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.
Resource‐efficient food production practices are needed to support a sustainable food system. Aquaponics, a system where fish and produce are grown symbiotically in the same water circulating system, minimizes water usage, fertilizer input, and waste production. However, the impact of aquaponics on produce quality is underexplored. We utilize objective testing, descriptive analysis, and consumer acceptance to characterize the impact of aquaponics on tomato quality. Two tomato varieties were grown in an aquaponics system and compared with soil‐grown controls across 3 years. Safety was assessed by analyzing coliforms and confirming the absence of Escherichia coli. Weight, texture, color, moisture, titratable acidity, brix, and phenolic and antioxidant measurements were assessed. A semitrained descriptive sensory panel assessed 13 tomato attributes and acceptance was determined using untrained participants. Aquaponic tomatoes were frequently lighter and yellower in color and lower in brix. Descriptive analysis indicated significant differences in several sensory attributes, though these findings were inconsistent between years and varieties. Nutrient deficiencies may explain quality differences, as iron supplementation improved outcomes. Notably, the objective and descriptive differences minimally impacted consumer acceptance, as we found no significant differences in taste, texture, or appearance liking between production method in either variety. Despite variation in produce quality across years, aquaponics tomatoes pose minimal E. coli risk and are liked as much as soil‐grown tomatoes. These findings demonstrate that aquaponics can produce products that are as acceptable as their soil‐grown counterparts.
Practical Application
Aquaponic tomatoes are as safe as soil‐grown tomatoes. Furthermore, aquaponics tomatoes are liked as much as soil‐grown tomatoes. Careful monitoring of nutrients in an aquaponic system may optimize quality. Overall, aquaponics has a minimal impact on tomato quality and thus is a sustainable food production method that can compete with conventional products on quality.
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