Ship pollution Marine pollution

a cargo ship pumps ballast water on side.

ships can pollute waterways , oceans in many ways. oil spills can have devastating effects. while being toxic marine life, polycyclic aromatic hydrocarbons (pahs), found in crude oil, difficult clean up, , last years in sediment , marine environment.

oil spills emotive of marine pollution events. however, while tanker wreck may result in extensive newspaper headlines, of oil in world s seas comes other smaller sources, such tankers discharging ballast water oil tanks used on return ships, leaking pipelines or engine oil disposed of down sewers.

discharge of cargo residues bulk carriers can pollute ports, waterways, , oceans. in many instances vessels intentionally discharge illegal wastes despite foreign , domestic regulation prohibiting such actions. absence of national standards provides incentive cruise liners dump waste in places penalties inadequate. has been estimated container ships lose on 10,000 containers @ sea each year (usually during storms). ships create noise pollution disturbs natural wildlife, , water ballast tanks can spread harmful algae , other invasive species.

ballast water taken @ sea , released in port major source of unwanted exotic marine life. invasive freshwater zebra mussels, native black, caspian, , azov seas, transported great lakes via ballast water transoceanic vessel. meinesz believes 1 of worst cases of single invasive species causing harm ecosystem can attributed seemingly harmless jellyfish. mnemiopsis leidyi, species of comb jellyfish spread inhabits estuaries in many parts of world. first introduced in 1982, , thought have been transported black sea in ship s ballast water. population of jellyfish grew exponentially and, 1988, wreaking havoc upon local fishing industry. anchovy catch fell 204,000 tons in 1984 200 tons in 1993; sprat 24,600 tons in 1984 12,000 tons in 1993; horse mackerel 4,000 tons in 1984 0 in 1993. jellyfish have exhausted zooplankton, including fish larvae, numbers have fallen dramatically, yet continue maintain stranglehold on ecosystem.

invasive species can take on once occupied areas, facilitate spread of new diseases, introduce new genetic material, alter underwater seascapes, , jeopardize ability of native species obtain food. invasive species responsible $138 billion annually in lost revenue , management costs in alone.