European eel larval ontogeny and physiology Insights at morphological and molecular level
The research conducted within this PhD project contributes to filling gaps in knowledge about the enigmatic life cycle of European eel (Anguilla anguilla) by addressing biotic and abiotic factors influencing early larval stages. This involves experimental studies and utilization of state-of-the-art...
| Main Author: | |
|---|---|
| Format: | Book |
| Language: | English |
| Published: |
DTU Aqua
2018
|
| Subjects: | |
| Online Access: | https://orbit.dtu.dk/en/publications/46e925f6-63b6-4b3c-a047-77317e596d10 https://backend.orbit.dtu.dk/ws/files/157131658/Publishers_version.pdf |
| Summary: | The research conducted within this PhD project contributes to filling gaps in knowledge about the enigmatic life cycle of European eel (Anguilla anguilla) by addressing biotic and abiotic factors influencing early larval stages. This involves experimental studies and utilization of state-of-the-art molecular tools elucidating links between morphology and molecular mechanisms in the quest to identify suitable rearing and feeding conditions for larviculture. As such, this thesis comprises six studies within three main topics: i) temperature, ii) salinity and iii) nutrition, influencing larval development and survival. The first three studies address the influence of temperature on early larval ontogeny. Here, Study 1 determined the thermal tolerance limits and identified an intermediate thermal environment for future larval culture with efficient growth and low frequency of deformities associated with high expression of growth hormone (improved growth) and low expression of heat shock proteins (decreased stress). Moreover, Study 2 revealed that expression of genes encoding thyroid hormone receptors and deiodinases, associated with the mediation of thyroid hormone action, show sensitivity to temperature and are involved in and during early larval development. Additionally, Study 3 shed light on the molecular ontogeny of the larval immune system under different thermal scenarios and identified an immune-compromised phase during which mortality is high and larvae are more vulnerable to pathogen infection. This will have important implications on rearing conditions and disease prevention protocols in eel hatcheries but also improve our understanding of ocean warming impacts on fish recruitment. Thereafter, experimental work focused on the salinity tolerance of these marine larvae. Here, Study 4 clearly demonstrated that culture regimes reducing salinity towards isoosmotic conditions facilitated enhanced European eel pre-leptocephalus development and survival revealing the existence of underlying, highly sensitive and ... |
|---|