International Journal of Aquatic Biology
Volume:6 Issue: 2, Apr 2018

The current study estimated the immunotoxicological effects of the herbicide chlorpyrifos at sub-lethal concentration and the potential ameliorative effects of galactooligosaccharide (GOS) in Danio rerio. Fish was sampled after a 56-days feeding with GOS and then exposed to 15 mg/l chlorpyrifos for 7-days to assess the non-specific immune responses (total protein, immunoglobulin and ALP activity). The results revealed that feeding zebrafish with 1% dietary GOS increased total protein levels (P0.05). There were significant difference between total immunoglobulin levels 1% and control group (P0.05). The present findings revealed that dietary supplementation with GOS could be useful for modulation of the immunity in response to chlorpyrifos exposure, thereby presenting a promising feed additive in aquaculture.

This study aimed to investigate the effects of sublethal concentrations of oxadiargyl herbicide on growth performance, serum biochemical parameters and liver histology of the common carp, Cyprinus carpio, during 30 days exposure period. Carp fingerlings were randomly divided into four duplicate groups. Experimental groups were exposed to the concentration of 0.1, 0.3 and 0.5 ppm of oxadiargyl, while the control group was kept in toxicant free. During the experiment, none of the control fish died. Weight gain and condition factor decreased, while food conversion ratio increased in fish exposed to 0.5 ppm of oxadiargyl. Exposure to oxadiargyl significantly increased serum ALT, AST and ALP, as well as glucose levels, while cholesterol, total protein and albumin were significantly decreased in the exposed fish groups depend on oxadiargyl concentrations and exposure time. Diffuse and focal necrosis mainly as perivascular necrosis fibrosis, increase in size and number of melanomacrophage centers, bile duct hyperplasia, hyperemia and hemorrhage, fatty changes in the hepatocytes, fibrocyte aggregation and focal inflammatory cells were also the histological le­sions observed in the liver of exposed fish. These results showed that oxadiargyl is highly toxic to common carp and had negative effects on the growth performance, serum biochemical parameters and the liver tissue of common carp.

The Neotropical hermit crabs’ behaviour is rarely studied, although it is an important tool for the conservation of these invertebrates. In this context, the present study aimed to describe the hermit crab ethogram on its behaviour in the choice and dispute by shells. 60 specimens of hermit crabs were collected that were occupying mollusc shells Cerithium atratum, in sandstone reefs. In the laboratory, 30 hermit crabs were removed from their host shells by heating, the rest remained in their shells. The specimens were submitted to five experimental tests: (I) behaviour, (II) shell dispute, (III) shell preference, (IV) specimen behaviour with and without shell, and (V) shell contention between individuals with and without shell. The ethogram was built and evaluated by the Ad Libitum type of observational sampling methods and by the scanning type, for 30 uninterrupted minutes, records every two minutes, in total 15 observations per each observer. There were eight behavioural acts divided into 4 categories: immobility, interaction between specimen, environment exploration, and shell occupation. The most frequent behaviour was "walking", for both hermit crabs (54.2%) and those without shell (59.3%), followed by the rest of the individuals with and without shell, 16.9% and 12.4%, respectively. All hermits preferred mollusc shell Bulla striata, when offered in conjunction with the shell of Astrea tecta. However, all specimens returned to C. atratum shells when it was experimentally offered with all shells. Studies with hermits have shown that the species has preferences of gastropods shell C. atratum.

The present study aimed to evaluate the length-weight and Length-length relationships as well as the condition factor and gonadosomatic index of the Blackspot snapper, Lutjanus fulviflamma in the northern Persian Gulf, Hormozgan Province, Iran. The specimens were collected monthly from April 2016 to March 2017. The size (TL, total length; FL, fork length; SL, standard length) were measured and weighted (BW, total body wet weight). A total of 446 individuals were analyzed. The TL-BW relationship indicated isometric growth pattern in both sexes. In females, the means for condition factor was higher than males. In both sexes, the lowest value of both condition factor and gonadosomatic index were detected in autumn with ascending trend in the next seasons reaching the peak in spring. The oscillation in condition factor, as well as gonadosomatic throughout the sampling year, was most prominent in females which may be related to the reproductive cycle. The information reinforces data to define fishing closed seasons in this important fish that is used in many places in the world.

Piabanha, Brycon gouldingi, is an endemic species in the Tocantins-Araguaia basin. It has aroused the interest of both fish farmers, who started its creation in confinement, and riverine people who appreciate it as a food source. In order to provide information about organic systems of B. gouldingi larvae, a histological description was performed after capturing adult specimens in the Rio das Mortes (Mato Grosso, Brazil), adapted to captivity and induced to spawn at Buriti Fisheries (Nova Mutum, MT, Brazil). The collection of samples took place at pre-defined moments after hatching, and the processes relating to morphological differentiation of digestive, excretory, cardiorespiratory, nervous/sensory systems and gas bladder were characterized. At the hatching were found: undifferentiated digestive system; pronephros (primitive kidney), rudimentary heart, central nervous system characterized by primary vesicles, optic vesicle forming the optic cup and crystalline lens. In the course of ontogeny, these organic systems were developed and at the time of the total absorption of the yolk at 55 hours post-hatching were found: the digestive system consisting of the head gut, foregut, midgut and hindgut; two heart chambers and branching of gill arches; three regions of the brain (forebrain, midbrain and hindbrain), neuromasts, olfactory cavity, taste buds; eye consisting of well-defined layers; presence of gas bladder. The results of this study may be useful in providing support for the captive breeding of B. gouldingi during the larval stage.

Rotifers are important zooplankton in commercial finfish hatcheries. However, due to the limited variety of food available, zinc content of cultured rotifers in artificial environments may not meet the requirements of fish larval. It has been reported that direct addition of soluble zinc to culture media was not effective on the zinc content of rotifer. Thus, in this study, the effect of zinc-enriched Saccharomyces cerevisiae was investigated on the growth and mineral composition of rotifer, Brachionus plicatilis. Four different food treatments, including (1) yeast without enrichment (control), (2) yeast containing 21.23 mg g-1 of zinc, (3) yeast containing 56.25 mg g-1 of zinc, and (4) yeast containing 132.93 mg g-1 of zinc, were used to produce rotifer for a period of 10 days. Afterwards, specific growth rate (SGR), the total number of rotifers, total eggs attached to rotifers, and the total number of eggs were measured. Finally, the mineral composition of rotifer in different treatments was analyzed. The findings revealed that yeast enriched with 56.25 mg g-1 of zinc significantly improved the growth of rotifers. The maximum number of rotifers (274 ind ml-1), total eggs attached to rotifers (29.3 number ml-1), and the total number of eggs (36 number ml-1) were found in the third treatment. The highest zinc content was observed in the fourth treatment (about 822.5 μg g-1 of rotifers). The maximum values of Fe (13.84 μg g-1 of rotifers) and Mn (15.22 μg g-1 of rotifer) were related to the treatment 4 and control, respectively. However, the amount of Cu did not significantly differ among the treatments. In conclusion, this study found that zinc-enriched yeast improved the growth, reproduction, and body composition of B. plicatilis.

The spectrum size has been used to assess environmental disturbances and to understanding the energy flow in ecosystems. The objective of this work was to investigate if the operation regimes of reservoirs, including run-of-river and storage systems, interfere with the biomass spectra of fish fauna. We tested the hypothesis that the run of river reservoirs present higher proportions of large individuals than storage system. Samplings of fish fauna were carried out between January 2005 and December 2007 at six Neotropical reservoirs belonging to the sub-basin Iguaçu River and Coastal basin in São Jorge River, Brazil. The spectrum calculation was performed using the Pareto type I continuous distribution model. Reservoirs operated under run-of-river regime had significantly higher values than those operated under storage regimes. This study has elucidated some impacts of reservoir operating regime on biomass spectra and indicated differences in size spectra of fish assemblages among the sampled reservoirs. Therefore, it is important to incorporate management plans that take dam operating mode into account so that conservation of aquatic fauna, especially fish, is more effective.

The main objective of this study was to investigate whether dietary cereal grains of different carbohydrate sources can change nutrient digestibility, evacuation rate and the number of bacterial colony in gut. Common carp with an average weight of 244.7±6.3 g were divided randomly into sixteen 500-L tanks with a stocking density of 18 fish per tank. Four experimental diets were formulated by inclusion of four cereal grains (wheat meal, barley meal, corn meal and rice meal) in a basal diet in a ratio of 40%. The four experimental treatments with four replicates were assigned in 16 tanks. Inclusion of different types of cereal grain affected growth related parameters in C. carpio. Corn and wheat diets led to larger weight gains and better feed conversion ratios compared to barley diet (324 and 321 versus 305 g for final weight; 1.93 and 1.90 versus 2.25 for fed conversion ratio). Protein and dry matter digestibility in the common carp fed rice diet were lower in comparison to other cereal grains (73 and 58 versus 79-82 and 67-70%). The maximum and minimum bacterial colony numbers (133 and 63 cfu.gr-1×10-7) were observed in fish fed wheat and corn diets, respectively. Evacuation time showed a delay by feeding on barley diet and almost all dry matter left in part I of the intestine after 30 min (first sampling), but this rate was recorded 70% for corn diet .In conclusion, although dietary grains change evacuation time and bacterial colonial number in common carp, this condition does not have a great impact on nutrient digestibility.