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- Control of zootechnology leads to improved Cuttlefish (Sepia officinalis, L.) reproduction performance up to pre-industrial levelsPublication . Capaz, Juan Carlos; Hernández-Brooke, Daniel; Balvet, Safia; Couto, Ana T.; Alves, Alexandra; Baptista Gonçalves, Rui; Frias, Paulo A.; Andrade, José Pedro; Sykes, AntónioCephalopods are gaining momentum as an alternate group for aquaculture species diversification, not only because they are a good food source (highly appreciated in some worldwide markets) but they also have the potential to quickly reach a market size. However, there are some bottlenecks impeding the transition of culture technology from the laboratory to industry. One is related to control over reproduction in captivity. The objective of the present experiment was to verify the effects of tanks with different bottom areas/volumes on the reproduction performance of S. officinalis breeding stocks, when sex ratios were controlled a priori; and the food cost associated with such performance when individuals are fed a natural frozen diet. One hundred and ninety two juvenile cuttlefish were used to compare three different round-shaped tanks: one type with 3000L volume and two types with 9000L volume (with differences in bottom areas and water column). Individuals had their sex and maturity stage determined to establish a sexual ratio of 2 female:1 male per tank and assure that cuttlefish were still immature. Biological data was collected during both growth and reproduction stages and until the death of all females in each tank. The experiment lasted nearly 300 days. Temperature differences between tank types were registered during both stages. The optimizing of rearing conditions has allowed for higher growth and a higher amount of cuttlefish available for breeding purposes. A total of 123,751 eggs (in 85 batches) was obtained during this experiment, which is a number that may meet a small scale cuttlefish commercial hatchery facility requirements. The present conditions contributed to a better and predictable reproduction performance in specific 9000L tanks, with values reaching pre-industrial numbers (approximate to 24,000 eggs/tank). Moreover, both the amount of eggs per batch and the overall quality of eggs has increased. Three of these 9000L tanks have an overall consumption of approximate to 38.64 Kg tank(-1), which translates in an investment in feed of approximate to 193 (sic) tank(-1), 8.40 (sic) per cuttlefish and an overall daily tank expense of 1.76 (sic) d(-1).
- The stress response in antarctic fish: HPI modulation, cortisol profiles, interrenal sensitivity, and gene expression of notothenia rossii acclimated to temperature challengesPublication . Guerreiro, Pedro Miguel; Silva, Sandra; Louro, Bruno; Alves, Alexandra C.; Couto, Elsa; Canario, AdelinoThe Antarctic Ocean is one of the most extreme marine environments. Antarctic fishes evolved in stable cold thermal conditions (−1.9 ◦C to 2 ◦C) for roughly 20 million years, displaying structural and functional features resulting from adaptation or inherited from resilient ancestral species. Climate change forecast models show temperatures may increase at a relevant pace. As fish face a warmer future, their physiological ability to adapt is uncertain. We aimed at evaluating the capabilities of the hypothalamus–pituitary–interrenal (HPI) axis in Antarctic fish and show plasma cortisol profiles, expression of key genes, the sensitivity of the ex vivo interrenal tissue, and the responses to known modulators of the HPI axis in temperature-acclimated fish before and after stress. Notothenia rossii were collected from the waters of Admiralty and Maxwell bays, in King George Island, and transferred to an open circuit with ocean-pumped seawater. Upon acclimation, three sets of experiments were performed: (1) eight groups at 2 ◦C were injected with drugs involved in blockage or stimulation of cortisol release/action (saline, cortisol, dexamethasone, metyrapone, spironolactone, mifepristone) and then kept at control or transferred to 6 ◦C and sampled after 36 h; (2) fish at 2 ◦C were exposed to a standard stress test (SST: chasing+netting+1min air exposure), returned to the respective tank and sampled after 1, 4 and 24 h, while one undisturbed group served as control; (3) six groups were acclimated to 2, 5 and 8 ◦C for 10 days when the control group of each temperature was sacrificed. The other group received SST and was sacrificed 90 min after. Plasma and tissue samples were collected for cortisol and stress-related genes, and the interrenal was used in vitro to determine sensitivity to ACTH in a perfusion system with a continuous flow of oxygenated ringers, and 20 min fractions were collected for 240 min. Cortisol was measured via radioimmunoassay, while glucose and lactate were determined using colorimetric kits; gene expression was evaluated by qPCR. Manipulation of the HPI axis revealed that these fish show similar dynamics to those reported in temperate fish but with lower amplitude. After SST, cortisol peaked at 1–4 h and reduced to basal between 24 and 48 h. Temperature influenced the cortisol response to SST. At higher temperatures, cortisol levels in the non-stressed group were as high as in fish subjected to SST. Interrenal cells showed little response to ACTH in warm conditions, suggesting low sensitivity and/or exhaustion. Liver cortisol receptor genes were downregulated, possibly indicating a peripheral desensitization process that parallels HPI. These results show the ability to respond to stress at cold and mild temperatures but important impairments and substantial allostasis in warm or continuously increasing temperatures.