Lecture notes

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
  
• 
  1^st 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)