In the present study, Scomberomorus commerson was collected during the period 2006-2011 in order to provide information on the concentrations of eight heavy metals present in this marine species commonly consumed by the population and to have knowledge whether these levels may constitute a hazard to consumers. Liver showed high concentrations of metals in the tissues and organs. Fe is the most accumulated in all tissues and organs. The highest mean concentration of Fe (608.93+113.22 µg/g), Mn (9.79+4.22 µg/g), Cu (38.57+16.62 µg/g), Zn (53.25+26.50 µg/g), Ni (3.22+1.13 µg/g), Pb (1.20+0.64 µg/g), Cd (2.03+0.91 µg/g) and Cr (1.93 + 0.87 µg/g) was determined in liver of fish. The order of abundance of the metals in the fish samples based on concentrations in the muscle tissues analysed were as follows: Fe>Zn>Cu>Mn>Ni>Cd>Pb≥Cr. For the toxic metal, Pb was found to have lower concentration of the mean values than the permissible limits set by FAO/WHO. However, Cd level was higher than the permissible limit and it can be concluded that the contamination of Cd in S. commerson may pose threat for the importers due to high per capita consumption of the fish.
The present study aimed to estimate the growth pattern through length-weight relationships (LWRs), condition (Fulton's condition factor, KF) and prey-predator status through relative weight (WR) of 9 fish species e.g., Netuma thalassina, Epinephelus coioides, Acanthopagrus berda, Acanthopagrus latus, Acanthopagrus bifasciatus, Parastromateus niger, Aluterus monoceros, Sphyraena putnamae, and Lates calcarifer belong 7 families from the Arabian Sea of Pakistan. Occasionally samples were collected from marine waters of the Arabian Sea connected to Baluchistan and Sindh province from June 2018 to May 2019 by bottom and midwater trawl nets, gill nets, and trammel nets. Individual whole body weight (BW) and total length (TL) were measured. The growth pattern either allometric (+/-) or isometric was calculated as LWR: BW = a × TLb. a and b were the LWR parameters. Condition factor was calculated as KF = (BW/TL3) ×100 and prey-predator status was as WR = (W/WS) × 100, where WS = a×TLb. This study recorded a new maximum TL (150.0 cm) for S. putnamae. The b values of LWR ranged from 2.02 to 2.76 with r2 ≥ 0.95 that indicated a negative allometric growth pattern. Additionally, the study estimated KF mostly above 1.0 except A. bifasciatus, A. monoceros, and S.putnamae. The prey-predator status was mostly balanced except for L. calcarifer. The findings of this study will be valuable for fishery managers to impose sustainable fishery management in the Arabian Sea (Baluchistan and Sindh), Pakistan, and adjacent ecosystems.
The present study was carried out to assess the reproduction weight-length based growth and condition factor of Holothuria arenicola Semper, 1868, from January to December 2018, in Karachi coast, Northern Arabian Sea. The sex percentage was determined as 33.3% females and 66.7% males. Length of specimens ranged from 14 and 38 cm and weight of specimens ranged from 21 and 82 g. The relationship was W = 2.408 L0.9482 (R2 = 0.999) for females, W = 0.989 L0.9482 (R2 = 0.998) for males and W = 1.234 L1.1565 (R2 = 0.999) for all individual. The condition factor ranged between 0.84 and 2.62 (mean: 1.52±0.70) in females and between 0.83 and 2.67 (mean: 1.43±0.71) in males. The gonadosomatic index of specimens ranged between 5.50 and 10.66 (mean: 7.95±1.24). The gutted weight of specimens ranged between 2.10 and 11.44 g (mean: 4.91±1.77). Studies about environmental variables and characteristics are necessary in order to complement the understanding of reproduction, the length-weight relationships and condition of sea cucumber in Karachi coast.
A preliminary study was conducted on the occurrence and abundance of zooplankton in the Karachi backwaters. Zooplankton sampling was conducted on monthly basis and the study was carried out on the basis of three seasons including pre-monsoon (January to May), monsoon (June to September) and post-monsoon (October to December) from a permanent station Napier Mole bridge (24o50’34’’.90 N, 66o59’17’’.55 E) during June 1996 to May 1998. The hydrographic parameters including air temperature (oC), water temperature (oC), salinity (ppt), dissolved oxygen (mg/L), pH, and transparency (cm) were recorded. Total 14 groups of zooplankton were recorded; hydromedusae, copepoda, mysids, amphipoda, acetes, lucifer, chaetognath, penaeid pl, caridean pl, zoea, megalopa, squilla larvae, fish larvae, fish eggs and others. Pre-monsoon season shows highest number of individuals and copepods were found to be the dominant group in all seasons. Zooplankton diversity, equitability and margalef index were measured seasonally. Highest shannon – wiener diversity index H' = (1.83), equitability E= (0.69) and margalef species richness Index d= (1.37) were measured in post-monsoon season. Statistical analysis (ANOVA) was performed in between seasons and zooplanktonic groups. No significant difference (at P>0.05, 0.148) was observed between zooplankton and seasons.
Microplastics are one of the major pollution problems nowadays, have been found in both marine environments and various fish species worldwide. In this study, the presence of microplastics in the digestive systems and the gills of 6 species from the Scombridae family on the coast of Karachi in Pakistan was investigated. A total of 336 fish were examined for the presence of microplastic in gills and the digestive systems. Microplastics were detected in digestive systems and gills in 11.11%-19.51% and 58.62%-85.71% of total individuals, respectively. The number of microplastics varied from 0.19 to 1.12 items.ind-1 in digestive system and 1.5 to 7.04 items.ind-1 in gill. Fibre was dominant in both gills (98.67-99.17%) and digestive systems (100%). More extensive and further investigations are needed on microplastic contamination of the biota on the Pakistan coast.
The present study was conducted in the coastal pond ecosystems of Pakistan to evaluate the optimum salinity level for the best growth performance of a commercial shrimp, Litopenaeus vannamei.Total of 6 lac seed was randomly distributed in three ponds with an average initial body weight of 0.1±0.01g.The shrimps were cultivated in three different ponds demarcated as pond 1, pond 2 and pond 3 with salinity levels of 8 ppt, 22 ppt and 42 ppt, respectively for 105 days.The pacific white shrimp were fed with 35.0%crude protein diet with feeding frequency of 4 and initially feeding rate of 10% biomass per day.The feeding rate adjusted according to shrimp biomass on a weekly basis.Final weight, specific growth rate, average daily weight gain, viscerosomatic index, hepatosomatic index and survival rates were found optimum at salinity level of 22 ppt compared with salinity levels of 8 ppt and 42 ppt (p <0.05).FCR was better at 22 ppt salinity compared with two other tested salinity levels (p <0.05).The 22 ppt salinity level resulted in optimum growth of L. vannamei which might be due to improved osmoregulation.Feeding frequency of 4, protein 35% and salinity of 22 ppt were found suitable factors for the growth performance of L. vannamei reared in aquaculture system.
Nowadays metal bioaccumulation in holothuroids is increasing and is a cause of worry owing to toxicity.In the present study the concentrations of mercury (Hg) were measured in holothuroids (Holothuria (Thymiosycia) arenicola Semper, 1868, Holothuria (Lessonothuria) pardalis Selenka, 1867, Holothuria (Lessonothuria) verrucosa Selenka, 1867 and Holothuria (Halodeima) atra Jaeger, 1833) collected during different seasons (pre-monsoon, monsoon, and post-monsoon) in 2015 at Buleji and Sunehri coasts of Karachi, Pakistan.Hg concentrations of tentacles were higher than those in muscle, tentacle and gut tissues of the pre-monsoon, monsoon and post-monsoon.The lowest Hg concentrations were found in muscle tissues at all seasons in Buleji and Sunehri coasts.The mean levels in the muscle tissues were 0.018 mg/kg dry wt.for H. arenicola, 0.024 mg/kg dry wt.for H. verrucosa, 0.026 mg/kg dry wt.for H. pardalis and 0.036 mg/kg dry wt.for H. Atra.The results indicate that according to the European Union legislation the Hg amounts in all tissues of holothurians is much lower than permitted levels.In terms of Estimated Weekly Intakes, this current work also proved that there was no likely health hazard to consumers on account of intake of sea cucumbers under the current consumption rate in Buleji and Sunehri coasts of Karachi, Arabian Sea.
To estimate the growth parameters, the non-seasonal von Bertalanffy and Hoenig seasonal von Bertalanffy models were fitted to the length frequency data of Holothuria pardalis and H. verucosa obtained from coastal areas of Karachi during January and December 2018. The Hoenig seasonal von Bertalanffy growth parameters were estimated as L∞ = 18.0 cm total length (TL), K = 1. 00 year-1 for H. pardalis and as L∞ = 18.0 cm TL, K = 0.86 year-1 for H. verrucosa. H. verrucosa individuals reached 68.9% of their maximum total length at the one year old class. For H. pardalis it was calculated as 54.2%. The seasonal oscillation in growth rate for H. pardalis (C = 0.90) was larger than it was for H. verrucosa (C = 0.18). The slowest period of growth corresponded to June in H. verrucosa and February in H. pardalis may be the result of the extended both reproduction and poor nutrition periods due to high rainfall regime. The relatively high growth rate (K) of these species may have important implications for their survival, mainly in environments where conditions cause biological stress and oceanic disturbances but may also increase its potential as a candidate for aquaculture.
'/%3e%3cpath fill='%23fff' d='m8.751-17.959 10.11 11.373L3.997-9.844l13.94-6.1-7.692 13.129z'/%3e%3c/svg%3e)
'/%3e%3cpath d='M200 752.362h200v300H200z' style='fill:%23fff;fill-opacity:1;stroke:none' transform='translate(0 -752.362)'/%3e%3cpath d='M400 752.362h200v300H400z' style='fill:%23ff883e;fill-opacity:1;stroke:none' transform='translate(0 -752.362)'/%3e%3c/svg%3e)
