Thalassas: An International Journal of Marine Sciences最新文献

Both macroscopic vertebrates and invertebrates associated with jellyfishes in Sri Lankan waters were surveyed in 2017, as their interactions had not been studied before. In the survey, young teleost fishes were observed to be swimming together with medusae of Phyllorhiza punctata, and the absence of mesoglea in the stomach contents of the teleost Carangoides praeustus confirmed that the association is not a predatory relationship, but could be commensalism. Similar swimming behaviour was observed in the teleost Gnathanodon speciosus with the medusa, Acromitus flagellatus using underwater footage. Further, an association of the brittle star Ophiocnemis marmorata with jellyfishes, Marivagia stellata and Mastigias sidereus, was also reported in this study from Sri Lankan waters, and this relationship could be kleptoparasitism. Likewise, an assemblage of a copepod, Paramacrochiron sp., with medusae of Lobonemoides gracilis and Rhopilema hispidum was known as parasitism. This study reports, for the first time, the associations of C. praeustus,–P. punctata, G. speciosus,–A. flagellatus, O. marmorata,–M. stellata, O. marmorata,– and M. sidereus.

This paper analyzes the interacting good bio-mass and bird population for the wetland system of Keoladeo National Park (KNP). The system dynamics is analyzed with and without time delay. The bifurcating periodic solution properties are investigated by normal form and central manifold arguments. The computer simulation is performed to validate the analytical findings that show the different dynamical outcomes such as stable and oscillatory dynamics in the absence of time delay. The numerical computation is performed for the delayed system and the stability behavior of gestation delay for different cases is investigated. The system dynamics show the chaotic behavior when the two crucial parameters (carrying capacity of good biomass and intensity of interference of bird population) have a high time delay value. Further, the diffusion-induced instability conditions are derived. The obtained spatial patterns show that the time and intensity of interference can change the spatial distributions, and the hot and cold spots pattern appears in the whole domain.

In the present article, the authors report on the first record of Ophisurus serpens (Linnaeus, 1758) from the Sea of Marmara (GFCM geographical subarea 28). A sexually mature male specimen (TL 1841 mm and TW 1801 g) was captured in a gill-net fishery at 96 m depth off the Silivri coast (northern Sea of Marmara, Türkiye).

The commercial interest in Ulva has emanated due to its emerging applications in functional foods, bioactive ingredients, salt and polysaccharide ulvan. The growth is important trait for aquaculture and conventionally measured in terms of difference in weight in geometric progression. Cell division is fundamental, and cell bio-volume is precise, non-cumbersome and cost-effective method for determining growth, but seldom attempted in seaweeds. The percentage of divided cells ranged from 59.8 ± 8.9 to 60.4 ± 3.4 % and un-divided cells from 40.1 ± 9 to 40.8 ± 3.4 %. The bio-volume of un-divided cells ranged from 4896.1 ± 393.9 µm² to 6965.2 ± 1806.09 µm²; while divided ranged from 3504.2 ± 470.03 µm² to 4952.3 ± 759.2 µm²; it was statistically different in day 0, day 3 and day 6.

Abstract

This study deals with the taxonomy and environmental implications of recent benthic foraminifers from the coast on the Susa area in northeast Libya. Six recent sediment samples were collected from the beach of the Susa area at a depth of less than 1 m. Twenty grams of each sample were weighed and processed with standard methods to extract the foraminifera. Thirty-nine species of benthic foraminifera belonging to twenty genera under the Textularina, Rotalina, Spirillinina, and Miliolina suborders were identified and systematically described. The most common genera are Amphiseigina and Textularia, which form 49.7% and 20.25% of the recorded fauna, respectively. Followed by Peneroplis (i.e., symbiont-bearing taxa) (11.6%), Quinqueloculina (4.2%), Elphidium (3.1%), Sorites (2.5%), Adelosina (1.3%), Spiroloculina (1%), and Rosalina (0.9%). Amphistegina lessonii is the most dominant species (49.7%) of the total assemblage. Textularia bocki and Peneroplis pertusus are also dominant species (13.8% and 7.8%, respectively). Environmentally, the analysis of benthic foraminifers in this study shows the effect of pollution and abnormal environmental conditions. Various diversity indices, including species richness (S), the Shannon index, the Simpson index, the Fisher alpha index, and dominance, have been investigated, and foraminiferal test abnormalities as well. The foraminifera display very low to moderate density and low diversity and frequent occurrence of abnormal specimens have been recorded. Eleven test abnormalities are described and illustrated, including (1) double apertures, (2) reduction in the size of the chambers, (3) extra chambers, (4) complex forms, (5) enlarged and deformed apertures, (6) aberrant chamber shapes, (7) twinned forms, (8) loose milliolid coiling (9) wrong coiling, (10) twisted tests and (11) corroded tests. The ecological quality status EcoQS has been evaluated for the studied stations using the Shannon-Wiener H’ (log2) indices, where station 3 has a poor EcoQS, stations 1, 2, 4, and 6 have a moderate EcoQS, and station 5 has a good EcoQS. Three types of pollutants are recognized in the study area, which are sewage, desalination plants wastewater discharge and patches of oil accumulation along the beach. The present findings are essential for enhancing Susa coast habitat conservation and management in the coming years.

Abstract

The bacteria associated with marine invertebrates are considered as a potential source of biologically active compounds. In the present study, the bacterium Vibrio alginolyticus obtained from the shell surface of the marine gastropod Turbo intercostalis displayed strong antibacterial activity in the preliminary screening against biofilm-forming bacteria. Further antibiofilm assay exhibited that the extract of V. alginolyticus substantially inhibited the biofilm forming ability of Alteromonas sp. Moreover, the extract of V. alginolyticus showed significant antifouling activity against the marine biofouling organisms in the field study conducted in the coastal waters. In addition, the active components of the extract were eluted by chromatography methods and analysed using gas chromatography and mass spectroscopy (GC-MS). The obtained GC-MS spectrum indicated the presence of the compounds such as 1H-Indole, 5-methyl-2-phenyl, 2-Ethylacridine and diethyl bis (trimethylsilyl) silicate. The in silico analysis of the identified compounds was carried out against the molecular target barnacle cement protein. The compound 2-Ethylacridine showed promising activity than the other compounds including the reference antifouling agent 5-Dichloro-2-n-octyl-4-isothiazolin-3-one. In conclusion, results of this study indicated the antibiofilm and antifouling activities of the compounds produced by the bacterium V. alginolyticus. These compounds could serve as potential leads for the development of natural product-based antifouling agents.

Here, we studied the chemical composition of Spheciospongia aff. Mastoidea sponge collected from the Red Sea. The chemical profile of the n-hexane fraction was studied using GC-MS and revealed the presence of 11 compounds. The most abundant compounds were hexadecanoic acid methyl ester (49.93%), 9-octadecenoic acid methyl ester (22.13%), and other minor products. Additionally, three compounds were isolated from the ethyl acetate and n-butanol fractions of Spheciospongia aff. Mastoidea and identified as β-sitosterol, cholesterol, and allantoin, respectively. The chemical structures of the isolated compounds were identified by different spectroscopic methods, including mass and NMR spectroscopy. Crude polysaccharides (CPs) were also extracted from the aqueous extract of the collected sponge, and HPLC-RID characterized their monosaccharides. We developed a biological method for synthesizing silver nanoparticles using the reducing power of CPs. The biosynthesized AgNPs were confirmed using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Zeta potential. The nanoparticles had a spherical shape in the TEM image, with an average size of 18.21 to 36.92 nm and zeta potential values of -27.3 mV. The biosynthesized AgNPs-CPs showed enhanced antibacterial activity against several pathogens compared to CPs with no remarkable activity. Moreover, the AgNPs-CPs exhibited a cytotoxic effect against breast adenocarcinoma cell lines (MCF-7), liver cancer cell lines (HepG-2), prostate cancer cell lines (PC-3), adenocarcinomas alveolar basal epithelial cells (A549), and colorectal carcinoma cell lines (HCT116) with IC₅₀ values of 5.60, 13.0, 2.62, 46.3, and 29.20 µg/ml, respectively.

Here, we describe the morphology of the setal types of the feeding apparatus (mandible, maxillule, maxilla, first to third maxillipeds and the cheliped) of three species of sesarmid crabs, Aratus pisonii, Armases angustipes and Sesarma rectum, using scanning electron microscopy (SEM) techniques. The setal types previously identified encompass pappose, plumose, plumodenticulate, serrated, simple, and cuspidate, each with its own distinct subtypes. Three different types of setae are described and named here: capitate, cluster serrated, and scopa setae. The three species’ mouthparts are very similar, but Aratus pisonii has some marked differences, being the only species to have capitate setae on the first maxilliped, base and coxa of the maxilla and maxillule, and mandibular palp, plumodenticulate setae in the mandibular palp and tufts of cluster serrated setae in the chelipeds. Because it is considered the most herbivorous species among those studied, such differences possibly relate to the feeding habits.

The shape of otoliths of three species of fishes of the genus Pagellus (Pagellus erythrinus, Pagellus acarne and Pagellus bogaraveo) sampled in the marine environment of the western Mediterranean (Kelibia Sea) and the eastern Mediterranean (Bizerte Sea) in Tunisia was studied in order to determine a differentiation by a discriminant factorial analysis and an analysis of biometric measurements. The different results showed an asymmetry within and between the otoliths of the different populations. Despite the difference between Pagellus erythrinus of the Western basin and Pagellus erythrinus of the Eastern basin, the variation observed within each species fades before the total variation of the species studied The Pagellus erythrinus sampled in the basin (Western and Eastern) allowed us to highlight the polymorphism of the otoliths thanks to the highly significant differences obtained (p-value < 0.0001).

Chitons are one of the least studied marine invertebrates from the Indian Ocean. Acanthopleura vaillantii is a rocky intertidal chiton species restricted to the north-western Indian Ocean, specifically along the coasts of the Red Sea, Gulf of Aden, and Gulf of Oman. In this study, we sequenced the complete mitochondrial genome of A. vaillantii for the first time. The length of the genome was found to be 15,271 bp, containing 13 PCGs, two rRNA, and 22 tRNA. Phylogenetic analysis of A. vaillantii using maximum likelihood and Bayesian inference methods, based on all 13 PCGs supports the recent classification of chitons and places A. vaillantii within the clade representing subfamily Acanthopleurinae. This study presents the first complete mitochondrial genome of a chiton species from the Indian Ocean.