Evolve or die?


Last June, I wrote a post titled “So what?”, which included a cartoon summarising all that I thought was wrong with the world of diatom specialists within which I move.   We have become, as a group, very good at naming and counting diatoms, but not very good at understanding how these fit into ecosystems.   Along with two colleagues, I included this cartoon in a paper that we wrote based on talks at the meeting that I wrote about in that post. One reviewer took umbrage at this, suggesting that “… it is really making a very bad favour to all the people working with diatoms, and to the efforts expended during many years to implement techniques related to them …” (sic).   Unfortunately, I feel that there is so much complacency amongst diatom specialists at present that we are hardly doing them a favour by writing platitudes. Inhabitants of the curious sub-discipline of diatom science seem to have drifted far from the frontline of functional ecology and some shock tactics are necessary in order to drag them back towards reality. We argued our case for including the cartoon and the editor agreed with us.

The roots of the problem are sociological and cultural rather than scientific: diatoms became established as the first choice algae for ecological assessment for a number of reasons, one of which was the absence of competition from advocates of other groups of organisms. Diatom methods behaved like an invasive species, spreading rapidly across Europe and beyond, exploiting the new “niche” created by the Water Framework Directive’s requirement that “phytobenthos” (i.e. attached algae) should be considered when Member States were evaluating the condition of their fresh waters.

What happened next was, I suspect, the natural consequence of academic specialisation. We all recognised that the first generation of methods were far from perfect but, as circumstances had selected diatom specialists (with their inclinations towards taxonomy) over those with interests in other algal groups and, more significantly, ecological processes, these people then dictated the next stages of development.   Over the past 15 years, I have watched the lists of species that analysts are expected to recognise gradually grow in length in many parts of Europe. Adherents of this approach claim greater sensitivity as a result, but there is little hard evidence to support this.   Rather, I think we are watching the natural inclination of specialists towards greater specialisation.

The line that we took in our new paper is that the “ecological status” that we are all trying to measure is a much broader concept than can be encapsulated by the composition of a single group of algae.   Importantly, it needs to consider not just what species are present but also how much biomass these create.   We recognise that measuring biomass is not an easy task but, paradoxically, diatom specialists in yet another recent paper point out that differentiating some groups of diatoms is difficult yet seem to think that this can be resolvable by greater diligence on the part of analysts, whilst every other facet of ecological status can be quietly ignored.

My inclination is to aim for much greater breadth of information in our assessments, accepting, at the same time, that this may entail less detail within the individual nuggets of information (see “The democratisation of stream ecology?”). There is, I recognise, a fine line between “streamlining” a method and “cutting corners” but it may be a price worth paying in pursuit of a wider goal. I explored this in a recent paper on redundancy in lake assessments (see “Unmasking the faceless Eurocrats …”), invoking the economic principle of “decreasing marginal utility”. Broadly speaking, the information content of any individual type of data decreases by a power law, such that the first 20% of effort (roughly) yields 80% of the answer.   The unique information content associated with the extra effort gradually tails off.   The question that no-one has satisfactorily answered is whether the “splitting” that now seems axiomatic amongst diatomists adequately balances the huge amount of information (on other algae, on biomass) that is completely ignored.

It seems straightforward if put in purely scientific terms, but the situation is complicated, again, by non-scientific, socio-cultural aspects. Specialist biologists, like all craftsmen/craftswomen, take pride in doing the best possible job. It is possible, too, that the extra data that they extract from a detailed analysis may turn out to be useful in the future, so why ignore it?   On the other hand, the creation of a cadre of specialist “diatomists” means that they see the “best possible job” exclusively in terms of their data and not in terms of the overall management of a river or lake. And finally, the widespread adoption of diatoms for assessment has created a niche for specialist contractors who work for environmental agencies and others performing the highly detailed analyses that are currently required. Any attempt to “streamline” the process threatens their livelihood.   So what starts as an impartial scientific debate is anything but, as the “Guild” of diatom analysts marshals its arguments.

Our paper forms the introduction to a series of papers arising from the Trento meeting. It may seem strange to open the proceedings with a fairly negative evaluation of the state of affairs, but I offer no apologies.   Pushing my ecosystem analogies just a little further, “specialist” organisms are vulnerable to changes in their habitat in a way that “generalists” are not.   The landscape of environmental regulation is not static and biologists, no less than the organisms they study, need to evolve in order to survive.


Kahlert, M., Ács, E., Almeida, S.F.P., Blanco, S., Dressler, M., Ector, L., Karjalainen, S.M., Liess, A., Mertens, A., van der Wal, J., Vilbaste, S. & Werner, P. (2016). Quality assurance of diatom counts in Europe: towards harmonized datasets. Hydrobiologia (in press) DOI: 10.1007/s10750-016-2651-8

Kelly, M.G., Schneider, S.C. & King. L. (2015).   Customs, habits and traditions: the role of non-scientific factors in the development of ecological assessment methods.   WIRES Water 2: 159-165.

Poikane, S., Kelly, M.G. & Cantonati, M. (2016). Benthic algal assessment of ecological status in European lakes and rivers: challenges and opportunities.   Science of the Total Environment (in press). (doi: 10.1016/j.scitotenv.2016.02.027) (The picture at the head of this post is the “Graphical Abstract” from that paper which is “open access”, thanks to the European Commission’s Joint Research Centre)


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