Quratulan Ahmed

Echinoderms are one of the major marine invertebrates that can be found on the ocean bottom at each sea profundity from the intertidal zone to the deep zone. There are 5 classes in the phylum Echinodermata (Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea and Crinoidea) even though members of the phylum share a fundamental structure, the biological characteristics of the classes vary greatly. Echinoderm samples comprising Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea and Crinoidea were collected from two unexplored sites Gariyan and Bandari beach along the Jiwani, Makran coast Balochistan. A total of 170 echinoderm specimens were collected during the present study from December 2021 to December 2022. In total, 21 echinoderm species were identified, representing five distinct classes: Holothuroidea (8 species), Asteroidea (7 species), Ophiuroidea (3 species), Crinoidea (2 species) and Echinoidea (1 species). This study significantly expands the documented occurrence and abundance of these taxa along the Makran coast, providing an essential ecological baseline for future biodiversity research and conservation efforts in the region.

A new species, Actinopyga atypica sp. nov., in the sea cucumber family Holothuriidae, plus two new holothuroid records from the Pakistan coastal waters are here described. The new species differs from all known species of Actinopyga in possessing a cucumariid-type of calcareous ring accompanied by slender, straight, terminally forked rods in the body wall, unlike the thick, usually well-branched rods of other species of the genus, setting it apart from all known congenerics. Of the two additional records one is another holothuriid herein attributed to the Indo-West Pacific species Holothuria (Selenkothuria) erinacea Semper, 1868. It is suspected to be a juvenile of this species in possessing, in addition to the perforated rods and plates in the body wall, well-formed tables, suspected to be a juvenile character, as pertains in its consubgenerics H. (S.) parva Krauss (in Lampert, 1885) and H. (S.) moebii Ludwig, 1883. The third species is a thyonid, Thyonina bijui Thandar, 2017, belonging to the family Thyonidae (sensu Smirnov 2012), originally described from Kerala, India.

The present study provides the first comprehensive morphological and taxonomic account of Salmacis bicolor L. Agassiz in L. Agassiz & Desor, 1846 from Pakistan, based on recently collected specimens from the intertidal rocky shore of Manbar Island along the Makran coast, Balochistan. Although earlier reports documented the occurrence of this species in Pakistan, subsequent works either omitted it or offered only photographic records without accompanying morphological descriptions. The examined specimens exhibit diagnostic characteristics consistent with global accounts of the species, including a hemispherical to subconical test; interambulacral plates with zig-zag sutures; crenate but non-perforated tubercles arranged in horizontal series; and cylindrical, finely striated spines, banded in red with yellowish, violet, or green hues, typically with red bases. These observations confirm the presence of S. bicolor along the Makran coast and constitute the first verified morphological description of the species from Pakistan. This study not only substantiates earlier fragmentary records but also contributes to the expanding baseline knowledge of echinoid diversity in the northern Arabian Sea, highlighting the need for further investigations that integrate both morphological and molecular approaches.

The available information regarding bryozoans in coastal areas of Pakistan is limited. This research paper presents the first record of Calyptotheca alexandriensis from Ras Juddi (Pasni) along the Makran coast, and the second record globally of this species. This species was first reported in the Eastern Harbor of Alexandria, Egypt, as a distinctive deep orange erect foliaceous bryozoan and was observed abundantly on various hard substrates, such as rocks, ropes, metal pipes supporting marina piers, and ship hulls. The discovery adds a new record of the family, Lanceoporidae, and genus, Calyptotheca, to the bryozoan fauna of Pakistan, expanding its known distribution to the Northern Arabian Sea. The present specimens were collected during December 2021–October 2022 and subjected to detailed taxonomic analysis using light microscopy and scanning electron microscopy (SEM). This study contributes to the understanding of bryozoan biodiversity in the region and highlights the potential for further discoveries along the unexplored coastal areas of Pakistan.

Microplastics (MPs) are posing an increasing threat to the marine environment, affecting marine ecosystems and posing potential risks to human health through the food chain. This study aims to investigate the MP contamination of Holothuria (Thymiosycia) arenicola Semper, 1868, Holothuria pardalis Selenka, 1867, sediments and seawater from Buleji coasts of Karachi, Pakistan. The MP contamination was determined in the different body parts of sea cucumber species and both seawater and sediment samples were contaminated with microplastics. The results show that H. arenicola contains more microplastics than H. pardalis. In terms of shape and colour, fibres were the most common form of MPs (>99%), with black being the predominant colour. The highest to the lowest amount of MPs was determined as gut (52±26 pieces/individual in H. arenicola and 31±14 pieces/individual in H. paradis), coelomic fluid (18±10 pieces/individual in H. arenicola and 26±15 pieces/individual in H. paradis), respiratory tree (22±11 pieces/individual in H. arenicola and 14±9 pieces/individual in H. paradis and tentacles (13±8 pieces/individual in H. arenicola and 10±5 pieces/individual in H. paradis), respectively. Determination of MP pollution in these sea cucumbers and their surrounding environment is very important in terms of the importance of these organisms in the marine ecosystems. The biological impacts of MPs on sea cucumbers and other marine organisms can eventually affect humans through the food chain. Therefore, the paper advocates for the development of policies to monitor and reduce MP pollution in marine ecosystems.