Thalassas: An International Journal of Marine Sciences最新文献

The present study was conducted to identify the molluscan species associated with the Posidonia oceanica and Zostera marina meadows in the Marmara Sea. The investigated benthic material was taken from seven stations at depths up to 7 m by utilizing a quadrate sampler (20 (times) 20 cm) and was randomly collected by snorkeling and scuba diving from three stations in 2012. Faunistic examination revealed a total of 73 mollusc species pertaining to the classes of Polyplacophora, Gastropoda, and Bivalvia. Among the identified species Haliotis tuberculata Linnaeus, 1758, Obtusella macilenta (Monterosato, 1880), and Thylaeodus rugulosus (Monterosato, 1878) are new records from the region. The families Rissoidae (13 species), Mytilidae (7 species), and Veneridae (6 species) were found in the greatest number of species, and the most abundant mollusc species included Bittium reticulatum (da Costa, 1778) (63.70% of the total number of individuals), and Rissoa ventricosa Desmarest, 1814 (18.40%). According to Pearson’s correlation analysis, the number of species and the number of specimens exhibited positive correlations with phosphorus (r = 0.86 and r = 0.72, p < 0.05). CCA analysis revealed that Chl-a was correlated with the first axis, whereas salinity, Chl-a, dissolved oxygen, and phosphorus were connected with the second axis.

The introduction and establishment of the bivalves Isognomon bicolor and Isognomon aff. legumen in the South Aegean Sea, specifically on the islands of Chalki and Alimia, marks a significant ecological event. These species, native to different parts of the world, have now been confirmed in the Mediterranean through DNA barcoding and phylogenetic analyses. These methods are crucial for accurate identification within the genus Isognomon, as traditional morphological identification is challenging due to the variable and habitat-dependent shell shapes of these bivalves. Isognomon bicolor is originally from the West Atlantic, while Isognomon aff. legumen hails from the Indo-Pacific region. Their presence in the Mediterranean, specifically in the intertidal and shallow subtidal zones, indicates they have found suitable habitats in their new environment. Over a four-year period of field observations, researchers gathered valuable ecological data, noting the species’ habitat preferences and their establishment dynamics. In July 2024, researchers observed the formation of new, extensive dense aggregations, or beds, of the invasive I. bicolor on the coastal rocks of Chalki and Alimia. The formation of these beds is a clear indicator of a progressing invasion, which poses a significant threat to the native ecosystem. The establishment of I. bicolor and I. aff. legumen could disrupt local biodiversity, outcompete native species, and alter the ecological balance in these regions. This situation underscores the importance of continuous monitoring and the use of advanced identification techniques like DNA barcoding to track and manage invasive species. Such efforts are essential to mitigate the impacts of these invasions and protect native marine ecosystems.

Biofouling assemblages may pose negative effects on navigation activities and marine environment in international ports. Investigating the settlement of these assemblages is important to help in the mitigation of their impacts. Tanjung Priok Port, Jakarta, is the largest and busiest international port in Indonesia, yet the assessment of biofouling assemblages in this port is limited. We analysed differences in the settlement of those assemblages between wet (November 2011 to January 2012) and dry (May to July 2012) seasons over different submersion durations (one, two, and three months). Non-toxic polyvinyl chloride panels of 0.1 m x 0.2 m were submerged vertically at a depth of 1 m as biofouling collectors. Physico-chemical parameters (temperature, salinity, pH, dissolved oxygen, nitrate, nitrite, phosphate, and total suspended solid) and biological parameters (phytoplankton and zooplankton) of the water column were also recorded. The composition of biofouling assemblages significantly differed between wet and dry seasons (p < 0.05), but the assemblage dissimilarity between seasons was smaller after three months of submersion. Tunicates dominated biofouling assemblages during the wet season across all submersion durations. In the dry season, macroalgae were the most dominant group after one month of submersion but replaced by calcareous polychaetes after two and three months of submersion. The seasonal variability of biofouling assemblages was associated with zooplankton diversity and richness, phytoplankton diversity, dissolved oxygen, and nitrate in the water column.

The bogue (Boops boops (L. 1758)), is a commercially important fish species listed within top landed marine species in Turkish fisheries. This study was performed to assess feeding, growth, mortality, and level of exploitation of the population in Mersin and Iskenderun Bay, in the Eastern Mediterranean Sea. The ratio of males to females (1:1.04) was not significantly different from 1:1. The growth profile was positive allometric, except for juveniles. The von-Bertalanffy growth parameters for the combined sexes were L_∞ = 32.991 cm, k = 0.181 years⁻¹ and t₀ = -1.928 years, and growth performance index was Ø = 5.286. Total mortality (Z) was estimated as Z = 1.402, with natural mortality (M) and fishing mortality (F) of M = 1.162 and F = 0.829, respectively. The exploitation ratio was calculated as E = 0.829, indicating that bogue stock that inhabits Mersin and Iskenderun Bay was overexploited. Fishing pressure should therefore be reduced in order to preserve the population. A total of 190 stomach contents were analysed, of which 46 (24%) contained undigested food. The diet consisted of larval and juvenile fish, copepods, shrimps, and squids. The larval and juvenile stages of the invasive Bregmaceros nectabanus were the most prevalent prey items, occurring in 95% of the examined specimens with full stomachs. This serves as a notable example of how an invasive species can emerge as a vital dietary component for native species.

Island bays show different physico-chemical characteristics due to their connection with open ocean water and small catchment area, and the same is expected with the biological forms. Phytoplankton size structure significantly influences the function of pelagic food webs and is controlled by the ambient nutrient concentrations. To quantify the relationship between these two in a tropical island bay and to understand the controlling factors, we analyzed the chlorophyll-a concentration by partitioning into three size classes (0.2—2.0 µm, 2.0—20.0 µm and > 20.0 µm) for two seasonal observations in the Andaman Islands. During winter, the nano-phytoplankton (2.0 – 20.0 µm) dominated, while in spring, micro-phytoplankton (> 20.0 µm) dominated. It was observed that the bay had abundant nutrients, but low chlorophyll a concentrations in winter, whereas the scenario reversed in spring. The phytoplankton community exhibited significant seasonal differences between the inner and outer bay areas. The inner bay was dominated by the nano-phytoplankton in winter and micro-phytoplankton in spring, while nano-phytoplankton and pico-phytoplankton dominated the outer bay. The micro-phytoplankton showed a significant seasonal variation, while the other two functional groups did not. During winter, the micro-phytoplankton showed a good correlation with the nutrient silicic acid, and the nanoplankton correlated with nitrite, nitrate, silicate and TN (Total Nitrogen) implying nano-phytoplankton’s reliance on most of the nutrients including organic nutrient. During spring, micro-phytoplankton correlated with the nutrient nitrate, and the nano-phytoplankton correlated with the organic nutrient total nitrogen (TN) implying its reliance on the organic nutrient.

The study presents the findings of the impact of open cast mining on meio and macro fauna in marine and estuarine ecosystems. Three samples were collected from each ecosystem type to assess benthic abundance and diversity. Our observations indicate that meio and macro benthos abundance is significantly lower in the marine areas directly adjacent to the open cast mining sites. Conversely, higher abundance was noted in estuarine areas, which are not in direct proximity to mining activities. However, diversity levels were found to be similar between the marine and estuarine ecosystems studied. Amongst meio fauna, the species observed were Foraminifera, Tintinnida, Bipalium sp. Globigerina sp. Nematode worms, and Gastropods including diatoms like Coscinodiscus sp, Pleurosigma sp, Nitzschia sp, Skeletonema sp, Coccoliths, Bacillaria sp, Gastrotricha, Copepods and Navicula Hasta. The identified macro-fauna consists of Lamellibranchs shells, Gastropods shells, Bivalve shells, Crustacea, Amphipods and Worms. These findings underscore the ecological consequences of open cast mining on marine and estuarine fauna, highlighting the differential impacts based on proximity to mining activities. The study emphasizes the importance of these results in guiding decision-making processes and framing targeted mitigation measures. Recommendations for mitigation are tailored to the specific processes and characteristics of the study area, aiming to minimize the adverse effects of open cast mining on marine and estuarine benthic communities. This research contributes valuable insights into the environmental implications of industrial activities in coastal areas, offering a scientific basis for sustainable mining and conservation efforts.

Thirteen females of Lernanthropus pomatomi Rathbun , 1887 (Copepoda: Lernanthropidae) and one female of Caligus schistonyx Wilson , 1905 (Copepoda: Caligidae) were recorded in the Bluefish Pomatomus saltatrix (Linnaeus, 1766) (Teleostei: Pomatomidae) (420 mm SL, 1030 g) off the northern coast of the Yucatan Peninsula, Mexico, in the southern Gulf of Mexico. Records of L. pomatomi and C. schistonyx in this region are an extension of their geographic distribution to the tropics, since these parasitic copepods were originally described in P. saltatrix from the northern Gulf of Mexico and North-Western Atlantic Ocean. A summary of recorded Lernanthropus and Caligus species in Mexico is included. Studies on parasitic copepods in Mexico are more frequent in the Mexican Pacific; thus, it is recommended to further document the parasitic copepod diversity in marine fishes from the southern Gulf of Mexico and the Mexican Caribbean.

Rastrelliger kanagurta (Cuvier, 1817), commonly known as the Indian mackerel, is found widely across the coastlines of the Indian Ocean. This study explores the applicability of the Generalized Additive Model (GAM) for predicting the habitat preferences of the Indian mackerel. Data on Indian mackerel catch and oceanographic parameters were collected from January 2017 to April 2019. Parameters such as Sea Surface Temperature (SST), Chlorophyll-a concentration (CHL), Sea Surface Height (SSH), Sea Surface Salinity (SSS), Mixed Layer Depth (MLD), and Ocean Currents (OC) were sourced from the Copernicus Marine Environment Monitoring Service (CMEMS) satellites. Initial ggpairs plot analysis showed positive correlations between Indian mackerel abundance and SSH (p < 0.01, r = 0.19), and negative correlations with SSS (p < 0.01, r = -0.23) and OC (p < 0.05, r = -0.15). GAM results indicated that CHL (p < 0.001), SSS (p < 0.001), SSH (p < 0.001), SST (p < 0.001), and MLD (p < 0.05) significantly influence Indian mackerel catch along the Northwest coast of India. The distribution map revealed high abundance in the coastal waters of Mumbai and Raigad. GAM outputs were employed to generate a spatial prediction map, suggesting the potential for increased catches beyond 50 m depth compared to coastal areas. This study highlights the usefulness of multispectral satellite images in identifying potential fishing grounds. The findings from this research can aid decision-making, reduce fuel costs related to search and fishing operations, and enhance understanding of climate change effects on Indian mackerel distribution.

The reproductive biology of fishes is crucial for providing reliable and scientifically sound recommendations for managing, monitoring, and evaluating fisheries regionally. This study aims to determine the reproductive characteristics of Lutjanus quinquelineatus(Bloch, 1790) in the Terengganu, southern South China Sea, Malaysia. A total of 527 specimens (255 males and 272 females) were collected using trawl net from April 2022 to March 2023. These specimens were measured, with total length ranging between 14.3 cm and 26.7 cm (mean ± SD: 19.1 ± 1.9 cm), and body weight ranging from 38.6 g to 316.8 g (mean ± SD: 119.1 ± 37.8 g). Sex ratio, gonadosomatic index (GSI), hepatosomatic index (HSI), spawning period, fecundity, condition factor (Kn), length at maturity (L_m) and the gonadal maturation stages were assessed in this study. No significant difference (χ2 = 0.54) was observed in the overall monthly sex ratio of male and female (1:1.07). The spawning season is determined by the GSI and gonad maturation stages, extending from February to June with peak periods in March. The evaluation of the relationship between the Kn and the HSI revealed that body energy and lipid storage in the liver may not be crucial factors for gonad development. The batch fecundity of 34 mature females ranged from 17.6 to 25.2 cm in length, with body weight ranging from 79.4 to 279.3 g, yielding 19,314 to 98,880 oocytes. The fecundity increased with gonad weight in contrast to the length and weight of fish. The lengths at maturity for males and females were 20.8 cm and 20.1 cm, respectively. This study offers indispensable information that will update the existing database and contribute to developing effective fishery management strategies in the specified area.

A 50-day feeding trial was conducted to determine the nutraceutical effect of a phospholipid, egg yolk lecithin (EYL) on juvenile silver pompano (Trachinotus blochii). The initial weight of the fish was (14.32 ± 0.12) g. The different dietary supplementation levels of EYL included 0% (EYL₀), 1% (EYL₁), 2% (EYL₂), 3% (EYL₃), and 4% (EYL₄). EYL supplementation has a positive impact on the growth and feed utilization of fish. The specific growth rate and weight gain percentage were significantly greater in the treatment group fed with 3% EYL. Feed utilization was observed to be highest in EYL₃ as feed efficiency ratio (FER) and protein efficiency ratio (PER) were higher in this treatment group when compared with all other treatment groups. The survival rate was observed to be 100% in all the treatment groups. Hemoglobin (Hb), mean corpuscular volume (MCV), packed cell volume (PCV), and red blood cells (RBC) values were greater for EYL₂, EYL₃ and EYL₄ whereas mean corpuscular hemoglobin concentration (MCHC) was unaffected by EYL supplementation. Nitro blue tetrazolium (NBT) activity was highest in the EYL₃ group. Dietary EYL supplementation significantly decreased blood glucose levels in the fish. Highest catalase (CAT) activity in the gills and liver was observed in the treatment group EYL₀. Superoxide dismutase (SOD) activity in the liver was unaffected and SOD activity in gills tended to decrease toward EYL₃ but increased in EYL₄. A significant reduction in the serum total protein concentration, serum globulin concentration, and an increase in serum albumin concentration and A:G ratio with respect to an increase in EYL indicate improved health. Serum triglycerides, creatinine, and uric acid were unaffected by EYL supplementation. However, HDL-cholesterol exhibited an increasing trend with an increasing EYL but decreased thereafter in EYL₄. These findings suggest a potential benefit of EYL inclusion above 1% up to 3% in the diets for promoting growth and health in juvenile silver pompano.