A freshwater clam, Nephronaias tempisquensis, was studied in its seasonal tropical environment. This particular research was conducted because many studies of unionids from temperate waters have been conducted, but little is known of unionids from tropical waters. In mussels from temperate regions, initiation of reproductive activity, the age of sexual maturity, and seasonal activities vary among species. Nephronaias tempisquensis is an endemic clam of the tropical Tempisque River drainage basin. Its reproductive activities, population fluctuations and some of the possible environmental factors affecting its distribution are analyzed Sample collection was conducted over a period of 26 months, in three phases. The first phase of the study was begun in 1976 with monthly collections of mussels in different parts of the Rio Tempisque; individual size and distribution of the population were studied The second phase of the sampling was conducted during a period of 18 months (1979-1981); clams were collected at random from Rio Tempisque, Rio Canas, and occasionally from Rio Tempisquito and Rio Salto. Analysis in vivo of the clams and host-glochidia relationships were recorded The third phase of the study was conducted in the hope of finding the clams' natural feeding habits. Clams from Rio Tempisque, Rio Tempisquito and Rio Canas were collected and examined In all phases, external factors that probably strongly influenced the clams under study were also considered: pH, nature of the substratum, water and air temperatures, light periods and predators Among the environmental parameters that were considered for this study, rainfall is the most important factor that affects the populations of Nephronaias tempisquensis Reproductive activity is related to the most favorable environmental conditions, the beginning of the summer, and during the 'little summer'. However, reproductive activity in Nephronaias tempisquensis is continuous, but increases twice a year; from November through December and January, and from June through August Sexual dimorphism of the shells of N. tempisquensis is present, though very difficult to determine without histological studies. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_27365 |
| Date | January 1983 |
| Contributors | Amador-Berrocal, Maria-Elena (Author) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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