I was listening to Danny Baker on BBC Radio 5 Live this last weekend and, whilst he may not have meant it, I think he made quite a profound point regarding water. Whatever water you wade in, it is all interconnected. So if you should fall into an agricultural ditch near Birmingham, you would be theoretically correct to say that you’re swimming in the Pacific Ocean – but ok, it won’t feel like it. Of course, water quality and quantity varies across the globe due to variation natural hydrological and climatological cycles but as a society, we’d do well to remember that all water is part of a global cycle. Water is owned by everyone, and no one. How we treat our local water should be the way we want others to treat it as it travels through its cycle.
Thinking about the life freshwater supports we can compare to some well known ornithological migrations. For example the superb feats of endurance by Arctic tern (Sterna paradisaea), which travels an average of 44,000 miles per year between Greenland and Antarctica or the more familiar swallow (Hirundo rustica) which migrates between northern Europe to sub-Saharan Africa can be matched by the European eel (Angula anguila), which migrates to the Sargasso Sea to spawn leaving the elvers (first hatch) to find their way home to freshwater streams. Or, consider the globe skimmer (Pantala flavescens) dragonflies. These insects make a staggering round trip of around 15,000 km between southern India to east and South Africa from their larval habitats which are small pools and rice paddies. These animals, and many more besides do not consider human boundaries, but they do have to suffer the often negative impacts that human boundaries present. Yet for people, animals such as these are key to the functioning of ecosystems upon which we rely.
To draw an anthropocentric parallel, the plastics within our marine environment have a similar length of migration, being carried huge distances to their own form of spawning grounds where plastic from all areas of the globe intermingle and entwine indefinitely. Up to 1,200 grammes of plastic per km2 of ocean can be found (Cózar et al., 2014), much of which is slowly being ingested by marine animals as they breakdown. Microplastics (less than 5mm) are ubiquitous and only in recent research are we beginning to reveal their full impacts on aquatic environments with some analyses suggesting up to 100,000 items per m3 of water or sediment (Eerkes-Medrano et al., 2015). These small plastic fragments, often from cosmetics, often bypass wastewater treatment and so remain for potential circulation amongst terrestrial ecosystems and human consumption.
So, the next time I am out walking by a river, or fishing in a lake I’m going to try and picture the Pacific Ocean. At the very least, it’ll make me think of somewhere warm as winter closes in! But it might also remind me that water is a global concern. Local action, whilst it may not feel like it, has a global pulse.
Cózar, A., Echevarría, F., González-Gordillo, J.I., Irigoien, X., Ubeda, B., Hernández-León, S., Palma, A.T., Navarro, S., García-de-Lomas, J., Ruiz, A., Fernández-de-Puelles, M.L., Duarte, C.M., 2014. Plastic debris in the open ocean. Proc. Natl. Acad. Sci. U. S. A. 111, 10239–44. doi:10.1073/pnas.1314705111
Eerkes-Medrano, D., Thompson, R.C., Aldridge, D.C., 2015. Microplastics in freshwater systems: a review of the emerging threats, identification of knowledge gaps and prioritisation of research needs. Water Res. 75, 63–82. doi:10.1016/j.watres.2015.02.012