Pakistan Journal of Marine Sciences

MODELLING CURRENT AND FUTURE DISTRIBUTION OF THE INVASIVE SILVER-CHEEKED TOADFISH LAGOCEPHALUS SCELERATUS IN THE MEDITERRANEAN SEA

Cemal Turan, Servet Ahmet Doğdu — Sat, 31 Dec 2022 00:00:00 +0000

The progress in species distribution modeling has brought new insights
into biological invasion management. The present study aims to model the potential
current geographic distribution and future expansion of silver-cheeked toadfish
Lagocephalus sceleratus in the Mediterranean Sea. Coordinates of 98 occurrence records
of L. sceleratus in the Mediterranean were used, and marine climatic variables were
collected from the global databases. Fifteen modeling techniques were tested, and
weighted ensemble averaging of the model replicates was built. AUC values for each
model ranged from 0.61 for rpart to 0.99 for rf, and TSS values varied from 0.41 for mlp
to 0.95 for rf. Based on the cutoff values of TSS and AUC, the seven modelling
algorithms were used for ensemble modeling. The maximum seawater temperature at
minimum depth explained strong biological importance to the current adaptation, and the
salinity contributed the most to the future adaptation. The ensemble forecasting of
suitable habitats of L. sceleratus for current distribution modeling revealed that
L. sceleratus dominantly occurred in the middle and eastern parts of coastal areas of the
Mediterranean. The future distribution was extended to the western part of coastal areas
of the Mediterranean, classifying the high suitability of these areas for its future
distribution. The suitable bioclimatic envelope of L. sceleratus under the present study is
predicted to widen because of climate change. The likely regions of invasion and the
areas at risk for a potential future invasion of L. sceleratus indicate that prompt, effective
practical actions by resource managers should be undertaken to mitigate its impacts and
spread.

EFFECT OF FREEZING PERIOD ON CHEMICALCOMPOSITION, MICROBIAL LOAD AND SOME PATHOGENICBACTERIA OF NILE TILAPIA (OREOCHROMIS NILOTICUS)

Hassan M. Yagoub — Sat, 31 Dec 2022 00:00:00 +0000

This study evaluated the effects of freezing periods on nutritional values,

microbial loads, and some pathogenic bacteria in Nile Tilapia (Oreochromis niloticus). 8

kg. Samples were collected from El-mawourda Fish Market in Khartoum State, for four

experimental treatments. The treatments were conducted on the period 0 day, 7 days, 15

days and 21 days. It is noticed that the freezing period effect on the nutritional value,

microbial load and some pathogenic bacteria of Nile tilapia (Oreochromis niloticus)

revealed that the lowest average nutritional assessment of Nile tilapia (Oreochromis

niloticus) observed for protein 20% at the third period of freezing (21 days), and minerals

were calcium, phosphorus, magnesium, iron, sodium and potassium (5.6 – 2.7%, 4.8 –

2.9%, 2.6 – 2.9%, 1.1 – 0.71%, 4.5 – 2.8%) respectively. The result of this study clarified

that the freezing period has a considerable consequence (p ≤ 0.05) on the chemical

composition, microbial load and same pathogenic bacteria (E. coli and Salmonella) of

Nile tilapia (Oreochromis niloticus).

A NEW SPECIES OF PHILOMETRA REPORTED FROM THE OVARIES OF EDIBLE FISH EPINEPHELUS BLEEKERI (VAILLANT 1878) OF THE KARACHI COAST

A.G. Rizwana, Sumbul Zulfiqar — Sat, 31 Dec 2022 00:00:00 +0000

Nutritionally, fish meat is identified as healthiest meat all over the world.
Nutriments that are essential for healthy diet can be easily drive from fishes. Beside fish
meat there are various type of derivatives that we can obtain from them. Economically
fish industry is considered as backbone for any country. Approximately, 45,000 species
of helminth parasites cause pathogenicity in vertebrate hosts that are known to man.
Parasite that belong to family Philometridae usually invade different body organs and
cavities of various fishes. Parasite that cause pathogenicity in reproductive organs of fish
ultimately cause disturbance in their release of reproductive hormones, mating behavior,
difficulty in spawning and ultimately number of fry production is declined.
This research was conducted on the nematode parasites of marine fish Epinephelus
bleekeri (Vaillant 1878) from Karachi coast during January,2021 to December,2021. In
this one year research, a new species of nematode Philometra bleekerii n.sp. was
recorded from the reproductive organs of marine fish Epinephelus bleekeri (Vaillant
1878).

ESTIMATION OF POPULATION STRUCTURE, GROWTH AND CONDITION OF LATES CALCARIFER (BLOCH, 1790) IN THE BAY OF BENGAL

Sat, 31 Dec 2022 00:00:00 +0000

The current study illustrates the life-history traits; including length
frequency distribution (LFD), length-weight and length-length relationship (LWR and
LLR), condition factors (allometric, KA; Fulton’s, KF; relative condition, KR; relative
weight, WR), and natural mortality (Mw) of Lates calcarifer from the Bay of Bengal,
Bangladesh. A total of 103 individuals were randomly collected from January to
December 2021 using traditional fishing gear including Koral net and gill net. For each
individual, total length (TL), standard length (SL), and total body weight (BW) were
measured with measuring scale to 0.1 cm and digital balance to 0.1 g precision,
respectively. The TL size class 84.0 cm was a numerically dominant group in the
population. The b value of LWR (TL vs. BW) indicated positive allometric growth
(b=3.28) pattern in the Bay of Bengal. Likewise, the b value of LLR indicated also the
same growth pattern. Among the four types of condition factors, KF is the best-suited tool
for evaluating the well-being of L. calcarifer. Additionally, WR exhibited significant
divergence from 100 (P< 0.0001), defining an imbalanced habitat. The calculated Mw was
0.23 year-1 for L. calcarifer. Therefore, these findings would be used in the future for the
improved management of this species in the Bay of Bengal as well as for connecting
ecosystems.

MORPHOMETRIC RELATIONSHIP OF PERNA VIRIDIS LINNAEUS, (1758) FROM THE MANORA CHANNEL, COASTAL WATERS OF PAKISTAN

Sat, 31 Dec 2022 00:00:00 +0000

Perna viridis (Green Mussels) is characterized by fast-growing, found in
large clusters, one of the dominant bio-fouling organisms, native to West Indo Pacific
region and commonly distributed along the Southeast Indian and Asian coast. They are
found in the shallow sublittoral water up to a depth of 15 m and be able to tolerate an
extensive range of environmental situation i.e. tolerate temperatures range of 15-32.5C.
Green mussels were collected from the navigation buoy in Manora Channel and brought
to the research laboratory. Samples were washed to remove the sand, vegetation, and
other particles. Morphometric measurements were measured to the nearest gram. The
result revealed that the shell length ranged between 0.60-7.4 cm, the width range between
0.10-2.9 cm, and the weight range between 0.037-15.549 g. In all morphometric
relationships, the validation of the “b” values was significantly different from the
isometric value. Significant correlation variation was observed in all variables whereas
the highest correlation values were observed in the length-width (n-224, r2 = 0.966) and
the lowest was observed in width-total weight (n-224, r2 = 0.85). The analysis of variance
(ANOVA) revealed that all variables showed significantly different (DF=1, p<0.000).

STUDIES ON THE MORPHO TAXONOMIC VARIATIONS OF FOUR CENTROPAGIDAE SPECIES (CRUSTACEA: ‎CALANOIDA) WITH NOTE ON THEIR ABUNDANCE ‎COLLECTED FROM SONMIANI BAY, NORTHERN ARABIAN SEA

Shumaila Mubarak, Qadeer Mohammad Ali — Sat, 31 Dec 2022 00:00:00 +0000

Centropagidae is comparatively a larger family to other families of order calanoida. The quantitative data revealed that the copepods of the genus Centropages are the dominant component in the zooplankton samples from the designated station in Sonmiani bay, a coastal lagoon at Balochistan coast, northern Arabian sea. Four epipelagic species of family Centropagidae, Centropages (Centropages dorsispinatus Thompson I.C. & Scott A., 1903, Centropages tenuiremis Thompson I.C. & Scott A., 1903, Centropages furcatus (Dana, 1849) and Centropages orsinii Giesbrecht, 1889 ) were identified. Male and female specimens were distinguished on their characteristic features of antennules, thoracic segments and fifth legs. Identified specimens were described briefly with their microscopic illustrations. Centropages dorsispinatus and Centropages tenuiremis were frequently found in zooplankton samples throughout the sampling season.