Rhythmic functions are disturbed by environmental changes

Sunnuntai 2.2.2020 klo 19:39 - Mikko Nikinmaa

Virtually all physiological functions show circadian and seasonal rhythms, with light (day and night, long daylength in summer and short light period in winter) as the major synchronising factor. Light-temperature interactions have been used as reliable indicators by animals for timing of reproduction, winter sleep or hibernation, changes of protective colouring and so on. The temperature increase associated with climate change has made light rhythm unreliable predictor of suitable time to carry out the function that has evolved to use the light rhythm as a reliable cue. As an example, short daylength has indicated to hares that it is time to change to white winter colouring. Since the temperature has increased so that there is no snow in latitudes, which earlier had it, the light cue results in white hares in dark background. Foxes certainly like easy hunting. There are various temperature-dependent responses of fish, which are signalled by light rhythm. Because of light-temperature interactions have rapidly changed, it is, for example, possible that hatching of fish takes place at a time that the larvae have no food after the yolk sac has been used up. In addition to the increase of temperature the oceans are suffering from decreased oxygen level (hypoxia). Hypoxia disturbs the generation of rhythms. Also, several environmental pollutants found in the aquatic environment affect rhythms. Consequently, temperature changes, hypoxia, and environmental contaminants affect aquatic life by affecting rhythmic functions. Because of this and because of interactions between temperature, hypoxia and contaminants, effects on sea life can occur after much smaller changes of any of the environmental conditions than hitherto supposed.

Kommentoi kirjoitusta. Avainsanat: climate change, hypoxia, environmental contaminants

Microbiota and environmental pollution

Sunnuntai 26.11.2017 klo 17:40 - Mikko Nikinmaa

All animals contain microbes, often billions of them.The symbiosis between the host and its microbes is essential for the well-being of the animal. Two examples of this show how important it is. If one is eating antibiotics, the gut microflora becomes disturbed, and, e.g., diarrhea can be the result. Ruminants utilize bacteria for digesting grass. Because of the fact that microbes are affected by completely different toxins than their animal hosts, surprising effects of environmental pollutants can be observed. For example, some herbicides may affect the necessary microbes of man, and because of this, although the effective compound does not exert any toxicity on the animal itself, by disturbing the microbial community of the animal, it may influence its well being. Effects of environmental pollution on the microbiota of animals is so far poorly studied - and is undoubtedly one area, which will receive important attention in the future.

Kommentoi kirjoitusta. Avainsanat: contaminants, non-target organisms, synergism