Aquatic Bio Exam 1

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Questions and Answers

What is a key indicator of bankfull conditions in a river?

Destruction of vegetation (correct)

Consistent water level

Absence of sediment transport

Uniform soil composition

What phenomenon occurs during lake turnover?

Decrease in oxygen levels in the deepest parts

Formation of ice on the surface

Stable stratification of water layers

Equalization of water temperature throughout the lake (correct)

What happens during the summer in lakes that are deeper than 20 feet?

Ecosystem disruption due to mixing

Cooler bottom layer temperature

Formation of distinct temperature layers (correct)

End of aquatic life cycles

How often does bankfull condition occur?

Every 1-2 years (B) Signup and view all the answers

What causes turnover in lakes?

Changes in water density due to temperature (B) Signup and view all the answers

What are mesohabitats in streams responsible for?

Increasing invertebrate diversity (B) Signup and view all the answers

What is the purpose of sediment transport in river channels?

To shape and maintain the channel (C) Signup and view all the answers

Which is true about the epilimnion layer of a lake?

It is the warm upper layer. (C) Signup and view all the answers

What does the term 'thalweg' refer to in a river or stream?

The deepest and most actively flowing part of the channel (A) Signup and view all the answers

Which statement best describes a point bar in a river?

It forms on the inside of a meander where deposition occurs. (C) Signup and view all the answers

What is the significance of meso habitats in stream ecosystems?

They contribute to habitat diversity and stream health. (C) Signup and view all the answers

What is 'dissolved load' in the context of rivers or streams?

The ions and substances chemically dissolved in the water. (A) Signup and view all the answers

What does 'critical shear stress' indicate in a river environment?

The minimum stress to initiate particle movement. (B) Signup and view all the answers

Which characteristic distinguishes laminar flow from turbulent flow?

Laminar flow has smooth, parallel layers with minimal mixing. (A) Signup and view all the answers

How does slope impact a river's physical characteristics?

Slope influences the river's depth, width, and sinuosity. (A) Signup and view all the answers

What role do mesohabitats play in stream ecosystems?

They affect the structure and function of the ecosystem. (B) Signup and view all the answers

What does the term 'bankfull' refer to in the context of rivers?

The water level at which a river reaches the top of its banks. (A) Signup and view all the answers

Which of the following best describes the flood pulse concept?

It brings nutrients and food back into the water. (D) Signup and view all the answers

How do low-order streams typically differ from higher-order streams regarding flooding?

They experience shorter, unpredictable flooding pulses. (B) Signup and view all the answers

What are the four dimensions of lotic ecosystems?

Longitudinal, transverse, vertical, and temporal. (B) Signup and view all the answers

Which component is NOT part of the flow regime?

Species diversity (C) Signup and view all the answers

What is a critical function of the lateral dimension in lotic ecosystems?

Facilitating exchanges between channel and floodplain. (D) Signup and view all the answers

What effect does the flooding period typically have on fish species?

It serves as the primary breeding season for many fish. (B) Signup and view all the answers

How does the nutrient status of a floodplain relate to the river?

It depends on the nutrient status of the river. (A) Signup and view all the answers

Study Notes

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.

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Description

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.