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 Crab scavenger Barnacle Suspension feeder 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

Rocky Shores p. 217-222 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

Rocky Shore p.223-225 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. 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.

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