Ocean Colour remote sensing in the Southern Laptev Sea: evaluation and applications

Enhanced permafrost warming and increased arctic river discharges have heightened concern about the input of terrigeneous matter into Arctic coastal waters. We used optical operational satellite data from the Ocean Colour sensor MERIS onboard the ENVISAT satellite mission for synoptic monitoring of the pathways of terrigeneous matter in the southern Laptev Sea. MERIS satellite data from 2006 on to 2011 were processed using the Case2Regional Processor, C2R, installed in the open-source software ESA BEAM-VISAT. Since optical remote sensing using Ocean Colour satellite data has seen little application in Siberian Arctic coastal and shelf waters, we assess the applicability of the calculated MERIS parameters with surface water sampling data from the Russian-German ship expeditions LENA2010 and TRANSDRIFT-XVII taking place in August and September 2010 in the southern Laptev Sea. The surface waters of the southern Laptev Sea are characterized by low transparencies, due to turbid river water input, terrestrial input by coastal erosion, resuspension events and, therefore, high background concentrations of Suspended Particulate Matter, SPM, and coloured Dissolved Organic Matter, cDOM. The mapped calculated optical water parameters, such as the first attenuation depth, Z90, the attenuation coefficient, k, and Suspended Particulate Matter, SPM, visualize resuspension events that occur in shallow coastal and shelf waters indicating vertical mixing events. The mapped optical water parameters also visualize that the hydrography of the Laptev Sea is dominated by frontal meanders with amplitudes up to 30 km and eddies and filaments with diameters up to 100 km that prevail throughout the ice-free season. The meander crests, filaments and eddy-like structures that become visible through the mapped MERIS C2R parameters indicate enhanced vertical and horizontal transport energy for the transport of terrigenous and living biological matter in the surface waters during the ice-free season

FROM FRESH- TO MARINE WATERS: THE FATE OF DISSOLVED ORGANIC MATTER IN THE LENA DELTA REGION, SIBERIA

The connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change. This is influencing both freshwater budgets and the supply of carbon to sea. This study characterizes the composition of dissolved organic matter (DOM) within the Lena Delta region across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis, with a clear dominance of humic-like signals in fresh waters. At higher salinities there was an increased autochthonous contribution. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and, as a response to the hydrographical forcing, the region displayed a pseudo-conservative behavior of DOM in relation to salinity at marine-influenced sites; and a non-conservative behavior with evidence of considerable removal of DOM (up to 54%), likely driven by photodegradation and sorption/flocculation, at sites influenced by the Lena River plume. The latter mixing curve was split into three mixing regimes with regard to different amount and reactivity degree of DOM and to the factors driving DOM variability: 1) the low salinity regime (salinity>10) with high concentrations of DOM, dominated by highly reactive terrigenous contribution and characterized by rapid removal; 2) the intermediate regime (1025) showing the lowest DOM and an increased contribution of less reactive compounds, displaying a pseudo-conservative behavior, with relatively low removal/addition processes controlling the dilution of DOM

Global impacts of the 1980s regime shift

Despite evidence from a number of Earth systems that abrupt temporal changes known as regime shifts are important, their nature, scale and mechanisms remain poorly documented and understood. Applying principal component analysis, change-point analysis and a sequential t-test analysis of regime shifts to 72 time series, we confirm that the 1980s regime shift represented a major change in the Earth's biophysical systems from the upper atmosphere to the depths of the ocean and from the Arctic to the Antarctic, and occurred at slightly different times around the world. Using historical climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and statistical modelling of historical temperatures, we then demonstrate that this event was triggered by rapid global warming from anthropogenic plus natural forcing, the latter associated with the recovery from the El Chichón volcanic eruption. The shift in temperature that occurred at this time is hypothesized as the main forcing for a cascade of abrupt environmental changes. Within the context of the last century or more, the 1980s event was unique in terms of its global scope and scale; our observed consequences imply that if unavoidable natural events such as major volcanic eruptions interact with anthropogenic warming unforeseen multiplier effects may occur

Alien Planktonic Species in the Marine Realm: What Do They Mean for Ecosystem Services Provision?

Human well-being is significantly affected by the contributions provided by ecosystems, or ecosystem services. In this well-illustrated atlas, world-class experts identify and discuss key driving forces, trade-offs, and synergies of ecosystem services. Through interdisciplinary case studies varying across ecosystems and scales, this atlas narrows the knowledge gap between ecosystem services management and related fields of study. This atlas begins with conceptual background and proceeds to present drivers and their risks for ecosystems, their functions and services, and biodiversity. Trade-offs and synergies among ecosystem services and societal responses to the drivers and trade-offs are discussed. Sustainable land management and governance concepts are demonstrated throughout the atlas. Environmental scientists, practitioners and policy makers worldwide will appreciate the solutions and best practices identified throughout the chapters. Students of environmental sciences, socio-economics and landscape planning will find this atlas to be a valuable read, as well

Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique “pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new bylaws as the Manila clam is spreading to other protected estuaries in the region

3 year report on activities for the Working Group on Phytoplankton and Microbial Ecology (WGPME)

The ICES Working Group on Phytoplankton and Microbial Ecology (WGPME) provides tools and expert perspectives on the sampling methods, ecology and diversity of phytoplankton and other planktonic microbes. The group set out terms of reference to improve access to data, crossdisciplinary approaches and to develop ecological interpretations of the changing phytoplankton seascape. The group published 16 papers between 2019–2021, including key tools, high-profile synthesis papers and science reports. Tools: The group has progressed efforts to collect images of commonly used Lugol’s-preserved phytoplankton, alongside live images to aid those in correctly identifying species. Members have noticed and published records of new phytoplankton species. The group aims to produce a New Records database to assist in notifying new or reoccurrence of a species. WGPME work, with other Expert Groups (EG) to improve access to molecular genetic tools and records. A multi-EG thematic session has been submitted for ICES ASC 2022 in cooperation with other EGs, whilst phytoplankton barcoding information will be incorporated into the Working Group on Integrated Morphological and Molecular Taxonomy (WGIMT) barcoding Atlas (https://metazoogene.org/atlas). Information and access: The group is gathering information on nano and picoplankton (small phytoplankton less than 10 and 2µm respectively) to incorporate into global datasets such as GLOMICON. Multiple data sources point to an increasing trend in picoplankton and few indicators exist in current EU or national legislation to measure their impact on marine ecology. Many members are involved in indicator development for governmental and pan-governmental organisations such as OSPAR. However, the number and level of indicators vary in each country. Long-term ecology: The cooperative zooplankton and phytoplankton report has been delayed but initial analysis has indicated ≥30 years of data reliably shows spatio-temporal trends in phytoplankton and the effects of temperature on key phytoplankton groups. Two research papers are being produced on climate change effects on key marine phytoplankton species with the additional aim of improving indicators of change using species-specific information

Molecular analyses of protists in long-term observation programmes—current status and future perspectives

Protists (microbial eukaryotes) are diverse, major components of marine ecosystems, and are fundamental to ecosystem services. In the last 10 years, molecular studies have highlighted substantial novel diversity in marine systems including sequences with no taxonomic context. At the same time, many known protists remain without a DNA identity. Since the majority of pelagic protists are too small to identify by light microscopy, most are neither comprehensively or regularly taken into account, particularly in Long-term Ecological Research Sites. This potentially undermines the quality of research and the accuracy of predictions about biological species shifts in a changing environment. The ICES Working Group for Phytoplankton and Microbial Ecology conducted a questionnaire survey in 2013–2014 on methods and identification of protists using molecular methods plus a literature review of protist molecular diversity studies. The results revealed an increased use of high-throughput sequencing methods and a recognition that sequence data enhance the overall datasets on protist species composition. However, we found only a few long-term molecular studies and noticed a lack of integration between microscopic and molecular methods. Here, we discuss and put forward recommendations to improve and make molecular methods more accessible to Long-term Ecological Research Site investigators

Phylogeny and cultivation of the holocarpic oomycete Diatomophthora perforams comb. nov., an endoparasitoid of marine diatoms

Oomycetes infecting diatoms are biotrophic parasitoids and live in both marine and freshwater environments. They are ubiquitous, but the taxonomic affinity of many species remains unclear and the majority of them have not been studied for their molecular phylogeny. Only recently, the phylogenetic and taxonomic placement of some diatom-infecting, early-diverging oomycetes was resolved, including the genera Ectrogella, Miracula, Olpidiopsis, and Pontisma. A group of holocarpic diatom parasitoids with zoospores swarming within the sporangium before release were found to be unrelated to the known genera with diatom-infecting species, and were re-classified to a new genus, Diatomophthora. However, about a dozen species of holocarpic diatom parasitoids with unclear affinity remained unsequenced, which includes a commonly occurring species so far identified as Ectrogella perforans. However, this assignment to Ectrogella is doubtful, as the species was not reported to feature a clear-cut diplanetism, a hallmark of Ectrogella s. str. and the whole class Saprolegniomycetes. It was the aim of the current study to clarify the phylogenetic affinities of the species and if the rather broad host range reported is correct or a reflection of cryptic species. By targeted screening, the parasitoid was rediscovered from Helgoland Roads, North Sea and Oslo Fjord, Southern Norway and investigated for its phylogenetic placement using small ribosomal subunit (18S) sequences. Stages of its life cycle on different marine diatoms were described and its phylogenetic placement in the genus Diatomophthora revealed. A stable host-parasite axenic culture from single spore strains of the parasitoid were established on several strains of Pleurosigma intermedium and Coscinodiscus concinnus. These have been continuously cultivated along with their hosts for more than 2 years, and cultural characteristics are reported. Cross-infection trials revealed the transferability of the strains between hosts under laboratory conditions, despite some genetic distance between the pathogen strains. Thus, we hypothesise that D. perforans might be in the process of active radiation to new host species

From fresh to marine waters: characterization and fate of dissolved organic matter in the Lena River Delta region, Siberia

Connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change, influencing both freshwater budgets, and the supply of carbon to the sea. This study characterizes the optical properties of dissolved organic matter (DOM) within the Lena Delta region and evaluates the behavior of DOM across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis (PARAFAC) with a clear dominance of allochthonous humic-like signals. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and had their distribution coupled with hydrographical conditions. Higher DOM concentration and degree of humification were associated with the low salinity waters of the Lena River. Values decreased toward the higher salinity Laptev Sea shelf waters. Results demonstrate different responses of DOM mixing in relation to the vertical structure of the water column, as reflecting the hydrographical dynamics in the region. Two mixing curves for DOM were apparent. In surface waters above the pycnocline there was a sharper decrease in DOM concentration in relation to salinity indicating removal. In the bottom water layer the DOM decrease within salinity was less. We propose there is a removal of DOM occurring primarily at the surface layer, which is likely driven by photodegradation and flocculation