CHAPTER 4 SECTION 4 SC B-6 STUDENTS WILL DEMONSTRATE AN UNDERSTANDING OF THE INTERRELATIONSHIPS AMONG ORGANISMS & THE BIOTIC & ABIOTIC COMPONENTS OF THEIR ENVIRONMENT AQUATIC BIOMES

Aquatic Biomes charaterized primarily by their physical environment rather than be climate often layered with regard to  light penetration  temperature  community structure

Zonation in Aquatic Biomes light absorbed by water itself + photosynthetic organisms so…light intensity decreases rapidly with depth Photic Zone: sufficient light for photosynthesis Aphotic Zone: little light penetrates Pelagic Zone = photic zone + aphotic zone

Zonation in Aquatic Biomes Abyssal Zone:  2,000 – 6,000 m deep Benthic Zone:  the bottom of all aquatic biomes, shallow or deep Benthos:  communities of organisms that live in sand & sediments of the benthic zone

More Definitions Detritus:  dead organic material that “rains” down from photic zone; food source for benthos Thermocline:  narrow layer of water where there is an abrupt temperature change  separates the more uniformly warm upper layer from the uniformly cold deeper water  many temperate lakes undergo a semiannual mixing of their water

Lakes lake environment generally classified on basis of 3 physical criteria: 1. light penetration  photic / aphotic 2. distance from shore / depth of water  littoral / limnetic 3. open water / bottom  pelagic / benthic

Lakes standing bodies of water range from ponds a few square meters in area to lakes covering thousands of square kilometers

Lakes: Oligotrophic

Lakes: Eutrophic

Lakes: Photosynthetic Organisms Littoral Zone:  shallow, well-lit waters close to shore  rooted & floating aquatic plants Limnetic Zone:  waters too deep to support rooted plants  phytoplankton, including cyanobacteria

Phytoplankton

Lakes: Heterotrophs Limnetic Zone:  small, drifting heterotrophs or zooplankton (graze on phytoplankton) Benthic Zone:  assorted invertebrates (species depends on O 2 content)  Fishes live in all zones that have sufficient O 2

Zooplankton

Wetlands habitat that is inundated by water (at least part of the year) & supports plants adapted to water- saturated soil due to high organic production by plants & decomposition by microbes: water & soil of wetlands periodically low in dissolved O 2 *high filter capacity: both nutrients & pollutants

Wetlands: Autotrophs among most productive biomes in world water-saturated soils great for plants  Lily pads  Cattails  Sedges  Tamaracks  Black spruce

Wetlands: Heterotrophs diverse community of invertebrates, birds, reptiles, amphibians, and mammals Herbivores:  crustaceans  aquatic insect larvae  muskrats Carnivores:  dragonflies  frogs  alligators  herons

Streams: Physical Environment most prominent characteristic: their current stratified into vertical zones

Streams: Physical Environment Headwaters:  generally cold, clear  turbulent, & swift Downstream:  generally warmer  more turbid

Estuary a transitional area between river & sea when high tide: salt water flows up estuary channel higher density sea water stays below lesser density freshwater

Estuary: Chemical Environment salinity varies from that of freshwater  sea water & with rise & fall of tides nutrients from rivers make estuaries some of most productive biomes

Estuary: Photosynthetic Organisms saltmarsh grasses & algae (including phytoplankton) are major producers

Estuary: Heterotrophs abundant #’s of worms, oysters, crabs, & many fish many invertebrates & fishes use estuaries as breeding grounds crucial feeding grounds for birds & some marine mammals

Intertidal Zones are periodically submerged & exposed by the tides, 2x daily on most marine shores upper zones exposed to air for longer periods  greater variation in temp & salinity changes in physical conditions from upper to lower zones limits the distribution of many organisms to particular strata

Intertidal Zones: Chemical Environment O 2 & nutrient levels generally high & renewed with each turn of the tides

Intertidal Zone: Photosynthetic Organisms high diversity & biomass of attached marine algae inhabit rocky intertidal zones much lower diversity & biomass in sandy intertidal zones with vigorous wave action sandy intertidal zones in protected bays or lagoons have rich beds of grass & algae

Intertidal Zone: Heterotrophs animals here have multiple structural adaptations  rocky areas: ways to attach to hard surfaces  sandy areas: many bury themselves  feed on what tides bring them

Ocean Pelagic Zone open blue waters mixed constantly by wind & ocean currents photic zone extends deeper here (water is clearer)

Oceanic Pelagic Zone: Chemical Environment O 2 levels generally high nutrient levels generally lower than in coastal waters tropical oceans: thermally stratified all year temperate & hi-latitude oceans have spring & fall turnover so generally nutrients renewed in photic zone

Oceanic Pelagic Zone: Geologic Features covers ~70% Earth’s surface average depth = 4,000 m deepest point: 10,000 m

Pelagic Zone: Photosynthetic Organisms phytoplankton (including photosynthetic bacteria) dominate due to vast area this zone covers: ~50% of all photosynthesis on Earth by them

Pelagic Zone: Heterotrophs zooplankton most abundant group in this zone graze on phytoplankton includes:  protists  worms  copepods  shrimp-like krill  jellies  small larvae of invertebrates

Pelagic Zone: Heterotrophs also include free-swimming animals:  large squid  fishes  sea turtles  marine mammals

Coral Reefs formed largely from the calcium carbonate skeletons of corals in photic zone of relatively stable tropical marine environments with high water clarity sensitive to temps 30°C found in deep seas ,500 m deep  as much diversity as shallow reef

Deep Sea Coral Reef

Shallow Coral Reef

Coral Reef: Chemical Environment require high O 2 levels

Coral Reefs: Photosynthetic Organisms unicellular algae live w/in tissues of corals in mutualistic relationship: provides corals with organic molecules diverse multicellular red & green algae growing on reef also photosynthesize

Coral Reef: Heterotrophs dominant heterotroph: corals are a diverse group of cnidarians also high diversity of fishes & invertebrates overall nearly as diverse as tropical rainforest