Karachi Coast Research Articles

Preliminary assessment of microplastic in rhizosphere and non-rhizosphere region of mangrove at four locations along Karachi coast, Pakistan

Mangrove ecosystem faces significant threats from the various pollutants including microplastic (MPs). The aim of this study was to assess variations in MP distribution in mangrove sediments of rhizosphere (R) and non-rhizosphere (NR) regions. A total of 14,960 MP particles were identified from Sandspit backwater (SS-1 & SS-2) and Creek areas (PQ & KC). Notably, the NR showed higher MP counts (7848) compared to the R region (7112). Analysis revealed variations in MP types, with beads being predominant in both R and NR, followed by film, fiber, and fragments. KC exhibited highest MP contamination, followed by PQ, SS-2, and SS-1. Fourier-transform infrared (FTIR) analysis confirmed the presence of polyethylene terephthalate and polyethylene in sediments samples. This first detailed report on MP in mangrove sediments and other limited studies from Pakistan establishes the widespread distribution of MPs in the coastal area and provide a baseline for further elaboration in future.

Sediment Characterization and Monsoonal Impact on Beach Morphology at the Three Beaches along the Karachi Coast, Pakistan

Sediment characteristics plays important role in the determination and functioning of coastal ecosystems.The present study is an attempt to evaluate the variability in sediment characteristics of the three beaches: Clifton,Sandspit and Buleji, at the Karachi coast. The samples were collected during pre-monsoon and south-west monsoonseasons to evaluate the seasonal differences. The sediments of the three sites showed variations in moisture content,organic matter and grain size. The highest mean moisture (27.17%) and organic contents (3.5 %) were recorded fromthe sediments of Clifton. The maximum fraction of sediments (> 80 %) consist of fine to very fine sand at all studiedsites. The sediments of Clifton were high in very fine sand fraction and low in coarse sand fraction as compared toSandspit and Buleji. The sediments of all the three studied sites are moderately sorted, negatively coarse-skewed andshowed leptokurtic distribution. The studied beaches of Clifton, Sandspit and Buleji shows dissimilarity in sedimentcharacteristics as indicated through Cluster and PCA analysis. The monsoonal influence on sediment characteristicswas also observed at all the three studied beaches. The strong wave action during SW monsoon season results in thedeposition of the coarser sediments at the high tide level thus increasing the steepness of the beaches.

Occurrence of new Philometra sp. in mangrove red snapper Lutjanus argentimaculatus from the Karachi coast, Pakistan.

A recent examination of Philometra nematodes from mangrove red snapper Lutjanus argentimaculatus (Forsskal, 1775) from the Karachi coast, Kemari was done in the years 2021-2022. The present study reported three new species of genus Philometra (Costa, 1845) (Nematoda: Philometridae) Philometra kolachii, Philometra lutjani and Philometra kemarii. A total of 140 fish samples were examined, and 76 were infected. The intensity of infected fish was 54.28%. In Pakistan, literature on Philometrid nematodes is limited, therefore, this research would be helpful for the documentation and enhancement of nematods in Pakistan.

Study of some morphometric and meristic characteristics of Alepes vari (Cuvier, 1833) collected from the Arabian coast.

The present study examines the correlations between fifteen morphometric and ten meristic characters and total length (TL) of males, females, and combined sexes of Alepes vari (Cuvier, 1833) collected from Karachi fish harbor, West Wharf of Karachi Coast. Statistical analyses of linear regression relationships show mostly strong correlations (r≥0.70; p<0.05) between total length (TL) and most morphometric characters in males, females, and combined sexes, except the height of pectoral-fin (PFH), and pelvic-fin base length (PelFL); whereas, meristic characters were found to be constant and indicate weak or negative type correlations (r≤0.50; p>0.05) with total length (TL). Hence, according to our present results, there is a direct relationship between the total length of fish and all morphometric characters, which were found to be the best indicators of positive allometric pattern growth in fish. Moreover, analysis of the 2-sample t-test revealed (t-test; p>0.05) that no sexual dimorphism was reported in Alepes vari. Thus, our present study could be valuable in systematic classification, sexual dimorphism, and management of this species on the Karachi coast.

Studies on the Prevalence Rate of Neoplastic Growth in Fish Johniuss Dussumieri (Valenciennes, 1833) of Karachi Coast Due to Polluted Sea Environment

Background: With the growing concern over the impacts of environmental pollution on marine life, this study addresses the critical issue of neoplastic growth in fish populations. The increasing prevalence of tumors in fish due to contaminated marine environments has raised alarms about ecosystem health and public health implications. Objective: The primary objective of this research was to assess the prevalence and seasonal variation of neoplastic growth in fish populations, particularly focusing on the impact of environmental pollution. Methods: Fish specimens were collected from various markets and examined for neoplastic growth. The study employed observational techniques, statistical analyses including ANOVA and Duncan's Multiple Range Test, and assessed seasonal variations from January 2019 to December 2022. Results: A total of 2,373 fish were examined, with 193 cases of neoplastic growth identified, indicating a substantial prevalence of tumors. The statistical analysis revealed significant variations in tumor prevalence, with a notable correlation to environmental factors. Conclusion: The study concludes that environmental pollution significantly impacts the prevalence of neoplastic growth in fish populations. This has profound implications for marine ecology and public health, emphasizing the need for effective environmental management and pollution control measures.

Comparison of salinity tolerance between Avicenna marina and Rhizophora mucronata Karachi coast, Pakistan

Mangrove propagule size variation is an important factor in their survival. The main aim of this study was to determine the productivity and identify the comparison between Avicenna marina and Rhizophora mucronata. However, it is less studied about the comparison of mangrove species and their salt tolerance in terms of seedling establishment of propagules. We investigated the propagules size variation of Avicennia marina and Rhizophora mucronata from the Indus delta and were grown in the polythene bags of 5x10″ filled with silty soil from field nursery. We used salinity and nutrients treatments to propagules to identify the growth rate of mangrove species. The surveying technique was also used to collect the information of mangrove forest from local communities. We detected that Rhizophora mucronata had a higher productivity rate due to the given concentration of 50% sea water. While the Avicennia marina showed a lower decline ratios growth at 25% salinity level with further increases in salinity. Using diffusion porometers and infrared gas analyzers (IRGAs), we revealed that stomatal conductance was higher in Rhizophora mucronata, followed by Avicennia marina. Moreover, our outcomes showed a higher Sodium and chloride ions with the increase in salinity and also demonstrated a higher accumulation in Avicennia marina. Overall, its was found that Avicennia marina is the most salt resistant species and it’s a dominated species in littoral forest. Our outcomes can help us to better understand the green infrastructure design of mangroves, suggesting that selecting multiple techniques ensure many post-tsunami restoration initiatives are encountering problems.

Spectral indices for enhancing aquatic vegetation: a case study of seaweed on the Arabian coast of Pakistan using Worldview-2 data

ABSTRACT This study assessed the performance of widely used aquatic vegetation indices and introduced a novel index – the normalized difference aquatic vegetation enhancing index (NDAVEI). The NDAVEI was used to map seaweed resources in Pakistan along the 1,050 km long Karachi coast, and the results were compared with those obtained from other vegetation indices. Due to their widespread use in food, cosmetics and industrial goods, seaweed resources have great economic potential. They also play a significant role in aquaculture and fish breeding. Many sea species rely on seaweeds for their shelter and food requirements. The conservation of marine biodiversity needs seaweeds’ systematic monitoring and mapping to maintain the dependent species’ vital biological associations. Despite rich seaweed stock, these resources remain largely unmapped in Pakistan. Given these precious coastal resources’ significant economic and ecological importance, there is a pressing need to preserve and map seaweed sites in Pakistan. Traditionally, marine scientists have used sampling methods to describe shallow intertidal water marine habitats, but these methods are time intensive. Remote sensing (RS) data and geographical information system (GIS) tools are efficient and less time-consuming for mapping and classifying marine resources. This study compared the effectiveness of commonly used indices and NDAVEI to extract and map seaweed resources using high-resolution WorldView-2 satellite data. The results were verified through site observations. The NDAVEI can potentially improve the effectiveness and efficiency of seaweed mapping efforts. When combined with object-based image analysis (OBIA), it provides more precise area estimation than other indices.

Microplastic contamination from surface waters and commercially valuable fishes of Karachi Coast, Pakistan

Microplastic (MPs) pollution is a major concern due to extensive human plastic dependency that is deteriorating ecological health of the world’s oceans. This study was conducted to observe MPs contamination in surface water samples and gastrointestinal tracts of 127 fishes attributed to 15 species from Karachi coast, the busiest port of Pakistan. Total of 6319 MPs/m3 were recorded during this study from water samples where 73% MPs recorded from Manora channel (Karachi harbor) and 27% from open ocean. The most dominant MPs were fibers (42%), pellets (27%), and fragments (20%) respectively. MPs abundance differed significantly among species and ranged between 20.833 ± 2.522–76.400 ± 7.869 item ind.−1. Fibers were the most dominant type in all samples (53.39–90.0 %) followed by pellets (4.88–20.22 %) and blue (21.60–66.23 %) was the most common color. The mean size of MPs ranged between 0.34 mm (Otolithus ruber) to 2.1 mm (Terapon jarbua). The mean highest number of MPs were recorded from shallow coastal fishes (440 item ind.−1) followed by estuarine and shallow coastal fishes (385 item ind.−1). MPs abundance differed significantly among species from different habitat type (Kruskal–Wallis Test, P < 0.0001) with negative correlation between MPs abundance in GITs of fishes and their habitat (Spearman’s rho, r = -0.143) whereas MPs abundance was not significantly correlated with body weight (F = 0.002, p = 0.963), suggesting that MPs ingestion is independent of body weight. There is a need to work about origin, composition, interaction of MPs with biota and impacts of consuming fishes contaminated with high levels of MPs on human health. This is the preliminary study from the Karachi coast and will be a gateway for future studies in this area.

Detection of iodine in aqueous extract of plants through modified Mohr’s method

Abstract This article explores the extraction of iodine contents in Ipomoea pes-caprae plants using the modified Mohr’s method applied to a biological extract prepared in an aqueous solution. The plants were collected from three coastal regions of the Arabian Sea at Karachi coast, privileged as iodine resource areas. The size of the stem, leaves, and flowers of collected plants was measured after transportation into the laboratory before preparation of aqueous extract. It was found to be significantly different in size from each other. The electrical conductivity of the biological extract was recorded through a conductometer. For this purpose, the extract of different parts of the I. pes-caprae plants was prepared, followed by heating and filtration, while silver nitrate (AgNO3) was used as a precipitating agent. It was interesting to note that when filtrate was titrated with AgNO3, the precipitate started to settle down. Results showed the lowest iodine concentration in the flowers of all tested plants, followed by the highest in the leaves. Conductometric precipitation reaction was influential in determining iodine in herbal medicinal plants. It was observed that the size of the plants and collection sites impacted the iodine concentration. It was lowest in I. pes-caprae, collected from sea view Karachi, while highest in plants of Hawksbay. The endpoint of this biochemical reaction was taken when conductivity started rising. The standard curve of KI was prepared to determine the concentration of iodine in plant samples through conductometric titration. Moreover, the presence of Iodine was confirmed through a chemical testing method using HNO3, NH4OH, and H2SO4, after a complete precipitation reaction. The iodine quantification was done using a spectrophotometer through hexane solvent after being treated with H2SO4.

Potential of nitrification rate: in sediments of grey mangrove (Avicennia marina) located at different stations along Karachi coast, Pakistan

Potential of nitrification rate: in sediments of grey mangrove (Avicennia marina) located at different stations along Karachi coast, Pakistan

Analysis of Microplastic in Holothuria leucospilota (Echinodermata-Holothuroidea) and Sediments from Karachi coast, (Northern Arabian Sea)

Microplastics are found in all aquatic environments, and they can have several negative impacts on marine life. In this study, the distribution of microplastics in the sediment and in the organs (gut, respiratory tree, and tentacles) of sea cucumber (Holothuria leucospilota) collected from Mubarak Village and Cape Monze on the Karachi coast of Pakistan were investigated. The microplastic amount in different organs of H. leucospilota was found as 15.3-40.45 pieces/individual in the gut, 15.45-23.9 pieces/individual in the respiratory tree, 8.9-9.55 pieces/individual in tentacles. The microplastic amount of sediment samples was 57.40-129.35 pieces/kg. Fibers were the dominant microplastic type, up to 99% of all samples. The results of the present study show that the region is contaminated with microplastics both in biota and in sediments.

Re-description of two marine sponge species (Demospongiae: Haplosclerida) from the coast of Karachi, Pakistan, Northern Arabian Sea

Re-description of two marine sponge species (Demospongiae: Haplosclerida) from the coast of Karachi, Pakistan, Northern Arabian Sea

Alive and dead foraminiferal assemblages at sandy beaches of Karachi coast-diversity, ecological distribution and responses to seasonal fluctuations

Foraminifera are eukaryotic protists and play a vital role in marine community structure. However, how physicochemical environment shape meiofaunal community structure at highly dynamic exposed sandy beaches of Arabian sea is inadequately known. This is the first study about spatiotemporal distribution of alive and dead benthic foraminiferal (BF) species from coastal regions of Pakistan based on 48 core samples collected monthly with the help of hand corer (diameter = 3 cm) from four stations at two sandy beaches of Karachi coast i.e., Sandspit and Hawksbay. Sampling was done throughout the year from March 2013 to April 2014 to observe seasonal variability in southwest and northeast monsoon season. Physicochemical parameters (temperature, salinity, pH, dissolved oxygen and nutrients i.e. Ammonia, nitrate and phosphorus) and sediment characteristics (grain size, moisture content, organic content) was analysed using standard methods.The top 0–2 cm sediment slice was analysed for both living and dead foraminiferal assemblages. A sum of 6615 individuals (ind.) cm−2 of BF consisting of 3451 ind. cm−2 empty tests and 3164 ind. cm−2 living specimens belonged to 66 species were recorded, where 47% species are Miliolina, 42% Rotaliida, 9% Textulariina and 2% are Spirillinina. The similarity percentage breakdown analysis (SIMPER) showed 18.51% average dissimilarity between foraminifera abundance at Sandspit and Hawksbay but stations within sites showed similarity (82.83% at Sandspit and 84.65% at Hawksbay). The highest abundance of alive BF was recorded in northeast monsoon season (3232 ind. cm −2) associated with high levels of nutrients. Alive and dead foraminifera assemblages at Karachi coast do not seem to be measured by a single physicochemical and environmental factor but multiple factors are controlling spatiotemporal distribution of BF at these beaches. The most significant and governing factor for benthic abundance and diversity at these beaches is the monsoon season.

Seasonal Distribution of Benthic Foraminifera Associated with the Marine Sponge Liosina Paradoxa Thiele, 1899 at Sandspit Backwaters, Karachi, Pakistan

ABSTRACT Seasonal diversity and distribution of seven benthic foraminiferal species belonging to six families in association with the marine sponge Liosina paradoxa attached to pneumatophores of the mangrove Avicennia marina were documented at four sampling stations (St1–St4), Sandspit backwaters, Karachi coast during 2013. The calcareous species Ammonia sp. and Quinqueloculina laevigata were recorded at all stations in different seasons whereas the agglutinated species Ammotium cassis and Rotaliammina squamiformis were the most dominant species throughout the study. During the study period, water temperature ranged between 22.5–30.3°C, salinity ranged from 35–40, dissolved oxygen ranged from 0.11–3.45 mg L−1, and pH ranged from 7.15–7.69. The maximum relative abundance (45.65%) of foraminiferal species occurred at St2 from an exposed area while minimum relative abundances (13.04%) were recorded at St3 in sheltered areas. A K-dominance curve showed that highest frequency values in species were observed in the post-monsoon season as compared to the monsoon season. The present study is the first to report the foraminiferal assemblages associated with a marine sponge (Liosina paradoxa) from the mangrove habitat at Sandspit backwaters, Karachi.

Preliminary Observation on Microplastic Contamination in the Scombridae Species From Coastal Waters of Pakistan

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.

Vertical Ground Displacements and Its Impact on Erosion along the Karachi Coastline, Pakistan

This study employed remote sensing (optical and synthetic aperture radar) and data analysis techniques to quantify vertical ground displacements and assess their contribution to coastline erosion. To provide evidence from Pakistan, we selected the coast of Karachi—a mega-city located along the dynamic coastline of the Indus River Delta—which has been experiencing severe coastal erosion during the last few decades. Observations from the C-band Envisat/ASAR and Sentinel-1A sensors over the 2004–2010 and 2014–2016 periods, respectively, enabled us to study vertical ground displacements in the study area, providing a long-term assessment during 2004–2016. Results suggest that some areas along the Karachi coastline are subsiding at comparable rates to or even much higher than the relative sea-level rise (SLR, ~1.9 mm/yr), which may amplify the rates of relative SLR in coming years, along with accelerating coastal erosion. Various parts of the study area along the coast are unstable and undergoing displacement. Landsat images from 1989 to 2018 (10-year temporal resolution) were further used to examine the state of coastline erosion using three statistical approaches (i.e., End Point Rate (EPR), Linear Regression Rate (LRR), and Least Median of Squares (LMS)). While the erosion underlaid the majority of the eastern sections of the study area, the ground displacements were spatially heterogeneous across the study area and along the coastline. Erosion rates of ~2.4 m/yr spatially corresponded with ground displacement rates of up to ~−1.4 cm/yr, but not all the coastline segments with high annual mean erosion rates were associated with local mean subsidence. The causes of ground displacements and coastline erosion were analyzed, and results were interpreted by integrating spatial ancillary information. Results indicate that rapid urbanization, construction on reclaimed land, coastline erosion favoring seawater intrusion, failed drainage/sewerage networks, and soil liquefaction are contributing to the site-specific variations in the land displacement in Karachi.

Agar Extraction, Physical Properties, FTIR Analysis and Biochemical Composition of Three Edible Species of Red Seaweeds Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S. G. Gmelin)........

Three species of red algae Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S.G. Gmelin), Steentoft, L. M; Irvine and Farnham (formerly Gracilaria verrucosa (Hudson) were collected from four different sites (Buleji, Hawks Bay, Manora and Paradise Point) of Karachi coast. The G. corticata was the dominant species and the highest yield of agar was compared to other studied species. The physical properties such as gel temperature, melting temperature, density, viscosity and gel strength showed large variations. Interestingly, the gel temperature, melting temperature, density, and gel strength had the highest value in G. corticata samples collected, while gel viscosity recorded the highest value in G. dentata samples. Intensive spectroscopic FTIR analysis was determined in all three species of G. corticata, G. dentata and G. longissima. The bands at 414.7/cm to 3917.2/cm represents stretching and bending vibrations of alcohol O-H, amine N-H, alkane C-H, alkyne C=C, nitriles C=N, carboxyl C=O, nitro aromatic N=O, alkane C-C, nitro methane C-N, aliphatic amines C-N, sulfoxides S=O, alkene C-H alkyl halide C-Cl, C-I groups. The ash content of all studied species (G. corticata, G. dentata and G. longissima) was in the range of 20-30%, while the carbohydrate content was in the range of 22-24%. The results of this study suggested the utilization of our natural resources present in Karachi coast. This could be achieved by determining the quantity and quality of agar in the edible species of Gracilaria/Gracilariopsis.&#x0D;

Geochemical assessment of metal contamination in Manora picnic point sediment core from Karachi coast, Pakistan

Geochemical assessment of metal contamination in Manora picnic point sediment core from Karachi coast, Pakistan

Relationship between different linear dimensions of scale parameters of four species of Mugilidae from Karachi Coast, Pakistan

Relationship between different linear dimensions of scale parameters of four species of Mugilidae from Karachi Coast, Pakistan

Sediment Characterization and Monsoonal Impact on Beach Morphology at the Three Beaches along the Karachi Coast, Pakistan

Sediment characteristics plays important role in the determination and functioning of coastal ecosystems. The present study is an attempt to evaluate the variability in sediment characteristics of the three beaches: Clifton, Sandspit and Buleji, at the Karachi coast. The samples were collected during pre-monsoon and south-west monsoon seasons to evaluate the seasonal differences. The sediments of the three sites showed variations in moisture content, organic matter and grain size. The highest mean moisture (27.17%) and organic contents (3.5 %) were recorded from the sediments of Clifton. The maximum fraction of sediments (&gt; 80 %) consist of fine to very fine sand at all studied sites. The sediments of Clifton were high in very fine sand fraction and low in coarse sand fraction as compared to Sandspit and Buleji. The sediments of all the three studied sites are moderately sorted, negatively coarse-skewed and showed leptokurtic distribution. The studied beaches of Clifton, Sandspit and Buleji shows dissimilarity in sediment characteristics as indicated through Cluster and PCA analysis. The monsoonal influence on sediment characteristics was also observed at all the three studied beaches. The strong wave action during SW monsoon season results in the deposition of the coarser sediments at the high tide level thus increasing the steepness of the beaches.