Flashcards Akvatisk Biologi & Naturvård

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• Which two separate water circulation systems are within the open oceans? Surface water circulation (driven by the wind) & deep water circulation (driven by cool water sinking at high latitudes).
• Where are the two water circulation systems only connected. In regions of downwelling and upwelling.
• How is the status of salinity and proportions of dissolved constituents in the sea, in contrast to inland waters? Very constant.
• To where and often what is photosynthesis limited to? Shallow waters and nutrients.
• What is the dominant energy source of many aquatic systems? Detritus.
• Which is the optimum medium for life? Sea water
• Which is the main reason for the restricted diversity in fresh waters? Low salinity.
• Where did most higher taxa in fresh waters originally come from? Directly from the sea.
• Which taxa is a notable absence from marine environments? Insects.
• Which taxa that orginated in fresh waters does now dominate marine habitats? Teleost fishes.
• Which two ecological groups can aquatic organisms be classified into? Habitat or functional group.
• Which categories does habitat-based classifications differentiate between? Pelagic, benthic, neuston and fringing communities.
• How to functional classifications differentiate organisms? On what and how they eat.
• What are most consumers? Opportunistic.
• Which factor are dispersal mechanisms determined by? The occupied habitat.
• What way of life in one or more life cycles stages has developed in several groups of aquatic animals? Parasitism.
• What is the microbial loop important in? Transferring dissolved organic carbon (DOC) into a particulate form that is then available for large consumers.
• What is the distributuion and relative abundance of aquatic organisms largely determined by? Disturbance.
• What can disturbance at a low frequency cause? Enhanced species diversity by inducing patchiness.
• Which processes are terrestrial communities primarily determined by? Biotic processes.
• What is the fundamental determinant of aquatic community structure? Frequency and intensity of physical disturbance.
• What are some examples of mechanisms in ecological functioning that aquatic organisms are responsible for? Food supply, nutrient recycling, structural habitats and modification of physical processes.
• What is the character of a river? Undirectional flow of water.
• What determines the conditions at any one point on a river? Surrounding catchment and inputs from upstream.
• What do regularly flooded rivers have? Clearly defined floodplain.
• Through which ways do rivers interact with their catchments? Direct run-off, groundwater transfer and flooding
• Which is the primary determinant of the community structure in a river? The current.
• In which habitat do most organisms in eroding rivers live? At the bottom.
• Which factor on river beds or in lateral margins of the channel determines species diversity? Diversity of microhabitats.
• What is generally the rate of primary production in rivers? Low.
• What is the major source of energy in rivers? Detritus from catchment or from upstream.
• How can moderate disturbance enhance both the patchy nature and species diversity of river beds? By ensuring that the most competitive species do not dominate to the exclusion of all others.
• What is main definition of estuaries? Zones of transition between freshwater and marine environments.
• What are estuaries particularly charcterized by? Salinity gradients.
• What are the physiochemical conditions in an estuary mainly determined by? Relative volumes of salt and fresh water.
• Which type of sediment dominate in estuaries? Soft sediment.
• Which is the primary determinant of the distribution of organisms in an estuary? The salinity distribution.
• Which rate of salinity is too much for most fresh water organisms? An excess of 5.
• Which rate of salinity is the least that most marine species can cope with? 18 or below.
• In which salinity range are most true estuarine species common? 5-18.
• Which is the critical range in salinity that causes a break in faunal distributions? Around 7-10.
• How do planktonic species withstand the net seaward flow in estuaries? By taking advantage of differential surface and near bed flows and follow daily or seasonal cyclesof movement.
• How do estuarine species mainly adapt to sedimentation? By adopting a burrowing lifestyle.
• Estuaries are amongst the most productive habitats, yet what is much of their production based on? Detritus derived from external sources.
• What is light-limitation of primary production whitin peripheral water due to? Turbidity.
• What kind of feeders are most estuarine invertebrates? Generalist deposit feeders.
• Which types of temporary predators are members of the estuarine fauna? Wading birds at low tide and marine fish at high tide.
• What are the reasons for the low species diversity in estuaries? Combination of fluctuating salinity, lack of habitat heterogeneity(main cause) and geological transience of estuaries.
• Which the most productive region of the oceans and which has a high diversity of environments? Coastal seas.
• What is the environment in coastal regions dominated by? Tides, particulary along the shore.
• What is the ecology of intertidal areas primarily a function of? The degree of water movement and the underlying geology.'
• Which type of organisms is dominant on rocky shores? Sessile organisms.
• Which type of organisms is dominant on soft sediment shores? Mobile burrowers.
• Which type of production dominate the enery input in the water column? Phytoplankton production.
• In response to which factors do phytoplankton production generally show distinct seasonal patterns? Temperature, light, nutrient ability and grazing pressure.
• To which areas in benthic communities is primary production limited to? Shallow waters, particularly the rocky intertidal and sublitoral.
• Which is the primary energy source for most subtidal systems? Detritus.
• Which factors determine community structure in hard substratum systems? Physical disturbance and predation.
• Which factor contributes to patterns of zonation seen on rocky shores? Competition.
• Which is the primary determinant of community structure in soft sediment systems? The type of sediment.
• How is benthic community structure often explained, at least partially? By variability in recruitment (supply-side ecology).
• How is benthic community in soft sediments often explained? By individuals which have survived disturbance (relicts).
• Which kinds of control of the plankton communities in the water column, are there good evidence for? Predation and competitive control (relative importance varying seasonally).
• What does the harvesting of wild populations of marine organisms have major effects on? Target species and upon the environment in which they are caught.
• Within what places in the Earth's surface are lakes created? Depressions in the Earth's surface.
• How will an outflow river handle fluctuations in volume? It will dampen them.
• What do saline lakes generally lack, making them fluctuate widely in surface and volume? An outflow.
• What do lakes have in common with the open sea? Thermal stratification, often seasonally.
• What is the cause of oxygen depletion at depth in a lake? Lack of mixing between the surface layer (epilimnion) and deep layer (hypolimnion).
• Which is the dominant source of primary production in deep lakes? Phytoplankton.
• What factors limit the primary production in temperate zones in the winter? Temperature and light.
• What factors limit the primary production in temperate zones in the summer? Nutrient depletion and grazing.
• Which factor affects the primary production in the tropics? Seasonal variations in hydrology.
• Which is the dominant biotic interaction in lakes? Predation.
• What are the strategies developed by organisms to avoid predation in lakes? Structural defences, life-cycle strategies and avoidance behaviour.
• What is rare in general in lakes but common in ancient lakes? Endemism.
• What does the succesional process that infills a lake involve? Eutrophication.
• What do antropogenic eutrophication of and introduction of alien fish species in lakes demonstrate? That lakes act as single ecological units.
• What is the defintion of a wetlland? An area of land defined by a water table which is permanently or frequently high, ledaing to waterlogged or flooded soils.
• How are aquatic marginal wetlands created? By rivers, lakes and the sea.
• How are mires fed? By groundwater, overland run off or precipitation.
• Which type of soils is characteristic for wetlands? Anoxic soils, that often contain toxic chemicals and support bacterial activity which removes nitrates.
• Where from do aquatic marginal wetlands get their nutrient supplies replenished? From the parent water body or if seasonally dry, through decomposition.
• How is the nutrient status of permanently flooded mires? Poor.
• What adaptation in wetland plants makes a marked vertical zonation over very small elevations? Their specific tolerances to environmental conditions.
• What factor are wetland plants very sensitive to? Fluctuations in water level.
• Which types of wetlands are amongst the most productive environments on Earth? Seasonally flooded wetlands (flood wetlands) and those on the edge of open water bodies (fringe wetlands).
• Which type of wetland have very low productivity? Rain fed mires.
• What type of material can slow decomposition in waterlogged soils give rise to? Peat (partially decomposed plant remains).
• What type of food source do most invertebrates in wetlands consume? Detritus.
• What is the reason that wetlands diversity supports terrestrial and aquatic organisms at different times of the year? Diversity is enhanced by seasonal changes, like by flooding.
• How are processes like formation and development in wetlands mediated? By organisms inhabiting them
• What ability does Sphagnum moss possess that can give rise to large mires? They can control the water table to its own advantage.
• How does normally a groundwater fed mire develop? From infilling a lake or an arm of the sea.
• What types of material do wetlands absorbe? Excess nutrients and floodwater.

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