Seagrasses are impacted by human disturbances such as dredging, coastal development, and boating activities including mooring, anchoring, running aground, and propeller scarring. Other
disturbances like runoff from rivers can reduce
water clarity because of increased
nutrient pollution and suspended sediments entering our estuaries. Excess nutrient loads can fuel the growth of algal blooms that block light from reaching seagrasses.
Climatic disturbances including
regional droughts,
hurricanes and sea level rise can also affect seagrasses by changing the water conditions.
Abnormally low precipitation and the timing of droughts (i.e., summer) can increase salinity and water temperatures and reduce
oxygen solubility; no
oxygenation within the sediments allows the buildup of
sulfides which is toxic to seagrasses.
Hurricanes and tropical storms increase river discharge and runoff, reducing salinities and oxygen and dumping excess nutrients in receiving water bodies.
Sea level rise threatens to outpace the shoreward expansion of seagrass while increasing light limitation on the deeper portions of existing
seagrass meadows.
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