Mr. Colvin described the major findings of a 4-year research program into the die-off of lobsters in Long Island Sound that began in the late 1990’s.  This past October, a symposium for the lobster industry and general public was held at Stony Brook University where researchers involved in this program gave presentations on their studies.  These studies included exposing lobsters to different kinds of stresses, both environmental and pathogens.  Fundamentally, the researchers came to a common conclusion on the underlying feature that fueled the die-off, which began in 1998 or 1999.   They felt it was due to exceptionally high water temperatures that prevailed for a long period of time in the bottom waters of the Long Island Sound, where the lobsters are found.  The lobster is a cold-water organism and the lobsters in the Sound experienced substantial temperature stress during this period.  This stress combined with a variety of other environmental stresses in the Sound, many of which have been in place in that environment for a long period of time.  These secondary sources of stress included hypoxia (low dissolved oxygen), a very dense population of lobsters that occurred in the Sound at that time, and hypoxia-related conditions such as releases of toxic ammonia sulfides from the reduced sediment from the hypoxic areas.  This combination of a pervasive temperature stress exacerbated by these secondary stressors resulted in population of lobsters in the Sound, especially the western Sound, that was severely stressed.  In one experiment conducted at the National Marine Fisheries Service laboratory in Milford, Connecticut, lobsters exposed just to this set of stressors (a combination of temperature, ammonia sulfides, etc) died, without any additional stressors that the lobsters in the Sound were exposed to.

In 1999, many of the lobsters examined were infected with an amoebic parasite that was the immediate cause of their death.  The current hypothesis was that the lobsters’ stressed condition made it impossible for their immune systems to suppress the infection.

Mr. Colvin noted that the potential role of pesticides in the lobster die-off continues to be a topic of discussion and much was learned about how pesticides affect lobster during the course of this research program.  Scientists were able to establish levels of acute toxicity and sub-lethal effects levels for many of the pesticides in use around the margins of the Sound.  Researchers from Stony Brook University developed new methods for measuring extremely low concentrations of pesticides.  Now that it is possible to measure pesticide levels when they are in the range of toxicity, scientists and resource managers can better gauge the effect levels of pesticides, something very worthwhile that has come out of the program.

Antoinette Clemetson of the New York Sea Grant Extension Program stated that more information about the findings of the Long Island Sound Lobster Research Program is available at the New York Sea Grant web site, www.NYSeaGrant.org.  Mr. Colvin expressed DEC’s gratitude to the organizations and individuals who were responsible for putting the recent symposium together.

 

Page last modified Sunday, January 9, 2005 by George E. Carroll