Fish Habitat & Ecosystem Health Flashcards

Which federal statute provides the primary legal foundation for protecting wetland habitats through the 404 permit program?

Answer: Clean Water Act Section 404

Clean Water Act Section 404 requires permits from the U.S. Army Corps of Engineers for discharging dredged or fill material into waters of the United States, including wetlands.

A stream reach where the channel is deeply incised below its historic floodplain and cannot access lateral floodplain areas during typical flood events is described as:

Answer: Entrenched

Entrenched streams are vertically incised into their valley floor and lack connectivity to their floodplain, reducing aquatic habitat diversity and increasing flood peak discharge.

Which measurement approach is used to estimate the amount of gravel spawning habitat available to salmon in a stream reach?

Answer: Measurement of suitable spawning patch area combined with gravel quality assessments

Spawning habitat availability is estimated by mapping and measuring the area of substrate patches with suitable grain size, embeddedness, and hydraulic conditions for spawning.

The 'shifting mosaic' concept in river ecology describes which spatial and temporal pattern?

Answer: Dynamic rearrangement of habitat patches within a river corridor as geomorphic processes operate

The shifting mosaic concept recognizes that habitat patches within a river corridor constantly change in location and character as erosion, deposition, and disturbance reshape the channel.

Which water quality parameter is used as a surrogate for estimating the phytoplankton biomass and trophic status of lakes?

Answer: Chlorophyll-a concentration

Chlorophyll-a is a direct measure of phytoplankton pigment concentration and is widely used to assess algal biomass and classify lake trophic status from oligotrophic to hypereutrophic.

Coldwater fish species are generally most vulnerable to climate change-driven habitat loss through which primary mechanism?

Answer: Upslope or upstream contraction of thermal refugia as stream temperatures rise

As water temperatures rise with climate change, coldwater thermal refugia contract to higher elevations and headwaters, reducing the spatial extent of suitable habitat for cold-adapted species.

In a Habitat Suitability Index (HSI) model for a target fish species, a suitability index (SI) value of 0 indicates:

Answer: Conditions unsuitable for the species to survive or reproduce

In HSI models, SI values range from 0 (completely unsuitable) to 1.0 (optimal), with 0 indicating that a habitat variable is at a level that precludes species presence or reproduction.