Transcript Unit 3: Seaweeds & Coastal Communities

Unit 3:
Coastal
Communities
Structure of a Typical Marine
Alga
• Absorption of water and
nutrients occurs throughout the
thallus, so there is no conducting
tissue
• Holdfast: root-like structure that
secures seaweed to substrate
• Stipe: stem-like structure that
allows the blades to reach
sunlight and absorbs shock by
bending with waves
• Blade: leaf-like structure,
symmetrical with equal stomata
and chlorophyll on both sides.
Contains reproductive
structures.
Algae Structure, cont.
• Air bladder: also called pneumatocyst, hollow CO filled
floats. In brown algae (kelp) only, holds blades close to
the light at the surface.
Phylum Chlorophyta:
Green Algae
• Chlorophyll = green
• 10% marine, upper
intertidal
• Examples:
• Ulva (sea lettuce)
• Cladophora
• Codium (dead man’s
fingers)
Phylum Phaeophyta:
Brown Algae
• Largest and
most complex
• Chlorophyll
masked by
fucoxanthin
• Examples:
• Fucus
(Rockweed)
• Macrocystis
(Kelp)
• Laminaria
(Oarweed)
Phylum Rhodophyta:
Red Algae
• Chlorophyll
masked by
phycoerythrin
• Subtidal to 200m
• Examples:
• Gigartina (Turkish
Towel)
• Corraline Algae
• Porphyra (Nori)
Ulva Life Cycle
•2n = diploid
•1n = haploid
•Sporophyte
produces spores by
meiosis
•Spores grow into
gametophyes
•Gametophyte
produces gametes
by mitosis
•Sporophyte identical
to gametophyte
•Zygote, a result of
fertilization, a union
of gametes, grows
into sporophyte
Kelp Life Cycle
• Sporophyte
produces spores by
meiosis
• Spores grow into
gametophytes
• Gametophytes
produce gametes
by mitosis
• Sporophyte is
large, gametophyte
is microscopic.
• Gametes unite into
zygote which grows
into sporophyte.
Seagrasses
• The only marine
flowering plants
• Have true roots,
stems and leaves
• Live completely
submerged
• Pollen release is
timed to coincide
with spring tides
• Seeds have bristles
for attachment
• Can reproduce
asexually by
rhizomes
Uses for Marine Plants
• Seagrasses are used to filter sewage, in the
production of paper, for fertilizer, and their
rhizomes can be eaten.
• Seaweeds can be eaten, are used in
medicine, are a source of methane for fuel,
are used in fertilizers, ice cream, chocolate
milk, shampoo, lipstick, agar for bacterial
growth, laminaria is a cervix dilater.
• Marine plants are important to their own
environment because of their productivity,
they prevent the removal of substrate, they
filter water and provide habitat for animals.
Modes of Feeding
• Deposit Feeders: feed on detritus that has settled
on the bottom. e.g. sea cucumbers
• Suspension Feeders: feed on plankton or detritus
suspended in the water. e.g. barnacles, sponges,
mussels, clams
• Grazers: herbivores (eat seaweed) e.g. limpets,
abalone, sea urchins
• Predators: e.g. fish, nudibranchs, octopus
• Scavengers: feed on dead organic matter, detritus
and larger leftovers, e.g. crabs, isopods
Modes of Feeding
Barnacle
Suspension feeder
Crab
scavenger
Sea cucumber
Deposit feeder
Sea urchin
grazer
Modes of Reproduction
• Fission: Splitting in half, forming 2 clones of equal size,
asexual, e.g. sea anemone
• Budding: small growths the “break off” and become
individuals, asexual, e.g. sponges
• Spawning: release gametes into water, more offspring, but
less survival e.g. mussels, sea urchins, some fish
• Internal fertilization: sperm transfer to female, e.g. snails,
squid, octopus, sharks
• Hermaphroditism: an individual is both male and female
e.g. sea anemone, sea slugs (nudibranch)
• Egg Laying: can occur before or after fertilization
• Sex Changes: Some fish, anemone, slipper snail
• Brooding: parental care, fewer offspring but greater
survival, e.g. slipper snails, anemone, some sea stars,
some fish
Brooding: anemone
Egg laying: nudibranch
Spawning: sponge
Fission: anemone
p. 217-222
Rocky Shores
• The “Intertidal Zone” is the shore
area between the highest and
lowest tides.
• To live in a Rocky Shore
organisms must have
adaptations that allow them to
prevent:
1) Removal from the substrate by
waves (e.g. byssal threads in
mussels, holdfasts in algae)
2) Physical Damage from Waves
(e.g. limpets have thick, low
profile shells and dig pits in the
rocks)
3) Dessication (run and hide or
“clam up”)
4) Temperature extreme fatality
5) Salinity change fatality
p.223-225
Rocky Shore
• Rocky Shores are heavily
populated, and the limiting
resource is not food, but
Space. Food is abundant,
but space is limited. There
is great competition for
space, so dispersal and
quick colonization is
important. Often plants
and animals attach to
other plants and animals.
• The Rocky Shore is
characterized by great
diversity, but low
abundance.
Vertical Zonation of Rocky Shore
• Each creature living in the
Rocky Shore has a different
tolerance for emersion and
immersion and are
therefore only found within
a particular vertical range,
resulting in a banding
pattern called vertical
zonation. These zones are
very obvious on steep
slopes and less so on
gradual slopes.
p.225-226, 230
Vertical Zonation of Rocky Shore
• The upper limit of a zone for a creature is set by physical
factors (emersion time, wave action) e.g. if there is gentle wave
action, rocks will have more algae. If there is heavy wave
action, rocks will have more barnacles, mussels and limpets.
• The lower limit of a zone for a creature is set by biological
factors (competition, predation)
• E.g. Ke ystone Predator: a predator that is important in
maintaining the structure of the community …in a rocky shore
sea stars are a keystone predator that limits the mussel zone.
Upper Intertidal Zone
• Seldom under water…”Splash zone”
• Green algae, lichen, periwinkle snails,
limpets
p.226-233
Middle Intertidal Zone
• Regularly uncovered and covered with water
• Acorn barnacles, mussels, rockweed (brown)
Lower Intertidal Zone
• Covered by water most of the time
• Dominated by seaweeds of all types and many small
creatures
• Laminaria, Egregia, sea anemones, small fish, Sea
slugs
p.234-239
Sandy Shore
• Soft bottoms are unstable and shift in response to
waves, tides and currents. So organisms do not have
solid places to attach.
• Few primary producers live here and the water motion
is great, so the main food is suspended in the water:
plankton and detritus.
• Burrowers and suspension feeders: clams, sand
crabs, polychaete worms,
• Predators: sea birds, surf perch, swimming crab
• Upper beach: amphipods, isopods
• The Sandy Shore has low diversity, but great
abundance.
Sandy Shore
Salt Marsh or Estuary
• Fresh water rivers and salt water tides
meet here.
• Consists of mud flats and grass marshes
• The margins are dominated by grasses:
Cordgrass & Pickleweed
• Mudflats have much bacteria, worms,
crabs, snails, fish, sea birds
• Estuaries are fish nurseries for many
species
Salt Marsh or Estuary
p.260-266
Subtidal Soft Bottom
• The sandy/muddy bottom which is always
underwater and on the continental shelf
• Low diversity but great abundance
• Epifauna live on the sand, Infauna live in the sand
• Closer to shore is sand and suspension feeders;
farther from shore are finer muds and deposit
feeders.
• Detritus is the main food.
• Large populations of deposit feeders: worms, heart
urchins, sand dollars, brittle stars, sea cucumbers
• Suspension feeders: many species of clams
• Predators: moon snails, sea stars, crabs, octopus,
rays and skates, halibut, angel shark, gray whale
Subtidal Soft Bottom
p.270-274
Kelp Forest
• Restricted to cold water with much water
movement over rocky bottoms.
• Kelp can grow 20 inches per day
• Layers include the canopy, understory and
bottom… all of which have great diversity of
species
• Kelp grazers: sea urchins, abalone, sea hares
• Fish: Sheephead, rockfish,
• Keystone species: sea otter, sea urchin, kelp
Kelp Forest
Coral Reef Types
• Fringing Reef: develops close to shore
• Barrier Reef: develops far from shore with a lagoon in
between as volcano subsides
• Atoll: a ring around a central lagoon after volcano has
sunk.
p.284-290
Corals
• Corals are like miniature sea
anemones that grow in
colonies and make the rock
they live in, building cup-like
holes
• Individuals are called polyps.
• Most contain zooxanthellae
algae in a symbiotic
relationship where the coral
provide a home while the
algae provides food by
photosynthesis. Coral also
eat.
p.276-280
Coral Reef Residents
• The organisms that make up the main
structure of a coral reef are stony
corals, soft corals and sponges
• Coral reefs need intense light and warm
temperatures
p.280-283,
292-298
Coral Reef Residents