Environmental Salinity and Stingray Gills: From Biochemistry to Conservation BiologyEPA Grant Number: U915419
Title: Environmental Salinity and Stingray Gills: From Biochemistry to Conservation Biology
Investigators: Piermarini, Peter M.
Institution: University of Florida
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 1998 through January 1, 2001
Project Amount: $88,185
RFA: STAR Graduate Fellowships (1998) RFA Text | Recipients Lists
Research Category: Fellowship - Zoology , Biology/Life Sciences , Academic Fellowships
The objectives of this research project are to: (1) develop a physiological index to help determine whether a given freshwater elasmobranch species is euryhaline or stenohaline without conducting long-term acclimation experiments; and (2) determine what physiological factors restrict or allow freshwater elasmobranches to inhabit environments of varying salinity.
Two freshwater elasmobranch species will be used as models for this study: (1) the euryhaline (nonrestricted) freshwater Atlantic stingray (Dasyatis sabina); and (2) the stenohaline (restricted) freshwater Amazon River stingray (Potamotrygon laticeps). Biochemical and morphological changes in the gill epithelium of teleost fishes are critical for successful adaptation to varying environmental salinities. For example, certain changes in the expression of key ion regulatory enzymes (i.e., Na, K-ATPase) and ultrastructure of ion-regulating chloride cells, are characteristic of sea water versus freshwater life. In addition, these characteristics often are dependent on the salinity tolerance of the species. Similar features can be probed for in the gills of the above study species using the techniques of Western blotting, immunocytochemistry, and electron microscopy. By comparing these parameters between the study species, it can be determined what features are characteristic of euryhaline and stenohaline freshwater species, respectively. Once the characteristics of euryhalinity versus stenohalinity are established, the threatened species can be investigated. By matching up their characteristics with the model species, a salinity tolerance could be predicted. In conjunction with other biological data, this would aid in determining which species are in a more immediate need of conservation and management plans. Another benefit, especially for threatened species, is that the techniques require relatively small amounts of tissue, which could be collected without sacrificing large numbers of animals.
Expression of Na, K-ATPase and morphological characteristics associated with the gills of the euryhaline freshwater species (D. Sabina) have been established. The next step is to describe the above characteristics in the stenohaline freshwater species (P. laticeps). Completion of this component is expected by the summer of 2000. The need for further experiments will be determined at that time.