Water Quality & Management Flashcards

Which parameter best quantifies the capacity of water to resist acidification from acid rain or acid mine drainage?

Answer: Acid neutralizing capacity (ANC) / alkalinity

Acid neutralizing capacity (ANC), measured as alkalinity in meq/L or mg/L CaCO3, represents the buffering reserve that neutralizes inputs of strong acids.

In a fish production pond, supersaturation of dissolved gases (particularly nitrogen) can cause which condition in fish?

Answer: Gas bubble trauma (gas bubble disease)

When dissolved gas pressure exceeds atmospheric pressure by roughly 110%, gas bubbles form in fish tissues and blood, causing emboli, exophthalmia, and mortality (gas bubble disease).

Which management action is most effective at reducing total phosphorus concentrations in an agriculturally impacted lake over the long term?

Answer: Watershed-level best management practices (BMPs) to reduce nonpoint source phosphorus inputs

Reducing phosphorus loading at its source through watershed BMPs (buffer strips, cover crops, reduced fertilizer applications) is the only sustainable long-term solution to lake eutrophication.

The relationship between water hardness and ammonia toxicity to fish indicates that:

Answer: Hard water reduces ammonia toxicity because calcium competes with ammonia at gill ion-transport sites

Calcium ions in hard water compete with ammonia at gill transport sites, reducing uptake and conferring some protective effect against ammonia toxicity.

A recirculating aquaculture system (RAS) manager notices nitrate accumulating above 200 mg/L. The most appropriate long-term management strategy is:

Answer: Implement denitrification via anoxic biofilter or increase water exchange rate

Denitrification by heterotrophic bacteria under anoxic conditions converts nitrate to nitrogen gas, providing the only biological route for nitrate removal in RAS.

What is the primary advantage of measuring chlorophyll-a concentration over visual observation of water color for assessing algal biomass?

Answer: Chlorophyll-a provides a quantitative, species-independent measure of phytoplankton biomass

Chlorophyll-a is a quantitative pigment common to all phytoplankton that provides an objective, measurable proxy for algal biomass regardless of community composition.

Under the Clean Water Act, states must designate beneficial uses for water bodies and set water quality standards accordingly. For a stream designated as 'cold-water fishery,' which criterion is most critical to protect?

Answer: Maximum water temperature limits protective of salmonid spawning and rearing

Cold-water fishery designations trigger specific temperature standards (e.g., 13-18°C maximums) because salmonids and other cold-water species have narrow thermal tolerances critical to survival and reproduction.