Plankton Diversity Research Articles

Plankton assessment across the distribution of West African hake and tuna based on eDNA metabarcoding

The richness of plankton communities determines the fish productivity in the ocean, including important resources that rely on extractive fisheries, such as hakes (genus Merluccius) and tunas (genus Thunnus). Their preys forage on zooplankton, and the latter feed on phytoplankton. Inventories of plankton communities for scientific advice to sustainable fishing are essential in this moment of climate change. Plankton is generally inventoried using conventional methodologies based on large water volumes and visual morphological analyses of samples. In this study, we have employed metabarcoding on environmental DNA (eDNA) samples extracted from small water volumes for plankton inventory from twelve distant sampling stations in the East Atlantic Ocean. Zones rich in hake and tuna prey were detected from eDNA, and multivariate multiple regression analysis was able to predict those zones from diatom-based indices and planktonic diversity based on functional groups. Salinity was negatively correlated with the proportion of diatoms in phytoplankton, highlighting expected impacts of current global change on marine plankton communities. The results emphasise the importance of the plankton richness for fish productivity and support the utility of environmental DNA as a tool to monitor plankton composition changes.

Taxonomic composition and ecological and geographical characteristics of phytoplankton of Kulundinsky Lake (Altai Territory)

The results of long-term studies of the taxonomic and ecological-geographical diversity of phytoplankton of Kulundinsky Lake are presented. 192 taxa of algae and cyanobacteria of 7 divisions, 15 classes, 38 orders, 63 families, 102 genera were identified in the plankton communities. The taxonomic spectrum is dominated by cyanobacteria and greens, with a significant participation of diatoms. The basis of plankton diversity consists of widespread representatives of the Holarctic kingdom (cosmopolitan and boreal forms). In relation to the salinity and temperature of the water, indifferents predominate, to the active reaction of the medium - indifferents and alkaliphiles. The share of indicator species of saprobity of the aquatic environment is 42.7 %. в -mesosaprobes predominate among the indicators of saprobity.

Composition, Abundance and Diversity of Plankton in Hand-Dug Wells in Ikpe Community, Akwa Ibom State, Nigeria

Composition, Abundance and Diversity of Plankton in Hand-Dug Wells in Ikpe Community, Akwa Ibom State, Nigeria

Identification of freshwater microbiota and physicochemical analysis of water Waduk Lhok Batee Jeumpa

Biota components can provide an overview of the physical, chemical and biological conditions of a waters. One biota that can be used as a biological parameter in determining the condition of a waters is biota. Changes in the quality of water and its living substrate greatly affect the abundance and diversity of biota. The aim of this study was to identify fresh water microbiota and physicochemical analysis of water in the Lhok Batee Jeumpa Reservoir. The research method used is a combination of qualitative and quantitative research. Based on the research results, there are 13 types of Plankton consisting of 12 families in the Lhok Batee Reservoir. Plankton diversity is included in the low category with a diversity index of 0.4296. Dissolved Oxygen (DO) levels obtained the lowest value in sample 2-A of 4.70 mg/L and the highest value in samples 1-B, 4-B and 5-A of 5.20 mg/L, according to the standard quality Class 2 (4 mg/L). Biochemical Oxygen Demand (BOD) levels obtained the lowest value in sample 5-A of 1.00 mg/L and the highest value in sample 3-A of 12.50 mg/L, in accordance with Class 2 quality standards (3 mg/ L). Chemical Oxygen Demand (COD) levels obtained the lowest value in sample 1-B of 20.22 mg/L and the highest value in sample 5-B of 84.76 mg/L, according to Class 2 quality standards (25 mg/L).

Fish-mussel-algae-bacteria model remedied eutrophication pollution: Application in Dongxiang district reservoir

Eutrophication pollution has become an important ecological problem in China. Biological treatment is a common means to repair eutrophication pollution. Therefore, based on the biological manipulation technology, we put forward a fishing scheme for the Xiaoxiangshan and Shizishan reservoirs in Dongxiang District, which have been in a serious eutrophication pollution level for a long time, that is, to improve the quality and control water by operating fish, mussel, algae, and bacteria. The monitoring results in the middle stage of treatment showed that the structure of phytoplankton changed, and the degree of eutrophication pollution improved. In the later stage of treatment, the plankton diversity and richness of the two reservoirs increased significantly, the density and biomass of Cyanobacteria decreased significantly, and the degree of eutrophication pollution decreased to mesotrophic type. Overall, our research puts forward new ideas for the prevention and control of water eutrophication pollution and provides a reference for other kinds of water body treatment.

Temporal distribution of plankton and fish species at Mithamoin Haor: Abundance, composition, biomass and ecosystem based management approach

Wetlands are the major climatically vulnerable habitat globally. In Bangladesh, Haors are the representative of wetland habitat that plays a significant role in ecology, economy, and social structure. In the present study, physicochemical and biological properties and their interaction at Mithamoin haor of Kishoreganj district of Bangladesh were depicted based on the samples collected from July 2020 to June 202. In total, 46 genera representing 4 different groups of phytoplankton were identified comprising the highest percentages of Chlorophyceae (44.52 %). Zooplankton was represented with 13 genera which was dominated by rotifer. During the study, 56 fish species of 7 orders were documented and the dominance was showed by Cypriniformes (46.84 %). Fish biomass was highest during January and the lowest during May. Planktivores were represented the predominant (55.32 %) group in the haor. Water temperature, transparency, pH and water depth were considered as the major environmental factors influencing the phytoplankton, zooplankton and fish biomass of the haor. Although some fish and plankton species have declined over time, the overall diversity of fish and plankton in the Mithamoin haor was relatively stable. Multiple strategies, including an ecologically oriented framework, might be useful for conserving the prevailing fishery resources of this wetland in future.

KEANEKARAGAMAN PLANKTON DAN HUBUNGANNYA DENGAN KUALITAS AIR SUNGAI SEKITAR PABRIK KELAPA SAWIT (STUDI KASUS DI ASAM-ASAM, JORONG KABUPATEN TANAH LAUT)

The Asam-Asam River is one of the waters located in Tanah Laut Regency and is in an oil palm plantation area which is very close to the Palm Oil Mill (PKS). The Asam-Asam River has an important role for the surrounding community who use these waters as a source of water for the community around fishing activities, domestic activities such as washing clothes and supplying water for oil palm plantations. Water from PKS activities is thought to have changed the condition of the waters of the Asam-Asam river, therefore identification of plankton diversity in the Asam-Asam River was carried out and data collection of water quality parameters (pH, temperature, DO, BOD, COD, Nitrate and Phosphate) as supporting data for the identification results plankton. This research was conducted in August 2021. Observation points and water sampling were carried out at 2 stations in the Asam-Asam River. The supporting parameters observed were pH, temperature, DO, BOD, COD, nitrate and phosphate. Station II had the highest abundance of phytoplankton because the presence of the genera Oscillatoria, Tablelaria and Spirogyra was much higher than Station I. In the results of the two observation stations, the class Bacillariophyceae was the most common.

Effects of environmental factors on vertical distribution of the eukaryotic plankton community in early summer in Danjiangkou Reservoir, China

IntroductionEukaryotic plankton plays crucial roles in ecosystem processes, impacting aquatic ecosystem stability. This study focuses on Danjiangkou Reservoir, a canyon lake in central China, that acts as the water source of the Mid-route of the South-to-North Water Diversion Project.MethodsIn this study, high-throughput 18S rDNA gene sequencing was employed to investigate eukaryotic plankton community at four water depths (0.5 m, 5 m, 10 m, and 20 m). The environmental factors including pH, water temperature (WT), nitrate nitrogen (NO3−-N), ammonia nitrogen (NH4+-N), total nitrogen (TN), conductivity (Cond), and dissolved oxygen (DO) in reservoir areas were measured, and their correlations with abundance and diversity of eukaryotic plankton were analyzed.ResultsThe results showed the presence of 122 genera of eukaryotic plankton from 38 phyla. Eukaryotic plankton communities were mainly composed of Eurytemora, Thermocyclops, Sinocalanus, Mesocyclops, and Cryptomonas. In particular, significant differences in the diversity of eukaryotic plankton communities were found in vertical distribution. The diversity and abundance of eukaryotic plankton communities in 7 sampling sites decreased with the increase of depth from 0.5 to 10 m, while the diversity and abundance of plankton communities increased at 20 m. RDA analysis indicated that pH, depth, WT, NH4+-N, DO, Cond, and NO3−-N could influence the vertical distribution of the eukaryotic plankton community in the Danjiangkou Reservoir. Among these eukaryotic plankton, Eurytemora, Thermocyclops, and Volvox were negatively correlated with pH and WT and positively correlated with depth.DiscussionThis study revealed a novel perspective on the distribution of the eukaryotic plankton community in Danjiangkou Reservoir, particularly in terms of vertical variation, which will be helpful to comprehensively understand ecological processes and to further ensure the water quality safety in this canyon-style reservoir.

Plankton assemblages from microplastics of tropical coastal environments reveal high diversity and evidence of toxic species

Microplastics are a major constituent of plastic waste and are of an increasing global concern. Although microplastics are prevalent in marine ecosystems, the characterisation of plankton communities has been largely neglected in this aspect, especially in tropical ecosystems. To better understand the role of microplastics as a carrier of harmful plankton in marine ecosystems, epiplastic plankton communities in tropical marine ecosystems were studied from beach sediments along the Johor and Singapore Straits. Complementary analysis of microscopy and high throughput sequencing of the 16S rRNA (V3–V4) and 18S (V4) rRNA regions provided evidence that the plastisphere provided an appropriate environment to host a wide range of planktonic organisms. An average of 781 OTUs were identified across the three sampling sites. The structures of plankton communities were distinct across the sampling sites and were generally dominated by dinoflagellates, fungi and chlorophytes. We demonstrate that marine microplastics serve as microhabitats that are a host to harmful phytoplankton species, including viable resting cysts of dinoflagellates. Furthermore, plastics isolated from the location with the greatest anthropogenic influence demonstrated the greatest plankton diversity. This study presents evidence of diverse toxic plankton species present on the plastisphere and highlights its importance as a vector of the transport of harmful opportunistic species in relation to anthropogenic influence, in the marine environment.

The assessment of Plankton diversity in Yamuna River at selected sites in Haryana: A post-COVID-19 Study

The study was conducted in three sampling sites: Yamunanagar, Panipat, and Faridabad, along the Yamuna River. The samples were collected monthly from selected sampling sites from September 2021 to April 2022. Depending on their nature, plankton can be separated into two major groups, phytoplankton and Zooplankton. The qualitative analysis of these four samples in one site revealed that there are 17 genera of phytoplankton in total, belonging to four major groups, (i) Bacillariophyceae (consisting of 3 genera), (ii) Chlorophyceae (consisting of 10 genera), (iii) Euglenophyceae (consisting two genera), (iv) Cyanophyceae ( consisting three genera). A total of 30 genera of Zooplankton belong to four classes i) Protozoa, ii) Copepoda, iii) Cladocera and iv) Rotifers. Copepoda included ten genera, Cladocera included 13 genera, Rotifers included 05 genera, and Protozoa represented by two genera only. The diversity of phytoplankton was maximum in a segment first Yamunanagar (value of Simpson’s index is lower than 0.3416). The diversity of Zooplankton was maximum in segment first and almost equal to segment second Panipat. The temperature of river water ranged from 8.38±0.08 –21.33±0.13 °C, pH range from 6.00±0.11 - 8.03±0.11, D.O. from 1.68±0.06 – 8.10±0.007mg/l, total alkalinity from 83.25±0.48 – 351.75±11.89mg/l and total hardness 121.75±1.93 – 279.25±6.29mg/l.

Physicochemical parameters and plankton diversity from Lower River Benue, Makurdi

This study was conducted to investigate the abundance and diversity of plankton as well as the physicochemical properties of the Lower Benue River. The survey was carried out at different sites along the river both at Wadata and BSU Water Board. Samples were collected using plankton net into bottles preserved in 5% formalin and then transported to the laboratory for identification, counting and further analysis. A total of 39 plankton were observed out of which 28 (71.79%) were obtained at Wadata and 11 (28.21%) at BSU Water Board. The most abundant of all the species was Arthrospira plantensis which was observed 16 times. The least occurring plankton was the Paramecium species which was observed only once. The species richness at the Wadata location was 7 with a Shannon-Weinner Diversity Index of 1.383 and Evenness of 0.711. The species richness at the BSU Water Board on the other hand was 3 species with the Shannon-Weinner Diversity Index (H) of 0.935 and an Evenness of 0.851. A significant relationship between plankton abundance and sampling location was overserved (χ2 = 19.360; df = 1; p = 0.000). The Physicochemical properties of the Lower Benue River at the respective sampling locations revealed that air, water temperature and dissolved oxygen, had no significant difference observed between them (p>0.05). While pH of the water, electrical conductivity, turbidity and total dissolved solid had significant differences observed between them (p>0.05). A fairly strong non-significant positive relationship was observed between plankton abundance and the pH (r = 0.502; p = 0.389). Electrical conductivity (r = 0.629; p = 0.069) and total dissolved solid (r = 0.461; p = 0.298). On the other hand, a very strong non-significant negative relationship between plankton abundance and air temperature was observed (r = 0.819; p = 0.090). The relationship with turbidity was also negative and strong but they were significantly associated (r = 0.720; p = 0.029). Pearson’s correlation coefficient (r) further revealed a very weak non-significant relationship between plankton abundance and dissolved oxygen (r = 0.137; p = 0.747), while it showed no significant relationship with temperature (r = 0.047; p = 0.904).

Physicochemical parameters and plankton diversity in water from selected ponds within Makurdi Metropolis

Physicochemical parameters and plankton diversity in water from five (5) selected ponds was investigated. In the investigation, some physicochemical parameters of water, the composition and abundance of plankton were determined. Some of the parameters include temperature, electrical conductivity, pH, dissolved oxygen, nitrates and phosphate. The samples were collected and transported to the laboratory of the Department of Fisheries and Aquaculture, Joseph Sarwuan Tarka University Makurdi for analysis. The preserved plankton samples were observed using a digital Celestron compound microscope and digital Celestron cosmos dissecting microscope. A combination of keys and guides provided were used for identification of the plankton species. A total of 13 different plankton species, with a total abundance of 308 were observed. The most abundant species was Chlorella vulgaris with an abundance of 85 and was observed in all three pond types. This was followed by Scenedesmus acutus (45) which was observed only in the concrete and liner ponds. Paramecium was next and was observed only in the earthen and concrete ponds. The rest of the plankton species were observed in only one pond type. The physicochemical parameters for the selected earthen, concrete and liner ponds were also selected. The pH and dissolved oxygen were observed to be higher in the concrete pond and lowering the liner pond. The electrical conductivity and total dissolved solid were however lower in the concrete pond and higher in the earthen pond, both the temperature and turbidity were higher in the liner pond and lower in the earthen pond. The phosphate concentration was also higher in the linear pond and lower in the earthen pond, while the concentration of Nitrite was equal in both earthen and concrete pond with no amount observed in the liner pond.

Study of the development of milkfish (Chanos-chanos sp.) cultivation based on plankton aspects

Background: Mandalle Beach, Pangkep Regency, is located in a coastal area with areas consisting of beaches, river estuaries, mangrove forests, rice fields, ponds, and residential areas. This area has potential for fish cultivation, especially milkfish cultivation. To support data and information about the prospects for cultivating milkfish in this region, a study was carried out on biological aspects, especially plankton. Materials and Methods: The research was carried out at five research locations, namely: location 1 is on the coast, which borders the coast of Barru Regency; location 2 is the location around the Pangkep State Agricultural Polytechnic Campus Pier; location 3 is on the beach, where mangrove vegetation grows around it; location 4, namely at the mouth of the river, which borders Mandalle Village and Tamarupa Village; and location 5, namely in the part adjacent to the rice fields and ponds of Mandalle Village. The plankton parameters tested were plankton abundance, variety, and dominance. The data obtained was then processed and analyzed using descriptive analysis. The plankton parameters tested were abundance, uniformity, diversity, and plankton dominance. The data obtained was then processed and analyzed using descriptive analysis. Results: The results showed that plankton abundance (cells/ml) was in the range of 250–300 cells/ml. Each research location has different types of plankton, which have the highest abundance. The plankton uniformity index value is in the range of 0.18108–0.22653, with the highest uniformity value occurring at location 2 and the lowest at location 3. The types of plankton that dominate in each research location are Chaetoceros sp., Gyrodinium sp., Thallasionema sp., Gymnodinium, and Cosconodiscus, but the most dominant type of plankton in all research locations is Chaetoceros sp., namely 0.461538462. Conclusions: Based on the study of the type, abundance, diversity, uniformity, and dominance of plankton, it can be stated that, based on the plankton aspect, the waters of Mandalle Beach, Pangkep Regency, are suitable and meet the requirements for cultivating milkfish; however, due to the large number of fishing activities and the proximity of residential areas and rice fields, the cultivation technique What is recommended is traditional or semi-intensive milkfish cultivation.

Community assembly and network stability of picoeukaryotic plankton communities in the northeast Indian Ocean

Picoeukaryotic plankton played as key components of marine microbial communities, and participate in the marine food webs, especially the carbon cycling. Despite their importance, little is known about the mechanisms of assembly and network stability of picoeukaryotic plankton in the ocean along vertical gradients. Here, we obtained new dataset on the dynamics of picoeukaryotic plankton communities in the northeast Indian Ocean with a vertical gradient of 0–2000 m on two cruises. The diversity of picoeukaryotic plankton gradually decreased along the vertical gradient, with photosynthetic plankton mainly distributed in the epipelagic zone and heterotrophs dominating in the mesopelagic zone. Temperature and dissolved oxygen were the main environmental factors affecting the structure of the picoeukaryotic plankton community along the vertical gradient. The community assembly mechanisms also differed among different water layers, with the epipelagic zone dominated by stochastic processes and the mesopelagic zone controlled by deterministic processes, and heterogeneous selection processes were the main drivers shaping the picoeukaryotic plankton community structure. In addition, picoeukaryotic plankton community network stability showed nonlinear changes in vertical gradients, the mesopelagic zone is dominated by deterministic processes and therefore most resistant to environmental disturbances. Our results provide new insights into the plankton ecology of the northeast Indian Ocean and the structure of microbial communities and networks along vertical gradients.

Habitat and food habits of the endemic fish Oryzias eversi in Tana Toraja, South Sulawesi, Indonesia

Abstract. Lamba T, Ambeng, Andriani I. 2023. Habitat and food habits of the endemic fish Oryzias eversi in Tana Toraja, South Sulawesi, Indonesia. Biodiversitas 24: 5137-5145. The population of the medaka fish species, Oryzias eversi, was categorized as Near Threatened by the International Union for Conservation of Nature (IUCN) 2019 due to its restricted distribution and occurrence in a single threatened location. One way to protect this species from extinction is through captive breeding, which requires understanding its habitat conditions and food habits. Therefore, this research aimed to analyze the habitat conditions and food habits of Oryzias eversi (Hadiaty & Nolte, 2012) in Tilanga Pool, Tana Toraja. Purposive random sampling was used to obtain fish samples, while habitat conditions were determined by measuring environmental parameters, and the abundance and diversity of plankton. Food habits were analyzed by calculating the Index of Preponderance (IP) and Relative Gut Length (RGL). The results indicated that O. eversi inhabited a highly polluted habitat with dissolved oxygen content that ranged from 3.95 to 4.16 mg/L. The abundance of phytoplankton and zooplankton ranged from 185-435 cells/L and 10-25 ind/L, respectively. Phytoplankton diversity was in the moderate category, while zooplankton was low, with average values of Diversity Index (H’) ranging from 1.61-1.93 and 0.69-024, respectively. IP and RGL showed that O. eversi was an omnivore-carnivore fish. The average IP of zooplankton and phytoplankton ranged from 0.35-61.11% and 0.69-1.04%, respectively. Meanwhile, the RGL ranged from 0.48 to 0.62, respectively. Cyclops sp. larvae were identified as the primary food source for O. eversi with IP above 40% and Eurycercus sp. with IP range of 4-40% as additional food.

Evaluating the quality of aquatic environment on the Planktonic-Index of Biotic Integrity (P-IBI) based whiteleg shrimp Litopenaeus vannamei (Boone, 1931) ponds

Abstract. Akbarurrasyid M, Prajayati VTF, Sofian A, Katresna M. 2023. Evaluating the quality of aquatic environment on the Planktonic-Index of Biotic Integrity (P-IBI) based whiteleg shrimp Litopenaeus vannamei (Boone, 1931) ponds. Biodiversitas 24: 4845-4853. Plankton is one of the biotic indicators used to evaluate the quality of the aquatic environment in the ponds. This study aims to find out the quality of the aquatic environment of the whiteleg shrimp Litopenaeus vannamei (Boone, 1931) ponds using Planktonic-Index Biotic of Integrity (P-IBI). Samples were collected in intensive L. vannamei farming in Pandeglang, Banten, and analyzed by the P-IBI method using 4 categories and 35 attributes. Matrix attributes include community composition, number of species, species density and species diversity. The P-IBI value is compared with the assessment category to obtain the status of aquatic environmental quality. The environmental quality assessment categories are: very good (83-100%), good (73-82%), moderate (57-72%) and bad (0-56%). The results of the study showed the assessment of Community Composition (CC) of 66 (66%) and the scoring of Amount of Species (AS) of 65 (59.09%) on the attributes of the number of Bacilloryophycea, percentage of Cyanophycea, Dinophyceae, and Protozoa. The scoring of Species Density (SD) obtained 65 (59.09%) on attributes of the abundance of Chlorophyceae and Bacilloryophycea and the low abundance of Dinophyceae and Protozoa. Meanwhile, the scoring of Species Diversity (SDI) obtained a maximal score of 30 (100%), which showed that the species diversity of plankton based on the Shannon-Wiener Index (H'), Margalef Index (E), and Pielou Index (D) was still in good condition, the species diversity was stable, and there were no dominating species. The P-IBI score obtained was in the moderate category for L. vannamei farming activities.

Microfacies Analysis of Mixed Siliciclastic-Carbonate Deposits in the Early-Middle Ordovician Meitan Formation in the Upper Yangtze Platform in SW China: Implications for Sea-Level Changes during the GOBE

During the Early-Middle Ordovician, the Upper Yangtze Platform experienced extensive development of a distinctive set of mixed siliciclastic-carbonate deposits known as the Meitan Formation. To conduct a comprehensive study of the relationship between mixed sedimentation and sea-level changes, the Hailong section, situated at the southwest margin of the Upper Yangtze Platform in SW China, was selected as the study area due to its typical mixed sedimentary sequence. This section was effectively compared with sections in other regions. Clustering analysis of the point-count groups from the Honghuayuan and Meitan Formations revealed nine microfacies that developed during this period. Such a diverse range of microfacies provides the evidence of frequent sea-level changes in the Yangtze Platform throughout this period. Specifically, two sea-level rises were identified during the early TS.2b and early TS.3b, with the early TS.2b event occurring globally. Furthermore, four sea-level falls were observed in the late TS.2b, TS.2c, TS.3a, and late TS.3b periods. The late TS.2b sea-level fall was globally significant. From TS.2c onwards, distinct variations in sea-level changes among the Yangtze Platform, North China, Baltoscandia, Australia, and North America emerged due to alterations in the paleogeographic pattern. By comparing the sea-level curves in the Upper Yangtze Platform with the diversity curves of chitinozoans, acritarchs, and brachiopods, it became evident that environmental changes played a crucial role in the Great Ordovician Biodiversification Event (GOBE), especially during the Floian. The rising sea level and increased detrital materials fostered the development of diverse habitats, prompting organisms to adapt to varying environments. In general, rising sea levels favored increased brachiopod diversity, while falling sea levels favored enhanced planktonic diversity among chitinous and acritarch species. By shedding new light on the relationship between Ordovician sea-level changes and biodiversification in the Yangtze region, this study offers a fresh perspective on the subject from the microfacies analysis.

Radiodont frontal appendages from the Fezouata Biota (Morocco) reveal high diversity and ecological adaptations to suspension-feeding during the Early Ordovician

IntroductionThe Early Ordovician Fezouata Shale Formation (485–475Ma, Morocco) is a critical source of evidence for the unfolding Great Ordovician Biodiversification Event (GOBE), the largest radiation in animal diversity during the Paleozoic. The Fezouata Shale preserves abundant remains of ancient marine organisms, including hundreds of specimens of radiodonts, a diverse and globally distributed group of stem lineage arthropods that first appeared as raptorial predators during the Cambrian Explosion.MethodsIn this work, we study 121 radiodont frontal appendages from the Fezouata Shale. Frontal appendages are the most commonly preserved body parts of radiodonts, and their well-preserved anatomical characters are crucial for describing taxonomic diversity at the species level, while also providing essential data on mode of life, paleoecology, and feeding behaviour.ResultsOur data allow for a systematic review of suspension-feeding Hurdiidae radiodonts from Fezouata. The genus Pseudoangustidontus is recognised as a radiodont and ascribed to Hurdiidae, and a new second species of this genus is identified, Pseudoangustidontus izdigua sp. nov. Aegirocassis benmoulai is also reviewed and its diagnosis amended with new details of differentiated endites in this appendage. The morphological similarity between both genera allows us to erect Aegirocassisinae subfam. nov., which groups together the suspension-feeding hurdiids of the Fezouata Shale.DiscussionSuspension-feeding radiodont appendages are more abundant than those of sediment sifting or raptorial radiodonts, with the Fezouata Shale showing the highest diversity of suspension-feeding radiodonts in the history of the group. This dominance and diversity of frontal filter-feeding appendages follows the “Ordovician Plankton Revolution”, which started in the upper Cambrian and saw a huge radiation in plankton diversity.

Phytoplankton diversity explained by connectivity across a mesoscale frontal system in the open ocean

Phytoplankton community composition is important in establishing ecosystem structure and function. Intuitively, we recognize that water movements must be important for modifying spatial gradients and plankton diversity. However, identifying boundaries and exchange between habitats in the open ocean is not straightforward. Here, we use the abundance of nine phytoplankton species closely sampled in a mesoscale frontal system in the northeastern North Sea as a proxy for community composition and explore the relationship between phytoplankton biogeography and transport patterns. Subsurface community distributions could be related to modeled patterns in water movement. A methodology for analyzing pelagic diversity that includes a representation of plankton community composition and an Eulerian connectivity tracer was developed, and the relative importance of connectivity and geographical distance for phytoplankton species composition analyzed. The connectivity tracer identifies timescales and dispersal barriers in the open ocean. Connectivity was found to be superior in explaining pelagic plankton diversity and found to be a prerequisite for understanding the pelagic phytoplankton composition. This approach is a valuable tool for establishing the link between ocean transports, ecosystem structure and biodiversity and for informing the placement of marine protected areas.

Environmental DNA reveals spatial patterns of fish and plankton diversity at a floating offshore wind farm

AbstractIn this study, we collected water eDNA from sampling stations at the first full scale floating offshore wind farm (OWF), the Hywind Pilot Park, east of Peterhead, UK, and a nearby reference area. We combined targeted droplet digital PCR (ddPCR) quantification of two commercially important species, Atlantic mackerel (Scombrus scombrus) and Atlantic herring (Clupea harengus), with metabarcoding of fish and plankton communities. The goal of this study was to assess the performance of eDNA data to characterize pelagic communities and its use for environmental monitoring. The metabarcoding recovered 26 fish species including both pelagic and demersal taxa. The plankton data were dominated by dinoflagellates (Karenia) and calanoid copepods. We found that both specific quantification of eDNA from mackerel and herring and eDNA metabarcoding of fish communities were able to reveal spatial patterns: Mackerel was most abundant in the surface across both OWF and reference sites; herring was present at a wider depth range. While ddPCR and metabarcoding data for these two species were broadly congruent, we observed detection/non‐detection mismatches for both methods, highlighting the need for robust sampling design. There was no consistent OWF versus reference area pattern in the demersal fraction of fish assemblages. We interpret our findings as representing a snapshot of fish school location around the time of sampling, and do not consider the single timepoint data from this pilot study to be sufficient to attribute any effects to the OWF itself. As a non‐invasive tool, we conclude that eDNA has a high potential in future environmental monitoring of OWFs. We recommend further ground‐truthing and biomass correlation of eDNA data with catch data and establishing eDNA time series as next steps towards implementation of eDNA in OWF environmental monitoring.