Adjacent Waters Research Articles

Mercury (Hg) in the "Skin" of the Ocean: Dissolved Gaseous Hg, Total Hg, and Hg Redox Chemistry in Sea Surface Microlayer and Implication for Air-Sea Hg Exchange.

The sea surface microlayer (SML) is the uppermost ∼1000 μm of the surface of the ocean. With distinct physicochemical properties and position relative to the adjacent subsurface waters (SSWs), the ubiquitous distribution and high dynamics of the SML greatly regulate the global air-sea gas exchange and biogeochemistry. Mercury (Hg) redox chemistry in surface seawaters and air-sea exchange of gaseous Hg (mainly Hg(0)) fundamentally control the global oceanic Hg cycle. However, the occurrence and transformation of Hg in the SML have been poorly quantified. Here we optimize the traditional SML sampling system to make it more suitable for dissolved gaseous Hg (DGM, mainly Hg(0)) sampling. We then assess the temporal and spatial variability of DGM, total Hg, dissolved organic carbon (DOC), and Hg redox chemistry in the SML and SSWs of diverse marine environments. Our data suggest a general DGM, total Hg, and DOC enrichment in the SML relative to the SSWs but with complex variability in time and space. The incubation experiments further reveal the complex characteristics of Hg redox chemistry between the SML and SSWs. We discuss important implications of the SML Hg cycle on air-sea Hg exchange and suggest wider investigations of the SML Hg cycle in the global hydrosphere.

Ecological distribution patterns in Chinese seas and adjacent waters: Marine ecological zones

To provide a natural foundation and regionalization framework for ecological monitoring, assessment, and mapping to support ecosystem-based management practices of natural resources, three levels of ecological zones were classified in Chinese seas and adjacent waters using top-down and step wise nesting. At the largest spatial scale, the Chinese seas and adjacent waters were classified into three first-level ecological zones according to latitudinal zones and geographic profiles. To incorporate the dimensionalities and mobility of the seas, 22 second-level ecological zones were classified according to changes in water depth and the distribution of large water masses, and 53 third-level ecological zones were further delineated according to the type of geomorphology and the distribution of water masses and currents. This study identifies dominant factors at different spatiotemporal scales and defines the physical geographical patterns and ecological characteristics in Chinese seas and adjacent waters in a readily understood manner and fills the gap in research on ecological zoning in China.

Enhanced impact of prolonged MHWs on satellite-observed chlorophyll in the South China Sea

Marine heatwaves (MHWs) are period of extreme ocean temperatures that can last from a few days to several years. The increasing frequency and intensity of MHWs have devastating impacts on marine ecosystems. This study explores the characteristics of MHWs from 1982 to 2021 and their effects on chlorophyll (Chl) from 1998 to 2021 in the South China Sea (SCS), utilizing satellite data and reanalysis products. MHWs were classified into short-duration MHWs (SMHWs) and long-duration MHWs (LMHWs) based on their duration to analyze their effects. High-intensity and frequent MHWs were observed in the coastal regions of China, the western SCS (WSCS, average depth more than 200 m), and southwest of the Luzon Strait (LS, average depth more than 200 m). MHWs have increased by 14 days (R2 = 0.42, p < 0.01) and 0.99 times (R2 = 0.36, p < 0.01) per decade over the past four decades. The per-decade rate of increase is 44 % of the average MHWs days, and 36 % of the frequency in entire SCS.LMHWs contributed the most to this increase at a rate of 6.5 days (R2 = 0.43, p < 0.01) and 0.25 times (R2 = 0.45, p < 0.01) per decade. The trend of MHWs in the Pearl River estuary (PRE, On the coastal continental shelf, average depth <200 m) is noteworthy for cause for concern, increasing by 19 days and 1.4 times per decade.During SMHWs, the Chl response was relatively insignificant, with roughly 3 % negative anomalies across the entire SCS. However, LMHWs had a more profound impact on Chl,which decliend 8 % over the SCS, especially in the WSCS, PRE, and southwest of LS. During summer in the WSCS and winter southwest of LS, the negative anomalies of Chl varied between 20 % and 40 % of its daily climatology for each grid. In contrast, a noteworthy positive Chl response was observed in the PRE and adjacent waters during summer. The duration and intensity of MHWs in these regions affected Chl, and the suppression of Chl was more prominent as the intensity and duration increased, except in the PRE, where MHWs promoted Chl during both spring and summer. We identified various mechanisms by which MHWs impacted Chl in these regions, including weakened upwelling and eddies in the WSCS, changes in plume distribution along the PRE, and shallow mixed layer and weakened cyclonic circulation in the LS during winter. Our study underscores the need for immediate conservation measures to mitigate the effects of MHWs on marine ecosystems, particularly in the PRE and adjacent regions where harmful algal blooms (HABs) are a frequent and ongoing threat.

Evolutionary history and seascape genomics of Harbour porpoises (Phocoena phocoena) across environmental gradients in the North Atlantic and adjacent waters.

The Harbour porpoise (Phocoena phocoena) is a highly mobile cetacean species primarily occurring in coastal and shelf waters across the Northern hemisphere. It inhabits heterogeneous seascapes broadly varying in salinity and temperature. Here, we produced 74 whole genomes at intermediate coverage to study Harbour porpoise's evolutionary history and investigate the role of local adaptation in the diversification into subspecies and populations. We identified ~6 million high quality SNPs sampled at eight localities across the North Atlantic and adjacent waters, which we used for population structure, demographic and genotype-environment association analyses. Our results suggest a genetic differentiation between three subspecies (P.p. relicta, P.p. phocoena and P.p. meridionalis), and three distinct populations within P.p. phocoena: Atlantic, Belt Sea and Proper Baltic Sea. Effective population size and Tajima's D suggest population contraction in Black Sea and Iberian porpoises, but expansion in the P.p. phocoena populations. Phylogenetic trees indicate post-glacial colonization from a southern refugium. Genotype-environment association analysis identified salinity as major driver in genomic variation and we identified candidate genes putatively underlying adaptation to different salinity. Our study highlights the value of whole genome resequencing to unravel subtle population structure in highly mobile species, shows how strong environmental gradients and local adaptation may lead to population differentiation, and how neutral and adaptive markers can give different perspectives on population subdivision. The results have great conservation implications as we found inbreeding and low genetic diversity in the endangered Black Sea subspecies and identified the critically endangered Proper Baltic Sea porpoises as a separate population.

Distribution pattern of macrobenthic assemblages along a salinity gradient in the Hangzhou Bay and its adjacent waters

Distribution pattern of macrobenthic assemblages along a salinity gradient in the Hangzhou Bay and its adjacent waters

BIODIVERSITY AND BIORESOURCES OF DEEP-SEA ECOSYSTEMS OF THE NORTHWESTERN PACIFIC

Modern problems of the investigation of marine biodiversity and bio-resources and their inventory in the deep-sea of the World Ocean are considered. The discussion of these problems is also based on the data of aseries of deep-water marine expeditions of the National Scientific Center of Marine Biology of the Far Eastern Branch of the Russian Academy of Sciences (NSCMB FEB RAS) in the deepest areas of the Far Eastern Seas and adjacent waters of the North-West Pacific. New results of a series of the deep-sea expeditions within the special RAS Project “Fundamental problems of investigation and conservation of the deep-sea ecosystems in the potentially ore-reach areas in the North-West Pacific” are briefly introduced and discussed (project of RAS № 3.1902.21.0012). Several “unique” deep-sea ecosystems found in the ore bearing sites and the active fishing areas in the North-West Pacific are described. Some safety opportunities for these “unique” ecosystems and possible limitations in the use of dangerous mining and fishing techniques disturbing deep-sea landscapes are considered, including various conservation statuses.

Addressing Phosphorus Waste in Open Flow Freshwater Fish Farms: Challenges and Solutions

Legislation and interest exists to protect and restore freshwater and marine ecosystems from the environmental impact of aquaculture. However, aquaculture-induced eutrophication remains a major environmental concern. Water soluble phosphorus, uneaten feed, feces, and metabolic waste from farmed fish increase phosphorus concentrations in adjacent waters. In open freshwater fish farms, in particular, the effects can be more immediate, as excess phosphorus is introduced directly into ecosystems. Several intestinal enzymes, transporters, and regulating factors have been implicated in farmed fish dietary phosphorus retention. For example, alkaline phosphatase and other transporters aid in the absorption of phosphorus in the anterior intestine, while pH, calcium, and vitamin D influence these enzymes and transporters. This process may also be influenced by intestinal morphology and the gut microbiome. To reduce phosphorus pollution from open flow fish farms, a thorough understanding of the processes that affect nutrient retention and absorption, as well as the impact of dietary factors, anti-nutritional substances, and intestinal morphology, is required. Aquaculture can be made more sustainable by reducing phosphorus release. This can be achieved by optimizing feed composition, adding functional feed ingredients, managing gut health, and treating effluent aquaculture waters with bioremediation and absorbing materials. Anti-nutritional factors can be mitigated through processing and through the use of functional feed additives. Addressing these issues will reduce aquaculture’s environmental impact, ensuring aquatic ecosystem health and global food security. In addition, treating effluent aquaculture waters with bioremediation and absorbing materials can remove phosphorus from the water, preventing it from entering the environment. This can further reduce the environmental impact of aquaculture and help to ensure the sustainability of this sector.

PRESENCE OF METACERCARIAE OF Opisthorchis sp. BLANCHARD, 1895 (TREMATODA: OPISTHORCHIIDAE) IN NEW HOST Macrobrachium amazonicum (HELLER, 1862), FROM THE NORTHERN BRAZIL: AN EMERGING RISK TO HUMANS BY THE SHRIMP CONSUMPTION

Herein, we report the first observation of the metacercaria Opisthorchis sp. Blanchard, 1895 recovered from a new intermediate host Macrobrachium amazonicum (Heller, 1862), an important food resource from northern Brazil, emphasising the risk of contamination from inappropriate human consumption. The shrimp specimens of M. amazonicum were collected during June 2023, using a local trap called matapi in the Guamá River (01°27’54.2”S; 048°26’02.6”W), which supplies the city of Belém, showing a characteristic of an eutrophicated river. The collected specimens were sexed, measured, weighted and dissected in the carapace region, to observe the presence of parasites in gills, hepatopancreas and gonads. We observed 56 specimens of M. amazonicum (20 males, 32 females and 4 ovigerous females), of which thirteen individuals (23.21% of total sampled) showed encysted metacercariae of Opisthorchis sp. only in gonadal tissues, with high preference in females (66.6%), when compared with males (33.4%). The observation of metacercaria in Amazon river prawn is a risk to human health, due to the parasite's life cycle being completed in humans, leading to several health problems such as hepatic and biliary degradation, diarrhoea, vomiting and respiratory problems. Additionally, the eutrophication process observed in the Guamá River may favour parasite proliferation, and dissemination to other hosts and regions, possibly increasing the cases of people infected with parasites in Belém metropolitan area. Based on that, this work is an alert to the authorities for the risk of contamination of the population due to inadequate consumption of (molluscs, crustaceans and fishes) from the eutrophic waters of the Guamá River and adjacent waters.

Five Years Measuring the Muck: Evaluating Interannual Variability of Nutrient Loads From Tidal Flooding

Due to sea level rise, tidal flooding is now common in low-lying coastal systems around the world. Yet, the contribution of tidal flooding to non-point source nutrient loads and their impact on the quality of adjacent waters remains poorly constrained. Here, we quantified dissolved nutrient loading and Enterococcus abundance during annual autumnal king tides (i.e., perigean spring tides), between 2017 and 2021, in a sub-watershed of the lower Chesapeake Bay. To calculate nutrient loading from tidal flooding, we used geospatial inundation depths from a street-level hydrodynamic model to estimate floodwater volumes during each of the five sampling events and the difference between nutrient concentrations in floodwater and pre-flood measurements. Results showed that dissolved nutrient concentrations were higher in floodwaters than in estuarine waters and resulted in dissolved nitrogen and phosphorus loads that reached 58.4 × 103 kg and 14.4 × 103 kg, respectively. We compared our load estimates to the tributary-specific total and land-based federal allocations (i.e., total maximum daily loads (TMDL)) for total nitrogen (TN) and total phosphorus (TP). Even the more conservative calculations indicate that inputs of dissolved nutrients during a single tidal flooding event can exceed 100% of the annual load allocation. Additionally, more than 80% of the floodwater samples collected each year showed Enterococcus abundance that exceeded the threshold for recreational water use in Virginia (104 MPN 100 ml−1). Failing to account for non-point source loading of nutrients and contaminants from tidal flooding as sea level rises could result in worsening eutrophication and deterioration of coastal economies and the health of coastal communities around the world.

Characterization of suspended sand concentrations in the Yangtze River Estuary and adjacent waters

IntroductionThe study on the distribution characteristics of suspended sediment concentration (SSC) in estuaries is an important subject in the study of estuaries and coasts, which has important theoretical significance and practical value.MethodsIn order to fully understand the characteristics of SSC in the Yangtze River Estuary and its adjacent waters, this paper uses fixed vertical observation data and navigation type large area observation data as data sources to analyze the distribution characteristics of SSC in the Yangtze River Estuary and its adjacent waters under different tidal current states and its vertical profile characteristics. It discusses the impact of tidal current velocity on SSC and the changes of SSC in the Yangtze River Estuary and its adjacent waters from 2018 to 2020. And the applicability of the Rouse and Soulsby formulas in the Yangtze River Estuary and its adjacent waters was verified.ResultsIt was found that the Rouse and Soulsby models have high applicability in the study area, and the prediction accuracy based on the Li’s Soulsby model is higher. This study provides effective support for carrying out marine forecasting, analysis and evaluation, and provides theoretical basis for carrying out analysis of the current situation of estuarine mudflat resources and prediction of the evolution trend. It plays an important role in scientific and comprehensive research and management of mudflat resources in Shanghai.DiscussionHowever, this study only explored the characteristic patterns of SSC in the Yangtze River Estuary and its adjacent waters based on field observations, but SSC is a more complex water environment parameter that is influenced by a variety of factors. The effects of salinity, temperature and wind speed should be considered in subsequent studies.

FIRST REPORT IN CANADA OF CERATONOVA GASTEROSTEA (CNIDARIA: MYXOZOA) IN THREESPINE STICKLEBACK GASTEROSTEUS ACULEATUS FROM THE FRASER RIVER, BRITISH COLUMBIA.

A survey of threespine stickleback (Gasterosteus aculeatus L.) and juvenile Chinook salmon (Oncorhynchus tshawytscha (Walbaum)) from the lower Fraser River, British Columbia, Canada and adjacent marine waters was conducted for the presence of myxozoan parasites of the genus Ceratonova Atkinson, Foott, and Bartholomew, 2014 (Bivalvulida, Ceratomyxidae). Quantitative polymerase chain reaction (PCR; small subunit ribosomal RNA gene) combined with conventional PCR and sequencing (ribosomal internal transcribed spacer region 1) detected Ceratonova gasterostea Atkinson, Foott, and Bartholomew, 2014 in 89 of 269 (33.1%) sticklebacks from the Fraser River and in 1 of 51 (2%) from Howe Sound. In contrast, Ceratonova shasta (Atkinson, Foott, and Bartholomew, 2014) was detected in 2 of 26 (7.7%) Chinook salmon from the Fraser River. Reciprocal infections were not detected. Light microscopic examination of the stickleback intestine revealed the presence of an intense infection with large numbers of pseudoplasmodia which interacted with enterocytes through pseudopodia-like projections. Myxospores with characteristic elongate valve cells were visible within mature pseudoplasmodia and free in the intestinal lumen. This is the first report of C. gasterostea in Canada.

A dataset of zooplankton occurrence, abundance, and biomass in the Far East seas and adjacent Pacific Ocean waters.

Planktonic animals drifting or floating in the sea have small body sizes and weights from hundreds to thousands of milligrams, and are primarily the food for other zooplankton and macrofauna: fish, cephalopods, seabirds and marine mammals, and also the larval pool of many benthic invertebrates. This paper describes a unique dataset of zooplankton collected from 1984 to 2013 in the North Pacific (the Bering Sea, Sea of Okhotsk, Sea of Japan and adjacent Pacific Ocean waters), one of the most productive and economically important regions of the world's oceans using a Juday net made of kapron sieve No. 49 (0.168 mm mesh) with a 0.1 m2 opening. The information in this dataset has already been used to quantify the inventory of marine biological resources and assess the waters of the Russian Far Eastern seas and adjacent Pacific Ocean. In 2016, five tabular reference books were printed in Russian in limited numbers containing the species composition, occurrence (number and percentage of samples), abundance and biomass (in individuals per cubic meter, milligrams per cubic meter) of zooplankton in the surveyed area. The data are grouped by species, developmental stages, size fractions (animal length of 0.6-1.2 mm "fine/small," 1.2-3.2 mm "medium" and >3.2 mm "large"), standard regions (their total area is more than 6 million km2 ), vertical layers of water, light and dark time of the day, four seasons of the year and multiyear periods, in which there were considerable changes in the biota of the region caused by global climate and oceanographic factors. This information has recently been verified, corrected, translated into English, transformed from text to digital format, and supplemented by GIS with maps of the standard regions by which data were aggregated using morphometric parameters (volume of water in cubic kilometers in the region, in its epipelagic 0-200 m, and upper epipelagic 0-50 m water layers, occupied area in square kilometers, longitude and latitude of their centroids in decimal degrees) to increase their availability to the scientific community worldwide. The data enable the evaluation of the total plankton stock of the Russian Far Eastern seas in the North Pacific (in trillions of specimens and thousands of tons), recalculate the volumetric characteristics of density into areal characteristics (in billions of specimens per square kilometer or tons per square kilometer), and, using previously published tables on calorific value and chemical composition of zooplankton, obtain their energy characteristics. Such data are crucial for the proper management of marine resources, aquaculture development, nature conservation, and the assessment of the anthropogenic impact on nature. The presented metadata provide a detailed description of how this unique dataset was created, sources and volume of gathered information, its benefits and drawbacks, some results on the quantitative inventory of marine biological resources and assessment of waters in the North Pacific, and future prospects for the use of this type of dataset in applied and fundamental research. There are no copyright restrictions on the data; please cite this data paper when the data are used in publications.

An Analytic Model for Identifying Real-Time Anchorage Collision Risk Based on AIS Data

With the increasing volume of ship traffic, maritime traffic safety is facing a great challenge because the traffic in port becomes more and more crowded and complicated, which will make ship collisions more likely to happen. As a special water area of the port, the anchorage is also threatened by collision risk all the time. For accurately assessing the collision risk in anchorage and its adjacent waters in real time, this paper proposed an analytic model based on Automatic Identification System (AIS) data. The proposed anchorage collision risk model was established in microscopic, macroscopic, and complexity aspects, which considered ship relative motion, anchorage characteristics, and ship traffic complexity, respectively. For validation, the AIS data of the anchorages near the Shandong Peninsular were used to carry out a series of experiments. The results show that the proposed model can identify the anchorage collision risk effectively and has an advantage in dealing with complicated scenarios. The proposed anchorage collision risk model can help maritime surveillance better monitor and organize the ship traffic near the port and provide mariners with a reference about the collision risk situation of the anchorage on their route, which are important to improving maritime traffic safety.

Presence of Perfluoroalkyl Substances in Landfill Adjacent Surface Waters in North Carolina.

Landfills pose an important public health risk, especially in historically disenfranchised communities that are disproportionately sited for landfills and in rural areas where private wells may be impacted. Landfills are major sources of perfluoroalkyl substances (PFAS) that migrate into the surrounding environment. This study characterized PFAS in surface waters adjacent to two landfills, one in Sampson County (SC) and one in Orange County (OC) in North Carolina. In addition to municipal solid waste and construction and demolition waste, the landfill in SC accepts industrial sludge from a chemical plant that produces proprietary PFAS. Over four months, 35 surface water samples were collected at upstream, landfill-adjacent, and downstream/downgradient sites. Thirty-four PFAS were analyzed using liquid chromatography with tandem mass spectroscopy. Of those, six novel and six legacy PFAS were detected. Legacy PFAS were detected in surface water near both landfills, with the highest concentrations adjacent to the landfill. Novel PFAS were only detected in surface water near the SC landfill and showed the highest concentrations adjacent to the landfill, indicating offsite migration of PFAS. These findings support the need for more comprehensive and frequent monitoring of groundwater and surface water wells near landfills and stricter regulation regarding the landfilling of industrial materials.

Sulfate-rich spring seeps and seasonal formation of terraced, crystalline mirabilite mounds along the shores of Great Salt Lake, Utah: Hydrologic and chemical expression during declining lake elevation

As Great Salt Lake (GSL) elevation declined below ∼1278.6 m (4195 ft) beginning in the fall of 2019, crystalline mounds formed on the southeastern shore, near Great Salt Lake State Park, Utah. Soon after, several more mound complexes were discovered on nearby Antelope Island. Recent historic low lake levels permitted sulfate-saturated spring brines to emerge on the exposed shoreline. When the spring waters encountered cold winter air, sodium sulfate precipitated in the form of the mineral mirabilite (Na2SO4·10H2O). Mirabilite-saturated spring waters pool in shallow sediment-collapse depressions or, with sufficient hydraulic head, precipitate subaerial crystalline spring terraced mounds. The mounds are composed of clear, bladed, and tabular mirabilite crystals (1 to 10 cm in length; 1 to 5 cm in width) that form mini pools and rimstone dams due to cascading spring water flow. The waters have elavated μM concentrations of sulfide, an oxidation-reduction potential (ORP) of −250 mV, pH of 7, densities of 1.103–1.1169 g/cm3, and temperatures of 10°–15 °C, as compared to nearby lake waters that had undetectable sulfide, an ORP of 12 mV, pH of 8.2, density of 1.0872 g/cm3, and temperatures of 0°–3 °C. Green algae and probable sulfide oxidizing bacteria thrive in the spring waters and some are occluded within the mirabilite matrix and fluid inclusions. Sulfur δ34S and oxygen δ18O isotopes of brine and mirabilite sulfate are enriched +18.8–20.41‰ and + 12.2–14.5‰, respectively, indicating groundwater and mirabilite are in equilibrium for oxygen. Brine sulfide is heavily fractionated (δ 34S of ∼ − 30 ‰) relative to sulfate, indicating active sulfate reduction in subsurface aquifers that feed the spring seeps and which is consistent with higher HS− concentrations relative to adjacent lake waters. The recognition of such biosignatures retained in mirabilite provides further insights for the preservation potential of biological material in extraterrestrial sulfate minerals.Today, Gilbert Bay (south arm of GSL) is undersaturated with respect to mirabilite. However, pre-earthen causeway historical reports (prior to 1959) indicate mirabilite precipitated in the south arm during the winter and through wave action accumulated along the leeward southeastern oolitic shore (similar to current processes occurring in the hypersaline Gunnison Bay, the north arm of GSL). Upon solar irradiance in the spring, the shoreline mirabilite dissolved and reprecipitated in the shallow subsurface (<1 m) as an ooid cement. We hypothesize that this subsurface layer of mirabilite is the source for active lake margin sodium sulfate-saturated spring brines. The emergence and surface exposure of the brines and associated chemical sediments are an additional contributing solute source that may increase GSL salinity during lake level decline more than evaporation alone.

Silicon composition and stoichiometric ratios with other nutrients in the lower Minjiang River, Southeast China.

Over the past decades, rivers have delivered imbalanced nutrient loads to coastal marine ecosystems due to human activities, which leads to serious regional or global eutrophication problems. The Minjiang River is heavily influenced by human activities. To understand the changing characteristics of nutrient transport ratios in the Minjiang River waters, we measured the seasonal variations of carbon, nitrogen, phosphorus and silicon nutrients in the lower surface waters of the Minjiang River between July 2019 and July 2020. The results showed that the annual average contents of dissolved silicon (DSi), lithogenic silicon (LSi) and biogenic silicon (BSi) in the surface waters of the lower Minjiang River were 5.30, 4.58 and 2.37 mg·L-1, respectively. There were large seasonal differences among these parameters, with higher content of DSi than LSi and BSi in summer, higher content of DSi than BSi and LSi in autumn and higher content of LSi than DSi and BSi in winter. The proportions of DSi in total silicon tended to decrease gradually from land to sea, while the proportion of BSi was on the contrary. In term of stoichiometric ratios, the Minjiang River mostly presented carbon or phosphorus limitation and was unlimited by silicon or nitrogen. About 1.03×1010 mol DSi and 0.46 ×1010 mol BSi were delivered via the Minjiang River to the ocean yearly, showing a decreasing trend year by year. Based on the data in recent years, the nutrient loads of carbon, nitrogen, and phosphorus transported by Minjiang River showed an increasing trend. The imbalanced nutrient loads may lead to changes in the structure and function of the river, estuary, and offshore ecosystems. The study of nutrient stoichiometric ratios can provide a theoretical basis for solving the problems in structural balance of nutrients and eutrophication in Minjiang River estuary and adjacent marine waters.

Clutch fullness index as an early indicator of overexploitation of the Southern King Crab: Implications for fisheries management

Southern king crab is a high-value fishing resource commercially exploited in the Argentine Patagonia (south 44° S) since 2004. The ovigerous mass size of females, estimated as the clutch fullness index (CFI), has been used as a proxy for qualitative fecundity and an indicator of population health. In 2015, the use of CFI allowed the early detection of signs of overexploitation of the Southern king crab. This study aimed to assess temporal variations in the CFI in relation to fishing effort and management measures. Data were collected from commercial vessels between January and May from 2012 to 2020 in the Central Patagonian Sector (comprising the San Jorge gulf and adjacent shelf waters, 43°30′- 48°S). The Correspondence Analysis and hierarchical cluster analysis showed that the CFI varied among years. The variation of the CFI was opposite to the fishing effort. The CFI decreased between 2015 and 2017 (from 80% of females with 100% CFI in 2014 to 43% in 2017), and increased since 2018 (from 57% in 2018 to 78% in 2020). This is probably due to the implementation of two new management measures (extended closed season and the regulation of an annual catch quota). Two indicators of L. santolla reproductive status are proposed based on empirical data. The first one is the proportion of non-ovigerous mature females during the incubation period, which could reflect a male shortage during the mating period must not exceed 10% and the second one is the proportion of females with a complete clutch must be greater than 40%. The CFI variations and the proposed indicators can constitute an alternative to the crabs traditional management.

Sustainability Perspective of Minjiang Estuary Coastal Fisheries Management—Estimation of Fish Richness

Species richness is the most basic concept of diversity and is crucial to biodiversity conservation and sustainable fisheries. To understand the fish species richness of the Minjiang Estuary and its adjacent waters, eight documents and surveyed data were collected and compared from 1990–2021. To obtain suitable analysis data, the content of the data was compared and evaluated. Explore the suitability of data based on several criteria. Among them, the bottom trawling survey carried out in 2006–2007, and non-parametric estimation methods such as Chao 2, Jackknife 1, Jackknife 2 and Bootstrap were used to estimate the fish species richness. The results of this case show that a total of 153 species of fish were caught in the trawling survey in the fourth quarter, belonging to 14 orders, 57 families and 101 genera. The 2006–2007 cruise is more complete for studying species richness. The Estimable expectations of fish species richness are: 250 (Chao 2), 204 (Jackknief 1), 241 (Jackknief 2) and 174 (Bootstrap). The number of fish species was significantly higher in summer and autumn than winter and spring. To manage fishery resources and sustainability in the sea area of Fujian Province, biological information and stock assessment are required. This meaningful information, especially for endemic and economically important species such as can set a baseline. Once species change exceeds the baseline range, it provides decision-making basis for marine biodiversity conservation and fisheries management.

Marine Heatwave Characteristics in the Makassar Strait and Its Surrounding Waters

This study aimed to investigate the characteristics of marine heatwaves (MHWs) in the Makassar Strait and adjacent waters (MSAW) using the Optimum Interpolation Sea Surface Temperature (OISSTv2) dataset from 1982 to 2021. The analysis revealed a significant positive trend in the frequency and duration of MHWs, while the mean and maximum intensities displayed a negative trend over the 40-year period. By examining two different phases of the Pacific Decadal Oscillation (PDO), it was observed that the cold phase (more frequent La Niña events than El Niño) had higher MHW frequency and duration, whereas the warm phase (more frequent El Niño events than La Niña) exhibited higher mean and maximum intensities. Moreover, the occurrence of high-intensity MHWs was associated with weakened winds, the decaying phase of El Niño and positive Indian Ocean Dipole (IOD), and high net surface heat flux (NSHF). An intriguing finding emerged, indicating a notable lag of 7–9 months (10 months) between El Niño (positive IOD) events and the emergence of high-intensity MHWs. This lag suggests that MHWs are more likely to manifest during the transition towards La Niña and negative IOD conditions. Additionally, the study highlighted a stronger correlation between the El Niño–Southern Oscillation and MHW intensity in the MSAW compared to the IOD. Furthermore, the different intensities of MHWs were found to be linked to NSHF, which exhibited higher values during the warm phase of the PDO compared to the cold phase.

Non-Point Sources (Septic Tanks) of Surface Water Nutrient Pollution: A Review and a Study of Taylor Creek, Okeechobee County, Florida

This study investigated the impact of high-density septic systems (aka Onsite Sewerage and Disposal Systems, OSTDS) along the canals located in the communities of the lower Taylor Creek area on water quality at the northern periphery of Lake Okeechobee. Using sucralose as an anthropogenic tracer, we investigated the septic derived non-point sourcing of nutrients which feed harmful algal (cyanobacterial) blooms (HABs) in Lake Okeechobee and adjacent waters. &#x0D; &#x0D; The subdivisions investigated were Treasure Island (TI) and Taylor Creek Isles (TCI) located to the east and west of Taylor Creek. TI homes are all on septic tanks whereas TCI is serviced by a municipal vacuum sewerage system.&#x0D; &#x0D; TI canals had 5.3 times the mean concentration of sucralose relative to TCI canals. On a yearly basis, the Treasure Island sites away from Taylor Creek had 2.25 times the total phosphorus and 1.20 times the total nitrogen compared to the Taylor Creek isles sites. An extensive literature review of non-point pollution is included.