Harpacticoid Copepods Research Articles

Horizontal and Vertical Distribution and Abundance of Zooplankton around the Swatch-of-No-Ground of Northern Bay of Bengal

This study assessed horizontal and vertical distribution and abundance of zooplankton community in water samples collected from 26 stations at a depth of 0 to 250 m of the northern Bay of Bengal. A total of 55 zooplankton species were identified where Copepod was 72.41% and Ciliophora was 8.62%. Among the Copepod, 48%, 40% and 12% of species were Calanoid, Cyclopoid and Harpacticoid Copepod, respectively. This study also found 2 species of Decapod, 2 species of Rotifer, 2 species of Cladocera, 1 species of Chaetognatha and 1 species of Stomatopoda. Spatial distribution of zooplankton species was varied from station to station and cruise to cruise. Maximum 23,868 individuals of zooplanktons were recorded in cruise 2, whereas the lowest number (758 individuals) was found in cruise 4. Zooplankton abundance was ranged between 18 to 22,500 cells/L in all cruises, whereas the highest abundance was found in cruise 2 and the lowest was recorded in cruise 4. The highest abundance (37,310 individuals) was documented at surface water and the lowermost number of zooplankton (10 individuals) was recorded at 100 m depth. This study showed negative correlation between zooplankton abundance and water depth. The results of the current study might help to understand zooplankton abundance and distribution in the northern Bay of Bengal and will use as a baseline study for further research. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 10(2), 2021, P 1-8

Dynamics of epibenthic copepods in relation to environmental factors and phytoplankton abundance in tropical river, estuarine and coastal environments

Changes in epibenthic copepod populations markedly affect the population of benthic dwelling animals in rivers, estuaries and marine ecosystems. Unfortunately, studies focusing the environmental influence on the structure of epibenthic copepods are lacking. This study addresses the deficit of information focusing the environmental factors that affect the structure of epibenthic copepods in various lotic environments. The copepods community and environmental variables in water 0.3 m above the bottom of four areas (from 10 km upstream of the Kuantan River mouth to 5 km offshore) were studied monthly over one-year. The study area is characterised by a hot equatorial climate with the monsoon (more-rainy summer, October–March) and the non-monsoon (less-rainy summer, April–September). Totally forty-three species of copepods on thirteen groups were recorded, with harpacticoid copepod groups being dominant in all sampling zones except the upstream zone, where freshwater copepods were dominant and harpacticoid copepods were absent. The total abundance of copepods was greater at the coast and estuary than at the river. Phytoplankton density, salinity, total suspended solids (TSS) and dissolved oxygen (DO) significantly influenced the abundance of epibenthic copepod groups, but their influence on copepods was zone-specific. At the coastal and the estuarine zones, harpacticoid copepod groups were positively influenced by the abundance of phytoplankton, whereas the other copepod groups were negatively influenced by the TSS. The influence of TSS on cyclopoid and calanoid copepods was dependent on the density of phytoplankton with a higher density reducing the impact of TSS. At the downstream, harpacticoid copepod groups were positively influenced by the abundance of phytoplankton, DO and salinity while the other copepod groups were positively influenced by DO and salinity and negatively influenced by TSS. At the upstream, freshwater copepod groups were positively influenced by the DO concentration and negatively influenced by the salinity while, other copepod groups were positively influenced by both DO and salinity. Other environmental variables had a weak and insignificant influence on the densities of observed copepod groups. Both monsoon and non-monsoon seasons equally influenced the observed copepod groups. The observed results need to be regularly monitored to changing tropical environments for better elucidating the ecology of various groups of epibenthic copepods associated with the climate change and various anthropogenic activities.

Intensive production of the harpacticoid copepod Tigriopus californicus in a zero-effluent \u2018green water\u2019 bioreactor

Aquaculture is looking for substitutes for fishmeal and fish oil to maintain its continued growth. Zooplankton is the most nutritious option, but its controlled mass production has not yet been achieved. In this context, we have developed a monoalgal ‘green water’ closed-loop bioreactor with the microalgae Tetraselmis chui that continuously produced the harpacticoid copepod Tigriopus californicus. During 145 days of operation, the 2.2 m3 bioreactor produced 3.9 kg (wet weight) of Tigriopus with (dry weight) 0.79 ± 0.29% eicosapentaenoic acid (EPA), 0.82 ± 0.26% docosahexaenoic acid (DHA), 1.89 ± 0,60% 3S,3’S-astaxanthin and an essential amino acid index (EAAI) of 97% for juvenile Atlantic salmon. The reactor kept the pH stable over the operation time (pH 8.81 ± 0.40 in the algae phase and pH 8.22 ± 2.96 in the zooplankton phase), while constantly removed nitrate (322.6 mg L−1) and phosphate (20.4 mg L−1) from the water. As a result of the stable pH and nutrient removal, the bioreactor achieved zero effluent discharges. The upscaling of monoalgal, closed-loop ‘green water’ bioreactors could help standardize zooplankton mass production to supply the aquafeeds industry.

Importance of nonindigenous harpacticoids (Crustacea: Copepoda) decrease with depth in Lake Ontario

Harpacticoid copepods can be a substantial component of the meiobenthic community in lakes and serve an ecological role as detritivores. Here we present the first species-level lake-wide quantitative assessment of the harpacticoid assemblage of Lake Ontario with emphasis on the status of nonindigenous species. Additionally, we provide COI-5P sequences of harpacticoid taxa through Barcode of Life Data System (BOLD). Harpacticoids were collected at depths from 0.1 to 184 m and from a range of substrates from August to September 2018 as part of the Cooperative Science and Monitoring Initiative (CSMI) offshore benthic survey. Twenty-six meiobenthic samples were analyzed using microscopy for community composition analysis of harpacticoids. We found thirteen indigenous and three nonindigenous species of harpacticoid, with the introduced species dominating at shallow depths. The community transitioned from nonindigenous to indigenous species dominance as depth increased. Nonindigenous species accounted for 79% of the community (by abundance) at depths <20 m, 55% from 20 to 40 m, and only 24% at depths >40 m. The nonindigenous species encountered included the first detections of Schizopera borutzkyi (Monchenko, 1967) and Heteropsyllus nunni (Coull, 1975) from Lake Ontario. S. borutzkyi was the most abundant harpacticoid species in the lake, approaching a maximum density of 50,000/m2 and a lake-wide average density of 7,900/m2. Numerically important indigenous species included Bryocamptus nivalis (Willey, 1925), Canthocamptus robertcokeri (Wilson, 1958), Canthocamptus staphylinoides (Pearse, 1905), and Moraria cristata (Chappuis, 1929). The prevalence of nonindigenous harpacticoids in the meiobenthos of Lake Ontario suggests further investigations of Great Lakes meiofauna communities are warranted.

Morphological revision of phytal red-stripe Eudactylopus fasciatus Sewell, 1940 (Crustacea, Copepoda, Harpacticoida) from Bangaram Island, Lakshadweep, India

Specimens of the harpacticoid copepod Eudactylopus fasciatus Sewell, 1940 were found in plankton samples taken from Lakshadweep, India. In this study, E. fasciatus is redescribed on several additional distinct morphological characters along with the original description dating back to 1940 (Sewell, 1940). The most important features of E. fasciatus from Bangaram Island are the external coloration pattern with eight longitudinal bands, additional numbers of setae on the 1st, 2nd, 3rd, and 7th segments of the A1, and the modified saber-shaped sexually dimorphic second endopod segment of the male P2 with a bud-like structure. The illustrated redescription and a taxonomic key for the identification of all the species of the genus Eudactylopus are also provided.

Comparative characteristics of harpacticoids species diversity in contact zones of the northwestern part of the Black sea

In the article there are research results of comparative analysis of the species structure of crustaceans Harpacticoida (Copepoda) in the meiobenthos of different contact zones in the north-western part of the Black Sea. The fauna of harpacticoid copepods of contour biotopes in NWBS during the study period numbered 76 species belonging to 46 genera from 23 families. The largest number of species of harpacticoid copepods (44 species) was registered on the pelocontour. The lithocontour and psamocontour had 39 and 34 species of harpacticoids, respectively. The smallest number of species (19 species) of harpacticoid copepods was registered on the potamo contour. Cluster analysis of the harpacticoid species number in contour biotopes showed that the fauna of the potamocontour is similar to other contours by only 20.07 %. The similarity in the species composition of the peloton and lithocontour is 52.27 %, and the species diversity of the potamocontour harpacticoids is similar to them by 42.85 %. Common to all contour habitats are 6 species: Ameira parvula parvula, Dactylopusia tisboides, Ectinosoma melaniceps, Harpacticus flexus, Harpacticus littoralis, Laophonte elongata elongata. Vegetation of the OMR lithocontour had the largest number of species (35 species, which is 46 % of the total number of species), and near 24 species of snakes were noted. Almost the same number of species was observed at the stations remote from the shore and near the shore. The smallest number of species was noted on the interstitial supralittoral of the psamocontour, and their number was almost three times greater in the upper sublittoral. The Pelocontour of Yagorlytska and Tendrivska counted 34 species of harpacticoid copepods, and in the OMR – 21 species. The coastal part of the potamocontour is characterized by the greatest species diversity (Margalef index – 1.3±0.1, Shannon index – 1.7±0.3; Simpson index – 0.8±0.05).

A new species of Esola Edwards, 1891 (Crustacea, Copepoda, Harpacticoida, Laophontidae) from the Caribbean coast of Colombia.

A new species of the harpacticoid copepod genus Esola is described from specimens collected in Rodadero Beach, on Gaira Bay, on the Caribbean coast of Colombia. The species, E.wellsisp. nov., is described, illustrated, and com­pared with its congeners. Esolawellsisp. nov. differs from its known congeners in details of the armature of legs 1–4. It most closely resembles E.bulbifera (Norman, 1911) in the armature formula of P1–P5 but differs from the latter in several respects, including the female antennule segmentation (7-segmented in E.bulbifera but distinctly 6-segmented in E.wellsisp. nov.) and in the shape and size of the male P3ENP2 apophysis, among other characters. This is the second species of the genus known from the Caribbean and the second record of Esola in the Northwestern Tropical Atlantic. The genus now contains eight species. A key to the known species of the genus is also included.

Structure and Trophic Niches in Mobile Epifauna Assemblages Associated With Seaweeds and Habitats of Syngnathid Fishes in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberia)

Syngnathids are vulnerable fishes closely associated with seaweeds and seagrass, which provide shelter and food resources. Even though most syngnathids commonly feed on small crustaceans, the feeding regimes may differ depending on the species and prey availability. This is the first monitoring study to explain syngnathid abundances and dietary regimes within macroalgal beds in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberian Peninsula). We sampled the epifaunal assemblages in seaweed communities dominated by the canopy-forming macroalgaeGongolaria baccataandCodiumspp. seasonally during 2 years. The epifaunal structure was mostly represented by harpacticoid copepods, amphipods (especially gammarids) and gastropods. Epifauna exhibited low plant-host specificity and a higher dominance of amphipods on the more structurally complex macroalgaeG. baccata.The epifaunal assemblages and syngnathid specimens were assessed for trophic structure using stable isotopes (δ13C and δ15N). The three syngnathids (Hippocampus guttulatus,Syngnathus acus, andEntelurus aequoreus) inhabiting Cíes Archipelago were sympatric. They occupied highly similar trophic positions (TPs), but differed in niche size, in such a way that the snake pipefishE. aequoreuswould likely feed on smaller prey. The assessment of the feeding regime in the dominant great pipefishS. acusrevealed that amphipods mostly contributed to bulk diet, followed by isopods, carideans, and copepods, whereas mysidaceans were not highly consumed. Seasonal changes in both epifaunal structure and syngnathids abundance confirmed that syngnathids are seasonal residents in Cíes Archipelago, migrating to other areas in autumn when the seaweed cover is drastically reduced and the epifaunal structure modified. This study showed the importance ofGongolariaassemblages in Cíes Archipelago, providing rich dietary sources and potentially contributing to higher abundances and diversity of syngnathids. Ongoing cover reduction inGongolariaassemblages in certain regions (e.g., Mediterranean) should be considered a potential ecological concern for syngnathids and accompanying fauna, requiring further investigations.

Sea-ice associated carbon flux in Arctic spring

The Svalbard region faces drastic environmental changes, including sea-ice loss and “Atlantification” of Arctic waters, caused primarily by climate warming. These changes result in shifts in the sea-ice-associated (sympagic) community structure, with consequences for the sympagic food web and carbon cycling. To evaluate the role of sympagic biota as a source, sink, and transmitter of carbon, we sampled pack ice and under-ice water (0–2 m) north of Svalbard in spring 2015 by sea-ice coring and under-ice trawling. We estimated biomass and primary production of ice algae and under-ice phytoplankton as well as biomass, carbon demand, and secondary production of sea-ice meiofauna (&amp;gt;10 µm) and under-ice fauna (&amp;gt;300 µm). Sea-ice meiofauna biomass (0.1–2.8 mg C m–2) was dominated by harpacticoid copepods (92%), nauplii (4%), and Ciliophora (3%). Under-ice fauna biomass (3.2–62.7 mg C m–2) was dominated by Calanus copepods (54%). Appendicularia contributed 23% through their high abundance at one station. Herbivorous sympagic fauna dominated the carbon demand across the study area, estimated at 2 mg C m–2 day–1 for ice algae and 4 mg C m–2 day–1 for phytoplankton. This demand was covered by the mean primary production of ice algae (11 mg C m–2 day–1) and phytoplankton (30 mg C m–2 day–1). Hence, potentially 35 mg C m–2 day–1 of algal material could sink from the sympagic realm to deeper layers. The demand of carnivorous under-ice fauna (0.3 mg C m–2 day–1) was barely covered by sympagic secondary production (0.3 mg C m–2 day–1). Our study emphasizes the importance of under-ice fauna for the carbon flux from sea ice to pelagic and benthic habitats and provides a baseline for future comparisons in the context of climate change.

On some deep-sea Stenheliinae from the Gulf of California and the west coast of the Baja California Peninsula (Mexico): Wellstenhelia euterpoides sp. nov., and Wellstenvalia wellsi gen. et sp. nov. (Copepoda: Harpacticoida: Miraciidae).

At present, only 11 species of harpacticoid copepods have been described from the deep sea of the Gulf of California and the west coast of the Baja California Peninsula. These efforts had until recently been focused exclusively on the families Ameiridae Boeck, Argestidae Por, and Rhizothrichidae Por. Preliminary analyses revealed also an important contribution of the subfamily Stenheliinae Brady (Miraciidae Dana) to the overall species richness and diversity of deep-sea benthic copepods from the west coast of the Baja California Peninsula, and the central and southern Gulf of California. One new species of the genus Wellstenhelia Karanovic Kim, 2014, We. euterpoides sp. nov., and one new genus and species, Wellstenvalia wellsi gen. et sp. nov., are herein described from sediment samples taken at eight sampling stations in the west coast of the Baja California Peninsula and in the central and southern Gulf of California. Wellstenhelia euterpoides sp. nov. seems to be closely related to We. euterpe Karanovic Kim, 2014 with which it shares the reduced armature complement of the baseoendopod of the female fifth leg. The so far monotypic genus Wellstenvalia gen. nov. was found to be closely related to Muohuysia zdikmen, 2009 and Wellstenhelia. Some comments on the relationships between the new genus proposed here and other stenheliin genera and species are provided as a contribution towards the monophyly of the subfamily.

Systematics and Taxonomy of Harpacticoid Copepods—A Commemorative Volume in Honour of Prof. John J.B. Wells (Table of contents)

Systematics and Taxonomy of Harpacticoid Copepods—A Commemorative Volume in Honour of Prof. John J.B. Wells (Table of contents)

Deep sea without limitsfour new closely related species of Emertonia Wilson, 1932 (Copepoda: Harpacticoida: Paramesochridae) show characters with a world-wide distribution.

The large-scale dispersal of deep-sea harpacticoid copepods is an increasing focus for ecological studies. A fundamental prerequisite for monitoring and explaining their geographical distribution is precise descriptions of their morphology. Four new, closely related species of the family Paramesochridae (Copepoda, Harpacticoida) were found in the deep sea of the Pacific (San Diego Trough and off Chile), the Atlantic Ocean (Porcupine Abyssal Plain and Angola Basin), and the Atlantic and Indian Ocean sectors of the Southern Ocean (Weddell Sea and off Crozet Island). The discovery of Emertonia berndi sp. nov., E. hessleri sp. nov., E. ilse sp. nov., and E. serrata sp. nov. increases the number of known deep-sea species in this genus to ten. The new species are placed in Emertonia Wilson, 1932 because of their one-segmented endopods on the second and third swimming legs. The presence of a two-segmented endopod on the fourth swimming leg allocates them to the andeep-group within this genus. The four species can be distinguished from their congeners by the strongly serrated spines on the exopods of their swimming legs and an outwardly directed flexible seta on the exopod of the fifth leg. It is conveivable that these two specific characters evolved only once in the genus Emertonia. Their apparently cosmopolitan distribution covers thousands of kilometres and spans all major oceans. This biogeographical pattern may be explained by resuspension events followed by passive transport by benthic currents. Discrepancies in their dispersal ranges may be a result of changing geological and oceanographic boundaries.

Systematics and Taxonomy of Harpacticoid CopepodsA Commemorative Volume in Honour of Prof. John J.B. Wells (Title).

Systematics and Taxonomy of Harpacticoid CopepodsA Commemorative Volume in Honour of Prof. John J.B. Wells (Title).

Epibiont Assemblages on Nesting Hawksbill Turtles Show Site-Specificity in the Persian Gulf

Sea turtle epibionts can provide insights into the hosts' habitat use. However, at present, there is a lack of information on sea turtle epibiont communities in many locations worldwide. Here, we describe the epibiont communities of 46 hawksbill turtles (Eretmochelys imbricata) in the Persian Gulf. Specifically, we sampled 28 turtles from the Dayyer-Nakhiloo National Park (DNNP) in the northern Gulf and 18 turtles from Shibderaz beach in the Strait of Hormuz. A total of 54 macro, meio, and micro-epibiont taxa were identified, including 46 taxa from Shibderaz and 29 taxa from DNNP. The barnacles Chelonibia testudinaria and Platylepas hexastylos, as well as harpacticoid copepods and Rotaliid foraminifers, had the highest frequency of occurrence found on almost all turtle individuals. Harpacticoids were the most abundant epizoic taxa (19.55 ± 3.9 ind. per 9 cm2) followed by forams (Quinqueloculina spp.: 6.25 ± 1.5 ind. per 9 cm2 and Rotaliids: 6.02 ± 1.3 ind. per 9 cm2). Our results showed significant differences between the study sites in the composition of micro and macro-epibiont communities found on hawksbill turtles. We speculate that the differences in epibiont communities were largely influenced by local environmental conditions.

The Discovery and Preliminary Geological and Faunal Descriptions of Three New Steinahóll Vent Sites, Reykjanes Ridge, Iceland

During RVMS Merianexpedition MSM75, an international, multidisciplinary team explored the Reykjanes Ridge from June to August 2018. The first area of study, Steinahóll (150–350 m depth), was chosen based on previous seismic data indicating hydrothermal activity. The sampling strategy included ship- and AUV-mounted multibeam surveys, Remotely Operated Vehicle (ROV), Epibenthic Sledge (EBS), and van Veen grab (vV) deployments. Upon returning to Steinahóll during the final days of MSM75, hydrothermal vent sites were discovered using the ROV Phoca (Kiel, GEOMAR). Here we describe and name three new, distinct hydrothermal vent site vulnerable marine ecosystems (VMEs); Hafgufa, Stökkull, Lyngbakr. The hydrothermal vent sites consisted of multiple anhydrite chimneys with large quantities of bacterial mats visible. The largest of the three sites (Hafgufa) was mapped, and reconstructed in 3D. In total 23,310 individual biological specimens were sampled comprising 41 higher taxa. Unique fauna located in the hydrothermally venting areas included two putative new species of harpacticoid copepod (Tisbesp. nov. andAmphiascussp. nov.), as well as the spongeLycopodina cupressiformis(Carter, 1874). Capitellidae Grube, 1862 and Dorvilleidae Chamberlin, 1919 families dominated hydrothermally influenced samples for polychaetes. Around the hydrothermally influenced sites we observed a notable lack of megafauna, with only a few species being present. While we observed hydrothermal associations, the overall species composition is very similar to that seen at other shallow water vent sites in the north of Iceland, such as the Mohns Ridge vent fields, particularly with peracarid crustaceans. We therefore conclude the community overall reflects the usual “background” fauna of Iceland rather than consisting of “vent endemic” communities as is observed in deeper vent systems, with a few opportunistic species capable of utilizing this specialist environment.

High biomass and productivity of epifaunal invertebrates living amongst dead coral

Climate change is transforming coral reef structures, with important yet largely unknown consequences for reef food webs. Crustaceans, molluscs, polychaetes, and other small motile invertebrates living as epifauna on coral habitats represent an essential trophic link between primary producers and a diverse and abundant invertivorous fish fauna. Here, we investigate variation in assemblages of motile epifaunal invertebrates on live coral and dead coral heavily overgrown by turf algae. Sampling was conducted 2–3 years following mass bleaching within the study region at four locations broadly spanning the distribution of corals on the eastern seaboard of Australia—along the northern and central Great Barrier Reef, and, adjacent to the central east coast, the Solitary Islands and offshore Elizabeth and Middleton Reefs (> 2000 km total distance). Epifaunal assemblages differed significantly between live and dead ‘turf-covered’ coral habitats, with overall density, biomass, and productivity of epifauna more than an order of magnitude greater on dead than on live coral. The size structure and composition of assemblages also differed: turf-covered dead coral supported greater abundances of small animals than live coral, notably harpacticoid copepods, while live coral assemblages had proportionally greater abundances of larger decapods. A ten-fold increase in secondary productivity of motile invertebrates is predicted as live corals are replaced by turf-covered dead coral, however, this productivity will predominantly be available as small harpacticoid copepod prey (size range: 0.125–0.25 mm). Associated flow-on effects through reef food webs are likely, as changes to epifauna will directly affect invertivore communities, which in turn potentially influence larger carnivores and other functional groups.

Analysing individual growth curves for the copepod Tigriopus brevicornis, while considering changes in shape

Understanding growth and development over ontogeny, and the effects of stressors on life history, requires bioenergetic analysis, for example using models based on dynamic energy budget theory. Such analyses require precise and accurate determination of the animal's biomass or biovolume over time. Automated imaging offers great advantages by allowing size measurements at a high temporal resolution and the possibility to follow individual animals, thus providing detailed growth trajectories as well as handles on inter-individual variation in growth. Here we report on a re-analysis of images from a life-cycle experiment with the coastal harpacticoid copepod Tigriopus brevicornis. Biovolume was estimated by approximating the organism's shape by a generalised ellipsoid. This analysis confirmed, rather unsurprisingly, that the moult from the last naupliar to the first copepodite stage is accompanied by a major change in shape. However, within the naupliar and copepodite stages, more gradual elongation was observed. These changes in shape imply that total body length is a poor proxy for body size throughout the developmental stages, and is therefore not suitable for bioenergetic analysis. Volumetric length (cubic root of estimated body volume) is far more appropriate. Interestingly, growth ceases for some 1.5 days around the moult to the first copepodite stage. Such a growth stop was not observed in earlier studies of several other copepod species. Furthermore, the growth rate of the copepodites exceeded that of the nauplii. These complexities in the life history of T. brevicornis pose challenges for bioenergetic analysis that will require determination of additional traits (e.g., feeding and respiration rates) to unravel.

Changes in the Development and Reproductive Output of Nitokra lacustris pacifica (Crustacea: Copepoda) Yeatman, 1983 Under Short and Long Term Exposure to Synthetic and Biodegradable Microbeads

Microplastics have become a significant problem in the marine environment where a wide range of marine organisms can ingest them. Biodegradable plastics or bioplastics, which are now being widely sourced as an alternative to conventional non-biodegradable plastics, are also known to breakdown into microparticles. This study aims to investigate the interaction between two types of microbeads towards the reproductive and development functions of the harpacticoid copepod, Nitokra lacustris pacifica. Polystyrene (PS) microspheres were used as the synthetic treatment, while microbeads produced from bacterial polyhydroxyalkanoates (PHA) copolymer were used as the biodegradable treatment. Exposure to microplastics at concentrations of ~ 700 microbeads mL−1 exhibited a significant reduction in algal (Nannochloropsis sp.) ingestion. No differences were observed egg production rate (9.3–10.5 eggs fem−1 day−1), but nauplius production was significantly reduced in PS microbead treatment (40%). Development time of N. lacustris pacifica from egg to adult in control (Nannochloropsis sp.) and PHA microbead treatments was significantly shorter (10.7 and 11.2 days, respectively) than in PS microbead treatment (14 days). Similarly, during the extended exposure, no differences were observed in the egg production rate, but nauplius production was significantly affected ( 60%).

Variability in Toxicity of Plastic Leachates as a Function of Weathering and Polymer Type: A Screening Study with the Copepod Nitocra spinipes.

AbstractThe production and use of plastic over many decades has resulted in its accumulation in the world's oceans. Plastic debris poses a range of potential risks to the marine environment and its biota. Especially, the potential hazards of small plastic debris and chemicals associated with plastic have not been extensively studied. When buoyant plastic is exposed to ultraviolet radiation, it will slowly degrade and leach chemicals into surrounding waters. These leachates can include additives, sorbed organic pollutants, and degradation products of the plastic polymers. While most hazard assessments have focused on studying adverse effects due to the uptake of plastic, toxicity studies of the leachates of plastics are less common. To begin to address this knowledge gap, we studied the acute toxicity of leachates from diverse plastics in the harpacticoid copepod Nitocra spinipes. Our results show that leachates caused a higher toxicity after plastic was exposed to ultraviolet light compared to leaching in darkness. We observed differences in toxicity for different polymer types: polyvinyl chloride and polypropylene resulted in the most toxic leachates, while polystyrene and poly[ethylene terephthalate] were least toxic. Furthermore, we observed increased toxicity of leachates from some plastics that had been weathered in the real marine environment compared to matching new materials. Our results indicate that both weathering condition and polymer type influence the toxicity of plastic leachates.

What is the impact of urban development and thermokarsting on arctic tundra pond zooplankton communities?

Human development and warming in the Arctic are increasingly putting new pressures on the abundant freshwater ecosystems in the region. In particular, recent and rapid expansion of thermokarst ponds in permafrost regions has been associated with these stresses. Our goal was to examine the relative impacts of pond enrichment by urban encroachment and thermokarsting, compared to relatively unimpacted regions, on the environmental conditions and zooplankton communities of tundra ponds near Utqiaġvik, AK, USA. Both urban ponds and thermokarst ponds were found to have substantially different environmental conditions, as well as distinctive zooplankton communities relative to reference sites. Thermokarst ponds presented an environment rich in DOC and nutrients (N, P, and Si) and phytoplankton biomass. Enrichment by nutrients and DOC in thermokarst ponds led to significantly greater zooplankton abundance composed largely of Daphnia middendorffiana (66 individuals L−1) and cyclopoid copepods (65 individuals L−1). Urban ponds had moderate nutrient levels, with elevated benthic algal biomass. These ponds had intermediate numbers of D. middendorffianna (14 individuals L−1), as well as significantly higher numbers of diaptomid copepods (8 individuals L−1) and chydorids (11 individuals L−1), as compared to one or both reference regions. The two reference regions [Barrow Environmental Observatory (BEO) and International Biological Program (IBP)] had consistently lower nutrient concentrations, algal levels, and zooplankton abundances (less than 3 individuals L−1). Finally, harpacticoid copepods and Bosmina longirostris were new records for the zooplankton in the region. Further collections are required to determine the drivers for these new observations. These results identify the large potential relative contributions of urban inputs and thermokarsting to enrichment of Arctic aquatic ecosystems and point to thermokarsting, which will likely increase with warming, as a major contributor to change in these systems.