Indicator species are organisms whose presence, absence, or abundance reflects specific environmental conditions, serving as proxies to diagnose the health of an ecosystem. Let's evaluate each statement:
Statement A: Crayfish can indicate the quality of freshwater because changes in water acidity are stressful to them.
- Correct. Crayfish are sensitive to water acidity (pH) levels. Studies have shown that species like Austropotamobius pallipes are adversely affected by low pH levels, impacting their survival and growth. This sensitivity makes them effective bioindicators of water quality in freshwater ecosystems.
Statement B: The health of corals can indicate trends such as seawater rise and sea temperature fluctuation, which in turn are signals of climate change.
- Correct. Coral health is directly influenced by sea temperature fluctuations and sea level changes. Corals experience stress and bleaching when exposed to elevated sea temperatures, and their health can reflect broader environmental changes associated with climate change.
Statement C: Peregrine falcons are an indicator of pesticides.
- Correct. Peregrine falcons have historically served as indicator species for environmental contamination by pesticides, notably organochlorines like DDT. The accumulation of such contaminants in their prey led to population declines due to eggshell thinning. Monitoring peregrine falcon populations has provided insights into the environmental presence and impact of these pesticides.
Conclusion:
All three statements accurately describe the roles of the mentioned species as indicators of specific environmental conditions.
Answer: (4) All of the above
Peregrine Falcons: Indicators of Environmental Health
