Benthos • Intertidal Zone • Muddy bottom and sandy bottom communities • Salt marshes and seagrass beds • Coral reefs • Deep ocean benthos
Intertidal Zonation Zonation is a vertical banding of the organisms living on the rocky coastline. These distinct bands occur in part from many complex physical and biological factors that effect marine organisms.
Which tidal cycle has the greatest effect on marine organisms living in the intertidal zone?
Tidal Zones on a Rocky Ocean Shore Splash Fringe Level High Tide Level Mid Tide Level Low Tide Level Low Fringe Level
Mostly shelled orgs Spray or Splash Zone High Tide Zone Middle Tide Zone Many soft bodied orgs and algae Low Tide Zone
periwinkles ulva opihi Mussels & starfish
What are some stresses that affect the organisms residing in the intertidal zone?
Biotic factors affecting organisms living in the intertidal zone: • Competition for space and food • Predation • Reproduction • Substrate settlement preference • Osmoregulation
Abiotic factors affecting organisms living in the intertidal zone: • Salinity • Temperature • Air and light exposure • Tidal flow • Waves and current action • Substrate • Wind direction and strength • Dissolved O2 • Storms • Natural Disasters
What are some adaptations to living in the intertidal zone?
Muddy bottom and sandy bottom communities • Infauna: • live within the sediment, mostly soft bottom; • mostly clams and worms (polychaetes) • burrow tubes for food scavenging and oxygen supply Orgs that live in the interstices of the sand
Muddy bottom and sandy bottom communities • 32,000 polychaetes in sand/m2 • vs • 50-500 earth worms in soil/m2 • Ecological Role: • clean sediments • aerate soil
Salt marshes • Found from the Arctic to Southern Australia • Salt marshes grow in muds and sands that are sheltered by barrier islands. • Flood and ebb currents transport saltwater, nutrients, plankton and sediments in and out of the marsh.
Zonation in Salt Marsh • Species composition and zonation governed by: • Salinity gradient: river runoff, tides • Intertidal exposure • Low species diversity Ribbed mussel Fiddler crab
Salicornia Fundulus heteroclitus Distichles spicata
Hawaiian Stilt Hawaiian Coot Found on all the main islands except Lanai Found on all the main islands
Ecological Importance: • Act as a giant sponge: • The salt marsh absorbs large volumes of water, thus minimizing the impacts of flooding and erosion and recharging groundwater. • Salt marsh plants help purify water by absorbing toxins and in some cases metabolizing them into harmless substances. • Most productive food factories on earth.
Of the original 215 million acres of wetlands in the U.S. (excluding Alaska and Hawaii) , about 106 million acres remain. distribution of wetlands in the U.S. in the 1780s distribution of wetlands in the U.S. in the 1900s
Major Causes of Wetlands Loss and Degradation Human Actions • Drainage • Dredging and stream channelization • Deposition of fill material • Diking and damming • Tilling for crop production • Levees • Logging • Mining • Construction • Runoff • Air and water pollutants • Changing nutrient levels • Releasing toxic chemicals • Introducing non-native species to the ecosystem • Grazing by domestic animals
Natural Threats • Erosion • Subsidence • Sea level rise • Droughts • Hurricanes and other storms
Five kingdom system: Monera Protista Plantae Fungi Animalia Seagrass- true vascular plants Classification Angiosperms Gymnosperms
Seagrasses • True marine angiosperm • Evolved from shoreline Lillie-like plants~100 mya • Vascular plants reinvaded the seas 3 different times (algae is nonvascular; i.e., no need for roots to transport water and nutrients) • Can grow and reproduce while completely submerged under water Distribution: 12 genera of seagrasses (5 in the high latitude and 7 in the low latitude)
Development of Seagrass Beds • Develop in: • intertidal and shallow subtidal areas on sands and muds • marine inlets and bays • lagoons and channels, which are sheltered from significant wave action
Ecological roles: • Help stabilize the sediment • Prevents resuspension of sediments in water (water is clearer) • Binds substratum, reduces turbidity, and reduces erosion • Sediment accumulation slows velocity of incoming water • Food for many organisms • Refuge for many organisms
Threats to Seagrass Beds • Seagrass productivity is highly dependent on a number of factors: • salinity • water temperature • turbidity • This ecosystem is particularly sensitive to degradation due to: • agricultural pollution-run-off of herbicides • industrial pollution • domestic pollution
Hermatypic corals: • possess zooxanthellae • are reef builders Light: Clear water Warm temperature: 18-32oC Low nutrients Low productivity in water • Ahermatypic corals: • no zooxanthellae • rely on tentacular feeding • can live in aphotic zone
Hawaiian Coral Zonation 0 m High light levels Moderate wave energy 6 m Cauliflower coral (Pocillopora meaandrina) Moderate light levels Occasional storm wave energy Lobe coral (Porites lobata) 13 m Low light levels Low wave energy Finger coral (Porites compressa) 25 m Very low light, Primarily downwelling No wave energy Plate coral (Porites rus)