Latin American Journal of Aquatic Research

Aurantiochytrium sp. and Nannochloropsis spp. meals as substitutes for fish oil in practical diets for Pacific white shrimp Penaeus vannamei

Aurantiochytrium sp. and Nannochloropsis spp. meals as substitutes for fish oil in practical diets for Pacific white shrimp Penaeus vannamei This study aimed to evaluate the use of microalgae meal (Aurantiochytrium sp. and Nannochloropsis spp.) as a substitute for fish oil in the diet of shrimp Penaeus vannamei reared in a clear water system. In the diet of these animals, the concentration of fish oil decreased as microalgae meal was inserted, and these were used in five different substitutions: 0, 25, 50, 75, and 100%. The treatments were carried out in triplicate, and after 49 days of cultivation, the zootechnical parameters and the composition of fatty acids in the animals' muscles were analyzed. In zootechnical performance, the shrimp obtained an average final weight of 16.59 ± 0.3 g, and the growth was approximately 1.89 ± 0.30 g week-1. In addition, feed conversion was, on average, 1.47 ± 0.28, and survival was greater than 97%. However, no significant difference was observed in these parameters. Regardless of the levels of fish oil replacement by microalgae meal, the composition of fatty acids in the shrimp muscle was ensured, as well as their quantity within groups, such as n-3 and n-6 polyunsaturated fatty acids. Thus, with the results obtained in the present study, it is suggested that it is possible to formulate a high-performance diet without any ingredients of marine origin (fish oil or fish meal), contributing to aquaculture's sustainability.

Performance of high-resolution MUR satellite sea surface temperature data as a proxy for near-surface in situ temperatures on neotropical reefs

Performance of high-resolution MUR satellite sea surface temperature data as a proxy for near-surface in situ temperatures on neotropical reefs As ocean temperatures increase, so does the need for accurate, regular, and widespread temperature data. This is especially important for researchers studying corals, which can be pushed over their bleaching thresholds by small, sustained changes in water temperature. Satellite data products offer longitudinal estimates of sea surface temperature (SST) taken at regular intervals without the ongoing costs and geospatial limits associated with underwater temperature loggers. However, previous work indicates satellite data are sometimes characterized by significant temperature biases, particularly in stratified coastal waters. Here, we compared the foundation sea surface temperature (fSST) estimated from a highly processed, gridded satellite data set (GHRSST MUR L4 Global SST) to in situ temperature (IST) data collected from coral reef habitats in the top 20 m of the water column at 19 sites in Panama. Comparisons between Pacific and Caribbean coasts and between upwelling and non-upwelling seasons provide a robust test of the utility of this product to estimate subsurface temperatures. The mean differences between fSST and IST show that MUR fSST accurately reflects temperatures at shallow (<9 m) depths on the Caribbean coast (mean bias ≤0.55°C ± standard error (SE) 0.01°C) and during the non-upwelling season on the Pacific coast (mean bias ≤0.26°C ± SE 0.03°C). MUR fSST poorly reflects IST during the Pacific upwelling season, especially at sites 12 m and deeper. In such cases, 66% of satellite estimates deviated from ISTs by >1°C. Our findings underscore how highly processed SST data products should be ground-truthed before being used as a substitute for IST, especially in upwelling areas.

The coloration of Neocaridina davidi (Bouvier, 1904) (Caridea, Atydae) fed with live microalgae Haematococcus pluvialis and the cyanobacteria Spirulina (Arthrospira) platensis

The coloration of Neocaridina davidi (Bouvier, 1904) (Caridea, Atydae) fed with live microalgae Haematococcus pluvialis and the cyanobacteria Spirulina (Arthrospira) platensis Haematococcus pluvialis synthesizes and accumulates astaxanthins, while Spirulina (Arthrospira) platensis produces phycocyanins. The ornamental shrimp Neocaridina davidi is commercially important for its variety and intensity of coloration. We evaluate the effect on the coloration of N. davidi by consuming H. pluvialis and S. platensis as a food supplement to preserve their nutritional quality. H. pluvialis was subjected to stress to obtain aplanospores with astaxanthin. Live microalgae were included in gelled spheres to provide them as a supplement to three-day-old N. davidi juveniles with different phenotypes: wild (NdW), red (NdR), and blue (NdB). The experiment involved the commercial food supply and spheres with or without microalgae for 31 days. Chromatophores present in the uropod of each phenotype were examined, their number and expansion estimated, and the area covered by optical density (OD). Results show that H. pluvialis reached a greater astaxanthin accumulation on day 30. The coloration of the NdR and NdB phenotypes improved by consuming microalgae, increasing the OD in the uropod. NdB phenotype showed better coloration when consuming S. platensis (56.2%), while the NdR phenotype was more favored when consuming H. pluvialis (74.2%). The chromatophores expanded their area by doubling in the NdR and NdB phenotypes, where H. pluvialis increased its intensity four times in NdR. The number of chromatophores was significant only in NdR with S. platensis. In conclusion, gelling is a viable method to preserve the nutritional quality of live microalgae and transfer bioactive compounds that improve the coloration of N. davidi.

First record of the bluntnose sixgill shark Hexanchus griseus (Bonnaterre, 1788) in the Guatemalan Caribbean Sea

First record of the bluntnose sixgill shark Hexanchus griseus (Bonnaterre, 1788) in the Guatemalan Caribbean Sea The Guatemalan Caribbean has a deepwater fishing area close to the shore around the Cayman Trench. This study reports the first record of the bluntnose sixgill shark (Hexanchus griseus) from this fishing area. Fishery-independent surveys using longlines at ~430-465 m depth, ~11 km northeast of El Quetzalito fishing village, were conducted in 2022 and 2023. Two bluntnose sixgill sharks were captured during these surveys. The sharks were females with total lengths of 300 and 310 cm, with morphological characteristics consistent with this species. These are the first confirmed records of bluntnose sixgill sharks in the western Caribbean Sea. Expanding coastal fisheries to deeper waters presents an emerging threat to deep-sea chondrichthyans in the region. Therefore, periodic fisheries monitoring is needed to estimate their vulnerability to fishing pressure.