Freshwater Ecology Practice Test

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• Which is a documented example of how an invasive species can alter nutrient cycling in freshwater systems?
• What is a key limitation when interpreting satellite-derived chlorophyll-a and turbidity in freshwater ecosystems?
• What combination of actions can promote nutrient uptake by littoral macrophytes to improve water quality in eutrophic lakes?
• Which bias is commonly considered when sampling stream macroinvertebrates?
• What do trophic position and dietary niche breadth indicate in freshwater fish communities, and how can you assess these using stable isotopes?
• Which statement best describes how stratification can influence the likelihood of algal blooms?
• Explain how nutrient input reductions at the watershed scale can lead to delayed responses in lake water quality and why persistence of legacy phosphorus matters.
• Which outcome would indicate a successful biomanipulation aimed at reducing algal blooms in a eutrophic lake?
• How do low pH and aluminum toxicity affect freshwater fish, and how might climate warming interact with these stressors?
• What is the effect of autumn turnover on the vertical distribution of dissolved oxygen in a temperate lake?
• What term would describe the group of organisms that can interbreed and produce offspring?
• How might climate change influence freshwater ecosystems through temperature-oxygen interactions and potential regime shifts?
• Which term describes the broad process of stratifying a lake into distinct temperature layers?
• Deep slow-moving water with more sediment is called which feature?
• In restoration planning, what is a key goal regarding flow variability and sediment transport?
• Which feature of wetlands enhances nitrate removal at watershed scales?
• Which term refers to tiny organisms floating in the water?
• Which factor most directly reduces Secchi depth in freshwater systems?
• During the summer stratification in a temperate lake, which statement best describes the epilimnion, metalimnion, and hypolimnion and their dissolved oxygen trends?
• Which group comprises rooted plants with stems and leaves above water (for example cattails)?
• Define biomanipulation and give an example of how it might be used to restore a eutrophic lake ecosystem.
• Describe the role of rooted aquatic macrophytes in lakes and wetlands in terms of habitat provision, nutrient uptake, sediment stabilization, and wave attenuation.
• Which aspect of ecosystem functioning is more likely predicted by functional diversity than by species richness alone?
• In what ways can aquatic macrophyte community structure influence nutrient cycling and water quality in shallow lakes?
• Which term best describes all populations living in a given area?
• Which term refers to a group of organisms of the same species occupying a defined area?
• Fast-moving outer bank of a stream with high erosion is best described by which term?
• Which statement describes how primary production and secondary production are measured or estimated in freshwater systems?
• The set of all living organisms of different species in a lake constitutes which concept?
• In wetlands, connectivity enhances nutrient processing through which microbial process?
• Which season is most associated with re-oxygenation of deep water in temperate lakes due to winds and cooling?
• What term describes all living organisms in a river and the environment they inhabit?
• What are common indicators used to assess restoration success in degraded freshwater ecosystems, and what combination of metrics would signify improvement?
• Which condition strongly contributes to cyanobacterial blooms in freshwater?
• Which zone describes deep-water conditions with little light and low oxygen?
• Which term describes organisms that eat both plants and animals?
• How does connectivity contribute to ecosystem resilience?
• Denitrification in freshwater sediments primarily removes which form of nitrogen from the water column?
• Lake turnover events influence dissolved oxygen by doing what?
• If NEP is positive, what does that imply for the ecosystem's carbon?
• Describe the differences between pelagic and benthic primary production in lakes and the implications for carbon cycling and oxygen dynamics.
• How does disturbance history influence freshwater ecosystem resilience and the likelihood of regime shifts?
• Which components are essential to balance inputs and outputs in a watershed nutrient budget?
• Which group includes plants that grow entirely underwater?
• Which term denotes the middle layer where temperature drops rapidly?
• Which term describes layering of water based on temperature?
• Which term describes the cold deep layer with low oxygen?
• Vegetated land along water that stabilizes banks and filters pollutants is called which term?
• Which metric is commonly used to assess water clarity in restoration and monitoring programs?
• Which groups would you monitor to detect a trophic cascade from predator manipulation in freshwater ecosystems?
• What monitoring indicators are typically used for cyanobacterial blooms?
• How does the concept of ecosystem services apply to freshwater systems, and what metrics would you use to quantify these services for management decisions?
• What term describes the amount of plants, animals, and nutrients in water (PAN)?
• Which term best describes a temporary desert lake that forms after rainfall?
• Which design choice best supports a valid comparison of macroinvertebrate responses across streams with different restoration levels?
• Organisms attached to surfaces like rocks and logs are called
• In a basic fish bioenergetics model, how does temperature influence growth and consumption?
• Bottom-dwelling organisms living in or on sediments are called, often used to describe species that inhabit the substrate
• In streams, which habitat is characterized by fast-moving, shallow, well-oxygenated water with coarse substrates, supporting diverse, sensitive invertebrates?
• What defines a robust bioassessment index for streams, and what does a high B-IBI score indicate?
• Beyond nutrients and organisms, connectivity in freshwater networks supports which concept?
• In oxygen-based estimates of lake primary production, what does net ecosystem production (NEP) represent?
• What is the purpose of stable isotope analysis in freshwater food webs, and what inferences do δ13C and δ15N provide?
• Dissolved oxygen thresholds are commonly used to protect aquatic life. Which statement best reflects this guidance?
• Water flowing over land into streams is described by which term?
• Which predator manipulation would best test top-down control in a freshwater ecosystem?
• Describe the concept of community succession after a disturbance and the potential trajectory of recovery.
• In a lake with periodic anoxic events in the hypolimnion, what management interventions could mitigate fish kills and maintain water quality?
• Turnover affects the phytoplankton community by altering which factors?
• Which term describes flowing-water ecosystems such as rivers and streams?
• Together, the trout population and the plant population in a stream represent which concept?
• What term describes the natural aging process where lakes and ponds gradually fill with sediment and become wetlands or forests?
• Autochthonous carbon to freshwater food webs primarily comes from which source?
• Organisms that feed on detritus, such as leaf litter and decomposing material, are called
• Which zone is associated with a fast-moving outer bank and erosion?
• Which term describes standing water ecosystems such as lakes, ponds, marshes, swamps, and bogs?
• Describe the River Continuum Concept's core idea along a river's longitudinal gradient.
• Slow-moving inner bank where sediments settle is described by which zone?
• Which metric best quantifies the flood attenuation service of a freshwater system?
• How does the hyporheic zone buffer nutrient spikes during storm events in streams?
• A U-shaped lake formed when a river meander is cut off is an ____.
• Which term refers to the warm top layer with high oxygen and productivity?
• Which zone describes the shallow, near-shore area with abundant plant life and high biodiversity?
• Distinguish littoral and profundal zones in lakes and discuss how biota and processes differ.
• What role do dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) play in freshwater light regimes and microbial processes?
• Water soaking into the ground is described by which term?
• Which term describes a group of organisms that can interbreed and produce fertile offspring?
• Which combination of factors would most likely increase cyanobacterial dominance in a lake?
• Phosphorus sorption-desorption dynamics influence lake response to external phosphorus inputs. Which statement is correct?
• The effect of removing connectivity by dams or channelization is to?
• Which term describes producers that convert light energy into chemical energy?
• What factors influence the accuracy of index-based bioassessment in streams, and how can you improve reliability?
• Which term refers to flowing water ecosystems like rivers and streams?
• A man-made lake formed by damming rivers is a ____.
• Which microbes are typically involved in nitrification and denitrification in freshwater systems?
• Which statement best describes the primary control of nutrient burial and release in shallow lake sediments?
• Organisms living in or on bottom sediments are called
• Ecological signs indicate eutrophication in freshwater systems, and what management thresholds identify when degradation becomes a concern?
• A small desert depression that occasionally fills with water is a ____.
• How can stable isotope mixing models be used to quantify the proportional contributions of autochthonous and allochthonous carbon to freshwater food webs?
• Which open-water zone is described as the area where light penetrates but no rooted plants grow?
• Secchi depth is the depth at which a Secchi disk disappears from view; how does this relate to light penetration, water clarity, and phytoplankton productivity in freshwater systems?
• If GPP is 5 units and R is 0 units, what is NEP?
• A body of water where light penetrates all the way to the bottom is a ____.
• Which term describes the concept that includes both living organisms and their physical environment in a habitat?
• How do temperature and nutrient availability jointly influence cyanobacterial bloom formation in freshwater lakes?
• Describe the microbial loop and its influence on carbon and nutrient cycling in freshwater ecosystems.
• Decomposers that break down organic matter are best described as
• Which term describes a water system characterized by currents such as streams and rivers?
• Plants and algae that make their own food are called
• Which term describes all individuals of the same species living in a defined area?
• Which group includes plants with leaves floating on the surface (for example water lilies, duckweed)?
• Compare methods for estimating lake primary production: oxygen-based (DO/diurnal) versus carbon-based (14C bicarbonate uptake); which method yields gross production with lab requirements?
• Explain how algal community structure shifts with changes in nutrient ratios and light availability; what patterns indicate light limitation versus nutrient limitation?
• Which term describes organisms that eat dead organisms?
• Shallow fast-moving water with high oxygen is typical of which feature?
• Differentiate nitrification and denitrification, including redox conditions, key microbial players, and where each process typically occurs in freshwater systems.
• What is the role of the sediment-water interface in nutrient cycling in shallow lakes?
• Turnover can trigger spring phytoplankton blooms or alter what aspect of the phytoplankton community?
• Which term describes high nutrients, high productivity, green and turbid water?
• Which group includes plants growing entirely underwater (for example hydrilla, elodea)?
• Which term describes organisms that live on the water surface?
• Describe the EPT index and how macroinvertebrate communities reflect water quality; what do high versus low EPT richness indicate?
• The term used to classify inland waters that are not part of a current, flowing system is ____.
• Which statement correctly describes carbonate buffering and alkalinity in freshwater?
• Urbanization with more impervious surfaces tends to cause which hydrological change in streams?
• Which zone is characterized by deep water with little or no light and low oxygen?
• How is the Redfield ratio used to infer nutrient limitation (N vs P) in freshwater systems, and what typical thresholds indicate limitation?
• What is the ecological significance of the littoral-pelagic coupling in lakes, and how might disruption affect community structure?
• Which statement best describes the hyporheic exchange in streams?
• Which term describes free-swimming organisms such as fish?
• Which redox condition favors nitrate formation via nitrification?
• Which factors contribute to variability in trophic transfer efficiency across lakes and streams?
• Explain the concept of functional diversity and why it's important to assess beyond taxonomic diversity.
• Carnivores that eat other animals are
• In a basic fish bioenergetics model, what determines growth?
• What does flow regime mean and how do flood pulses influence ecosystem structure?
• Which term describes free-swimming organisms such as fish?
• Which nitrogen-related process is enhanced in connected wetlands?
• Turnover’s ecological role includes which of the following?
• Peatland in poorly drained areas with moss, shrubs, and evergreen trees is a ____.
• Wetland dominated by woody plants like trees is a ____.
• In connected systems, exchange increases and recolonization is possible. Which option best reflects this?
• Which term describes a body of water where light penetration varies from a few inches to many feet?
• Which term describes a single species group within an area?
• What sampling considerations are important when comparing seasonal data from different freshwater bodies to avoid biases in ecological interpretation?
• Vegetated land along water that stabilizes banks and filters pollutants is called which term?
• Organisms that eat both plants and animals are
• Which regulatory focus is commonly used to prevent the spread of zebra mussels?
• Which metric is commonly used to estimate macrophyte biomass in streams?
• Which lake zone is characterized by nearshore light penetration supporting rooted vegetation and diverse macroinvertebrates?
• Turnover-related phytoplankton responses are most evident during which times?
• How does diel vertical migration by zooplankton and fish influence vertical nutrient transport and oxygen distribution in stratified lakes?
• Which statement best describes secondary production in freshwater ecosystems?
• Which zone is the shallow shoreline area with plant growth and high biodiversity?
• Which microbial process in the hyporheic zone contributes to nitrogen removal and is an important part of nitrogen cycling?
• Which pigment is commonly used as a proxy for measuring periphyton biomass in streams?
• Bacteria and fungi that break down organic matter are categorized as
• What components should a robust bioassessment index include?
• Compared with grazing pathways, detrital pathways typically exhibit what energy transfer characteristic?
• In lake ecosystems, which zone is the open-water region where light penetrates but rooted vegetation is not present?
• Which group refers to plants rooted in the substrate with stems and leaves that rise above the water surface?
• Which pattern in a diel oxygen curve indicates a healthy, well-functioning lake compared to a stressed one?
• In a predator manipulation experiment, which outcome would support top-down control of lower trophic levels?
• How does zooplankton grazing influence phytoplankton community composition and bloom dynamics; what evidence supports top-down control?
• Which term describes the mixing of lake water layers due to temperature changes?
• Which term refers to the middle layer where temperature drops rapidly?
• Which measurements best quantify nutrient uptake by macrophytes and periphyton in field studies?
• Disruption of connectivity increases vulnerability to disturbances. Which option describes this effect?
• How do flow regime and sediment transport interact to shape river channel morphology and restoration targets?
• How does sediment grain size influence macroinvertebrate community composition in streams?
• How can drought conditions affect nutrient cycling in lakes, and what management strategy helps minimize negative impacts?
• Which internal processes are considered in watershed nutrient budgets to balance net gains or losses?
• Which term describes tiny organisms floating in the water?
• Which term best describes a wetland where woody plants predominate?
• Under stratified conditions with anoxic hypolimnion, what happens to ferric (Fe3+) and manganese oxides, and how does this affect phosphorus release?
• What are the limitations of using chlorophyll-a concentration as a sole indicator of algal bloom risk, and what complementary metrics improve assessment?
• What does hydrologic connectivity among streams, rivers, lakes, and wetlands primarily enable?
• Which indicator would most strongly signal improved habitat complexity during restoration?
• What is the typical trophic transfer efficiency in freshwater ecosystems?
• The breeding group of pink salmon in a river is an example of which concept?
• What conditions promote denitrification in wetlands, and why is this process significant at watershed scale?
• Which term describes the warm top layer with high oxygen and productivity?
• In a stream with several species of macroinvertebrates and fish, the combined biotic groups represent which term?
• A single population of bluegill sunfish in a pond would be best described as which term?
• Why are wetlands effective at nutrient retention, and which hydrological features promote this efficiency?
• Which term describes organisms that live on the water surface?
• Which term best describes a group of different species living in the same area?
• How does nutrient remineralization within sediments affect downstream productivity in lakes and reservoirs?
• Which term describes a broad ecological unit consisting of living organisms and their physical environment?
• Dead animal remains are called
• Deep slow-moving water with more sediment is called which feature?
• Bottom-dwelling organisms living in sediments are collectively called
• Which term describes lakes with moderate nutrients and productivity?
• Water flowing over land into streams is described by which term?
• Which term describes lakes or waters with low nutrients, low productivity, clear water, and little life?
• Living and nonliving components interacting in an environment are described by which term?
• Define nutrient spiraling in streams and explain the meanings of uptake length Sw and uptake rate Vf; what does a shorter Sw indicate about ecosystem demand?
• Downward movement of water through soil is described by which term?
• Which factor would most likely reduce nutrient processing in wetlands?
• What is the role of biogeochemical hotspots in freshwater ecosystems, and where might you expect to find them?
• Which term best describes all the different species present in a lake?
• Herbivores that eat producers are
• Describe ecological and regulatory implications of Zebra mussel invasion on freshwater systems.
• Wetland with soft-stem plants like cattails and grasses is a ____.
• Turnover redistributes nutrients within the water column. Which is a likely consequence?
• DIN includes nitrate, nitrite, and ammonium. Which statement best describes their influence on algal community composition?
• What combination of factors determines whether a lake's recovery after disturbance returns to pre-disturbance conditions or shifts to an alternative stable state?
• Which term describes inland waters that have little to no current and are characterized by standing water such as lakes and ponds?