Nanoparticles and microplastics - real threats or toxicological fashions

Lauantai 13.1.2024 klo 19.21 - Mikko Nikinmaa

In the beginning of 2000s nanotoxicology became very popular. Before 2004 there were no Web of Science articles, in the 5-year period 2004-2009 175, 2010-2014 slightly above 1000 and between 2015 and 2019 about 2100. The results clearly showed that nanomaterials can be toxic. However, virtually all studies were done with nanomaterial levels which far exceeded environmentally relevant levels. Once it was established that nanoparticles can be toxic, it has become clear that their effects in nature must be demonstrated before they can be considered to be an ecotoxicological problem. Luckily it appears not to be the case as the number of nanotoxicological studies has decreased markedly, to about 900, in the last five years.

One can naturally hope that all the studies which demonstrated the possibility of toxic effects were enough to alert the people responsible for the disposal of nanomaterials about the need to consider how the waste is treated. If that were the case, toxicological research had reached a major goal: preventing a potentially significant environmental problem from developing. In worse case, the situation shows that a lot of scientists eagerly follow the fashion and study something that is popular without considering its importance. What the results have shown is that nanoparticles are probably entering the cells of organisms via, e.g., pinocytotic pathways. Thereafter the effects are probably due to the toxicity of the compound(s) which the particle is made of, and environmental impact depends on the probability of nanoparticle concentration reaching a level which causes malfunction of some organisms.

Thus, nanoparticle toxicity is really the toxicity of the material that the particle is made of, the particle itself is only a means of entering the cells. For example, charged compounds are virtually impermeant, but if they are nanoparticle components, they can be taken up via pinocytosis. If the charged compound thus entering the cell is toxic, it will be harmful. So instead of nanotoxicology addressing all nanomaterials, we should evaluate, which toxic materials are used in nanoparticle formulation. If a material is inert, toxic effects are not likely.

About five years after nanotoxicology became in fashion, the same happened to microplastics. Between 2011 and 2015 there were merely 290 studies about them, but during the past five years close to 14000. Most of the studies are concerned with the distribution and uptake of the microplastics. They have now been found everywhere, from Antarctica to glaciers in the Alps and within virtually all organisms, mothers’ milk etc. Their occurrence everywhere is quite clear, but actually very little is known about their toxicity. In contrast, plastic waste, macroplastics has various harmful effects in addition to fouling the environment. Animals get stuck to plastic waste, plastics can clog their lungs, gills or intestine. To everyone watching news reels the sorry sights of seals and birds having died in nets is familiar. But microplastics, their effects are uncertain.  

If microplastics are made of pure polyethene or polyethylene, I have difficult to see that they could be toxic. They are inert materials which can, in my opinion, best be compared to cellulose or starch, which we and all the herbivores eat and digest all the time. However, as with nanoparticles, microplastics can be toxic, if they are associated with toxic materials. This is possible or even probable, if the environment is polluted with hydrophobic toxicants. They get adsorbed to plastics instead of any aqueous material. The toxic particles can then be taken up via pinocytosis and exert cellular toxicity. However, again as with nanoparticles, microplastics in themselves are not toxics, they are just the means by which hydrophobic toxicants can get in the tissues.

As a conclusion, I must stay that many of the studies on nanoparticles and microplastics have been done because the topics are fashionable. Instead of showing over and over again that nanoparticles can be toxic or that microplastics are found everywhere one should start considering, when their presence causes environmental risk because of their association with the pollutants which are the true problem.

Where have the eels gone

Keskiviikko 18.1.2023 klo 14.51 - Mikko Nikinmaa

Everything was better in the past. That is the slogan of conservative populists throughout the world. It is actually true for some things, but the actions should be completely different from the ones advocated by the populists in order for us getting the good things from the past also in the future.

Here I am focussing on the eel. Smoked eel is a true delicacy. When I was a child, one got eels virtually every time one went fishing. The fish was fatty and had virtually no bones making it tasty and easy to eat. However, eels started disappearing from the shops and waters from 1970’s onwards and now you can rarely find them anywhere.

The life cycle of the eel is the main reason why the species is so vulnerable to environmental contamination. The European eel stocks have decreased more than 90 % from 1970’s to 2010’s. If one starts from the sexually mature eel, it migrates several thousand kilometres from the inland waters, where it matures, to the spawning site in Sargasso Sea. During this months-long migration the fish does not eat, but uses the fat deposits as energy stores. This fact has several consequences. First, the condition of eels reaching the spawning site is poor. Many do not make it to the site at all, and the rest are barely able to make the final effort of the spawning migration. Any lipid-soluble environmental contaminants are released to the circulation when lipid deposits are used for energy production. This further weakens the fish. Also, because of the climate change, the ocean currents may have weakened causing an increase in the energy consumption during swimming from Europe to Sargasso Sea. This also weakens the eel before spawning.

The adult eels die after spawning, but the developed embryos start their long travel towards the European feeding grounds. No specific problems have been found in the early part of the migration in the Atlantic. However, it is possible that the food items of the eel embryos have decreased in abundance and that ocean currents have slowed down. When the eels come to the European coasts, a final strenuous part of the travel awaits. They must go up to suitable growth sites. In selecting where to swim to, eels use, e.g., the lateral line organ. This sensory organ is very sensitive to metal contamination. Thus, the present increases of copper, lead and cadmium levels may disturb the final leg of eel migration.

In short, eels suffer from environmental contamination in most parts of their migration. Further, the studies have shown that the presently occurring contaminant levels are adequate to cause, e.g., sensory problems. Consequently, to be able to go back to the good old days, when smoked eel was a common delicacy, we need to improve water quality.

Decreased oil use influences climate change in two ways

Keskiviikko 8.6.2022 klo 20.22 - Mikko Nikinmaa

Oil spills are among the biggest toxicological problems in marine environments. Although the news pictures invariably show oil-covered birds, which die of heat loss in water, oil components are also very toxic to all aquatic organisms. The decrease in the use of fossil fuels will decrease the tanker transport of oil, oil leaks in the harbours of oil refineries, and accidental or intentional oil spills from ships. The net result is that oil pollution will diminish. Although only the importance of oil burning is usually considered as being important in combatting climate change, the decrease in oil pollution must also be considered. The fact is that marine algae carry out about half of the carbon dioxide removal and oxygen production by photosynthesis. Algal photosynthesis has decreased by 10-20 % because of marine pollution. This decrease is so far greater than what has been caused by deforestation of rainforests. The main pollutant causing algal deaths is oil and its components. Thus, decreasing the oil use will combat climate change not only directly but also as decreased oil pollution enables algal photosynthesis to recover. As a consequence, oil ban will have greater positive effect on climate than expected from decreased carbon dioxide production because of oil burning.

Environmental Pollution Accentuates Problems of Hypoxic Fish: Why?

Maanantai 20.9.2021 klo 14.55 - Mikko Nikinmaa

Hypoxia, i.e., low oxygen concentration, has increased in aquatic environments throughout the world. Hypoxia is mainly caused by eutrophication of waters whereby the oxygen consumption of organisms (but also oxidation of dead materials) increases. The occurrence of hypoxia is either continuous or diurnal. Diurnal changes in oxygen levels occur, if the eutrophication is mainly resulting from the increased biomass of photosynthetising organisms: during the day, when light is available, the increased photosynthesis can cause the environment to become hyperoxic, while at night even those organisms only respire, whereby the oxygen level drops. Continuous hypoxia occurs, when the oxygen demand always exceeds its diffusion (especially from the air) and production.

Fish take up the oxygen they need via the gills. The gills are also the major site of acid-base and ion regulation. This dual function has generated the “osmorespiratory compromise”:   high functional surface area and low diffusion distance favour oxygen uptake, whereas low functional surface area and high diffusion distance favour ion regulation. Aspects of this have been reviewed by Wood and Eom in Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology 2021 Vol. 254 (DOI: 10.1016/j.cbpa.2021.110895). From the environmental pollution point of view, it is important to note that many if not most pollutants have important effects on gills.

Because of the effects of pollutants on gills, it can be expected that the hypoxia responses of fish are affected by pollutants. This is all the more worrisome, as the same sources are the cause of both eutrophicating nutrients and many toxic wastes, i.e., water that has gone through wastewater treatment plants. Lau et al. have studied, how hypoxia responses of fish vary in clean water and in effluent from a modern wastewater treatment plant (Lau et al. Environmental Pollution 2021 Vol. 284, DOI: 10.1016/j.envpol.2021.117373). They observed that the hypoxia tolerance of fish was markedly decreased. This was associated with a reduction in the decrease of the so called intralamellar cell mass. Recently, it has been found that fish increase the functional area of gills in hypoxia largely by decreasing the intralamellar cell mass. If this cannot be done, hypoxia tolerance is impaired. It is not known, why the intralamellar cell mass could not be reduced in the effluent-treated fish. However, the results clearly show that the osmorespiratory compromise of the gills is an important factor to be taken into account when the success of fish in polluted, hypoxic environments is studied.

Disruption of rhythms - a significant toxicant effect

Tiistai 20.4.2021 klo 17.25 - Mikko Nikinmaa

Virtually all animal functions are rhythmical. If you measure a parameter, the value is different in the morning than in the evening or in the summer and in the winter. Despite this fact, the rhythmicity is seldom taken into account in considering the effects of toxicants on animals. We have earlier published an article indicating the importa

nce of disturbed rhythms in environmental responses (Prokkola and Nikinmaa Journal of Experimental Biology, 2018, 221, jeb179267). Now in Environment International (149,  106159, 2021) Zheng et al reviewed how “Environmental chemicals affect circadian rhythms: An underexplored effect influencing health and fitness in animals and humans.”

Zheng et al showed how tens of environmental toxicants including pesticides, steroids and metals can be considered circadian disrupters. Thus, the toxicants cause disturbances if normal rhythms. Considering this, the responses to toxicants will disturb the daily and seasonal rhythms of animals. Since the rhythms are an important 

aspect of animal fitness, the circadian disrupters will affect the success of animals. At the moment the rhythmical responses are further disturbed as the light-temperature relationship is altered by climate chang
e

Aquatic microplastics, not necessarily a problem

Tiistai 25.8.2020 klo 18.18 - Mikko Nikinmaa

Indigestible fibers are considered to be good for you. Such fibers enter your alimentary canal and pass through it without any changes, nothing is taken up in the gut. However, they help in the motility of the gut, and some materials, which are indigestible to us, can be utilized by gut microbes. Regardless, if material is going through your gut without anything taken up, it is inert and if its dimensions are such that it is easily transferred through the gut, cannot be considered harmful. The same is true for all animals.

So, fibers are good for you. If I changed the word fiber to microplastic, then people would start screaming about terrible poisons. Headline news almost everywhere in the world feature every once in a while stories about how these terrible microplastics are found in fish and other seafood, and can therefore be transferred to you. But if the dimensions are correct, the microplastics can be just like any other inert material going through the alimentary canal. Many plastics are nowadays made such that they meet foodstuff packaging requirements. If these plastics are broken down or if microbeads are produced from such plastics, they are completely harmless. We have been drinking water and soft drinks in plastic bottles for tens of years without being poisoned by microplastics, although every time we drink, we digest microplastics. So, in principle, microplastics are not a problem, if the material is foodstuff quality.

Microplastics can, however, be a problem. First, there are many types of plastics, some of which contain toxic components. Currently, about half of all the microplastics entering water are particles from tire wear. With the current traffic situation, there is very little one can do to this type of contamination. This is in contrast to microplastics in wastewater treatment plants, where more than 95 % of plastics are retained. The tire plastics have toxic components. Second, most of the toxic compounds are hydrophobic. Therefore, they adsorb on plastic particles, and will easily diffuse to organisms through the hydrophobic lipid gut walls. In this case it is not the microplastics themselves which are toxic, but the toxic compounds that have found their way to the environment. By stopping the release of these toxicants also the toxicity of microplastics would disappear.

The problem is that by focusing on microplastics in the aquatic environment, one is not addressing the real questions: decreasing road traffic (thus decreasing tire wear particles), decreasing toxicant release (thus decreasing toxicant adsorption and transfer into organisms) and completely stopping the use of toxic compounds in plastics.     

Functional changes are at the heart of encironmental biology

Maanantai 2.3.2020 klo 15.21 - Mikko Nikinmaa

Environmental changes and pollution will only have an ecological effect, if they affect the function of some organisms in the ecosystem. Consequently, any environmental effect must be primarily functional, i.e. physiological. Toxicology is studying functional disturbances.

On the basis of the above three lines, environmental (and also evolutionary) biology must be based on functional studies and explanations. In view of this, it is very inappropriate that environmental physiology remains a minor discipline in environmental biology and toxicology, and evolutionary biology as compared to ecology and genetics. My ecologist and geneticist friends always disagree with this, and give the following arguments. The ecologist says that many of the effects are indirect, which thus shows that only ecological studies can explain the effects. However, the effect may be indirect to the species (or group) one is studying, but there must be a functional effect on some organism in the ecosystem. If there weren’t, there would be no change. The geneticist and evolutionary biologist says that only the genetic changes will be transmitted to future generations. Thus, if an environmental change has an effect in the genome, that will be the important effect. While it is true that only genetically coded effect will be transmitted over many generations, a genetic change will only manifest itself if it affects the functions of organism in such a way that fitness (i.e. the number of offspring reaching sexual maturity) is affected. If the genetic change does not affect any functions, it is neutral both from the environmental and evolutionary viewpoint.

In fact, function (i.e. physiology) is what makes a difference between a stone and organism. A stone could have exactly the same molecules as an animal, but without functions (physiology) it would still be a stone.

Fashion largely determines what is studied in (aquatic) toxicology

Perjantai 18.10.2019 klo 17.37 - Mikko Nikinmaa

I finished as editor-in-chief of Aquatic Toxicology at the end of July after 14 years. During that time, I have handled more than 6000 manuscripts, which makes it possible to evaluate, what the scientists are studying. It also gives an indication about what is funded, since adequate funding is a prerequisite of being able to carry out the research. Overall, I must say that I am disappointed, since it appears that the funders mainly support fashionable topics, and scientists are naturally willing to do what gives them funding. Associated with this is the positive correlation between fashionable topic and the impact factors of journals. If you have many articles in a journal on a fashionable topic, its impact factor increases, even if the real environmental relevance of the work were poor. I present some major problems, which are the result of trying to do fashionable things instead of thinking already at the outset, what the real environmental relevance of the studies is.

First, it seems that using the newest possible methodology enables you to do work, which has little importance, and still get funded. In the past 15 years the -omics methods have increasingly been utilized by environmental toxicologists. Although they give new possibilities, if properly interpreted and utilized, their improper use is common, and many conclusions are faulty. Most studies use a very small number of organisms, typically 3. This is far too small number for any conclusions with natural populations of animals, especially as their environmental responses may involve changes in variability. I suppose everybody accepts that the responses to toxicants depend on the functions of proteins and their disturbances. Yet, most studies forget this, and based on real-time PCR, microarray or RNA-seq data, which show an increase in steady-state mRNA level conclude that the function encoded by the gene studied has increased. However, this need not be so: if the protein activity decreases because of the action of a toxicant, transcription is increased as a compensatory response. Yet, even after the compensatory response, protein activity may be reduced. In fact, some studies have seen this happening, but have not indicated this obvious explanation just being surprised of the finding. While the above concerns the commonly used transcriptomics, one can find problems with proteomics and metabolomics also. Basically, since toxicants can only affect organisms, if they disturb some functions, functional measurements are required. The -omics data help in finding the genes and consecutively functions, which may be affected. The reason why this is seldom done is twofold: functional measurements are time-consuming, and it is hard to make them high-throughput; the methodology is usually classical and does not attract funders as the use of fancy methodology does.

Second, nanotoxicology was in fashion a couple of years back. Between 2010 and 2015 one could publish virtually anything showing that nanomaterials can be toxic. In most cases, the amount of nanomaterial used has little bearing to what the environmental levels are or may be in future. Yet, relating the toxic actions to nanoparticles to their environmental occurrence is virtually undone. I fear that the same is happening with the new fashionable topic: microplastics. Horror stories are told about the effects of microplastics. Yet, virtually nothing is known about the effects of environmentally occurring levels of microplastics on the function of organisms.

Third, climate change and interactions of toxicants with temperature or oxygen level, or other environmental variables has hitherto been understudied. This knowledge gap is presently being filled. However, a significant problem remains, and most studies do not even indicate its existence. The studies are typically short, often 1-20 days, and the temperature, carbon dioxide or oxygen level change are typically imposed with virtually no lag time using values expected to occur a hundred years from now. This means that the stress levels in the studies are completely different from naturally occurring ones.

Finally, we are suffering from the tyranny of the mean. Virtually always a toxicological response is considered to be a change in the mean of a parameter. Changes in variance are virtually never considered as a toxicological endpoint. One is considering the heterogeneity of data only as determining if data transformation is needed for statistical testing. Yet, when I went over many toxicological studies, I observed that in most of them variability changed without a change in mean. In those cases, variability is undoubtedly a more sensitive indicator of a toxicological response than the mean. We have pointed out the possible importance of variability as a toxicological end point (Nikinmaa, M., Anttila, K. Individual variation in aquatic toxicology: not only unwanted noise. Aquatic Toxicology 207, 29-33; open access)

Aquatic Oil Pollution ? many-sided problem, until oil use is stopped

Torstai 18.7.2019 klo 11.44 - Mikko Nikinmaa

 

With oil spills, the usual picture in the news is a bird covered with oil. The contaminated bird loses its ability to regulate temperature in water and slowly dies because of heat loss. Although this is a significant problem during oil spills, it is probably not the most important one. As the most important one I would place the effect of oil contamination on mainly unicellular marine algae. Marine algae account for almost half of global photosynthesis, thus being the most important carbon dioxide sinks of the world. Largely because of oil pollution, it has been estimated that the algal carbon dioxide sink has decreased by 20 %. This negative effect is greater than would be caused, if deforestation of Amazon rain forest would increase manyfold. Oil pollution also influences fish. Effects are largely age-dependent and associated mainly with cardiac function. It appears that the toxicity of oil increases with increasing pressure. This is significant, as oil is drilled at deeper depths than earlier. In addition, dispersants, changing oil to small droplets, which are dispersed in the water column, increase the toxicity of oil spill to fish and other aquatic organisms, mostly by increasing the surface area of oil in contact with the (respiratory) surface of organisms. As a consequence, the uptake of toxic components of oil, and thereby their toxic effects, are increased. In contrast, the dispersants in the concentrations used appear to cause little toxicity. It is quite clear that as long as oil is used in significant amounts in fuels and energy production, the problems persist. Further, the socalled biofuels or biodiesels are exactly as bad for aquatic life as fossil oil. Therefore, in terms of combatting climate change, using biofuel is exactly the same as using fossil oil, if the use of fossil fuel is coupled with forestation.

Changes in Individual Variability - an Important Component of Environmental Rsponses

Perjantai 31.5.2019 klo 16.35 - Mikko Nikinmaa

Sexual reproduction maximizes the variability of offspring to parents. Variability is the basis for natural selection and consecutively evolution. These statements are generally accepted. In view of this, it is amazing that individual variability is relegated to noise or error in much of experimental biology: we talk about “standard error of the mean” and “confidence interval”. However, the error component, which relates to inaccuracies in measurements represents only a small percentage of variation in biological measurements.

Variability is actually tested in most articles, but not because it is thought to be important in itself. The homogeneity of variance is tested in order to evaluate, if parametric statistical testing of the mean can be done, if data transformation (e.g. logarithmic transformation) must be done before parametric testing is possible or if one must resort to non-parametric statistical testing. When reading toxicological and physiological articles, one started to get the feeling that many if not most of them showed that data were heterogeneous. Therefore, we (Nikinmaa and Anttila, Aquatic Toxicology 207, 29-33;2019) went through a whole host of recent articles and found that more than 80 % of the ones which reported homogeneity/heterogeneity of data found heterogeneity. Thus, the original gut feeling that the different experimental groups had different variances, appeared correct.

The change in variability is important in identifying an occurrence of an environmental response, if it can occur without a change in the mean value measured after the treatment. Again, looking at the published literature, this seemed to be the case: in many if not most studies, a change in variability occurred even when no change in the mean value occurred. To ascertain that this was not only appearance, we tested if variance could change without a change in the mean using the water-soluble fraction (WSF) of crude oil and measured the oxygen consumption rate of Daphnia. The results unequivocally showed that WSF decreased the variability of oxygen consumption rate without affecting its mean value (Nikinmaa et al., Aquatic Toxicology 211, 137-140; 2019). Thus, a change in individual variance can signify an environmental response. Presently, it is not known, to what extent this occurs, since experimental designs have not explored this possibility.

There can be many different reasons for individual variability. One is that the studied animals usually present various genotypes, which may respond differently. This is, undoubtedly, an important component in generating variability. However, differences between individual Daphnia occur even though the animals are genetically identical. Actually, large non-genetic variation can have significant beneficial survival value for an organism, if the environment has cyclical changes with each portion of the cycle lasting for some generations: for example, if large variability with regard to temperature tolerance is achieved via the population consisting of several genotypes, each having small variation in tolerated temperature, an increase in temperature will wipe out all the other genotypes except the ones tolerating high temperatures. If the temperature then decreases, the high temperature-tolerant genotype cannot survive. If, on the other hand, the wide temperature tolerance is non-genetic, acclimation to high temperature will not affect the low-temperature tolerance, and some individual will survive the low temperatures.  In natural populations it must also always be remembered that the exposures and environmental conditions by different individuals are not truly identical, whereby, e.g., life-time toxicant exposure can vary.

As a conclusion, it is quite clear that changes in individual variability can constitute an important component of environmental responses. It could be very valuable for environmental biology, if scientists re-explored their datasets concentrating on changes in variability instead of the mean. This would give us information about the role of changes in variability in environmental responses very rapidly.

 

SETAC (Society for Environmental Toxicology and Chemistry) in Helsinki 26.-31.5.

Sunnuntai 26.5.2019 klo 13.26 - Mikko Nikinmaa

This coming week more that 2000 environmental scientists meet in Helsinki discussing many different aspects of environmental contamination, starting from indoor air quality ang going to endocrine disruption in wildlife. Presentations include those on nanotoxicology, plastic pollution and climate change. Thus, pressing environmental problems are handled by a wide internationel group of experts. My personal input in the meeting is a session on individual variation in toxicological responses, which I wll discuss here later.

Toxicity of Nanoparticles - Hype or Reality

Sunnuntai 8.4.2018 klo 12.27 - Mikko Nikinmaa

During the recent past, the toxicity of nanoparticles (i.e. particles with at least one dimension less than 100 nm) has become a very fashionable field of toxicological studies. There is now ample evidence that the particles can be toxic, if their concentration is high enough. And that is the major problem of most nanotoxicological studies: the nanoparticle levels are often thousands of times higher than what can be expected to occur in the environment. Since one has now clearly shown that nanomaterial can be toxic, it would be high time to study the possible environmental relevance of the toxicity. If there is none, then the studies showing toxicity are irrelevant. This is because one can find toxic amount of any substance. For example, one can demonstrate a lethal dose for water. As Paracelsus said already in 16th century: All substances can be poisonous, the dose makes the difference between remedy and poison.

A significant problem with nanomaterial studies is that the methodology used is suitable especially for dissolved substances in aquatic media, but is not necessarily suitable for the new material. Hitherto, methods, which would be specific and good for nanomaterial research have not been developed. A significant property of nanomaterials is their tendency to aggregate, and the influence of this on the toxic properties is poorly described - it makes definitely a big difference if aggregation occurs before the contact with organisms or only after cellular uptake. One toxic effect of nanomaterials, which is independent of their metal components, is that they cause oxidative stress (and inflammation). This property may get worse with aggregation - we do not know. As the worst possible scenery one can think that nanomaterials cause similar problems in airways as asbestos: this may be fearmongering, but until environmentally relevant nanotoxicology studies are available, the possibility cannot be discounted.

Physiology - the centre of environmental research

Lauantai 6.5.2017 klo 15.43 - Mikko Nikinmaa

As I am again reading a grant application on conservation biology, I started thinking what is important when combining environmental changes and organisms. And the single factor is physiology (=function). This conclusion may be surprising, as physiology is virtually always at least in Finland considered to be a minor field of biology with little importance in environmental science. However, I hope that the points I make below will convince the reader about the truth of the conclusion.

First, without functions organisms would be just stones. They could  have exactly the same molecules, including the whole genome, but if they would not function (=be physiologically active), they would be just unliving material with interesting molecules.

Second, environmental changes will influence the ecosystem only if the function of some organism(s) in the ecosystem is affected. Thus, any ecological effects are only seen after  there must be physiological effects. It is possible that one does not see any change in, e.g., species abundances or composition, even if the environmental disturbance is affecting the physiology of organisms, provided that immigration/emigration balances the disturbance. Consequently, environmental changes can be observed first at the physiological level; physiological changes may cause measurable ecological effects.

Third, even if environmental changes affect the genetic makeup of organisms, the changes are only important, if the physiology of the organism is affected in such a way that the fitness of organism (taken as the number of sexually mature offspring produced) is influenced. Thus, also genetic effects of environmental changes are only seen, if changes in the physiology of organisms take place.

As a conclusion, physiology should be in the centre of biological environmental research. This has already been realized in some cases in USA: I recently participated in filling a position of conservation biology, where a physiologist was selected instead of other biologists. I hope that in this regard Finnish science would be among front runners in noting how environmental biology should develop.