International Journal of Aquatic Biology
Volume:10 Issue: 4, Aug 2022

Microplastics (MPs) are one of the biggest environmental problems threatening aquatic life. The accumulation of MPs in the body of aquatic animals can play a role in transferring these pollutants into the food chain. These pollutants can significantly affect the physiology of aquatic animals. In this study, the bioaccumulation capability of MPs in the body of freshwater crayfish,Astacus leptodactylushas been evaluated. For this purpose, crayfish were exposed to 0, 500, and1000 μg L-1of polyethylene MPs (PE-MPs) for 28 days. Then, the accumulation of MPs in hemolymph, hepatopancreas, and intestine of crabs was investigated by Fourier transform infrared spectroscopy (FTIR). Bioaccumulation of PE-MPs in the hemolymph, hepatopancreas, and intestines was observed in the crayfish exposed to PE-MPs. This study showed that FTIR is a suitable method for identifying and measuring MPs in aquatic organisms.

Artemiais widely used as an initial food forlarval andjuvenile fish in aquaculture facilities around the world. However, several lines of research have strongly suggested that Artemialarvae may carry opportunistic pathogenssuch as Listonella anguillarum, thereby serving asa source of infection of fish. In the present study, we investigated the dynamics of the culturable microflora of Artemiareared under laboratory conditions, with the goal ofunderstandingthe risk of opportunistic infection mediated by this animal.After hatching decapsulated cysts of A.franciscana,the larvae were reared for an additional 27 daysto examine, usingthe culture-dependent method, the culturable microflora of the rearing water and of washed Artemia.The results showed that Vibrionaceae, Flavobacteriaceae, Pseudoalteromonadaceae, Alteromonadaceae and Rhodobacteriaceae accounted for8.3-35.8% of the rearing waterisolates. In contrast,Vibrionaceae dominated in Artemiaisolates, accounting for 79.2% of the flora. However, Vibrionaceae were not detected in either decapsulated or undecapsulated cysts, or in the algal concentrates used as feed, suggesting that Vibrionaceae is not indigenous to Artemiacysts and instead is derived primarily from natural seawater.These results strongly suggest that hatching and rearing live diets such as Artemiaunder sanitary conditions may reduce theriskof opportunistic infection.

The present research work aimed to investigate the unexplored information about mating strategies and reproductive potential of two euryhaline cyclopoid species Apocyclops dengizicus and A. royi. Laboratory experiments on mating strategy and reproductive aspects such as the efficacy of females under different mating conditions, the reproductive potential of males, mating frequency, and the effect of starvation on survival and reproductive potential, were conducted and documented. The once-mated female and females pairing continuously with males favored higher reproductive potential. In the present study, the mate-pursuing males prefers to copulate with mature virgin females. The older female was unable to produce eggs even after the sperm discharge. The lifespan of both the Apocyclopsspecies under different states of mating and unmated conditions showed considerable variation.Apocyclops dengizicusproduced 7.92±0.57 pairs of spermatophores, whileA. royiextruded 13.32±0.99 pairs of spermatophores during its lifespan. The results were analyzed and inferred; thus high throughput was applied to reveal the understudied topics of these Apocyclopsspecies to add considerable knowledge about its reproductive biology.

In the present study, Cypridopsis vidua(Muller, 1776), was recorded for the first time from the East Al-Hammar marshes, South of Iraq. This species was collected from three stations during January and December 2021. The morphological features of the collected specimens were described for further taxonomic studies. In addition, somewaterquality parametersviz. temperature,PH,salinity, dissolvedoxygen, turbidity, conductivity, and total dissolved solids were measured of the sampling station during the study period are provided.

The population biology and stock assessment of African moony, Monodactylus sebaewas studied based on monthly length frequency data collected from New Calabar River, Nigeria fromFebruary 2020 to March 2021. The estimated von Bertalanffy growth parameters weregrowth performance index (2.91 per year), asymptotic length (L∞= 36.54 cm)and growth curvature (K = 0.61yr-1). The estimated theoretical age at birth (t0) and longevity for the assessed fish species were 0.55 years and 2.91 years, respectively. The total mortality (Z), natural mortality (M), and fishing mortality (F), were 1.87 year-1, 1.23 year-1and 0.64 0.64 year-1, respectively. The length at first capture (Lc) was 8.56 cm. The exploitation rate (E) and maximum exploitation rate (Emax) were calculated as 0.34 and 0.36, respectively. The recruitment pattern occurs throughout the year, with only one major peak in May with 19.9% recruits. Emaxwas 0.36, while E50was 0.23 indicating that the current exploitation rate was below the maximum sustainable yield, showing that this stock was underexploited.

The larvae of common carp (Cyprinus carpioL.) were studied for 6 weeks in an indoor recirculatory system (RAS) and an outdoor earthen pond to compare their effects on growth performance and survival rate. Larvae reared in outdoor earthen ponds achieved significantly higher total length, weight, weight gain, and length increments than indoor groups (P≤0.05). However, the indoor recirculatory system had the highest survival rate (83±1.9%) than outdoor earthen ponds (42±3.6%) (P≤0.05). The results of the present study revealed that the raising systemhas a significant impact on the survival and growth performance of the larvae in common carp, and the best growth performance was in the outdoor earthen ponds, while the better survival rate was recorded in the indoor recirculatory system. Therefore, to minimize mortality and maximize survival rate, it is suggested that the larvae were released after hatching into closed and controlled rearing systems before being reared into earthen ponds after starting the exogenous feeding.

Numerous studies have shown that herbs can be used as growth stimulants in aquaculture. This study aimed to investigate the effect of combined consumption of mint powder and vitamin D on the growth and health of juvenile rainbow trout, Oncorhynchus mykiss.For this purpose, a total of 200 juvenile rainbow troutwere divided into four groups and treated for 60 days as follows: The 1stgroup (control) used a standard diet; the 2ndgroup had 1.5% mint powder in their diet; The 3rdgroup having an additional amount of 120 mg/kg of vitamin D in their diet; The 4thgroup fed a diet having mint and vitamin D supplements as 2ed and 3rdgroups. All groups' growth and health indices viz. condition factor, hepatic steatosis index, visceral sensitivity index, spleen somatic index, weight gain percentage, specific growth rate, feed conversion ratio, satiety index, food conversion efficiency, and protein efficiency ratio were measured and compared on days 20, 40, and 60. The results revealed that the use of mint powder in the juvenile rainbow trout diet not only had no remarkable effect on the growth and health of fish but also improved their growth. In addition, all the analyzed indications of the mint powder group outperformed than the vitamin D group.

Sediment samples from six different locations of Buriganga River following exposure to Zebrafish (Danio rerio)eggs and larvae displayed prominent effects on both whole sediments and sediment organic extracts. The acute and sublethal effects during 96 h exposure period included (i) a significant (P<0.05) increase in morality and abnormalities in zebrafish eggs and embryos; (ii) a significant (P<0.05) reduction in hatching success and heart rate; (iii) increased frequency of helical tail and lordosis after96 h exposure to sediment extracts; (iv) developmental delay and yolk sac edema after exposed to whole sediments at 96h exposure period. Chemical analysis showed the increased concentrations of heavy metals (Zn, Cr, Cu, Pb, and Cd) in downstream (S1, S2, and S3) compared to upstream (S4, S5, and S6), where some ions such as Cd and Cr exceeded the Environmental Protection Agency’s Threshold Effect Level (EPA TEL). The current study delineates the contamination of extremely toxic compounds in the sediment ofBuriganga River, which may initiate toxic effects on the early life stages of fish. Therefore, integrating zebrafish embryo toxicity tests may be crucial for evaluating the sediment quality of polluted rivers.

This study evaluated the growth performance and feed utilization of Oreochromis shiranus and Coptodon rendalli fed on diets combining Moringa oleiferaleaf and Cajanus cajan. A factorial experiment (4×2) in a Completely Randomized Design with three replicates was used. Oreochromis shiranusand C. rendalli(22.20±2.03 g) were randomly selected, assigned to 24 experimental units and reared for 90 days. The fish were fed 32% protein diets formulated as follows: Diet 1-Control (0 g/kg M. oleifera leaf and 0 g/kg C. cajan), Diet 2 (100 g/kg M. oleiferaleaf + 150 g/kg C. cajan), Diet 3 -(200 g/kg M. oleiferaleaf + 300 g/kg C. cajan), and Diet 4 (300 g/kg M.oleiferaleaf + 450g/kg C. cajan). The results revealed that there were significant differences in final body weight, body weight gain, and specific growth rate among dietary treatments for both species (P<0.05). Coptodon rendalliperformed better in final body weight, weight gain, and specific growth (60.94±0.54 g, 39.47±0.53 g and 1.13±0.02 %/d, respectively) than O. shiranus when fed Diet 2. However, no significant difference was recorded in condition factor (CF) among the dietary treatments for both species (P>0.05). Coptodon rendalliobtained the best apparent feed conversion ratio (2.75±0.06) and protein efficiency ratio (0.73±0.02) than O shiranus,when fed Diet 2. It is therefore concluded that Diet 2 (100g/kg M. oleiferaleaf + 150g/kg C. cajan) recorded the best growth performance and feed utilization for both species and can replace soybean meal as a fish feed ingredient.

This work was conducted to study the biochemical characteristics of the bacterial species isolated from the beach soil, and water of Sawa Lake using molecular and morphological markers. Samples were collected from the water, and surrounding beach area. The results showed the presence of isolates, including Proteus mirabilis, Providencia vermicola, Alcaligenes aquatilis, Raoultella planticola, Enterobacter cloacae, Klebsiella pneumonia, and P. rettgeri. The molecular diagnosis confirmed those of Biochemical traditional markers using 16S gene primers.