Management and preservation of aquatic environments are essential for their productivity and the maintenance of aquatic life. This study aims to characterize the trophic state of Toho-Todougba lagoon complex which has been subject for several years, to an intense fish production in cages. For this purpose, physico-chemical parameters were measured from June 2019 to May 2020 as well as chlorophyll-α, phosphorus and nitrogen. The trophic characterization indices were calculated basedo n Carlson (1977), Burns and Bryers (2000), Neverova-Dziopak and Kowalewski (2018), Primpas et al. (2010) and CCME-WQI (2001). It appears that the temperature (29°C), dissolved oxygen (3.19 mg.L -1 to 4.33 mg.L -1 ) and pH (6.66 to 7.31) are those characteristic of tropical lake environments. The production parameters revealed that the chlorophyll-α concentration varies from 0.19 to 37 mg.L -1 (stations and months combined). The concentration of phosphorus ranged from 0.02 to 0.42 mg.L -1 while nitrogen varied from 1.91 to 4.03 mg.L -1 . Only nitrogen is not in critical proportion for the ecosystem. It should be noted that with the exception of the Carlson index, all other indices revealed that the ecosystem is in a state of advanced eutrophication with a tendency to hyper-trophication according to the eutrophication index of Primpas et al. (2010). Consequently, Toho-Todougba lagoon complex is eutrophic and requires adequate measures for its restoration despite its good health revealed by the physico-chemical parameters.
The fishery of Omani sea cucumber, Holothuria scabra , is limited so far to the Mahout Bay in Al Wusta governorate. This fishery supports an uncertain number of fishermen ranging from 100 to 150. This fishery is not well-studied and has no current management program. In order to prepare a management strategy, the government has suspended this fishery for 2 years from March 2018 to March 2021. Apart from presenting a thorough review on the sea cucumber fishery in Oman, the current work presents a detailed analysis of the length–weight relationship, sex ratio, and condition factor of the H. scabra collected from four different areas during the period February-May 2019. Based on the results, the females were longer than males, that is 226±33.4 and 221±37.8 mm, respectively. The overall sex ratio of the entire/pooled sample was 0.49 which was not different from the anticipated theoretical sex ratio of 0.5. The mean K n and the empirical weight–length equations for the total sample were between 0.12±0.01 and 1.0±0.16, and W =0.03L 1.6 , respectively.
Otolith shape and morphology are used to identify fish species and population stocks. The aim of this study was to distinguish the Lethrinus lentjan (Lacepede, 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).
This work is a study of growth aspects and mortality of the Atlantic chub mackerel, Scomber colia, from the Mediterranean Moroccan coast. A total of 845 specimens were collected from commercial catches in M’diq Bay, whose total length ranged between 16.4 and 35.9 cm. The length-weight relationship was W = 0.0019 TL 3.4527 (r = 0.97) for the whole population. The Atlantic chub mackerel displays positive allometric growth. Otolith edge analysis indicated that opaque zones were formed between April and September and translucent ones during the remaining months of the year. The oldest individuals in the sample were 5 years old for both sexes. Von Bertalanffy growth parameters estimated for this species were: L ∞ = 37.30 cm, k = 0.26 year -1 and t 0 = - 2.19 year. The difference in growth between sexes is not significant. The estimated natural mortality was 0.59 per year.
Characteristics of the Lecane (Rotifera) community in psammon in Central Coast Vietnam were investigated. A total of 50 taxa were identified in samples collected at hygropsammon zones of temporary pools, contributing 4 new species to rotifers’ record of Vietnam. Psammonxenic species accounted for the largest percentage of Lecane community with 82%, followed by psammophiles (12%) and psammonbionts (6%). Influences of some environmental factors on the distribution of psammic lecanids were also observed. This group of organisms showed a slight tendency towards sand with grain sizes larger than 125 µm. Besides, other abiotic factors including pH, total phosphorus (TP) and total dissolved solids (TDS) were also found to significantly related to the distribution of some common Lecane species.
Lobocheilos falcifer is a rare and vulnerable freshwater fish species from Java, Indonesia and currently listed as Vulnerable (VU) within the IUCN Red List. In 2019, three specimens of L. falcifer were collected and photographed on Rawa Pening Lake, Semarang Regency, Central Java Province and Solo River, Karanganyar Regency, Central Java Province as two new localities for this species, extending its distribution in about 80 km to southeast. We also provided the morphological data of this species as well.
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 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 humen. 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 from abandoned land 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 was 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. The first report of an Enterobacter sp. strain which can use 2, 2-DCP as its 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.
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 Oueme 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.
Seeds of Phaseolus vulgaris L. and Pisum sativum were planted in separated pots, then these pots divided into two groups, each group divided into four subgroups. Four different wastewater were used to irrigate the treatments. The results showed the effects induced by irrigated wastewater on P. vulgaris L. and P. sativum. The degree of water salinity induced increasing SOD, protein content and the area of xylem elements, but reduced chlorophyll-α in P. vulgaris . The CAT, protein and chlorophyll-α were increased in in P. sativum as a result to salinity which also reduces the area of xylem elements.
The main objective of this study was to examine the growth, mortality, and exploitation rate of Chloroscombrus chrysurus from the continental shelf of Ghana, West Africa between July 2018 and June 2019. This study provided results on fishery dynamics parameters to contribute to estimating the stock assessment of these fish species. Monthly length-frequency data were collected from 697 samples and analyzed using fisheries models fitted in TropFish R. The von Bertalanffy growth parameters were utilized to analyze the population dynamics of these species using ELEFAN Simulating Annealing. The estimated asymptotic total length (L ∞ ), coefficient of growth (K), and growth performance index (Φ′) was 24.9 cm, 0.84 year -1, and 2.72, respectively, with a Response surface (Rn) value of 0.79. The total mortality (Z), natural mortality (M), and fishing mortality (F) rates C. chrysurus from the continental shelf of Ghana were 3.27 year -1 , 1.31 year -1 , and 1.96 year -1 , respectively. The exploitation rate (E) estimated was above the optimum level of 0.5 which indicates that the species is overexploited. Based on the Emsy (0.69) value, analyses show that the exploitation rate has exceeded the sustainable limit and hence the need for proper fisheries management measures.
Blood biochemical parameters are important factors that can show the changes in health offering critical feedback on physiological condition of fish. In the present study, we examined a comparative study on the blood biochemical parameters in mature male and female goldfish, Carassius auratus . Plasma samples of 72 male and female goldfish that have been kept at 24°C for 30 days were analyzed and their biochemical parameters levels were determined. There were significant differences in all measured parameters between genders so that, maximum concentrations of the glucose (73.45±0.68 mg/dl) and calcium (8.32±0.05 mg/dl) were found in female fish, while the highest levels of the total protein (3.14±0.01 g/dl), cholesterol (281.65±3.19 mg/dl) and triglyceride (428.31±1.17 mg/dl) were measured in males. Based on the results, the plasma biochemical parameters changes vary considerably between male and female goldfish.
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/10 6 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.
This study investigated the immuno-toxicological effect of the insecticide fipronil at sublethal concentration (10% of LC 50 ) and the potential ameliorative effects of dietary microbial levan in Cyprinus carpio fry. Fish were randomly distributed into five treatments in triplicate for 60 days. Five different treatment groups were: levan control L 0 F 0 (basal feed + 0% levan without exposure to fipronil), pesticide control L 0 F (basal feed + 0% levan with exposure to fipronil), other three dietary supplemented groups exposed to fipronil with different inclusion levels of levan at 0.25% (L 0.25 F), 0.50% (L 0.50 F) and 0.75% (L 0.75 F), respectively. The results revealed that feeding common carp with 0.75% dietary levan significantly reduced ( P <0.05) glutathione-S-transferase and glutathione peroxidase levels in various tissues. Lipid peroxidation and heat shock protein level was significantly ( P <0.05) reduced with supplementation of levan at 0.75% compared to other groups. Higher glycogen content was observed in high levan fed groups. Although fipronil exposure had no signficiant effect on lipid profile levels, dietary levan supplementation decreased lipid profile level in the fish exposed to fipronil stress. Total immunoglobulin and myeloperoxidase content of common carp showed an increasing trend with the concomitant increase in the level of levan administration in the diet. Overall, results revlealed that microbial levan at 0.75% in the fipronil induced C. carpio fry mitigated the stress due to its potent nutraceutical properties, thus presenting a promising immuno-additive for aquaculture.
Procambarus clarkii is a native species of Central America, but strongly invasive in many regions of the world. An investigation on the red swamp crayfish was carried out to obtain more information about its population dynamics in the Tiber River, in Central Italy. A total of 900 individuals, both males and females, were sampled within two different campaigns (2017 and 2019) aimed at collecting biometric data. A strong fishing effort was deployed (more than 100 nets set), to guarantee a large and randomized number of samples. The crayfish populations were grouped into seven different cohorts, according to Bhattacharya’s method. The population showed a balanced sex ratio, the average cephalothorax length was 42.52 mm, with the most represented size class between 40-50 mm. K and L ∞ , as well as the growth parameter index (O), the mortality rate (Z), and longevity value (t max ), were calculated. K and O values resulted very high, showing an impressive growth rate in the study area; t max ranged from 4 to 5 years, L ∞ values were lower compared with other studies (58.0-59.0 mm), while Z was very high for this population (4.2-4.5 year). The results revealed that crayfish population dynamics can be complex and vary depending on habitat type, available trophic resource and competition.
The squeaker, Synodontis schall dominates the Mochokid fish sub-community in Niger River in Northern Benin and shows a great economic and commercial importance. The diet of S. schall has been analysed to evaluate the food habit and resource utilization in this regional River. Fish samplings were made monthly from February 2015 to July 2016 using unbaited longlines and traps, seines and experimental gillnets. The results indicated that S. schall is an omnivore foraging in benthic and pelagic habitats with diet dominated by aquatic insects (34.32%), sand particles (18.768%), macrophytes (13.415%), seeds (8.549%), roots (8.319%), detritus (5.344%), mollusks (1.204%) and phytoplankton (0.6255%). The omnivore food habit depicted was also shown by the ecomorphological analysis mainly the relative gut length (GL/SL) varying between 0.8 and 5. The species showed high diet flexibility with high niche breadth ranging between 1.86 and 5.74. Synodontis schall exhibited an ontogenetic diet shift that was also confirmed by Pianka’s diet overlap indexes ranging between O jk =0.54-0.93. The conservation and the sustainable fisheries exploitation of S. schall require the reinforcement of fishing regulation, habitat protection and ecosystem follow-up.
The olfactory structure of Xenentodon cancila (Hamilton, 1822) were explored by advancement in microtomy, staining and ultrastructural practices. The unique feature of the olfactory system was that the olfactory cavity, an open groove with an obtruding sole lamella, no rosette like organization. The lamella was constituted of the central core, lined on both sides by well-organized epithelium. The central core usually consisted of connective tissue fibres and blood capillaries. The epithelium exhibited compact cellular distribution and made up of receptor cells, supporting cells, lymphatic cells, inner most basal cells and almost never mucous cells. Morphologically specific two types of receptor neurons were recognizable: ciliated and microvillous, comprising sensory terminals. The cellular constitution of olfactory mucosa was explained with olfactory sensitivity of the fish necessitated.
Replacement of fish meal by cost effective and sustainable plant resources in the formulation of feed for fish is a viable option to alleviate the current crisis in fish feed industries arising due to high cost and non-availability of fish meal. The present research was aimed to evaluate if fermented leaf meal of the aquatic plant Ipomoea aquatica could be used as a fish meal alternative in the formulation of feed for the catfish Heteropneustes fossilis . Fresh green leaves of I. aquatica were sun dried and finely ground to make Ipomea leaf meal (ILM), which was then fermented for 12 days by the phytase producing bacteria Stenotrophomonas maltophilia strain KUAKSP1 (GenBank Accession No. KY790423) isolated from rumen of goat. Four iso-proteinous, iso-lipidous and iso-energetic feeds were formulated by replacing 0, 25, 50 and 75% of fish meal by the fermented Ipomoea leaf meal (FILM). Protein digestibility of the feeds was evaluated within 12 days in an indoor experiment in glass aquaria and growth performance of the fish was evaluated after 8 weeks rearing in outdoor cement tanks. H. fossilis grew better on FILM supplemented feed as compared to fish meal based control feed. Maximum apparent protein digestibility (APD) of the feed, maximum weight gain (WG) and specific growth rate (SGR) and minimum FCR of the fish were found in 50% replacement group. However, crude protein (CP) and crude lipid (CL) deposition in the muscle of the fish and activity of protease in the gut was higher in 25% replacement group. It is concluded that H. fossilis accepts and grows well on the plant based FILM supplemented feed. For better growth management of the fish, incorporation of FILM in the feed should be restricted to 25 to 50% of fish meal.
Blood cockles, Anadara granosa (Linnaeus, 1758), were collected from the aquaculture grounds (4 stations) of the Selangor coast, Malaysia, and the water quality (water temperature, salinity, dissolved oxygen, turbidity, and chlorophyll a ) was measured from September 2011 to June 2013. At all stations, the water temperature fluctuated around 30℃. At station C, located at the mouth of the Selangor River, the salinity was occasionally lower than 20 PSU. However, the salinity of the other stations fluctuated around 30 PSU. In addition, at all stations, the content of dissolved oxygen generally fluctuated around 3 mg.L -1 or above, and the turbidity changed irregularly, sometimes exceeding 300 Forumajin Turbidity Units. The chlorophyll a content fluctuated mainly ranging 4-20 µg.L -1 at all stations, and values above 20 µg.L -1 were occasionally observed. The phytopigment content, a food availability indicator, in the digestive gland tissue of the blood cockles collected from all stations fluctuated ranging 30-770 µg.g -1 . However, there was no proportional correlation between phytopigment content in the digestive gland and chlorophyll a content at all stations. Therefore, even in a high chlorophyll a content (over 20 µg.L -1 ) environment, the accumulated phytopigment in the digestive gland was around 290 µg.g -1 . In general, these results indicated the cockles were eating a sufficient amount of foods (organic materials including phytoplankton) all year round during the study period. And, the food availability environment in the aquaculture grounds of the Selangor coast was estimated sufficient to grow the blood cockle.
