Reprinted from Common Dreams.
Nature cheers us. Animals can be powerful, beautiful, sleek, graceful. A field of wild flowers chanced upon can take our breath away. Wordsworth so moved by 'a host of golden daffodils' put pen to paper, and we are richer for his poem. So it's distressing when scientists confirm our gut feelings about the human footprint on this natural environment. Wild Animals are no longer free to roam. Bordered by encroaching human populations they have been forced into shrinking invisible cages, leading inevitably to shrinking numbers. It is not a rosy prospect, while pollution and mounting plastic waste cause additional disasters.
Few people know that March 3 was World Wildlife Day, or
this coming Sunday (April 22) is Earth Day -- perhaps Trump
sucking up all the media oxygen is responsible. The fact remains, world
wildlife is under serious threat, and in ways we can't even imagine -- not
forgetting the eventual disaster due to climate change, unless the world wakes
Not too long ago Science, the voice of AAAS, America's largest science body, published three papers describing the harmful, even devastating, impact of modern human presence. These are encapsulated below, and should be of serious concern to anyone who cares for wildlife and the planet we inhabit.
The theme for Earth Day is End Plastic Pollution. If one ever wondered what can happen to a plastic bag discarded carelessly, the following research has a surprising and worrying answer.
This Science article looks
at plastic waste entering the oceans -- often through catchment areas and
into rivers that flow to the ocean. It assesses the influence of
such waste on disease in reef-building corals. The authors survey 159
coral reefs in the Asia-Pacific, a region containing 55.5 percent of global
reefs and 73 percent of the human population living within 50 km of a coast
-- about a quarter billion people.
Our plastic bag finally reaches the ocean and microbes hitch a ride on it, living longer and increasing their chances of landing on an unfortunate host: a coral reef. The authors have measured plastic items per 100 square meters. The count can vary from a low of 0.4 in Australia to a high of 25.6 in Indonesia. Size of human population in coastal regions, good management or mismanagement of plastic waste disposal are all factors in the amount of waste entering the water.
The study results are striking. The likelihood of disease from the microbes rises from 4 percent in areas free of plastic to a whopping 89 percent average when the corals have such debris. Another major issue is coral structural complexity which, importantly, underpins micro-habitats for reef-reliant organisms. Unfortunately, the study also finds that plastic debris is up to 8 times more likely to affect reefs with greater structural complexity. The resulting lack of habitat can devastate fisheries through a drop in productivity by a factor of three. Thus public awareness here could be a critical factor.
Next is a vast global study spanning
the four major continents and New Zealand. Authored by 115 scientists,
it traces the movement of 57 mammalian species through the GPS-tracking of 803
individuals. It finds a strong negative effect of the human footprint on
animal spacial mobility, threatening long-term viability unless the situation
The scientists develop a human footprint index (HFI) comprising multiple aspects of human influence: built environment, croplands, pastures, nighttime lights, roads, waterways, railroads, population density, etc. On the animal side, they note and separate the effects of resource availability and body mass on vagility (migration distances) -- larger species travel further as do carnivores.
They then compute animal movement as the distance between
subsequent GPS locations over nine time scales ranging from one hour to 10
days. At each time scale and for each individual, they calculate the
median (middle range) and longest distance movements. These procedures point to
the thoroughness of the research.
Overall the findings indicate a decline in movement of
mammals in high HFI areas ranging on average from one-half to one-third of
their movement levels in areas without human presence. For
example, the median displacement of carnivores over the 10-day period in high
HFI areas was only about half when compared to zero-impact regions. And
the long-distance movement over the same period in HFI areas was down to a
third, averaging 6.6 km versus 21.5 km. The impact on feeding and
breeding then is clearly severe.
The authors note the consequences for ecosystem function globally as the effects are critical for wildlife conservation and also in the spread of disease. In the latter aspect, the authors warn that "reduced vagility may go beyond ecosystem functioning to directly affect human well-being." In their understated words, it means the danger of accelerated animal extinction and human epidemics.
Most of us tend to assume all bees are good. Apparently not, as a couple of scientists explain. So as we reach for that honey jar ... it all depends on where it came from. That is the contention of the last paper, which assesses the impact of managed honey bees on wild bees and other pollinators.
Pointing to the rapid global growth in managed-bee colonies and the attention devoted to them, the authors believe this focus reduces efforts to preserve wild pollinators so necessary for wild plants and flowers. In fact, high densities of such bees worsen the decline of these wild pollinators, and have also been linked to the spread of disease via shared wild flowers. Long term this is a worsening threat to wild plants and flowers, many facing extinction.
The authors identify managed honeybees and their honey production and pollination of commercial crops as an agricultural issue, not an ecological one. They advocate restriction of managed-honey beehives in protected-ecological areas to reduce their harmful effects noting that half of all European wild bees are threatened with extinction.
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