Latin American Journal of Aquatic Research

ABSTRACT In this research, the effect of different productive stages of tilapia (Oreochromis niloticus) in a hyper-intensive aquaculture system on the growth of tomatoes was evaluated. Fish were cultivated in a final density of 80 kg m3 considering three development stages (an average of fingerling of 1.487 g, juvenile of 62 g, and adult of 203.75 g, respectively). The quality of water was measured by determining temperature, pH, electric conductivity, and dissolved oxygen. Biometric data were registered throughout the growth of fish and tomatoes. Results showed that the survival, growth, and health of fish are not affected by the hyper density of culture; as well as the quality water was maintained under acceptable conditions for the development of organisms. Besides, it was obtained that the early productive stages (fingerlings and juveniles) gave the best results for tomato growth. These results suggest using the wastewater from fingerlings and juveniles of a hyper intensive recirculation aquaculture system to produce hydroponic tomato; to achieve sustainable production systems with maximum use of the resources.

ABSTRACT Migrational behavior of anchoveta (Engraulis ringens) in the Northern Humboldt Current System between September 2019 and September 2020 is analyzed. Acoustic, biological, and oceanographic data and information from the several research cruises carried out by the Instituto del Mar del Perú (IMARPE) during this period were considered. The results showed the presence of transitory warm oceanographic events that induced the anchoveta population to make horizontal and vertical migrations in their search for cold conditions, the adult specimens (bigger than 12 cm of total length) retracted near the bottom of the platform being inaccessible to the fishing fleet; after the normalization of environmental conditions, their abundance was accessible to the fishing fleet. Therefore, the fishing activity in the second season of anchoveta fishing in 2019 had a negative impact due to the joint action of environmental events and events of a biological nature (entry of strong recruitment and migration). The anchoveta was preferably found in cold coastal waters that varied in the seasons. In the spring of 2019, it was found in temperatures lower than 22.1°C, in the summer of 2020 at temperatures lower than 23.1°C, and in the winter of 2020 at temperatures lower than 17.2°C; as for, salinity was always found in values lower than 35.2. The strategy of the migratory behavior of the anchoveta concerning its habitat in this period has allowed it to remain in its abundance in the Humboldt Current System, which added to adequate fishing management will allow it to maintain its sustainability.

ABSTRACT Artemia franciscana is one of the most used organisms as live food to larvae of different marine species, so it is important to determine the appropriate food ration to improve its biochemical composition and maintain the nutritional stability of the Artemia. Furthermore, even though light is important in newly hatched nauplii, its effect in the late stages of Artemia have been poorly studied. This study aimed to evaluate the effect of food density (Chaetoceros muelleri microalgae) on the ingestion rate, protein, and lipid content of A. franciscana juveniles exposed and unexposed to light during 6 h. The experiment evaluated six treatments, resulting from combining three densities of C. muelleri as a food: 600,000, 900,000, and 1,200,000 cell mL-1 and two illumination conditions: exposed and unexposed to the light. The ingestion rate was evaluated at 3 and 6 h, while protein and lipid content at the end of the experiment. The highest ingestion rates were observed in the treatment of 900,000 cell mL-1 exposed to light at 3 h (253,118 cell ind-1 h-1) and unexposed to light at 6 h (164,712 cell ind-1 h-1). At the same time, the highest content of lipid (13.52 μg ind-1) and proteins (38.28 μg ind-1) per organism was obtained with the treatment of 900,000 cell mL-1 unexposed to light. There was an interaction between cell density and light since both factors influenced the results of the ingestion rate and lipid content of the juveniles of A. franciscana.

ABSTRACT Haematococcus pluvialis (Chlorophyta) is a microalga with the greatest capacity to generate pure natural astaxanthin with powerful antioxidant properties, through special cysts, in response to disruptions caused by stress conditions. This research tested the design of a prototype for applying artificial light photoperiods controlled by light-emitting diodes on an industrial scale for generating forced stress in H. pluvialis cells during two seasons of the year (winter and spring 2019) in the Coquimbo region in Chile. Three different culture structures were used for the four stages of the alga production cycle. Two containers, A and B, were used for the first and second culture stages, while a raceway (large pool) was used for the third and fourth culture stages. Experiments with four different photoperiods (PP) that represent hours of light:darkness were conducted in two trials (spring 16:8 and winter 18:6) and two for control (spring 11:13 and winter 10:14). In the experiment, an exponential increase of β-carotenoid was achieved, used in human and animal food for its health properties and as a natural colorant in the salmonids industry. Biomass and astaxanthin production under forced stress were measured with physical and chemical variables such as light intensity, temperature, pH, and dissolved oxygen. Results show that the spring culture showed a considerable increase of cysts and, therefore, of astaxanthin reservoirs, reaching a pigment production density of 276 g m-3, with the consequent increase in density of up to 22% more than the control PP.

ABSTRACT This work looks at the antibacterial efficacy of Gracilaria vermiculophylla and Ulva flexuosa aqueous extracts when added to the feed of Penaeus vannamei in an experimental infection with Vibrio parahaemolyticus (M0904AHPND+strain). Results show that the minimum inhibitory concentration (MIC) for both extracts was 50 mg mL-1, with inhibition zones of 18.00 ± 0.60 mm for G. vermiculophylla and 14.00 ± 0.29 mm for U. flexuosa. G. vermiculophylla gave a higher total content of phenolic compounds (10.58 ± 2.31 mg GAE g-1) (gallic acid equivalent) and lower flavonoid content (10.32 ± 0.73 mg QE g-1) in comparison to U. flexuosa, while using ABTS (2,2-diphenyl-1-picrylhydrazyl) and ferric reducing antioxidant power (FRAP) to measure antioxidant capacity showed that G. vermiculophylla gave a better result than U. flexuosa. The challenge with V. parahaemolyticus resulted in 67% survival for organisms fed G. vermiculophylla and 60% for those fed U. flexuosa, resulting in twice the amount of survival as opposed to 30% in the positive control at 24 h post-infection. Histopathological alterations in the hepatopancreas with hemocytic infiltration within the intertubular connective tissue were observed. Also, tubules with severe cell detachment and tubular atrophy were detected in the positive control organisms, and organisms treated with macroalgae only had vermiform structures in the tubular lumen, cell detachment, and infiltration hemolymph in intertubular connective tissue. According to the analysis of the studied variables, it can be concluded that the aqueous extracts of these macroalgae are a promising alternative for V. parahaemolyticus (M0904AHPND+strain) control in shrimp culture.