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Storm events alter marine snow fluxes in stratified marine environments
Get PDFMarine snow is an important part of the biological pump and marine food web, and although previous research has provided a thorough understanding of the underlying mechanisms of marine snow dynamics in general, there is still a knowledge gap concerning extreme conditions, such as storm events. Storms are predicted to increase in magnitude and frequency in the future, and could potentially have a large impact on marine snow dynamics. For these reasons, we assessed the effects of storm events on marine snow dynamics in the Baltic Sea, an area chosen due to its well-studied and stable stratified conditions outside of meteorologically extreme events. The combination of in-situ imaging and biogeochemical environmental data from three different years facilitates an assessment of storm event impacts, while simultaneously excluding the possibility that patterns in particle distribution and abundances were due to other environmental influences. The results show that extreme meteorological events such as storms can increase the abundance of marine snow in stratified marine environments by a factor of 10 or more. The particles are distributed more widely and are larger, brighter, rounder and less complexly shaped. In non-extreme conditions, particles have been observed to deposit along the density gradients in thin-layer aggregations. This study indicates that storms can episodically disrupt these formations, thereby altering vertical flux and export potentials across stratification boundaries. In addition, we observed that marine snow abundances are drastically higher in the aftermath of storm events than under calm conditions, potentially due to the disaggregation of larger particles and lateral import of resuspended matter from shallower areas. In light of the increased frequency and magnitude of storms in the future due to climate change, our findings indicate that marine snow dynamics in stratified environments might be altered permanently
The silent majority: Pico- and nanoplankton as ecosystem health indicators for marine policy
Get PDFA healthy marine ecosystem is a fully functioning system, able to supply ecosystem services whilst still maintaining resilience to human-induced environmental change. Monitoring and managing the health of resilient marine ecosystems requires indicators that can assess their biodiversity state and food web functioning. Plankton are crucial components of pelagic habitats, occupying the base of the pelagic food web. Larger plankton have long been used to monitor ecosystem productivity and biodiversity due to their identification via traditional light microscopy. In contrast, the regular monitoring of pico- and nanoplankton (<20 µm; hereafter called “tiny plankton”) only started with the development of flow cytometry techniques, which has limited their inclusion as ecosystem health indicators. Four UK plankton surveys have sampled and identified these tiny plankton for up to 14 years, providing an
opportunity to test their suitability as indicators of ecosystem state. We investigated six groups of tiny plankton,
including heterotrophic nanoeukaryotes, photosynthetic nanoeukaryotes, photosynthetic picoeukaryotes, and
Synechococcus cyanobacteria, and two groups of heterotrophic bacteria. Flow cytometry and light microscopy data from an inshore Western English Channel station revealed that 99.98 % of plankton abundance and 71 % of plankton biomass was derived from tiny plankton cells too small to be quantified accurately under a light mi�croscope and thus not adequately considered in assessments of pelagic habitats. Different UK marine and coastal regions showed consistency in peak abundances of these tiny plankton. We used a novel wavelet coherence method to identify time-based relationships between tiny plankton and envi�ronmental variables linked to human pressures. Relationships were found between nitrogenous nutrients and all
tiny plankton groups, most commonly at sub-annual to annual time scales. Photosynthetic picoeukaryotes, heterotrophic nanoeukaryotes, and HNA-bacteria were associated with high sea surface temperatures. Given the here established relationship between tiny plankton and environmental variables, and their importance in the full plankton assemblage, we recommend that, alongside existing microplankton lifeforms, tiny plankton groups can be used as plankton lifeforms, either individually or in combination, to inform biodiversity indicators that
meet policy obligations under the EU Marine Strategy Framework Directive (MSFD), (Oslo-Paris Convention) OSPAR strategies, and the UK Marine Strategy
Observing change in pelagic animals as sampling methods shift: the case of Antarctic krill
No full textUnderstanding and managing the response of marine ecosystems to human pressures including climate change requires reliable large-scale and multi-decadal information on the state of key populations. These populations include the pelagic animals that support ecosystem services including carbon export and fisheries. The use of research vessels to collect information using scientific nets and acoustics is being replaced with technologies such as autonomous moorings, gliders, and meta-genetics. Paradoxically, these newer methods sample pelagic populations at ever-smaller spatial scales, and ecological change might go undetected in the time needed to build up large-scale, long time series. These global-scale issues are epitomised by Antarctic krill (Euphausia superba), which is concentrated in rapidly warming areas, exports substantial quantities of carbon and supports an expanding fishery, but opinion is divided on how resilient their stocks are to climatic change. Based on a workshop of 137 krill experts we identify the challenges of observing climate change impacts with shifting sampling methods and suggest three tractable solutions. These are to: improve overlap and calibration of new with traditional methods; improve communication to harmonise, link and scale up the capacity of new but localised sampling programs; and expand opportunities from other research platforms and data sources, including the fishing industry. Contrasting evidence for both change and stability in krill stocks illustrates how the risks of false negative and false positive diagnoses of change are related to the temporal and spatial scale of sampling. Given the uncertainty about how krill are responding to rapid warming we recommend a shift towards a fishery management approach that prioritises monitoring of stock status and can adapt to variability and chang
Gathering users and developers to shape together the next-generation ocean reanalyses: Ocean reanalyses workshop of the European Copernicus Marine Service
Get PDF1. Objectives of the workshop
Ocean reanalyses are reconstructions of the past ocean state combining ocean numerical models and Earth observations through data assimilation techniques. As a result of their temporal and spatial consistency and continuity compared to Earth observations only and their high accuracy and quality compared to pure numerical model simulations, ocean reanalysis data are widely used in the scientific community (e.g., ocean and climate process studies) and private sectors (e.g., operational planning, shipping, and fisheries). For almost a decade, the Copernicus Marine Service has provided users with high-quality, regularly extended global and regional ocean reanalyses. The objective of this workshop was to gather the international community to 1) understand the users’ needs for ocean reanalyses, 2) identify the strengths and weaknesses of current ocean reanalyses, 3) establish the way forward toward the next generation of ocean reanalyses by improving different aspects of these products to meet users’ needs and science ambitions, and 4) improve collaborations within the community.
The 3-day workshop was held in Toulouse (France) and brought together ocean reanalysis users, producers from European Copernicus services and beyond, and scientific experts on different aspects (data assimilation, ocean models, and observations). The workshop’s hybrid format (online and in person) enabled us to welcome around 60 people in person and 1400 registrations online, with 700 unique connections on day 1, 350 on day 2, and 250 on day 3. The key findings of each objective are given in the following sections; the last section highlights the next steps the ocean reanalyses community will carry out
Nutrient Recycling and Waste Remediation as a Service From Estuarine and Coastal Ecosystems
Get PDFThe purpose of this chapter is to review environmental and ecological economics research on nutrient recycling and waste remediation of coastal ecosystems. For this purpose, two main questions are addressed: What are the monetary values associated with the ecosystem service of nutrient and waste remediation (NWR)? And, what characterizes good management of this service? It is found that values have mainly been assigned to nutrient treatment by coastal wetlands and shellfish although studies in other types of habitats e.g., kelp, seagrass and sediments are emerging. Removal of nutrients, revealed by a literature comparison of wetlands, ranged between €0–172,227 using a replacement cost valuation approach. It is also observed that nutrient neutrality policies have been implemented in practice for mitigating degradation of coastal ecosystems, but these differ in different parts of the world. The chapter also points at promising future mitigation options using marine nature based solutions, such as bivalve, kelp and seaweed farming
What time is the tide? The importance of tides for ocean colour applications to estuaries
Get PDFTides can play a major role in transitional water dynamics, being the primary driver of fluctuations in water parameters. In the last decade, remote sensing methods have become a popular tool for cost-effective systematic observations, at relatively high spatial and temporal scales. However, the presence of tides introduces complexities, given that Sun-synchronous satellites will observe a different tidal condition at each overpass, effectively aliasing the daily signal. This can create nonobvious biases when using remote sensing data for monitoring tidally-dominated systems, potentially leading to misinterpretation of patterns and incorrect estimates of periodicities. In this work, we used a six-year Sentinel-2-derived turbidity dataset to evaluate the impact of tidal
aliasing on the applicability of a Sun-synchronous satellite to a tidally-dominated system (Tagus estuary, Portugal). Each satellite observation was classified according to tidal phase. Results indicate that tidal processes dominated over seasonal variability, with significant differences
observed between turbidity levels of different tidal phases (p < 0.0001). Climatology analyses also revealed significant changes between all-data and per-tidal-phase data (p < 0.001), highlighting the importance of classifying satellite data by tidal condition. Additionally, tidal condition labelling at each Sentinel-2 overpass revealed that not all tidal conditions are observed by a Sun-synchronous satellite, as Low tide and Floods are always observed during Spring tides and High tide and Ebbs observed under Neap tides. Spring Low tides are overrepresented compared to all other tidal conditions. This result is particularly relevant for water quality monitoring based on remote sensing data in tidally-dominated systems
Exploring steric sea level variability in the Eastern Tropical Atlantic Ocean: a three-decade study (1993–2022)
Get PDFSea level rise (SLR) poses a signifcant threat to coastal regions worldwide, particularly afecting
over 60 million people living below 10 m above sea level along the African coast. This study analyzes
the spatio-temporal trends of sea level anomaly (SLA) and its components (thermosteric, halosteric
and ocean mass) in the Eastern Tropical Atlantic Ocean (ETAO) from 1993 to 2022. The SLA trend
for the ETAO, derived from satellite altimetry, is 3.52 ± 0.47 mm/year, similar to the global average
of 3.56 ± 0.67 mm/year. Of the three upwelling regions, the Gulf of Guinea (GoG) shows the highest
regional trend of 3.42 ± 0.12 mm/year. Using the ARMORD3D dataset, a positive thermosteric sea
level trend of 0.88 ± 0.04 mm/year is observed, particularly in the equatorial and southern Atlantic
regions. The steric component drives the interannual SLA variability, while the ocean mass component
dominates the long-term trends, as confrmed by the GRACE and GRACE-FO missions for 2002–2022.
For those two decades, the total SLR from altimetry amounts to 3.80 ± 0.8 mm/year, whilst the
steric component is reduced to only 0.19± 0.05 mm/year, leaving a residual increase in the ETAO of
3.69 ± 0.5 mm/year. The independent mass change from GRACE amounts to 2.78 ± 0.6 mm/year for
this region, which just closes the sea level budget within present uncertainty levels. Spatial analysis of
the steric components indicates a warming along the equatorial African coast including the GoG and
a freshening near Angola. Strong correlations with regional climate factors, particularly the Tropical
South Atlantic Index, highlight the infuence of persistent climate modes. These fndings underscore
the urgent need for mitigation and adaptation strategies to SLR in the ETAO, especially for densely
populated coastal communitie
NEW OPPORTUNITIES TO PROMOTE BLUE SCHOOLS: SCHOLAR GRANTS, EDUCATIONAL RESOURCES, AND CITIZEN SCIENCE UNDER THE PROBLEU PROJECT
No full textA Blue School integrates water themes into its curriculum, using project-based learning to involve students in marine, maritime, and freshwater subjects. This fosters awareness and a sense of stewardship for the ocean. These schools are clustered under the Network of European Blue Schools (NEBS) umbrella.
In this context, ProBleu, a European-Commission--funded project, faces the challenge of expanding and supporting the NEBS while promoting citizen science to mobilise and engage children, youth, teachers, and school communities across the European Union and associated countries. The initiative to expand and support the NEBS aligns well with the objectives of the EU Mission “Restore ocean and waters before 2030” and broader environmental education goals. By enhancing ocean and water literacy among school communities, this initiative contributes to restoring the oceans and waters by 2030.
ProBleu offers several tools to teachers in primary and secondary schools, promotes Open Schooling methodologies and fosters interaction with scientists and experts in the field. This direct engagement enhances students' understanding of ocean- and water-related topics and strengthens their connection to the places where they live, particularly their local waters
Effects of sea ice on Baltic Sea eutrophication
Get PDFThis study investigates the influence of sea ice on eutrophication in the Baltic Sea ecosystem by comparing
simulations from 1953 to 2017, with ice and without ice cover. We assessed the impact from ice cover by using
eutrophication indicators defined by the Marine Strategy Framework Directive (MSFD), the Dia/Dino index and
the newly proposed Trophic Transfer Index (TTI). Five out of six indicators suggest a negative impact of sea ice
on the eutrophication status of the Baltic Sea, with a marked increase in ice impact observed in the early 1970s,
followed by a decline in the late 1980s. The linear correlation between ice impact on MSFD indicators and
nutrient loads suggests that the influence of ice becomes more pronounced under conditions of elevated nutrient
loads. Around 1988, both the TTI and Dia/Dino index indicate eutrophication amplification, with ice cover
significantly impacting both indicators (approximately 30 %), leading to a shift towards dinoflagellate domi�nance. While ice influences plankton timing and ecosystem structure, nutrient loads remain the primary driver of
the timing of spring and summer blooms. According to our study the reduction in sea ice cover due to climate
change, could contribute to the faster achievement of the Baltic Sea’s Good Environmental Statu
Unusual coccolithophore blooms in Scottish waters
Get PDFTwo unusual blooms were observed in Scottish waters during summer 2021: one in the Clyde Sea and the other by the east coast of the Shetland Islands. Both had the appearance of coccolithophore blooms. Transmission electron microscopy of a sample from the Clyde Sea confirmed the presence there of the coccolithophore Emiliania huxleyi. We examine the conditions that led to these unusual blooms. In situ data are scarce, and so we draw inference from satellite data and reanalysis. For Shetland, the bloom can be seen to originate further north on the edge of the continental shelf. It is advected south and then west towards the Shetland coast by surface currents. For the Clyde Sea region, April 2021 was the coldest April of the last 30 years (National Climate Information Centre). We hypothesise that this cold weather restricted the usual spring bloom of diatoms. A restricted spring bloom would mean higher-than-usual concentrations of nutrients in the summer. It might also mean reduced numbers of grazers. These factors would provide ideal conditions for coccolithophores to flourish as temperatures and sunlight increase