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Copyright of Ecological Applications is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we present a study about an automated system for monitoring underwater ecosystems. The system here proposed is based on the fusion of different deep learning methods. We study how to create an ensemble based of different Convolutional Neural Network (CNN) models, fine-tuned on several datasets with the aim of exploiting their diversity. The aim of our study is to experiment the possibility of fine-tuning CNNs for underwater imagery analysis, the opportunity of using different datasets for pre-training models, the possibility to design an ensemble using the same architecture with small variations in the training procedure. Our experiments, performed on 5 well-known datasets (3 plankton and 2 coral datasets) show that the combination of such different CNN models in a heterogeneous ensemble grants a substantial performance improvement with respect to other state-of-the-art approaches in all the tested problems. One of the main contributions of this work is a wide experimental evaluation of famous CNN architectures to report the performance of both the single CNN and the ensemble of CNNs in different problems. Moreover, we show how to create an ensemble which improves the performance of the best single model. The MATLAB source code is freely link provided in title page. [ABSTRACT FROM AUTHOR]

Estuarine environments are influenced by both river flows and oceanic tidal movement of water, sediment, and nutrients, often forming ecosystems that are rich in resources and biodiversity. The Yellow River once carried the world's largest sediment load, but artificial structures have transformed its hydrodynamic processes. An annual Water–Sediment Regulation Scheme (WSRS) was introduced to flush accumulated sediment from the Xiaolangdi Reservoir, which provides flood control and water storage. However, the effect of the WSRS process on the runoff and sediment conditions, nutrients, and ecological environment of the Yellow River Estuary and adjacent ocean are not well understood. In the current study, a coupled hydrodynamic–nutrient–plankton ecosystem dynamics model (FVCOM–FABM–NPZD) was constructed to simulate changes in the ecological parameters and in the vertical response in the Yellow River Estuary before, during, and after the WSRS, This model also was used to quantify the effects of changes in the incoming material flux on the hydrodynamic and ecological environment of the estuary, using the Yellow River Xiaolangdi Reservoir water transfer and sand transfer as an example. The study found that the WSRS changed the spatial and temporal distribution of temperature, salinity, sediment, inorganic nitrogen, and phytoplankton in the Yellow River Estuary and adjacent waters. It also had a significant effect on the temperature, salinity, and ecology of the adjacent near-shore marine environment. The spatial and temporal responses of zooplankton and phytoplankton to the WSRS differed. Zooplankton showed a lag in response to the WSRS and were mainly influenced by temperature and phytoplankton. The phytoplankton concentration was positively influenced by inorganic nitrogen and negatively influenced by salinity and sediment. In the current study, the effects of changes in the flow and sediment flux from the WSRS on environmental factors and zooplankton in the Yellow River Estuary were simulated, providing a theoretical basis for scheduling the release of water and sediment in the Yellow River basin and providing a reference for water and sediment regulation in other reservoirs upstream of the estuary. [ABSTRACT FROM AUTHOR]

Dimensions of particulate matter found in the water column of marine and freshwater environments (the pelagic realm) range from nanometers to tens of meters. Included in this enormous size range are miniature bacteria, phytoplankton (photosynthetic microalgae), mixoplankton (mixotrophic microorganisms), micro- to meter sized drifting animals (zooplankton), plastic particles, detrital aggregates and fecal pellets, fish, whales and many others. These particles and organisms are involved in many different processes and perform a multitude of services, such as in oceanic biogeochemistry (carbon fixation, oxygen production, carbon export and others) or human nourishment (fisheries). Digital optical tools used in pelagic imaging approaches now allow to bridge this enormous size span and to image micro- to meter-sized objects in situ or on discrete samples. Monitoring plankton, nekton, and particle dynamics at spatial and temporal scales that enable effective management of marine and freshwater environments poses a collective challenge for society. We here argue that a global, distributed and operational network for pelagic imaging is needed and within reach, and we provide recommendations how it can be attained via the voluntary activities of the pelagic imaging community and strategic support from funding agencies and other stakeholders. [ABSTRACT FROM AUTHOR]

The impact of polycyclic aromatic hydrocarbons (PAHs) on the marine food web is crucially understudied in the primary trophic system. We evaluated the seasonal dynamics of PAHs in microplankton in a polluted environment (Taiwan), northeastern South China Sea. Replicate size-fractionated microplankton (55–1000 μm) were freeze-dried, and PAHs were extracted with a 1:1 v /v ratio of acetone: n-hexane, then analyzed using GC–MS. Total PAHs ranged between 68 and 2548 ng/g dw in microplankton, greatest during spring (130–2548 ng/g), followed by autumn (135–772 ng/g) and summer (44–423 ng/g). Spatial distribution varied through seasons but was higher in the southern part (S6 > S4 > S5 > S2 > S3 > S1 > S7), dominated by higher-ring PAHs from mixed pyrogenic and petrogenic sources. PAHs are significantly correlated with environmental factors, especially in colder seasons and lower salinity areas. Suspended matter and plankton influenced PAH transport and partitioning seasonally. Plankton's PAHs seasonal changes and environmental influences are revealed in an anthropic environment. [Display omitted] • PAH concentrations in estuarine microplankton change with season. • Higher ring PAHs dominate composition in microplankton. • Mixed sources of PAHs contribute to microplankton PAH contamination. • Environmental impacts on PAHs in microplankton vary with season. • First report on PAH seasonal changes in harbor microplankton. [ABSTRACT FROM AUTHOR]

Early detection of aquatic invasive species (AIS) is vital to cost-effective prevention of their spread in the Great Lakes. Unfortunately, AIS surveillance has been generally too slow and geographically limited to support this purpose. Environmental DNA (eDNA) detection using quantitative polymerase chain reaction (qPCR) offers more rapid and affordable detection of likely AIS presence, but it does not directly discern live/dead status. Vital status verification using conventional surveys following positive eDNA qPCR detections could resolve this barrier, but only if the latter are adequately reliable and sensitive. Here we explore the reliability and sensitivity of eDNA qPCR monitoring for the bloody red shrimp (Hemimysis anomala), an AIS established in the southern Great Lakes but not yet widely distributed in Lake Superior, against conventional microscopy-based methods. We conducted this comparison using 1) harbor water from Muskegon Lake, MI where H. anomala is established, and 2) raw ballast water from ships transporting ballast from lower Lake Michigan to western Lake Superior. Our studies showed positive eDNA qPCR detections of H. anomala in all harbor and ballast samples for which conventional detection results were positive, and in some samples for which conventional results were negative. These results suggest that qPCR assays with adequate specificity could be an important tool in support of more effective and affordable early detection of target species in Great Lakes water, especially when combined with confirmatory conventional monitoring. [ABSTRACT FROM AUTHOR]

An assessment of plankton distribution along with physical and chemical parameters was undertaken in different altitudinal lakes of Arunachal Pradesh. The sampling and data analysis was performed following standard methods. Out of the total 66 species recorded, 15 species commonly occurred namely Amphora sp., Bulbochaete sp., Closterium sp., Cymbella sp., Lyngbya sp., Mougeotia scalaris, Navicula sp., Nitzschia sp., Oedogonium sp., Pinnularia sp., Spirogyra sp., Stauroneis sp., Surirella sp., Synedra sp. and Zygnema sp. Ganga Lake recorded the highest 33 species while Bone Lake recorded the lowest 7 species. Bacillariophyceae was dominant representing 22 species while Chrysophyceae, Dinophyceae, Euglenophyceae and Klebsormidiophyceae recorded only 1 species each. We found slight variations in physical and chemical properties due to altitude. The conductivity ranged between 4µS/cm (Kyalem) to 60µS/cm (Bone); total dissolved solid ranged between 5mg/L (Sela) to 22mg/L (Mehao); pH between 6.8 (Mehao) to 9.3 (Hireng); dissolved oxygen ranged between 4.77 mg/L (Kyalem) to 15.4 mg/L (Hireng); free carbon dioxide between 0.23 mg/L (Ganga) to 1.2 mg/L (Nagula); alkalinity between 3.4 mg/L (Mehao) to 8.2 mg/L (Hireng) and hardness recorded was between 3.7 mg/L (Mehao) to 17 mg/L (Pegu). The present findings provide baseline data on phytoplankton distribution and water quality of different altitudinal lakes in the Arunachal Himalayan Region. [ABSTRACT FROM AUTHOR]

Drivers of lower food web composition and productivity in Lake Ontario have undergone extensive changes in the last 40 years, including nutrient abatement, fluctuations in planktivores (Alewife), and invasion by dreissenid mussels and predatory cladocerans. Temporally intensive long-term index stations are critical for understanding these drivers and interpreting the results of periodic lake-wide spatially intensive surveys such as Cooperative Science and Monitoring Initiative (CSMI). We compare epilimnetic physical–chemical parameters and zooplankton metrics at a Kingston Basin biomonitoring site (Station 81) over three time stanzas (1981–1986, 1987–1995 and 2007–2017). In the most recent stanza, mean May-October temperature increased by 2.5 °C, and despite static total phosphorus levels, chlorophyll has significantly decreased and Secchi depth has increased. Between Stanzas 2 and 3, epilimnetic density, biomass and production of crustacean zooplankton have declined by 88%, 79% and 67%, respectively. Bosminids, Daphnia retrocurva , Diacyclops and juvenile cyclopoids are most impacted, whereas larger taxa (calanoids, Daphnia galeata , Holopedium and predatory cladocerans) have remained stable or increased. While some taxa have increased in size over time, zooplankton egg ratios have remained stable. Dreissenid veligers are now numerically dominant and have replaced some of the lost crustacean production. Redundancy Analysis showed environmental drivers (Secchi and temperature) significantly influenced zooplankton during the 1981–1995 period but not in the recent stanza. Alewife were not a significant driver despite substantial declines since the 1990s. Resource competition by Dreissena for the strongly reduced phytoplankton productivity, combined with predation by invasive cladocerans Cercopagis and Bythotrephes have also likely influenced Kingston Basin zooplankton. [ABSTRACT FROM AUTHOR]

The Sambia Peninsula (Kaliningrad region) is historically well known for its amber mining. The 2019 year was the last year of direct overburden disposal into the Baltic Sea as a part of technological amber mining process. The extremely high-suspended particulate matter concentrations during that disposal were recorded immediately after the discharge of significant volumes of pulp and reached 200 mg/L. The impact of pulp discharge had sequentially suppressed plankton communities development due to the high content of suspended solids and afterwards stimulated plankton development due to the glauconite infusion. Cladocera were the most sensitive group to the effects of suspended matter. According to the preliminary forecast, when the pulp discharge stops, the restoration of plankton communities may take from 1 to 2 seasons to 1 year for different groups. This is due to the timing of the removal of fine suspended particulate matter from sediments and the possibility of secondary entry during resuspension. • Amber open-pit mining causes suspended particulate matter concentration rise in discharge area to extreme level >100 mg/L. • Extreme suspended matter concentrations affect benthos communities negatively in a broader way than plankton communities. • Long-term effect on benthos is more severe, while plankton may benefit from glauconite from overburden discharge. [ABSTRACT FROM AUTHOR]

The present study combined the data of environmental parameters and plankton distribution using hydroacoustic technology with the purpose to map the horizontal and vertical distribution of plankton in Yos Sudarso Bay, Jayapura, Indonesia. Hydroacoustic data were processed using a threshold in the range of −90 dB to −70 dB which was used for plankton detection at a depth range of 5–100 m. The results of the current study showed that the surface temperature changed from 30 °C on the outside to 18 °C on the inside of the bay. Similarly, the salinity of the surface outside the bay was 36‰ while it was 18‰ inside the bay. The distribution of chlorophyll had also decreased, where the value outside the bay was 0.32 mg/m3 and inside the bay was 0.02 mg/m3. The horizontal distribution of the values of plankton's volume backscattering strength (Sv) had a range of −82 dB to −75 dB with an average of −76.63 dB. When the distribution of plankton's Sv was detected vertically, it showed that the value of plankton's Sv decreased with increasing the water depth. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To better understand zooplankton dynamics in Lake Ontario's Toronto Harbour and adjacent coastal area (CA), we sampled zooplankton, phytoplankton, nutrients and physical parameters on six dates in 2016. Despite higher levels of nutrients, chlorophyll and primary production in the inner harbor (IH), the areas supported similar May to November zooplankton biomass (IH = 32 ± 7 and CA = 42 ± 10 mg/m3). IH values were much lower than other nutrient-enriched embayments in Lake Ontario, yet CA biomass was twice that of nearshore sites away from Toronto. Small zooplankton such as rotifers and Bosmina dominated IH; and large taxa (Daphnia , calanoids and predatory cladocerans) were more important in the CA. Daphnia , Bosmina , cyclopoids and calanoids were larger in the CA, and adult cyclopoids had higher egg ratios. This led to low annual IH production estimates for both cyclopoid and calanoid copepods. Total phosphorus and chlorophyll did not appear to regulate zooplankton biomass, but positive relationships were found with bacterial biomass in the IH and with temperature in the cool season. Atypically high fish planktivory rates likely suppressed larger IH zooplankton in 2016, allowing small, resilient Bosmina to flourish and contribute 84% of total production in the IH. Comparing 2016 data to previous zooplankton surveys revealed considerable inter-annual variation in proportions of Daphnia , Bosmina and predatory cladocerans over the 1994 to 2016 period, and the strong top-down controls observed in 2016 were not typical. Elevated microbial production may serve as an important alternate trophic pathway supporting cladoceran populations in Toronto Harbour. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A recent model demonstrated that the adenosine triphosphate (ATP) content of spherical aquatic organisms with a 10 to 50 μm diameter is between 0.16 and 19.9 pg cell−1. Here, the model is validated by comparing microscopy-based counts with ATP concentrations from a commercial ATP kit. The measured ATP content of both freshwater and marine organisms 10 to 50 μm size range falls in the 0.16 to 19.9 pg cell−1 model range. On average, freshwater organisms contain 0.33 pg ATP cell−1, have a spherical equivalent diameter (SED) of 13 μm, while marine organisms have 0.89 pg ATP cell−1 and a SED of 18 μm. In addition, their 13 to 18 μm size is within the 10 to 50 μm ballast water size range and in agreement with the 15 μm mean SED of a coastal plankton size-distribution model. This study concludes that the ATP-model is reliable, emphasizing the need for caution when converting three-dimensional biomass proxies into linear cell concentrations. • A recent model demonstrated that the ATP content of spherical aquatic organisms with a 10 to 50 μm diameter is between 0.16 to 19.9 pg cell-1. The model was validated by comparing microscopy-based counts with ATP concentrations from a commercial ATP kit. • On average, freshwater organisms contain 0.33 pg ATP cell-1, have a spherical equivalent diameter (SED) of 13 μm, while marine organisms have 0.89 pg ATP cell-1 and a sed of 18 μm. • The ATP content of both marine and freshwater organisms falls in the 0.16 to 19.9 pg cell-1 model range. Their 13 to 18 μm SED is within the 10 to 50 μm ballast water size range and in agreement with the average of 15 μm SED of a coastal plankton size-distribution model. • This study concludes that the ATP-model is reliable, emphasizing the need for caution when converting three-dimensional biomass proxies into linear cell concentrations. [ABSTRACT FROM AUTHOR]

Franz Josef Land (FJL) is a remote archipelago that has become more accessible for large-scale studies due to recent warming. This paper summarizes recent survey findings on oceanography, climate, plankton, and benthic communities conducted in FJL. Cold Arctic waters predominantly affect FJL, but an increased inflow of warmer Atlantic water has been observed in recent decades. The bacterioplankton in FJL is mainly comprised of ultra-small bacterial cells, which make up to 60% of the biomass. Phytoplankton are predominantly composed of cells smaller than 20 μm, with the greatest concentrations found above the pycnocline. The population of larger microalgae ranges from 4.5 to 1250 thousand cells L−1, with dinoflagellates occupying the euphotic zone, Dinobryon being the most abundant species in the thermocline, and spore-bearing cells of Chaetoceros diatoms dominating in the deepest region. Summer zooplankton comprise large Calanus copepods, smaller copepods, and meroplankton, with an average dry biomass of 114–391 mg m−3. The community structure varies mainly based on water temperature and phytoplankton density, with greater biomasses found in colder offshore waters. August represents the breeding season for plankton populations. The local benthic fauna is diverse and displays high species abundance (3370 ind. m−2) and wet biomass (428 g m−2). There is a distinct vertical stratification in the benthic community structure, evidenced by a consistent decline in both abundance and biomass with increasing depth. The trophic structure is predominantly influenced by food availability, sediments, and currents. The trend of borealization in the Barents Sea biota is supported by recent distribution records of certain boreal benthic species and increased abundances of typical Atlantic zooplankton species. The results of our study establish a foundational dataset to aid in ongoing scientific inquiry, preservation efforts, and strategic decision-making with regards to the natural resources of the FJL region. • The area has a complex oceanography and is influenced mainly by Arctic Water. • Clear spatial and vertical patterns are common in the local biota. • Plankton abundance and biomass peak in August. • Benthic fauna shows high species diversity, abundance, and biomass. • Warming has led to increased taxa abundances and borealization of the fauna. [ABSTRACT FROM AUTHOR]

A baseline study was undertaken on polycyclic aromatic hydrocarbons (PAHs) in phytoplankton. Plankton samples from six stations (duplicates) in Kaohsiung Harbor (KH), Taiwan along with a phytoplankton control sample afar from the harbor, were collected. We applied size-fractionation to isolate phytoplankton (55–120 μm), followed by sedimentation and centrifugation to remove abiogenic particulates. The phytoplankton was freeze-dried, extracted with acetone: n -hexane (1:1, v/v), and analyzed using GC–MS. ΣPAHs in phytoplankton ranged between 5204 and 28,903 ng/g dry weight (mean: 12,150 ng/g). The ΣPAHs in KH were >7 times than the control site (C1: 3972 ng/g). Cluster analysis showed spatial gradients (northern < southern KH). Accumulated PAHs in phytoplankton were from petrogenic (fishing ports and ships) and pyrogenic (river outflows), dominated by lower-ring PAHs, likely due to their higher bioavailability in the dissolved phase. We present a practical phytoplankton isolation technique for more accurate phytoplankton PAH concentrations with insights into their distribution and sources. [Display omitted] • First report on PAHs in size-fractionated marine harbor phytoplankton • Use of simple pre-treatment to isolate and study PAHs in phytoplankton • PAHs accumulated in phytoplankton are from pyrogenic and petrogenic sources. • Fishing ports and rivers are major PAH sources in phytoplankton from study area. [ABSTRACT FROM AUTHOR]

The Chilean Patagonian lakes are characterized by their marked oligotrophic or oligomesotrophic status and low zooplankton species abundances, many of these lakes with oligomesotrophic status is associated to human intervention due towns in their shores. The aim of the present study was determine the relations between spectral properties (LANDSAT/OLI), chlorophyll and plankton abundances in two north Patagonian lakes, Villarica, that has two towns in its shore, and Caburgua, that has native forest in its shores as basis of environmental pollution monitoring tools. The results revealed that Villarica lake has high reflectances in near infrared, red and green bands, high chlorophyll (a, b and c) concentrations, and high bacterial and plankton abundances, whereas Caburgua lakes has low reflectance in the same bands, and low chlorophyll concentrations, low bacterial and plankton abundances, with exception to high mixotrophic ciliates. The obtained results agree with limnological observations about both lakes, and the comparison with spectral properties agree with similar observations for glacial north Patagonian lakes about spectral properties and zooplankton community. [ABSTRACT FROM AUTHOR]

Spatiotemporal relationships between developmental stages (cydippid, transition and adult) of the comb jelly Mnemiopsis leidyi and environmental parameters were seasonally evaluated using the random forest (RF) model along the Iranian coasts of the Caspian Sea. The mean density of M. leidyi in spring, summer, autumn and winter were 8, 54, 130, and 15 ind m−3, respectively. The density of various stages, particularly cydippid, showed a decreasing trend with increase in depth. Cydippids had the highest abundance with a lower percentage in the deeper layers and colder seasons. Temperature was found to be the most influential parameter on the distribution of M. leidyi 's life stages, particularly cydippids, with a stronger effect in spring and summer. The highest densities for all life stages were observed above 20 °C with an explosive growth at above 25 °C for the cydippids. Moreover, cydippids were strongly influenced by all the three stages of the copepod Acartia tonsa (nauplius, copepodite and adult) , especially its later developmental stages. Due to the presence of M. leidyi , the maximum zooplankton abundance has shifted to cold seasons. There was also a relationship between M. leidyi with barnacle larvae and rotifers in the cold seasons. The interrelationships among the life stages of M. leidyi , particularly between the transition and cydippid, was a major factor in its population dynamics. The relationship curves between these environmental parameters and the life stages of M. leidyi were nonlinear and mostly sigmoidal (not absolutely linear). The magnitude of parameter importance and relationships curves varied with season and life stage. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ecological monitoring requires sensitive and effective approaches to detecting polluting substances. One such approach involves tracking the behavioral responses of plankton that is initially adapted to normal habitat conditions. Zooplankton such as Daphnia are filter feeders that are highly sensitive to pollution. We describe how a submersible holographic camera with additional attracting lighting (at a wavelength of 532 nm) can be used to track changes of Daphnia response to light for a number of pollutants, including potassium dichromate and crude oil. Our laboratory experiments showed that the sensitivity of this method of bioanalysis is comparable to standard laboratory methods, but has the additional advantage that it can be used in real time in lakes and other water areas, and hence is more versatile than standard methods. [ABSTRACT FROM AUTHOR]

Zooplankton has been intensively used as bioindicators of water pollution at global level, however, only few comprehensive studies have been conducted from the Mediterranean Sea and manly dated back to the 1970s. To redress the urgent need for updated data, this study provides information on the presence and levels of contaminants in zooplankton from the Tyrrhenian Sea. Although banned, both PCBs (46.9 ± 37.2 ng g−1) and DDT (8.9 ± 10.7 ng g−1) are still present and widespread, but their contamination appears to be a local problem and to be declining over the past 50 years. Zooplankton accumulates high levels of certain TEs, including Zn (400 ± 388 ppm) and Pb (35.3 ± 45.5 ppm), but shows intermediate concentrations of other TEs, including Cd (1.6 ± 0.9 ppm) and Hg (0.1 ± 0.1 ppm), comparing with both strongly polluted and more pristine marine habitats, which may reflect a general improvement. [Display omitted] • This study evaluated the status of contamination of the Mediterranean Sea. • Although banned since the 1970s, POPs are still widespread in zooplankton organisms. • POPs contamination appears to be a local problem, and levels are declining over the past 50 years. • Zooplankton showed a great variability in TE levels among different sampling areas. • Levels of certain TEs are comparable to those of worldwide renowned polluted areas. [ABSTRACT FROM AUTHOR]

Pollution is one of the main anthropogenic threats to marine ecosystems. Studies analysing the accumulation and transfer of contaminants in planktonic food webs tend to rely on samples collected in discrete water bodies. Here, we assessed the representativeness of measurements at the chlorophyll-a maximum layer during the MERITE-HIPPOCAMPE cruise for the entire water column by investigating the vertical distribution of particles and plankton obtained by in-situ optical profilers at nine stations across the Mediterranean Sea. We identified specific conditions where the interpretation of results from contaminant analyses can be improved by detailing plankton size structure and vertical distributions. First, the presence of higher than usual plankton concentrations can result in sampling issues that will affect biomass estimation within each size class and therefore bias our understanding of the contaminant dynamics. Secondly, the presence of an unsampled water layer with high zooplankton biomass might imply non-resolved contaminant pathways along the trophic structure. This study lays the basis for optimizing sampling strategy in contaminant studies. • Interpretation of environmental conditions helps to assess validity of contaminant measurements. • Contaminant transfer across the food web might sometimes occur undetected in the surface layer. • In-situ plankton profilers are valuable tools to enhance the potential of contaminant studies. [ABSTRACT FROM AUTHOR]

Copyright of Revue de Micropaleontologie is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present work aims to investigate the food items and the feeding habits of some Nile fish namely; Alestes baremoze , Labeo niloticus , Mormyrus kannume and Oreochromis niloticus that were collected from El-Qanater Al-Khairia during spring 2018 as well as to study their correlation with live food. The examination of the plankton samples revealed that there were 25 phytoplankton species belonging to 6 phyla of the plant kingdom. The common phytoplankton phyla were Bacillariophyta, Chlorophyta, Cyanophyta, and Dinophyceae. Twenty-five species and other immature stages representing the zooplankton community were categorized in ten groups of the animal kingdom. The dominant groups were Rotifera, Protozoa, Copepoda, Cladocera and Polychaeta. The benthic fauna collected from the study area comprised of 7 groups of the animal kingdom represented in 10 species and other immature stages. The recorded groups were Mollusca, Foraminifera, Annelida, Insecta and Decapoda. The present results showed that the feeding intensity in the studied fish were moderate, being 60% in A. baremoze ; 53.85% in L. niloticus ; 66.67% in M. kannume and 53.57% in O. niloticus. Analysis of the stomach contents revealed that A. baremoze is a plankton feeder and consumed a wide range of phyto- and zooplankton. L. niloticus is majorly herbivorous and consumed a great variety of plant food. M. kannume is mainly a carnivorous benthic feeder consuming a great range of animal food, while O. niloticus is mostly omnivorous consuming high varieties of plant and animal food. The forage ratio of stomach contents showed that A. baremoze and M. kannume are selective feeders. However, L. niloticus and O. niloticus depended on the food availability in nature and selectivity. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) powered ships equipped with an underwater exhaust system to reduce the ship's water resistance could form a future generation of energy-efficient ships. The potential consequences of the underwater exhaust gas to the local ecosystems are still unknown. Especially, the CO2 levels may locally exceed estimated future global levels. The present study exposes marine communities to a wide range of CO2 dosages, resulting in pH 8.6–5.8 that was remained for 49 days. We found that the zooplankton and benthic community were adversely affected by high CO2 exposure levels. In detail, (1) between pH 6.6 and 7.1 polychaete worms became the dominating group of the benthic community and their larvae dominated the zooplankton group. (2) Due to the reduced grazing pressure and the flux of nutrients from decaying organic material planktonic microalgae (phytoplankton) stared blooming at the highest exposure level. The periphyton (fouling microalgae) community was not able to take advantage under these conditions. (3) Marine snails' (periwinkle) shell damage and high mortality were observed at pH < 6.6. However, the growth of the surviving periwinkles was not directly related to pH, but was positively correlated with the availability of periphyton and negatively correlated with the polychaete worm density that most likely also used the periphyton as food source. Our result indicates that the impact of underwater exhaust gasses depends on various factors including local biological and abiotic conditions, which will be included in future research. Article Highlights: A marine mesocosm study was performed with pH levels ranging from 8.6 to 5.8 as a result of CO2 injection. Planktonic algae bloomed in pH 5.8 mesocosms, while low biomass of sessile algae was produced. Polychaete worms dominated the benthic community and their larvae dominated the zooplankton between pH 6.6 and 7.1. High CO2 levels/low pH resulted in shell damage and increased mortality of periwinkles (marine snails). The biomass of periwinkle showed no direct relation with pH, but positive linear correlated with the availability of sessile algae and their major food source. [ABSTRACT FROM AUTHOR]

Abstract Plankton are the most fundamental components of ocean ecosystems, due to their function at many levels of the oceans food chain. Studying and monitoring plankton distribution is vital for global climate and environment protection. Currently, much research is concentrated on the automated recognition of plankton and several imaging-based technologies have been developed for collecting plankton images continuously using underwater image sensors. In this paper, we present a study about an automated plankton recognition system, which is based on the fusion of different deep learning methods. In this work we study both the fine tuning of several deep learned models and transfer learning from the same models with the aim of exploiting their diversity in designing an ensemble of classifiers, we deal with: (i) the ability of fine-tuning pre-trained CNN for plankton classification, (ii) the possibility of using pre-trained CNN for transfer learning, (iii) the possibility of coupling pre-processing to CNN in order to improve their feature extraction capability. The combination of such different descriptors/methods in a heterogeneous ensemble grants a substantial performance improvement with respect to other state-of-the-art approaches based on feature selection and classification. The experimental evaluation on three large publicly available datasets demonstrates high classification accuracy and f-measure of our ensemble with respect to other classifiers on the same datasets. One of the main contributions of this work is a collection of classification models and a wide experimental evaluation to report performance of both single CNN and ensemble of CNNs in different available plankton datasets with a given testing protocol. Moreover, we show how to combine different CNN in order to improve the performance. To encourage future comparisons the MATLAB source code is available in the GitHub repository: https://github.com/LorisNanni. Highlights • Applied deep learning to classify plankton images • Transfer learning and fine-tuning of pre-trained models • Assessing the importance of coupling pre-processing to CNN • Ensembles of deep learning models improve performance with respect to single model • Experiments on 3 datasets proves high classification performance of our ensemble [ABSTRACT FROM AUTHOR]

Abstract Ocean acidification (OA) has potential to affect marine phytoplankton in ways that are partly understood, but there is less knowledge about how it may alter the coupling to secondary producers. We investigated the effects of OA on phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) under present day (400 μatm) and projected end-of-century (1000 μatm) p CO 2 levels. Net primary production was unaffected, although OA did lead to small decreases in growth rates. OA had no measurable effect on micro-/mesozooplankton grazing rates. Elevated p CO 2 had no effect on phytoplankton fatty acid (FA) concentrations during exponential phase, but saturated FAs increased relative to the control during declining phase. FA profiles of mesozooplankton were unaffected. Our findings show that short-term exposure of plankton communities in eutrophic subtropical waters to projected end-of-century OA conditions has little effect on primary productivity and trophic linkage to mesozooplankton. Highlights • Lower apparent growth was observed under elevated CO 2 of 1000 μatm. • Primary production and trophic transfer were unaffected by high CO 2. • Fatty acid profiles of phyto-/zooplankton were unaffected by ocean acidification. [ABSTRACT FROM AUTHOR]

Abstract Lake Baikal is facing several environmental stressors, including climate change and nearshore eutrophication. To assess recent ecological changes in Lake Baikal and provide a baseline for future comparisons, we sampled spring plankton communities from the pelagic zone of the lake in 2016 and compared these data with unpublished and published historical information going back to 1990. In 2016, one pelagic long-term monitoring station was sampled in early spring (March) during ice cover and 21 long-term monitoring stations located throughout the lake were sampled in late spring (May-June). We measured water chemistry parameters at most stations and the abundance, taxonomic composition and biomass of bacteria, ciliates and phytoplankton at several locations in different areas of the lake. Biotic parameters from 2016 were compared with historical data, showing significant changes in the spring pelagic microbial community since the 1990s. We show increased quantities of small species, mixotrophic ciliates, and the appearance (or increasing number) of small coloured and colourless flagellates. We also show substantially decreased densities of formerly dominant heavily silicified diatoms such as Aulacoseira spp. Since 2007, Synedra acus subsp. radians, a smaller and weakly silicified diatom, has dominated the spring plankton of the lake. These results suggest that Lake Baikal's pelagic plankton community may be changing, with climate likely playing a dominant role in these changes. [ABSTRACT FROM AUTHOR]

Abstract Microplastics are abundant and widespread in the marine environment. They are a contaminant of global environmental and economic concern. Due to their small size a wide range of marine species, including zooplankton can ingest them. Research has shown that microplastics are readily ingested by several zooplankton taxa, with associated negative impacts on biological processes. Zooplankton is a crucial food source for many secondary consumers, consequently this represents a route whereby microplastic could enter the food web and transfer up the trophic levels. In this review we aim to: 1) evaluate the current knowledge base regarding microplastic ingestion by zooplankton in both the laboratory and the field; and 2) summarise the factors which contribute to the bioavailability of microplastics to zooplankton. Current literature shows that microplastic ingestion has been recorded in 39 zooplankton species from 28 taxonomic orders including holo- and meroplanktonic species. The majority of studies occurred under laboratory conditions and negative effects were reported in ten studies (45%) demonstrating effects on feeding behaviour, growth, development, reproduction and lifespan. In contrast, three studies (14%) reported no negative effects from microplastic ingestion. Several physical and biological factors can influence the bioavailability of microplastics to zooplankton, such as size, shape, age and abundance. We identified that microplastics used in experiments are often different to those quantified in the marine environment, particularly in terms of concentration, shape, type and age. We therefore suggest that future research should include microplastics that are more representative of those found in the marine environment at relevant concentrations. Additionally, investigating the effects of microplastic ingestion on a broader range of zooplankton species and life stages, will help to answer key knowledge gaps regarding the effect of microplastic on recruitment, species populations and ultimately broader economic consequences such as impacts on shell- and finfish stocks. Graphical abstract Image 1 Highlights • We review the effects of microplastic ingestion on zooplankton • Several factors affect microplastic bioavailability to zooplankton • Microplastics in experiments should better represent those found in the environment •Further investigation of different life stages and zooplankton species is needed Review of the current knowledge regarding microplastic ingestion by zooplankton and summary of factors which contribute to the bioavailability of microplastics to zooplankton. [ABSTRACT FROM AUTHOR]

In this study, we describe morphometric analyses of Orbulina universa morphotypes presently found in the Western South Atlantic, and their relation to the upper water thermohaline indexes. We also investigate this relationship under glacial and interglacial conditions between 7.2 and 32 kyr BP. Ten plankton samples distributed between 32º55' and 26º20'S were selected for the analyses of modern O. universa specimens. Core SIS188 was retrieved at 29º22'S, 47º28'W enabling the analysis of 21 fossil samples. Shell diameter, pore diameter, pore density and porosity were measured using SEM images. Chronology of core SIS188 is based on four AMS 14C ages and the planktonic foraminifera oxygen isotope curve. Planktonic foraminifera relative abundances were converted into SST data using the Modern Analog Technique (MAT). Correlations between the morphometric parameters and temperature and salinity of surface Waters (modern samples) or paleotemperature (fossil samples) were calculated. Morphological characteristics of the analyzed shells allowed to differentiate two morphotypes of O. universa, namely Caribbean and Mediterranean in the studied region. For the Caribbean morphotype, the large pore density showed a negative correlation with both temperature and salinity. For the Mediterranean morphotype, no significant correlations were found. For fossil samples, no significant correlations were found between summer SST (0-50m) and morphometric parameters for the Caribbean or the Mediterranean morphotypes. Possibly, other genotypes do exist in the fossil record, so modern and fossil morphotypes would not have the same behavior. Another explanation for the absence of correlation in fossil samples are errors associated with the SST estimates. Furthermore, fossil samples could represent distinct and more complex oceanographic conditions compared to current configuration, with Plata Plume Water and Brazil Malvinas Confluence migration playing a most significant role in the past. [ABSTRACT FROM AUTHOR]

Abstract Silver ions are among the predominant anthropogenic introduced pollutants in aquatic systems. As silver has effects on species at all trophic levels the community composition in aquatic habitats can be changed as a result of silver stress. The response of planktonic protists to environmental stressors is particularly important as they act both as producers and consumers in complex planktonic communities. Chrysomonad flagellates are of major interest, since this group includes heterotrophic, mixotrophic and phototrophic taxa, and therefore allows analysis of silver stress in organisms with contrasting nutritional strategies independent of a potential taxonomic bias. In a series of lab experiments, we compared the response of different trophic chrysophyte strains to low (5 μg L−1), medium (10 μg L−1) and high (20 μg L−1) nominal Ag concentrations in combination with changes in temperature and light intensity (phototrophs), temperature and food concentration (heterotrophs), or a combination of the above settings (mixotrophs). All tested strains were negatively affected by silver in their growth rates. The phototrophic strains reacted strongly to silver stress, whereas light intensity and temperature had only minor effects on growth rates. For heterotrophic strains, high food concentration toned down the effect of silver, whereas temperatures outside the growth optimum had a combined stress effect. The mixotrophic strains reacted differently depending on whether their nutritional mode was dominated by heterotrophy or by phototrophy. The precise response pattern across all variables was uniquely different for every single species we tested. The present work contributes to a deeper understanding of the effects of environmental stressors on complex planktonic communities. It indicates that silver will negatively impact planktonic communities and may create shifts in their composition and functioning. Graphical abstract Image 1 Highlights • Silver affects chrysomonad growth rates depending on the mode of nutrition. • High food concentrations can tone down the effect of silver in heterotrophics. • Light and temperature influence the effect of silver in phototrophics only slightly. • Mixotrophics react to silver depending on their predominant nutritional mode. Silver ions affect growth rates of flagellate populations depending on their mode of nutrition and thus may cause shifts in the composition and functioning of planktonic communities. [ABSTRACT FROM AUTHOR]

Abstract A novel bioassay is presented that allows for the estimation of the chronic toxicity of contaminants in receiving tropical marine environments. Relevant procedures to identify contaminants of concern and evaluate hazards associated with contamination in these environments have long remained inadequate. The 6-day bioassay is conducted using freshly hatched planktonic larvae of the hermit crab Coenobita variabilis and is targeted at generating environmentally relevant, chronic toxicity data. The developmental endpoint demonstrated consistently high control performance and was validated through the use of copper as a reference toxicant. In addition, the biological effects of aluminium, gallium and molybdenum were assessed. The endpoint expressed high sensitivity to copper (EC 10 = 24 µg L−1) and moderate sensitivity to aluminium (EC 10 = 312 µg L−1), whereas gallium and molybdenum elicited no obvious effects, even at high concentrations (EC 10 > 6000 µg L−1), providing valuable information on the toxicity of these elements in tropical marine waters for derivation of water quality guidelines or testing of compliance limits. Highlights • A novel toxicity bioassay is presented considering development of hermit crab larvae. • The assay generates chronic toxicity data relevant to tropical marine environments. • Chronic toxicity data were generated for copper, aluminium, gallium and molybdenum. • Resulting data can be used by resource managers to establish water quality guidelines. • The assay may be utilized by industry for discharge licence compliance testing. [ABSTRACT FROM AUTHOR]

Abstract To understand the impact of seasonal variability on plankton food web composition in tropical coastal waters, samples were collected from three locations along Tuticorin coastal waters during postmonsoon, summer, and northeast (NE) monsoon seasons. During the NE monsoon, the total suspended matter (TSM) and nutrient concentrations were relatively higher, whereas salinity and plankton (phytoplankton and zooplankton) abundances were lower. Cluster analysis also revealed that the NE monsoon formed into a separate cluster because of the lower phytoplankton abundance caused by higher loads of TSM; this arrests light penetration, thereby resulting in a decrease in plankton abundance. The increase in zooplankton biomass coincided with the decrease in diatoms (p < 0.05), and the increase in cyanobacteria may reflect that grazers food choice has a significant impact on the base of the food web composition. The present study states that the phytoplankton biomass was greatly influenced by seasonality and associated changes rather than the huge supply of nutrient loads. Highlights • Nutrient concentrations and TSM were relatively higher during Northeast monsoon. • Phytoplankton biomass and abundances showed their maximum during nonmonsoon. • Zooplankton is showing great influence on phytoplankton community composition. • Decrease in diatom number was coincided with increase in zooplankton biomass • Seasonality and associated changes altering food web composition. [ABSTRACT FROM AUTHOR]

Abstract To date there is no gold standard for sampling microplastics. Zooplankton sampling methods, such as plankton and Neuston nets, are commonly used to estimate the concentrations of microplastics in seawater, but their ability to detect microplastics is limited by their mesh size. We compared different net-based sampling methods with different mesh sizes including bongo nets (>500 μm), manta nets (>300 μm) and plankton nets (>200 μm and >400 μm) to 1 litre bottle grabbed, filtered (0.45 μm) samples. Concentrations of microplastics estimated using net-based methods were ~3 orders of magnitude less than those estimated by 1 litre grab samples. Some parts of the world with low human populations, such as Ascension Island and the Falkland Islands, lack baseline data on microplastics. Using the bottle grab sampling method we found that microplastic litter was present at these remote locations and was comparable to levels of contamination in more populated coastal regions, such as the United Kingdom. Highlights • Plankton-, bongo- and manta nets underestimate concentrations of microplastics. • Sampling with 1 litre bottles is more effective for capturing smaller microplastics. • Sampling methods with nets are more effective at capturing larger microplastics. • Microplastics are also common in coastal waters of remote location. [ABSTRACT FROM AUTHOR]

Abstract This study explores in plankton samples the abundance, distribution, size, types (fibres and fragments), colours of the microplastics (MPs) and its relation with the characteristics of the plankton (size and morphology) of the Río de la Plata estuary. Water samples were collected in triplicate in freshwater-mixohaline tidal zone of the estuary, in ten sampling sites located along 150 km of coast, in two periods (September–November 2016 and April–June 2017). The results revealed the presence of MPs in all the samples analysed, with a dominance of fibres and sizes >500 ≤ 1000 μm, and blue colour being more frequent. The MPs distribution was significantly different among sampling sites, being more abundant in the most urbanized sites, sewage discharges and near the maximum turbidity front. The mean density, in the two samplings analysed, were 164 and 114 MPs m−3. The fibres amount was significantly different among sites. The MPs integrated a planktonic community dominated by pico-microphytoplankton, mainly conformed by filaments/chains and solitary forms and by micro-mesozooplankton. The comparative analysis of plankton and MPs demonstrated that a fraction of the latter showed a frequency range of size that coincides with the most common sizes of plankton (≤500 μm). The mean percentage of MPs items in relation to zooplankton was 0.36% (sampling 1) and 1.20% (sampling 2) and for phytoplankton was 0.0002% (sampling 1) and 0.0005% (sampling 2). The correlations between the MPs concentration and habitat quality (IHRPlata index) were statistically significant, on the contrary correlations between the MPs concentration and measured environmental variables were not found. The findings of this study emphasises the need for a better treatment of urban waste, which would contribute to reducing the entry of this pollutant into the ecosystem. The presence of microplastics in plankton samples on the coast of the Río de la Plata estuary. Graphical abstract Image Highlights • The mean of microplastics (MPs) in the water column was 139 MPs m−3. • The most frequent MPs sizes were >500 ≤ 1000 μm, with a higher fibres concentration. • The MPs were more abundant in the sites near cities, sewage effluents and the turbidity front. • A fraction of MPs showed a frequency range of size that coincides with the most common sizes of plankton. [ABSTRACT FROM AUTHOR]

Various imaging systems are producing complex data that improve our understanding of physical and biological coupling in the ocean. In-situ shadowgraph imaging is one sampling technique that captures detailed biological information for a wide range of plankton with differing body compositions (e.g., gelatinous to crustacean) in their natural orientations, as well as small-scale physical changes. When combined with rapidly advancing computer vision methods and high-resolution oceanographic observations, shadowgraph imagery holds promise for generating new discoveries in ocean science that are only limited by our creativity in asking new questions. [ABSTRACT FROM AUTHOR]

Abstract The microplastic studies in the world is increasing, reflecting concern about its effects on the ecosystem. The same happened in Brazil, especially in the last six years, but few places were monitored. Thus, a literature review was conducted to collect data on microplastic pollution in Brazilian aquatic ecosystems, analyzing this pollutant in samples of sandy sediments, plankton and other invertebrates and vertebrates. As results, we highlight the following points: 56% of the studies were published in the Journal Marine Pollution Bulletin; collaborative and independent studies presented the same number; the Brazilian Northeast and Southeast were the most studied areas; the investigation of microplastics associated with biota was highlighted (46% of studies); only one study was conducted in a freshwater environment. Based on this review, we identified the subjects that would be more studied in researches in the Brazilian environment about microplastics. The monitoring of microplastics must be continuous to verify the impacts of this material and extend the understanding of this problem. Highlights • Microplastics have been detected in several systems in Brazil. • The investigation of microplastics associated to biota was more prevalent. • Only one study was conducted in a freshwater environment. • Priorities for microplastic research in Brazil inland water systems are proposed. [ABSTRACT FROM AUTHOR]

It is widely understood that microplastics (MPs) are ubiquitous in the marine environment yet less is known about MP abundance in freshwater rivers, particularly those of the western United States. This study documents MP pollution along the Snake River (∼1735 km) and from its confluence with the Columbia River to the Pacific Ocean. Grab and plankton net samples (mesh size 100 μm) were collected from the top 25 cm of surface water every 80.5 river km. MPs were identified if they met visual criteria and were verified with the hot needle test. A small representative subset of MPs from the net samples (16.7%) were selected based on appearance for micro-Raman spectroscopy in effort to provide examples of polymer types found in this study. Seventy-five percent of grab samples and 92.8% of net samples contained MPs, with concentrations ranging from 0 to 5.405 MP L −1 and 0 to 0.014 MP L −1 (0 to 13.7 MP m −3 ), respectively. The majority of fragments, films and beads were between 100 μm and 333 μm. This study identifies potential hotspots of MP pollution along the Snake and Lower Columbia rivers and prioritizes areas where more intensive sampling is needed. Sites with low flow or those further down river had higher numbers and the top two hotspots were located in areas with low population density but high agricultural use. Monitoring MP abundance in freshwater systems is important for establishing baseline levels of MP pollution and can direct laboratory toxicology studies in using more environmentally relevant concentrations for a better indication of how MP pollution affects ecosystems. [ABSTRACT FROM AUTHOR]

Abstract As part of its commitment to the EU Marine Strategy Framework Directive (MSFD) OSPAR has developed three plankton indicators of Good Environmental Status (GES) for pelagic habitats in the Northeast Atlantic. In coming years, implementation of the MSFD will extend into the Arctic, requiring the application of pelagic habitat indicators in the region. Because plankton communities and monitoring effort are spatially variable, applicability to the Arctic of existing indicators must be assessed. A meta-analysis is applied to the Northeast Atlantic pelagic habitat indicators to establish their ecological applicability and relevance to Arctic marine ecosystems and their implementability using existing national monitoring effort. To identify gaps and potential improvements in the OSPAR indicators, two gap analyses were conducted. The first considered the Northeast Atlantic OSPAR-adopted indicators and existing plankton indicators currently employed by Arctic nations. The second assessed the minimum data attributes required to implement existing OSPAR indicators compared to existing national plankton monitoring effort by OSPAR Arctic contracting parties. Existing Northeast Atlantic pelagic habitat indicators were found to be ecologically applicable to the Arctic, primarily due to flexibility of the plankton lifeforms and biodiversity indices indicators, that allow selection of regionally relevant lifeform pairs or species for assessment. However, current national monitoring programmes were found insufficient to support their implementation. Additional regionally-specific indicators, such as for sympagic phytoplankton and sea-ice biota, are worthy of consideration. Budgetary constraints and a lack of year-round sampling and long-term datasets were found to be key limitations in the implementation of plankton indicators for establishing GES. Highlights • NE Atlantic OSPAR pelagic habitat indicators are ecologically applicable to Arctic. • The indicators are not implementable under current national monitoring programmes. • Key prohibitive factors are lack of funding and low frequency of sampling. [ABSTRACT FROM AUTHOR]

Abstract The marine oligotrich ciliate Strombidium sulcatum , the best known marine oligotrich of the marine microozoplankton, was first cultured in Villefranche-sur-Mer 35 years ago. Cultures were maintained from 1983 to 2003 and used in 22 studies investigating a very wide variety of questions. Here we review the major findings of these studies and underline their contributions to our knowledge of planktonic ciliate ecology and microbial ecology in general. We conclude with the observation that while ecophysiology has apparently fallen out of fashion, culture work will likely return as an invaluable resource in our present 'omics' era. [ABSTRACT FROM AUTHOR]

Plankton plays a prominent role in the bioaccumulation of mercury (Hg). The MERITE-HIPPOCAMPE campaign was carried out in spring 2019 along a north-south transect including coastal and offshore areas of the Mediterranean Sea. Sampling of sea water and plankton by pumping and nets was carried out in the chlorophyll maximum layer. Two size-fractions of phytoplankton (0.7–2.7 and 2.7–20 μm) and five of zooplankton (between 60 and >2000 μm) were separated, and their total mercury (THg) and monomethylmercury (MMHg) contents were measured. Bioconcentration of THg was significantly higher in the smallest phytoplankton size-fraction dominated by Synechococcus spp. The bioaccumulation and biomagnification of MMHg in zooplankton was influenced by size, food sources, biochemical composition and trophic level. MMHg was biomagnified in the plankton food web, while THg decreased toward higher trophic levels. Higher MMHg concentrations were measured in oligotrophic areas. Plankton communities in the Southern Mediterranean Sea had lower MMHg concentrations than those in the Northern Mediterranean Sea. These results highlighted the influence of environmental conditions and trophodynamics on the transfer of Hg in Mediterranean plankton food webs, with implications for higher trophic level consumers. • Highest THg bioconcentration was highlighted in picoplankton. • MMHg biomagnified while THg decreased along the plankton food web. • MMHg bioaccumulated and biomagnified in zooplankton. • Highest zooplankton MMHg concentrations were observed in oligotrophic areas. [ABSTRACT FROM AUTHOR]