Water through the eyes of a hydrobiologist

I will begin my column about water in the eyes of a hydrobiologist with a very unprofessional statement: of all the sciences with water at their center, hydrobiology is perhaps the most glamorous. Of course, science is completely not about glamour, but nevertheless what most of us, professionals as well as laymen, find most captivating about aquatic and water-dependent ecosystems is their plant cover and the animals that inhabit them. Who among us, spending time at the lake, at least once did not marvel at a patch of flowering water lilies or the impressive wings of the great sailfish? Who wasn’t impressed by the sight of a rush shrouded in morning mist or (if they were lucky) a diving kingfisher? My professional path was determined, I think, by my fascination with the floating islands of peat moss on a dystrophic lake and the unique atmosphere of mystery that prevails in peat bogs. In college, I chose to specialize as a hydrobiologist.

Hydrobiology is the science of organisms that live in aquatic environments. It can apply to marine waters, overlying areas of the seas and oceans, or inland waters, filling continental basins. As Professor Plinski writes in his Fundamentals of Hydrobiology, it is anachronistic and inappropriate to call the latter fresh waters, as it is known not at all uncommon for continental waters to be significantly more saline than ocean waters (and this is not always due to degrading human activities). Within inland waters, on the other hand, hydrobiology can refer to standing or flowing waters, as well as spring areas and a whole range of different types of wetlands. The water seemingly the same, yet the ecosystems in terms of environmental factors, taxonomic structure and functioning are completely different.

Hydrobiology, like all other sciences, has its narrower divisions. The basic and also most intuitive division follows the line of kingdoms and includes hydrozoology and hydrobotany, as well as the less intuitive hydromycology (the science of fungi found in water). The Protista kingdom does not seem to have lived to see a separate division, and organisms classified in this taxonomic group are usually part of the study of the previous three divisions. Of course, these divisions go much deeper and can include rather narrow specialties involving groups of organisms at different taxonomic levels, such as algae (phycology, also known as algology), fish (ichthyology), dragonflies (odonatology), crustaceans (carcinology), mollusks (malacology) and many others.

Hydrobiology, as a rule, includes an ecological context, that is, it refers to the relationship of organisms to the ecosystem. A specialist in this field studies and describes the relationships and interrelationships between organisms and the various environmental factors that these organisms inhabit. So for me, water is first of all a habitat, a medium in which organisms with characteristics that enable them to carry out life functions in this specific environment live. I will say more, like any hydrobiologist, I am more interested in organisms (with a particular twist towards plants) than in water as such, although it is obvious that the characteristics of these organisms and their assemblages have been shaped by a whole range of factors of the environment in which they live. That is, what water, such organisms.

And it is the indicator traits of aquatic organisms, popularly known as bioindication, that fascinate me in particular. When I see a beautifully formed patch of lake lobelia community in the littoral, I know that the lake water is most likely characterized by low alkalinity, low concentration of mineral salts and probably a small amount of nutrients. Trichinella communities in the river will generally be indicative of significant flow, the presence of coarse material in the substrate and relatively good water quality, although the variability in habitat requirements among species of the Batrachium genus is high and not all are stenotopic. The significant water clarity in the lake (and in the conditions of the Polish lowlands it will be 3 – 4 m, at best above 5 m of Secchi disk visibility) tells me that the plankton density is low, and therefore the habitat is probably quite sparse. At that time, I expect a significant depth of submerged vegetation colonization of the littoral, as well as its specific taxonomic composition – brachiopod communities. On the other hand, dense thickets of calamus and broad-leaved clubmoss almost certainly indicate a high nutrient content, that is, a significant degree of habitat zeutrophication.

Although this knowledge, still incomplete and in need of exploration, has been available in numerous textbooks, guides and scientific publications for several decades (the first hydrobiology textbook by François-Alphonse Forel was published at the turn of the 20th century), it is nevertheless best acquired in the field. And it is field research that is the most attractive part of a hydrobiologist’s work. He doesn’t know the ecosystem who didn’t get dirty with mud up to his armpits, trudging through reeds, get wet and cold sampling in an early spring campaign, or get sunburned after several hours on a boat, swimming from transect to transect.

But in the era of the Anthropocene, the study of ecosystem ecology is not so much about recognizing the structure and function of natural systems (which are essentially gone), but rather about studying their response to anthropogenic pressures in the broadest sense. That is, the aforementioned bioindication in dynamic terms – assessing not so much the state, but changes due to disorders. When large amounts of allochthonous substances (usually anthropogenic pollutants) enter the water, my first question is how this will affect the remodeling of the set of organisms, what will survive in this water, what new organisms will find their niche here, and how such remodeling will change the circulation of matter and energy throughout the system. When, as a result of hydroelectric works, some rejoice in the improvement of hydrological parameters, I see, above all, the devastation of the habitat of millions of organisms and the complete degradation of trophic chains. Observing the many manifestations of human activity on the waters, I am amazed by the great carelessness in taking some, probably not always justified, actions. No one needs to be explained how the state of preservation of aquatic vegetation communities, as well as natural buffer zones, is affected by mowing vegetation from the bottom and banks or removing floating and rooting plants in the bottom. Or what the habitat of benthic invertebrates and fish looks like after the so-called de-silting work. Having worked for two decades at the intersection of science, administration and law, I am aware of the need for certain water management measures to meet the various needs of water users. However, this does not change the fact that it is difficult for us hydrobiologists to be indifferent to the environmental effects of such activities. All the more so because we are aware of their long-term effects and the associated disruption of entire ecosystems.

As anthropologist Malgorzata Kowalska rightly notes in her work published in 2022. in the pages of “Polish Ethnography,” the natural environment is best protected where people understand the processes taking place in it and feel responsible for them because of their awareness of their dependence on them. As Kowalska cites from Tim Ingold’s lecture “Sustainability of Everything”(2021), sustainable systems are those in which institutions provide the framework for conservation programs, but it is the local community that feels responsible for the environment to which it feels a sense of belonging. Thus, more effective conservation of nature requires not so much standards and regulations that allow for effective environmental management, but thinking about nature as a network of connections and relationships, of which humans are one element.

Knowledge of the determinants of biodiversity is crucial to understanding current issues such as ecosystem services, nature-based solutions and other environmental social challenges. Despite the long history of biodiversity research, there is still much work to be done to describe the patterns and understand the processes that lead to the creation and maintenance of biodiversity. For example, we are still far from identifying and naming all existing species. Even for those we consider well known, we cannot fully assess their population dynamics and range of occurrence. Moreover, we can only estimate the effects of their interactions in complex ecosystem systems and how small perturbations at the level of an individual, population or species can affect entire ecosystems. Awareness of the connections in the ecosystem therefore goes beyond the scope of strict ecology and should accompany all those who care about and depend on water quality.