Regeneration of aquatic ecosystems loses momentum

Regeneracja ekosystemów wodnych traci impet

The turn of the year is an occasion for most of us to take stock. We make an examination of conscience in the area that concerns us most. I, in addition to other, more personal accounts, decided to check out what is splashing in the waters in connection with this year’s 20th anniversary of Poland’s entry into the European Union structure and the adoption of the Water Framework Directive regulations. The fundamental premise of the directive was to shape the water policies of member countries in such a way as to halt the degradation of waters and ensure the maintenance or restoration of their proper status within a certain time horizon. How has Europe dealt with this challenge? Unfortunately, on average.

Rapid water degradation at the end of the millennium

Despite (or perhaps because of) the fact that freshwater ecosystems provide humans with vital ecosystem services, including drinking water, water for food and energy production or recreational services, humans have been ruthlessly degrading them for centuries, a process that accelerated rapidly after World War II, during a period of increased economic development. According to the literature [1], there has been a significant increase in pressure on water in Europe in the post-war period, manifested by acidification due to sulfur emissions (peak around 1980), eutrophication due to excessive nitrogen and phosphorus fertilization (peak around 1988), and invasions by alien species, among others. as a result of the development of transportation (peaking around 1996), as well as emissions of pesticides, organic substances or so-called “greenhouse gases. new contaminants (nanoplastics and pharmaceuticals).

In addition, waters are being degraded as a result of hydromorphological transformation, excessive abstractions, invasion by alien species and climate change. In response to such a condition, it has become necessary to implement countermeasures to improve water quality and restore freshwater habitat, including more effective wastewater treatment and control of air emissions of pollutants. In the United States came the Clean Water Act (1972), and in Europe the Wastewater and Nitrates Directives (both 1991), and finally the EU Water Framework Directive (WFD, 2000).

Post-2000 optimism. I think it was premature

As expected, the implemented regulations in the first period actually led to a significant reduction in organic pollution and acidification. Over the past 50 years, the corrective actions and mitigation measures implemented have resulted in measurable improvements in freshwater quality and the restoration of its biodiversity in some areas of Europe, mainly in Scandinavian countries [2, 3]. It seemed that we were on our way to a complete restoration of Europe’s freshwater ecosystems.

Just a dozen years ago, around 2010, reports assessing the achievements of the framework after the first decade of its implementation were quite optimistic. The change in thinking about water not as a resource, but as a resource and a common good undeniably contributed to a plethora of initiatives for ecosystem restoration. Numerous publications appeared summarizing the achievements of EU countries in the development of biological methods of water assessment, their international intercalibration and the development of water monitoring networks [4, 5].

The progress in acquiring water status data at the scale of almost the entire continent, compared to the situation before the implementation of the WFD, has indeed been impressive. However, at that time, the implementation of directive-compliant water assessment methods was not yet advanced enough, and the measurement series were too short and spatially limited to allow assessment of the effectiveness of regulation. Now, after almost a quarter of a century, biological monitoring in Europe has already provided so much data that we can finally say “check!”

After 2010. Ecosystem regeneration loses momentum

Rivers are the most abundant and intensively monitored aquatic ecosystems, and the benthic macroinvertebrate communities that inhabit them are widely used as a sensitive and reliable indicator of water quality. It is hardly surprising, therefore, that it is on such data that an international team of researchers, led by Prof. Peter Haase, based an assessment of river biodiversity trends in Europe over the past half century. The researchers set out to estimate the change in abundance and taxonomic and functional diversity of freshwater invertebrate communities over the past 50 years. For this, they used data from 22 European countries and more than 1,800 sites surveyed between 1968 and 2020 (although the vast majority of the data was from after 1990).

Their analyses, using hierarchical Bayesian models, showed significant changes in invertebrate communities, including increases in abundance and taxonomic and functional diversity (functional guilds) at rates ranging from 0.73 to as much as 2.4 percent. annually, depending on the index. The authors interpret this phenomenon as a result of improved water quality as a result of better wastewater treatment (for example, following the implementation of the EU Wastewater Directive in 1991) and the decline or modernization of polluting industries, as well as habitat restoration efforts. This is confirmed, among other things, by the observed increase in the abundance of pollution-sensitive taxa such as mayflies (Ephemeroptera), pitchforks (Plecoptera) and caddisflies (Trichoptera), although the authors stress the need for further, more detailed analyses of changes in taxonomic composition.

Unfortunately, this improvement occurred mainly in the 1990s. and in the early 2000s, and after 2010. A deceleration of this trend is observed. This suggests that the measures currently being implemented are producing below expectations, with many rivers still in unsatisfactory or even poor condition.

And what does it look like in Poland?

The work cited unfortunately did not include data from Poland. To the best of my knowledge, in our country we currently do not have good comparative analyses that show trends in water status between planning cycles (six-year management periods that assess water status and implement corrective actions in accordance with river basin management plans). Therefore, I was tempted to make such an analysis, admittedly extremely simplified, but comparing water quality parameters(available on the GIOŚ website) for two consecutive cycles 2010-2015 and 2016-2021. In order not to compare “pears with apples,” of all the monitored water bodies, I included only a subset of those that were surveyed in both periods.

And what? And gucio! In the pool of more than 1,800 rivers and more than 400 lakes, with data available for both periods, the median values and quartile ranges of the basic indicators of eutrophication and salinity (total nitrogen, total phosphorus, water transparency and electrolytic conductivity) were almost identical, and the differences were highly statistically insignificant (p > 0.2). Biological assemblages were no different, with the exception of the phytoplankton index in IFPL rivers, which showed a statistically significant, albeit discrete, improvement. For the inquisitive, I include a table with statistics (without going into methodological nuances, just compare the absolute values). All in all, I don’t know whether we should be worried that it hasn’t improved or happy that it hasn’t gotten worse.

IndicatorRIVERS (n=1880)lakes (n=428)
2010-20152016-20212010-20152016-2021
Total phosphorus (mgTP l-1)0,16 (0,11-0,24)0,16 (0,10-0,24)0,056 (0,034-0,099)0,056 (0,035-0,103)
Total nitrogen (mgTN l-1)2,59 (1,80-3,86)2,62 (1,80-4,04)1,41 (0,98-2,01)1,27 (0,94-2,00)
El conductivity. on. (µS cm-1)476 (365-636)484 (373-660)337 (269-451)354 (278-474)
Water clarity (m)1,6 (0,9-2,9)1,6 (0,9-2,9)
Chlorophyll-a (µg l-1)21,7 (8,6-50,0)18,8 (9,8-43,5)
Phytoplankton indicator0,64 (0,51-0,77)0,60 (0,40-0,74)2,20 (1,23-3,42)2,25 (1,24-3,27)
Phytobenthic indicator0,47 (0,37-0,57)0,46 (0,38-0,55)0,690 (0,598-0,800)0,705 (0,607-0,800)
Macrophyte indicator37,3 (33,9-40,4)37,5 (33,1-41,1)0,425 (0,292-0,562)0,449 (0,305-0,584)
Macrofaunal indicator0,654 (0,504-0,794)0,636 (0,466-0,787)
Fish indicator0,593 (0,399-0,717)0,564 (0,375-0,739)0,61 (0,44-0,74)0,59 (0,45-0,73)
Table 1: Medians and quartile range (25-27 perc.) of river and lake water quality indicator values between planning cycles 2010-2015 and 2016-2021 (based on GIOŚ data); red font indicates the only indicator that showed a statistically significant difference between cycles; the macrofaunal indicator for lakes has been implemented in water monitoring since 2017.

Of course, this is the magic of statistics and a big simplification, because at the level of individual objects in the analyzed period the condition may have worsened or improved, but in general “everything is as it was, nothing has changed.” Either the corrective actions are ineffective, poorly chosen, or simply lacking. As reported in numerous reports and scientific literature, very often the measures in place to implement measures to prevent deterioration of water quality are not linked to identified pressures, or such a link is poorly documented [6].

All to blame for the deviations?

A significant obstacle to achieving the WFD’s goals may be the overuse of the exemptions contained in Art. 4 of the directive, as they allow member states to lower the ambition of the directive and delay the achievement of good status, thereby undermining the very idea of the directive. Critical voices point to an excessive number of water bodies that are subject to insufficiently justified derogations. An analysis of 120 policy documents and 15 structured surveys shows that differing viewpoints and interpretations of deviations from environmental goals were already in place at the stage of negotiating the directive’s provisions, and leaving them undefined was intentional [7].

In addition, dysfunctional decision-making procedures in the joint implementation strategy and lack of adequate political support have made WFD implementation a major challenge that many countries have not fully overcome. As a result, pragmatism has been the deciding factor in many cases involving failure to achieve good water status, and the number of derogations applied in all countries is increasing [7]. In this aspect, too, we can speak of a clear loss of momentum – it was supposed to be ambitious, and it came out as it did.

Many authors point to the lack of sufficient economic instruments and management methods, and the need to harmonize approaches to deviating from environmental goals, including better use of cost-benefit analysis, affordability analysis, consideration of non-financial benefits (not just those limited to water aspects), the need to increase participation by local authorities and all stakeholders, assessing the uncertainty of environmental goals and the effectiveness of actions in the face of changing conditions, among others. climate change [8]. All of this indicates that it is necessary to critically evaluate and revise economic concepts and their tools for effectiveness in achieving goals.

Unrealistic timeframe of the directive

Or is it simply that aquatic ecosystems need more time to recover, and we expect too rapid an improvement? Let’s drop a veil of silence on the canonical 2015 deadline for achieving good status for all EU waters, which should have seemed overly optimistic even to the biggest enthusiasts. Regeneration of a degraded aquatic ecosystem in 15 years? Jokes aside. In 2015, nearly half of Europe’s surface waters failed to reach good ecological status, and the chemical status of 40 percent of them was unknown.

The next time horizons, indicated in the directive as the limit for achieving good water status, indicate 2021 (already behind us), followed by the absolute final one – 2027. This is achievable provided we experience a miracle within four years. Taking into account the complexity of ecological and sociological conditions, such as the timing of the full life cycles of organisms, the change in humanity’s mindset, the non-renewability of some environmental resources and the timing of the renewability of others, a realistic period for achieving environmental goals according to the scientific community is about 100 years [9].

Is there anything else we can do?

For the development of effective water management strategies and tools, it is crucial to identify the natural and anthropogenic factors that determine biotic changes. Haase’s team also analyzed such factors in their work and demonstrated climate, river partitions and the proportion of urbanized and agriculturally used areas upstream as the main determinants of trends in taxonomic and functional indicators representing freshwater invertebrate communities in Europe. Such results are probably no surprise to anyone.

It can be speculated that the slowdown in the rate of regeneration of aquatic ecosystems in the EU means the achievement of complete biological recovery, but in view of the generally poor ecological condition of waters in member countries, this thesis is incorrect. A more likely explanation is that the benefits of previous interventions have been exhausted, or new stressors are emerging or existing ones are intensifying (for example, new types of pollutants or the impact of a changing climate). Such factors can slow and potentially reverse biodiversity growth. This is supported in part by the results of Haase and co-authors, which show that increases in macroinvertebrate abundance and diversity were smaller and less frequently observed in rivers located in regions with warmer climates, draining from urban and agricultural areas and downstream of dams.

Assuming that the wellness of Europe’s rivers has stalled, the obvious question is how to restore the regeneration process. The challenges facing freshwater ecosystems are manifold, and the necessary interventions require a multifaceted approach that will include, among other things, the development of appropriate legislation, technological developments (for example, in wastewater treatment), changes in land use practices, or reductions in water exploitation. Further work to understand the causes of the slowdown in renewal would help guide these efforts.

Despite the disappointment resulting from less-than-expected results, we absolutely should not stop our efforts to improve water quality. By taking appropriate action following the ratification of the Montreal Protocol in 1987. has largely succeeded in reducing ozone depletion and bringing this indicator to a value not exceeding safe planetary limits [10] (we wrote about planetary limits in the autumn issue of Water Matters). So something can be done after all!

Climate change works against us – rising temperatures increase evaporation, promote eutrophication, and increase the risk of harmful algal blooms (HABs). This may mean that the environmental targets (parameter limits defining good water status) developed 20 years ago may not be sufficient to prevent ecosystem degradation. The question is whether we will go into derogations and lowering of environmental targets, risking the very likely complete collapse of Europe’s waters, or rather take up the challenge of saving what we can!


In the article, I used, among others. From the works:

  1. Haase P., Bowler D.E., Baker N.J. et al. (2023). The recovery of European freshwater biodiversity has come to a halt. Nature, 620, 582-588. https://doi.org/10.1038/s41586-023-06400-1
  2. Hesthagen T., Fjellheim A., Schartau A.K. et al. (2011). Chemical and biological recovery of Lake Saudlandsvatn, a formerly highly acidified lake in southmost Norway, in response to decreased acid deposition. Science of the Total Environment, 409, 15, 2908-2916. https://doi.org/10.1016/j.scitotenv.2011.04.026
  3. Hilt S., Alirangues Nuñez M.M., Bakker E.S., et al. (2018). Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes. Front. Plant Sci. 9:194. doi: 10.3389/fpls.2018.00194
  4. Hering D., Borja A., Carstensen J. et al. (2010). The European Water Framework Directive at the age of 10: A critical review of the achievements with recommendations for the future. Science Of The Total Environment, 408, 19, 4007-4019. https://doi.org/10.1016/j.scitotenv.2010.05.031
  5. Birk S., Bonne W., Borja A. et al. (2012). Three hundred ways to assess Europe’s surface waters: An almost complete overview of biological methods to implement the Water Framework Directive. Ecological Indicators, 18, 31-41, https://doi.org/10.1016/j.ecolind.2011.10.009
  6. Voulvoulis N., Arpon K. D., Giakoumis T. (2017). The EU Water Framework Directive: From great expectations to problems with implementation. Science of the Total Environment 575 (2017) 358-366. https://doi.org/10.1016/j.scitotenv.2016.09.228
  7. Boeuf B., Fritsch O., Martin-Ortega J. (2016). Undermining European Environmental Policy Goals? The EU Water Framework Directive and the Politics of Exemptions. Water, 8, 388. https://doi.org/10.3390/w8090388
  8. Berbel J., Expósito A. (2017). Economic challenges for the EU Water Framework Directive reform and implementation. European Planning Studies, 1-15. DOI: 10.1080/09654313.2017.1364353
  9. Josefsson H. (2012). Achieving ecological goals. Laws, 1(1), 39-63. https://doi.org/10.3390/laws1010039
  10. Richardson K., Steffen W., Lucht W. et al. (2023). Earth beyond six of nine planetary boundaries. Sci. Adv. 9, eadh2458. DOI: 10.1126/sciadv.adh2458

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