CHAPTER 4 SECTION 4SC 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

deepBenthos:

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 benthosThermocline:

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 O2 content)

Fishes live in all zones that have sufficient O2

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 O2

*high filter capacity: both nutrients & pollutants

Wetlands: Autotrophs

among most productive biomes in worldwater-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 currentstratified into vertical zones

Streams: Physical Environment

Headwaters: generally cold, clear turbulent, & swift

Downstream: generally warmer more turbid

Estuary

a transitional area between river & seawhen high tide: salt water flows up estuary

channelhigher 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

O2 & 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 watersmixed constantly by wind & ocean currentsphotic zone extends deeper here (water is

clearer)

Oceanic Pelagic Zone: Chemical Environment

O2 levels generally highnutrient levels generally lower than in coastal

waterstropical oceans: thermally stratified all yeartemperate & hi-latitude oceans have spring &

fall turnover so generally nutrients renewed in photic zone

Oceanic Pelagic Zone: Geologic Features

covers ~70% Earth’s surfaceaverage depth = 4,000 mdeepest 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 phytoplanktonincludes:

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 < 18 – 20° & > 30°Cfound in deep seas 200 -1,500 m deep

as much diversity as shallow reef

Deep Sea Coral Reef

Shallow Coral Reef

Coral Reef: Chemical Environment

require high O2 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