The Plague of Global Plastics

It seems an unstoppable ecological nightmare

We hear and read almost daily about the likely consequences of global warming and that various measures are being taken to stop it or at least to slow it down. However, it could be that global warming does not only produce ‘losers’, but that some regions could actually benefit from it,  be it by much reduced heating costs during winter, longer growth periods in the summer, prolonged open waterways and ports, fewer ice-related accidents, etc. But the ever-increasing amounts of plastics and their residues in our environment affect us all, from the tiniest organisms to the biggest in the sea, on land and in the soil.  And nothing appears to stop the ever-rising accumulation of plastics like polyvinylchlorides (PVC), polyethylenes (PE),  polypropylenes (PP), teflon, nylon and their additives.

Not only is it disturbing to see plastic bags caught in the branches of a tree or discarded plastic boxes along the wayside or plastic debris on our beaches, the problem is much more serious as what we see is just the “tip of the iceberg”. What clutters up the landscape are macro-plastics, the ones we notice, but so-called micro and nanoplastics as well as the chemical residues (that remain even after physical abrasion has led to the fragmentation of a plastic item) will still be around.  It is worrying enough that most plastics, having half-lives of hundreds of years, will not become degraded in one lifetime; but even more alarming should be that compounds, often added as hardeners like bisphenol A (BPA) and/or flame retardants like polybromides (BRFs), could make it up aquatic as well as terrestrial food pyramids and affect the health of individuals at the end of the food chain. The debate as to what are safe limits of the questionable compounds goes on, but there is evidence from a variety of species that plastic additives which get into the food chain can cause endocrine (= hormonal) and epigenetic disruptions, lead to fertility problems and possibly tumours, increase susceptibility to disease, affect longevity and adaptations to stressors. These invisible substances accumulate in mussels, fish, even whales, and in the form of fish meal, fed to poultry and pigs, may then be passed on to  humans.

However, not just thinking of humans, it has become abundantly clear that macro as well as micro and nanoplastics affect numerous species adversely and that the lower the molecular weight of a plastic, the greater its chance is that the polymer can be intracellularly digested by bacteria.  Floating plastic debris in the sea can be mistaken as jellyfish by especially turtles; it can accidentally snare individuals and impair their growth or kill them or it may unwittingly be ingested by fish and fill their stomach or clog up the digestive tract. Shocking photos have been published on the consequences of plastic debris-animal interactions in the sea as well as on land.  The pollution with plastics and their residues has no bounds, affects the world from pole to pole and has not even spared the deep sea or the remotest places on Earth. There are so called gyres in all major oceans that concentrate the floating plastics (there are more that would have already sunk) and the most infamous is the Great Pacific Garbage Patch twice the size of France and estimated to contain at least 100 million tonnes of plastics.

The tragedy is that we are all too hooked on plastics: they don’t break easily, are lighter than glass, wood and metal, are relatively easy to make, shape, mold, and transport and their production will not decrease. Will biodegradable plastics with less controversial additives ever be available or is that wishful thinking? The irony is that after the Englishman Alexander Parkes had invented the first plastic in 1862, the American John Hyatt patented ‘celluloid’ in 1869 to produce billard balls (thereby hoping to save elephants whose ivory used to be the source for billard balls until then). And what are the plastics saving now? Mainly money! And if it’s not already true, we are getting closer and closer to the pop artist Andy Warhol’s famous wish “I love plastic. I want to be plastic”.

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

How did Ludwig Von Bertalanffy Prevent Fish Species being Over-Exploited?

As more and more consumers turn away from meat, especially that of mammals, they do, however, turn to fish. Consequently, there is increasing pressure on fish stocks in the wild, but a growing opportunity for fish culturists to improve fish rearing facilities. When I was still a student of Fisheries Science in 1967 and lectures I attended dealt with fish stock assessments, catch per unit effort, fish populations, age structures, longevities and survival rates of fishes, time and again Ludwig Von Bertalanffy was mentioned and equations he had developed were quoted and written with chalk on the blackboard (yes, chalk and blackboard in those days). But why were Von Bertalanffy’s calculations so useful and why are they still part of the backbone of fisheries assessments of fish stocks today?

Ludwig von Bertalanffy was born near Vienna in 1901 and although his parents got divorced when he was ten, he did enjoy a good home education until then, when he became a grammar school student. He had the famous anti-Darwinist Paul Kammerer as his neighbour and soon began to apply his mathematical interests to biology and the living world. He is now often regarded as the founder of General Systems Theory, which has inputs from thermodynamics, cybernetics and biology. At the University of Vienna his fields of expertise could be called Theoretical Biology and Philosophy and in 1937 he got a Rockefeller scholarship to work in the USA. When he failed to secure immigrant status, he returned to Vienna in 1938 and joined the Nazi-party. After the war he found living in Austria difficult, moved to the University of London in 1948 and from there two years later to appointments at various American and Canadian universities. He died in 1972 in Buffalo, New York.

In his biological research, Von Bertalanffy was interested in psychology, psychiatry, development and growth phenomena and concluded that thermodynamic principles worked well in closed systems, but not in open systems like those comprising living organisms. He came up with a simple growth equation for biological organisms that models mean length of animals in relation to age:  L(a) = L_∞ [1 – exp (-k(a – a₀))],  where a is age, k is the growth coefficient, a₀ is the value used to calculate size when age is zero and L_∞ is asymptotic size (which means the rate of growth continually decreases as an individual ages but never completely stops). The equation above is the solution of the linear differential equation:  dL/da = k(L_∞ – L) and applicable to organisms that do not cease to grow when adult (unlike, for instance humans, which actually shrink when reaching old age), but keep growing albeit at increasingly slower and smaller rates as they age. Fish are some of these animals and since it is important for fisheries biologists to know at what age (or body length) individuals of a species become reproductive and therefore should not be ‘harvested’ until old enough to have reproduced at least once, it’s obvious that much emphasis has been placed on Von Bertalanffy’s growth curve that relates age to body lengths.

To make this relationship ‘work’, it is crucial to know how old a fish is at any given length. Helping fisheries scientists in this matter are age-rings on the scales of fish (not unlike those that one uses to age trees). The problem is that not all fishes live in climatic zones in which there are distinct seasonal changes that result in age rings on the scales and secondly not all fish species even have scales. In my research with the Polish scientist R. Traczyk, we worked with Antarctic icefish that have no scales and live in constantly ice-cold water. In such cases one uses daily increments of extremely narrow CaCO₃ layers, visible in sectioned ear-stones of the fish examined under the microscope. The layers provide an accurate estimation of the fish’s age that can be correlated with the fish’s total body length. What is then still left to discover is at what age and body length these fish spawn. For that to find out, fish have to be trawled near spawning grounds and females must be measured and examined as to whether they still have mature eggs in their ovaries or had already spawned. Once all the essential data are in, one can use the Von Bertalanffy growth curve to make recommendations to the fishing industry at what size it is ‘safe’ to harvest and market a species without depleting the population of younger and still immature specimens. Although Von Bertalanffy’s work doesn’t save all fish from being ‘fished’, it does help to ascertain that there are still enough youngsters around to maintain the population.

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

Also a Pandemic

But who cares?

There are times when everyone is talking about ‘pandemics’ and it is, of course, something to worry and to take action about. But there are not only pandemics that affect human health directly, but pandemics amongst animals that can not only be devastating for the animals themselves but indirectly for humans as well. For instance, the so-called African swine fever, a terrible and frighteningly contagious viral disease of pigs that is killing domestic and wild pigs around the world. Although it has not yet reached North America it is estimated that in 2019 alone 300 million pigs had to be killed or died in China and that by now the disease has spread to 50 countries. Affected pigs (and no age group is spared) develop a high fever, lose their appetite and can die within a week after being infected. Humans can’t catch the disease, but can transmit it to other still healthy pigs. The foot-and-mouth disease is another livestock disease caused by a virus and affects all species with cloven hoofs. The disease spreads very easily and although lethal in adult animals only to about 5%, it can have a severe effect on the health of calves, lambs, and piglets killing 20% of those that are still receiving milk containing the FMD-virus from their sick mothers. That birds, too, can be sick and their illness can reach the level of a pandemic, we know from the bird flu that started in Hong Kong in 1997 and then arrived in Europe in 2004 where it lead to the controlled killing of millions of domestic chickens, ducks, and geese.