Aquatic Bio Exam 1

Definitions

• Thalweg: The deepest, fastest flow path in a river or stream, following the lowest elevation of the channel.
• Point Bar: Depositional area on the inner bend of a meander where water velocity decreases, leading to sediment accumulation.
• Meso Habitat: Features such as pools, riffles, and banks that create habitat diversity in streams, essential for ecosystem structure and function.
• Dissolved Load: Sediment transported in solution, consisting of ions and dissolved substances from rocks and soils.
• Critical Shear Stress: Minimum stress needed to initiate particle movement on a riverbed, representing the threshold for sediment transport.
• Laminar Flow: Smooth fluid movement with minimal mixing, characterized by parallel layers of fluid.
• Turbulent Flow: Chaotic and irregular fluid movement with swirling patterns, affecting sediment transport and habitat.
• Slope: Influences the shape, depth, and width of rivers, affecting flow characteristics like sinuosity.
• Junk: Non-target species caught while fishing for commercially valuable species.

Short Answer

• Bankfull: The water level at which a river reaches the top of its banks. Flooding occurs above this level, indicating effective discharge and the area where the channel's shape is influenced. Indicators include soil changes, vegetation destruction, and root exposure. Commonly occurs every 1-2 years.
• Lake Stratification/Turnover: Temperature changes create distinct layers in lakes, including the warm upper (epilimnion), transitional (metalimnion), and cold bottom layer (hypolimnion). Turnover, occurring in spring and fall, mixes water layers, while stratification occurs in summer, crucial for aquatic organisms as it maintains oxygen levels and nutrient distribution.
• Mesohabitats: Distinct areas within streams that enhance biodiversity and influence water quality through erosion and deposition interactions. Examples include pools, riffles, and runs.
• Flood Pulse Concept: Periodic flooding connects rivers and floodplains, enriching nutrients and providing breeding habitats, while enhancing ecological productivity. Low-order streams have unpredictable pulses, affecting species adaptations and nutrient cycling.
• Four Dimensions of Lotic Ecosystems: Comprises longitudinal (upstream-downstream), transverse (river-groundwater), vertical (water column interactions), and temporal dimensions (timing of ecological events), affecting matter and energy exchanges in aquatic ecosystems.

Essay: Flow Regime

• Components: Includes timing, duration, magnitude, frequency, and rate of change, essential for ecological integrity.
• Temporal Dimension: Determines predictability and frequency of ecological events.
• Impact on Ecological Integrity: Flow regimes influence water quality and habitat sustainability in aquatic ecosystems.
• Human Impacts: Alterations to flow regimes due to human activities can significantly affect ecological health.
• Hydrograph: A graphical representation of river flow over time can illustrate changes before and after human impacts or natural events.

Test your knowledge with this Aquatic Biology Exam 1 quiz. It covers key definitions such as 'thalweg' and 'point bar', which are essential for understanding river dynamics and sedimentation processes. Challenge your understanding of aquatic ecosystems and river morphology.