Aquatic Bio Exam 1.docx

**[Aquatic Bio Exam 1]** **Definitions:** **Thalweg**- Describes the line or path of the deepest and most actively flowing part of a river or stream channel. Follows the channel's lowest elevation where the fastest and most concentrated flow occurs. **Point bar**- area on the inside of a meander,...

**[Aquatic Bio Exam 1]** **Definitions:** **Thalweg**- Describes the line or path of the deepest and most actively flowing part of a river or stream channel. Follows the channel's lowest elevation where the fastest and most concentrated flow occurs. **Point bar**- area on the inside of a meander, water slows down, deposition happens where sand, silt, and gravel fall out Sedimentary feature found in meandering river channels that forms on the inside bend of a river where the flow velocity is lower compared to the outer bend **Meso habitat**- ripple run pool, different types of habitat in a stream with different structures. Provides a habitat and has a range of characteristics that differ from nearby areas. Includes features such as pools, riffles, banks, reefs, etc. Important for ecosystem structure and function, habitat heterogeneity, stream health, and habitat suitability modeling. **Dissolved load**- The portion of a river or stream's total sediment load is carried in a solution rather than as suspended or bedload particles. Consists of ions and dissolved substances that have been chemically dissolved from rocks, soils, and other materials **Critical shear stress**- moment of incipient motion, stress high enough to move the particle Minimum amount of shear stress required to initiate the movement of particles on a bed or surface. Represents the threshold beyond which the forces exerted by a fluid flow are sufficient to overcome the forces holding the particles in place causing them to start moving **Laminar flow**- smooth, particles glide Fluid flow characterized by smooth, orderly, and parallel layers of fluid moving with minimal mixing between them. Fluid particles move in straight lines or smooth curves, and the flow is stable and predictable. **Turbulent flow**- eddies and swirls Fluid flow characterized by chaotic, irregular, and unpredictable movement of fluid. Involves complex and swirling patterns **Slope**- what is it and why is it important. Determines what a river looks like, how deep and wide it is, different variables, sinuosity **Junk**- Species caught while fishing for more valuable species **Give examples of each** **Short Answer:** **[What is bankfull]- most frequent flood, effective discharge, highest recurrence interval that happens every 1-2 yrs, how to find in a river** - Bankfull refers to the water level in which a river, stream, or lake reaches the top of its banks. When water levels rise above bankfull, water flows into the floodplain. Important because it shows the level at which the channel begins to form and shape itself. It's the flow that moves the most sediment over time, which helps shape and maintain the channel. Indicators of bankfull include changes in soil, destruction of vegetation, litter and debris, break in the slope of the stream bank, root hair exposure, and shelving. It has the highest recurrence interval, happening every 1-2 yrs. It's the most frequent area for floods to occur. It has effective discharge, transporting the largest percentage of sediment over a long period of time. [Lake stratification/turnover]- what causes turnover? Temperature changes causes the water density to change which mixed lake in spring and fall, during summer gets nice stratification with a metalimnion that is cold, oxygen is by thermocline, fish like to stay here - Processes that occur in lakes that affect the water's temperature, density, and mixing. Stratification occurs when a lake's water separates into distinct layers based on temperature. The layers are epilimnion (the warm upper layer), metalimnion (transition zone between epilimnion and hypolimnion), and hypolimnion (cold bottom layer). Turnover occurs when the lake's water mixes, causing water from the bottom to rise to the top and vice versa. Happens when water temperature equalizes and the layers break down. Stratification occurs during the summer in lakes deeper than 20 feet, turnover happens in fall and spring. It is caused by the upper layer of the lake getting warmer due to exposure to the sun and atmosphere. In winter, ice forms on top of the lake which prevents mixing. Stratification is important for aquatic organisms and the ecosystem. Fish like to stay in these areas. Lake turnover replenishes oxygen levels in the deepest parts of the lake and distributes nutrients throughout the lake. [Mesohabitats]- how organisms live in them and different responses of different organisms, ripple run pool, different types of habitats in a stream with different structures - Visually distinct areas within a stream that provides habitat, heterogeneity, and increases invertebrate diversity. Formed by interactions between erosion and deposition. They influence water quality which affects tolerance and trophic components of fish. It's an important spatial scale that affects structure and function of a stream's ecosystem. Examples of mesohabitats are pools, riffles, and runs. Has a range of characteristics that differ from nearby areas. [Flood pulse concept]- brings nutrients and food back into the water. Why they're important further down river systems, tend to provide habitat for species to breed, brings nutrients into the water (Found in the papers) -Explains how the periodic flooding and drying of a river controls the exchange of water, nutrients, and organisms between the river and its floodplain. Key factor in productivity and existence of the biota in river-floodplain systems. Low-order streams and heavily modified systems with leveed and drained floodplains tend to have short, unpredictable pulses. Nutrient status of a floodplain is dependent on the nutrient status of the river, due to the input of nutrients and sediment from the flood pulse. Since low order stream pulses are brief and unpredictable, organisms have limited adaptations for directly utilizing the aquatic/terrestrial zone. Moving littoral prevents prolonged stagnation and allows for rapid recycling of organic matter and nutrients which results in high productivity. Fish yields and production are strongly related to the extent of accessible flood plain, whereas the main river is used as a migration route by most fish. Flooding period typically serves as the primary breeding season for numerous fish species. [Four dimensions ] - Refers to the four dimensions of lotic ecosystems. The four dimensions are longitudinal, transverse, vertical, and temporal. Longitudinal is upstream-downstream interactions. Lateral dimension is interactions between the channel and groundwater, and temporal dimension is temporal scale. Exchanges of matter and energy between the channel and riparian floodplain system occur along the lateral dimension. - Good examples of each one **Essay:** [Flow regime]: 5 parts: Timing, duration, magnitude, frequency, rate of change Temporal dimension- how often things happen, are they predictable How it effects ecological integrity Water quality Human impacts Hydrograph- can draw one showing before and after Flow regime is important in sustaining the ecological integrity of flowing water ecosystems. It consists of five components: magnitude, frequency, duration, timing, and rate of change. These influence integrity both directly and indirectly through their effects on other primary regulators of integrity. They show regional patterns that are influenced by climate, geology, topography, and vegetation. Timing determines when certain flows or levels occur. Magnitude determines how much flow or what level. Rate of change determines how fast flows or levels change from one condition to another. Frequency shows how often certain flows or levels last. Duration determines how long certain flows and levels last. The flow regime can determine water quality, energy sources, physical habitat, and biotic interactions that all tie into ecological integrity. Hydrographs are typically used to show the expression of discharge. The curve on the graph varies based on "flashiness" or "sluggishness" of a stream that is often based on land used modifications. Disturbances can alter flow duration. Flood controls decrease flow duration while urbanization increases it. [Water quality: ] Buffer system & nutrient cycling - Soils - Precipitation - Calcium - Vegetation - Nitrogen - Loops, short vs long - Human impact