Impoundments and habitat removal are the major cause of altered connectivity in estuaries. Impoundments can impact both lateral and longitudinal connectivity, firstly, by stopping flood water coming downstream and flooding floodplain areas, and secondly, by physically stopping fish movement up/downstream. Habitat removal can result in habitat fragmentation and form a barrier to the movement of species. Changes in the connectivity between freshwater reaches and the estuary/marine environment can have a major impact on diadromous fish life cycles.
View a conceptual model of potential causes of a change to connectivity and the condition responses observed as a result of this change.
There are a number of causes and symptoms related to this stressor. The following indicators are recommended for the stressor ‘Connectivity’:
Indicators of altered connectivity sources:
- Impoundment density
- Percentage of freshwater reaches without access to the sea due to impoundments without an effective fish ladder
Indicators of direct pressure:
- Percentage of estuarine ‘shoreline’ length modified
- Percentage of estuarine ‘background habitat’ length modified
Physical-chemical condition indicators:
Biological condition indicators:
- Abundance of diadromous species
|Possible causes||Possible symptoms|
|The actions/events/situations that might induce this stress
||The actions/events/situations that might arise from a change to the stressor:
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