- SAV can be physically damaged by boat propellers (recurrent damage and long recovery period), anchors, jet skis.
- Sediment resuspension from boat wakes in shallow waters can reduce water clarity for SAV and erode wetland shorelines.
Shell bottom, SAV
- Past occurrence of seagrass wasting disease caused extensive losses of SAV habitat.
- Increased occurrence of oyster diseases has contributed to decline of shell bottom habitat and its lack of recovery.
Water column, shell bottom, SAV, wetlands
- Introduced species can compete with natives for space, light, and nutrients, and displace natives with species of lower value to native fish utilization. For example, Eurasian watermilfoil competes with native low salinity SAV plants in some areas of the coast.
- Unintended effect of nuisance species control on nontarget species
Water column, ocean hard bottom
Storm drains, accidental and intentional littering
- Fish, reptiles, birds and mammals can become entangled in debris, leading to:
- loss of mobility
- increased mortality
- greater risk of infection
- Ingestion of debris by organisms can also have lethal or sublethal effects
Sea Level Rise
Natural event accelerated by global warming
- As sea level rises, wetlands erode and “drown”, especially along steeply sloping shorelines or where inland migration of wetlands is restricted.
- Rising sea level increases salinity upstream and alters distribution and composition of fish populations
Wetlands, water column, shell bottom
Natural events, but negative effects are worse where pollutant sources occur on adjacent lands.
- The combination of storm events and sea level rise causes erosion of wetlands at a rate of about 800 acres/yr in North Carolina.
- Non-point runoff from storms can result in excessive loading of sediment and nutrients into the water column.
- Sediment runoff can silt over oyster beds.
- High nutrient loading from storm runoff can lower oxygen levels in the water, killing oysters and benthic organisms.