Showing papers in "Thalassas: an International Journal of Marine Sciences in 2021"

Community Structure and Spatial Patterns of Soft-Bottom Macrozoobenthos in Oualidia Lagoon, Moroccan Atlantic

Abstract: The paper analyses the composition, structure and spatial organization of the soft-bottom macrozoobenthos inhabiting Oualidia lagoon (Moroccan Atlantic coasts), as well as their relationships with the main environmental variables. Material for the study was collected from 43 stations in winter 2013. A total of 56 taxa belonging to 6 phyla were recorded. Species diversity showed the highest values for molluscs, crustaceans and polychaetes. We used a Hierarchical Ascending Classification and a non-Metric Multidimensional Scaling to characterize the macrozoobenthos of the lagoon. We identified three groups of stations according to the outer, middle and inner part of the lagoon, hosting arranged from the outer -most to inner-most areas of the lagoon. The trophic structure of the macrozoobenthos was dominated in density by deposit-feeders (88.1%) and species richness by carnivores (20%) and detritivorous (20%). The BIO-ENV analysis showed that the combination of granulometry, salinity and temperature were the major factors controlling the spatial distribution of the macrozoobenthos in the Oualidia Lagoon.

Identification of Bioactive Compounds and Evaluation of the Antimicrobial and Anti-biofilm Effect of Psammocinia sp. and Hyattella sp. Sponges from the Persian Gulf

Abstract: Biofilms are microbial communities that bind to surfaces resist adverse conditions. Increasing the survival of bacteria in biofilm structures compared to their planktonic form causes problems in drug treatment. On the other hand, drug resistance in the world is increasing and the need to discover and identify new compounds with the antimicrobial effect is felt. Marine sponges are adapted to unique marine environments and can fight pathogens of these ecosystems without having a dedicated defense system. This study aimed was to investigate the antimicrobial and anti-biofilm effects and also to identify the bioactive compounds of two samples of Psammocinia sp. and Hyattella sp. sponges. Six bacteria Pseudomonas aeruginosa, Acinetobacter baumanni, Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus and Bacillus cereus were tested. The extract was first extracted using dichloromethane and methanol (DCM: MeOH) (1:1 v/v) solvents. The planktonic form was investigated using Disk diffusion and agar well diffusion methods. The minimum inhibitory concentration (MIC) was determined by the microdilution method and then the minimum bactericidal concentration (MBC). Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS) were performed to identify the compounds of each extract. No zone of inhibition (ZOI) was observed on the planktonic form of K. pneumonia due to both extracts. MIC have about 10 to 20 mg/ml and MBC in about 20 to 80 mg/ml was determined. The results showed that the effect of both extracts on the degradation of the biofilm formed by B. cereus was less than other bacteria. The results of GC-MS showed the presence of phenol, butanedioic acid, propanoic acid and Benzeneacetaldehyde compounds. This study showed that marine sponges at the Persian Gulf can be a good candidate for the extraction of bioactive compounds that use as antimicrobial agents.

Feeding Ecology of Thornback Ray, Raja clavata (Linnaeus 1758) in Gokceada Island, Northern Aegean Sea, Turkey

Abstract: The dietary composition and nutritional alteration resulting from time and size of thornback ray, Raja clavata, were investigated in the present research. For this purpose, the individuals were obtained from the commercial bottom trawl vessels operated around Gokceada Island, North Aegean Sea, Turkey between February 2019 and February 2020. The female:male ratio was found to be 1:0.79. The vacuity index was calculated for males, females and both individuals to be 5.8%, 4.7%, and 5.3%, respectively. The major food item groups were determined to be decapod crustaceans, teleost fish, and cepholopoda with IRI% (Index of Relative Importance) values of 77.72, 7.05, and 0.25, respectively. The best-represented food item was found to be Goneplax rhomboides. The prey types, abundance, and biodiversity were observed to change with the increasing lengths of R. clavata. The trophic level (TLw) of R. clavata was calculated to be 3.27, and it was observed that the TLw values were increased with the increasing individual length. The diet overlap was found to range from 40 to 49 cm and 50 to 59 cm TL in autumn and winter. The highest prey biodiversity was found in the length group of 70–85 cm TL and during spring. This study presents detailed findings on the feeding behaviour of R. clavata. In the future, food competition between the species should be monitored to develop a better understanding of the diet overlap. Thus, more comparisons should be conducted between the studies performed in varied geographical areas.

Sulfated Triterpene Glycosides from the Saudi Red Sea Cucumber Holothuria atra with Antioxidant and Cytotoxic Activities

Abstract: The bioactive constituents of sea cucumber Holothuria atra were investigated, and four sulfated holostan-type triterpene glycosides (1–4) along with other seven know metabolites were obtained. On the basis of the extensive NMR and ESI-MS data, the structures of triterpenoid saponins were assigned as a new compound echinoside B 12-O-methyl ether (1), and known echinoside B (2), 24-dehydroechinoside B (3), and holothurin B (4). The extract and isolated saponins displayed weak antioxidant DPPH radical scavenging activities, where echinoside B (2) showed the highest value at 26.41%. However, 24-dehydroechinoside B (3) showed mild antioxidant-reducing power activity (0.19 nm), compared to the synthetic antioxidant (BHT). Both compounds 2 and 3 exhibited moderate cytotoxic activity by reducing the viability of Ehrlich ascites carcinoma cells to 41.0% and 42.2%, respectively, compared to the drug control vincristine (95.2%).

First Report of Conger Eel (Anguilliformes: Congridae) Ariosoma majus (Asano, 1958) From Indian Ocean

Abstract: Present paper reports Ariosoma majus (Asano, 1958) for the first time from the Indian Ocean on the basis of three specimens (TL: 246–290 mm) collected from Deshpran Fishing harbor, West Bengal, India. Current study compares morphometric measurement and meristic counts of the specimens from the Indian Ocean and the Pacific Ocean.

Length–Weight Relationship of some Discarded Fish Species with Emphasis on Length at Maturity from the Central Aegean Sea, Turkey

Abstract: In this study, length–weight relationships were estimated for discarded trawl fish species and mean size at capture was compared with reported mean length at first maturity (Lm). Sampling was conducted in Sigacik Bay, on the Turkish coast of the central Aegean Sea, between October 2008 and April 2010 onboard a commercial trawler fishing over a depth range of 88–450 m. A total of 14,120 individuals from 15 fish species belonging to 13 families were examined: 9 species were elasmobranchs and 6 were teleosts. Length-weight relationship (LWR) values of b parameter varied between 2.55 and 3.37, with five species having isometric growth, five negative and six positive allometric growth. LWR was not determined for one species due to insufficient sample size. Average size at capture for 14 fish species was found to be below the reported Lm. Our results could be useful in stock assessments and serve as a reference for future comparison of similar parameters estimated in other parts of the Aegean Sea or Mediterranean. Furthermore, information on the discard species in the trawl fishery, their mean size at capture and conservation status is important when considering sustainable ecosystem based fishery management.

Identification and Sexually Dimorphic Expression of a FoxL2-like Gene in Mud Crab ( Scylla paramamosain ): Potential Roles in Male Differentiation and Development

Abstract: Monosex breeding technology has received enormous attention for the Scylla paramamosain, an economic crustacean species with distinctive sexual dimorphism. However, the molecular mechanism of gonadal development and sexual differentiation still remain inconclusive. In this study, we reported the cloning, characterization of a FoxL2-like gene with male-biased expression in the mud crab (SpFoxL2). The SpFoxL2 encoded a putative forkhead-box protein with 352 amino acids. Phylogenetic tree revealed the SpFoxL2 was clustered with the invertebrates FoxL2 homologues, most closed to E. sinensis. By quantitative real-time PCR, it was shown that the SpFoxL2 was expressed in intestine, ovary and testis, with the highest expression level in testis. During gonadal development, the expression level of SpFoxL2 in ovary was lower than that in testis at all stages. The expression level of SpFoxL2 constantly declined from stage I to stage V in ovary. While, there is a rising tendency from stage I to stage IV in testis. Notably, this male-biased expression pattern could be detected as early as the juvenile crab stage I (CI stage) before morphological sexual differentiation in the mud crab. By fluorescence in-situ hybridization, SpFoxL2 mRNA was found located in both somatic and germ cells in gonads. In testis, it was most strongly localized in the meiosis germ cells (spermatocytes). While in ovary, the signal became weaker in the meiosis germ cells (oocytes). The results imply that the SpFoxl2 may play an important role in male differentiation and development, laying a foundation for future research on sexual differentiation of the species.

DNA Barcoding of the Family: Leiognathidae in the Water of Bay of Bengal, Odisha Coast, India Based on 16s rRNA and COI Gene Sequences

Abstract: This study reports the DNA barcoding of the species of the family: Leiognathidae found along the Bay of Bengal, Odisha coast to understand their molecular phylogeny and check whether the molecular data congruence with the morphological delineation or not. Next generation sequencing (NGS) platform was used to carry out the sequencing of both cytochrome c oxidase subunit I (COI) and 16s ribosomal RNA (16s rRNA) genes of 11 species of the family collected during the study period. Each sequence obtained were validated by comparing with at least 2 to 4 other similar sequences retrieved from NCBI for both the genes through Kimura two Parameter model (K2P) distance and Maximum Likelihood (ML) tree analysis. The species delimitation analysis using Assemble species by automatic partitioning (ASPA) was also conducted to detect the species boundaries and support the above finding. The clade proposed for the family Leiognathidae using bacterial mediated light organs matches more closely with the clade obtained through 16s rRNA genes ML tree analysis than COI genes ML tree. The confusion between Deveximentum interuptum, Secutor ruconius and Secutor megalolepis with rational analysis based on both 16s rRNA and COI genes were also analysed.

Size Frequency, Length-Weight, and Length-Length Relationship of Bearded Worm Goby Taenioides cirratus (Blyth, 1860) from the Noakhali Coast, Bay of Bengal

Abstract: Size frequency, length-weight relationships (LWRs), and length-length relationships (LLRs) for an estuarine fish Taenioides cirratus (Blyth, 1860) from the Noakhali coast, Bay of Bengal was studied. Specimens were caught with the fixed purse net of two mesh sizes (0.2 to 0.5 in. and 2.0 to 2.5 in.) from March to July 2019. The maximum total length for male T. cirratus (36.2 cm) reported in this study is a new record for this species. The length-weight relationships for male, female, and unsexed T. cirratus was highly significant (p < .001), and adjusted r2 values were 0.967, 0.922 and 0.955 for males, females, and unsexed, respectively. The calculated growth coefficient (b) for male, female, and unsexed T. cirratus was 2.546, 2.948, and 2.618, respectively. The length-length eq. TL = 1.1974 SL + 0.4403 for the males and TL = 1.1712 SL + 0.7096 for the females were highly significant (p = 0.001, r2 ≥ 0.978 for both males and females). Our estimated LWRs and LLRs parameters for male and female T. cirratus can be useful for the management and conservation purpose of this species.

Length–length and Length–weight Relationships for Four Dominant Small Pelagic Fishes in the Kuroshio–Oyashio Current System

Abstract: Length–length and length–weight relationships in various length measurement standards were estimated for dominant small pelagic fishes in the Kuroshio–Oyashio current system (Japanese sardine Sardinops melanostictus, Japanese anchovy Engraulis japonicus, chub mackerel Scomber japonicus, and spotted mackerel Scomber australasicus). Fish samples were collected from surface–midwater trawl surveys and commercial purse-seine fisheries between September and October of 2020 in the western North Pacific. Total length (TL), fork length (FL), and standard length (SL) were measured to 0.01 cm, and total body weight (W) was measured to the nearest 0.01 g for each individual. All length–length relationships (TL–FL, TL–SL, and FL–SL) were highly significant (p 0.98 in all species. Length–weight relationships (W–TL, W–FL, and W–SL) were also highly significant (p 0.98 in all species. This study provides new comprehensive information on length–length and length–weight relationships in various length measurement standards for the four small pelagic fish species. These data will be useful references for biological studies and stock assessments of these small pelagic fishes.

A Spatial Ecological Study Based on Benthic Foraminifera off Central West Coast of India: An Approach through Cluster Analysis with Special Reference to Oxygen Minimum Zone

Abstract: Fifty-two surface samples collected from a depth range between 15 and 3300 m from the Vijaydurg-Karwar sector off the central west coast of India were analyzed for benthic foraminifera. A total of 386 benthic foraminifera were identified to species level. The relative abundances of 21 major genera (>5% in at least two stations) were plotted on a distribution map as well as on a kite diagram. Most of the genera show correlation to water depth in the study area. For better understanding and to draw meaningful conclusions from the assemblages out of the surface distribution of major genera, Q-mode cluster analysis was performed with the total number of species as variables. The clusters (namely A & B) and their subclusters (namely B1, B2 & B3) also exhibit a preference to water depth. Considering the position of the Oxygen Minimum Zone (OMZ) in this region extends from 150 to 1500 m water depth, it was noticed that the stations in smaller subcluster within cluster B3 fall below the OMZ, while most of the stations in cluster B2 fall above the OMZ. From the cluster analysis, the major benthic foraminiferal species from within the OMZ are identified as Bolivina silvestrina, Bulimina marginata, Globocassidulina oriangulata and Melonis pompilioides. Hence, cluster analysis based on the benthic foraminiferal assemblage is useful to detect the position of the OMZ in the study area.

Determination of Fishing Grounds Distribution of the Indian Mackerel in Malaysia’s Exclusive Economic Zone Off South China Sea Using Boosted Regression Trees Model

Abstract: With the ongoing climate change affecting the ocean, there is a need to understand and predict the future distributions of marine species in order to assess the sustainability of marine ecosystem. In this study, remotely-sensed satellite oceanographic data together with Indian mackerel (Rastrelliger kanagurta) fishery dataset were used to predict potential fishing grounds in the Exclusive Economic Zone (EEZ) of Peninsular Malaysia using boosted regression trees (BRT) model. The model was developed using three years (2008–2010) fish catch data and environmental variables of chlorophyll-a (chl-a), sea surface temperature (SST) and sea surface height (SSH). Result indicated that potential fishing grounds were closely associated with SSH, followed by SST and chl-a. The performance of the BRT model indicated acceptable fishing grounds prediction accuracy (AUC value of 0.749). Seasonal variability in fishing grounds was related to favorable environmental conditions of SSH (1.1–1.3 m), SST (29–32 °C) and chl-a (0.3–0.6 mg/m3). The projection of increases in SST due to climate change according to IPCC-AR5-RCPs was observed to influence the spatial and temporal distributions R. kanagurta. Increased temperature at 1.80 °C resulted in high potential catch areas for R. kanagurta in the EEZ. Meanwhile, elevated temperature at 2.60 °C and 3.30 °C showed decreased in potential catch areas for R. kanagurta in the EEZ. Most of the future fishing grounds area were projected to decline, and it was observed to shift outside the EEZ off South China Sea. Hence, by understanding these relationships, this analysis identifies where strategies can be adapted to face the ecological impacts under changing environmental conditions.

First Insight into the Biological Aspects of the Crocodile Shark Pseudocarcharias kamoharai in the Eastern Pacific Ocean

Abstract: The crocodile shark Pseudocarcharias kamoharai (Matsubara, 1936) is a species caught incidentally off the coast of Ecuador with no commercial importance in the country. As with many elasmobranch species, very little is known about its general biology. The aim of this study was to provide baseline information to enhance the knowledge on various aspects of the biology of this species. During the years 2003–2009, a total of 59 individuals of P. kamoharai were landed by commercial fishing in Ecuadorian waters. The total length (TL) ranged 50–113 cm. On average, the females were larger than males (91.8 ± 2.2 and 84.1 ± 4.1, respectively) and the number of females captured was higher (sex ratio = 1.9F:1M). Based on the morphology of the claspers, males were considered mature at 80 cm TL and at a clasper length of 6 cm, and 70% of the males caught were mature. The squid Ancistrocheirus lesueuri was the only prey observed in two shark stomachs with food from 59 shark stomachs analyzed. This study provides biological information of P. kamoharai in Ecuador and will help as a baseline to generate data and increase our knowledge of the biology of this shark species in the eastern Pacific Ocean.

Temporal Dynamics of Fishing Affect the Biodiversity of Macrobenthic Epifaunal Communities in the Coastal Waters of Ningbo, East China Sea

Abstract: Spatio-temporal patterns of macrobenthic epifaunal communities with fishing disturbances indicate that the fishing process directly leads to a decrease in diversity and substratum sediment homogenization. However, it has not yet been explored exclusively at the community reconstruction dynamic level with fishing changes over time. This study monitored the macrobenthic epifaunal communities during the implementation of a fishing moratorium policy in order to elucidate the fishing-driven variations in the macrobenthic epifaunal communities. Bottom trawl surveys were conducted before (BEF), during (DUR), and after (AFT) a summer fishing moratorium. During each survey, macrobenthic species and surface sediment samples were collected from two transects located at two different depths. The results showed that the communities in the DUR phase were undisturbed, while the communities were disturbed in both the BEF and AFT phases. Compared with the BEF and AFT phases, there was an abundance of peak spawning species as well as the impact on macrobenthic communities in relation to the lightened fishing disturbance, significant increases in species richness, abundance, and biomass were observed in the DUR phase. Prohibition of fishing during summer facilitates the resilience of macrobenthic communities by maximizing spawning and reducing bottom disturbance to larval, thereby enhancing overall fishery resources.

The Influence of the Macroalgae Liquid Extracts on the Pigments and Fatty Acids Profile of the Marine Microalga, Picochlorum maculatum (PSDK01)

Abstract: The present study was aimed to evaluate the effect of macroalgal liquid extract (MLE) on the growth, biomass, pigments and proximate composition in the Picochlorum maculatum cells. The water extracts of the seaweeds; Padina gymnosphora, Halimeda macroloba, Caulerpa serrulata, Ulva intestinalis, and Halimeda opuntia of the Mandapam (Southeast coast of India) were assessed for their growth enhancing property in microalga. Further, during the present experiments, an attempt was made for the formulation of an eco-friendly and low-cost, new microalgal – culture medium with the macroalgal liquids along with the minimum quantity of chemicals and commercial fertilizers And the present artificial culture media composition included 30 different combinations (except control) of chemicals (sodium nitrate, sodium ortho phosphate) and commercial fertilizers (urea, super phosphate, ammonium sulphate) along with five macroalgal liquid extracts. The experimental results suggest that the P. maculatum can be successfully grown under the newly formulated MLE-medium along as compared to that of expensive whole medium. The growth (0.12 abs), biomass (2.05 g L−1), chlorophyll ‘a’ (2.05 µg/ml), chlorophyll ‘b’ (1.55 µg/ml), total carotenoids (141.98 µg/ml), total fatty acids (76.82%), and total amino acids (92.56%) were found to be comparatively higher in Ulva intestinalis + Ammonium Sulphate (UI + AS) combined medium than through the whole medium (control) cultured P. maculatum cells. This study clearly underlines the prospect of using MLE as an alternative nutrients supplier to stimulate the growth of microalga that would be an important development in aquaculture feed industry.

Vegetative and Sexual Reproduction of Bloom-forming Dinoflagellate Noctiluca Scintillans (Ehrenberg) McCartney from Tropical Cochin Estuary (Southwest coast of India): In-situ and Laboratory Studies

Abstract: The lifecycle of red tide forming dinoflagellate Noctiluca scintillans (Ehrenberg) McCartney was investigated from the estuarine waters of Cochin and also from their clonal cultures. Reproductive divisions including asexual binary fission and sexual isogamete formation were studied. Certain vegetative cells were observed to undergo binary fission. Gametocyte mother cells underwent meiosis followed by several synchronous mitotic divisions which resulted in the production of 256–1024 mature spindle-shaped haploid isogametes attached on the surface of the gametocyte mother cell body. After several hours, gametes were observed to fuse and form diploid zygotes. The zygote underwent differentiation from spindle to spherical, with a reduction in the flagellar number and develops into a minuscule trophont. These trophonts later attained maturity as the cell size increased. The life cycle of Noctiluca scintillans thus appear to be a diplontic type. Hence, the study illustrates different life cycle stages of N. scintillans based on both in-situ and clonal culture studies. In-situ life cycle study is first of its kind in the reproductive biology of the species.

Four New Records of Brachyuran Crabs (Crustacea: Decapoda: Brachyura) from India

Abstract: The present study is a part of long term ongoing study on brachyuran crab diversity of India. The specimens were collected from intertidal zone as well as from the fisheries by-catch captured using commercial trawler. The specimens were identified up to species level using standard literature. From the collection, four species of brachyuran crabs, Schizophrys pakistanensis Tirmizi & Kazmi, 1995 (Majidae), Macromedaeus voeltzkowi (Lenz, 1905) (Xanthidae), Pseudosesarma brehieri Ng, 2018 (Sesarmidae) and Ilyograpsus paludicola (Rathbun, 1909) (Macrophthalmidae) are first time reported from India. The present study records significant expansion in the distribution range of these species. The diagnostic characteristics and remarks on the taxonomy and distribution of each species are given in this paper.

The Application of Erythromycin, Elbayou, and Rica-1 Probiotic in the Rearing of Scylla paramamosain Mud Crab Larvae Development into the Crablet Stage

Abstract: Antibiotics, chemicals, and probiotics are often used in aquaculture activities to successfully culture species. The purpose of this study was to compare the effectiveness of the application of erythromycin, elbayou, and Rica-1 probiotic in the rearing of S. paramamosain mud crab larvae development to the crablet stage. The newly hatched healthy larvae zoea-1 were cultured in nine fiber tanks with a volume of 200 L each at the density of 80 ind. L−1. The three treatments tested consisted of A) Erythromycin; B) Elbayou; and C) Rica-1 probiotic with a dose of 15 mg L−1 each. Each treatment with three replications. Several parameters were monitored including the larvae density, larvae stage development, and water quality parameters such as ammonia, nitrite, total organic matter (TOM), Vibrio sp, and total bacteria population. At the Day of Rearing (DOR)-15, the larvae developed into zoea-5 with a density of 15.3 ± 2.1 ind. L−1 (A); 16.3 ± 2.5 ind. L−1 (B), and 7.3 ± 1.5 ind. L−1 (C). At DOR-19, some larvae zoea-5 successfully metamorphosed into the megalopa stages. The crablet-D15 production in erythromycin treatment was 141.2 ± 34.1 ind. tank−1, significantly different (P < 0.05) from the Elbayou treatment production of 70.0 ± 3.74 ind. tank−1. However, there was no significant crablet production from the RICA-1 probiotic treatment due to megalopa's death as a consequence of Vibrio harveyi infection. As a result, the erythromycin application of 15 mg L−1 was the most effective for increasing crablet production in rearing mud crab larvae.

Length Weight Relationships and Form Factor of 8 Marine Fishes from the Bay of Bengal

Abstract: Length weight relationships (LWRs) and form factor of 8 marine fishes were assessed from the Bay of Bengal, Bangladesh through sampling from November 2019 to October 2020 with gill net (mesh size, 3-6 cm). Body weight was weighed with 0.01 g precision and total length was measured nearest to 0.1 cm. Our study provided LWR of Scomberomorus koreanus for the first time. LWR of Drepane punctata, D. longimana, Scatophagus argus and Ephippus orbis were documented for the first instance from the Bay of Bengal. Values of b for LWR ranged from 2.574 (Thryssa setirostris) to 3.380 (Drepane longimana) with r2 ≥ 0.948 as well as form factor ranged from 0.0062 (S. koreanus) to 0.0313 (Drepane punctata). Findings of our study will be helpful for sustainable management of these eight marine fish species in the Bay of Bengal.

Benthic Index for Estimating Food Availability in Two Soft Bottoms Fishing Areas

Abstract: Based on the role of mollusks in trophic webs, this study aimed to implement a benthic food availability index (BFAI) estimated from soft-bottom benthic mollusks in fishing areas. Two lobsters fishing regions, Caibarien and Batabano, were sampled. The design of BFAI was based on the densities, biomasses, and species richness of mollusks at eight sites in each region. Mollusks and benthos communities (> 4 mm) were sampled by dredging. Spatial effectiveness of BFAI was tested comparing among sites and regions. Temporal effectiveness was tested comparing BFAI between Past period (1981–1985 in Batabano and 1989–1990 in Caibarien) and Current data (2015 in Caibarien and 2015–2018 in Batabano). BFAI was regressed with Shannon-Weiner diversity and species richness indices. BFAI average in Caibarien (2015) was 0.90. In Batabano it was 0.64 and 1.09 for 2015 and 2018 respectively. In both regions BFAI varied among sites and shows a significant temporary decrease, going from "Good" in the Past to "Fair" in the Current. No differences were found between regions, but spatial distribution of BFAI values ​​corresponds to the biotic potential (density, biomass, and species richness of benthos), which suggests the certainly of BFAI detecting the benthic community variations that affect the food availability. Regression coefficients were significant in more than 60% of the cases being between 0.701 and 0.978. BFAI showed greater values where lobsters catches have been usually higher, it means that BFAI constitute another environmental explanation for lobster abundance decrease at natural fishing areas.

Checklist of Parasitic Isopods (Crustacea: Isopoda) Infesting Marine Decapod and Fishes Off Mexico’s Coasts

Abstract: Herein, a checklist of parasitic isopods infesting marine decapod and fishes off Mexico’s coasts is presented. Using information based upon a thorough review of published papers in databases, the checklist was structured by order, suborder, superfamily, family, and species of isopods, along with host species, attachment site and damage in the host, and the locality. A total of 33 parasitic isopod species were listed, with 24 species of the family Bopyridae infesting 30 decapod species and 9 species of the families Aegidae, Ancinidae, and Cymothoidae infesting 18 fish species. Regionally, the Bopyrid species were reported from the southern Gulf of Mexico, from Veracruz to Yucatan, with 11 species, the Mexican Caribbean, Quintana Roo, with 7, and the Mexican Pacific, from the Gulf of California to Guerrero, with 3 species. The Cymothoid species were reported in fish hosts from the southern Gulf of Mexico with 7 species, and Mexican Pacific with 2 species. The low number of parasitic isopod species presented in this checklist calls the attention to examine more host species, including commercially important fish.

First Record of Deepwater Scorpionfish Phenacoscorpius adenensis (Teleostei: Scorpaenidae) from India, Central Indian Ocean

Abstract: Phenacoscorpius adenensis Norman 1939, a rare deepwater scorpionfish was collected from Kavaratti Island, Lakshadweep Archipelago, and reported for the first time from the Central Indian Ocean and Indian waters. P. adenensis, which is morphologically similar to many closely related species, is described, and the specimen is preserved, catalogued and kept in reference museum.

Spatial Variations in the Stocks of Randall’s Threadfin Bream, Nemipterus randalli Russell 1986 Along the Indian Coast Inferred Using Body and Otolith Shape Analysis

Abstract: Nemipterus randalli is one of the predominant species in demersal fisheries along the Indian coast. Analysis of morphological divergence among the stocks using different stock identification methods provides a basis for sustainable resources management. In the present study, body and otolith shape was used to elucidate the stock structure of Randall’s threadfin bream. Specimens of N. randalli were sampled from five major fishing regions across the Indian coast from September 2018 to November 2018. A total of 23 truss distances and six otolith shape indices from each specimen were extracted and analyzed using multivariate statistical analysis. Body and otolith shape analysis suggested the existence of different phenotypic stocks of N. randalli along the Indian coast. Phenotypic variations among the stocks might be probably due to the existing environmental conditions in their respective habitats. Therefore, there is a need for independent management approaches for different stocks of N. randalli. Further, complete understanding of the temporal variation of stocks in the future could be useful in managing the fishery resource.

New Geographical Record of the Rainbow Runner, Elagatis bipinnulata (Quoy & Gaimard, 1825) (Perciformes: Carangidae) from the Bay of Bengal, Bangladesh

Abstract: This paper describes the first record of the rainbow runner Elagatis bipinnulata (Perciformes: Carangidae) from Cox’s Bazar, the North eastern part of Bay of Bengal, Bangladesh. Two specimens of E. bipinnulata ware collected on 23 June 2018 from the Bangladesh Fisheries Development Corporation Fish Landing Center of Cox’s Bazar. Morphometric and molecular approaches were applied for identification. Dorsal and anal fins with terminal two rayed finlet, absence of scute, upper jaw ending distinctly before vertical at front margin of eye are the key characteristics to this species. Six spines in first dorsal fin and (24 + 2) fin rays in second dorsal fin; (17 + 2) anal fin rays with one spine present. The morphometric, meristic and molecular analyses thus confirmed the presence of E. bipinnulata in Bangladesh. This report updates the geographical distribution for this species confirming its presence in the coastal region of Bangladesh, and extends the number of marine fish known from the area.

Potential Role of Major Phytoplankton Communities on pCO2 Modulation in the Indian Sector of Southern Ocean

Abstract: Spatial variations in the phytoplankton community compositions, carbon dioxide system and ancillary water column properties, were monitored across various frontal systems in the Indian Sector of Southern Ocean (ISSO) during austral summer 2013. Four major frontal systems, namely, the Agulhas Return Front (ARF), Southern Subtropical Front (SSTF), Subantarctic Front (SAF) and Polar Front (PF) were identified along the study area. Major groups of phytoplankton were distinguished adopting single marker pigment approach. Statistical computations showed the distribution of diatoms were influenced by the availability of inorganic nutrients (primarily silicate and nitrate) and mixed layer depths (MLD). Haptophytes were strongly dependent on phosphate availability, whereas, picoplankton flourished in water where regenerated nutrient ammonium was present. The lowest surface pCO2 (267.26–291.5 µatm) along with in situ oxygen production (> 10 µM) was encountered at the two warmer fronts, ARF and SSTF, dominated by haptophytes and picoplankton. The colder Antarctic fronts, SAF and PF were dominated by diatoms where surface pCO2 was relatively higher (> 350µatm). Poor statistical correlation among temperature and total chlorophyll with pCO2 revealed complex interplay of multiple factors. Contribution of major phytoplankton groups towards pCO2 drawdown was computed using a one-dimensional model describing the relative contributions of biological activities. In ISSO, calcifying and photosynthesizing haptophytes were observed to play a crucial role in the “biological pump” of CO2 drawdown at ARF, SSTF and SAF, while the silicifying micro phytoplankton diatoms and picoplankton were more effective at PF.

The Cost of Fishing on Juveniles of Finfish and Shellfish: Assessment of Economic Impacts of Trawl Juvenile by-Catch along the Coast of North Andhra Pradesh, India

Abstract: A study was carried out to assess the economic value of juveniles of commercially important species of finfish and shellfish caught as by-catch by multiday commercial trawlers operated off the coast of Visakhapatnam, north Andhra Pradesh from January 2014 to December 2015. Juveniles of twenty species (four species of cephalopods and sixteen species of finfish) were found to dominate the trawl by-catch. The landed juveniles of these 20 species formed 12,757.16 t and 286.86 million numbers per year and their contribution to the total landings of these species in trawl by-catch were 55.30% by weight and 57.03% by numbers. The highest percentage of quantities of juveniles (biomass) was found in trawl by-catch in the months of August and July in, 2014 and 2015 respectively. Among the juveniles, ribbonfish (Trichiurus lepturus) and goatfish (Upeneus vittatus) dominated, contributing together, on an average 11.60% by weight and 33.68% by numbers respectively. Using the bio-economic model, it was estimated that if the juveniles were allowed to grow up to length at first maturity; total annual economic gain would have been Rs. 273.21 crores (42.03 million USD) with biomass gain of 44,493.02 t per annum. The estimated total annual biomass would have increased 3.46 times with an increase in revenue by 4.20 times. Annual average loss due to fishing of juveniles was estimated to be Rs. 209.62 crores (32.25 million USD). The results of the present study suggested that sustainable harvest of these resources would have yielded maximum economic return to the fishers. With the help of stakeholders using a participatory approach, management measures such as increase of cod end mesh size of trawl to 40 mm from the present mesh size of 10–12 mm, use of square mesh for trawl cod ends, fishing effort restriction and awareness campaign on the detrimental impacts of catching juveniles needs to be implemented at the earliest for avoiding growth overfishing.

Documentation of Istiblennius dussumieri (Blenniiformes: Blenniidae) from the Northern Bay of Bengal, with Ecological Notes

Abstract: This study presents the first detailed description of a blenniid fish, Istiblennius dussumieri (Valenciennes 1836) from Bangladesh, representing the northernmost limit of its distribution in the Bay of Bengal. Based on nine specimens collected from the rocky tidepool habitat, diagnostic accounts of I. dussumieri are provided with photographs showing sensory pores and cirri, which are rarely illustrated in the literature.

Influence of Thermodynamic Indices During Severe Convection over Andaman Nicobar and Lakshadweep Islands

Abstract: The current work is an attempt to study various parameters that influence the occurrence of severe convective activity over two regions, Andaman and Nicobar islands (AND) and Lakshadweep (LAK). k index (KI), total totals index (TTI), Modified K-index (MODKI), Modified total totals index (MODTTI), total precipitable water (TPW), humidity index (HI), deep convective index (DCI), lifted index (LI), convective available potential energy (CAPE) and convective inhibition (CIN) are the parameters used in this analysis. ECMWF Reanalysis 5th Generation (ERA5) and Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA2) reanalysis daily datasets were utilized to study the severe convective activities during 2019. The modified indices of KI and TTI parameters clearly indicated the good chances for occurrence of severe convective systems in monsoon season. The spatial distributions clearly indicated the strong impact of south westerly winds on these islands which lead to the occurrences of high rainfall activity on these islands. The westerly wind values (7 to 9 m/s) are higher over LAK region than AND region (4 to 8 m/s). High sea level pressure (SLP) values help the intensification of south-westerly winds that lead to severe rainfall over islands. The sea surface temperature (SST) values 30 to 30.5 °C were observed over AND and LAK regions. AND region received good rainfall in winter and monsoon season, whereas LAK region receives higher rainfall in monsoon and post-monsoon season. We may infer from this analysis that LAK region has more convection occurrences than AND region. The WRF model prediction was found to be accurate with ERA5 reanalysis data. The WRF model was useful in predicting the severe convective activities prior to their occurrence.

Evaluating the Fish Community of “Los Petenes” Biosphere Reserve, Campeche, Mexico, through the Characteristics of the Environment and Indicators of Taxonomic Diversity

Abstract: The coastal zone of Los Petenes” Biosphere Reserve, is a critical breeding habitat for many species, particularly fish. Despite its low anthropic impact, development on the coastal area around the reserve is gradually increasing and fishing activities continue to grow; however, there are few studies on fish communities and the characteristics of their environment. In addition, there are no reference indexes to measure possible future impacts on the fish community. In order to obtain a baseline index, we carried out 12 monthly campaigns at 24 sampling sites between May 2013 and April 2014 in the coastal area of the reserve. Through these months we analysed water environmental variables, and calculated various diversity indexes: species richness (S), evenness (E1/D), importance index (IV), and indexes of taxonomic distinctiveness (Δ*, Δ+, Ʌ+). There are significant environment variations through these months, but there is no evident variation between sampling sites. We identify 45 species of fish grouped into 44 genera, 20 families, 15 suborders, 13 orders, 2 subclasses and 2 classes. According to index IV (> 10), 12 species are important. Taxonomic diversity indexes are sensitive to environmental variation, mainly during the rainy season. We establish the preferred environmental characteristics of all 45 species. This study allows for the establishment of baseline index values for the state of the Reserve that can be reassessed in future research regarding the impact of developing fishing, tourism and urban activities in the region.