GS1 PYQ (Mains Answer Writing): Ocean Currents and Water Masses | Geography for UPSC CSE PDF Download

How ocean currents and water masses differ in their impacts on marine life and the coastal environment? Give suitable examples. (UPSC GS1 Mains)

The ocean water is dynamic. Its physical characteristics like temperature, salinity, density and the external forces like of the sun, moon and the winds influence the movement of ocean water. Ocean currents are the continuous flow of huge amount of water in a definite direction. Water moves ahead from one place to another through ocean currents.
Ocean currents has direct impact on the climate and economy of the region. Common water masses in the world ocean are: Antarctic Bottom Water (AABW), North Atlantic Deep Water (NADW), Circumpolar Deep Water (CDW), Antarctic Intermediate Water (AAIW), Subantarctic Mode Water (SAMW), Arctic Intermediate Water (AIW), North Pacific Intermediate Water (NPIW), the central waters of various oceanic basins, and various ocean surface waters.
Ocean currents and water masses differ in their impacts on marine life and the coastal environment in different ways: 

• Impact on biodiversity - The physical parameters of water masses are essential because they structure the water masses and determine the various habitats that provide the environmental conditions required for marine life. 
• These conditions influence the production and the growth of plankton and fish species. The dispersion and dwelling of larvae for many benthic and pelagic species depend on hydrographical factors. They also play an important role for the exchanges between the sea and the atmosphere and between the various layers of water. 
• While ocean currents has also direct impact on the marine biodiversity. For example mixing of ocean currents becomes a ground for fishing. best example is eastern USA coast. 
• Osmo regulation and fertility- water masses formation and location of its formation has direct bearing on the marine biodiversity as salinity and temperature of water masses changes with its location. 
• While ocean currents also changes the salinity of coastal region which changes the marine biodiversity. It has also direct bearing on temperature of region also. Best example is nor that lantic drift of Atlantic region. Due to north Atlantic drift, Murmansk port of Russian region will remain ice free Impact on corals. Formation water masses near the region of corals can destroy the coral region of world. Deep coral will be more impacted by the formation of deep ocean water masses. 
• Impact on climate of regions. Impact of ocean currents has more bearing on the climate of the region. For example north Atlantic Drift has direct bearing climate of whole Europe region. Even ocean currents has direct bearing on the whole climate of the world. For example- El-Niño while ocean water masses has less impact on the climate. However in the recent time melting of glaciers and global warming may have impact on marine life. 
• Latitude heat balance. ocean currents has key role in transferring heat from tropical regions to higher latitudes. This helps in rainfall and climate of higher latitudes. Also ocean currents brings colder water from polar regions to tropical regions. 
• While water masses also changes the salinity and temperatures of oceans. for example Antarctic Bottom Water (AABW) has direct bearing on the region. 

Conclusion 
Water masses have more bearing on the deep sea marine biodiversity as deep water masses have direct bearing on these species. While ocean currents has very less bearing on deep sea water species. Further, ocean currents and their impact has been studied in much details while the impact water masses need to be studied more elaborately. Further scientific studies must be carried out study the impact these two phenomenon’s.

Topics covered - Ocean Currents, Antarctica