Open AccessEffects of Dissolved Carbon Dioxide on Cataract Formation and Progression in Juvenile Atlantic Cod, Gadus morhua L.
Author(s) -
Neves Kevin J.,
Brown Nick P.
Publication year - 2015
Publication title -
journal of the world aquaculture society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 60
eISSN - 1749-7345
pISSN - 0893-8849
DOI - 10.1111/jwas.12166
Subject(s) - gadus , biology , atlantic cod , juvenile , zoology , fish <actinopterygii> , gadidae , carbon dioxide , fishery , ecology
In this study, the effects of elevated levels of dissolved carbon dioxide were investigated in a marine recirculation system on the development of cataracts in juvenile Atlantic cod, Gadus morhua . Replicate groups ( n = 9), at an initial average weight of 23.5 ± 0.8 g, were exposed to one of the three levels of dissolved CO 2 : low (6.99 ± 0.021 mg/L), mid (12.23 ± 0.013 mg/L), or high (19.77 ± 0.029 mg/L) for 5 mo. Fish were sampled every 30 d to measure growth and assess cataract status. Fish in all CO 2 treatments developed cataracts, but cataract prevalence (%) was significantly higher after 5 mo in fish from the high CO 2 (97.8 ± 2.4%) than mid (60.7 ± 9.1%) or low CO 2 (29.6 ± 8.1%) treatments. Cataract severity, graded on a scale of 0–8, showed a similar pattern with average cataract scores of 6.0 ± 0.3, 3.0 ± 0.5, and 1.2 ± 0.3 for fish in high, mid, and low CO 2 treatments, respectively. Survival was reduced in the high CO 2 treatments (94.5%) compared to the low CO 2 treatments (97.6%). Lengths were significantly smaller in the high CO 2 treatment fish after 5 mo (217.9 ± 5.2 mm) than either mid (231.1 ± 3.1 mm) or low CO 2 (236.0 ± 4.5 mm) treatments. Weights of the fish followed a similar pattern with the fish in the high CO 2 treatments weighing significantly less after 5 mo (91.6 ± 7.8 g) than fish in the low CO 2 treatment (126.7 ± 8.8 g). Condition factor, specific growth rate, and feed conversion ratio were also negatively affected by increasing levels of CO 2 but by the end of the trial, these values were comparable to those of the low and mid CO 2 treatments. These results demonstrate that elevated levels of dissolved CO 2 significantly affect the performance of Atlantic cod in a production setting and leads to the development of cataracts. Although the physiological mechanism of CO 2 ‐induced cataract formation remains unknown, the results from this study suggest that levels of dissolved CO 2 must be given more attention in order to avoid potentially negative consequences on the growth, eye health, and survival of juvenile Atlantic cod.