
Nudibranch
Sea lettuce
Sandy shores
“The Beach!”
Sandy Shores
Not as much biodiversity as rocky shores – Why?
1. not much habitat diversity
2. sand dries out at low tide
some small things can live in the sand, food for
shorebirds
Barrier Islands
Narrow islands made of
sand that provide a
buffer for the
mainland from the
sea
Constantly shifting,
especially with
storms
Ex: Dauphin Island,
Alabama
Barrier
beach
Beach flea
Peanut worm
Tiger beetle
Blue crab
Clam
Dwarf
olive
High tide
Sandpiper
Silversides
Mole
shrimp
Low tide
White sand
macoma
Sand dollar
Moon snail
Ghost
shrimp
Barrier Islands
Ocean
Beach
Primary Dune
Intensive recreation,
no building
Trough
Secondary Dune
No direct
Limited
passage
recreation
or building and walkways
Grasses or shrubs
No direct
passage
or building
Back Dune
Bay or
Lagoon
Most suitable
for development
Intensive
recreation
Bay shore
No filling
Taller shrubs
Taller shrubs and trees
Think about ecological succession as you move away from
the ocean. What is the “disturbance” in this ecosystem?
Notice the beach erosion. Barrier islands are
constantly changing.
This picture was taken from Dauphin Island, AL. Notice the offshore
platforms for drilling natural gas in the Gulf of Mexico. Interestingly,
Florida does not allow offshore drilling. Why?
Coral Reefs
 Structures in the shallow oceans that are built by
animals called corals; serve a habitat for many diverse
organisms
 Require two things: warm temperatures and sunlight
 Found between 30°N and 30°S of the equator
Coral Reefs
Corals are animals that belong to the phylum Cnidaria,
the stinging-celled animals such as jellyfish and hydra
Coral polyps resemble small sea anemones with
tentacles that can sting and paralyze prey
Coral Reefs
They build limestone
houses around
themselves and stay
in one spot (sessile)
Over many
generations, the
limestone builds up
to form a large reef
(takes a long time)
Polyps in limestone skeleton
Elkhorn coral
Coral Reefs
Corals live in a symbiotic
relationship with algae
called zooxanthellae; the
algae are photosynthetic
and give the coral food
and oxygen; the algae
get carbon dioxide and
nutrients from the
nitrogenous wastes of
the coral
Coral Reefs
There are many different kinds of corals:
Soft corals
Hard corals
Coral Reefs
Growing on the reef
with the corals are
other animals, such
as sponges, worms,
shrimps, crabs,
mollusks
Living in and around
the reef are fish, sea
turtles, sea snakes,
marine mammals
Coral Reef Destruction
1. Coral bleaching – when
temperatures go above
normal, the zooxanthellae
(algae) in the coral can be
rejected, the coral turns a
whitish color and dies
Natural causes: El Nino
Manmade causes: Global
warming
Coral Reef Destruction
2. Physical damage
Ships, anchors, tourist divers
Dynamite fishing - reefs are damaged by
physical destruction that may occur when
people collect fish
Coral Reef Destruction
3. Land development and pollution – loss
of mangrove forests means more
nutrients and sediments flow out to the
sea; coral may die from sediment or
algal blooms
4. Fish and coral trade
5. Increased exposure to UV due to ozone
depletion
Ocean: Deep and Wide
Defining characteristics: light and depth of water
Varying surface of ocean floor: continental shelf, slope, trenches
(deepest is Mariana Trench at about 35,000 feet below sea level),
plains, geologic features (hydrothermal vents, volcanoes, fault
lines that produce earthquakes and tsunamis)
High tide
Low tide
Sun
Sea level
50
Euphotic Zone
100
Estuarine
Zone
Continental
shelf
Photosynthesis
0
200
500
Bathyal Zone
1,000
Twilight
Coastal Zone Open Sea
Depth in
meters
1,500
Euphotic zone – full sunlight, phytoplankton
(the producers), zooplankton, nekton
Bathyal zone – the twilight zone
Abyssal zone – cold, dark, pressure high,
specialized “weird” organisms live here
Benthic zone – all along the ocean bottom,
benthos are organisms that live on the
bottom
of –the
ocean,
filter feeders,
© 2004
Brooks/Cole
Thomson
Learning
scavengers, decomposers
Abyssal Zone
3,000
4,000
5,000
10,000
Darkness
2,000
Deep ocean
Characteristics: dark, cold, high pressure
How can anything live there?
What is the base of the food chain?
Two ways:
1. marine snow – organic particles that settle down
from above
2. hydrothermal vents - cracks in the earth that allow
hot gases to escape, certain bacteria can make food in
these conditions (chemosynthesis)
Will see both of these in the Planet Earth video….
Biodiversity in marine
ecosystems
Why do coral reefs have more biodiversity than
the open ocean or the deep ocean?
More sunlight and more habitat support greater
diversity of species
Natural Capital Degradation
Marine Ecosystems
Half of coastal wetlands lost
to agriculture and urban
development
Over one-third of mangrove
forests lost since 1980 to
agriculture, development, and
aquaculture shrimp farms
About 10% of world’s beaches
eroding because of coastal
development and rising sea
level
Ocean bottom habitats
degraded by dredging and
trawler fishing boats
Over 25% of coral reefs
severely damaged and 11%
have been destroyed