Grantee Research Project Results
The Impact of Ultraviolet Radiation on Estuarine Crab Larvae
EPA Grant Number: U914965Title: The Impact of Ultraviolet Radiation on Estuarine Crab Larvae
Investigators: Anastasia, Jean R.
Institution: The State University of New York at Stony Brook
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Marine Biology , Academic Fellowships , Biology/Life Sciences
Objective:
The objective of this research is to answer the following questions:
1. Are estuarine crab larvae that remain in near-surface waters affected by ultraviolet radiation (UV)?
2. Do these larvae suffer increased mortality because of photodamage, or do they have adaptations, such as pigmentation, to counter their increased exposure to UV?
Approach:
Larvae were placed in trays that were either covered with plexiglass to block UV or open to full sunlight. These trays were floated in the field, and larval survival was monitored daily. Light intensity also was measured daily with a LiCor meter. If chromatophores can protect larvae from UV, then larvae may expand their chromatophores in direct response to UV. The dispersion index of a chromatophore was scored on each larva. Larvae were placed in small culture dishes either exposed to full sunlight or covered with plexiglass to block UV. After 1, 5, or 10 minutes of exposure, larval chromatophore dispersion indices were again scored. The degree of dispersion was quantified using a five-point scale. If UV is an important factor and chromatophores protect larvae from UV, larvae are expected to expand their chromotaphores as they near the surface, and condense their chromatophores as they move lower in the water column. The results of this experiment were correlated with larval vertical migration patterns to see if this hypothesis is supported. Larvae were kept in small culture dishes in complete darkness in the laboratory. Every 2 hours, the dispersion indices of three larval chromatophores were scored on each of 10 larvae. Endogenous vertical migrations of larvae were documented by placing larvae in 180-cm long tubes in the laboratory in darkness and counting the number of larvae in each 10-cm section of the tube every 2 hours with the aid of dim red light. These data were correlated with rhythms of chromatophore dispersion, and will be correlated with vertical migrations in the field with and without UV.