1. Unit 3: Coastal Communities

2. 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.

3. 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.

4. Phylum Chlorophyta: Green Algae
Chlorophyll = green
10% marine, upper intertidal
Examples:
Ulva (sea lettuce)
Cladophora
Codium (dead man’s fingers)

5. Phylum Phaeophyta: Brown Algae
Largest and most complex
Chlorophyll masked by fucoxanthin
Examples:
Fucus (Rockweed)
Macrocystis (Kelp)
Laminaria (Oarweed)

6. Phylum Rhodophyta: Red Algae
Chlorophyll masked by phycoerythrin
Subtidal to 200m
Examples:
Gigartina (Turkish Towel)
Corraline Algae
Porphyra (Nori)

7. 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

8. 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.

9. 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

10. 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.

11. 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

12. Modes of Feeding Crab scavenger Barnacle Suspension feeder
Sea cucumber
Deposit feeder
Sea urchin
grazer

13. 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

14. Brooding: anemone
Egg laying: nudibranch
Spawning: sponge
Fission: anemone

15. Rocky Shores p
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

16. Rocky Shore p
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.

17. 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 , 230

18. 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. Keystone 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.

19. Upper Intertidal Zone Seldom under water…”Splash zone”
Green algae, lichen, periwinkle snails, limpets p

20. Middle Intertidal Zone
Regularly uncovered and covered with water
Acorn barnacles, mussels, rockweed (brown)

21. 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

22. p
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.

23. Sandy Shore

24. 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

25. Salt Marsh or Estuary

26. p
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

27. Subtidal Soft Bottom

28. p
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

29. Kelp Forest

30. 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

31. 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

32. 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 ,

33. Coral Reef Residents