Life-history studies on infrapopulations of Mazocraes alosae (Monogenea) parasitising Alosa immaculata (Actinopterygii) in the northern Black and Azov Seas.

The life-history of Mazocraes alosae Hermann, 1782 on one of its hosts, the Pontic shad Alosa immaculata Bennett, is described for the first time. This anadromous fish, which occurs off the coast of the Crimea and migrates from the Black Sea to the Sea of Azov and into the River Don for spawning, was studied throughout its migration and during all seasons. It is demonstrated that the period of reproduction of this monogenean is significantly longer than that reported for the population in the Caspian Sea, lasting from April to November with a peak in April-May, and continues both in the sea and the river. Experiments showed that water salinity does not limit the development of the eggs or the hatching of the oncomiracidia. Our data reveal that the abundance of M. alosae is not determined by the size or sex of mature fish and that shad of less than two years old can also be infected with this monogenean, although less frequently than older fish. The direction of the migration of A. immaculata, either from the Black Sea to the Sea of Azov and into the rivers or in the opposite direction, does not influence the number of monogeneans present on the host. The main factor affecting the dynamics of the abundance of this monogenean is season, and, as has been indicated previously in the Caspian Sea basin, there is a synchronisation between the parasite's life-history and both the host's spawning behaviour and the duration of its migration.

Biogeography and ecology of Ostracoda in the U.S. northern Bering, Chukchi, and Beaufort Seas.

Ostracoda (bivalved Crustacea) comprise a significant part of the benthic meiofauna in the Pacific-Arctic region, including more than 50 species, many with identifiable ecological tolerances. These species hold potential as useful indicators of past and future ecosystem changes. In this study, we examined benthic ostracodes from nearly 300 surface sediment samples, >34,000 specimens, from three regions-the northern Bering, Chukchi and Beaufort Seas-to establish species' ecology and distribution. Samples were collected during various sampling programs from 1970 through 2018 on the continental shelves at 20 to ~100m water depth. Ordination analyses using species' relative frequencies identified six species, Normanicythere leioderma, Sarsicytheridea bradii, Paracyprideis pseudopunctillata, Semicytherura complanata, Schizocythere ikeyai, and Munseyella mananensis, as having diagnostic habitat ranges in bottom water temperatures, salinities, sediment substrates and/or food sources. Species relative abundances and distributions can be used to infer past bottom environmental conditions in sediment archives for paleo-reconstructions and to characterize potential changes in Pacific-Arctic ecosystems in future sampling studies. Statistical analyses further showed ostracode assemblages grouped by the summer water masses influencing the area. Offshore-to-nearshore transects of samples across different water masses showed that complex water mass characteristics, such as bottom temperature, productivity, as well as sediment texture, influenced the relative frequencies of ostracode species over small spatial scales. On the larger biogeographic scale, synoptic ordination analyses showed dominant species-N. leioderma (Bering Sea), P. pseudopunctillata (offshore Chukchi and Beaufort Seas), and S. bradii (all regions)-remained fairly constant over recent decades. However, during 2013-2018, northern Pacific species M. mananensis and S. ikeyai increased in abundance by small but significant proportions in the Chukchi Sea region compared to earlier years. It is yet unclear if these assemblage changes signify a meiofaunal response to changing water mass properties and if this trend will continue in the future. Our new ecological data on ostracode species and biogeography suggest these hypotheses can be tested with future benthic monitoring efforts.

The mysterious ecosystem at the ocean's surface.

Life on the ocean's surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found therein. Organisms that live freely at the surface, termed "neuston," include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean's surface harbors unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Despite the diversity and importance of the ocean's surface in connecting disparate habitats, and the risks it faces, we know very little about neustonic life. This Essay will introduce you to the neuston, their connections to diverse habitats, the threats they face, and new opportunities for research and discovery at the air-sea interface.

Reduction of roadway noise in a coastal city underwater soundscape during COVID-19 confinement.

Confinement due to the COVID-19 pandemic drastically reduced human activities. Underwater soundscape variations are discussed in this study, comparing a typical and confinement day in a coastal lagoon near a popular tourist city in Mexico. Recording devices were located at 2 m in depth and 430 m away from the main promenade-a two-way avenue for light vehicle traffic-where main tourist infrastructure is located. The nearby marine environment is habitat to birds and dolphins as well as fish and invertebrates of commercial importance. Medium and small boats usually transit the area. The main underwater sound level reduction was measured at low frequencies (10-2000 Hz) because of the decrease in roadway noise. Vessel traffic also decreased by almost three quarters, although the level reduction due to this source was less noticeable. As typical day levels in the roadway noise band can potentially mask fish sounds and affect other low frequency noise-sensitive marine taxa, this study suggests that comprehensive noise analysis in coastal marine environments should consider the contribution from nearby land sources.

Modelling seasonal patterns of larval fish parasitism in two northern nearshore areas in the Humboldt Current System.

Macro- and micro-environmental factors modulate parasite loads in fish, determining parasitic abundances, diversity, and interaction dynamics. In this study, seasonal variations in larval ectoparasites on fish larvae in the northern Humboldt Current System (HCS) were evaluated using a delta-gamma generalized linear model to predict their occurrence frequencies. Fish larvae were collected from two nearshore areas during austral spring-summer and autumn-winter. Only five (of 38) larval fish species were parasitized by copepods: Gobiesox marmoratus, Ophiogobius jenynsi, Helcogrammoides cunninghami, Myxodes sp., and Auchenionchus crinitus. A binomial model showed that the presence/absence of parasitized fish larvae varied among the fish species and their larval abundances, while a positive delta-gamma model showed that ectoparasite frequency varied among the seasons and fish species. Seasonal variations in parasitized fish larvae frequency could be associated with host and parasite reproductive processes, which are related to oceanographic features responsible for larval retention and subsequent higher infestation probabilities. Host length was positively correlated with ectoparasite length, suggesting early infection and combined growth until the detachment of the ectoparasite. Our results suggest that infestation patterns in larval fish species can be identified using delta-gamma models and that they respond to local (retention) and high-scale (HCS) processes.

Ciguatera fish poisoning in France: experience of the French Poison Control Centre Network from 2012 to 2019.

INTRODUCTION: Ciguatera fish poisoning (CFP) is a common Poisoning in the tropical countries. France is directly concerned with French tourists in endemic area and with French citizens living in the French overseas territories. METHOD: Retrospective, descriptive study of CFP cases handled by the French Poison Control Centre Network from 2012 through 2019. RESULTS: Fifty-two events were studied concerning 130 patients. The fish species was identified for 41 events, mainly belonging to five fish families: 14 groupers, 11 snappers, 5 jacks, 4 parrotfishes, 4 barracudas. The origin of the fish was the Atlantic Ocean (23 events), the Indian Ocean (17 events) and the Pacific Ocean (12 events). 91% of the poisonings occurring in the Atlantic Ocean began with gastrointestinal effects while in 44% of events occurring in the Pacific Ocean, the patients had no gastrointestinal effects (onset with neurological symptoms: paraesthesia and dysesthesia). The evolution of the 130 patients has been classic for CFP with persistent symptoms during 1 to 45 weeks. Numerous patients reported exacerbation of neurological signs several months after poisoning following consumption of alcoholic beverages (23 patients) or seafood (19 patients). DISCUSSION: Medical practitioners in Europe must be trained to manage CFP as cases are reported with tourists returning from endemic areas but also with poisoned patients far from tropical areas after consumption of imported fish.

Reefing Viability Index for Rigs-to-Reefs (R2R) in Malaysia.

Decommissioning of the offshore platform as an artificial reef, known as Rigs-to-Reefs (R2R), has become a sustainable approach for oil companies. The platform was reused to serve the underwater ecosystem as an artificial reef for a new marine ecosystem which helps to tackle food security issue. This paper presents the findings of the formulation of the reefing viability index to recognize an offshore region that can be used for R2R projects within the South China Sea. The combined effects of spatial data, numerical modelling, and geographic system (GIS) are proposed to study the relationship of spawning ground coral reefs, diversity, and planula larvae in the process of colonization to establish a map of the reef potential environment. Coral connectivity and spawning behaviour were studied to determine the possible source of coral seedling released during the spawning season, twice a year. A geographic reef viability index was established consisting of seven parameters which are coral larval density, pelagic larval length, sea currents, temperature, chlorophyll-a, depth, and substrate availability. The ocean hydrodynamic model was designed to resemble the pattern of larval scattering. By using the simulations and rankings, there were 95 (21%) sites which could probably be used for in situ reefing, whereas 358 (79%) sites were likely ideal for ex situ reefing. Validation of the viability index was carried out using media footage assessment of remotely operated vehicle (ROV).

Addressing distribution equity in spatial conservation prioritization for small-scale fisheries.

Spatial conservation prioritization is used worldwide for designing marine protected areas (MPA) that achieve set conservation objectives with minimal impacts to marine users. People involved in small-scale fisheries (SSF) may incur negative and disproportionate impacts from implementing MPAs, yet limited available data often restricts their representation in MPA planning. Using a Philippines case study, we focus here on the systematic design of a MPA network that aims to minimize and distribute costs equitably for SSF whilst achieving representation targets for biodiversity conservation. The objectives of the study are to: (1) document a participatory mapping approach for collecting SSF data for prioritization using the local knowledge of fishers; and (2) examine how the completeness and resolution of SSF data may affect prioritization outputs in terms of biodiversity representation, spatial efficiency, and distribution equity. In the data-poor region, we conducted participatory mapping workshops with fishers in 79 communities to collect data on the spatial distribution patterns of different SSF fisheries and communities, and employed remote sensing techniques to define coastal habitats, which were targeted for inclusion in MPAs. The datasets were integrated within the decision-support tool Marxan with Zones to develop three scenarios. The SSF data incorporated in each scenario varied based on their completeness (considered all fishing methods or only dominant methods) and resolution (fishing methods itemized by community or municipality). All scenarios derived MPA plans that met representation targets with similar area coverage. The outputs, however, varied in terms of distribution equity, measured by the distribution of opportunity costs (loss of fishing grounds) across different fisheries and communities. Scenarios that did not include minority fisheries or variations between communities, led to inequitable costs. These results highlight the need to incorporate detailed data on SSF at appropriate resolutions, and how this can be achieved through participatory approaches.

Vertical and geographic distribution of copepod communities at late summer in the Amerasian Basin, Arctic Ocean.

Zooplankton plays a pivotal role in linking primary production to higher level consumers in the food webs of marine ecosystems. The distribution of zooplankton is affected by general water conditions, monsoons, currents, and spatial and temporal factors. In the Arctic Ocean, the sea surface is naturally covered with ice. Under ice, water masses interplay to create complex environments that facilitate the transport and distribution of zooplankton, thus altering community structures at geospatial and vertical scales. The present study investigated the species composition and copepod community structures by using geospatial and multiple depth scales, and using multivariate analyses to evaluate the relation of sampling stations and layers. During July-August 2010, zooplankton samples were collected and the temperature and salinity of seawater measured from three stations in the Canada Basin and two stations in the Makarov Basin of the Arctic Ocean (maximum distance of approximately 1400 km). A total of 55 copepod species (including 25 species that were solely identified to the generic level) and 7 taxa of copepodites, altogether belonging to 28 genera, 11 families, and 2 orders were identified, and significant differences were detected in copepod community structures among sampling strata and at geospatial scales. Numerically, Calanus hyperboreus, Calanus copepodite, Calanoida copepodite, Calanus glacialis, and Metridia longa were the most dominant species and taxa. At the local scale, copepod compositions responded differently at each of the sampling stations. At the geospatial scale, the distance between stations MS03 and ICE explained variations in the pattern of dominant species and of copepod community richness. Our study demonstrated varied spatial distribution which indicates that (1) the abundance of copepods at 0-200 m was significantly higher than at other strata, (2) vertical strata affected the distribution of copepod communities, and (3) the interplay of North Pacific and Atlantic waters shaping the copepod assemblage structure at geospatial scales in the Arctic Ocean. The results of our research provide base data for Arctic zooplankton biodiversity and biogeographic distribution.

Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides).

Multihost infectious disease outbreaks have endangered wildlife, causing extinction of frogs and endemic birds, and widespread declines of bats, corals, and abalone. Since 2013, a sea star wasting disease has affected >20 sea star species from Mexico to Alaska. The common, predatory sunflower star (Pycnopodia helianthoides), shown to be highly susceptible to sea star wasting disease, has been extirpated across most of its range. Diver surveys conducted in shallow nearshore waters (n = 10,956; 2006-2017) from California to Alaska and deep offshore (55 to 1280 m) trawl surveys from California to Washington (n = 8968; 2004-2016) reveal 80 to 100% declines across a ~3000-km range. Furthermore, timing of peak declines in nearshore waters coincided with anomalously warm sea surface temperatures. The rapid, widespread decline of this pivotal subtidal predator threatens its persistence and may have large ecosystem-level consequences.

An update on Toxoplasma gondii infections in northern sea otters (Enhydra lutris kenyoni) from Washington State, USA.

Toxoplasmosis in marine mammals is epidemiologically and clinically important. Toxoplasma gondii antibodies (by modified agglutination test, cut-off ≥1:25) were detected in serum of 65 of 70 (92.9%) northern sea otters (Enhydra lutris kenyoni) from Washington State, USA. Brains and/or muscles of 44 sea otters were bioassayed in mice (INF-γ knock-out [KO], Swiss Webster outbred [SW]) and viable T. gondii was isolated from 22 of 44 (50%); T. gondii strains were lethal to KO mice but not SW mice. These T. gondii isolates were further propagated in cell culture. Multi-locus PCR-RFLP genotyping of cell culture-derived tachyzoites revealed four different genotypes among 22 isolates including ToxoDB PCR-RFLP genotype #5 (14 isolates), #1 (three isolates), #3 (four isolates), and #167 (one isolate). PCR-DNA sequencing based genotyping using polymorphic gene GRA6 revealed one of four different alleles. Among the 14 RFLP genotype #5 strains, 10 have GRA6 sequences that match with the Type A, one match with the Type X, two strains did not generate sequence data, and one strain had double peaks at known polymorphic sites indicating a mixed infection. The seven strains belong to genotypes #1 and #3, all have identical sequences to T. gondii Type II reference isolate ME49. Genotype #167 strain has identical sequence to Type I reference strain. In summary, we observed high seroprevalence, and high rate of isolation of T. gondii from northern sea otters and predominant genotype #5 that has been previously reported a dominant and widespread strain among terrestrial wildlife in North America. GRA6 sequence analysis of the genotype #5 isolates indicated the dominance of Type A lineage in sea otters in Washington State.

Antidepressants in a changing ocean: Venlafaxine uptake and elimination in juvenile fish (Argyrosomus regius) exposed to warming and acidification conditions.

The presence of antidepressants, such as venlafaxine (VFX), in marine ecosystems is increasing, thus, potentially posing ecological and human health risks. The inherent mechanisms of VFX uptake and elimination still require further understanding, particularly accounting for the impact of climate change-related stressors, such as warming and acidification. Hence, the present work aimed to investigate, for the first time, the effects of increased seawater temperature (ΔT°C = +5 °C) and pCO2 levels (ΔpCO2 ∼1000 µatm, equivalent to ΔpH = -0.4 units) on the uptake and elimination of VFX in biological tissues (muscle, liver, brain) and plasma of juvenile meagre (Argyrosomus regius) exposed to VFX through two different exposure pathways (via water, i.e. [VFX ] ∼20 µg L-1, and via feed, i.e. [VFX] ∼160 µg kg-1 dry weight, dw). Overall, results showed that VFX can be uptaken by fish through both water and diet. Fish liver exhibited the highest VFX concentration (126.7 ±â€¯86.5 µg kg-1 and 6786.4 ±â€¯1176.7 µg kg-1 via feed and water exposures, respectively), as well as the highest tissue:plasma concentration ratio, followed in this order by brain and muscle, regardless of exposure route. Both warming and acidification decreased VFX uptake in liver, although VFX uptake in brain was favoured under warming conditions. Conversely, VFX elimination in liver was impaired by both stressors, particularly when acting simultaneously. The distinct patterns of VFX uptake and elimination observed in the different scenarios calls for a better understanding of the effects of exposure route and abiotic conditions on emerging contaminants' toxicokinetics.

Organic carbon source and salinity shape sediment bacterial composition in two China marginal seas and their major tributaries.

Marginal sea sediments receive organic substrates of different origins, but whether and to what extent sediment microbial communities are reflective of the different sources of organic substrates remain unclear. To address these questions, sediment samples were collected in two connected China marginal seas, i.e., Bohai Sea and Yellow Sea, and their two major tributaries (Yellow River and Liao River). Sediment bacterial community composition (BCC) was examined using 16S rRNA gene pyrosequencing. In addition, physicochemical variables that describe environmental conditions and sediment features were measured. Our results revealed that BCCs changed with salinity and organic carbon (OC) content. Members of Gaiellaceae and Comamonadaceae showed a rapid decrease as salinity and phytoplankton-derived OC increased, while Piscirickettsiaceae and Desulfobulbaceae exhibited an opposite distribution pattern. Differences of riverine vs. marginal sea sediment BCCs could be mostly explained by salinity. However, within the marginal seas, sediment BCC variations were mainly explained by OC-related variables, including terrestrial-derived fatty acids (Terr_FA), phytoplankton-derived polyunsaturated fatty acids (Phyto_PUFA), stable carbon isotopes (δ13C), and carbon to nitrogen ratio (C/N). In addition to environmental variables, network analysis suggested that interactions among individual bacterial taxa might be important in shaping sediment BCCs in the studied areas.

Is Marine Dispersion of the Lethargic Crab Disease Possible? Assessing the Tolerance of Exophiala cancerae to a Broad Combination of Salinities, Temperatures, and Exposure Times.

Since 1997, an emergent fungal disease named lethargic crab disease (LCD) has decimated stocks of the edible mangrove land crab Ucides cordatus (Linnaeus, 1763) (Brachyura: Ocypodidae) along the Brazilian coast, threatening the mangrove ecosystem and causing socioeconomic impacts. Evidence from a variety of sources suggests that the black yeast Exophiala cancerae (Herpotrichiellaceae, Chaetothyriales) has been responsible for such epizootic events. Based on the spatiotemporal patterns of the LCD outbreaks, the well-established surface ocean currents, and the range of ecological traits of Exophiala spp., a marine dispersal hypothesis may be proposed. Using in vitro experiments, we tested the survival and growth of E. cancerae CBS 120420 in a broad combination of salinities, temperatures, and exposure times. While variation in salinity did not significantly affect the growth of colony-forming units (CFUs) (P > 0.05), long exposure times visibly influenced an increase in CFUs growth (P < 0.05). However, higher temperature (30 °C) caused a reduction of about 1.2-fold in CFUs growth (P < 0.05). This result suggests that sea surface temperatures either above or below the optimum growth range of E. cancerae could play a key role in the apparent north-south limits in the geographical distribution of LCD outbreaks. In light of our results, we conclude that a fundamental step toward the understanding of LCD epidemiological dynamics should comprise a systematic screening of E. cancerae in estuarine and coastal waters.

Avian Cholera Causes Marine Bird Mortality in the Bering Sea of Alaska.

The first known avian cholera outbreak among wild birds in Alaska occurred during November 2013. Liver, intestinal, and splenic necrosis consistent with avian cholera was noted, and Pasteurella multocida serotype 1 was isolated from liver and lung or spleen in Crested Auklets (Aethia cristatella), Thick-billed Murres (Uria lomvia), Common Eider (Somateria mollissima), Northern Fulmars (Fulmarus glacialis), and gulls (Larus spp.).

Comparison of hospitalization among German coastal and deep sea fishermen.

PURPOSE: This study aims to compare the hospitalization of German fishermen employed on German-flagged fishing vessels with that of the general German population in consideration of differences between coastal and deep sea fishery. METHODS: By means of a database from the health insurance company for seafarers, diagnoses of German fishermen treated in German hospitals were determined from January 1997 to December 2007. Compared with the general German population, the fishermen's risk for specific diseases leading to hospitalization was calculated as standardized hospitalization ratio (SHR). RESULTS: Compared with the German reference population, German fishermen showed a considerably high SHR for malignant neoplasms at all sites (SHR 1.46; 95% CI 1.37-1.56), for respiratory cancer, and for non-Hodgkin lymphoma (NHL). Furthermore, they had more often been hospitalized due to diabetes mellitus, diseases of the respiratory and digestive systems as well as due to injury and poisoning. The risk for respiratory cancer and NHL among coastal fishermen exceeded that of deep sea fishermen, whereas the latter displayed a considerably higher SHR for diabetes mellitus, diseases of the respiratory system and metabolic and nutritional disorders. In contrast, the SHR for hypertensive and ischemic heart diseases was decreased among deep sea fishermen. Less qualified deep sea fishermen displayed a considerably higher SHR for malignant neoplasms at all sites than more highly qualified ones. CONCLUSIONS: Fishery is still an occupation which poses a high risk for malignant neoplasms and injuries. This is likely due to lifestyle and work-related factors. Further studies are needed to evaluate the different working and living conditions of coastal and deep sea fishermen.

Morphological and genetic characteristics of the anisakid nematode Raphidascaris acus from the southwest Caspian Sea: evidence for the existence of sibling species within a species complex.

Recently, it has been shown that many nematode species are in fact species complex, using exact morphological and genetic studies. In this case, there are no such studies related to the genus Raphidascaris Railliet & Henry, 1915. Herein, the morphological and genetic variations among the Iranian population of the species Raphidascaris acus (Bloch, 1779) Railliet & Henry, 1915 and the other allopatric populations with morphological and genetic information were compared to show whether this species can be considered as a species complex. R. acus is an anisakid species and has been frequently reported from different host species from the Caspian Sea. Nonetheless, there are no morphological and genetic information for this species from the region. In the present study, a total of 20 specimens of R. acus were collected from Esox lucius Linnaeus, and the morphology of the Caspian population of this species was surveyed for the first time using both light and scanning electron microscopy. Meanwhile, some parts of ribosomal DNA (rDNA) including internal transcribed spacer 1 (ITS1), 5.8 s, and ITS2 were sequenced and presented as the genetic marker for this species. To understand whether R. acus can be considered as a species complex, the Caspian population of this species was compared morphologically with the allopatric populations of Czech and Canada and genetically with the allopatric population of Poland (Vistula lagoon). Morphologically, there was no difference between the Caspian and Czech populations, but the Caspian and Canadian populations differed in the length of ejaculatory duct and the presence of small triangular elevation between the bases of subventral lips. The nucleotide difference between the Caspian and Polish populations was 4.48%. In comparison with the interspecific genetic distances in the genus Raphidascaris, this value is notable. In conclusion, based on morphological and genetic differences among the allopatric populations of R. acus, this species is probably a species complex. Nonetheless, the definitive taxonomic decision in recognizing R. acus as a species complex and the description of its sibling species depend on surveying other allopatric populations morphologically and genetically accompanied by an evaluation of reproductive isolation among them.

Detection of salmonid alphavirus RNA in Celtic and Irish Sea flatfish.

Pancreas disease (PD) caused by the salmonid alphavirus (SAV) has been the most significant cause of mortalities in Irish farmed salmon Salmo salar L. over the past decade. SAV is a single-strand positive-sense RNA virus, originally thought to be unique to salmonids, but has recently been detected using real-time RT-PCR in a number of wild non-salmonid fish. In the present report, 610 wild flatfish (common dab Limanda limanda, plaice Pleuronectes platessa and megrim Lepidorhombus whiffiagonis) were caught from the Irish and Celtic Seas and screened for SAV using real-time RT-PCR and sequencing. In general, a very low prevalence was recorded in common dab and plaice, except for 1 haul in Dublin Bay where 25% of common dab were SAV-positive. SAV sequence analysis supported the fact that real-time RT-PCR detections were specific and further characterised the detected viruses within SAV Subtype I, the predominant subtype found in farmed salmon in Ireland.