LECTURE NOTES MARINE BIOLOGY (MARSC 180)
L. SNYDER
Ch. 8 Temperate Coastal Seas
 Lie between Tropics & Polar Circles (23.5º – 66.5º N. & S.)
 Intertidal Shore to Continental Shelf
Coastal Species
•Many in close association w/ seafloor
–All large marine plants & algae
•Benthic species live on or in sediment
–Impacted by sediments & seawater
•Seafloor accumulates organic detritus from photic zone
–Major food source
–Especially in aphotic zone
Benthic Animals
•Epifauna: live on sediment
•Suspension feeders live on rocks or coarse substrate to avoid clogging filters
•Infauna (macro, micro): live w/in sediment
•Swallow or displace sediments as they move, burrow
Benthic Larval Dispersal
•75% of slow-moving or attached benthos extend geographic range by broadcast
spawning (eggs & sperm)
–Larvae are temporarily planktonic (meroplankton)
–Drift w/ currents until meatmorphose into adult forms
• Many larvae don’t survive
–But, survivors extend species’ geographic range
–Increase genetic diversity
•Factors influence larval selection of suitable settling area:
•Bottom type/ texture, current speed, temp, light, chemicals from conspecific
adults Metamorphose into a juvenile form
Intertidal (Littoral) Communities
Rocky Shores
Sandy Beaches
Intertidal Zone
•Daily tidal fluctuations expose intertidal species to extremes
•Submergence (High tide): Preferred for most intertidal species (marine)
–Temp & salinity return to normal, food/nutrients & DO replenished, wastes
removed
•Emergence (Low tide): Dry terrestrial conditions, exposed to air, heat, etc.
•Intertidal species must adapt to stresses
•High tide: Crashing waves, abrasion
•Low tide: Heat, sun (UV), dryness, No O2 Cold, Freshwater (rainfall & runoff),
Predators (birds, terrestrial spp.), human trampling
Sandy Beaches
•Depositional environments
–Unconsolidated sediment (granite, shell, volcanic), & detritus
•Waves gentle enough to allow sand accumulation, but wash silt & clay away
•Longshore currents move sand along shore
–Animal populations vary seasonally
•Lower species diversity & density than rocky shores
–Unsuitable substrate for attachment
–Little algae & epifauna, mostly infauna
Beach Zonation
•Most burrow under sediments
•Increasing Diversity from splash zone toward low intertidal
Filter Feeding
•Common among beach macrofauna
EX: Sand crab (Emerita analoga)
•Uses feathery antennae to filter plankton, bacteria, & detritus from incoming water
–Protrudes above sand
CA Grunion (Leuresthes) Reproduction
•Come out of water to spawn (lay & fertilize eggs) on beach
•At night from Feb-Sep
•1st 3 hours after highest spring tides (full or new moon)
•Female digs tail in sand to lay eggs & Male deposits milt (sperm) around her
•In ~10 days babies hatch & wash out to sea at next high spring tide
•California Least Tern & Western Snowy Plover
•Ground Nesters
•Endangered species
Rocky Intertidal (Rocky Shore)
• Stressful habitat
•Wave stress, alternate dry & wet periods, sun (UV) exposure, rocks
•Clumped distribution
•Contradiction:
•Harsh physical factors: Wave stress, sun, dry
•Abundant: Food, nutrients, micro-habitats & niches
•Competition for resources:
•Affects success of species & individuals
•Vertical Zonation: species adapted to unique conditions
•Splash zone: Receive only ocean's salty spray. Flooded only by highest tides &
winter storm waves
–Upper intertidal: closest to land, mostly dry. Periwinkle snails, Barnacles
–Mid-intertidal: ½ Dry, ½ wet
Algae, limpets, crabs, mussels, purple sea urchin, Sea anemones
–Lower intertidal: furthest from shore, mostly submerged. Algae, sea stars, red
sea urchin, sea hare, sea cucumber
Intertidal Zonation: Increasing Diversity from splash zone to low intertidal
Upper Intertidal
•Wet infrequently by high tide, sea spray
•Lichens & algae store water to avoid desiccation
•Few invertebrates that tolerate dryness & temp. change
•Can seal & anchor shells to rock to seal in moisture
Middle Intertidal
•Covered & uncovered 2X/day by tides
•Species adapted to exposure to air & seawater
•Dense population = competition for substrate, water, & food
•Monocultures: Ochre seastar (Keystone sp.)
Lower Intertidal
•Species cannot tolerate air exposure
•High diversity
•Abundant algae, sea grasses
•Many soft bodied animals
•Predatory seastars move between mid & low intertidal
Oil Spills & the Intertidal
•Oil released in sea will eventually float to & rest in intertidal
•Most oil in marine environment enters via urban runoff, dumping
•Effects of spilled oil depends on type:
•Light refined petroleum (diesel & gas) – mixes in H2O column, more toxic, but
evaporates quickly & doesn’t persist in environment
•Crude – less toxic, but remains on water surface or shoreline much longer, sinks
Oil Tanker Spills
•Small portion of total marine spills
•Locally devastating, major cleanup
•U.S. Oil Pollution Act 1990 (response to Exxon Valdez): all oil-carrying vessels must
have double-hull
•Exxon still appealing $5 billion fine (17 yrs)
Oil Spills & Marine Life
•Clogs gills of fish & benthic species
•Damages digestive system
•Mammals & birds (fur, feathers) lose bouyancy & insulation
Oil Spill Cleanup
•Scrubbing w/ high pressure, hot water  damage
•Leave it alone, rely on natural processes
•Booms, shovels, buckets, absorbent materials
•Bioremediation by oil digesting bacteria
Subtidal (Sub-littoral)
•Lower intertidal merges w/ upper continental shelf
•Lower intertidal species also abundant here
–Beyond effects of tidal action
•Sediments & detritus accumulate
Kelp Forests
•Dominate subtidal areas w/ rocky outcrops
•S. California impacts:
•Overgrazed by urchins (loss of otters)
•El Nino (high temps.)
• Suspended organic material from outfalls
•Decreases photosynthesis
Sewage Treatment & Outfalls
•Primary Tr. - large solids, grease removed
•Secondary Tr. – Good bacteria eats organic solids, chlorine kills bacteria,
•chlorine removed (via chemicals)
•22% of biosolids used by farmers or compost centers
•Many chemical toxins, heavy metals, pharmaceuticals not removed & enter ocean
•Orange County Sanitation District outfall: 4 miles off coast of Huntington Beach (200
ft. deep)