Chapter 52 Part 3- Aquatic Biomes

•Aquatic biomes have _______ than terrestrial biomes

•They are characterized by their physical and chemical environment

less latitudinal variation

the average salt concentration in marine biomes is ___, whereas in freshwater biomes it is less than 0.1%

3%

•Freshwater biomes are strongly influenced by the soil and biotic components of the surrounding terrestrial biome

•The pattern and speed of water flow, and climate are also important factors affecting freshwater biomes

true

The photic and aphotic zones make up the _____-

pelagic zone

The upper _____ has sufficient light for photosynthesis

photic zone

the lower ______ receives little light

aphotic zone

Many aquatic biomes are stratified into zones defined by light penetration, temperature, and depth

Zonation in Aquatic Biomes

The ______ is located in the aphotic zone with a depth of 2,000–6,000 m

abyssal zone

The organic and inorganic sediment at the bottom of all aquatic zones is called the ____

benthic zone

The communities of organisms in the benthic zone are collectively called the ____

benthos

___, dead organic matter, falls from the surface and forms an important food source for the benthos

Detritus

In oceans and most lakes, a temperature boundary called the ______ separates the warm upper layer from the cold deeper water

thermocline

Many lakes undergo mixing of their waters called _____ in the spring and autumn

turnover

_____ sends oxygenated water from the surface to the bottom and nutrient-rich water from the bottom to the surface

Turnover

•In marine communities, most organisms occur in the relatively shallow photic zone

•The aphotic zone in oceans is extensive but harbors little life

true

Temperate lakes may have a ______

seasonal thermocline

tropical lowland lakes have a _______

year-round thermocline

_______ are nutrient-poor and O₂-rich with low organic content in sediments

Oligotrophic lakes

______ are nutrient-rich and high in organic content in sediments; O₂ is periodically depleted in deeper layers due to high rates of decomposition

Eutrophic lakes

____, O₂ concentration, and nutrient content vary among lakes and between seasons

Salinity

Oligotrophic lakes have ________ than eutrophic lakes

less surface area relative to depth

Rooted and floating aquatic plants live in the shallow, well-lit _____ close to shore

littoral zone

Phytoplankton inhabit the ______, where the water is too deep to support rooted plants

limnetic zone

______ are drifting heterotrophs that graze on the phytoplankton

Zooplankton

•Invertebrates live in the ____-

•Fishes live in all zones with sufficient oxygen

•Human-induced nutrient enrichment can lead to algal “blooms,” oxygen depletion, and fish kills

benthic zone

_____ are inundated by water at least some of the time and support plants adapted to water-saturated soil

Wetlands

_____ develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas

Wetlands

•Wetlands are among the most productive biomes

•Wetlands are home to diverse invertebrates and birds, as well as otters, frogs, and alligators

•Draining and filling by humans has destroyed up to 90% of wetlands in Europe

•Wetlands help to purify water and reduce flooding

true

wetland plants

•Plants include lilies, cattails, sedges, bald cypress, and black spruce

______ are dominant in swamps

Woody plants

bogs are dominated by ________

sphagnum mosses

Wetlands are home to _______

diverse invertebrates and birds, as well as otters, frogs, and alligators

______ by humans has destroyed up to 90% of wetlands in Europe

Draining and filling

Wetlands help to ________

purify water and reduce flooding

The most prominent physical characteristic of streams and rivers is ____

current

downstream rivers are _____

warm and turbid

Headwater streams are usually ______

cold, clear, swift, and turbulent

Streams and rivers are generally ____, but organic enrichment can deplete O₂ downstream

O₂-rich

Headwater streams are often ______

narrow with rocky bottoms

downstream rivers are generally _____

wide and meandering with silty bottoms

Headwater streams may be rich in ______ or rooted aquatic plants

•A diversity of fishes and invertebrates inhabit unpolluted rivers and streams

•Pollution degrades water quality and kills aquatic organisms

•Damming and flood control impair natural functioning of stream and river ecosystems

phytoplankton

An ____ is a nutrient rich and productive transition zone between a river and the sea

estuary

•Salinity varies spatially—from nearly fresh water to that of seawater—and with the changing tides

•Estuaries include a complex network of tidal channels, islands, natural levees, and mudflats

•Saltmarsh grasses and algae are the major producers

•Invertebrates, fish, waterfowl, and marine mammals are abundant

•Filling, dredging, and pollution upstream have disrupted estuaries worldwide

Estuaries

An _____ is periodically submerged and exposed by the tides

intertidal zone

•Upper intertidal zones experience longer exposure to air and greater variation in temperature and salinity

•Physical differences between intertidal zones limit the organisms to particular strata

•Oxygen and nutrient levels are generally high in intertidal zones

•Substrates are generally either rocky or sandy

•The configuration of bays or coastlines influence the magnitude of tides and mechanical forces of waves

Intertidal Zones

colder water

more oxygenated

Rocky intertidal zones support _____

attached algae

protected sandy zones support _____

seagrass and algae

The _____ is an expanse of open water covering approximately 70% of Earth’s surface

oceanic pelagic zone

•It is constantly mixed by wind-driven oceanic currents

•Oxygen levels are generally high, but nutrient concentrations are lower than coastal waters

•In temperate oceans, seasonal turnover renews nutrients in the photic zone

•Nutrient concentrations are lower in tropical oceans due to year-round thermal stratification

Oceanic Pelagic Zone

•Phytoplankton and zooplankton are the dominant organisms

•Phytoplankton in this zone account for about half of the photosynthesis on Earth

•Fish, squid, turtles, and marine mammals are common

•Overfishing, pollution, ocean acidification, and global warming have all harmed this biome

Pelagic Zones

oligotrophic

lake u would swim in

Impacts to Intertidal Zones

•Oil pollution has disrupted many intertidal areas

•Construction of rock walls and barriers to reduce erosion from waves also disrupts the intertidal zone

____ are formed from the calcium carbonate skeletons of corals

Coral reefs

deep-sea corals live at depths of ____

200–1,500 m

Shallow reef-building corals live in the photic zone in warm ____, clear water

(about 18–30ºC)

Corals require _______ and a solid substrate for attachment

high oxygen concentrations

A coral reef progresses from a ________

fringing reef to a barrier reef to a coral atoll

The________ consists of the seafloor below the surface waters of the coastal, or neritic, zone and the offshore pelagic zone

marine benthic zone

The marine benthic zone consists of the seafloor below the surface waters of the coastal, or _____, zone and the offshore pelagic zone

neritic

Organisms in the very deep benthic (abyssal) zone are adapted to _______

continuous cold (about 3°C) and very high water pressure

Deep-sea ______ are found on mid-oceanic ridges

hydrothermal vents

_________ live around the hydrothermal vents

Giant tube worms, echinoderms, and arthropods

________ are the food producers surrounding hydrothermal vents

Chemoautotrophic prokaryotes

Neritic benthic communities include______

invertebrates and fishes