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EE 142 EXAM QUESTIONS AND ACCURATE
ANSWERS
identify what lentic systems are - ANSWER a) "standing water" b) lakes, ponds, lochs, pools, etc c) no dominant or unidirectional flow d) water can become stratified what types of organisms would be found in lentic systems - ANSWER i) insects (1) major part of FW systems; not in marine systems ii) crustaceans, mollusks, worms iii) vertebrates (1) amphibians, reptiles, fish, mammals iv) flowering plants (1) major component (2) more tolerant of FW than salt (3) more shallow habitats v) phytoplankton vi) algae (1) mostly green algae Explain how organisms can utilize the surface of the water in lentic systems - ANSWER a) small size b) water repellant (waxy coating; tiny hairs) c) distribute weight d) surface tension of water helps prevent sinking Describe the patterns of diversity in freshwater systems - ANSWER a) FW systems are geologically young, but species diverse b) lakes and rivers cover < 1% of earth surface
i) about 12% of all known species are FW ii) about 41% of fish species are FW c) diverse fauna with high levels of endemism i) endemic = species found only in that location Explain allopatric speciation - ANSWER biological populations of the same species become isolated from each other to an extent that prevents or interferes with genetic interchange the two main mechanisms that can cause allopatric speciation, and identify which mechanism is thought to be more common in freshwater systems - ANSWER a) dispersal i) rare for many taxa (low dispersal increases isolation) b) vicariance (barrier between two things) i) more common than dispersal as the mechanism of speciation Describe three ways that vicariance can occur in freshwater systems - ANSWER a) drainage re-arrangements b) mountain uplift c) ????? Explain why freshwater species are inherently vulnerable to extinction - ANSWER a) habitats are small and isolated b) dispersal is rare for many taxa (low dispersal increases isolation) c) extinction more likely than natural range expansion Describe a vernal pool - ANSWER a) habitat may be seasonal or temporary b) depressions w/ hard underground layer - prevent draining c) rain fills pools in winter d) water evaporates over spring e) completely dry in summer & fall explain why vernal pools are more common in Mediterranean-type climates - ANSWER -vernal pools require filling in the rainy seasons and then drying in late spring and summer which is common in mediterranean-type climates identify adaptations that animals employ in these ephemeral habitats (vernal pools) - ANSWER i) disperse to another habitat
iv) oxygen difference across thermocline not pronounced v) not a lot of sediment, mud, organic buildup b) mesotrophic = moderate productivity i) older, some sediment build-up (not just rocks) ii) medium levels of nutrients iii) some seasonal algal growth c) eutrophic = high productivity i) shallow, gentle slope ii) high levels of nutrients iii) low visibility iv) oxygen difference across thermocline pronounced
Describe the causes of eutrophication in lakes - ANSWER a) natural eutrophication i) given enough time, lakes will fill and disappear ii) result of lots of biological activity (lots of plant and algal growth) b) anthropogenic eutrophication i) human inputs of nitrogen and phosphorus ii) cultural eutrophication: we are doing something unnatural to get growth
Explain nutrient limitation and be able to interpret graphs that show nutrient limitation. - ANSWER a) liebig's law of the minimum i) primary production is limited by the nutrient (N, P, Fe, etc.) that is least available to fulfill the producers' requirements
Explain which nutrient tends to be most limiting in freshwater systems and why, and describe the Ontario lake experiments that led to this conclusion. - ANSWER -phosphorus is most limiting -why??????? -lake experiment??????
Identify different types of lotic systems - ANSWER a) streams b) rivers c) creeks d) brooks
Use stream order to classify streams - ANSWER a) 1 = smallest b) 12 = largest c) 1st - 3rd = headwater streams (80% of length of all streams on Earth) d) 7th order or larger = river
describe how physical conditions differ between low order and high order streams - ANSWER a) lower order streams i) cold (closer to source; small area) ii) fast current iii) high oxygen iv) low nutrients b) high order streams i) warmer (more space) ii) slow current iii) low oxygen iv) high nutrients (from sediments; runoff; decomposers)
Name the habitats within streams - ANSWER -inner portion of bend = depositional; -outer portion of bend = erosional -pool -run
i) terrestrial consumers eat river organisms
shredders - ANSWER a) feed on CPOM i) have powerful jaws to shred material; excrete FPOM
collector-filterers - ANSWER i) feed on FPOM and associated microorganisms ii) feed from water column
collector-gatherers - ANSWER i) feed on FPOM and associated microorganisms ii) feed on bottom
grazers - ANSWER i) feed on biofilms (FPOM) ii) feed on periphyton (mats of microbes and algae) (1) releasing organic matter in feces
CPOM - ANSWER a) coarse particulate organic matter i) from wood and leaf material
FPOM - ANSWER a) fine particulate organic matter i) from feces of herbivores (shredders) feeding on CPOM ii) from biofilms (microbial mats)
DOM - ANSWER dissolved organic matter
Identify riparian habitats and the characteristics of riparian habitats - ANSWER ???????
Describe how riparian habitats benefit streams - ANSWER ???????
Recall the types of freshwater (FW) habitats we find in SoCal - ANSWER a) vernal pools i) depression that collects water ii) keep water for amount of time and highly variable iii) shrimp lay eggs that stay dormant for a certain amount of time b) lakes i) most are manmade reservoirs c) creeks i) pretty small d) rivers i) lots of development in coastal California ii) high density of humans
Identify ways in which SoCal FW habitats are altered - ANSWER a) dams b) channelization c) introduction of nonnative species i) American bull frogs d) spread of disease and parasites
Describe the types of animals found in local FW habitats - ANSWER a) algae b) plants c) invertebrates i) highly regulated d) fishes i) highly variable e) herpetofauna i) spadefoot
vii) very productive ecosystems viii) abundance of plants and animals (lily pads, cattails, and reeds provide habitat for waterfowl and small mammals)
Prairie potholes - ANSWER -type of marsh i) depressional wetlands ii) upper Midwest iii) formerly glaciated landscape iv) fill with snowmelt and rain in spring (can stay went in summer if lots of rain) v) submerged and floating aquatic plants in middle vi) bulrushes and cattails closer to edges
vernal pools - ANSWER -type of marsh i) seasonal depressional wetlands ii) occurs in Mediterranean climate conditions of the west coast and in glaciated areas of northwest and Midwest iii) shallow water for variable periods from winter to spring iv) may be completely dry for most of the summer and fall v) hard bedrock from underneath that keeps water from going into ground vi) lots of endemic species vii) species form cysts and hang out in the dry state and come back to life when water comes back viii) threatened system with development, climate change, changes to water drainage (1) in cali 90% of vernal pools not in existence anymore
swamps - ANSWER i) wetland dominated by woody plants ii) saturated soils during growing season iii) standing water certain times of the year
iv) highly organic soils form a thick, black, nutrient-rich environment for the growth of water-tolerant trees
Bogs - ANSWER -type of peatland i) spongy peat deposits, acidic waters, thick carpet of sphagnum moss (1) sphagnum creates bogs by holding water and creating acidic conditions (slows down decomposition) ii) receive all or most of their water from precipitation (rather than from runoff, groundwater, or streams) (1) found only in areas with abundant rainfall (none in cali) iii) low in nutrients needed for plant growth iv) prevent downstream flooding by absorbing precipitation v) cranberries grow in bogs
fens - ANSWER -type of peatland i) previous to bogs ii) peat-forming wetlands that receive water and nutrients from sources other than precipitation (1) unslope sources through drainage (2) surrounding mineral soils (3) groundwater movement iii) less acidic than bogs iv) higher nutrient levels than bogs v) much more diverse plant and animal community than bogs vi) receive significant water and nutrients from a groundwater source vii) groundwater-fed fens are widespread in the California mountains in the cali mountains of the sierra, nevada, coast range, and southern cascades
Explain what happens in the process of succession from fen to bog - ANSWER a) fen is a
♣ only 0.3% is in surface water such as lakes, swamps and rivers (this makes up 0.009% of water on earth)
Explain the components of the hydrological cycle - ANSWER • water enters air o evaporation: liquid to vapor o evapo-transpiration: transpiration from plants + evaporation from soils o sublimation: ice directly to vapor
- water leaves air o precipitation: H2O condenses in air and precipitates to surface
understand how the hydrological cycle is affected by geological features, such as mountain ranges - ANSWER • as air rises over the mountain it cools, releasing its moisture as rain
**- once over the mountain, the air descends warming and taking up moisture
- atmosphere connects marine and freshwater systems
- more water evaporates off ocean than is returned as rain
- water is retained on land in ecosystems and water table
- water returned to ocean via runoff (rivers)**
Identify global and seasonal patterns of solar radiation - ANSWER • at the equator, solar energy strikes earth directly (high influx of energy per unit area) o greater solar intensity and less variable day length
- at high latitude, incoming solar energy strikes earth at an angle, resulting in lower fluxes of energy per unit area (larger area but long distance) - above sun o spring in north; fall in south - right o winter in north; summer in south o in January the southern hemisphere receives more solar energy per unit area than at
other time of the year
- bottom o fall in north; spring in south - left o summer in north; winter in south o because of earth's tilt, the northern hemisphere receives more solar energy per unit area in July than at other times of the year
How global and seasonal patterns of solar radiation affect where organisms are found - ANSWER ??????
Identify the general global patterns of precipitation and how these patterns are affected by solar radiation - ANSWER • Solar radiation drives climate
**- hottest air rises at the equator (draws up moisture)
- air cools, rains at equator
- air sinks, moves N & S, no rain at 30 N and 30 S
- rainforests and deserts -** descending air warms taking up moisture and generating arid climates at the subtropical highs
Contrast the difference between maritime and continental climates - ANSWER • water heats and cools more slowly than land
**- northern hemisphere: more land; wider range of temps
- southern hemisphere: less land; narrower range of temps**
Explain the Coriolis effect and how it affects surface currents in the ocean - ANSWER • in the northern hemisphere, the surface layer of water moves 45 degrees to the right
**- in the southern hemisphere, the surface layer of water moves 45 degrees to the left
- caused by westerlies and northeast trade winds**
Explain the relationship between water and oxygen in aquatic environments, and how abiotic factors and biological process affect oxygen concentrations - ANSWER • oxygen is low at night o respiration (no sun; take up O2; release CO2)
- oxygen is high during the day o photosynthesis (takes up CO2; release O2) - lower temp = higher O2 content o gasses can be higher in concentration in colder liquids - freshwater holds more oxygen
Explain why CO2 concentrations are greater with depth - ANSWER • less light so less photosynthesis
**- the dead species go to the bottom and get decomposed releasing CO
- there is an oxygen minimum zone** o respiration outdoes photosynthesis and the decomposition rate is high
Identify the nutrients that are most important in marine and freshwater systems and the sources of nutrients in these systems - ANSWER • C, H, O, N, P, Mg, Cu, Mn, Zn, and Mo
- sources: o terrestrial o atmospheric o recycling within system o transport from upstream in watershed o tart - marine o N is the most limiting followed by P and Fe o when you add N you get an increase in photosynthetic organisms - freshwater o P is the limiting nutrient
- Nitrogen inputs o physical advection (nitrate) from below the nutricline (brought up from deeper water) o atmospheric input of ammonia and nitrate by rain or dry deposition o N2 fixation by bacteria o Ammonium from bacterial decomposition of organic matter in sediments (get recycled when animals get decomposed) o we can now synthesize nitrogen; doubled the amount on earth (can be a problem)
List the typical salinity levels (ppt) of ocean, brackish and fresh waters - ANSWER • ocean o 96.5% pure water and 3.5% dissolved solids and gases o around 35 ppt but varies between 33 to 37 ppt
- brackish o between 0.5 and 17 ppt - freshwater o 0.5 ppt or less - Mostly sodium chloride causing the salinity followed by sulfate and magnesium
Identify the relationship between pH and CO2 - ANSWER • average pH is 8.
**- more CO2 = lower pH because more H+
- CO2 + H2O = carbonic acid = H+ + bicarbonate**
Recall how the viscosity of water compares to air and other liquids - ANSWER • viscosity is the ability to move
**- water has low viscosity for a liquid but 100 times higher than air
- water also has high surface tension**
Explain how temp and salinity affect density of water, why ice less dense than cold water, and why is this important when understanding aquatic systems in winter/arctic
Describe how heat conduction in water affects organisms and animal adaptations to deal with temps - ANSWER • poikilotherms - variable temps o ectothermic: acquire heat from environment o behavior thermoregulation o fish, inverts
- homeotherms - maintain fairly constant temp o endothermic: generates heat metabolically o mammals, birds **- higher heat conductance in water
- metabolic heat conducted away from organism -** lose metabolic heat at gills or other gas exchange site **- difficult to breathe water and be warm blooded
- heat and marine mammals** o air breathing o large size o body fat o fur o counter current heat exchange
Explain adaptations animals have to obtain oxygen while living in or near water - ANSWER • respiration is oxygen limited
**- gills have high surface area
- gills collapse or dry out in air
- aquatic acquisition of oxygen** o lungs in marine mammals o tracheal system in some aquatic insects o diffusion by very small animals o gills found in fish and other marine invertebrates (mollusks, echinoderms)
- environment can be anoxic (very low O2 concentration) o increase SA/V ♣ small size ♣ flat or elongate body o air breathing ♣ insects, snails o oxygen carrying pigments ♣ hemoglobin ♣ fish, insect larvae, worms
different ways that aquatic organisms feed - ANSWER o filter feeding ♣ internal - suck in water and filter ♣ external - nets, filters, or mucous
- can be sessile and still feed o suction feeding o deposit feeding
adaptations aquatic animals have to control buoyancy - ANSWER • adaptations for buoyancy o use materials that are less dense than water ♣ fats, oils, air, etc. o reduce heavy materials ♣ bone, shells o ex: fatty liver and cartilage
- how to maintain water column position o adjust materials
