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Intestinal barrier function of Atlantic salmon (Salmo salar L.) post smolts is reduced by common sea cage environments and suggested as a possible physiological welfare indicator.
BMC Physiol 2010; 10:22BP

Abstract

BACKGROUND

Fish farmed under high intensity aquaculture conditions are subjected to unnatural environments that may cause stress. Therefore awareness of how to maintain good health and welfare of farmed fish is important. For Atlantic salmon held in sea cages, water flow, dissolved oxygen (DO) levels and temperature will fluctuate over time and the fish can at times be exposed to detrimentally low DO levels and high temperatures. This experimental study investigates primary and secondary stress responses of Atlantic salmon post smolts to long-term exposure to reduced and fluctuating DO levels and high water temperatures, mimicking situations in the sea cages. Plasma cortisol levels and cortisol release to the water were assessed as indicators of the primary stress response and intestinal barrier integrity and physiological functions as indicators of secondary responses to changes in environmental conditions.

RESULTS

Plasma cortisol levels were elevated in fish exposed to low (50% and 60% saturation) DO levels and low temperature (9°C), at days 9, 29 and 48. The intestinal barrier function, measured as electrical resistance (TER) and permeability of mannitol at the end of the experiment, were reduced at 50% DO, in both proximal and distal intestine. When low DO levels were combined with high temperature (16°C), plasma cortisol levels were elevated in the cyclic 1:5 h at 85%:50% DO group and fixed 50% DO group compared to the control (85% DO) group at day 10 but not at later time points. The intestinal barrier function was clearly disturbed in the 50% DO group; TER was reduced in both intestinal regions concomitant with increased paracellular permeability in the distal region.

CONCLUSIONS

This study reveals that adverse environmental conditions (low water flow, low DO levels at low and high temperature), that can occur in sea cages, elicits primary and secondary stress responses in Atlantic salmon post smolts. The intestinal barrier function was significantly affected by prolonged hypoxic stress even when no primary stress response was observed. This suggests that intestinal barrier function is a good experimental marker for evaluation of chronic stress and that it can be a valuable tool to study the impact of various husbandry conditions on health and welfare of farmed Atlantic salmon.

Authors+Show Affiliations

Department of Zoology/Zoophysiology, University of Gothenburg, Sweden. henrik.sundh@zool.gu.seNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21062437

Citation

Sundh, Henrik, et al. "Intestinal Barrier Function of Atlantic Salmon (Salmo Salar L.) Post Smolts Is Reduced By Common Sea Cage Environments and Suggested as a Possible Physiological Welfare Indicator." BMC Physiology, vol. 10, 2010, p. 22.
Sundh H, Kvamme BO, Fridell F, et al. Intestinal barrier function of Atlantic salmon (Salmo salar L.) post smolts is reduced by common sea cage environments and suggested as a possible physiological welfare indicator. BMC Physiol. 2010;10:22.
Sundh, H., Kvamme, B. O., Fridell, F., Olsen, R. E., Ellis, T., Taranger, G. L., & Sundell, K. (2010). Intestinal barrier function of Atlantic salmon (Salmo salar L.) post smolts is reduced by common sea cage environments and suggested as a possible physiological welfare indicator. BMC Physiology, 10, p. 22. doi:10.1186/1472-6793-10-22.
Sundh H, et al. Intestinal Barrier Function of Atlantic Salmon (Salmo Salar L.) Post Smolts Is Reduced By Common Sea Cage Environments and Suggested as a Possible Physiological Welfare Indicator. BMC Physiol. 2010 Nov 9;10:22. PubMed PMID: 21062437.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Intestinal barrier function of Atlantic salmon (Salmo salar L.) post smolts is reduced by common sea cage environments and suggested as a possible physiological welfare indicator. AU - Sundh,Henrik, AU - Kvamme,Bjørn Olav, AU - Fridell,Frode, AU - Olsen,Rolf Erik, AU - Ellis,Tim, AU - Taranger,Geir Lasse, AU - Sundell,Kristina, Y1 - 2010/11/09/ PY - 2009/07/22/received PY - 2010/11/09/accepted PY - 2010/11/11/entrez PY - 2010/11/11/pubmed PY - 2011/3/16/medline SP - 22 EP - 22 JF - BMC physiology JO - BMC Physiol. VL - 10 N2 - BACKGROUND: Fish farmed under high intensity aquaculture conditions are subjected to unnatural environments that may cause stress. Therefore awareness of how to maintain good health and welfare of farmed fish is important. For Atlantic salmon held in sea cages, water flow, dissolved oxygen (DO) levels and temperature will fluctuate over time and the fish can at times be exposed to detrimentally low DO levels and high temperatures. This experimental study investigates primary and secondary stress responses of Atlantic salmon post smolts to long-term exposure to reduced and fluctuating DO levels and high water temperatures, mimicking situations in the sea cages. Plasma cortisol levels and cortisol release to the water were assessed as indicators of the primary stress response and intestinal barrier integrity and physiological functions as indicators of secondary responses to changes in environmental conditions. RESULTS: Plasma cortisol levels were elevated in fish exposed to low (50% and 60% saturation) DO levels and low temperature (9°C), at days 9, 29 and 48. The intestinal barrier function, measured as electrical resistance (TER) and permeability of mannitol at the end of the experiment, were reduced at 50% DO, in both proximal and distal intestine. When low DO levels were combined with high temperature (16°C), plasma cortisol levels were elevated in the cyclic 1:5 h at 85%:50% DO group and fixed 50% DO group compared to the control (85% DO) group at day 10 but not at later time points. The intestinal barrier function was clearly disturbed in the 50% DO group; TER was reduced in both intestinal regions concomitant with increased paracellular permeability in the distal region. CONCLUSIONS: This study reveals that adverse environmental conditions (low water flow, low DO levels at low and high temperature), that can occur in sea cages, elicits primary and secondary stress responses in Atlantic salmon post smolts. The intestinal barrier function was significantly affected by prolonged hypoxic stress even when no primary stress response was observed. This suggests that intestinal barrier function is a good experimental marker for evaluation of chronic stress and that it can be a valuable tool to study the impact of various husbandry conditions on health and welfare of farmed Atlantic salmon. SN - 1472-6793 UR - https://www.unboundmedicine.com/medline/citation/21062437/Intestinal_barrier_function_of_Atlantic_salmon__Salmo_salar_L___post_smolts_is_reduced_by_common_sea_cage_environments_and_suggested_as_a_possible_physiological_welfare_indicator_ L2 - https://bmcphysiol.biomedcentral.com/articles/10.1186/1472-6793-10-22 DB - PRIME DP - Unbound Medicine ER -