International Journal of Aquatic Biology
Volume:9 Issue: 3, Jun 2021

The current study aimed to determine parameters and conditions for successful reproduction of Macrobrachium macrobrachion (Herklots, 1851) in a controlled medium and describing its embryonic development. A total of 122 adult specimens were collected from the delta of Ouémé River and stored in polyethylene tanks with 1:2 male-female sex ratio. This broodstock was fed on pelleted food (Biomar Efico) once a day. For the embryogeny monitoring, eggs were sampled each hour through the first two days after spawning and then every 2 hours till hatching. Spawning happened at a mean temperature, dissolved oxygen concentration and pH of 27.80±0.56°C, 5.83±0.45 mg/L and 7.41±0.34, respectively. The eggs incubation meantime was 12±1 days with nine main embryonic development stages. Hatching lasted on the average 21.00±1.94 h and led to larvae with a mean size of 2.30±0.90 mm. Mean fecundity was 13062.4±5489.93 eggs and 14715.2±6108 eggs, respectively for the first and second seasons with a highly significant difference between them. The best hatching rates were obtained with salinities equal to 2 and 4‰. The results constitute the first database for larval breeding of M. macrobrachion species.

Otolith shape and morphology are used to identify fish species and population stocks. The aim of this study was to distinguish the Lethrinus lentjan (Lacepède, 1802) and L. microdon (Valenciennes, 1830) (family: Lethrinidae) using otolith shape. The analyses apply the ShapeR package in R which enables to extract the outline and otolith morphology from images and for statistical examining of individual variation. Otoliths of 165 individuals from the two Lethrinus species were collected during 2019 and 2020. The wavelet levels were examined by using 6 wavelets to collect 63 coefficients. The regression between width and fish length were b = -0.03 (t = 2.6, P = 0.01) for L. lentjan and was significantly different (t = 2.120, P = 0.036) for L. microdon (b = 0.018).

The marine Copepoda species Oithona nana, is considered as one of the most Copepoda species that successfully mass cultured in marine hatcheries. This study investigated the effects of four feed diets (soybean, yeast, rice bran, and corn starch) on the population growth, growth rate, population composition, fecundity, and fatty acid composition of Copepoda, O. nana. The experiment was continued for 15 days and the copepods were fed on four feed diets with concentration of 1 g/106 individual/day. The results found that O. nana fed on corn starch showed the highest significant population growth (9067 Individual/L) and population growth rate (0.735). For nutritional value, copepods fed on rice bran were detected to have the highest content of monounsaturated fatty acid (MUFA), polyunsaturated fatty acids (PUFA), the lowest saturated fatty acids/unsaturated fatty acids ratio (SFA/UFA ratio) and the lowest SFA. More importantly, the rice bran diet was the only diet that showed eicosapentaenoic acid (EPA; C20:5ω3). Moreover, copepods fed on rice bran showed the highest significant female fecundity (8.33 egg/female), copepodite and nauplii percentages (33.27 and 32.65%, respectively). Finally, regarding to the quantity, corn starch is the most suitable diet for mass culturing O. nana, while, regarding to the quality, rice bran enhances the nutritional value and fecundity of the Calanoida Copepoda O. nana.

In this work, we assessed micro-habitat's influence on the distribution of macroinvertebrates in lake Ziga in Burkina Faso from July to December 2016. The water quality variables were measured in situ and the macroinvertebrates were collected with a hand net. The organisms were identified to the lower taxonomic resolution as possible. The results show that the temperature is globally warm, characteristic of tropical area, with a good oxygen content and pH close to neutral. We found five micro-habitats, mainly dominated by fine substrates (32.5%) and aquatic plants (25.83%). The stone, roots and dead woods represented less than 20%. In total, 3,773 individuals of macroinvertebrates were collected. These individuals belong to 33 taxa and three classes. The insects class is the most abundant (88.22%) and the most diversified (24 taxa, 72.72%). The highest taxonomic richness is observed in aquatic plants and root zones. The diversity and density of the macroinvertebrate community varies according to micro-habitats but not according to the size of their surface area. The results showed that coleopterans and hemipterans were strongly and positively correlated to transparency and conductivity (adjusted r>60%, P<0.05). In the local area, the results showed that macroinvertebrates' diversity and distribution are more linked to habitat availability. Our findings reveal a good habitat condition of the lake, and can be served as reference site and hostpot of aquatic biodiversity in the area.

Sailfin armoured catfish (Pterygoplichthys spp.), an alien invasive species of family Loricariidae has invaded extensively in wastewater-fed large aquaculture ponds (locally called ‘bheries’) of East Kolkata Wetlands (EKW), West Bengal, India. As there is no viable controlling method at present, commonly these fishes are removed by different physical methods and discarded. In the present study, we investigated the effectiveness and suitability of different in-practice Pterygoplichthys spp. control methods, based on on-field sampling, biological and behavioural study of the fish and also response analysis of the stakeholder’s of EKW. The results indicate that in-practice eradication efforts, like ‘repeated seine netting’ with or without removal of Eichhornia sheath of the pond periphery and ‘dewatering of pond’ aiming to reduce or eradicate Pterygoplichthys spp., are not fully effective, because of the capture avoidance ability and burrowing habit of these fishes. We found deep and branching burrows of Pterygoplichthys spp. in aquaculture ponds of EKW, with maximum burrow depth of 58 cm, and water in that burrows even after 12 days of dewatering. Hence, it is suggested stakeholders to keep dewatered pond exposed to sunlight for at least four weeks or above to ensure complete water-out from the burrows in which Pterygoplichthys spp. take shelter or lay their eggs. ‘Multilayer bamboo fencing’ or ‘combination of bamboo fencing and net barrier’ use by the stakeholders of EKW to prevent intrusion or re-intrusion of Pterygoplichthys spp. were found only partially effective, because of the capability of these fishes to damage net-blocking through their hard dorsal and pectoral spines or entry through the holes dug across the barrier in beneath or banks of the sewage intake channel. Based on learning on the biological and behavioural characteristics of Pterygoplichthys spp., we then suggested a modified version of barrier to the stakeholder’s of EKW, incorporating a sewage feeder pipeline, a concrete collection chamber with size separation arrangement made of hard materials like wire mesh and a dam of specific dimensions across the channel, for effective prevention of intrusion of these fishes in their aquaculture bheries.

The trend of capture fishery and aquaculture production in Iran shows an ascending trend. An estimate of future production may be useful for management purposes and providing some clues about the effectiveness of the current plans to reach the goals. We used the data provided by the Food and Agricultural Organization of the United Nation (FAO) to model the time series of the production of aquatics in both sectors. The data covered the years 1980-2018. We predicted the production of aquatics until 2025 using autoregressive integrated moving average models. Several techniques were used to estimate the parameters of the model. However, searching the all possible values of the parameters provided the model with the best predictability. According to the selected model, the production of capture fishery will have ascending trends and increase to 1,513,533 tons in 2025. Aquaculture production will also have an increasing trend, however, the rate of change will be lower than that of the capture fishery. Aquaculture production will reach to 552944 tons in 2025. The forecast is based on the assumption that the rate of changes in the development of capture fishery and aquaculture will remain in the present status. Sudden changes in management practice or environmental conditions may have a remarkable influence on future production.

The widespread use of herbicides containing 2,2-dichloropropionic acid (2,2-DCP) as a recalcitrant halogen compound poses significant environmental risks and can be harmful for human. Consequently, it is important that the bio-based detoxification method is developed in an environmental manner. This study was aimed to isolate and identify a possible degradation 2,2-DCP bacterial strain as the sole source of carbon. A bacterial dehalogenase producing 2,2-DCP was isolated named as WM. The WM strain was shown to have 98% sequence identity and characteristics similar to Enterobacter sp. based on 16s rRNA analysis, biochemical and morphological tests. Phylogenic analysis showed that the WM strain is Enterobacter sp.. In media with 20 mM 3CP, the bacteria were well growing at 37°C, although an optimal chloride ion release was 0.48 μmol Cl/mL. Our finding is first report of an Enterobacter sp. strain which can use 2, 2-DCP as sole carbon source in a competent manner.

Growth is a concept that includes social, economic and physical sub-processes and it also shows itself in the field of fisheries. It is extremely important to obtain the appropriate mathematical model for growth for aquatic species. The growth modelling for the aquatic species contains the phenomena of bio-diversity, formation and population dynamics of aquatic species or stock estimation for the creature. And this study aims to design and implement a new mathematical model for growth process for aquatic species as Generalized Modified Levakovic Growth (GLM) model.