Fish in high-flow zone of rivers may be the first victims of climate change

Maanantai 25.9.2023 klo 18.56 - Mikko Nikinmaa

Fish living in high-flow areas of rivers have chosen (or evolved in) that habitat, because they need a lot of oxygen for their high activity. Flowing water becomes well oxygenated, as it is continuously exposed to air. However, the amount of oxygen taken up by water decreases with increasing temperature, simultaneously as poikilothermic fish need more of it, as temperature increase speeds up their metabolism.

If temperature increases enough, fish heart cannot pump enough oxygenated blood to sustain metabolism. This we have clearly shown in our article Anttila et al, Comp Physiol Biochem A 275, 111340 (2023). Although the study was done on seabass, the principle holds also for river fish. The amount of oxygen initially reaching the gills, where it is taken up, further decreases the maximal temperature the fish can tolerate.

Zhi et al (Nature Climate Change 2023;  https://doi.org/10.1038/s41558-023-01793-3) have shown that the oxygen level in rivers throughout Europe and United States has decreased for the past forty years. While increased temperature was the main driver, the oxygen level decreased more than expected because of temperature increase. It is possible that the general eutrophication with increased oxygen consumption.

Regardless, associated with the physiological response to increased temperature of fish, the temperature-caused decrease in maximal amount of oxygen the water holds, can cause extinction of salmonids living in the fast-flowing head streams.

Is seawater alkalinization an unproblematic way of carbon dioxide removal?

Maanantai 1.5.2023 klo 17.30 - Mikko Nikinmaa

It is simple. One just has ships floating in the high seas spreading alkaline substances to seawater. As a result, the pH of the seawater increases, carbon dioxide-bicarbonate-carbonate equilibrium is shifted to the right, and consequently carbon dioxide is mopped up. What a neat and cheap way of combatting climate change, and it can be done without any requirements for technological advancements. No wonder technology-oriented people have been jumping in excitement. But are there serious downsides?

The question becomes immediately relevant, as apart from the climate crisis we are experiencing biodiversity crisis. And any large-scale bioengineering project such as seawater alkalinization will affect the biota of the area which is alkalinized. It is not known how large the effects are, which species suffer from, and which don’t mind about the pH changes. So, if an alkalinization project is carried out, one is really doing a large-scale experiment with unknown results.

A recent modelling study about alkalinization of seawater and its possible effects has been reported in Environmental Research Letters (18: 044047; https://doi.org/10.1088/1748-9326/acc9d4; Fakhraee et al.).

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.

Physiological studies should be in the centre of climate change biology

Tiistai 12.4.2022 klo 15.49 - Mikko Nikinmaa

Climate change, and other environmental changes, affect the functions of organisms. The changes in populations and ecosystems follow these functional changes. If the functions of some organisms are not disturbed, the environmental change does not affect the ecosystem, if immigration and emigration can be accounted for.

These simple facts indicate that functional studies, i.e., physiology, should be in the centre of environmental biology. Indeed, a stone could have exactly the same molecules as an organism, but without functions it would still be a stone. However, physiological studies are marginalized in climate change research and environmental biology – there are less than 1/10^th of published physiological articles as compared to ecological articles within environmental biology. Furthermore, studies on animals account for less than 1/3^rd of the physiological studies.

In short, one carries out extensive ecological surveys and population genetic studies and observes that something has happened. This is the major problem with the research, it shows what has already occurred, but fails to evaluate why and how. With climate change research it is obvious that temperature increase plays a role, but only physiological studies can clarify, what the affected pathways are. Also, physiological investigations can answer in real time, if a disturbance is adequate to cause a perturbation in populations and ecosystems.

Climate change research as well as other environmental biology should be predictive. This requires that physiology becomes a central, not a marginal discipline. Studies require intensive, time-demanding work, which is often technically quite demanding. Because of this, the number of scientists working on physiological questions should be drastically increased. Only this makes it possible to turn environmental and climate change biology to predictive science, which is required to combat environmental problems.

Functions Determine Temperature Effects on Animals and Man

Torstai 30.9.2021 klo 19.05 - Mikko Nikinmaa

Climate change is one of the most studied topics of the present time. The web of science contains approximately 350 000 scientific articles studying the topic. Out of these, around 64 000 have studied the biology of climate change. However, only about 1500 of those appear to be concerned with animal or human physiology. This is very concerning, since any effects of temperature changes must be a result of physiological responses to the change. All the other findings on animals and man will be downstream consequences of the physiological adjustments. In view of the above, the recent compilation of reviews in the Journal of Experimental Biology is very welcome. Since it is open access, everyone can read it at https://journals.biologists.com/jeb/issue/224/Suppl_1.

As an example, polar bears have become iconic victims of climate change. There are several documentaries about skinny and diseased creatures about to succumb to increased temperatures as they find less food, when sea ice decreases because of an increase in temperature. However, if that were the only problem they are facing, their plight would probably be tolerable. But since their food availability is decreased, they need to spend an increased amount of energy to catch the prey. Because of the sea ice loss, the energy needed for locomotor activity is 3-4 times higher than expected. Another problem with endotherms is that an increase in temperature is less well tolerated than a decrease. Further, an increase in temperature is a serious problem in dry environments because water loss increases.

For ectothermic animals, temperature increase causes various problems. Dive durations of reptiles, turtles and amphibians decrease by about a third. This translates directly to decreased feeding efficiency. The thermal niches of fish become decoupled from the light-dark rhythms, which function as cues for reproduction etc. When thinking about thermal niches, it appears that both tropical and polar fish tolerate changes in temperature less well than temperate ones. Two overall problems are apparent in translating most temperature studies on fish to climate change scenarios. First, the temperature changes due to climate change are usually much slower than temperature changes imposed on fish in experiments. Second, individual variation as an important component of temperature responses of fish is hardly ever considered. Also, one knows very poorly, what the actual physiological mechanisms behind the measures of thermal tolerance are.

The major reasons why our understanding of physiological mechanisms behind the responses to climate change are poor is due to the fact that functional studies have not been considered important. However, any ecological or genetic response can only occur, if physiological changes take place earlier. Thus, predicting climate change effects on animal populations requires understanding how animals respond physiologically, not by observing changes that have already occurred (either ecologically or genetically).

 

 

Sharks are terrible - but also endangered

Keskiviikko 8.9.2021 klo 14.35 - Mikko Nikinmaa

The IUCN red list was again published. Although it is not able to give a full account of what the status of animal and plant species is, it gives an estimate of how nearly 140 000 species are doing in today’s world. There are some species, which are doing better today than in earlier year, but others, which are doing worse. Here I focus on fish, because they are of special interest to me. The red list information in full can be found at //www.iucnredlist.org/

The tuna species have long been among the endangered ones. However, it now seems that their stocks are recovering. This shows that if enough attention is placed on the status of a species, recovery is possible. The recovery of tuna populations is certainly due to the following: 1. The DNA of tuna catches has long been checked, so that catches including meat of the most vulnerable species could not be sold. This has directed tuna fishing towards the species not at risk. 2. The aquaculture of tuna has begun to be successful. This being the case, the need to fish natural tuna populations has decreased.

However, whereas tunas have started to recover, the same cannot be said of sharks and rays. Around forty percent of these cartilaginous fish are endangered. Virtually always, when sharks are in the news, they have killed or maimed a swimmer. Also, movies like the Jaws portray a negative picture of sharks. Consequently, they are considered to be evil, whereby very few people are against their disappearance. Yet, they are important components of healthy marine ecosystems, and the extinction of sharks leads to their deterioration. One of the main reasons for shark fishing is their use in shark fin soup. It has been considered a delicacy in Chinese cooking. In the quest for shark fins, only the fins were saved of the catch, and the rest of the shark thrown back to the water. Recently, there has been strong campaign against the use of shark fins, but at least as yet it has not helped the diminished stocks. The reason for this may be twofold: first, sharks reach sexual maturity late (often they are more than 10 years old), and reproduction is viviparous in many species with only a couple of pups born.

So, we should be worried about the disappearance of sharks. They are needed for keeping marine ecosystems healthy. The other animal group with a large proportion of species endangered is amphibians. They are suffering from the destruction of wetlands. Wetland destruction should be discontinued even if the purpose is not protecting amphibians, as it makes coastlands increasingly vulnerable to storms and flooding.

Temperature increases faster than fish can adapt

Tiistai 29.12.2020 klo 16.28 - Mikko Nikinmaa

A temperature increase will affect fish populations everywhere. Depending on the species, the depth of the aquatic body and its accessibility the effects can be drastic – the most extreme outcome being  the total disappearance of the fish from the habitat. Because of this, the research on temperature biology of fish has become an important field of study in climate change research. The importance of fish studies is strengthened, as they can be an primary source of animal protein in food.

Fish can be either stenothermal or eurythermal. The definitions indicate the phenotypic plasticity of species with regard to temperature. Stenothermal species tolerate only small temperature changes, whereas eurythermal species can live in wide temperature range. It should be noted that most of the preferred fisheries species have narrow genotypic temperature tolerance. If they live in environments with different temperatures, their genotypes are different, each still having narrow temperature tolerance so that the cold-temperature genotype would not be able to tolerate the temperatures that the warm-temperature genotype lives in and vise versa. Although a temperature increase may actually increase the amount of fish flesh produced per unit time, the species accounting for the increased productivity are not preferred catch or food.

The roles of phenotypic plasticity and the speed of heritable genetic adaptation to temperature changes has been surprisingly little studied. 

Further, it is almost completely unknown, if the temperature tolerance is affected by environmental contaminants. One important recent study with zebrafish (Morgan et al. PNAS 2020: https://www.pnas.org/cgi/doi/10.1073/pnas.2011419117) suggests that the genetic adaptation to increased temperature is not fast enough to keep pace with the temperature increase that is currently occurring. It also appears that the plasticity of tolerated temperatures decreases, when the population adapts to increased maximal temperature.

So, this is bad news throughout. The fish that we like to eat are stenothermal. The eurythermal species could substitute for them, but even they have problems in genetic adaptation. Furthermore, it seems that tolerance to reduced temperature evolves faster than that to increased temperature. All of these points make the case for markedly slowing down and stopping the current temperature increase stronger. If we want to eat fish, climate change must be stopped.

 

Hurricanes more long-lasting after landfall because of climate change?

Maanantai 16.11.2020 klo 13.23 - Mikko Nikinmaa

Hurricanes or typhoons – tropical cyclones cause immense damage because of the high-

velocity wind and heavy rain. A commonly accepted consequence of climate change is that the number of tropical cyclones per time period and their average strength increase both in North America and in East Asia. This is caused because the increase of oceanic temperature. Since the cyclones are fuelled by the moisture of air, and increased oceanic temperature increases air moisture above the ocean, the increased frequency and strength of hurricanes and typhoons is easy to understand.

Most of the damage is caused to coastal communities immediately after the landfall of the cyclones. Hurricanes weaken quite rapidly after the landfall, but a recent study in Nature (Li & Chakraborty, Nature 587, 230-247; 2020) suggests that hurricanes may weaken more slowly in a warmer climate. During the past fifty years the time taken for hurricane decay has virtually doubled. This appears to be due to the increase of moisture of the warmer air.

If hurricanes dissipate slower after landfall in warming climate, they cause damaga to larger areas than earlier. This adds to the need to increase actions against climate change. Even in fossil fuel energy were cheaper than renewable energy without taking into account the expenses caused in repairing hurricane damage, adding them to the costs would certainly stop fossil fuel use rapidly. Such climate tax could and should be added to the fossil fuel price at least in Europe, North America, Australia, Russia and China.

Why we need to change from intensive to environmentally friendly sgriculture

Torstai 12.11.2020 klo 19.23 - Mikko Nikinmaa

Intensive agriculture has relied heavily on ploughing and harrowing, fertilization and the use of pesticides. As a result, it has been possible to increase yields so much that whereas in 1960’s one was considering 5 billion humans to be maximum for feeding, there are now about 7.8 billion of us. Further, the absolute number of starving people has decreased, as the world population has increased beyond 5 billion. A success story? I am afraid not, only a temporary solution, which is currently being reversed: all the aspects of intensive agriculture are beginning to show their downsides. All of them indicate that intensive agriculture as carried out today is not sustainable.

First, soil fertility throughout the world is decreasing. The decrease happens fastest in tropical soils, but also the temperate, long-cultivated soils have recently started to show signs of becoming exhausted. The major reason for the loss of fertility is the fact that present agricultural practises are based on having fields without plant cover for a long period of time. Land without plant cover loses the most fertile topsoil as a result of leaching: if the land were covered with plants, much less soil would be lost when it rains or winds blow. Also, native land is a carbon dioxide sink, but ploughing and harrowing makes it a carbon dioxide source. It would certainly be possible to change agricultural practises to plant-cover requiring ones. To stop the decrease of soil fertility, that should be done. It should also be done, as the soil lost from fields ends up in rivers, lakes and the sea, causing their eutrophication.

To maintain soil fertility, artificial fertilizers have increasingly been used. Mineral phosphate deposits are overused, and much of the fertilization ends up in the aquatic environment contributing to eutrophication of water. To decrease flow of fertilizers into rivers and lakes, protective zones with plant cover are required. However, a much better alternative would be agriculture, which does not involve ploughing and harrowing.

Finally, the use of pesticides, especially insecticides, in copious amounts has been the landmark of intensive agriculture. Unfortunately, pests have begun to tolerate pesticides better and better, which results in increasing pesticide need to maintain efficacy. And this is not all; three quarters of all food crops require insect pollination, and it has clearly been shown that insect populations throughout the world are decreasing. Although definitive cause-and-effect relationships between insecticide use and decreasing population sizes have not yet been obtained, it is quite reasonable to suppose that it is the case. Instead of increasing use of chemical insecticides and other pesticides, biological control of pests has been advocated for the past fifty years. However, even though it would be much more environmentally friendly than the present chemical-dependent pest control, biological pest control has not become the most important way for controlling pests.

Thus, the very points that have been the cornerstones of increasing yields in intensive agriculture are now causing all sorts of problems ultimately leading reduced yields. There are alternatives to the present-day practises, but they require a complete change of cultivation methodology.

World Seas are in peril: Hypoxia in Baltic Sea as an example

Perjantai 5.6.2020 klo 18.40 - Mikko Nikinmaa

Human activities have affected world seas in various ways. A three-volume book on environmental evaluation of world seas has just been published by Elsevier (World Seas: an Environmental Evaluation). In two volumes it evaluates the environmental statuses of different sea areas and in one volume the major environmental problems affecting marine environments. The book’s aim is both to evaluate the present status and to evaluate the future of the seas. It would be impossible to give a comprehensive review of the book’s contents, so I take one environmental problem, hypoxia, in one sea area, the Baltic Sea as an example.

There have always been virtually anoxic bottom areas in the Baltic Sea, but they have increased markedly because of human actions. For example, the area with low oxygen (less than 2 mg/l) has increased tenfold from preindustrial times. The main reason for hypoxic/anoxic sea bottoms is that for about 50 years paper and pulp mill industry’s wastewater was entered the sea uncleaned. The biological oxygen consumption of the waste is approximately the same as that of 100 million people’s waste. Since the waste of tens of millions of people also entered the sea without treatment, the sea bottom now contains so much organic material and nutrients that even without any further wastewater or fertilizer discharges, the Baltic Sea would remain eutrophicated and have large hypoxic areas for tens of years.

Hypoxia is caused by the consumption of oxygen by organisms or organic material, if it exceeds the diffusion of oxygen from atmosphere and its transport from oxygen-rich waters. In the Baltic Sea the water is stratified, and the high-temperature, low- salinity water which is oxygen-rich does not circulate with the dense oxygen-poor bottom water. The bottoms get oxygenated water only, when pulses of oceanic oxygen-rich waters displace the bottom areas. When this happens, the low-oxygen water, which has high nutrient content, will be transported to lower depths and to  Gulf of Finland and also in small amount to Gulf of Bothnia. Because large amounts of phosphorus and nitrogen are liberated, primary production increases, and generation of hypoxia occurs in new areas. The increase of temperature causes increased oxygen consumption of all poikilothermic animals. Thus, climate change increases the likelihood of hypoxic periods. Also, if the predictions of increased rainfall during winter remain accurate, the phopshorus and nitrogen discharges during natural river flow to the Baltic increase markedly.

Although eutrophication is usually linked only to increased plant, algal and cyanobacterial growth, the end result is always hypoxia. In shallow areas eutrophication leads to intermittent hypoxia.               During the day, when there is enough light for photosynthesis, green plants and algae liberate oxygen, and the water often becomes hyperoxic. At night plants, algae, bacteria and animals all only consume oygen, rendering water hypoxic. The oxygen consumption by animals always consumes oxygen, but probably the most important reason for hypoxia is the oxygen consumption of microbes, which eat up all the dead plants, algae, cyanobacteria and animals entering the bottom. There is a group of bacteria which forms bacterial mats to bottoms with very low oxygen.

If one considers communities, hypoxia generally decreases diversity and changes species composition. As an example, at group level, fish disappear first, and are replaced by jellyfish. Among macrofauna, polychaetes survive at lowest oxygen level. With lowering of oxygen level, microfauna and microbes replace macrofauna. Hypoxia reduces the growth of animals and as a consequence fish catches are reduced. Additionally, hypoxia-tolerant species are usually of reduced commercial value. Thus, the Baltic Sea fisheries are markedly suffering from the spreading of hypoxic areas.

                 

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.

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. As 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.

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 between 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.

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)

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.

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.  

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.