New distribution record of a true coral species, Psammocora contigua (Esper, 1794) from Gulf of Kachchh Marine National Park & Sanctuary, India

Reef-building corals are generally confined to tropical waters across the world oceans. But some coral species are able to tolerate even inhospitable environments and suboptimal extremes, and form lower diversity reefs habitats such as the Gulf of Kachchh, located along the northwestern coast of India. Among the reported hard coral species so far from the Gulf of Kachchh, genus Psammocora is represented by only one species, P. digitata. The present study confirmed a new distribution record of Psammocora contigua from Narara Island. Due to the changing hydro-geographic conditions in the Kachchh region, ramose and branching coral species have been believed to be extinct completely, leaving no sign of live colonies. P. contigua, recorded during the present study is the only living species with ramose growth form recorded so far from the Kachchh waters. The present study also holds out hope to record more new coral species records from the region.

Characteristics of Irradiated Hydrogel Formulated from Composite i/k-carrageenan Combined with Polyvinyl Alcohol

Eucheuma seaweed from tropical waters habitat mainly contains carrageenan, a type of hydrocolloid potential for hydrogel production. This study aims to determine the characteristics of hydrogel formulated from composite i- and k-carrageenan combined with polyvinyl alcohol (PVA) which, could be used further for wound dressing application. The concentrations of composite i/k-carrageenan used were 1.0%, 1.5%, 2.0%, 2.5% and 3.0% w/w, and the PVA concentration was 12.5% w/w. Composite i/k-carrageenan in a proportion of 6:4 by weight. The hydrogel was irradiated using 60Co g-rays with the irradiation dose of 25 and 2 kGy.h-1. The concentration of composite i- and k-carrageenan influenced the gel fraction, water holding capacity, tensile strength, elongation, and surface morphology of the hydrogel. The optimum formula of irradiated composite hydrogel was obtained from 3.0% w/w of composite i/k-carrageenan. The formula had a gel fraction of 61.67%, water holding capacity of 1067.12%, tensile strength of 32.37 x 10-3 MPa, and elongation of 251.67%. Interestingly, the product with the optimum formula had a porous surface morphology and transparency, which are applicable for wound dressing purposes.

Free radical scavenging activity of five selected sea cucumbers collected from Lampung waters, Indonesia

Sea cucumber is an important raw material for food and remedy in the Eastern region. However, a study focusing on identifying the health benefit of sea cucumbers from tropical waters is still limited. A study on the free radical scavenging activity of five selected sea cucumbers collected from Lampung waters, Indonesia has been done. The objective of this study was to evaluate the free radical scavenging activity of five selected sea cucumbers, namely Stichopus vastus, Stichopus quadrifasciatus, Holothuria (Metriatyla) lessoni, Holothuria (Mertensiothuria) leucospilota, and Bohadschia marmorata. The extraction method which used in this study was the maceration method using methanol solvent while the free radical scavenging activity test is carried out using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) method. Compared to other species at a concentration of 250 µg/mL, S. vastus, S. quadrifasciatus, H. lessoni and H. leucospilota showed the strongest scavenging activity. While B. marmorata was classified as a very weak scavenging activity. It can be concluded that S. vastus, S. quadrifasciatus, H. lessoni H. leucospilota, and H. lessoni are important sea cucumbers from tropical waters as a source of natural antioxidant agents in the future.

Research of parasites with zoonotic potential for humans in skipjack tuna (Katsuwonus pelamis)

The skipjack tuna (Katsuwonus pelamis) is commonly found in the tropical waters of the oceans. It is a fishing resource of high economic value and available for national and international markets. Therefore, it is important to know the fish parasites for a correct sanitary inspection, as the pathogenesis in humans can occur through spoliative, toxic or mechanical action. This study aimed to identify the zoonotic parasitic fauna that infects the beautiful-striped using morphological methods. A total of 06 samples were analyzed. The fish were necropsied for parasitological evaluation of the musculature and internal organs. The samples were visually inspected and the structures with morphology combining with parasitic shapes were analyzed both in stereoscopic and microscope. The parasites found were fixed in 70% alcohol for later identification. All samples showed the presence of zoonotic parasites for humans. Two genera of zoonotic parasites have been found for humans that have beautiful tuna as their hosts, namely Anisakis sp. (Nematoda) and Trypanorhyncha (Eucestoda). A 100% of the infections occurred in the muscles and 66.6% in the liver. The results reinforced the importance of inspection by responsible organisms on the importance of evisceration as quickly as possible to avoid migration of larvae to the muscle.

Red Octopus, Octopus rubescens Berry, 1953 (Cephalopoda: Octopodidae), in the Mexican tropical Pacific

“Octopus” rubescens Berry, 1953 is an octopus of temperate waters of the western coast of North America. This paper presents the first record of “O.” rubescens from the tropical Mexican Pacific. Twelve octopuses were studied; 10 were collected in tide pools from five localities and two mature males were caught by fishermen in Oaxaca. We used morphometric characters and anatomical features of the digestive tract to identify the species. The five localities along the Mexican Pacific coast provide solid evidence that populations of this species have become established in tropical waters.

Redescription of Pomatostegus stellatus (Abildgaard, 1789) and P. kroyeri Mörch, 1863 (Polychaeta: Serpulidae) from the Tropical American coasts

Pomatostegus Schmarda, 1861 is a serpulid genus with three recognized species, mostly from tropical waters. Pomatostegus stellatus (Abildgaard, 1789), was described from the Caribbean Sea, and has been widely recorded in the Pacific and Indian oceans; P. kroyeri Mörch, 1863 was described from Puntarenas, Costa Rica; however, most records from the Tropical Eastern Pacific were referred to P. stellatus. In this work, the two species are redescribed using morphological characters. The main differences are in the shape of the Spirobranchus-type collar chaetae, opercular plate shape and the number of “free” circlets of spines without accompanying of opercular plates. Comments about characters of P. actinoceras Mörch, 1863, described from Philippines, and an identification key for the three species, are included.

The Occurrence and Distribution of Benthic Foraminifera in Tropical Waters Along the Strait of Malacca

Foraminifera are shelled single-celled protists that are found in all marine environments. Benthic foraminifera either live in sediments or attach to surfaces on the seafloor. Understanding the distribution and ecological response of benthic foraminifera is crucial, as they can indicate past and current ocean conditions. However, the benthic foraminifera distribution along the busy Strait of Malacca, which connects the Indian Ocean (north) to the Java Sea (south), is undersampled. In this study, we collected 24 surface samples from the northern Strait of Malacca to understand the distribution of foraminifera assemblages in shallow tropical waters. A total of 49 species of benthic foraminifera were identified. Calcareous hyaline species dominated the assemblages, with an extremely low occurrence of calcareous porcelaneous species. The common calcareous hyaline taxa were Asterorotalia pulchella, Pseudorotalia schroeteriana, Discorbinella bertheloti, Ammonia tepida, and Heterolepa praecincta. Cluster analysis categorised the foraminiferal assemblages into three major groups. The first cluster (Group A) consisted of a more diverse assemblage of hyaline and agglutinated species that inhabited a mean water depth of 45 m. The second cluster represented a population that inhabited deeper water environments (average water depth of 59 m). Finally, the third cluster (Group C) consisted of a foraminifera assemblage that inhabited shallow coastal environments (average depth of 22 m) with higher organic matter enrichment. The multivariate canonical correspondence analysis (CCA) showed that the foraminiferal assemblages reflected the shallow to deep water transition in the Malacca Strait. Water depth, which defines the depositional environment, had a greater influence on foraminifera distribution here than organic matter and salinity.

eDNA metabarcoding of small plankton samples to detect fish larvae and their preys from Atlantic and Pacific waters

Zooplankton community inventories are the basis of fisheries management for containing fish larvae and their preys; however, the visual identification of early-stage larvae (the “missing biomass”) is difficult and laborious. Here, eDNA metabarcoding was employed to detect zooplankton species of interest for fisheries from open and coastal waters. High-Throughput sequencing (HTS) from environmental samples using small water volumes has been proposed to detect species of interest whose DNA is the most abundant. We analyzed 6-L water samples taken from subtropical and tropical waters using Cytochrome oxidase I (COI) gene as metabarcode. In the open ocean, several commercial fish larvae and invertebrate species important in fish diet were found from metabarcodes and confirmed from individual barcoding. Comparing Atlantic, Mediterranean, Red Sea, and Pacific samples we found a lower taxonomic depth of OTU assignments in samples from tropical waters than in those from temperate ones, suggesting large gaps in reference databases for those areas; thus a higher effort of zooplankton barcoding in tropical oceans is highly recommended. This and similar simplified sampling protocols could be applied in early detection of species important for fisheries.