Mudskipper Research Articles

Detection of Polynuclear aromatic hydrocarbons in mud skippers (<i>Gobiformes oxudecidae</i>) from Jones Creek, Delta State, Southern Nigeria

The measurement of polynuclear aromatic hydrocarbons (PAHs) was conducted with respect to Gobiformes oxudecidae (mudskipper) specimens collected from Jones creek, Delta State. They were analyzed for 16 priority PAHs spanning through a total duration of eighteen months which adequately captured both wet and dry seasons. The ΣPAHs varied from 0.000 to 0.106 mg/kg for mud skipper samples within the aforesaid duration of the research. The most dominant PAH observed were chrysene and benzo(a)anthracene with amounts of 0.106 ± 0.095 mg/kg and 0.042 ± 0.030 mg/kg. The most abundant PAH in terms of its detection is chrysene accounting for 20.63% of the 16 PAHs while the least was dibenzo(a,h) anthracene with relative abundance of 0.37%. The individual component ratio revealed that refining operations, domestic and industrial discharges and possible storm run-off could likely be the source of contamination. The total amounts of PAHs in the rainy season were comparatively higher than values obtained in the dry season. Distribution patterns revealed that PAHs possessing 3 and 4 rings were dominant which confirmed the pyrogenic source of the detected PAH. The dominance of the low molecular weight PAHs across the sampling stations was indicative of their bioavailability for uptake by biota. Diagnostic ratio among others employed included phenanthrene/anthracene and benzo(a)anthracene/chrysene. Calculation based on these ratios to determine the PAHs emission origins suggested pyrolytic origin of the sediment associated PAHs coupled with a pyrolytic or pyrogenic source of PAHs present in the mudskipper specimens.

Rice farmers’ perception on occupational risk exposure to pesticides in Bangladesh

Rice is a staple food and pesticides have become a dominant input for production of rice in Bangladesh. To protect the farmers’ health and environment, farmers’ understanding about risk on occupational risk exposure to pesticides is a crucial matter. Accordingly, a study was carried out in Khagdohor union of Mymensingh Sadar upazila (sub-district) under Mymensingh district in Bangladesh to assess the rice farmers’ perception on occupational risk exposure to pesticides. An interview schedule was used to collect data during MarchApril, 2018 from 100 rice farmers. Data were analyzed using descriptive statistics, rank order and coefficient of correlation. Majority of the rice farmers (73%) had medium to high level of perception on occupational risk exposure to pesticides in the study area. Among twenty (20) statements on four (4) dimensions: ‘eating, drinking or smoking could be done during mixing and loading’; ‘after applying pesticides more time should be taken to change clothes or to take bath’; ‘pesticide store house can be also used for storing food, fire wood, farming equipment and kitchen utensils’; and ‘pesticides do not kill target or non-target organisms (snakes, worms, insects, mud skippers etc.)’ were the first ranked perceived risks by the rice farmers on occupational risk exposure to pesticides regarding handling; application; storage and disposal; and human health and biodiversity stages, respectively. It was revealed that the influential factors such as education, household size, farm size, annual income, organizational participation, training received, extension media contact, ownership of pesticide applicators, and perception on the use of pesticides of the rice farmers were significantly associated with the rice farmers’ perception on occupational risk exposure to pesticides. The study specified some recommendations for the policymakers to address the aforesaid influential factors of the rice farmers on occupational risk exposure to pesticides in the study area. Moreover, awareness raising programmes, credit facilities, proper training on safety measures and suitable extension services could play a significant role in lessening the risks of the rice farmers on occupational exposure to pesticides.

Effects of partial replacement of fishmeal protein by protein extracted from green seaweed (Cladophoraceae) in mudskipper (Pseudapocryptes elongatus) diets

The study was conducted to assess the possible utilization of protein extracted from green seaweed (Cladophoraceae) in mudskipper (Pseudapocryptes elongatus) diets. The fishmeal (FM) protein was replaced by protein extracted from green seaweed (EGW) at graded levels of 15, 30, 45 and 60%. The diet without green seaweed protein considered as a control treatment. All experimental feeds were formulated to be equivalent in crude protein (30%) and lipid (7%). Fish with average initial weight of 0.43 g were reared in the 100-L tank at a density of 30 fish per tank and salinity of 10 ppt, fed ad libitum twice a day. After 45 days of feeding trial, survival of experimental fish was not affected by the feeding treatments, varied in the ranges of 91.1- 94.4%. When fishmeal protein was replaced from 15% to 45% of protein extracted in the diets, growth rate of fish were better or similar to those in the control diet. Although feed conversion ratio (FCR) increased and protein efficiency ratio decreased with increasing levels of FM substitution from 30% upwards, statistical differences were not observed among feeding treatments. The proximate composition of fish fillet such as the moisture, lipid, and ash contents tended to decrease with increasing level of EGW protein while the protein contents slightly increased at higher inclusion of EGW protein in the diet from 15% to 45%. The present study indicated that protein extracted from green seaweed (Cladophoraceae) could replace fishmeal protein up to level of 45% in formulated feed for the mud skipper (P. elongatus) diets.

Diversity and distribution of fauna of the Nasese Shore, Suva, Fiji Islands with reference to existing threats to the biota

Faunal diversity and distribution in the Nasese Shore, Suva, Fiji Islands were studied April–August 2014. The belt transect method was employed to study the species richness and abundance of the fauna. Opportunistic observations were performed to supplement the species richness of the selected habitat types: sandy, rocky and muddy (SRM; Habitat 1); mangrove and sandy (MNS; Habitat 2); muddy and sandy (MS; Habitat 3); and rocky and coral (RC; Habitat 4). Sampling was performed during high and low tide. Faunal density was highest in the RC substrate. The density of mud skippers was significantly higher in the MNS habitat than in the other habitats. This findings could well indicate the environmental pollution levels of this habitat. The Shanon–Weiner Index indicated that the RC habitat possesses the highest diversity, whereas the MS habitat possesses the lowest diversity. In addition, major threats to the biota existed.

A human health risk assessment of mercury species in soil and food around compact fluorescent lamp factories in Zhejiang Province, PR China

This study investigated total mercury (THg) and methylmercury (MeHg) contamination in a major production center of compact fluorescent lamps (CFLs) located in Gaohong, Zhejiang Province, China. This was a result of the growing concern associated with the release of mercury into the environment from such components. The results of the study included the following mean concentrations for THg and MeHg of 157±11 (61–518)ng/gdw and 0.28±0.07 (0.07–0.67)ng/gdw in agricultural soil, respectively, and 18.6±6.5 (3.2–47.8)ng/gww and 0.11±0.03 (0.02–0.37)ng/gww in vegetable samples, respectively. A significant correlation was observed between THg in vegetables and corresponding soil samples (r=0.64, p<0.01). THg and MeHg in sediment samples had respective concentrations ranging from 28 to 1019ng/gdw and 0.11 to 3.15ng/gdw. Mud skipper bought from the local market contained the highest Hg (THg: 170±45ng/gww, MeHg: 143±37ng/gww) amongst all fish species (THg: 14–170; MeHg: 11–143ng/gww) of the study. The risk assessment indicated that fish consumption should not result in a MeHg EDI exceeding the RfD (0.1μg/kgbw/d) for both adults and children, when MeHg bioaccessibility is taken into account.

A comparative study on the responses of the gills of two mudskippers to hypoxia and anoxia

A comparison of branchial enzyme profiles indicates that the gills of Periophthalmodon schlosseri would have a greater capacity for energy metabolism through glycolysis than those of Boleophthalmus boddaerti. Indeed, after exposure to hypoxia, or anoxia, there were significant increases in the lactate content in the gills of P. schlosseri. In addition, exposure to hypoxia or anoxia significantly lowered the glycogen level in the gills of this mudskipper. It can be deduced from these results that the glycolytic flux was increased to compensate for the decrease in ATP production through anaerobic glycolysis. Different from P. schlosseri, although there was an increase in lactate production in the gills of B. boddaerti exposed to hypoxia, there was no significant change in the branchial glycogen content, indicating that a reversed Pasteur effect might have occurred under such conditions. In contrast, anoxia induced an accumulation of lactate and a decrease in glycogen in the gills of B. boddaerti. Although lactate production in the gills of these mudskippers during hypoxia was inhibited by iodoacetate, the decreases in branchial glycogen contents could not account for the amounts of lactate formed. The branchial fructose-2,6-bisphosphate contents of these mudskippers exposed to hypoxia or anoxia decreased significantly, leaving phosphofructokinase and glycolytic rate responsive to cellular energy requirements under such conditions. The differences in response in the gills of B. boddaerti and P. schlosseri to hypoxia were possibly related to the distribution of phosphofructokinase between the free and bound states.

Induction of ovulation in female mud skipper (Boleophthalmus pectinirest ris) by HCG, analogue of LHRH and pimozide

The effects of two intraperitoneal injections of human chorionic gonadotropin (HCG) or [D-ALA6, pro9-N-ethylamide]-luteinizing hormone releasing hormone analogue (LHRH-A), respectively, and the combined effect of LHRH-A with pimozide (PIM), a dopamine antagonist, on ovulation in female mud skipper were investigated. A high rate of ovulation (83.3%) was observed after injection with HCG(30 I. U./g). Injection of LHRH-A at a total dosage of 2 μg/g was 100% effective in inducing ovulation. No ovulations occurred in the group receiving a low dosage of LHRH-A (0.02 μg/g). Injection of LHRH-A (0.2 μg/g) with PIM (10 or 20 μg/g) induced greater ovulatory response than injection with LHRH-A (0.2 μg/g) alone. PIM at total dosages of 0.2 μg/g or 2 μg/g did not enhance the potency of LHRH-A to stimulate ovulation.

Fatty acids of the mud skipper Boleophthalmus boddaerti.

AbstractThe fatty acid composition of the body and the liver lipids of Boleophthalmus boddaerti, a mud skipper fish belonging to the Gobiidae family, have been determined by argentation column chromatography (a.c.c.) and gas‐liquid chromatography (g.l.c.). The levels of 20:5ω3 (ca 14%), a biologically important fatty acid, was found to be considerably high. Other major component acids were, 16:0, 18:0, 16:1, 18:1, 20:3ω9, 22:5ω3 and 22:6ω3. Besides, a large number of minor components were identified and estimated. The liver lipid contained unusually high levels (ca 90%) of non‐saponifiables.

Water intake, gut absorption and sodium fluxes in amphibious and aquatic fishes

1. 1. With lowered external salinity, the drinking rates of the marine fish, Pelates quadrilineatus, decreased significantly from 9·57 ± 0·46 to 5·76 ± 0·87 μl/g per hr, whereas those of the almost terrestrial mud skipper, Periophthalmus vulgaris, increased from 3·55 ± 0·61 to 10·83 ± 2·15. Rates in three other species of marine or fresh-water fish were not related to external salinity. 2. 2. Gross 22Na effluxes of both Periophthalmus and Pelates were similar, and linearly related to external salinity. 3. 3. The adaptation of Periophthalmus appears to be behavioural rather than physiological. 4. 4. Pelates gut ions, at two different external salinites, were highly variable, and indicated that water absorption is probably regulated at the gut wall rather than by drinking rate. Calcium appears to be excreted into the gut. 5. 5. It is concluded that water drinking may also serve for elimination of substances, such as Ca, excreted into the gut.

5. On a Myxosporidian. Sphærosporn periophthalmi, sp. n., found in African and Indian Mudskippers (Pisces), and its possible significance.

5. On a Myxosporidian. <i>Sphærosporn periophthalmi</i>, sp. n., found in African and Indian Mudskippers (Pisces), and its possible significance.