The Impact of Environmental Factors on the Physiology of the Atlantic surfclam, Spisula solidissima

Abstract

The Atlantic surfclam supports a multi-million dollar fishery in New York. Between 2002 and 2008, surfclam abundance in New York State waters along the south shore of Long Island has decreased by 63% in biomass and 75% in the total number of clams. Population age structure has drastically shifted since 2002 indicating the lack of recruitment. Only 3% of the population was made up of clams that were 6 years old and younger in 2006, compared to 21% in 2002. In 2008, 15% of the population was composed of clams less than 6 years in age. It is hypothesized that increased temperatures in recent years has caused stress in these animals, negatively impacting their physiology leading to a reduction in population size.Studies were conducted on surfclam energy balance, scope for growth and immune function to investigate the impact of temperature on the physiology of these animals. Results suggest energy reserves are used differently during warm and cooler years, which may impact survival and reproductive success. Further studies on scope for growth indicate an increased metabolic demand at 23øC compared to 19øC. Results also demonstrated a reduction in filtration rate at 23øC compared to 19øC which could cause an energetic imbalance during the critical period following spawning. Furthermore, short term energy usage was greater at 23øC, and data from immune defense studies imply surfclams are immuno-compromised at this temperature. These results strongly suggest that stressful summer temperatures negatively influence surfclam physiology.