Aquatic sediments – State

Aquatic sediments – State

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• Pressures
• Management response
• State
• Vulnerability

Physical-chemical state Changes to the aquatic sediment load entering a wetland can affect: water clarity light penetration thermal absorption. Turbid water decreases light availability for photosynthesis and fauna dependent on visual cues, and the water absorbs the sun’s heat more readily and may result in increased evaporation rates and stratification. Toxicants and nutrients attach to sediment particles and are readily transported. Sediment deposition can infill wetlands and/or result in altered substrate grain size (e.g. change from sand to fine mud).

Biological impact Changes to the water clarity of a wetland can result in: altered primary production a loss of sensitive species.

Sediment rich water entering a wetland may result in a loss of sensitive species and a change in primary production and community structure. A decrease in light penetration will decrease photosynthesis and cause a loss of submerged plants and/or algae. This large pool of organic matter to be decomposed can greatly reduce dissolved oxygen levels.

The effects of increased sediment loads such as smothering, clogging of gills or loss of visibility (for catching prey) can kill sensitive fauna such as fish or macroinvertebrates. Sediment loads can infill wetlands, altering the wet/dry periodicity and result in a change from more aquatic species, such as grass/sedge/herbs to more terrestrial species, such as trees.

Last updated: 22 March 2013