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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