How would different types of ocean pollution would affect crabs?

Answer 1

Chesapeake Bay-nutrient pollution:
Like other aquatic animals in Chesapeake Bay, blue crabs are vulnerable to summer's low oxygen conditions. ...nutrient pollution from farms, sewage treatment plants, homes and the exhaust from cars fuels algal blooms that remove oxygen from the water. When they are trapped in crab pots, crabs often die from low oxygen levels. Also, pollution has reduced seagrass, which is crab habitat.
http://www.chesapeakebay.net/info/blue_crab.cfm
ww.nationalgeographic.com/xpeditions/ lessons/14/g68/chesapeakescienceteacher68.pdf

Oil spill: non-point oil pollution can get into coastal waters and kill crabs.
http://www.oceanservice.noaa.gov/education/kits/pollution/media/supp_pol012b.html

Fiddler crabs in marshes:
Heavy metals such as mercury, copper, and zinc are toxic to fiddler-crabs. So are pesticides.
http://www.amnh.org/nationalcenter/youngnaturalistawards/2000/gaurav.html