Marine Ecosystems Research Articles

Atmospheric Precursors of Skillful SST Prediction in the Northeast Pacific

Abstract Forecasts of sea surface temperature anomalies (SSTAs) provide essential information to stakeholders of marine resources in coastal ecosystems, such as the California Current Large Marine Ecosystem (CCLME), at management-relevant monthly-to-annual time scales. Diagnosing dynamical sources of predictability and the mechanisms differentiating skill among forecasts is required for verification and improvement in operational forecasting systems. Using retrospective forecasts (1982–2020) from a four-member subset of the North American Multi-Model Ensemble (NMME), we evaluate the conditional skill of SSTA forecasts in the CCLME at monthly resolution for lead times up to 10.5 months. Forecasts from ensemble members with relatively small SSTA errors at shorter lead times retain higher skill at longer lead times, with the most substantial and long-lasting increases for forecasts initialized in the fall and early spring. The “best” low-error SSTA forecasts are characterized by increased skill in the prediction of North Pacific atmospheric circulation [sea level pressure (SLP) and 200-hPa geopotential height] the month prior to the evaluation of SSTA errors in the CCLME and exhibit more realistic progressions of anomalous SLP. The Pacific meridional mode (PMM) emerges as a diagnostic of skillful North Pacific atmosphere–ocean coupling, as forecasts that correctly simulate the PMM and its associated SLP variability increase the SSTA prediction skill in the CCLME in the fall through spring. Predictable coupled ocean–atmosphere modes provide a target for enhancing predictability with early detection of the onset of a deterministic progression emerging from stochastic atmospheric variability. Significance Statement Global forecast systems provide near-term climate predictions that inform the management of marine resources, such as those of the California Current Large Marine Ecosystem. In this study, we probe the processes which lead forecasts to succeed or fail at predicting sea surface temperatures in the California Current at seasonal time scales among retrospective forecasts from the North American Multimodel Ensemble. We demonstrate that forecasts which best simulate sea surface temperatures at the earliest lead times sustain advantages in forecast skill and find that correctly simulating extratropical atmospheric circulation increases the predictive skill of sea surface temperatures in the northeast Pacific in the following lead times. Our results offer North Pacific atmospheric circulation as a target for forecast model improvement that would additionally enhance ocean forecasts.

Sea cucumbers and their symbiotic microbiome have evolved to feed on seabed sediments

Sea cucumbers are predominant deposit feeders in benthic ecosystems, providing protective benefits to coral reefs by reducing disease prevalence. However, how they receive sufficient nutrition from seabed sediments remains poorly understood. Here, we investigate Holothuria leucospilota, an ecologically significant tropical sea cucumber, to elucidate digestive mechanisms underlying marine deposit-feeding. Genomic analysis reveals intriguing evolutionary adaptation characterized by an expansion of digestive carbohydrase genes and a contraction of digestive protease genes, suggesting specialization in digesting microalgae. Developmentally, two pivotal dietary shifts, namely, from endogenous nutrition to planktonic feeding, and from planktonic feeding to deposit feeding, induce changes in digestive tract enzyme profiles, with adults mainly expressing carbohydrases and lipases. A nuanced symbiotic relationship exists between gut microbiota and the host, namely, specific resident bacteria supply crucial enzymes for food digestion, while other bacteria are digested and provide assimilable nutrients. Our study further identifies Holothuroidea lineage-specific lysozymes that are restrictedly expressed in the intestines to support bacterial digestion. Overall, this work advances our knowledge of the evolutionary innovations in the sea cucumber digestive system which enable them to efficiently utilize nutrients from seabed sediments and promote food recycling within marine ecosystems.

From marine neglected substrata new fungal taxa of potential biotechnological interest: the case of Pelagia noctiluca

IntroductionThe marine environment is extremely complex and exerts strong evolutionary pressure often leading to the appearance of microbial strains with new metabolic competencies. Microorganisms in marine ecosystems are still largely unknown and should be explored and conserved for biodiversity preservation, possible ecosystem restoring, and other applications. Biodiversity conservation should become a basic ecological strategy of particular significance in relation to global change. In this context, the present research aimed at exploring the culturable mycobiota associated with the jellyfish Pelagia noctiluca, never studied before. In addition, the isolated strains were tested for potential application (antimicrobial activity and presence of genes related to the production of secondary metabolites).MethodsFive jellyfishes were collected in the coastal area of Giglio Island and processed to isolate epizoic fungi. The strains were identified using a polyphasic approach (morphological, physiological, and molecular) and their salt preference was also investigated. The antifungal and antibacterial activity were tested for each strain with agar plug diffusion test. The presence of some key genes related to the main pathways for the production of secondary metabolites in fungi, polyketide synthases (PKSs), and non-ribosomal peptide synthase (NRPSs), was also assessed.ResultsA total of 164 isolates were obtained; after the dereplication, 40 morphotypes, and 23 species were identified. The phylogenetic analyses suggested the presence of new taxa belonging to Pleosporales: two new genera and species, and a new species of Tamaricicola. The detected mycobiota showed a relatively high diversity, if compared to other epizoic fungal communities. All isolated strains were marine fungi as confirmed by their salt preference and marked euryhalinism. The genes related to the two main pathways for the production of secondary metabolites in fungi, PKSs and NRPSs, were identified in four and nine strains, respectively. The antimicrobial activity was revealed in 70% of the strains, including the new taxa. The abundance of bioactive strains may be related to the potential involvement of epizoic fungi in host defense strategies. Moreover, these strains could show a high potential for further biotechnological applications particularly in the case of new taxa. All strains are maintained in culture collections.

Ex vivo and in vitro methods as a platform for studying anthropogenic effects on marine mammals: four challenges and how to meet them

Marine mammals are integral to global biodiversity and marine health through their roles in coastal, benthic, and pelagic ecosystems. Marine mammals face escalating threats from climate change, pollution, and human activities, which perturb their oceanic environment. The diverse biology and extreme adaptations evolved by marine mammals make them important study subjects for understanding anthropogenic pressures on marine ecosystems. However, ethical and logistical constraints restrict the tractability of experimental research with live marine mammals. Additionally, studies on the effects of changing ocean environments are further complicated by intricate gene-environment interactions across populations and species. These obstacles can be overcome with a comprehensive strategy that involves a systems-level approach integrating genotype to phenotype using rigorously defined experimental conditions in vitro and ex vivo. A thorough analysis of the interactions between the genetics of marine mammals and their exposure to anthropogenic pressures will enable robust predictions about how global environmental changes will affect their health and populations. In this perspective, we discuss four challenges of implementing such non-invasive approaches across scientific fields and international borders: 1) practical and ethical limitations of in vivo experimentation with marine mammals, 2) accessibility to relevant tissue samples and cell cultures; 3) open access to harmonized methods and datasets and 4) ethical and equitable research practices. Successful implementation of the proposed approach has the potential impact to inspire new solutions and strategies for marine conservation.

A systematic review on analytical methods of the neurotoxin β-N-methylamino-L-alanine (BMAA), and its causative microalgae and distribution in the environment

β-N-Methylamino-L-alanine (BMAA), a neurotoxin produced by various microalgal groups, is associated with neurodegenerative diseases and is considered a major environmental factor potentially linked to sporadic amyotrophic lateral sclerosis. This study systematically reviews the analytical methods used to study BMAA in publications from 2019 to the present. It also investigates the causative microalgae of BMAA and its geographical distributions in aquatic ecosystems based on studies conducted since 2003. A comprehensive search using the Web of Science database revealed that hydrolysis for extraction (67%), followed by quantification using LC-MS/MS (LC: 84%; MS/MS: 88%), is the most commonly employed method in BMAA analysis. Among analytical methods, RPLC-MS/MS had the highest percentage (88%) of BMAA-positive results and included a high number of quality control (QC) assessments. Various genera of cyanobacteria and diatoms have been reported to produce BMAA. The widespread geographical distribution of BMAA across diverse ecosystems highlights significant environmental and public health concerns. Notably, BMAA accumulation and biomagnification are likely more potent in marine or brackish water ecosystems than in freshwater ecosystems, potentially amplifying its ecological impacts. Future research should prioritize advanced, sensitive methods, particularly LC-MS/MS with as many QC assessments as possible, and should expand investigations to identify novel microalgal producers and previously uncharted geographical areas, with a special focus on marine or brackish water ecosystems. This effort will enhance our understanding of the environmental distribution and impacts of BMAA.

Ups and downs: copepods reverse the near-body flow to cruise in the water column

Copepods are negatively buoyant organisms actively participating in large-scale vertical migrations as primary consumers in marine ecosystems. As such, these organisms need to overcome their own weight to swim upwards, incurring extra energy costs that are not offset by any mechanism intrinsic to drag-based propulsion. While copepod vertical migrations are well documented, it is still unclear how they achieve extensive upward cruising despite this limitation. In this study, we found suction to be a compensatory mechanism enhancing thrust in upward-swimming copepods. Using experimentally derived velocity and pressure fields, we observed that copepods pull water in front of them to generate sub-ambient pressure gradients when cruising upward, thereby inducing an upstream suction force to complement the thrust produced by the legs. Contrary to expectations that drag always dominates the leg recovery phase, we found that the upstream suction generates net thrust for about a third of the recovery stroke. In contrast, downward-swimming copepods push rather than pull on water and do not benefit from thrust-enhancing suction effects during the recovery stroke. Differences in the induced flows are associated with contrasting leg kinematics, indicating a response to the body orientation rather than a fixed effect. These results offer insights into an important swimming mechanism that can inform the role mesozooplankton play in biogenic hydrodynamic transport and its impact on marine biogeochemistry.

Global quantification and distribution of antibiotic resistance genes in oceans and seas: Anthropogenic impacts and regional variability

The global spread of antibiotic resistance genes (ARGs) in the marine environment poses a significant threat to public health and natural ecosystems. This study quantified and analysed the distribution and co-occurrence patterns of ARGs in a wide range of oceans and high seas, including the Atlantic, Arctic and Indian Ocean, the Mediterranean Sea and the Persian Gulf. Focusing on beta-lactamases (blaOXA-48, blaCTX-M-1 group, and blaTEM), sulfonamides (sul1) and tetracycline (tetA), our results showed that sul1 was ubiquitous, indicating widespread dissemination. Notably, the Mediterranean Sea exhibited higher levels of multiple ARGs in single samples, suggesting significant anthropogenic impact. Interestingly, the Arctic Ocean, particularly around the Svalbard Islands, also showed the presence of multiple ARGs, highlighting the pervasive occurrence of antibiotic resistance in remote areas. We employed two clustering approaches to explore ARG patterns, primarily focusing on identifying geographic trends and differences in ARG abundance. Additionally, we investigated potential sources of contamination, including proximity to wastewater treatment plants, ports, marine traffic, and currents.These findings clearly demonstrate that antibiotic resistance gene contamination is widespread across diverse marine environments, with significant regional variations. This underscores the urgent need for tailored intervention strategies and global collaboration to mitigate the spread of ARGs and manage their complex dynamics in marine ecosystems.

Adapting management of Pacific salmon to a warming and more crowded ocean

Abstract The North Pacific Ocean is warming and overall Pacific salmon abundance is higher now than at any other time in the past century. This increase in abundance is in large part due to warming-related changes in marine ecosystems at northern latitudes that primarily benefit pink salmon, and industrial-scale hatchery production to support commercial fisheries. A large body of evidence indicates that increasing and more variable ocean temperatures, as well as competition among salmon at sea, are associated with shifts in salmon productivity, body size, and age at maturation. However, these relationships vary by species, location, and time, resulting in increased harvest opportunities in some regions and exacerbated conservation concerns in others. The weight-of-evidence suggests North Pacific salmon nations should, as a minimum, limit further increases in hatchery salmon production until there is a better scientific understanding of hatchery and wild salmon distribution at sea, how they interact, and how the consequences of these interactions are influenced by broader climate and ecosystem conditions. Coordinated research to overcome knowledge gaps and develop strategies to reduce unintended interactions between hatchery and wild salmon could be funded (in part) by a tax placed on industrial-scale hatchery salmon releases. A tax would formalize recognition that there are finite prey resources to support salmon in the ocean and that both prey and wild salmon represent a “common property” whose use should not be without cost to those that seek to benefit from them. We highlight additional approaches salmon nations can take to adapt to changing conditions and suggest that improved communication and collaboration among North Pacific salmon research and management agencies will be key to balancing the benefits and risks of a warming and more crowded ocean.

When the King penguin meets macroplastics: A first case reported in the Crozet archipelago, Southern Indian Ocean

Plastics are one of the major forms of anthropogenic pollution. This waste can affect the individual survival in many species, including seabirds. The Southern Ocean ecosystems are thought to be less affected by this pollution, due to the low human presence and the natural protective barrier provided by southern oceanic fronts. Here, we report the first observation of macroplastic ingestion in two dead King penguins (Aptenodytes patagonicus) in the Crozet archipelago located south of these fronts. There is no evidence that the macroplastic fragments found in their stomach were the direct cause of death. We suggest that they were ingested by being confused with stones they used for food grinding. Although it is difficult to assess the local or distant origin of these macroplastics, efforts to collect waste from sites as remote as the subantarctic islands must become standard practice to ensure that such ingestions do not become commonplace.

Seasonal Surges in Bacterial Diversity along the Coastal Waters of the Eastern Arabian Sea

The upwelling phenomenon plays a vital role within marine ecosystems, transporting essential nutrients from the bottom to the surface and boosting biological productivity. However, the bacterial community structure in upwelling zones along the western coast of India (WCI) is understudied. This research systematically examines bacterial diversity across three seasons—pre-monsoon (PR), monsoon (MN), and post-monsoon (PM)—using next-generation sequencing. Our findings show distinct spatial patterns of bacterial communities in the Arabian Sea and demonstrate that ecological variations influence bacterial distribution in this dynamic environment. During MN, the bacterial community exhibited greater species diversity but lower overall abundance compared to PR and PM. Non-Metric MDS cluster analysis revealed a 78% similarity (at order level) between PR and PM, indicating that MN supports unique bacterial diversity. KEGG analysis showed significant seasonal variations in metabolic functions, with increased functional potential during MN. Additionally, Carbohydrate-Active enZymes (CAZymes) analysis revealed distinct seasonal profiles, among which the GH13 enzymes were the most prevalent glycoside hydrolases during MN, predominantly being sucrose phosphorylase and glucosidase, known for breaking down glucan deposits derived from phytoplankton. The CAZymes profiles supported taxonomic and KEGG pathway findings, reinforcing that microbial communities are seasonally distinct and functionally adapted to changing availability of nutrients.

Gulf Stream mesoscale variabilities drive bottom marine heatwaves in Northwest Atlantic continental margin methane seeps

Methane hydrates on continental margins sequester substantial amounts of methane. Ocean warming often triggers hydrate dissociation, influencing global climate and marine ecosystems. Here we use ocean reanalysis to investigate bottom marine heatwaves affecting methane seeps at the Northwest Atlantic continental margin. These heatwaves are driven by downward displacement of ocean subsurface isopycnals that brings anomalously warm water to the seafloor, which frequently lacked surface expressions. The isopycnal anomalies are generated by the interaction of Gulf Stream mesoscale activity and slope topography, including warm core ring intrusions and impingements at the tail of the Grand Banks. Once generated, the isopycnal anomalies propagate along the slope and affect the seep area via topographic Rossby waves, offering predictability for bottom marine heatwaves. A northward shift and increasing instability of the Gulf Stream has intensified bottom marine heatwaves at the seep area since 2009, and future climate change will likely exacerbate this trend.

Interoperable and scalable echosounder data processing with Echopype

Abstract Echosounders are high-frequency sonar systems used to sense fish and zooplankton underwater. Their deployment on a variety of ocean observing platforms is generating vast amounts of data at an unprecedented speed from the oceans. Efficient and integrative analysis of these data, whether across different echosounder instruments or in combination with other oceanographic datasets, is crucial for understanding marine ecosystem response to the rapidly changing climate. Here we present Echopype, an open-source Python software library designed to address this need. By standardizing data as labeled, multi-dimensional arrays encoded in the widely embraced netCDF data model following a community convention, Echopype enhances the interoperability of echosounder data, making it easier to explore and use. By leveraging scientific Python libraries optimized for distributed computing, Echopype achieves computational scalability, enabling efficient processing in both local and cloud computing environments. Echopype’s modularized package structure further provides a unified framework for expanding support for additional instrument raw data formats and incorporating new analysis functionalities. We plan to continue developing Echopype by supporting and collaborating with the echosounder user community, and envision that the growth of this package will catalyze the integration of echosounder data into broader regional and global ocean observation strategies.

Assessing the Quality of Ship Crew Members in Sewage Pollution Prevention Practices on Marine Environmental Protection: A Case of Dar Es Salaam – Zanzibar Ropax Vessels

The maritime industry is crucial for global trade, but it also significantly impacts the marine environment, particularly through sewage pollution. This study assesses the quality of ship crew members in sewage pollution prevention practices on marine environmental protection, focusing on ROPAX vessels operating between Dar es Salaam and Zanzibar. The stud aims to assess the quality of ship’s crew members in training and education, experience and the number of crew in sewage pollution prevention practices. The study collected data from 80 respondents, whereby both questionnaires were used to collect the data. The data were analyzed by using T-test, Chi-square test, Descriptive statistics and inferential statistics. The study finding revealed that significant deficiencies in awareness and training among crew members regarding MARPOL Annex IV regulations, with many respondents rating their understanding as very low or low. This lack of knowledge, compounded by insufficient formal training programs, hampers the effective implementation of pollution prevention measures. The study recommends a multifaceted approach, including enhanced training, financial support for compliance, and stronger regulatory oversight to improve environmental protection practices. These findings provide crucial insights for policymakers and stakeholders aiming to reduce the environmental impact of the Tanzanian maritime industry and protect marine ecosystem.

Archaeal community from the Northern Hangzhou Bay to the East China Sea: biogeography, ecological processes, and functional potential

IntroductionArchaeal communities play a crucial role in marine ecosystems, yet our understanding of their ecological and functional traits remains incomplete. This study focuses on northern Hangzhou Bay to fill gaps in knowledge regarding the biogeography and functionality of archaeal groups.MethodsWe utilized a high-throughput sequencing dataset based on the 16S rRNA gene to characterize the archaeal community, aiming to identify biogeographic patterns and assess the influence of environmental factors on community structure.ResultsThe predominant phyla identified were Woesearchaeota, Thaumarchaeota, Euryarchaeota, and Crenarchaeota. Archaeal community structure in sediments showed a geographical pattern along the environmental gradient, influenced by factors such as salinity, ammonium, total phosphorus, pH, and total nitrogen content. Network analysis revealed nonrandom co-occurrence patterns, with associations changing along the salinity gradient. Additionally, this study directly proved the existence of dispersal limitation in this strongly connected marine ecological system through null model analyses. Variation in the archaeal community was attributed to both environmental constraints and stochastic processes due to dispersal limitation. Furthermore, our results revealed that the key biogeochemical functions of the archaeal community also exhibited a clear salinity gradient, the functional differences appear to be influenced by salinity, and the critical roles of archaeal diversity were highlighted.DiscussionAll these findings enhance our understanding of microbial ecology and element transformation in estuarine environments. The highlighted roles of archaeal diversity and the influence of environmental factors on community structure and function underscore the complexity of marine microbial ecosystems.

Изменения литоральных популяций рачков-балянусов Semibalanus balanoides (L.) Кольского залива и Восточного Мурмана в период потепления климата в Арктике

Methods for bioindication of early climate impacts in the marine ecosystem are unknown and being developed for the first time. The high rate of changes in the littoral barnacle Semibalanus balanoides (L.) populations is of key importance for bioindication. Mass mortality and significant decrease in the abundance over 1–3 years were observed in estuaries only and mainly associated with an increase of spring floods during the period of ongoing climate warming in the Arctic. The survival of the juveniles appeared in 2023 (up to 8000 sp/m2) fully depends on further climate changes.

Charting the course of Sargassum: Incorporating nonlinear elastic interactions and life cycles in the Maxey–Riley model

Abstract The surge of pelagic Sargassum in the Intra-America Seas, particularly the Caribbean Sea, since the early 2010s has raised significant ecological concerns. This study emphasizes the need for a mechanistic understanding of Sargassum dynamics to elucidate the ecological impacts and uncertainties associated with blooms. By introducing a novel transport model, physical components such as ocean currents and winds are integrated with biological aspects affecting the Sargassum life cycle, including reproduction, grounded in an enhanced Maxey–Riley theory for floating particles. Nonlinear elastic forces among the particles are included to simulate interactions within and among Sargassum rafts. This promotes aggregation, consistent with observations, within oceanic eddies, which facilitate their transport. This cannot be achieved by the so-called leeway approach to transport, which forms the basis of current Sargassum modeling. Using satellite-derived data, the model is validated, outperforming the leeway model. Publicly accessible codes are provided to support further research and ecosystem management efforts. This comprehensive approach is expected to improve predictive capabilities and management strategies regarding Sargassum dynamics in affected regions, thus contributing to a deeper understanding of marine ecosystem dynamics and resilience.

Interannual and seasonal variability of the air–sea CO2 exchange at Utö in the coastal region of the Baltic Sea

Abstract. Oceans alleviate the accumulation of atmospheric CO2 by absorbing approximately a quarter of all anthropogenic emissions. In the deep oceans, carbon uptake is dominated by aquatic phase chemistry, whereas in biologically active coastal seas the marine ecosystem and biogeochemistry play an important role in the carbon uptake. Coastal seas are hotspots of organic and inorganic matter transport between the land and the oceans, and thus they are important for the marine carbon cycling. In this study, we investigate the net air–sea CO2 exchange at the Utö Atmospheric and Marine Research Station, located at the southern edge of the Archipelago Sea within the Baltic Sea, using the data collected during 2017–2021. The air–sea fluxes of CO2 were measured using the eddy covariance technique, supported by the flux parameterization based on the pCO2 and wind speed measurements. During the spring–summer months (April–August), the sea was gaining carbon dioxide from the atmosphere, with the highest monthly sink fluxes typically occurring in May, being −0.26 µmol m−2 s−1 on average. The sea was releasing the CO2 to the atmosphere in September–March, and the highest source fluxes were typically observed in September, being 0.42 µmol m−2 s−1 on average. On an annual basis, the study region was found to be a net source of atmospheric CO2, and on average, the annual net exchange was 27.1 gC m−1 yr−1, which is comparable to the exchange observed in the Gulf of Bothnia, the Baltic Sea. The annual net air–sea CO2 exchanges varied between 18.2 (2018) and 39.1 gC m−1 yr−1 (2017). During the coldest year, 2017, the spring–summer sink fluxes remained low compared to the other years, as a result of relatively high seawater pCO2 in summer, which never fell below 220 µatm during that year. The spring–summer phytoplankton blooms of 2017 were weak, possibly due to the cloudy summer and deeply mixed surface layer, which restrained the photosynthetic fixation of dissolved inorganic carbon in the surface waters. The algal blooms in spring–summer 2018 and the consequent pCO2 drawdown were strong, fueled by high pre-spring nutrient concentrations. The systematic positive annual CO2 balances suggest that our coastal study site is affected by carbon flows originating from elsewhere, possibly as organic carbon, which is remineralized and released to the atmosphere as CO2. This coastal source of CO2 fueled by the organic matter originating probably from land ecosystems stresses the importance of understanding the carbon cycling in the land–sea continuum.

Viromes vs. mixed community metagenomes: choice of method dictates interpretation of viral community ecology

BackgroundViruses, the majority of which are uncultivated, are among the most abundant biological entities on Earth. From altering microbial physiology to driving community dynamics, viruses are fundamental members of microbiomes. While the number of studies leveraging viral metagenomics (viromics) for studying uncultivated viruses is growing, standards for viromics research are lacking. Viromics can utilize computational discovery of viruses from total metagenomes of all community members (hereafter metagenomes) or use physical separation of virus-specific fractions (hereafter viromes). However, differences in the recovery and interpretation of viruses from metagenomes and viromes obtained from the same samples remain understudied.ResultsHere, we compare viral communities from paired viromes and metagenomes obtained from 60 diverse samples across human gut, soil, freshwater, and marine ecosystems. Overall, viral communities obtained from viromes had greater species richness and total viral genome abundances than those obtained from metagenomes, although there were some exceptions. Despite this, metagenomes still contained many viral genomes not detected in viromes. We also found notable differences in the predicted lytic state of viruses detected in viromes vs metagenomes at the time of sequencing. Other forms of variation observed include genome presence/absence, genome quality, and encoded protein content between viromes and metagenomes, but the magnitude of these differences varied by environment.ConclusionsOverall, our results show that the choice of method can lead to differing interpretations of viral community ecology. We suggest that the choice of whether to target a metagenome or virome to study viral communities should be dependent on the environmental context and ecological questions being asked. However, our overall recommendation to researchers investigating viral ecology and evolution is to pair both approaches to maximize their respective benefits.ADm-mTTAXM3aVZwCyoroCBVideo

Toxicity of Nitrite to Juvenile Sunray Surf Clam (Mactra chinensis Philippi)

Nitrite is a common pollutant in marine environments and can cause mortality in crustaceans and bivalves. The purpose of the current study is to understand nitrate’s toxicity to juvenile clams due to its potential impact on aquaculture and marine ecosystems. Juvenile sunray surf clams (Mactra chinensis Philippi) (1.00 ± 0.10 cm shell length, 0.75 ± 0.04 cm shell height) were exposed to varying concentrations of nitrite for 96 h and 20 days, respectively. The LC50 for survival at 96 h was 37 mg/L NO2-N. Histological evaluations were made on juvenile clams exposed at 30 mg/L after 20 d of exposure. Epithelial cells and digestive diverticulum are the best sub-lethal effect indicators. Shell length and antioxidant enzyme activities were measured at the beginning of the experiment and then observed 10 and 20 days after exposure. A logarithmic relationship was obtained between the relative growth rate (based on the shell length) of juvenile M. chinensis and the nitrite concentration. Compared to the control, activity suppression of superoxide dismutase and catalase activity was detected from the concentration of 1 mg/L NO2-N. It is recommended that nitrite concentrations remain below 1 mg/L to prevent stress during the early developmental stages of clams.

Bioactives from marine resources as natural health products: A review.

The oceans are a rich source of a myriad of structurally different and unique natural products that are mainly found in invertebrates with potential applications in different disciplines. Microbial infection and cancer are the leading causes of death worldwide. Discovery of new sources of therapy for microbial infections is an urgent requirement due to the emergence of pathogenic microorganisms that are resistant to existing therapies. Marine bioactives have demonstrated to be promising sources for the discovery and development of novel antimicrobial and anticancer compounds. Several marine compounds are confirmed to have antibacterial effects and most marine-based antifungal compounds are cytotoxic. Numerous antitumor marine natural products, derived mainly from sponges or molluscs, and also bryozoans and cyanobacteria, exhibit potent antimitotic activity. In addition, marine biodiversity offers some possible leads or new drugs to treat human immunodeficiency virus (HIV). A majority of marine derived drugs are currently in clinical trials or under preclinical evaluation. Furthermore, marine-based drugs, approved by the US Food and Drug Administration (FDA) are available in the market. This review summarizes the sources, mechanisms of action and potential utilization of marine natural products such as peptides, alkaloids, polyketides, polyphenols, terpenoids and sterols as antifungal, antibacterial, antiviral, and anticancer compounds. Significance Statement Utilization of marine bioactives as natural health products leads to crucial advancement in providing dietary supplements, nutraceuticals, functional foods and pharmaceuticals. Their myriad of application promotes health and plays a role in disease risk reduction. Therapeutic potential of potent compounds from marine organisms and use of their bioactives have promising medicinal value for preventing ailments and advancing pharmaceutical and nutraceutical industries. Their utilization benefits human health globally and contributes to the conservation of marine ecosystem in a transformative / sustainable approach.