Ecology - Chapter 3

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Hydrologic Cycle

- Over 71% of the Earth’s surface is covered by water:

- Oceans contain 97% of the total volume.

- Polar ice caps and glaciers contain 2% of the total volume.

- Freshwater in lakes, rivers, and groundwater makes up less than 1% of the total volume.


Distribution of water is not static

Heat -> Evaporation -> Clouds -> Precipitation


Precipitation results in surface water:

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- Oceans, lakes, ponds, rivers, streams etc

- Consumed by organisms

- Some water will end up below Earth’s surface, which is called groundwater


Turnover Time

storage volume divided by annual inflow or outflow volume, assuming steady-state, is the time required for the entire volume of a reservoir to be renewed.

In other words, the time it takes to replace the entire storage in a reservoir.


Turn over time for bodies of water

1. Water in Atmos - 9 Days

2. River (relative) - 12-20 Days

3. Lakes - Days to Centuries

4. Oceans - 3,100 years


Oceans - Geography

- planet has one single large ocean covering 360 million km^2

- separated into three major ocean basins each with a smaller number of seas along the margin


Pacific Ocean

- the largest ocean basin with a total area of nearly 180 million km^2.

- the average depth of the pacific is 4000m with the deepest point at over 10,000 m in the Marianas Trench ( would engulf Mt. Everst with 2km to spare)


Seas of the Pacific Ocean

Gulf of California, Gulf of Alaska, Bering Sea, Sea of Okhotsk, Sea of Japan, China Sea, Tasman Sea, Coral Sea


Atlantic Ocean

- second largest with total area over 106 million km2

- average depth 3900m


Seas of the Atlantic

Mediterranean, black Sea, North Sea, Baltic Sea, Gulf of Mexico, Caribbean Sea


Indian Ocean

- smallest basin with an area of just under 75 million km2

- average depth of the Indian Ocean is 3900m


Seas of the Indian

Bay of Bengal, Arabian Sea, Persian Gulf, Red Sea



Physical Conditions: Temperature

- sunlight increases velocity of water (its kinetic state)

* rapid motion decreases density (the molecules spread out), thus warm water floats on top of cooler water



Physical Conditions: Temperature


layer of water through which temperature changes rapidly with depth

- creates thermal stratification



Physical Conditions: Light

- Approx 80% of solar energy striking the ocean is absorbed in the first 10 m.

- UV and infrared is also absorbed in the first few metres

- Very little, if any light penetrates past 600 m (even in the clearest water.

** Leaves approximately 3,400 m of deep dark water with only light produced by bioluminescence.


Shallow waters have much more vibrant colors than deeper waters because

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light is absorbed differentially



Physical Conditions: Light Levels

Littoral Zone

(intertidal zone)

shallow shoreline



Physical Conditions: Light Levels

Neritic Zone

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Coast to margin of the continental shelf


Marine Environments

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The Open Ocean is divided up into different zones



Open water habitat occuring off the bottom of the ocean



Habitat occurring on the bottom of the ocean


Oceans - Chemical Conditions: Salinity

- In the open ocean, salinity varies from about 34 ppt to 36.5 ppt, i.e., 34-36.5 g of salt per 1000 g of solution.

- Lowest salinity occurs near equator where precipitation exceeds evaporation and above 40o, particularly in the summer when ice melts.

- Highest salinity occurs in subtropics (20o-30o North/South latitude) where evaporation exceeds precipitation.

- Although the percentage of salinity can change from ocean to ocean and region to region, the relative proportions of the predominant ions (sodium, magnesium and chloride) remain constant.


Salinity Units

- additionally salt concentration has been given as parts per thousand (ppt, which is written shorthand as o/oo)

- psu is another

1 psu = 1ppt = 1%


Oceans - Chemical Conditions: Oxygen

-Typically, O2 concentration is highest near the ocean surface and decreases with depth to about 1000 m.

- Concentration increases below 1000 m due to low metabolism, cold water, and thermohaline circulation.


Oceans - Biology

- Photosynthetic organisms are limited to upper epipelagic zone ( i.e., the euphotic zone). Remember the epipelagic is 0-200 m deep, but not all of that will necessarily have enough light to support photosynthesis.

- Photosynthetic organisms include plants, macroscopic algae (these usually occur in the intertidal or neritic zones) and phytoplankton

** Phytoplankton microscopic photosynthetic organisms that drift with current of an ocean or lake

** Due to its size, oceans contribute ~50-80% of total photosynthesis in the biosphere.

** Zooplankton animals (often microscopic in size) that drift in surface waters of an ocean or lake.


Compensation Depth

generally corresponds to about 1% of surface light level


Aphotic Zone

enter as you descend through the epipelagic

it is pitch black

the clearest ocean

below 600m


Marine Snow

organic matter fixed in the euphotic zone that drifts down into deeper layers of the ocean as organisms produce waste products and or die



also a source of energy

- the synthesis of organic compounds by prokaryotes using energy derived from reactions involving inorganic chemicals, occurs near undersea hot springs.



Physical Conditions: Water Movements

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–Wind-driven surface currents across open ocean create gyres that move right in the Northern Hemisphere and left in the Southern Hemisphere due to the Coriolis effect.


Ekman Spiral

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a structure of currents or winds near a horizontal boundary in which the flow direction rotates as one moves away from the boundary.


Wave Formation - Factors that Influence Wave Heigh

Fetch, Windspeed, Duration time of wind, depth of water



distance across which the wind blows


Flood Tide or Flood current

tide rises for several hours


Slack Tide

a period of high water


Ebb tide

tide begins to fall

.. after which the tide is again slack


Semidiurnal tides

two periods of low and high tides daily


dinural tides

single low and high tide each day



when the sun, moon and earth form a line

the grave pull of the sun reinforces that of the moon and the tidal range is maximal

(spring tide)


Spring tides

Occur during full or new moons—which occur when the Earth, sun, and moon are nearly in alignment—average tidal ranges are slightly larger.


Perigean - Spring Tide: New Moon

(or supermoons)

moon closest to earth in monthly orbit (perigee)

moon in alignment with sun

moon between earth and sun


Perigean - Spring Tide: Full Moon

moon closest to earth in monthly orbit (perigee)

moon in alignment with sun

earth between moon and sun


Tidal Bore

a large wave caused by the funneling of a flood tide as it enters a long, narrow, shallow inlet.


Neap tide

when the sun, earth and moon are at a 90o angle, the grave forces of the sun partially cancel those of the moon and the tidal range is minimal


Gross Primary Production (GPP)

The synthesis of organic materials from inorganic substances.

i.e., the total amount of energy fixed by primary producers

g C/m2/yr


Net Primary Production (NPP)

NPP = GPP - Respiration by Prim Producers

i.e., net primary production is the amount of energy available to consumers in an ecosystem.


Endemic and Not Endemic

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Life in Shallow Marine Waters: Coral Reefs

- are generally found between 30 degrees north latitude to 30 degrees south.

- Corals only occupy about 1% of the ocean floor.

- However, an estimated 25% of marine life call coral reefs home.

- That is why they are often called the rainforest of the sea.


The First to place categories on coral reefs

Charles Darwin


Fringing Reef

This type of reef grows seaward directly from the shore

form borders along the shoreline and surrounding islands.


Barrier Reefs

- they also border a shoreline; however, instead of growing directly out from the shore, they are separated from land by an expanse of water.

- This creates a lagoon of open, often deep water between the reef and the shore.

- When a fringing reef continues to grow upward from a volcanic island that has sunk entirely below sea level, an atoll is formed. Atolls are usually circular or oval in shape, with an open lagoon in the center.


Patch Reefs

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- are small, isolated reefs that grow up from the open bottom of the island platform or continental shelf.

- They usually occur between fringing reefs and barrier reefs. They vary greatly in size, and they rarely reach the surface of the water.

–The Great Barrier Reef off the northeast coast of Australia stretches for over 2000 km. It is visible from space!


Reef building corals are limited to the

photic zone, where light penetrates


Sunlight is important because

most reef building corals harbor mutualistic dinoflagellates (called zooxanthellae) that contribute photosynthate to the corals

– Nutrient levels of the surrounding water are low, so zooxanthellae photosynthesis plays an important role in augmenting coral energy.

– If nutrient levels increase, phytoplankton in the water column begin to bloom.

- This causes water clarity to decrease, blocking sunlight from the coral’s zooxanthellae and smothering the reef.


Corals need and prefer

- warm water of at least 18-20 C but less than 29 C. Above and below those temperatures is generally lethal.

- salinity levels between 32 and 40 ppt. If salinity drops too low (e.g., due to lots of rainfall and subsequent runoff of freshwater from land), it can kill coral.


Shallow - Water Environments: Kelp Forests

- are found growing on hard substrates in cool, clear, nutrient rich, temperate waters (~30 to 50o N/S) often on rocky shorelines

- In some areas, kelp can grow 25 to 40 m, forming what appear to be underwater forests.

- provides home for many invertebrates, fish, birds and marine mammals such as seals

- upwelling brings cold nutrient rich water to the surface


Which of the following reservoirs of the hydrological cycle has the shortest turnover time?



Which wave lengths of visible light are most easily absorbed by water


Answer: Red


This part of the ocean extends from the coast to the margin of the continental shelf



The __ __ generally corresponds to about 1% of the surface light level.

Compensation Depth


Wind Driven surface currents across open ocean creat _ that moves to the right in the northern hemisphere and left in the southern hemisphere



The high tide today is at 3.7ft (A)

Two weeks later it is at 2.5 ft. (B)

Two weeks after it is at 3.7 ft (C)

Which of these is full or new moon?

A and C


Kelp Forests - Conditions

-beds grow in temperate, rocky coastal waters.

- kelp grow in shallow coastal water from 2-30 m deep.

- Kelp beds require cool (5-20 oC) nutrient rich waters.

–The cool nutrient rich water is often maintained by coastal upwelling.

- Kelp beds are tolerant of freshwater runoff, and resultant lower salinity.

- The water of a healthy kelp forest is well oxygenated.


Kelp Forests - Locations

along the western coasts of North and South America, northeastern Canada, western Europe, South Africa, New Zealand, Japan and eastern Russia.


Intertidal Zone (Littoral Zone)

Life Between High and Low Tides


anywhere ocean meets land

Environment can vary greatly depending on if the shore is protected (for instance in a cove of a bay or exposed to the full force of ocean waves) or if it is rocky or sandy.


Intertidal Zone (Littoral Zone)

Life Between High and Low Tides


Supratidal Fringe, Upper/Middle/Lower Intertidal, Subtidal


Supratidal Fringe

Seldom covered by high tide (splash zone).


Upper Intertidal

–Covered only during highest tides.


Middle Intertidal

Covered and uncovered during average tidal changes.


Lower Intertidal

Uncovered during lowest tides.



Covered by water even during lowest tides.



- In tropical regions, marine organisms exposed to the air during low tides can be exposed to temperatures above 40oC, whereas in polar regimes temperatures can drop to well below 0oC.

- The most extreme variation is in temperate regions, where summers can be hot, and winters very cold.



- This can vary widely. Rainwater can result in virtually freshwater conditions during low tide. However, during the heat of the summer, evaporating water from tide pools can result in hypersaline conditions.


Water movement

Water movement is due to tides

In some regions of the world, tide variation may only be a few centimeters.

In other areas, the shape of the coastline can funnel tidal water into a bay, resulting in huge tidal fluctuations.

The greatest tidal fluctuation on Earth is the Bay of Fundy in northeastern Canada.



At low tide organisms are exposed to the full intensity of the sun.

During high tide light levels can drop dramatically due to high turbidity



the measure of relative clarity of water



Because of rapid water movement, the shallow depth and repeated exposure to air, oxygen is generally not a limiting factor to growth.

However, protected shorelines of sheltered bays can have a build up of muddy sediments with weak circulation. This can cause oxygen levels to drop.


Intertidal Zone (Littoral Zone)

Life Between High and Low Tides

Biology: Zonation of Species (Rocky)

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Vertical zonation of species is most obvious in rocky intertidal shorelines, because algae and animals cling to the rocky surface. Zonation is a function of the species ability to survive exposure to air.


Intertidal Zone (Littoral Zone)

Life Between High and Low Tides

Biology: Zonation of Species (Sandy)

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Vertical zonation of species in a sandy shoreline is not as obvious, because most of the animals that live here burrow in the sand. Additionally, without a hard substrate, multicellular algae can’t live here


Hydrothermal Vents

- contains an assemblage of animals associated with these deep-sea

- spew out hot water up to 400C and rich in hydrogen sulfide


Open Ocean: Hydrothermal Vents

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located worldwide along mid-oceanic ridges such as the East Pacific Rise and the Mid-Atlantic ridge, at an average depth of 2,100 m (7,000 feet).


Shallow - Water Environment: Sea Grasses

- found on the bottom of protected bays and other shallow coastal waters with clear water and soft, sandy or muddy substrates

** They are often present in areas where kelp are absent (kelp generally likes rocky substrates) and occur in both warm and cool waters worldwide.

** In tropical and subtropical waters, sea grass beds are often found in the lagoons between barrier reefs and the shoreline. They are often used as nurseries for juvenile reef fish.

** Their roots help to keep sediments in place preventing coastal erosion


Sea Grasses

- Large mammals such as manatees graze on sea grasses as do green turtles.

- Many smaller animals settle on the grass blades and filter feed.

- Sea grass beds remove nitrogen and carbon dioxide from the water.



regions where rivers meet the sea and fresh and saltwater mix. Thus estuaries mark the boundary between freshwater and saltwater habitats.

Freshwater is less dense than saltwater. Thus when fresh river water flows into the ocean, it stratifies into two layers forming what is called a salt wedge.

Notice that the bottom of a river near its mouth (where the river meets the sea) has dense saltwater, which is why marine organisms can swim upstream into what may otherwise seem to be a freshwater environment.



boundary between fresh and saltwater



both halocline (salinity gradients) and the thermocline (temperature gradients)



nutrient enrichment of an ecosystem, generally resulting in increased primary production and reduced biodiveristy—in estuaries leads to coastal “dead zones”


Mangrove Forests and Salt Marshes


- develop in protected intertidal areas including coves, bays and estuaries, where wave action is limited, and fine sand and mud can accumulate.

- commonly associated with estuaries (but are not necessarily so)

– Plant roots slow down tidal flow so that its sediment is deposited, not re-suspended as the tide ebbs– this reduces erosion.

– Mangrove forests are located along the world’s tropical coastlines between about 25°N and 25°S.

– Beyond these latitudes, salt marshes are found. Some exceptions occur where warm water extends beyond these limits, as in Japan and Bermuda (remember that gyres can bring tropical water into temperate regions).


Types of Mangroves

Red, black, White, Buttonwood


Adaptations of Mangroves

Prop roots help red mangroves remain stable in shifting substrates

aerial roots improve oxygen transport to roots in black mangroves


Vertical Zonation in mangroves causes

The most salt tolerant species live closest to the shore, where they spend more time saturated by salt water.

–A variety of insect herbivores feed on both salt marsh and mangrove vegetation but the saline environment restricts many large grazers.


Freshwater Environments

- includes lakes, rivers, and freshwater wetlands (swamps that have woody trees and marshes, which do not have trees but have grasses and other herbaceous plants)



Standing water habitats, such as lakes



Running water habitats, such as rivers



- Most found in mountainous areas, areas of tectonic activity, or areas of recent glaciation.

- Lakes are generally regarded as being greater than 2 ha (1 ha = 2.47 acres) in area and ponds are less than 2 ha.

–But this is really an arbitrary designationA

- lthough lakes are bigger than ponds, it is estimated that there are nine times as many ponds as lakes.


Lakes - North America

Great Bear Lake, Great Slave Lake, Lake Althabasca, Great Salt Lake, Lake Winnipeg, Great Lakers


Lakes - South America

Lake Titicaca


Lakes - Africa

Lake Chad, Tanganyika, nyasa, Victoria, Turkana, Tana


Lakes - Europe

Lake Varnern, Ladoga


Lakes - Asia

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Capsian Sea, Lake Balkash, Aral Sea, Lake Baikal


Dissolved Oxygen (DO)

•the amount of molecular oxygen which occurs between water molecules and which supports aquatic life.


Amont of DO

– Oxygen enters the water directly via diffusion from the atmosphere, from aquatic plants or algae which release it via photosynthesis, or via waterfalls and water tumbling over rocks which traps air.

–Lotic water, such as fast flowing streams, usually contains higher levels of DO than stagnant lentic water.

–Temperature affects dissolved oxygen; cold water can hold greater amounts of DO than warm water.

- Large amounts of dead organic matter can result in very low DO, too low to support fish populations.



Areas with dissolved oxygen of <0.2 ppm



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DO of < 2.0 ppm

- –Many adult fish species can survive in 3.0 – 5.0 ppm DO, but spawning and growth of young fish may require 6.0 ppm and above.



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Lakes - Physical Conditions


Lake watercolor, and how deep light penetrates the water column will depend on light absorption and largely due to biological activity.


Lakes - Physical Conditions


–Lakes become thermally stratified as they warm. This can create thermoclines, which may be seasonal.


Lakes - Physical Conditions

Water Movement

Wind-driven mixing of the water column is ecologically important to suspend nutrients into the water column


Lakes - Structure

Littoral zone

Nearshore shallows


Lakes - Structure

Limnetic zone

Open Lakes


Lakes - Structure

Vertical Zonation: Epilimnion

Warm surface layers.


Lakes - Structure

Vertical Zonation: Metalimnion

•Temperature changes with depth (location of the thermocline).


Lakes - Structure

Vertical Zonation: Hypolimnion

Deepest parts of the lake

water is cold and can be dark .


Spring Overturn

In the spring, ice melts and spring storms mix the water layers, creating uniform conditions of temperature.

When the ice melts in the spring, the cold water sinks and mixes the lake (with the help of winds from spring storms. Notice that the overturn creates uniform temperature and oxygen concentration from the surface to the bottom of the lake.


Three Layers present in Temperate Lakes

1.An upper layer, called the epilimnion, is warmed by the sun and mixed well by the wind.

2.Below this lies a transition zone known as the metalimnion, which is the location of the thermocline.

3.Lowest still is the hypolimnion, a cool layer too far below the surface to receive much light or to be much warmed.


Seasonal Affects on Oxygen Conc


- the warmest water occurs at the surface, and water temperature decreases with depth.


Seasonal Affects on Oxygen Conc


- the surface water begins to cool, until eventually the entire water column reaches an equilibrium temperature.

•The result is a fall turnover, analogous to that of what occurs in the spring. So like the spring, not only are temperatures constant from the surface to the bottom, due to the turnover, so are oxygen concentrations.


Seasonal Affects on Oxygen Conc


- if there is little or no snow cover to block sunlight, phytoplankton and some macrophytes may continue to photosynthesize just beneath the ice, resulting in a small increase in DO just below the ice.



Low biological primary production, although often well oxygenated even at depth, and are generally deeper than a eutrophic lake.



: High biological primary production, but may be depleted of oxygen, particularly at depth, and are generally shallower than an oligotrophic lake.


Oligrotrophic Conditions

Oligotrophic lakes generally have low primary productivity. This is because the nutrient levels are low (especially phosphate and nitrate)

Oligotrophic lakes are often very deep and relatively young geologically.

Young lakes have not had a chance to accumulate as many dissolved nutrients as have older ones.

- lakes are relatively clear, and their compensation depth may lie below the thermocline.

–Low nutrient concentrations keep the algae and rooted plants in the epilimnion sparse, and little debris (equivalent to marine snow) rains down upon the inhabitants of the hypolimnion.

–As a result, the hypolimnion is clear, cold and well oxygenated.

–Lake trout, do well in oligotrophic lakes as they require cold, well-oxygenated water and primarily live in the hypolimnion of oligotrophic lakes.


Rivers - North America

Yukon, Mackenzie, Missouri, St. Lawrence, Columbia, Coloroda, Rio Grande, Mississipi


Rivers - South America

Orinoco, Amazon, La Plata


Rivers - Africa

Nile, Niger, Congo, Zambezi, Orange


Rivers - Australia

Murray - Darling


Rivers - Asia

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Yensey, Ob, Volga, Amu Darya, Lena, Amur, Hyang He, Yangtze, Xi, Meckong, Ganges, Indus


Riparian Zone

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the transition zone between the aquatic environment of a river or stream and the upland terrestrial environment - often subject to flooding and an elevated ground water table


Stream Order - Changes in downstream designations down

First Order – Headwater (where the stream/river begins)

Second Order - Joining of two first order streams.

Third Order - Joining of two second order.

Fourth Order – Major river systems



- Where rivers flow into the sea, estuaries form.

- In this area, sediments that were suspended in the river as it erodes material over the course of its meanderings, begins to settle out. This sedimentary material is called alluvium—a general term for clay, silt, sand, gravel or deposited a stream or other body of running water.

- When an exceptionally large river meets the sea (or a large lake), the river may take on a braided appearance forming a delta--a nearly flat coastal region composed of alluvial deposits, creating a triangular or fan shaped plain as the river separates into many smaller rivers before it discharges into a lake or ocean.


Rivers - Conditions

Oxygen levels and water clarity are greater in the headwaters than in the lower reaches of rivers where more alluvium is deposited.

Nutrient levels and temperatures are generally lower in headwaters.



flat area of land adjacent to a river which can experience occasional flooding.


Rivers and Streams - Physical Conditions


– How much light shines on the surface often depends on riparian vegetation—particularly in headwaters where streams are smaller. Shading decreases downstream as rivers widen (first order streams combining to form second order streams etc.)

– How far light penetrates the water column depends on amount of suspended particles—rivers are constantly eroding the surrounding landscape.


Rivers and Streams - Physical Conditions


- Closely tracks air temperature (although it will never reach the extremes of air temperature—remember waters high specific heat; also ice can form over rivers).


River Discharge

The amount of water carried by rivers is


temperate river system with moderate, relatively constant rain year-round, and thus

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a relative constant discharge.


semi arid river system with highly periodic heavy rains, and lower amounts of seasonal rains punctuated by drought.

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extreme variation in rainfall results in extreme variation in discharge.


Rivers and Streams

Chemical Conditions


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Reflects prevailing climate in the region. Where annual rainfall is high (such as in the tropics) soils have been largely leached of soluble minerals.

In desert regions, where rainfall is much lower, and water that does fall evaporates rapidly, salinity levels can be much higher.


Oxygen in Rivers

Oxygen levels in rivers are usually inversely correlated with temperature—highest in cold water rivers and lower in warm water rivers.

- The continual mixing of water due to its flow generally mean that oxygen is not a limiting factor to growth in river systems.

However, if rivers and streams are receiving large amounts of organic wastes from cities, industries, agriculture, etc., high levels of cellular respiration by decomposers (e.g., bacteria and fungi) results in a high BOD-biochemical oxygen demand.

BOD is a measure of organic pollution that is defined as the amount of dissolved oxygen required by microbes (bacteria and fungi) to decompose the organic matter in a water sample. Used a measure of organic pollution.


Rivers and Streams - Biology

•As with terrestrial tropical biomes, there is a lot more diversity in tropical rivers than in temperate rivers.

–As an example, the Mississippi is considered to have one of the most divers temperate fish assemblages, with about 300 species.

–The tropical Congo River has 669 fish species, with 558 being endemic.

–But the mother of all fish diversity rivers is the Amazon, which contains over 2,000 species, about 10% of all known freshwater species of fish on earth!



they live on or in the river’s bottom sediments.



(spaces between) the grains of sand and sediments

a large diversity of invertebrates that can live deep within the rivers sediments

–These species live in the hyporheic and phreatic zones, and can be collected via pumps along the rivers edge, or from wells dug even kilometers from a river.


River Continuum Concept

plant matter is a significant contributor to organic matter in rivers.

predicts different species will be found in different parts of the river. What species are found in what parts of the river depend on water temperature, oxygen concentration and the amount of CPOM or FPOM.



When the matter enters the river first



invertebrates that feed on CPOM



fungus and bacterial feed on the material to conver to this, making it more nutrituous for invertebrates



invertebrates that feed on fine particular organic matter (FPOM)



are underground layers of water-bearing (permeable) rock (i.e, the phreatic zone). Where groundwater flows out of the ground to the surface it is called a spring.


According to the article, "What is...", by what percent has the ocean's surface water acidity increased since the Industrial Revolution?



Kelp factors prefer which of the following

Hard (rocky) substrates

nutrient rich water

cold water 5-20oC


Which of the following zones of the intertidal would you predict would have the least diversity of marine organisms?



Which of the following is NOT true about sea grasses?

Their holdfass are a food resource for sea urchins


Which of the following is true about mangroves and salt marshes?

both exhibit vertical zonation of species based on daily tide fluctuations

spartina altiniflora and the red mangroves have similar ecological niches


Areas of dissolved oxygen of <0.2ppm are called



Using a specialized piece of equipment called a snade, water oxygen levels are measures at 5.24 mg/L at 20oC. There is a max of 9.07 ppm oxygen at that temperatures. What is the approx DO% sat?

58% (TABLE)


At what temp is freshwater most dense



in a temperate lake the metalimnion is most likely to exist during

the summer


a deep lake in a mountanious region, which has crystal clear blue water is most likely


going to have a compensation depth below the thermocline


Which fo the following is not true about eutrophication?

it is not natural but caused only by human nutrients inputs


the transition zone between the aquatic environment of a river and the terrestrial environment called

Riparian Zone


In what type of terrestrial biome would you expect rivers to have the greatest salinity levels



Whole leaves and other relatively large parts of plant material are consumed by invertebrate _ in freshwater habitats such as rivers



According to the River continuum concept where would you expect to find the highest biomass of types (shredders)

Small headwater streams


dr sawicki studies

prokaryotic mats, crustaceans, amphipods, taxonomy, phylogenetics


you have an opportunity... you are floating along a wall that drops vertically from the surface to 100m. At 20m you notice that there is red algae at that depth and shallower, but not algae any deeper. What is true about depth

At a depth 20m, cellular respiration of primary producers equals their photosynthetic output


Examine the max DO

Using the data in the table what will you expect the DO percent to be for a body of water with 1.9 ppm at 30oC


b/c 1.9/7.54 = 25%


relative to the oxygen level of the wat... How would this water be described



Ocean salinity varies from about 34ppt to 36.5 ppt. The higher salinity levels (around 36ppt) would likely occur

around 30 degrees N/s lattitude


Below the hyporheic zone of a river is the _ zone - is is also called ground water

Phreatic Zone


Consider the following Aquatic regions:

A. Water surrounding a coral reef

b. sublittoral zone in coastal regions of the artic sea

c. euphotic zone of the central north pacific ocean

d. stuary,.

e. both a and b




A) neap tide

b) slack tide

c) perigee

d) syzgy

e) ebb tide

f) flood tide

Which of these apply to a supertide ( a high tide that is at least a few inches higher than normal)

C and F

perigee and flood tide


Examine the image which applys to the phenomenon

Ekman Spiral (search this up there)


consider the following aquatic regions

a) mouth of a large river, b) sublittoral zone in coastal regions of the artic sea c) euphotic zone d) esurary e) both a and D

which would you predict would have the greatest seasonal variation in primary productivity

B sublittoral zone in coastal regions of the artic sea


Flora and Fauna that live on or in the bottom sediments of a river live in the:

benthic zone