FURTHER EVIDENCE THAT THE ECOSYSTEMS OF THE WORLD ARE ALL LINKED is provided in a recent report published in the journal Nature Ecology and Evolution. Samples taken in the Pacific Ocean from the deep sea Mariana and Kermadec trenches have demonstrated the presence of chemicals banned in the 1970s, in the fatty tissue of amphipod crustaceans. It is evidence that the deepest waters in the oceans are ultimately connected to what is happening at the surface and on the land. The two pollutants highlighted were polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). These were widely used as electrical insulators and fire retardants before being banned due to worries of them accumulating in the environment. Disturbingly, the levels of pollution were found to be on a par with samples taken from Suruga Bay in Japan, one of the most heavily polluted zones in all of the North-West Pacific. The accumulation and concentration of pollutants such as these is not dissimilar to the way DDT was concentrated in the tissues of apex predators, particularly birds of prey, during the fifties and sixties. Many of you will be familiar with the huge decline in the UK of raptors like peregrine falcons and sparrowhawks during that period, largely due to poor breeding success as a result of thin-shelled eggs due to DDT poisoning. All these issues demonstrate the ongoing and cumulative effect of pollution and the longer-term effects it can have even after the pollutants have been withdrawn.
Coral bleaching
Continuing on the theme of pollution, the effects of global warming are unfortunately rearing their ugly head again on the Great Barrier Reef with severe coral bleaching being reported for an unprecedented second year in succession. The coral has had no time to recover from the serious bleaching event of 2016 and scientists are genuinely worried about the medium-term survival of large sections of the reef. Sea temperatures have been at a higher than normal level throughout the last year including during the winter, and much of the newly bleached coral may die over the next six to 12 months. Closer to home, the charity Plantlife is drawing attention to what it considers to be a greater immediate threat than global warming, that being the increase of reactive nitrogen in the environment. The main sources of this are the emission of nitrous oxides from the burning of fossil fuels in power stations and through vehicle emissions, and ammonia from agriculture. Indeed, in 2014 it is estimated that 83% of all ammonia emissions were from agriculture, with the greatest
contributor being animal manures, particularly from cattle. These
pollutant gases undergo various chemical changes in the atmosphere and are ultimately deposited on the land as “dry” deposits or through precipitation. The significance of this? Much of
the diverse plant life that exists has evolved to thrive in conditions of low to medium fertility when it can compete effectively with more robust, fertility-loving plants. Increase the availability of nitrogen and species such as nettles, hemlock and cleavers thrive, whereas more sensitive species such as harebells, orchids and
many lichens decline as they are unable to compete. Plantlife says that reactive nitrogen is a much more immediate threat to UK habitats than global warming and that greater efforts need to be made to curtail atmospheric pollution with the offending gases.
For those of you who would like to find out more, go to www.plantlife.org. uk and download the report: We need to talk about Nitrogen.
