Abiotic factors in Acidic Aquatic Environments

Question 1

What does the natural ‘pH’ of a water body depend on?

Answer 1

-Catchment geology
-Surrounding vegetation

Question 2

What water systems are naturally acidic?

Answer 2

-Small streams, lakes & pools in peatland catchments
-Lakes in hard (granite) areas adjacent to sources of acidity such as pine forests
-Geothermal springs & adjacent streams

Question 3

What aquatic systems are sensitive to acid?

Answer 3

-Hard rock areas (granite)
-At risk from additional acid generating pollutants

Question 4

How do catchments cope with acidity?

Answer 4

-Enough bicarbonate present- acid is neutralized (called buffering capacity)
-Systems with large amount of limestone (high buffering capacity/ can resist effects of acid)
-Lakes & stream tend to have a near-natural pH despite the natural acidity of rainwater (pH 7)

Question 5

What are low alkalinity waters susceptible to?

Answer 5

Natural and anthropogenic acidification
(impacts of pollution)

Question 6

What are the impacts of acidity on freshwater biota?

Answer 6

-Biochemical reactions
-Physiological/ stress responses
-Recycling of nutrients
-Mobilization of metals
-Acidification
-Clear changes in food web structure and composition

Question 7

What changes happen in food web structures in acidic conditions?

Answer 7

-At long-term pH levels of 5 most organisms die
-Overall acidic waters are less diverse

Question 8

What type of wetland vegetation dominates acidic systems?

Answer 8

-Sphagnum mosses

Question 9

What algae species can tolerant acid?

Answer 9

Desmids