2.1 Format of questionnaire

The questionnaire (Fig. 2; for more detail see the Supplement Sect. S1) was developed using Google Forms and consisted of two linked forms. The first form was focussed on obtaining the views of all respondents on the environmental threats in European waters and the adequacy of current monitoring programmes. Maps were provided to ensure consistency in participant selection of “regions of interest” (see Sects. S2 and S3). For questions related to pressures and impacts, respondents could select one or more responses from lists provided. They could also add free text in order to provide detail or explanations of their responses. Questions related to the adequacy of existing monitoring programmes included comment boxes for free text to allow respondents to give their views on those monitoring programmes which were not adequate or only partly adequate for addressing environmental threats and suggestions on how to improve the monitoring of the threats identified.

The second form was focussed on national monitoring programmes, with the aim of obtaining a summary of sampling platforms used, variables measured, monitoring frequency, and the duration of the programme. This form included a section on data accessibility.

An invitation to participate in the poll and complete the questionnaire was sent to all partners in JERICO-NEXT in June 2016 and subsequently forwarded to wider contact networks. It was closed to responses in November 2016.

Figure 2Format of online questionnaire.

Download

2.2 Data analysis

Once the poll was closed, responses were downloaded from Google Forms and stored in an MS Access database. Identifying information was removed from the responses to anonymize the data. More than one response was received from some countries. Results on views or opinions on environmental threats and impacts and on monitoring programmes were analysed using responses by country; i.e. categorial responses were aggregated by country, counting each response if it appeared at least once in the individual responses for the country. Marine litter, for example (see Sect. 3), was identified as a threat or pressure in all of the national responses; however, it was not identified in every single individual response for each country where there were multiple responses. The aggregated responses are referred to hereafter as “national responses”.

Details of monitoring programmes and expert opinions on the adequacy of monitoring programmes were analysed for all respondents. Opinions were also analysed within each country. Free-text responses from all respondents on the adequacy of monitoring programmes were extracted to summarize all opinions given, as were the suggestions for improving monitoring programmes that were not adequate or partly adequate to address environmental threats.

To visualize the most common themes emerging from the questions on why monitoring programmes were inadequate, word clouds were created using an online software tool (Wordle, 2018) which emphasizes the most common responses from individuals according to how many times they are mentioned.

3.1 Respondents

The online questionnaire was completed by representatives from 12 European countries (Finland, France, Germany, Greece, Ireland, Italy, Malta, Norway, Poland, Spain, Sweden, UK; Fig. 1) representing different regional seas (Fig. 3) and their subregions (see Sects. S2 and S3). From some countries, responses were received from more than one respondent, resulting in a total of 36 responses from the 12 countries. The most responses (14) were received from the UK and covered territorial waters (12 nm) as well as their Exclusive Economic Zone (EEZ) waters. Five responses were received from Greece, six from France, two from Spain, and two from Malta. Many respondents were JERICO-NEXT partners, but some were also from the wider European monitoring network. Two responses were received from people in organizations which represent multiple countries (see S3, Table S3.1). From EuroGOOS, a Swedish representative answered from a Swedish perspective. From OSPAR, a UK-based person answered for the region as a whole.

To reduce bias in the results due to different numbers of respondents from each country, views on threats, impacts, and adequacies of monitoring programmes were aggregated to give one response per country. This was considered to represent a national response (see Sect. 2.2). Data analysis showed weak relationships between the number of pressures or impacts identified per country and the number of responses per country (data not shown).

3.2 Views on environmental threats and impacts

3.2.1 Pressures from human activities

Marine litter was identified as a pressure in all of the national responses (Fig. 4). The next most commonly identified pressures were shipping (92 %), contaminants (92 %) organic enrichment (83 %), and fishing (75 %, Fig. 4). These were followed by regime change (67 %), inorganic nutrient enrichment and aquaculture (both 58 %, Fig. 4), dumping and aggregate extraction (50 %), and atmospheric inputs, dredging of biota, and construction or obstruction (all 42 %). Activities such as mining, water abstraction, the oil and gas industry, and coastal squeeze scored considerably lower, at 10 %–23 % of responses. Only one extra pressure was added to the list provided, unexploded ordnance (UXO).

Respondents noted that the pressures affecting coastal and offshore areas were not the same. Climate-change-related pressures (regime change and ocean acidification) were considered to have large potential for widespread harm, and in all sea regions at least one respondent marked regime change as an important pressure. Thermally-driven regime change was selected in a greater proportion of responses than salinity-driven regime change.

Figure 3The regional seas represented by respondents to the questionnaire. See the Supplement for maps of regions (S2) and subregions of European seas (S3).

3.2.2 Impacts of the pressures identified

The majority of national responses (> 70 %) identified habitat loss or destruction, underwater noise, and contamination as the main impacts of human activities on the marine environment (Fig. 5). Approximately 60 % of national responses identified undesirable disturbance (e.g. oxygen depletion), sediment or substrate composition, changes in community composition, harmful microorganisms, and invasive species as impacts. Half (50 %) identified changes in primary production, changes in species range, population change or depletion of standing stocks, biofouling, physical damage, changes in suspended sediments or turbidity, and mortality of marine life.

Figure 4Frequency of national responses on pressures affecting the marine environment.

Download

Figure 5Frequency of national responses on impacts affecting the marine environment.

Download

3.3 Views on the main drivers of marine monitoring

3.3.1 Policy purposes

The majority of national responses (83 %) identified the main drivers of the monitoring of coastal and offshore waters as the Water Framework Directive (WFD, EU, 2000) and the Marine Strategy Framework Directive (MSFD, EU, 2008, Fig. 6). Other EU directives were identified but the proportion of national responses identifying these as policy purposes for monitoring was relatively low. A total of 25 % of national responses included the Urban Waste Water Treatment Directive (EC, 1991a) and Habitats and Birds Directive (Fig. 6), and 17 % included the Bathing Waters Directive and the Nitrates Directive (EC, 1991b). Regional Seas Conventions were also identified as drivers of marine monitoring, with OSPAR identified by 67 % of national responses and HELCOM identified by 17 % of national responses. Local policy drivers were identified by 58 % of national responses, but no details were given.

Respondents were asked to link environmental threats in European waters to the descriptors (D) in the MSFD (Fig. 7; see EU, 2008). Responses indicated that most threats (92 %) affect the biodiversity descriptor (D1, Fig. 7). The next most frequent responses (83 %, Fig. 7) were linked to descriptors for contaminants (D8), eutrophication (D5), and marine litter (D10); 75 % of threats could be linked to the energy descriptor (D11), 67 % to sea-floor integrity (D6), hydrographic conditions (D7), and non-native species (D2), and 50 % to food webs (D4).

Figure 6Main policy or other drivers for marine monitoring.

Download

Figure 7MSFD descriptors linked to environmental threats. The left axis shows the descriptor number and name.

Download

3.4 Monitoring programmes in each country

In total, 36 responses on the monitoring section of the questionnaire were received from the 12 countries who participated in the online poll; 38 monitoring programmes were reported. More than half of these programmes were official or statutory programmes, and a significant proportion (28 %) were project based rather than statutory. These included the Balearic Islands multi-platform observing system (SOCIB), the UK BeachWatch litter project, and projects in Ireland (Smartbay observatory).

This is not a complete inventory of monitoring in Europe, but the responses provide examples of a variety of monitoring programmes. Entries for the UK, Ireland, and Greece appeared to be relatively comprehensive.

3.4.1 Monitoring: variables, platforms, and frequency

Most monitoring programmes were reported to measure temperature and salinity. A large proportion of responses (39 %–45 %, Fig. 8) reported measurements of nutrients, chlorophyll, and dissolved gases, although not all parameters are measured at all stations in a monitoring programme. Many variables, such as mammals, birds, biotoxins, and marine litter, are only measured in specific monitoring programmes designed for the purpose. Some variables are monitored in only a few monitoring programmes, e.g. sea level and contaminants, but this may reflect the selection of responses received. Responses to the questionnaire indicated that marine monitoring programmes provide less coverage of biological parameters (e.g. plankton 32 %, fish 18 %, benthos 18 %, macroalgae 11 %, birds 3 %) than physical water column parameters (e.g. temperature, salinity, 58 %–61 %) and chemical parameters (e.g. nutrients, dissolved gases, 45 % and 39 %).

Figure 8Variables measured in marine monitoring programmes.

Download

Most monitoring programmes were reported to use a vessel as a monitoring platform (Fig. 9), usually a research vessel or, for inshore monitoring, a small boat. Shore-based monitoring was also common (39 %). The use of fixed platforms was indicated by 34 % of respondents, including those from Belgium, Greece, Ireland, Italy, Spain, and the UK. The use of remote sensing as a monitoring platform was reported by 21 % of respondents (Fig. 9). Other innovative and emerging technologies, such as autonomous vehicles, FerryBoxes, and “other” (e.g. profiling floats), were included in ≤11 % of the responses (Fig. 9).

Figure 9Platform types used in marine monitoring.

Download

Responses to the questionnaire indicated that monitoring frequency (Fig. 10) is variable. The highest proportion of responses (34 %) was for continuous monitoring (e.g. from fixed platforms, moorings, or gliders). Several monitoring programmes were reported to have only annual monitoring, but to be comprehensive in terms of parameters and spatial coverage. Monitoring programmes incorporating fixed platforms or gliders were more restricted in terms of spatial coverage.

Figure 10Frequency of monitoring. The main graph shows results for all options given in the questionnaire. The inset combines these into three categories: continuous and intermittent are the same as in the main graph, and “regular” indicates that all other options are combined.

Download

3.5 Gaps identified in current monitoring programmes

In terms of providing the information required to monitor environmental threats, 12 % of all the respondents to the questionnaire considered monitoring programmes to be adequate, while 28 % indicated that monitoring programmes were not adequate, and 60 % considered monitoring programmes to be partially adequate (Fig. 11).

Figure 11Proportion of all respondents who considered their monitoring programmes to be adequate (yes), inadequate (no), or partly adequate (partly).

Download

When there was more than one respondent per country, responses were varied (Fig. 12), with the majority of responses indicating inadequate monitoring. In the UK, for example, from which 14 responses were received, most responses (57 %) indicated that monitoring was partly adequate and 29 % that monitoring was not adequate. Two respondents (15 %) felt that monitoring programmes were adequate. In France, from which six responses were received, the majority (83 %) considered monitoring not adequate, and the remaining one felt it was adequate. In Greece, four out of five respondents (80 %) felt monitoring was not adequate, and one considered it to be partly adequate. In countries with two responses (Italy, Malta, and Spain), one indicated that monitoring was not adequate, while one felt it was partly adequate. In countries with one respondent, responses mostly indicated that monitoring was partly adequate (Finland, Ireland, Norway, Sweden). In Poland, the national representative reported that monitoring was adequate.

Figure 12Responses by country showing the proportion of respondents who considered their monitoring programmes to be adequate (yes), inadequate (no), or partly adequate (partly). The number of respondents per country ranged from 1 to 14 (see numbers in bold).

Download

Where monitoring is not adequate

Responses were focussed around a few key issues (see Fig. 13) which appeared to be related mostly to insufficient resolution in time and space, insufficient data or parameters measured, and lack of integration (e.g. of monitoring programmes, indicators, and descriptors).

A number of respondents stated that there is insufficient monitoring for some of the MSFD descriptors. These descriptors included biodiversity, food webs, marine litter (including microplastics), underwater noise, emerging contaminants, and emerging pollutants. However, no details were given. It was noted that coupling between physics and biology in response to environmental pressures is typically not included in monitoring programmes focussed on individual descriptors. One respondent indicated that methodologies and approaches were not state of the art; for example, the focus during benthic sampling was on taxonomy instead of ecosystem functions and services.

Figure 13Keywords used in views on partially adequate or inadequate monitoring programmes. Font sizes indicate the most common responses from individuals according to how many times they are mentioned.

Two respondents highlighted concerns about the links to policy drivers, suggesting that monitoring was reactive rather than proactive. One of these respondents commented that monitoring programmes develop to respond to pressures and impacts. The other highlighted concerns related to unexploded ordnance, for which there seems to be very little political or commercial interest in finding and making safe dumped munitions until a person or marine organism is found with injuries or abnormal growth.

Examples of monitoring programmes with low spatial resolution were given for point source monitoring of contaminant inputs, controls and improvements, benthic habitats for the wider environment and deep-sea areas, and subregions of the Mediterranean Sea. Examples of inadequate monitoring of parameters were given for the Mediterranean Sea, including zooplankton, phytoplankton compositions, marine mammals, reptiles, birds, invasive species, marine litter, and contaminants in sediment and biota.

5.1 Polling approach

The opinion poll carried out during this study had a limited number of participants, as it was targeted towards scientists and managers with the relevant expertise and experience in European countries adjoining regional and/or subregional seas. In order to minimize bias which might be introduced by some countries providing more individual responses than other countries, project partners were expected to develop national responses and were given approximately 5 months to do so. When there was more than one response from a country, results on views or opinions were combined to represent a national view.

Responses on monitoring programmes were not combined, as these were considered to provide useful detail on gaps in monitoring, and no monitoring programmes had duplicate responses.

Despite a number of limitations in the polling approach, responses provided valuable insights on the environmental pressures and their impacts, as well as on gaps in monitoring the impacts. A recent study in estuaries and coastal waters in the North Sea–Baltic Sea transition zone (Andersen et al., 2019) using 35 databases yielded results which are broadly similar (see below).

5.2 Drivers of marine monitoring

Most national responses were focussed on policy drivers such as EU directives and regional conventions based on the ecosystem approach. These responses are likely to have been influenced by the overall context of the JERICO-NEXT project and its emphasis on biogeochemical processes and the coupling between physics and biology. Responses may also have been influenced by the drop-down list of options from which to select answers, although the option was given to add responses.

Interestingly, local drivers scored quite highly. No details or examples were given by any of the respondents but may include monitoring towards impact assessments for a variety of reasons, such as the development of local fisheries or recreational activities, or to meet conservation objectives (e.g. for marine protected areas). However, such monitoring would be included under policy drivers such as the Habitats and Birds Directives or marine planning, and relatively few responses (≤25 %) indicated these as drivers for marine monitoring. It is possible that local drivers included research projects or programmes, but this seems unlikely as the poll was focussed on monitoring rather than research. This highlights a potential weakness of the aims of this study and indeed the JERICO-NEXT project, as it did not include an objective to identify gaps in understanding and how to provide better linkages between research and monitoring. Certainly, ongoing national monitoring programmes are focussed on reporting to directives and international obligations, and not to contribute to a better understanding of the possible impacts of the threats.

Complex linkages between pressures and impacts and the cumulative effects of multiple pressures are not currently well addressed by any of the reported monitoring programmes. The MSFD was intended as a holistic approach to assessments, but descriptors are currently assessed separately. Developments are underway to move assessments towards a more integrated cross-disciplinary ecosystem approach both in Europe (e.g. OSPAR¹²; EEA, 2011, 2015b; HELCOM, 2018) and globally (Schmidt et al., 2019). This will require more coordinated monitoring across descriptors and a focus on acquiring long-term datasets, particularly for addressing cross-cutting issues such as climate change and ocean acidification (Tett et al., 2013; Schmidt et al., 2019). Responses indicating that a number of monitoring programmes have been running for more than 10 years are extremely positive, providing data to allow for the detection of temporal trends in pressures and their impacts on the marine environment. Evidence that a significant proportion of monitoring is largely project based rather than statutory indicates some degree of risk to the sustainability of monitoring. EuroGOOS conducted a survey of sea level monitoring and found similar issues; less than half of the organizations responding indicated that there were no funding issues for tide gauges, and many had reduced funding or uncertain future funding (EuroGOOS, 2017). Similar issues are encountered in other parts of the world where monitoring is supported by both academic and private research and hampered by a lack of sustained funding from governments from which grants are often short term (Weller et al., 2019).

With the majority of responses to the online poll indicating that the main policy drivers of current monitoring are the MSFD and WFD, rather than earlier directives such as the Urban Waste Water Treatment Directive (UWWTD), the Nitrates Directive, and the Habitats Directive, it is clear that policy drivers and requirements for meeting policy needs change over time. This suggests that monitoring programmes should be underpinned by high-level scientific objectives and that research and monitoring should be well integrated. Data sharing, such as through the JERICO-NEXT research infrastructure, coastal observatories, and the EMODNet data infrastructure (Miguez et al., 2019), is vital to the current and future integration of research and monitoring (Farcy et al., 2019). Furthermore, the availability of data at local and regional scales is essential for the development of future monitoring and assessment approaches, particularly as new technologies and assessment tools are developed and become more readily available (e.g. Borja et al., 2019; García-García et al., 2019).

5.3 Views on environmental threats and impacts

Respondents were provided with comprehensive lists of key environmental threats and impacts informed by previous studies, with an option to add to the list. One item, UXO, was added to the list of pressures by one country. This pressure was considered to be outside the scope of the JERICO-NEXT project but may be useful in other contexts. No new items were added to the list of impacts in the national responses.

The most commonly identified pressures or threats to the marine environment due to manageable human activities were considered to be marine litter, shipping, contaminants, organic enrichment, fishing, and regime change.

The main impacts of threats to the marine environment (i.e. > 70 % of national responses) were identified to be habitat loss or destruction, underwater noise, and contamination. A total of 60 % of national responses identified impacts to be undesirable disturbance (e.g. oxygen depletion), changes in sediment or substrate composition, changes in community composition, harmful microorganisms, and invasive species.

In a recent study, Andersen et al. (2019) analysed 35 publicly available datasets from Danish marine waters and obtained broadly similar results. These authors found the main stressors (pressures) across a range of water types to be nutrients, climate anomalies, non-indigenous species, noise, and contaminants. Some stressors (e.g. fisheries, contaminants, noise) were shown to have a relatively higher impact in open waters, while some stressors (e.g. nutrients, shipping, physical modification) had a relatively higher impact within fjord or estuarine systems. Some of these stressors (pressures) were considered to be impacts in this study, e.g. non-indigenous (invasive) species. It was recognized that it can be difficult at times to distinguish between pressures and impacts. For example, shipping is a pressure and one of its impacts can be the introduction of invasive species via ballast water, but these invasive species can themselves become a pressure on the native ecosystem.

5.4 Monitoring programmes

Most respondents were of the view that current monitoring is partially adequate or not adequate. The range of views given between and within countries suggest that a broad spectrum of participants responded to the questionnaire (Fig. 12). These views likely reflect the different experiences of respondents in their areas of expertise and in their countries.

Key issues identified in responses (i.e. insufficient resolution in time and space, insufficient data or parameters measured, and lack of integration) indicate gaps in monitoring. Suggestions for improved monitoring programmes were targeted at these gaps and need to be considered in detail to feed into science and monitoring strategies. These issues are discussed in Sect. 5.5.

Few respondents completed the second questionnaire on monitoring programmes, so a subset of European monitoring programmes was reported. The opinions may therefore reflect the views of the JERICO community, particularly on the measurement of limited parameters (with a focus on physical and biogeochemical parameters, e.g. temperature, salinity, and chlorophyll). These views are supported by information available via a number of projects and infrastructures (e.g. JERICO, DEVOTES, COPERNICUS, EMODnet, EMSO ERIC, and AtlantOS; links given in Sect. 1), all of which indicate the need to improve the availability of datasets, especially biological components (e.g. fish, seabirds, and mammals). Furthermore, limited monitoring of pressures indicates some mismatch between the pressures and impacts considered by respondents to be important and those actually monitored.

Several programmes were reported to be making use of alternative platforms such as remote sensing, autonomous vehicles, and FerryBoxes. These technologies are likely to complement other monitoring platforms (e.g. boat based) rather than replace them altogether. Remote sensing data, for example, are limited to surface monitoring of particular parameters and still require in situ data for calibration and validation (Groom et al., 2019). FerryBox monitoring can improve coverage in space and time (e.g. Grayek et al., 2011) but is similarly limited in terms of depth and parameters (Petersen, 2014).

Suggestions given for improving monitoring programmes are supported by many studies on the development of existing and new technologies. Davidson et al. (2019) provide an overview of the need for operational oceanographic systems, which include a multi-platform observation network, as well as systems for data management, data assimilation and prediction, and data dissemination and accessibility. Key components of such systems include an integrated approach (She et al., 2019), partnerships and shared approaches for monitoring, assessment and data (Bax et al., 2019; Canonico et al., 2019; Míguez et al., 2019; Schmidt et al., 2019; Stammer et al., 2019; Tanhua et al., 2019; Weller et al., 2019), instrumented moorings (fixed platforms; Bailey et al., 2019), and new methodologies for monitoring, including in situ biochemical, biological, and molecular sensors (reviewed by Wang et al., 2019).

5.5 Resolution in time and space

The scale of impacts varies widely, with some activities, such as the construction of a wind farm, having a potentially high impact on a small area, whereas activities such as fishing are more widespread. The impact of human activities also depends on the vulnerability of the habitat in question. For example, in the southern Celtic Sea, fragile benthic habitats with cold-water corals are highly impacted by sea-floor activities. Some impacts, such as noise disturbance, depend on the intensity of the activity and will be concentrated in areas with high shipping activity or during periods of construction.

Countries such as the UK adopt a risk-based monitoring approach, which was considered to result in fragmented monitoring. Examples of low spatial resolution were given for the Continuous Plankton Recorder (CPR) survey, one of the key plankton datasets, for which spatial gaps exist throughout EU waters. Spatial resolution was also considered to be low for some habitats, as not all habitats are covered by monitoring programmes, and for monitoring of marine litter and non-native species.

In terms of spatial resolution, other responses indicated that not all parameters are monitored adequately. Even for parameters that were reported as monitored in many monitoring programmes, e.g. chlorophyll (47 % of reported programmes), monitoring may not be adequate in space or time (see Baretta-Bekker et al., 2015, Annex 1¹³). A more detailed analysis looking at the distribution of the monitoring of different parameters in space would be required to assess this. The WFD does not require zooplankton monitoring, but some indicators under the MSFD do require information on zooplankton. Although phytoplankton is monitored inshore, the data are disparate and mainly used to report on potential health issues due to toxin-producing algae.

For temporal resolution, examples were given for a number of threats where the monitoring period was considered to be inadequate. For example, for statutory monitoring of impacts such as those from dredging and disposal, monitoring is often over timescales which are too short (2–5 years) to properly assess the impacts on the biological communities. This also applies to seabird and cetacean monitoring, which is out of the scope of JERICO-NEXT. Some monitoring programmes may be inadequate in terms of temporal frequency: 24 % of monitoring programmes reported had annual monitoring, which may fail to detect impacts throughout the year. Monitoring frequency is likely to be strongly influenced by platform types, with increasing use of fixed platforms, moorings, or gliders giving a high proportion (34 %, Fig. 10) of responses for continuous monitoring. Certainly, platforms such as moorings can provide high-frequency temporal resolution (e.g. Mills et al., 2005; Greenwood et al., 2010) for the parameters they measure, predominantly physical and chemical parameters (such as temperature, salinity, light, dissolved oxygen) with biological parameters limited to phytoplankton fluorescence or chlorophyll. Monitoring more complex biological parameters (such as community species composition in the benthic and/or pelagic compartments) at high frequency appears particularly challenging because of the limited degree of development of appropriate semi-automatic tools. To date, routinely using such techniques at a high frequency of acquisition would still require a massive level of skilled manpower, although new developments of molecular tools would clearly help to tackle the challenge in the future. Additionally, even where low-cost sensors for biological parameters exist, analysing the large volumes of data produced remains a large challenge.

Addressing the issue of scales is essential in establishing a future pan-European monitoring programme, particularly for biological parameters. Monitoring these parameters is more limited than for physical parameters. The reasons for this include the following.

1. The types of biological data that can be automatically or semi-automatically acquired is low despite recent technological developments (including those achieved within FP7-JERICO and JERICO-NEXT), which limits the spatio-temporal coverage of biological or biogeochemical datasets.

2. Miniaturization of sensors allowing for implementation on platforms such as autonomous underwater vehicles (AUVs) and floaters is more feasible for physical and chemical parameters, which results in better spatial and synoptic coverage.

3. Scaling up from “point” observations to wider areas most often relies on modelling. Physical models are more advanced than biogeochemical and biological models, which also increases the importance of scales of biological observations.