Latin American Journal of Aquatic Research

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Latin American Journal of Aquatic Research

  • Environmental stressor induces morphological alterations in zooplankton
    el mayo 22, 2022 a las 11:39 pm

    ABSTRACT Morphological alterations in zooplankton are induced by exposure to hazardous materials in the environment. These alterations in the body are excellent indicators of adverse effects at the (sub) individual and population levels. These changes might be undetectable within a population in the first generation; however, it was recently documented that alterations are more frequent in the subsequent generations. Because of this, we revised scientific literature that reported malformations in cladocerans, copepods, oligochaetes, and rotifers caused by diverse toxicants when organisms were exposed either in the laboratory or in natural conditions. From an environmental perspective, we focused on the importance of morphological alterations in zooplankton, the most likely causes, and their consequences. Furthermore, the present article shows that alterations of the normal morphology could be used as consistent biomarkers, but further research requires discriminating the influence of natural behavior and the consequences of exposure to toxic compounds.

  • Effect of mushroom (Pleurotus djamor var. roseus) meal as feed supplemented on the hematological responses and growth performance of Nile tilapia (Oreochromis niloticus) fingerlings
    el mayo 22, 2022 a las 11:39 pm

    ABSTRACT This study aimed to evaluate the effects of mushroom meal supplementation, Pleurotus djamor var. roseus (Pd), on the diet of Nile tilapia (Oreochromis niloticus), on hematological parameters and growth performance for 60 days. Nile tilapia fingerlings (3.23 ± 0.19 g) were fed with three experimental diets based on the mushroom meal in different percentages: diet 0% control (MM0), diet 15% (MM15), diet 20% (MM20) and diet 25% (MM25). Blood samples from the fish of all treatments were collected at the start of the experiment (day 0), 30 and 60 days. The weight and size of the fish were determined every 15 days (0, 15, 30, 45 and 60 days). The results showed a significant dose-dependent increase in the levels of erythrocytes count and leukocytes count. The groups that showed significant differences in the basal value and the final control result were hematocrit, hemoglobin, and lymphocyte. An increase in lymphocytes proportion and a decrease in neutrophils were found, which was related to the immune response of fish fed the diet. The highest levels of leukocytes, lymphocytes, and low neutrophils were presented in the diet with 15 and 20% (P < 0.05). The growth (weight gain and specific growth rate) of fish fed MM15 and MM20 of Pd in the diet was higher than the control group (P > 0.05). Dietary supplementation (15 and 20%) improved hematological and defense blood cells, as well as the growth of tilapia.

  • Effect of pond fertilization on growth performance of pirarucu (Arapaima gigas) during grow-out phase
    el mayo 22, 2022 a las 11:39 pm

    ABSTRACT. Fertilization of aquaculture ponds has been pointed out as an efficient practice to improve fish feed conversion and growth performance. In this way, the present study aimed to assess the effect of pond fertilization on the growth performance, body composition, and water quality of juvenile pirarucu Arapaima gigas reared in earthen ponds (600 m2) during the grow-out phase. Two fertilized and two non-fertilized ponds were stocked with 208 juvenile pirarucus (19.9 ± 3.6 g and 15.0 ± 0.9 cm) and reared for 100 days. All four ponds were limed before the study. Ponds were fertilized before fish were stocked and weekly until the end of the experiment, and fish offered feed until apparent satiation. Pirarucu reared in fertilized ponds presented higher final weight (20%) and biomass (19%), further to lower feed intake and feed conversion rate (1.31) than fish reared in non-fertilized ponds (1.61). Pond fertilization did not affect the fish coefficient of variation, which was reduced over the culture cycle. The body composition of fish reared in fertilized ponds presented higher water content, protein, and energy retention rates and lowered crude fat and energy. Fertilized ponds presented lower transparency levels and higher pH from the 50th day of culture, whereas ammonia concentration was higher in the fertilized ponds in the first 25 days. Therefore, pond fertilization is a recommended practice for pirarucu during the grow-out phase.

  • Effect of sea surface temperature on the growth performance of the thread herring Opisthonema libertate (Günther, 1868) in the southern Gulf of California
    el mayo 22, 2022 a las 11:39 pm

    ABSTRACT. The present study assessed the effect of sea surface temperature (SST) on the individual growth performance of the thread herring Opisthonema libertate in the southern Gulf of California. For the period from 1988 to 2017, based on monthly length-frequency information, the von Bertalanffy equation's growth parameters (L∞, K, and t0) were estimated annually. Annual values of the growth performance index Φ' were inversely related to the SST (P < 0.05). The values of K and L∞ corresponding to the modal value of the distribution of Φ' were taken as representative of the species, and the temperature change pattern function over time was incorporated as a forcing of the growth coefficient, K, in the growth model. Thus, it was possible to represent the yearly effect of SST on growth performance. These estimates are considered of great interest for future research because they directly influence the variability in allocating the number of individuals at different ages.

  • Effect of the shrimp farming wastes as co-feed on growth performance and digestibility of juvenile grey mullet, Mugil cephalus
    el mayo 22, 2022 a las 11:39 pm

    ABSTRACT. A feeding trial was carried out to evaluate the utilization of residual nutrients from shrimp farming wastes (SFW) as co-feed in juvenile grey mullets Mugil cephalus. Four treatments were designed to offer shrimp farming wastes in different proportions as feed. The first treatment (control) consisted of feeding the entire daily portion with only commercial feed for marine fish (SFW0). The remaining treatments replaced the daily feed with shrimp farming wastes in 33, 66, and 100%, respectively, treatments SWF33, SWF67, and SWF100. Feed was offered daily as 4% of the grey mullet total biomass at each experimental tank. Results showed that final weight, weight gain, specific growth rate, relative weight gain, and thermal growth coefficient were reduced in the fish when the proportion of SFW in their feed was increased. However, the fish showed a digestive capacity that allowed them to use residual nutrients in a ratio up to 66%, increasing their initial weight by up to 25%. The increase of shrimp farming waste as feed negatively affected the whole-body proximal composition. The digestibility results showed that the fish could digest up to 41% of the shrimp farming waste protein. Results suggest that juvenile grey mullets are capable of utilizing residual nutrients from shrimp farming waste. However, it is necessary to complement an alternative feed source to induce an optimal growth performance for the juvenile grey mullets. It is also recommended that mullets be fed with formulated feed to meet their nutritional requirements to maintain the protein and lipid content of the whole body under culture conditions.

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Mauricio Eberle Morales

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