Thalassas: An International Journal of Marine Sciences最新文献

In this study, we revealed ontogenetic development, length–weight relationship, otolith size relationships, otolith shape analyses, spatial distribution of mean abundance and feeding of Shi drum, Umbrina cirrosa juveniles in the Marmara Sea, Türkiye. The individuals ranged in total length (TL) between 49.44 mm and 128.46 mm, with a mean of 98.43 ± 5.43 mm; and the specimens were distributed in weight from 1.15 g to 21.51 g, with a mean of 9.63 ± 1.23 g. The total length–weight relationship was calculated as W = 0.000008xTL^3.0163 and an isometric growth was detected. U. cirrosa had relatively large sagittal otoliths, and the otolith size – fish size relationships were detected as linear. The otolith shape analyses showed that the juvenile sagitta shape indices are relatively the same as the adults. Stomach content of juvenile Shi drum contained mostly Amphipoda. The biological data on the early life stages of Shi drum is scarce, and the outputs of the presented data reveal first detailed results.

Abstract

Fish fecundity is a key life history characteristic, and can be used in stock assessment and management. In this study, we estimated the batch fecundity of the Atlantic chub mackerel Scomber colias, along the coast of Morocco at two locations: Larache in eastern Atlantic and M’diq in western Mediterranean. The sampling program of the studied specimens was carried out by the purse seine fleet during the spawning season. The individual egg production was similar between locations, with no significant differences, resulting in a mean batch fecundity of 54,389 ± 18,763 eggs, and a relative batch fecundity of 269 ± 51.9 eggs/g. We analyzed the effect of internal drives like size (total length and total weight) and age, but also the fish condition. Size and age were good predictors of fecundity with models incorporating age explaining the highest proportion of variance. The condition factor was positively related with the batch fecundity, females with better condition spawn a large amount of eggs. The refinement of the estimates of egg production of Scomber colias might represent a step forward to improve the assessment of this species in Moroccan waters.

Abstract

The paper mentioned was applied using the fish samples obtained by commercial fishermen using gillnets through the stationary set and drive in fishing methods in order to search out length-girth relationships (LGRs) of blotched picarel (Spicara maena (Linnaeus, 1758)), picarel (Spicara smaris (Linnaeus, 1758)) and mediterranean rainbow wrasse (Coris julis (Linnaeus, 1758)) between January 2021 and December 2021 in the Saros Bay (northern Aegean Sea, Türkiye). The opercular girth-length relationships were calculated as G_ope = 0.7176TL – 3.4105 (r² = 0.89), G_ope = 0.5579TL – 2.4407 (r² = 0.89) and G_ope = 0.9118TL – 7.3585 (r² = 0.93), whilst the maximum girth-length relationships were estimated as G_max = 0.9124TL – 4.7124 (r² = 0.82), G_max = 0.5874TL – 1.2491 (r² = 0.80) and G_max = 1.0227TL – 8.6218 (r² = 0.95) for Spicara maena, Spicara smaris and Coris julis, respectively. All linear regressions of this research were statistically notable (p < 0.001). The existing research involves the first findings of LGRs of Spicara smaris for the North Aegean Sea, whilst any LGRs values of Coris julis have in days of yore been not reported worldwide, but the paper mentioned. Since the relevant valuates are remarkable for development the selectivity of fishing equipments in order to forestall the seize of immature, undersized, younger fish, it will bolster the advancement of the ecosystem-based fisheries management.

Benthic macrofauna differs in sensitivity, tolerance, and adaptability to environmental fluctuations and disturbances induced by various anthropogenic activities. These activities pose an environmental threat to aquatic biota; thus, benthic macroinvertebrates are utilized as bioindicators of stressors. This study aimed to assess the ecological quality status (EcoQs) of Nigeria's offshore waters using macrobenthic diversity and ecological biotic indices. Bottom sediments were collected from seven (7) stations using Van-Veen grab, and Niskin water sampler for surface water onboard the RV-BAYAGBONA. The identified macrofauna communities were subjected to AZTI’s Marine Biotic Index (AMBI) to depict the ecological quality status of the environment. The physico-chemical parameters (Water temperature, dissolved oxygen, conductivity, depth, pH, alkalinity, salinity, phosphate, and nitrate) using a multi-parameter checker, HORIBA-U53. The physico-chemical parameters of the bottom water showed significant differences (p < 0.05) in DO (ST 1 – 3.9*, ST 2 – 6.31* mg/L) and pH (ST 1 – 7.9*, ST 7 – 8.02*), while the surface water showed significant differences (p < 0.05) across all stations. A total of 45 species belonging to 6 classes and 4 phyla were identified in the bottom sediments in the order Mollusca (90.98%) > Annelida (6.67%) > Sipuncula (1.57%) > Porifera (0.78%). The macrofauna community was mostly dominated by Gastropoda (ecological groupings of I and II) and Polychaete (ecological group of III). The biotic indices were ecologically grouped into I (54.3%) and II (42.5%) species that are sensitive and indifferent to pollution and group III (3.2%) tolerant species to excessive organic pollution. The biotic indices were assessed based on the level of sensitivity of the benthic community in response to anthropogenic stressors. Thus, the ecological status using AMBI, M-AMBI, and BI indicated an undisturbed marine environment (healthy EcoQs) with less anthropogenic impacts. Although periodic biomonitoring of the coastal waters is recommended, this is due to the installation of crude oil platforms for exploitation, and fishery activities deploying bottom trawling. Furthermore, complementary use of diverse indices relating to sensitivity/tolerance-based indices is highly recommended to establish a robust database on ecological grouping for diverse benthic species within the western Atlantic Ocean.

Graphical Abstract

Abstract

A mineralogical survey was conducted in the Gulf of Guinea beach sediments to assess the transport history, depositional environment, weathering conditions, and provenance. Heavy mineral assemblages are abundant in augite, followed by opaque minerals, diopside, zoisite, enstatite, tourmaline, zircon, rutile, sillimanite, garnet, apatite, hornblende, epidote, kyanite, chloritoid, and staurolite. The variety of this minerals shows that the sands studied come from the igneous source rocks, mainly from a metamorphic source, in particular the gneisses and basalts, which is consistent with the geology of the study area. The bulk mineralogy detected using XRD and the chemical properties obtained by SEM–EDS reveals that the sands were dominated by quartz. Nineteen microtextures were observed on heavy minerals like hornblende, chloritoid, sillimanite, garnet, augite and staurolite, which were subsequently classified as mechanical (13 features), chemical (4 features), and combined mechanical and chemical (2 features) origins. The dominance of mechanical features suggests that the grains underwent high-energy transport. The abundance of angular and subangular heavy minerals indicate a nearby source. The mineral composition suggests that the source rocks underwent a moderate weathering. The sub-rounded and rounded heavy minerals indicate a long transport. The predominance of heavy minerals in sediments suggests that the nearby source rocks are rich in heavy minerals.

Present study was aimed to study the ecology of intertidal Asteroidea from the rocky shores of Gujarat state of India. For this study, eight rocky shores viz., Okha, Shivrajpur, Dwarka, Mangrol, Veraval, Dhamlej, Simbor and Diu of the Gujarat coastline were selected and surveyed extensively from January to December 2021. Though the shores studied are situated along a continuous coastline, significant spatiotemporal variations in their diversity, distribution and density were observed. Four intertidal Asteroidea Echinaster purpureus, Anthenea rudis, Aqulionastra lorioli and Aqulionastra burtoni were identified and studied. The present study revealed that species diversity and density of Asteroidea were varied over temporal and diverse spatial scales. The distribution pattern of different asteroid species was also found to be varied in the rocky shores studied. It is possible that along with the prevailing climatic conditions of the study period and the intertidal faunal composition therein, coastal structure and various microhabitats might have played a vital role in the observed differences. Empirical data provided in this study offers a better understanding of intertidal Asteroidea and provides the baseline for future field and experimental studies on predation, interspecific and intraspecific competition and coexistence in intertidal communities.

The plain helmet gurnard fish Dactyloptena tiltoni Eschmeyer (1997) is reported for the first time from the Arabian Sea based on a single female specimen measuring 295 mm standard length. The specimen was collected from bycatch landings in a multi-day shrimp trawl fishery at a depth ranging between 300 and 400 m from Sakthikulangara fishing harbour, Kerala. This species has previously been reported from the Pacific Ocean. The specimen is described, and the new distributional record from the northern Indian Ocean is confirmed. Morphometric and meristic characters, along with previous distributional records from the world ocean, are also provided.

Abstract

In India, report of the naticid gastropod Sinum laevigatum has been rare, with little description of the species. However, a benthic investigation (November 2022) undertaken in the Dhamra estuary and the adjacent waters, Odisha, on the east coast of peninsular India, revealed the occurrence of the species for the first time. Here we present the morphometrics, description, and baseline ecological data of the specimens of S. laevigatum hitherto unknown from mainland India. Furthermore, its current prevalence along the mainland’s coastal waters indicates a range extension northwestward from the Andaman and Nicobar Islands in the Bay of Bengal, where the naticid was previously documented (2003). It is contended that the information provided could address knowledge gaps for the species.

The current study focuses on seasonal variations in coastal water along the Bhavnagar coast, Gulf of Khambhat, Gujarat, India, during three consecutive seasons (pre–monsoon, monsoon, and post–monsoon). The coastal water samples were collected from seven different locations (Ghogha, Kuda, Mithivirdi, Sosiya, Alang, Sartanpar, and Gopnath). In the designated research region, coastal water samples were collected and evaluated for water physico–chemical characteristics and heavy metals. As a result, sea surface temperature, pH, conductivity, total dissolved solids (TDS), total suspended solids (TSS), total hardness (TH), calcium hardness (Ca⁺²), chloride (Cl⁻), salinity, dissolved oxygen (DO), 5th –day biochemical oxygen demand (BOD), chemical oxygen demand (COD) and distribution of dissolved heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were investigated at Bhavnagar coast, Gulf of Khambhat. The multivariate statistical analysis indicates that temperature, DO, BOD, COD, Cr, Co, Mn, and Fe, the natural and anthropogenic condition affects the water parameter and dissolved heavy metal. The outcome revealed a dilution effect in physico–chemical parameters and dissolved heavy metal during the monsoon season. The results indicate that anthropogenic disturbances and the growth of a range of activities with increasing point and non–point rainfall poured directly into coastal regions affect coastal water. As a result, the current study’s findings may be useful to government authorities trying to safeguard the long–term sustainability of the Gulf of Khambhat.

The aim of this study is to evaluate the effects of potassium diformate (KDF) and butyric acid (BA), both separately and in combination, on the growth performance, biochemical parameters, innate immune system, and digestive enzyme activity of Beluga (Huso huso). Fish (average weight of 28.39 ± 1.82 g) were divided into seven groups, each receiving a different diet: control, 2 g/kg^− 1 KDF, 5 g/kg^− 1 KDF, 10 g/kg^− 1 KDF, 2 g/kg^− 1 BA, 5 g/kg^− 1 BA, 10 g/kg^− 1 BA, and 5 g/kg^− 1 KDF + 5 g/kg^− 1 BA. The fish were fed twice daily at a rate of 2% of their biomass and water parameters were monitored throughout the experiment. At the end of the experiment, 45 fish (6 from each treatment diet) were euthanized, and their weight and blood samples were collected for analysis. The study revealed improved growth performance parameters in Beluga fish fed diets containing KDF and BA, either separately or together. However, there was a significant decrease in Specific Growth Rate (SGR) compared to the control group (P < 0.05).The KDF and BA supplements significantly reduced levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) enzymes, and increased serum total protein, globulin, albumin, lysozyme enzyme activity, and alternative complement pathway activity. Incorporating KDF and BA supplements also led to a notable increase in digestive enzyme activities (protease, trypsin, chymotrypsin, lipase, and alpha amylase), with the highest levels seen in the KDF 10 and KDF + BA groups (P < 0.05). These findings suggest that diets containing KDF and a combination of KDF and BA have a beneficial effect on the growth, metabolism, and immunity of Beluga fish. The study suggests that the incorporation of a combination of KDF and BA into the diet of Beluga fish can result in improved growth and enhanced immune system.