From Acid Rain to Ocean Acidification

Keskiviikko 11.9.2019 klo 18:42 - Mikko Nikinmaa

In 1980’s the environmental problem in the news in Europe was acid rain. The sulphur dioxide (and to smaller extent oxides of nitrogen) emitted in the smoke from coal burning, condensed in clouds, and was part of the rain entering Scandinavian poorly buffered lakes. The pH of the lakes could decrease from 7 to 4 and wipe out virtually all the fish, shellfish and crayfish of the lakes. The toxicity of acid rain was aggravated by aluminium (Al). Aluminium is insoluble at high pH values, but acid rain solubilized it. The free metal ion, predominant at pH-values below 5 is highly toxic, and kills fish and crustaceans by disturbing their ion regulation. At higher pH values the aluminium hydroxides precipitate on the gills of aquatic animals causing their death. As a result of acid rain, the lakes had clear water, but virtually no animal life. At that time aluminium was considered to be a very bad toxicant. Having studied the acid rain-aluminium toxicity, it is difficult for me to understand that presently aluminium sulphate is used to “restore” lakes. Toxic aluminium will kill fish and invertebrates also in this case. Naturally, if the purpose is to get clear water, that is the thing to do, but as the acid lakes justify, clear water does not mean water, where animals can live.

In comparison to freshwater acidification, where water pH could decrease up to 3 pH-units, the most likely pH-decrease in ocean acidification is 0.3-0.4 units by 2100. Asranta.jpg a pH change this would not be a problem for animals, if it were not the result of changes in the carbon dioxide-bicarbonate-carbonate equilibria. In 1970’s and 1980’s the acid-base regulation of animals was studied extensively, using, e.g., hypercapnia (increased carbon dioxide level) as a disturbance. It was found that fish and other aquatic animals are quite poor in handling external carbon dioxide loads. While the degrees of hypercapnia used were much higher than the environmentally relevant ones during ocean acidification, it seems quite clear that any disturbances observed in animals are due to hypercapnia. The reasons for this are at least the following: (1) Aquatic animals have low total carbon dioxide levels. Consequently, any increase in external carbon dioxide tension, as happens during ocean acidification, will decrease the efficiency of carbon dioxide excretion. Since carbon dioxide is the major end product of aerobic energy metabolism, this causes disturbances of energy metabolism. (2) Increased carbon dioxide level can only be achieved at the expense of carbonate levels, which must decrease. All the shells of invertebrates are made of calcium carbonate. Thus, shell formation may be disturbed by ocean acidification. So, it is really the problems of handling carbon dioxide, i.e. hypercapnia, and not the pH-changes, that are the questions in ocean acidification.

Kommentoi kirjoitusta. Avainsanat: carbon dioxide, pH, climate change, aluminium

Individual variability is the key for tolerating environmental change

Tiistai 25.12.2018 klo 13:10 - Mikko Nikinmaa

When animal (or plant) populations must face environmental change such as increased themperature, eutrophication etc. the greater the variability bIMG_20170803_0035_NEW.jpgetween organisms, the more likely it is that at least some specimens are able to tolerate the disturbed conditions. Hitherto it has been virtually always been thoght that the only important thing in this regard is genetic variability. However, individual variation is possible also without genetic variation: a single genotype can have quite different phenotypes, which tolerate different conditions. 

In the case that the environment is very labile such phenotypic plasticity - i.e. individual variations in physiological function of one genotype - is better way of tolerating unfavourable environment than having genetically heterogenous populatio with one genotype tolerating that environmental problem. This is because the plasticity of the individuals that tolerate the unfavourable environment is as large as that of the original population. If, however, the tolerance depends on the genotypic variation, it is likely that the overall plasticity of the tolerant genotype is smaller than that of the original, genetically variable population. Genetical variability can be of significant benefit only in cases where the change is to one direction. The possible importance of measures of individual variation in environmental response has recently been discussed in our article (Nikinmaa and Anttila, Aquatic Toxicology, 207, 29-33; open access). Our experimental results on oil-exposed water fleas also indicate that a change in individual variability can occur even when no change is seen in the mean of the measured parameter.

Kommentoi kirjoitusta. Avainsanat: climate change, environmental pollution, phenotypic plasticity

Circadian rhythms and environmental disturbances ? underexplored interactions

Perjantai 24.8.2018 klo 9:24 - Mikko Nikinmaa

Variation of functions with daily cycles is an important component of environmental responses of organisms, and environmental disturbances can affect daily rhythms. This possibility has been surprisingly little taken into account in environmental studies. For this reason Jenni Prokkola and I have written a commentary on the topic. Its abstract follows:

Biological rhythms control the life of virtually all organisms, impacting numerous aspects ranging from subcellular processes to behaviour. Many studies have shown that changes in abiotic environmental conditions can disturb or entrain circadian (∼24 h) rhythms. These expected changes are so large that they could impose risks to the long-term viability of populations. Climate change is a major global stressor affecting the fitness of animals, partially because it challenges the adaptive associations between endogenous clocks and temperature – consequently, one can posit that a large-scale natural experiment on the plasticity of rhythm–temperature interactions is underway. Further risks are posed by chemical pollution and the depletion of oxygen levels in aquatic
environments. Here, we focused our attention on fish, which are at
heightened risk of being affected by human influence and are
adapted to diverse environments showing predictable changes in
light conditions, oxygen saturation and temperature. The examined
literature to date suggests an abundance of mechanisms that can
lead to interactions between responses to hypoxia, pollutants or
pathogens and regulation of endogenous rhythms, but also reveals
gaps in our understanding of the plasticity of endogenous rhythms in fish and in how these interactions may be disturbed by human
influence and affect natural populations. Here, we summarize
research on the molecular mechanisms behind environment–clock
interactions as they relate to oxygen variability, temperature and
responses to pollutants, and propose ways to address these
interactions more conclusively in future studies. (Source: Prokkola JM, Nikinmaa M, Journal of Experimental Biology 221, jeb179267)

Kommentoi kirjoitusta. Avainsanat: Photoperiod, Climate change, Xenobiotic

Disinfectants in house cleaning and personal care products - not needed and an environmental hazard

Sunnuntai 2.7.2017 klo 18:06 - Mikko Nikinmaa

Disinfectants are extensively used both in cleaning and personal care. They kill unselectively bacteria and molds. A major compound in disinfectants is triclosan, which can nowadays be found in most water bodies in the world. Since it is a very common contaminant of waters, there have been approximately 50 studies about its toxicity to various organisms published in Aquatic Toxicology in 2010's. Apart from being toxic to the target organisms - bacteria, cyanobacteria and other biofilm components including unicellular algae, triclosan is toxic to non-target organisms such as mussels, crustaceans, fish and frogs. What makes the compound worrysome as a pollutant is that effects on non-target species are reported in environmentally realistic concentrations. While all the mechanisms of action of triclosan are not known, at least development in fish and frogs is affected. The compound affects thyroid hormone pathway, which is known to be involved in the development and metamorphosis of frogs.

Since disinfectants are not really needed - healthy communities of micro-organisms are causing no harm - and since environmentally realistic concentrations of triclosan already cause toxic effects, the use  of the compound should be minimized. The benefits are hardly great enough to justify the hazards.

Kommentoi kirjoitusta. Avainsanat: water pollution, pharmaceuticals and personal care products, triclosan

Kaliningrad waste water treatment plant: ready at last

Sunnuntai 18.6.2017 klo 11:38

Kaliningrad area in the coast of Baltic Sea has been without waste water cleaning until about a week ago (June 2017). The waste of about a million people has been led to the Baltic Sea untreated. Among the present point sources of polluting, especially eutrophicating wastes, the area has recently become the most significant in the Baltic area. (After St. Petersburg waste water treating plants have started full function). Kaliningrad WWTP has been planned and built for the past 40 years, so after it was finally functioning, one can with good reason give a suck of relief.  

Kommentoi kirjoitusta. Avainsanat: Baltic Sea, eutrophication, water pollution

An Important Book on Baltic Sea

Tiistai 18.4.2017 klo 15:50 - Mikko Nikinmaa

Just recently Springer published Biological Oceanography of the Baltic Sea., edited by Pauline Snoeijs-Leijonmalm, Hendrik Schubert and Teresa Radziejewska. So if you are interested in what makes the Baltic to what it is, including what presently contaminates it, the book is worth reading. With 686 pages, and a list of prominent scientists as writers of its different chapters, it is the most authoritave work of the biology of the Baltic Sea published in many decades.

Kommentoi kirjoitusta. Avainsanat: oceanography, pollution, eutrophication