International Journal of Marine Science, 2016, Vol.6, No.9, 1-20
2
considered in those type of test. Hence a paradigm shift is occurring, the significance of ecology in toxicology is
increasing and the integrated word is known as ecotoxicology (Chapman, 1995; Baird
et al
., 1996). Ecotoxicology
understands the types of effects caused by chemicals, the biochemical and physiological processes responsible for
those effects, the relative sensitivities of different types of organisms to chemical exposures, and the relative
toxicities and fate of different chemicals and chemical classes in the environment (Chapman, 2002). Highly
persistent pollutants released into the terrestrial or aquatic environment finally reach the marine ecosystem, where
it can undergo transformation, transport and accumulation.
The chemical and physical properties especially the persistence in the environment is the major controlling factor
for the transport of pollutants in the marine environment (Walker and Livingstone). Generally pollutants that
readily shift their distribution between gas and condensed phase in response to temperature variations can travel
long distance when compared with the involatile and water soluble contaminants. In the marine environment,
circulations can take the pollutants from one region to other ones. The pollutants associated with particulate matter
due to physical mixing can be vertically transported and settles at ocean sediments (Gioia
et al
., 2011). A part of
the organic matter pools like phytoplankton, which accumulated the pollutants, especially the hydrophobic ones,
can also settles to the deep ocean and carries organic matter-bound pollutants (Dachs
et al
., 2002). The pollutants
can chemically or biologically transform and bioaccumulate or biomagnify based on their bioavailability and
lipophilic character. Some of the solid pollutants, e.g. plastics, can aggregate into big size particles. Ocean
currents corrals trillions of decomposing plastic items and other trash into gigantic, swirling garbage patches. One
such massive patch was discovered in North Pacific, known as the Great Pacific Garbage Patch (Kaiser, 2010).
The schematic representation of general fate of toxic pollutants in marine ecosystem is shown in the Figure 1.
Figure 1 The general fate of pollutants in the marine environment
3 Pollutants and Their Toxic Impact on Marine Ecosystem
3.1 Heavy metals
The role of heavy metals in polluting the marine environment has gained a great deal of consideration these days.
They accumulate in marine organisms and sediments and finally reach the humans through food chain. The major
