Marine Communities Research Articles

Recruitment and growth of the xylophagous bivalve Bankia martensi ( ) with different levels of wood biofouling species cover

Teredinid bivalves (shipworms) are the main wood degraders in marine environments. However, little is known about the biological interactions between these marine wood borers and wood-associated biofouling species. Filter-feeding species and seaweeds are frequent biofoulers on the submerged wood. Using the marine xylophagous bivalve Bankia martensi (Stempell, 1899) as a model, we hypothesized that increasing the abundance of biofouling species on wood will decrease the recruitment and subsequent growth of the shipworm B. martensi. During the springs of 2020 and 2021, experiments manipulating biofouling cover were carried out using pine panels in Bahía Metri, southern Chile. Three experimental levels of biofouling cover were established (low: 0%–10%, intermediate: 40%–50%, and high: 90%–100%). After five months, the number of B. martensi perforations (as proxy as larval settlement density) and specimen sizes (length, width and volume) in the panels were measured. An inverse relationship between the perforation densities of B. martensi and biofouling cover on the wooden panels was observed. The most frequent biofouling species were mussels and seaweeds which tended to settle on the upper and lateral surfaces, while acorn barnacles and bryozoans were more frequent on the lower surface. Bankia martensi perforations were reduced with increasing biofouling cover. The number of perforations varied according to the panel surface, higher density on the upper and lateral surfaces and lower on the underside. Bankia martensi specimens were larger, both in length and in volume, in panels with low biofouling compared to intermediate and high biofouling cover, while width did not vary with treatment. Our results suggest that the biofouling cover decreases B. martensi recruitment and growth rates, which in turn reduces the wood degradation rate caused by this teredinid. Future manipulative experiments with selected biofouling species (filter-feeders, such as mussels and barnacles), as well as incorporating measurements of reproductive traits of shipworms could help in understanding the biological interactions between these marine communities of wood-boring and biofouling species.

Is it worthy to use environmental DNA instead of scientific trawling or video survey to monitor taxa in soft-bottom habitats?

Non-extractive techniques such as video analysis are increasingly used by scientists to study marine communities instead of extractive methods such as trawling. Currently, environmental DNA (eDNA) analysis is seen as a revolutionary tool to study taxonomic diversity. We aimed to determine which method is the most appropriate to describe fish and commercial invertebrate diversity comparing bottom trawl hauls, video transects and seawater eDNA. Our results reveal that video detected the lowest number of taxa and trawling the highest. eDNA analysis is powerful to describe marine bony fish communities, but some taxa of importance for the ecosystem such as elasmobranchs, crustaceans or molluscs are poorly detected. This may be due to several factors such as marker specificity, incomplete reference gene databases or low DNA release in the environment. For now, the various methods provide different information and none is exhaustive enough to be used alone for biodiversity characterisation.

Micromorphic brachiopods from the early Permian (Kungurian) of Hidalgo, Mexico. Stratigraphic, paleoenvironmental and paleobiogeographic significance

This work describes for the first time a fauna of micromorphic brachiopods from Mexico. The biota comprises Permian species of the order Productida: Dyoros (Dyoros) extensiformis, Quadrochonetes girtyi, Rugaria hessensis, Fimbrinia ovata, as well as a productid indeterminate. The samples were located in the Calnali 2 section, belonging to the Tuzancoa Formation. The Kungurian (upper Cisuralian) relative age of the section was established by employing brachiopods, which were associated with bivalves, crinoids, trilobites, and bryozoans. The rocks with invertebrates are interbedded with strata bear plant remains. Sedimentological traits and preservation of brachiopods and associated fauna suggest that the marine community was deposited in a subtidal shallow and restricted environment with very low energy and continuous terrigenous input. On the other hand, the productid indeterminate is the largest brachiopod and displays the worst preservation, with evident traits suggesting that it was transported from a faraway region of the coast. Given that all taxa were previously identified in different units of Texas, considered a region where the Grandian Province was extended, it can be proposed that brachiopods of the Tuzancoa Formation also belonged to the same province. Thus, apart from New Mexico and Texas (USA), Huehuetenango (Guatemala), Palmarito (Venezuela), and Coahuila and Chiapas (Mexico), also Hidalgo's early Permian fauna could be included in the same biotic province.

Marine heatwave-driven mass mortality and microbial community reorganisation in an ecologically important temperate sponge.

Marine heatwaves (MHWs) are increasing in frequency, duration and intensity, disrupting global marine ecosystems. While most reported impacts have been in tropical areas, New Zealand experienced its strongest and longest MHW in 2022, profoundly affecting marine sponges. Sponges are vital to rocky benthic marine communities, with their abundance influencing ecosystem functioning. This study examines the impact of this MHW on the photosynthetic sponge Cymbastella lamellata in Fiordland, New Zealand. We describe the extent, physiological responses, mortality, microbial community changes and ecological impact of this MHW on C. lamellata. The Fiordland MHW reached a maximum temperature of 4.4°C above average, lasting for 259 days. Bleaching occurred in >90% of the C. lamellata Fiordland population. The population size exceeded 66 million from 5 to 25 m, making this the largest bleaching event of its kind ever recorded. We identified the photosynthetic symbiont as a diatom, and bleached sponges had reduced photosynthetic efficiency. Post-MHW surveys in 2023 found that over 50% of sponges at sampling sites had died but that the remaining sponges had mostly recovered from earlier bleaching. Using a simulated MHW experiment, we found that temperature stress was a driver of necrosis rather than bleaching, despite necrosis only rarely being observed in the field (<2% of sponges). This suggests that bleaching may not be the cause of the mortality directly. We also identified a microbial community shift in surviving sponges, which we propose represents a microbial-mediated adaptive response to MHWs. We also found that C. lamellata are key contributors of dissolved organic carbon to the water column, with their loss likely impacting ecosystem function. We demonstrate the potential for MHWs to disrupt key marine phyla in temperate regions, highlighting how susceptible temperate sponges globally might be to MHWs.

Short-term microplastic effects on marine meiofauna abundance, diversity and community composition.

Due to the copious disposal of plastics, marine ecosystems receive a large part of this waste. Microplastics (MPs) are solid particles smaller than 5 millimeters in size. Among the plastic polymers, polystyrene (PS) is one of the most commonly used and discarded. Due to its density being greater than that of water, it accumulates in marine sediments, potentially affecting benthic communities. This study investigated the ingestion of MP and their effect on the meiofauna community of a sandy beach. Meiofauna are an important trophic link between the basal and higher trophic levels of sedimentary food webs and may therefore be substantially involved in trophic transfer of MP and their associated compounds. We incubated microcosms without addition of MP (controls) and treatments contaminated with PS MP (1-µm) in marine sediments at three nominal concentrations (103, 105, 107particles/mL), for nine days, and sampled for meiofauna with collections every three days. At each sampling time, meiofauna were collected, quantified and identified to higher-taxon level, and ingestion of MP was quantified under an epifluorescence microscope. Except for Tardigrada, all meiofauna taxa (Nematoda, turbellarians, Copepoda, Nauplii, Acari and Gastrotricha) ingested MP. Absorption was strongly dose dependent, being highest at 107 particles/mL, very low at 105 particles/mL and non-demonstrable at 103 particles/mL. Nematodes accumulated MP mainly in the intestine; MP abundance in the intestine increased with increasing incubation time. The total meiofauna density and species richness were significantly lower at the lowest MP concentration, while at the highest concentration these parameters were very similar to the control. In contrast, Shannon-Wiener diversity and evenness were greater in treatments with low MP concentration. However, these results should be interpreted with caution because of the low meiofauna abundances at the lower two MP concentrations. At the highest MP concentration, abundance, taxonomic diversity and community structure of a beach meiofauna community were not significantly affected, suggesting that MP effects on meiofauna are at most subtle. However, lower MP concentrations did cause substantial declines in abundance and diversity, in line with previous studies at the population and community level. While we can only speculate on the underlying mechanism(s) of this counterintuitive response, results suggest that further research is needed to better understand MP effects on marine benthic communities.

Model Pengelolaan Sumber Daya Kelautan dan Kemaritiman

Introduction: Indigenous people who live on small islands are quite large in number compared to the available natural resources. So it can be said that it is not enough to meet the basic needs of indigenous peoples, for a certain period of time. Therefore, the idea was born to create legal regulations that could regulate and organize all the potential of marine and maritime resources so that they could be used wisely.Purposes of the Research: to formulate the formulation of a Marine and Maritime Resources Management Model in Central Maluku Regency.Methods of the Research: This research was conducted using an empirical juridical approach which is a descriptive qualitative analysis study. The research seeks to describe the Marine and Maritime Resource Management Model in Central Maluku Regency. The way the empirical juridical or sociological juridical method works in this research proposal is from the results of collecting and finding data and information through literature study of the basic assumptions or presumptions used in answering the problems in this research, then inductive-verification testing is carried out on the latest facts available. exists in society, thus the truth in a study has been declared reliable without having to go through a rationalization process.Results of the Research: To minimize conflicts and disputes that occur in the marine and maritime customary rights community, there must be a formulation of a model for regulating marine and maritime management in Central Maluku Regency involving all cuttings holders.

Salinity Stress Acclimation Strategies in Chlamydomonas sp. Revealed by Physiological, Morphological and Transcriptomic Approaches.

Climate changes may include variations in salinity concentrations at sea by changing ocean dynamics. These variations may be especially challenging for marine photosynthetic organisms, affecting their growth and distribution. Chlamydomonas spp. are ubiquitous and are often found in extreme salinity conditions. For this reason, they are considered good model species to study salinity adaptation strategies. In the current study, we used an integrated approach to study the Chlamydomonas sp. CCMP225 response to salinities of 20‱ and 70‱, by combining physiological, morphological, and transcriptomic analyses, and comparing differentially expressed genes in the exponential and stationary growth phases under the two salinity conditions. The results showed that the strain is able to grow under all tested salinity conditions and maintains a surprisingly high photosynthetic efficiency even under high salinities. However, at the highest salinity condition, the cells lose their flagella. The transcriptomic analysis highlighted the up- or down-regulation of specific gene categories, helping to identify key genes responding to salinity stress. Overall, the findings may be of interest to the marine biology, ecology, and biotechnology communities, to better understand species adaptation mechanisms under possible global change scenarios and the potential activation of enzymes involved in the synthesis of bioactive molecules.

Morphological innovation did not drive diversification in Mesozoic-Cenozoic brachiopods.

Over long spans of geological time, various groups of organisms may wax and wane, experiencing times of apparent success and contraction. These rises and falls are often said to reflect either opportunities created by climate change or the relative success of innovative characteristics. Phylum Brachiopoda was one of the most successful marine clades before the Permian/Triassic mass extinction (PTME), but after this event, they became marginal components of marine communities through to the present day. How brachiopod morphological innovations reacted to swiftly declining diversity has long remained poorly understood. Here we analyse morphological evolution over the 300 Myr (Permian-Quaternary) history of the four major Mesozoic-Cenozoic brachiopod orders (Terebratulida, Rhynchonellida, Spiriferinida, Athyridida). Unexpectedly, their disparities reached or exceeded pre-PTME levels, but were decoupled from generic richness, which was generally low. Distribution of taxa in morphospace and shifts in centroid indicate that all four orders exploited new morphospaces when adapting to post-Permian environments. A comparison of morphospace occupation and diversity evolution suggests that the high extinction rate of brachiopods and the limited diversification of new forms may have accounted for the depauperate nature of modern-day brachiopods.

Erosion of fish trophic position: an indirect effect of fishing on food webs elucidated by stable isotopes.

Fishing has significant trophodynamic impacts on marine communities, including reductions in the mean trophic position (TP) of the ecosystem resulting from a decrease in the abundance and size of species and individuals with high TPs. This study demonstrates the erosion of fish TP, an additional process that results in lower TP of individuals of a given size, which may exacerbate the effects of fishing on the food web. A stable isotope approach based on the tRophicPosition Bayesian method was used to quantify the TP of 12 target marine species at a given length, and compare their TP between fishery-restricted areas and trawled areas. The results show a difference in the TP of six benthic and apical nekto-benthic predators, which feed in the median at about 0.5 TP lower in trawled areas. It appears that current 'fishing down marine food webs' analyses may underestimate the trophic effects of fishing. Accounting for changes in trophodynamics of individuals at a given size is important to detect indirect effects through food web interactions. The application of a trawling ban may lead to the restoration of lost trophic structure; however, trophic changes may occur more slowly than changes in biomass. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Ecological control of the Pelsonian colonisation event (Anisian, Triassic) leading to the first settlement of Tetractinella-beds (Brachiopoda) in the Iberian palaeomargins. Palaeobiogeographical and biostratigraphical significance

Marine benthic biota recovery after the Permian/Triassic extinction is still a challenging topic in several fossil clades such as brachiopods. In fact, available data from the Early-Middle Triassic are scarce worldwide and their global record derives from limited localities throughout the Tethys Ocean. This work presents the first record of the Anisian Tetractinella-beds (Brachiopoda, Athyridida) in the peri-Iberian epicontinental platforms established in the westernmost Tethys margins. Their utility as a reliable biohorizon marker is emphasised as they provide an effective tool for age calibration and correlation in the middle Anisian (Pelsonian) successions, also supported by the co-occurring fossil assemblage. In the South-Iberian Palaeomargin, Tetractinella-beds occur in an intensively-burrowed shallow-marine succession. The rich ichnological content has been exhaustively evaluated in order to assess the ecological factors controlling the development of the brachiopod fauna. Three ichnoassemblages are documented dominated by Oravaichnium, Balanoglossites and Thalassinoides, respectively. The gathered faunal, ichnological, taphonomical, and sedimentological data reveal an alternation of sea-level changes influencing the composition of the Anisian marine communities. The first stage consists of near-shore restricted environments sporadically disturbed by short-term shallow-marine interludes, characterised by the presence of Oravaichnium and its associated fauna. Subsequently, the Pelsonian transgression event is recorded (MID-2), documented by a firm-ground surface pointed out by the development of a Balanoglossites surface, followed by the highstand, when shallow epicontinental environments developed in connection with open-marine areas. This phase involved the spreading of Tetractinella and deep-water bivalves. Finally, near-shore restricted conditions were re-established typified by Oravaichnium and the last occurrences of Tetractinella, with the disappearance of the open sea-water fauna. The maximum flooding reached after the Pelsonian transgression facilitated new palaeobiogeographical migration routes, allowing for an Alpine-Germanic dispersion of taxa throughout the North-South epicontinental Tethyan seaway as well as the earliest first faunal migration event from the Sephardic Bioprovince northwards to the South-Iberian palaeomargin.

Marine Debris Harbor Unique, yet Functionally Similar Cryptofauna Communities.

Human-made debris is entering the ocean at alarming rates. These artificial structures are becoming habitats for small marine taxa known as cryptofauna. Cryptofauna are among the most essential reef taxa; however, little is known about these organisms, let alone their fate considering degrading coral reefs and increasing anthropogenic disturbance. The current study explores differences in naturally occurring cryptofauna biodiversity compared to those inhabiting benthic marine debris. To explore this difference, we measured invertebrate diversity from autonomous reef monitoring structures (ARMS) located on patch reefs along the middle Florida Keys reef tract. ARMS were used as a proxy for natural structure to compare to marine debris removed from five reef locations. Plastic debris was the most abundant of all the debris material collected. Wood and concrete were identified as covariates since they are sourced from wooden lobster traps. Taxa diversity varied significantly between ARMS and debris, indicating that each structural unit contained significantly different and diverse communities. The most influential taxa identified included commensal shrimps, hermit crabs, brittle stars, segmented worms, and several families of crabs. Additionally, while functional richness increased with taxa richness for ARMS communities, debris communities showed decreasing functional richness and high functional similarity, suggesting a specialization of debris-specific taxa. Overall, these data assist in better understanding of the marine community ecology surrounding anthropogenic marine debris for future debris removal and management practices for comprehensive reef health.

Size‐based indicators of unexploited deep‐sea community in the Colombian Caribbean Sea

AbstractComposition, size distribution, structure, and function of deep‐sea marine communities must be understood before they are impacted by anthropogenic effects. The deep‐sea ecosystem of the Colombian Caribbean Sea is unexploited with no fishing activity ever registered. We quantified the current state of the marine community using body size distribution (size‐spectra), size‐based indicators, minimum length (LMIN), maximum length (LMAX), average length (Lmean), standard deviation of length (LSD), 10th and 90th percentiles of the length distribution, Shannon–Wiener diversity (H′), and Pielou's evenness (J′) to generate a baseline of potential ecological indicators that contribute to management and conservation of the Colombian bento‐demersal community of deep‐sea marine ecosystem. Sampling was in the Colombian Caribbean Sea at 58 stations during four samplings in August and December 2009, 21 stations in March and May 2010, and 45 stations from August to December 2020, using the swept area method, at depths of 200–550 m. Catches included &gt;50% families and species of fish, followed by 27 families (30%) and 33 and species (37%) of crustaceans. Chondrichthyes included 14% families and 9–11% species. Cephalopods included 2–3% families and 1–4% species. Size‐spectra analysis confirmed expected values for unexploited communities in three sampling years for teleostei, crustacea, and whole community.

A novel indicator of anthropogenic influence on the fluctuability and stability of phytoplankton community composition

Marine community composition is expected to be relatively stable in a natural environment over time but shift under increasing anthropogenic disturbances. In coastal waters, diatoms and dinoflagellates are two dominant phytoplankton functional groups. In this study, we developed an areal phytoplankton community composition index (APCI) that is based on the area of a scatter plot of dinoflagellate abundance (y-axis) vs diatom abundance (x-axis) using a time window of 1 year, 2 years or 3 years data. An APCI allows an ecological interpretation: it represents the fluctuability of a community composition within a time window and a temporal change between two neighbouring APCIs in a time series represents the stability of the composition. We used a 28-yr time series of monthly data on diatom and dinoflagellate abundance at four stations in Tolo Harbour and Channel (Tolo), Hong Kong to test the hypothesis that temporal changes in APCIs indicate environmental disturbances and to examine the applicability of APCI to indicate changes in nutrient conditions. We calculated the area (APCI) of a scatter plot of monthly data for 1-year, 2-year and 3-year windows, referred to as APCI-1y, −2y and -3y, respectively. The results show that, the fluctuability, is larger in APCI-3y than in APCI-1y, while the stability is stronger as temporal changes between neighbouring APCI-3y are smaller than between APCI-1ys. Temporal trends of APCIs are significantly correlated with those of dissolved inorganic nitrogen and phosphate concentration, which have declined after the implementation of a sewage diversion management plan in 1998. Hence, the APCI method is likely a robust indicator to assess a response of the phytoplankton community composition in a water body to environmental disturbances.

Oceanic seabirds chase tropical cyclones

In late summer and autumn, the passage of intense tropical cyclones can profoundly perturb oceanic and coastal ecosystems. Direct negative effects on individuals and marine communities can be dramatic, especially in the coastal zone,1,2,3,4 but cyclones can also enhance pelagic primary and secondary production.5,6,7,8,9 However, cyclone impacts on open ocean marine life remain poorly understood. Here, we investigate their effects on the foraging movements of a wide-ranging higher predator, the Desertas petrel (Pterodroma deserta), in the mid-latitude North Atlantic during hurricane season. Contrary to previously studied pelagic seabirds in tropical and mid-latitude regions,10,11 Desertas petrels did not avoid cyclones by altering course, nor did they seek calmer conditions within the cyclone eye. Approximately one-third of petrels tracked from their breeding colony interacted with approaching cyclones. Upon encountering strong winds, the birds reduced ground speed, likely by spending less time in flight. A quarter of birds followed cyclone wakes for days and over thousands of kilometers, a behavior documented here for the first time. Within these wakes, tailwind support was higher than along alternative routes. Furthermore, at the mesoscale (hours-weeks and hundreds of kilometers), sea surface temperature dropped and surface chlorophyll sharply increased, suggesting direct effects on ocean stratification, primary production, and therefore presumably prey abundance and accessibility for surface-feeding petrels. We therefore hypothesize that cyclone wakes provide both predictably favorable wind conditions and foraging opportunities. As such, cyclones may have positive net effects on the demography of many mid-latitude pelagic seabirds and, likely, other marine top-predators.

A sedimentary DNA record of the Atacama Trench reveals biodiversity changes in the most productive marine ecosystem.

The hadopelagic environment remains highly understudied due to the inherent difficulties in sampling at these depths. The use of sediment environmental DNA (eDNA) can overcome some of these restrictions as settled and preserved DNA represent an archive of the biological communities. We use sediment eDNA to assess changes in the community within one of the world's most productive open-ocean ecosystems: the Atacama Trench. The ecosystems around the Atacama Trench have been intensively fished and are affected by climate oscillations, but the understanding of potential impacts on the marine community is limited. We sampled five sites using sediment cores at water depths from 2400 to ~8000 m. The chronologies of the sedimentary record were determined using 210Pbex. Environmental DNA was extracted from core slices and metabarcoding was used to identify the eukaryote community using two separate primer pairs for different sections of the 18S rRNA gene (V9 and V7) effectively targeting pelagic taxa. The reconstructed communities were similar among markers and mainly composed of chordates and members of the Chromista kingdom. Alpha diversity was estimated for all sites in intervals of 15 years (from 1842 to 2018), showing a severe drop in biodiversity from 1970 to 1985 that aligns with one of the strongest known El Niño events and extensive fishing efforts during the time. We find a direct impact of sea surface temperature on the community composition over time. Fish and cnidarian read abundance was examined separately to determine whether fishing had a direct impact, but no direct relation was found. These results demonstrate that sediment eDNA can be a valuable emerging tool providing insight in historical perspectives on ecosystem developments. This study constitutes an important step toward an improved understanding of the importance of environmental and anthropogenic drivers in affecting open and deep ocean communities.

Social sustainability in Bangladesh marine fisheries management: A case from Hatiya fishing community

Social sustainability in fisheries focuses on retaining or improving societal welfare in the fishery system without threatening its long-term financial benefits and socio-cultural welfare. However, often social sustainability issues are ignored while implementing any fisheries management actions rather than only focusing on economic and environmental sustainability issues. This study assesses the social sustainability in Bangladesh marine fisheries management gaining insights from the coastal and marine fisheries-dependent communities of Hatiya Upazila in 2021–2022 using a mixed method approach especially focusing on the social issues during the marine fishing ban. Results have shown positive effects on fish production but negative implications on the socio-economic circumstances of the reliant households after the implementation of the marine fishing ban. During the ban, the ability of around 33 % of fisher households to have 3 meals a day has drastically reduced to 2 or 1 meal per day. Households' average fish intake has reduced from 7 kg to 4 kg per week during the ban. Similarly, there have been detrimental effects on family relationships, healthcare access and children's education during the ban. Moreover, pregnant women and children have suffered greatly from protein deficiencies as fishers could not buy protein-rich foods for their families during the ban. Due to the shortage of alternate income-generating activities (AIGAs), almost 71 % of fishers became indebted during the ban. To assist the fishers during the ban, the government has implemented several measures, such as offering incentives (40 kg of rice per registered fisherman per month) and/or AIGA but those are too scant to recompense for the loss that is incurred due to the fishing ban. Finally, this study provides some way forward to bring social sustainability that is affected due to the marine fishing ban as well as to partly meet the targets of Sustainable Development Goals 1, 2, 14 and 15.

Response of the phytoplankton size fractions along environmental gradients from an oxygen minimum zone in the central Mexican Pacific

The marine phytoplankton community responds to latitudinal, longitudinal (coast to ocean), and vertical environmental gradients, an important subject in Oxygen minimum zones (OMZ). The phytoplankton structure and the effect of environmental gradients along the central Mexican Pacific, an area within an OMZ, were studied, especially the importance of size fractions and taxonomic groups. A combination of various methods and protocols, such as microscopic analysis, flow cytometer, and pigment analysis, were followed in this study. Oceanographic conditions included thermal gradients along the study area and unreported evidence of a weak upwelling in the southern zone (Acapulco). Vertical distribution of chlorophyll a showed subsurface maxima (SCM, 15-45 m depth) in all stations, and deeper chlorophyll-a maxima (DCM, 85-95 m depth) in more oceanic stations. Chain-forming diatoms dominated in the northern zone stations. Prochlorococcus, Synechococcus, and picoeukaryotes abundances ranged between 0.01 to 21.7 cells×104 mL-1, although most samples showed the highest contribution to biomass (47.95 μg C L-1) by picoeukaryotes. Expected tendencies of Prochlorococcus distribution were observed: highest densities coincided with the DCM and divinyl chlorophyll-a distribution at oceanic stations. Fucoxanthin had the highest concentrations, whereas fucoxanthin and zeaxanthin concentrations were higher at SCM depths. We documented the co-dominance of the pico- and microplankton: picoplankton was important at the DCM, related to oligotrophic and more stratified water column, whereas microplankton prevailed in coastal stations, with mixed water column, high nutrient concentrations, and diatoms as the dominant group. Picoeukaryotes abundances were related to the concentration of prasinoxanthin, which suggests an important mamiellophyte component not previously revealed.

A comparison study of liability of the carrier in the International Conventions on the Carriage of Goods By Sea

The introduction of the four conventions, namely the Hague Rules, Hague Visby Rules, Hamburg Rules, and Rotterdam Rules is to establish a uniform and harmonized regime governing the international carriage of goods by sea. The rules on the carrier’s liability are the central issues of these conventions which directly connect to the allocation of risks between the carrier and cargo interests. However, the solutions adopted in these Conventions are not likely to satisfy all parties in the international marine community and have faced various criticisms. This research will look at the liability of the carrier regime under these four Conventions. It will examine, by comparative analytical method, the regulation of carrier’s liability in the four Conventions and the similarities and differences between them. It concludes among other things that the Rotterdam Rules deal with the liability of carrier rules better than the older conventions.

Diversity and seasonal occurrence of haptophyta in northern South China Sea through size-fractionated metabarcoding

Haptophyta plays a key role in marine pico-nanoeukaryote communities but information on their diversity and ecology is extremely limited. A total of 103 water samples were collected in northern South China Sea to assess the diversity of haptophyta through metabarcoding targeting 18S V4 rDNA. Furthermore, we investigated the potential genetic differentiation among seasonal occurring Phaeocystis globosa using the high resolution molecular marker pgcp1. 18S V4 rDNA metabarcoding dataset revealed 41 species of haptophytes, with 16 of them as the first record in this region. Notably, six harmful species were detected, including Chrysochromulina leadbeateri, Phaeocystis globosa, and Prymnesium parvum. The pgcp1 marker revealed two clades of Phaeocystis globosa and both of them were present around the year. Clade I was found to predominate in warm season, while Clade III tended to bloom in cold waters. Our results highlight the risk potential of harmful haptophytes in the northern South China Sea.

Comparative analysis of microbiome inhabiting oxygenated and deoxygenated habitats using V3 and V6 metabarcoding of 16S rRNA gene

We examine how oxygen levels and the choice of 16S ribosomal RNA (rRNA) tags impact marine bacterial communities using Next-Generation amplicon sequencing. Analyzing V3 and V6 regions, we assess microbial composition in both Oxygen minimum zones (OMZ) and non-OMZ (NOMZ) areas in the Arabian Sea (AS) and the Central Indian Ocean basin (CIOB) respectively. Operational taxonomic units (OTUs) at 97% similarity showed slightly higher richness and diversity with V6 compared to V3. Vertical diversity patterns were consistent across both regions. NOMZ showed greater richness and diversity than OMZ. AS and CIOB exhibited significant differences in bacterial community, diversity, and relative abundance at the order and family levels. Alteromonadaceae dominated the OMZ, while Pelagibacteraceae dominated the NOMZ. Synechococcaceae were found exclusively at 250 m in OMZ. Bacteria putatively involved in nitrification, denitrification, and sulfurylation were detected at both sites. Dissolved oxygen significantly influenced microbial diversity at both sites, while seasonal environmental parameters affected diversity consistently, with no observed temporal variation.