Thalassas: An International Journal of Marine Sciences最新文献

In this study, agarophyte Gracilaria edulis was successfully cultivated in laboratory condition. An attempt to grow G. edulis by removing associated bacteria was made to identify their role in the host growth. But antibiotic treatment did not remove the associated bacteria completely rather reduced the bacterial load. Antibiotic untreated (ABUT) sample grew well in the beginning of culture but degraded gradually in prolonged cultivation. This ascertained by the dominance of surface-associated harmful bacteria. The antibiotic treatment for 48 h (ABT-T48) showed the best growth but antibiotic treatment for 48 h weekly once for 4 weeks (ABT-W48) resulted comparatively less growth. The metagenomic analysis revealed variation in the bacterial diversity and population between the samples of ABUT and ABT-W48. The ABUT sample possessed abundant agar-degrading and algae-lytic bacteria. In contrast, numerous beneficial bacteria like Lactobacillus, Prevotella, Clostridium and Swaminathania are dominant in ABT-W48 sample. It was observed that weekly antibiotic treatment inhibited some beneficial bacteria like Acetobacter. This show necessity of moderate antibiotic treatments to reduce harmful bacteria and encourage beneficial bacteria association. Removing the harmful bacteria promote the alga growth by keeping a balance in bacterial diversity (normobiosis) within the host. Six culturable bacteria associated with G. edulis isolated and identified are Vibrio brasiliensis, two strains of Paracoccus zeaxanthinifaciens, Alteromonas sp., Pseudoalteromonas sp.(a putative novel), and Bacillus licheniformis.

Abstract

Blood Cockle (A. nodifera) have great potential for development, especially in the health sector. One of its essential components are fatty acids, which show potential as antihypertensive agents. This study aims to evaluate the potential of fatty acids in Blood Cockle (A. nodifera) as antihypertensive drugs through an in-silico approach using molecular docking method. The stages of this research include extraction, GC–MS analysis, molecular docking analysis, and ADME analysis. The study used angiotensin converting enzyme (ACE) as the target protein and ligand compounds derived from fatty acid isolates and the control drug captopril for comparison. The initial stage includes protein and ligand preparation, molecular docking and visualization. The potential compounds are then evaluated with Lipinski’s rule. The results showed that 5,8,11,14,17-Eicosapentaenoic acid have potential as ACE inhibitors, thus showing potential as antihypertensive drugs. More research is needed, including in vitro and in vivo testing, to optimize the medical potential of Blood Cockle (A. nodifera).

An extensive parasitic survey on the Black Pomfret Parastromateus niger (Bloch) (Carangidae) was carried out along the coastal waters of India. A total of 162 host fish (P. niger) were collected, in which 72.2% of the fish were infested with parasitic crustaceans. Six species of parasitic crustaceans were collected, including one species of cymothoid isopod Cymothoa eremita (Brünnich, 1783), and five species of copepods belonging to five different families such as Bomolochus megaceros Heller, 1865 (Bomolochidae), Lernaeenicus stromatei Gnanamuthu, 1953 (Pennellidae), Lernanthropus koenigii Steenstrup and Lütken, 1861 (Lernanthropidae), Synestius caliginus Steenstrup and Lütken, 1861 (Caligidae) and Thysanote appendiculata. (Steenstrup and Lütken, 1861) (Lernaeopodidae). Even though six species of parasitic crustaceans were recovered from the host fish, simultaneous multiple parasitism seldom occurred (only 10%). The prevalence, mean intensity, and mean abundance of each parasite were calculated. The taxonomic account, host, site, and niche-specific parasitization of each species, are discussed. The present study also reviewed and discussed the simultaneous multiple co-occurrence of parasitic crustaceans.

A single specimen of Uraspis uraspis was collected in the gillnet landings from the coast of Andaman and Nicobar Islands. The present study reports the first geographical record and redescription of Uraspis uraspis from this region. The specimen was identified morphologically and reconfirmed through molecular barcoding. DNA was extracted from the specimen, and the partial region of the cox1 gene was amplified and sequenced. The obtained partial sequence was edited to remove ambiguous nucleotides resulting in a 625 bp long sequence. The sequence was then submitted to the NCBI’s GenBank database (GenBank accession number MZ766929.1). The main distinguishing characteristics of U. uraspis were white tongue, white palate membrane, and naked breast area. Phylogenetic reconstruction of 604 base paired aligned sequence was compared with barcodes of 93 sequences of similar and different species. Upon construction of the maximum likelihood, Neighbor-joining and MrBayes tree, Andaman isolate of Uraspis uraspis species was found to be forming a distinct clade with other species of Uraspis with high statistical support. Analysis of intraspecific and interspecific genetic distance also showed the similarity between Andaman isolate and U. uraspis from other regions (intraspecific genetic distance < 0.01) and the difference between different species of the same genus (interspecific genetic distance > 0.02). Genetic distance values between and within species also supported the distinct clade formation of Uraspis sp. in the phylogenetic trees.

Abstract

This study focused on identifying and estimating the number of rays and sharks caught incidentally in the Moroccan Mediterranean Sea and their seasonal variation. In 2020, from 62 bottom trawl surveys, it was estimated that elasmobranchs represent 6.67% (25 kg) of the total catch (372 kg/trip) per trip in Al Hoceima Bay. Raja clavata and Scyliorhinus canicula were the most abundant species, representing between 27% and 21% of the total elasmobranchs captured, respectively, followed by Prionace glauca (19%) and Oxynotus centrina (13%). Single or sporadic captures of the threatened and protected Isurus oxyrinchus and Mobula mobular were further recorded, as well as of the endemic and threatened Raja radula. Elasmobranch bycatch rates vary with depth, season and fishing area. The current data indicate that the Moroccan Mediterranean may be an important breeding area for many elasmobranchs. They also emphasize the urgent necessity of better understanding the interactions between fisheries and elasmobranchs to develop management measures.

Despite not being included in Türkiye's official fisheries statistics, dolphinfish have been actively targeted by anglers and spearfishers, as evidenced by citizen science data reviewed in this study. Given the absence of commercial fishing and organized sport fishery, social media records were assessed to gauge the fishing activity around this species. The upload pattern of Youtube fishing videos revealed a seasonal trend, peaking in October. Notably, offshore anglers' videos received significantly more views and likes compared to those from inshore anglers and spearfishers. This study also provides the length distribution, sex ratio and length–weight relationship of dolphinfish in Türkiye's waters of Levant Sea for the first time. The maximum length closely corresponds to results found in other studies conducted within the eastern Mediterranean region.

This preliminary study investigated the diet composition and diet overlap for both Sardina pilchardus and Sardinella aurita, as well as the zooplankton distribution (with a special focus on copepods) in the representative region of Algiers coast (Bou Ismail Bay) during a short period on June 2015. This month can be considered representative of the summer (and autumn) season (s), since between the two periods, the meteorological characteristics remain homogeneous. The study area, is considered one of the most prestigious bays on the Algerian coast, regarding fisheries production. At the level of the food web, trophic interactions link predators (fish populations) to zooplankton prey. At Bouharoun port, also located in the bay of Bous Ismail, samples were obtained from commercial fisheries of S. pilchardus and S. aurita. Additionally, zooplankton samples were collected vertically in the 0-100 m layer. Based on stomach content analysis, significant diet overlap was observed between S. pilchardus and S. aurita (Schoener index : D = 0.76) indicating similar feeding habits (Morisita-Horn index: O = 0.94). Copepods were preferential prey for both fish species with high frequencies (F _Saurita = 91.66%, F_S.pilchardus = 85%). Their highest average number found in the diet of S. aurita was represented by Centropages typicus, followed by Centropages chierachiae and Temora stylifera; while Nannocalanus minor was mainly consumed species by S. pilchardus. Copepod populations were dominant in S. pilchardus and S. aurita feeding strategies. A total of 22 copepod species were identified in the water column, mostly in the Calanidae. Their distribution varied significantly across stations (p = 0.046); three species (T. stylifera, C. typicus and C. violaceus) contributed mostly to this variation. Copepods have a relationship with environmental parameters (e.g., temperature, chlorophyll a, and NO₃).

The present study analyzed the genetic and morphological variability in Eurytium limosum in different marine provinces of the Western Atlantic. An integrative approach using genetic and morphological data was applied to test the influence of such provinces as possible barriers on the gene flow of the species. Two mtDNA markers were used to construct the genetic distance matrices, phylogenetic trees, and haplotype networks. Meanwhile, the morphological analysis of a robust set of specimens provided a detailed report on all diagnostic characteristics in the literature. Both approaches revealed great similarity between specimens from different localities and provinces, in addition to the absence of genetic structuring throughout their wide area of occurrence. The relationship between dispersal and larval development patterns was selected as the main factor promoting the population profile. This approach provides some elements that serve as a baseline for future studies on decision-making regarding the conservation of intertidal communities.

The present study provided the first knowledge on a broad-scale biometric distribution of the seagrass meadow (Posidonia oceanica) throughout the entire Turkish Mediterranean Sea coast. In this study, two surveys were conducted in winter and summer season of 2019, covering bottom depths range of 5–35 m to assess the growth dynamics and distribution of the P. oceanica. P. oceanica samples were collected from each sampling site by a SCUBA diver with quadrat sampling method for biometrics data. The physicochemical properties and optic characteristics of the water were also determined. Season, site, bottom type, and depth appeared to be determinative on biometric characteristics and distribution of P. oceanica. About one-third of the bottom surface area of the Turkish Mediterranean Sea coast was covered by the P. oceanica. The shoot density did not change seasonally. Leaf biomass and leaf area index were two times higher in summer compared to winter. The biometric characteristics of P. oceanica and distribution pattern differed based on the bottom type of the region. The bottom of Muğla bay is composed of sand and mud, Antalya Bay is mainly composed of rock, and Mersin Bay is mainly composed of matte and mud. Sampling season and region appeared to be determinative on biometric characters (leaf length and width, rhizome length and width or diameter, sheath length and width). The size of the meadows showed a decreasing trend with increasing depth. High variation in morphologic characters was observed in P. oceanica distributed around 15–20 m depth compared to those distributed in shallower or deeper zones. The main seasonal differences were observed in rhizome-related and leaf-related biometrics. Ecological analyses revealed that the biometric characteristics of P. oceanica were affected by season (based on changes in salinity and temperature), region (depending on bottom type), and distribution depth. In winter, the meadow was interacted with salinity, temperature and oxygen of the water. Nitrogen based-nutrients were related to the seasonal growth dynamics of the P. oceanica. The optical parameters (Sechhi depth and percent PAR, Photosynthetically Active Radiation) were not correlated with the biometrics, but the P. oceanica was found in a range of 10% to 30% of PAR. Overall, the density variables were contrasted to the morphometrical variables during the growth dynamics of the meadow. This study has presented SCUBA biometrical data which were used for in situ calibration with the corresponding acoustical echo energy of the seagrass and was an approach to use non-destructive method, the acoustical techniques.

Abstract

Beta-glucan is a natural polysaccharide, abundantly present in the cell walls of several fungi, majorly in mushrooms, yeasts and many bacterial species. It can be used in the cosmetics industry as it has good anti-aging, wound healing and antioxidant properties. Marine yeasts were isolated from the backwater samples derived from Andaman-Nicobar Islands, India and screened for beta-glucan production. Among 38 yeast isolates, 5 isolates could produce beta-glucan and they were further chosen for UV mutagenesis at different time intervals for strain improvement. Mutated marine yeast isolate DAMB1 was found to be producing the highest amount of beta-glucan (1.67 gm/100 ml). Further, potential isolates were characterized microscopically and checked for their antioxidant activity and anti-bacterial activity against bacterial pathogens. The beta-glucan compounds exhibited good antioxidant activity as well as good antimicrobial activity against all the pathogens and highest against Staphylococcus aureus (23 ± 0.7 mm). The yeast-derived compound was structurally characterized using GCMS analysis and represented the presence of Ethylthiophosphonamide Acid, O-methyl Ester, and 1,2,4-Trithiolane which are highly pure fatty acid methyl esters. The extracted beta-glucan compound from potential yeast isolate was used to formulate beta-glucan almond scrub consisting of sweet almond oil and almond powder. The beta-glucan almond scrub showed no side effects or infection on the skin after a period of usage (10 weeks) rather it smoothened out the rough skin to an extent. Finally, the yeast was further characterized and identified as Rhodotorula sp. DAMB1 (Acc. No. MK968443) through 18s rRNA sequencing analysis.