Fish Habitat & Ecosystem Health Flashcards

Which index is calculated from Rapid Bioassessment Protocol data to assess the biological condition of a stream relative to minimally disturbed reference sites?

Answer: Index of Biotic Integrity (IBI)

The Index of Biotic Integrity compares observed fish community metrics to reference condition benchmarks to score the biological health of a stream.

A fisheries biologist observes that a stream's embeddedness rating is 75%. This indicates that:

Answer: 75% of gravel and cobble substrate is surrounded and covered by fine sediment

Embeddedness measures the degree to which larger substrate particles are surrounded by fine sediment; high embeddedness reduces interstitial spaces critical for spawning and macroinvertebrates.

Which chemical species of nitrogen is considered most acutely toxic to freshwater fish at elevated concentrations?

Answer: Nitrite (NO2-)

Nitrite (NO2-) is acutely toxic to fish because it competes with oxygen for binding to hemoglobin, causing methemoglobinemia (brown blood disease).

In the context of stream temperature management, which riparian vegetation strategy has the greatest short-term cooling effect on small to medium streams?

Answer: Establishing tall native shrubs and trees that provide overhead shading

Overhead shading from tall riparian trees and shrubs directly reduces solar radiation reaching the water surface, providing the most immediate stream temperature reduction.

The concept of 'environmental flows' (e-flows) in river management addresses which fundamental ecosystem need?

Answer: Defining the quantity, timing, and quality of flow needed to sustain freshwater ecosystems

Environmental flows define the flow regime—including magnitude, timing, frequency, duration, and rate of change—necessary to sustain riverine ecosystem structure and function.

Which habitat assessment component evaluates the sinuosity, gradient, and channel cross-section characteristics of a stream reach?

Answer: Channel morphology assessment

Channel morphology assessment evaluates physical parameters including sinuosity, gradient, width-to-depth ratio, and cross-section profile to characterize stream form and function.

Non-native common carp (Cyprinus carpio) degrade fish habitat primarily through which mechanism?

Answer: Uprooting aquatic vegetation and resuspending sediments, causing turbidity increases

Common carp destabilize aquatic ecosystems by rooting through sediments and uprooting macrophytes, dramatically increasing turbidity and reducing water clarity and vegetation cover.