Question

2. Shrimp fishing off the coast of Georgia was closed in 200 l , due to a drastic reduction in the shrimp population. Harvest of blue crab plummeted in 2002 and 2003 following 5 years of drought ln 2008 and 2009, however, rainfall amounts reached near normal and the shrimp population returned to pre-drought numbers. Blue crab harvest has more than doubled compared with 2002 totals. Rainfall amounts in upland regions of the state have a significant effect on the salinity of coastal estuaries, regions where open ocean and fresh water from underground aquifers and rivers mix. These estuaries are the "nurseries" for many marine animals. Speculate about possible causes for the decline of shrimp in 200 l and blue crab in 2002 and 2003, and the recovery of these species in 2009.

Answer 1

Possible causes for the decline of shirmp in 2001 and blue crab in 2002 and 2003 and recovery in 2009 because:-

• There exists a negative correlation between shrimp population and temperature. and positive correlation between shrimp and rainfall.
• Reduction in freshwater flow caused decreased dissolved oxygen caused decreased population of these species.
• By the arrival of rainfall fresh water flow increased with increasing dissolved oxygen  leading to increased population.
• harmful algal blooms also adversely affected their number.
• Change in temperature also caused disrupted migration thus directly affecting their reproductive cycle.  
• Warm water favoured algal blooms and some and growth of some flora like mangroove trees. some of these produces toxins .
• It also deteriorates water quality thus directly affecting shirmp and blue crab number.
• High temperature variability created stress.
• It also affected moulting in crabs.