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.

Kommentoi kirjoitusta. Avainsanat: aquatic toxicology, water pollution, gill function, hypoxia

World Bank: Anhropogenic Contamination of Aquatic Resources Reduces Economic Growth

Keskiviikko 4.9.2019 klo 18:16 - Mikko Nikinmaa

Just recently, the World Bank published a booklet: Quality Unknown. The Invisible Water Crisis. What it basically says is that the water resources throughout the world are so much affected by human actions that it causes a significant slowing down of economic growth. Reading through the booklet, there is naturally no big news to us water researchers, but it is a good summary of the things that are anthropogenic problems in our water resources, and how these problems affect agriculture, industry and our everyday affairs. However, I bring the World Bank document forward, because earlier on economy and environment have always been brought forward as opposites. And virtually in every case that economic and environmental considerations have clashed, the environmental one has lost. The World Bank report gives a sad tale of what the result is. Economic growth is slowing down largely as a result of decisions, which have been taken in order to boost economy. This indicates that economic thinking should be changed so that environment (natural capital) is primary and must be maintained in good condition. All economic actions must be done so that if they harm environmental balance in one dimension, they must improve it in another so that the overall status is not affected. It is the path to sustainability.

The Quality Unknown report can be found at www.worldbank.org, where also the ideals of the World Bank are brought forward. Quickly reading through them, I feel that should be the direction that economic thinking in united world goes to.

Kommentoi kirjoitusta. Avainsanat: natural capital, water pollution, sustainability

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.

Kommentoi kirjoitusta. Avainsanat: aquatic toxicology, oil spill, water pollution, fish kills

Hydrogen sulphide - both toxicant and a cell signalling molecule

Perjantai 13.10.2017 klo 11:53 - Mikko Nikinmaa

With increased eutrophication many aquatic bodies have anoxic bottom sediments. They are characterized by high concentration of hydrogen sulphide, smelling of rotten eggs. Hydrogen sulphide is considered to be a highly toxic substance, and together with the lack of oxygen contributing to the death of organisms in the hypoxic areas. This may be so, but the initial effects disturbing the functions of organisms may not be caused by the traditionally considered effect of sulphide disturbing aerobic respiration.

It has recently become clear that hydrogen sulphide is an important cellular signalling molecule, in various cases the "oxygen sensor" of the cells. Thus, variations in its cellular concentrations fine-tune oxygen-dependent effects tp occur appropriately. Consequently, any disturbances in the level of hydrogen sulphide can disturb cellular signalling, and harmful effects can take place because of disturbances of cell signalling even when the concentration would not be adequate to cause breakdown of aerobic respiration and death because of that.

Kommentoi kirjoitusta. Avainsanat: hypoxia, water pollution, cell signalling

Living in the city - for the sake of environment

Lauantai 5.8.2017 klo 18:27 - Mikko Nikinmaa

An environmentalist's dream is to live in unpolluted countryside far away from all the terrible problems of cities. However, if one thinks from the environmental point of view, living in compact cities is the choice one should take. Compact cities are the best choice for environment for many reasons, some of them outlined below:

1. In cities one can go from place to place walking, by bike or with the use of effective public transport. Owning a car is not necessary to get from place to place, and as a result of this the use of fossil fuels can decrease drastically. If people lived in the cities, transport between places would not require the present intensive car traffic, and thus roads would need less maintenance: the change from private cars to public transport between cities would also be the environmentally right thing to do. There are naturally places which individuals or families would want to see, which are not in the routes of public transport. To enable doing this, public vehicles, which people can use, should be made available (naturally electric cars).

2. Effective water cleaning with reasonable costs can only be done in compact cities. Effective water cleaning plants are only possible with proper sewage systems. With big water and other trash treatment units one would be able to generate most of the energy required for heating/cooling buildings in the city. Only a fraction of the sewage would be going to the environment unmodified as compared to the situation today.

3. Compared to today, recycling could be done much more effectively. If most of the metals were reused, the need for mining would decrease drastically. I don't think this would even be more expensive than mining and processing of the stone to metals - it would just require a change in attitudes. The same is actually true for the reuse of cloth.

4. Effective energy production and distribution could be best done in compact cities. They could be energized largely individually with the help of solar and wind power, and with the heat generated during waste treatment.

5. Instead of the massive tourism and other air traffic, modern technology could make connections between people possible without travel. I do not think that there can be such a thing as ecotourism. Going to see environmentally unique places means that their unique features diminish. This is a real problem for example for tourism to Finland. Finland markets itself as a place, where tourists can be in undisturbed nature with few other people. If the marketing is effective, there will be a lot of people seeing areas which have been disturbed by earlier tourist herds.

Utopy? Maybe, but that is the direction we need to take. By living in the cities we can reduce the human impact to the environment.

Kommentoi kirjoitusta. Avainsanat: climate change, air pollution, water pollution

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

Electric Cars - not just for the sake of the use of fossil fuels

Tiistai 6.6.2017 klo 13:52 - Mikko Nikinmaa

When one is advocating the transition from gasoline-using cars to electric cars, one normally only speaks of climate change, and decreased use of oil. Naturally the eletric cars will only diminish climate change, if the electricity is produced with renewable resources (and at least in short term, renewable energy excluding wood-burning). However, there is at least one other significant point associated with electric cars.

Much of the pollution of the seas is caused by oil spills, either deliberate or accidental. If the need of gasoline in the cars and other vehicles of the world decreased, the oil pollution would be drastically decreased. The water pollution aspect also speaks against changing oil to biodiesel. The product would still have to be transported, and accidents would still happen. For a bird that is affected by the spill it does not make any difference if the spill is of fossil oil or biodiesel. So, in fact, all inventions, which enable diminished use of oil or biodiesel in heavy vehicles, are a very important part of trying to limit marine pollution.

Kommentoi kirjoitusta. Avainsanat: climate change, water pollution, oil spills

Eating fish - but wild-caught or cultivated?

Maanantai 3.4.2017 klo 13:06 - Mikko Nikinmaa

Fish is, in principle, health food, and also good in terms of climate change. As insect eating has recently been advocated as an environmentally friendly way of actually eating meat, one needs to point out that from energetic grounds fish eating is just as good. Both insects and fish are ectothermic animals, which convert feed to meat at much higher efficiency than cows or swine, because no energy needs to be wasted to maintaining body temperature.

So, it is good to eat fish, but should it be wild-caught or cultured? The world's seas are heavily overfished. The gloomiest predictions estimate that close to half of commercially fished species become extinct within the next century. Despite the overfishing, several nations and the European Union have given large funds to the development of fishing fleets, and more effective fishing gear. At the same time the same instances have pledged to maintain the biodiversity. So, the actions are in fact opposite to promises and only serve to speed up the decrease of biodiversity. In addition to fishing causing the exctinction of species, the problem with wild-caught fish is aquatic pollution. Most pollutants are taken up and remain in the bodies of fish, because they are hydrophobic, whereby their preferred site is the body and not water. Many of the pollutants further bioaccumulate along the food chain.

So, eating wild fish is, in principle, a worse alternative than eating cultured fish. However, there are several things that make the present aquaculture practises problematic for ecologically responsible fish-eater. First, most cultured fish are carnivorous, and their feed largely consists of fish flour. So, in such a case the big fishing fleets will continue to decrease the fish diversity, now not to get food for humans, but to get resources for feed factories. The only sustainable way is to replace some of the fish flour in feed with plant product. This is a direction to which several fish feed companies have recently gone to. Second, aquaculture causes local eutrophication because of the feed and faeces, which have high amounts of nutrients. The way of prevent this would be to have aquaculture facilities separated from general aquatic environment so that all the water used could be purified. One should here point out that the cultured fish do not produce more faeces than the natural populations - the difference is that they are concentrated in much smaller areas. Third, the use of antibiotics and other drugs in aquaculture facilities is high, because parasites and diseases are much more prevalent in the dense aquaculture  populations than in the natural populations. For improvement of situation with regard to this, it would also help, if the aquaculture facilities were separated from natural wateeeeer flow. Also, the use of antibiotics should be discouraged.

In conclusion, it is possible to make aquaculture environmentally friendly, but after that is done, cultured fish will not be the cheapest food that can be found. But we should be ready to use some money to use ecologically sustainable foodstuffs.

Kommentoi kirjoitusta. Avainsanat: biodiversity, water pollution, fish feed

Are there no environmental effects associated with coal burning?

Lauantai 18.2.2017 klo 15:49 - Mikko Nikinmaa

Industrialization started with the use of coal. Immense amount of energy could be obtained for industry and housing by burning coal. However, already in the early 20th century its clear negetive effects were seen. We all know London fogs - they were mostly caused by coal burning to heat housing. They have virtually disappeared now that coal use has diminished. Another clear effect was the so called industrial melanism. Certain butterflies became darker, because all the surfaces in industrialized areas had dark coal dust. The change was hereditary indicating rapid evolution. Now that coal dust accumulates less on surfaces in the British Isles, also the colour of butterflies has become lightier agan. In China it is estimated that the coal dust in the cities makes up to millions of respiratory diseases more serious.

Against this background it is incredible that the new US administration has now decided to abolish restrictions of allowing coal-associated wastewater to enter streams and lakes. It is equally scary that very strong support for both Brexit and Trump's presidency was obtained from people, who imagined that coal-mining and coal-based industries could be brought back, even though that is definitely not possible. Instead of trying to go back to the past, one would need to find new solutions, and generate new coal-independent livelihoods. It is equally incredible that the head of US Environmental Protection Agency is a person, whose major goal earlier has been to close the agency.

Kommentoi kirjoitusta. Avainsanat: fossil fuels, energy production, air pollution, water pollution