Project

Commercial service platform for user-relevant coastal water monitoring services based on Earth observation (CoastObs)

Goal: CoastObs will develop a service platform for coastal water monitoring with validated products derived from EO. In dialogue with users from various sectors, CoastObs will establish innovative EO-based products: monitoring of seagrass and macroalgae, phytoplankton size classes, primary production, and harmful algae as well as higher level products such as indicators and integration with predictive models. For these products, CoastObs will establish sustainable supply chains that can be directly integrated into the users’ systems.

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Project log

Pierre Gernez
added a research item
Seagrass meadows are monitored in the frame of several environmental programs worldwide, including the Water Framework Directive (WFD), to evaluate the ecological status of European coastal and transitional water bodies. The large size, spatial complexity, and interannual variability of seagrass ecosystems significantly challenge field monitoring. In this study, a multi-mission satellite time-series was used to estimate long-term changes in seagrass status in a macrotidal system dominated by Zostera noltei, at Bourgneuf Bay (French Atlantic coast). Metrics of seagrass extent and density were obtained from Earth Observation (EO) using validated and inter-calibrated Landsat, SPOT and Sentinel2 data from 1985 to 2020. The information provided by satellite data made it possible to compute and compare several seagrass indicators currently in use in several European countries (France, Portugal and UK) within the WFD. Both the seagrass extent and meadow-averaged density displayed increasing trends since 1985. A time-series of merged observations from various satellites revealed a high degree of interannual variability in seagrass extent, with abrupt losses (up to 50% within one year) alternating with periods of slow recovery (typically 4–6 years). The seagrass meadow which was in a moderate status (sensu the WFD) in the 1980s, achieved an overall recurrent good or high status since the mid-1990s. Altogether, the methods and results presented here demonstrated that EO is a reliable source of information for mapping and assessing the status of intertidal seagrass, complementing in situ measurements by providing long-term, spatial view and standardized observation framework. We recommend the systematic use of EO time-series in complement to traditional field measurements in seagrass monitoring programs such as the WFD.
Barillé Laurent
added 2 research items
Earth-observations applications to water quality are presented with two studies related to the Water Framework Directive. The first funded by the French Agency of Biodiversity explores the possibility of using microphytobenthos as a biological indicator of the ecological status of transitional waters. The second one developed in the H2020 CoastObs project, illustrates the calculation of intertidal seagrass Ecological Quality Ratio using satellite data. One application for the monitoring of coastal biodiversity is presented through the BiCOME ESA-funded project led by the Plymouth Marine Laboratory and starting in October 2021: Biodiversity of the coastal ocean: monitoring with Earth Observation.
The Earth-observation based products are in the CoastObs portal: https://coastobs.lizard.net. Login details to the portal will be provided after finalising the CoastObs training materials: https://coastobs.eu/e-training Products in the portal include demonstration products of the following parameters: Basic products: Chl-a Suspended matter Turbidity Sea surface temperature Innovative and higher level products: Sea grass percentage coverage Phytoplankton size classes Harmful algae bloom (HAB) indicators for Pseudonitzschia and Alexandrium (Mean) food quality for shell fish Mussel growth potential Relative growth rate (of mussels) There are products for the following areas: Loire Estuary (France) Bourgneuf Bay (France) Eastern Scheldt + Voordelta (Netherlands) Wadden Sea (Netherlands) Venice Lagoon (Italy) Galician coast (Spain) Rias Baixas (Spain) In the portfolio are more products, such as: Primary production WFD indicators HAB forecasts Plume morphology Phytoplankton bloom morphology
Federica Braga
added 4 research items
The coexistence of phytoplankton and macrophytes in the Lagoon of Venice (Northern Adriatic Sea, Italy) was investigated using in situ data collected monthly as part of International Long Term Ecosystem Research (LTER), together with satellite imagery for the period 1998–2017. The concentrations of chlorophyll a and hydrochemical parameters were measured in three areas of the lagoon, where the expansion of well-developed stands of submerged vegetation was observed by remote sensing. Our results suggest interaction between phytoplankton and macrophytes (macroalgae and seagrasses) in the last few years of the time series, evidenced by decreasing chlorophyll a concentrations in the vicinity of the macrophyte stands. The integration of LTER and remotely sensed data made it possible to evaluate the interaction of macrophytes and phytoplankton at the ecosystem scale for the first time in the Lagoon of Venice.
Satellite imagery provides evidence of complex mixing dynamics in the coastal zone in front of multiple mouth deltas. One peculiar feature, identified in front of the Po Delta (Italy), consists in warmer water bulges present in some periods in the coastal zone between the river mouths. Such features are evident during both high and low river discharge. Through an integrated approach based on the analysis of satellite imagery, in situ field data and a high-resolution oceanographic model, representing the whole river-delta-sea system, we investigated the relative contribution of the different forcing in controlling coastal mixing of riverine waters. The results evidence that the occurrence of these warmer saltier water bulges is due to upwelling induced by the combined action of tides and wind regimes aligned along coastline. Winds from the land and along the coast drive the upwelling through the well-known mechanism described by Ekman. The presence of river discharge enhance the water column stratification, creating the conditions in which tidal action follows the tidal straining theory. Both processes are identified in modelling results. The occurrence of these localized coastal waters with peculiar thermohaline characteristics, detectable on satellite imagery of the area, can be relevant in the definition of the freshwater areas of influence and the mechanisms of riverine water mixing in the near coastal zone. This can shed some light, eventually, on characterizing the sediment dynamics, as well as the thermohaline properties of waters in the area, and also to identify eventual impacts on the local ecosystems and fishery.
The lagoon of Venice has always been affected by the regional geomorphological evolution, anthropogenic stressors and global changes. Different morphological settings and variable biogeophysical conditions characterize this continuously evolving system that rapidly responds to the anthropic impacts. When the lockdown measures were enforced in Italy to control the spread of the SARS-CoV-2 infection on March 10th 2020, the ordinary urban water traffic around Venice, one of the major pressures in the lagoon, came to a halt. This provided a unique opportunity to analyse the environmental effects of restrictions to mobility on water transparency. Pseudo true-colour composites Sentinel-2 satellite imagery proved useful for qualitative visual interpretation, showing the reduction of the vessel traffic and their wakes from the periods before and during the SARS-CoV-2 outbreak. A quantitative analysis of suspended matter patterns, based on satellite-derived turbidity, in the absence of traffic perturbations, allowed to focus on natural processes and the residual stress from human activities that continued throughout the lockdown. We conclude that the high water transparency can be considered as a transient condition determined by a combination of natural seasonal factors and the effects of COVID-19 restrictions.
Laura Zoffoli
added a research item
Accurate habitat mapping methods are urgently required for the monitoring, conservation, and management of blue carbon ecosystems and their associated services. This study focuses on exposed intertidal seagrass meadows, which play a major role in the functioning of nearshore ecosystems. Using Sentinel-2 (S2) data, we demonstrate that satellite remote sensing can be used to map seagrass percent cover (SPC) and leaf biomass (SB), and to characterize its seasonal dynamics. In situ radiometric and biological data were acquired from three intertidal meadows of Zostera noltei along the European Atlantic coast in the summers of 2018 and 2019. This information allowed algorithms to estimate SPC and SB from a vegetation index to be developed and assessed. Importantly, a single SPC algorithm could consistently be used to study Z. noltei-dominated meadows at several sites along the European Atlantic coast. To analyze the seagrass seasonal cycle and to select images corresponding to its maximal development, a two-year S2 dataset was acquired for a French study site in Bourgneuf Bay. The potential of S2 to characterize the Z. noltei seasonal cycle was demonstrated for exposed intertidal meadows. The SPC map that best represented seagrass growth annual maximum was validated using in situ measurements, resulting in a root mean square difference of 14%. The SPC and SB maps displayed a patchy distribution, influenced by emersion time, mudflat topology, and seagrass growth pattern. The ability of S2 to measure the surface area of different classes of seagrass cover was investigated, and surface metrics based on seagrass areas with SPC ≥ 50% and SPC ≥ 80% were computed to estimate the interannual variation in the areal extent of the meadow. Due to the high spatial resolution (pixel size of 10 m), frequent revisit time (≤ 5 days), and long-term objective of the S2 mission, S2-derived seagrass time-series are expected to contribute to current coastal ecosystem management, such as the European Water Framework Directive, but to also guide future adaptation plans to face global change in coastal areas. Finally, recommendations for future intertidal seagrass studies are proposed .
Barillé Laurent
added a research item
Executive summary and recommendations The EU Water Framework Directive 1 (WFD) is an ambitious legislation framework to achieve good ecological and chemical status for all surface waters and good quantitative and chemical status for groundwater by 2027. A total of 111,062 surface waterbodies are presently reported on under the Directive, 46% of which are actively monitored for ecological status. Of these waterbodies 80% are rivers, 16% are lakes, and 4% are coastal and transitional waters. In the last assessment, 4% (4,442) of waterbodies still had unknown ecological status, while in 23% monitoring did not include in situ water sampling to support ecological status assessment 2. For individual (mainly biological) assessment criteria the proportion of waterbodies without observation data is much larger; the full scope of monitoring under the WFD is therefore still far from being realised. At the same time, 60% of surface waters did not achieve 'good' status in the second river basin management plan and waterbodies in Europe are considered to be at high risk of having poor water quality based on combined microbial, physical and physicochemical indicators 3. Water quality metrics derived from satellite observation can complement conventional water sampling, particularly to achieve much improved spatial and temporal coverage of medium (several square kilometres) and larger waterbodies. Thus, it has the potential to enhance confidence in WFD ecological status classification, firstly by quantifying elements of environmental status that are currently not or under-reported by Member States, such as the frequency, onset, duration and extent of phytoplankton blooms. Second, confidence in ecological status assessment would improve with increased representativeness of the natural diversity of waterbodies that are monitored, their inter-annual variability and water quality trends within larger waterbodies. Moreover, using standardised approaches, it would allow better comparison and standardization of water quality assessment across Member States, facilitating the management of transboundary waters in particular. Finally, by increasing spatial and temporal coverage, satellite observation is expected to enhance the effectiveness of the Programme of Measures (PoM) through early detection of deterioration, improving knowledge of the potential extent of an impact, improving monitoring of the effectiveness of PoMs and providing information to support more strategic in situ sampling. The European Union and European Space Agency currently boast the most advanced suite of satellite-based instruments designed to observe optical water quality. The Copernicus framework of sensors and services has had significant investment in recent years. Therefore, the vast majority of the cost associated with satellite-based monitoring of surface waters has already been invested. To promote and support the use of satellite-based water quality metrics in WFD national and statutory monitoring and reporting activities, we make the following recommendations, particularly in light of the ongoing revision of the WFD: Recognition of satellite observation as an assessment method in the context of the revision of the Water Framework Directive.
Evangelos Spyrakos
added a research item
The NW coast of the Iberian Peninsula is dominated by extensive shellfish farming, which places this region as a world leader in mussel production. Harmful algal blooms in the area frequent lead to lengthy harvesting closures threatening food security. This study developed a framework for the detection of Pseudo-nitzschia blooms in the Galician rias from satellite data (MERIS full-resolution images) and identified key variables that affect their abundance and toxicity. Two events of toxin-containing Pseudo-nitzschia were detected (up to 2.5 μg L−1 pDA) in the area. This study suggests that even moderate densities of Pseudo-nitzschia in this area might indicate high toxin content. Empirical models for particulate domoic acid (pDA) were developed based on MERIS FR data. The resulting remote-sensing model, including MERIS bands centered around 510, 560, and 620 nm explain 73% of the pDA variance (R2 = 0.73, p < 0.001). The results show that higher salinity values and lower Si(OH)4/N ratios favour higher Pseudo-nitzschia spp. abundances. High pDA values seem to be associated with relatively high PO43, low NO3− concentrations, and low Si(OH)4/N. While MERIS FR data and regionally specific algorithms can be useful for detecting Pseudo-nitzschia blooms, nutrient relationships are crucial for predicting the toxicity of these blooms.
Caitlin A. L. Riddick
added a research item
Evaluation of Sentinel-2 and -3 water quality products over European coastal and transitional waters, including chlorophyll-a, seagrass density, primary productivity, phytoplankton size classes, and harmful algal bloom detection.
Kathrin Poser
added an update
Our project website has been launched! Visit us at http://coastobs.eu/
You can also follow us on Twitter https://twitter.com/coastobsproject or Facebook https://www.facebook.com/CoastObs/
 
Kathrin Poser
added a project goal
CoastObs will develop a service platform for coastal water monitoring with validated products derived from EO. In dialogue with users from various sectors, CoastObs will establish innovative EO-based products: monitoring of seagrass and macroalgae, phytoplankton size classes, primary production, and harmful algae as well as higher level products such as indicators and integration with predictive models. For these products, CoastObs will establish sustainable supply chains that can be directly integrated into the users’ systems.