This thesis demonstrates how the intermittent nature of seasonal tropical fresh waters facilitates and impedes the dispersal of fish and how the variability among residual dry season pools affects the dynamics of isolated populations. I focused on the seasonal ecology of Poecilia gillii from pools in a steep gradient, intermittent stream in Costa Rica. Water temperature and dissolved oxygen concentration were affected by season, by between-pool differences, and by the interaction between seasonal and spatial influences. Seasonal flooding resulted in a catastrophic loss of fish from most pools. Population loss was influenced by the susceptibility of the pools to flooding and population density, with mortality occurring primarily in nearby desiccating "graveyard" pools. Pools increased in population size and density over the 5-month post-flood study period, and their densities converged to their pre-flood values. Variability in the rate of increase among pools was related to water quality and population density. Striking changes in the size and abundance of males over the season suggest social influences on maturation in Poecilia gillii.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.74330 |
| Date | January 1990 |
| Creators | Chapman, Lauren J. (Lauren Jeanette) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001072590, proquestno: AAINN63659, Theses scanned by UMI/ProQuest. |
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