Effect of prey concentration and light on the foraging behaviour, growth and survival of Atlantic cod larvae (Gadus morhua) under laboratory conditions
This thesis describes experiments on the responses of Atlantic larval cod to two important ecological variables, prey concentration and light in terms of behaviour, growth and survival. The first ecological variable investigated was light intensity and its effect on the foraging behaviour, growth an...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
Memorial University of Newfoundland
1999
|
| Subjects: | |
| Online Access: | https://research.library.mun.ca/9434/ https://research.library.mun.ca/9434/1/Puvanendran_Velmurugu.pdf |
| Summary: | This thesis describes experiments on the responses of Atlantic larval cod to two important ecological variables, prey concentration and light in terms of behaviour, growth and survival. The first ecological variable investigated was light intensity and its effect on the foraging behaviour, growth and survival of Atlantic cod larvae from two geographical regions in the Northwest Atlantic. Larval cod originating from different geographical locations responded differently to light intensity. Larvae originating from the Scotian Shelf (SS origin) foraged, grew and survived better in low light intensity while larvae from the Northeastern Grand Banks (NF origin) performed better in high light. This difference in response to light intensity may be explained by the different spawning seasons rather a than latitudinal difference. -- The next ecological variable investigated was prey concentration. Earlier studies on larval fish indicated that growth and survival of the larvae vary with prey concentration. However, the shortcoming of most of these studies involving cod larvae was that they were short term experiments. Thus, I investigated the ontogeny of foraging behaviour of Atlantic cod larvae exposed to different prey concentrations from hatching to metamorphosis. Larvae exposed to higher prey concentration outperformed the larvae reared in lower prey concentrations in all the foraging Modal Action Patterns (MAP's) investigated in this study. But the magnitude of the foraging MAP's increased as the larvae grew regardless of prey concentration. Results also indicated development of foraging behaviour was not affected by prey concentration. -- Next, I investigated the growth and survival of Atlantic cod larvae reared in a wide range of prey concentrations. My previous experiment showed that the highest prey concentration used (4000 prey L⁻¹) may not be the optimal prey concentration to rear the cod larvae in the laboratory. In this second experiment, prey concentrations of 8000 and 16000 prey L⁻¹ were included. Results ... |
|---|