The news arrived yesterday that one of Australia’s leading river ecologists, and also one of the most generous, kind and wise men I have known, died unexpectedly on Saturday 27 February. Keith Walker’s work in rivers spanned more than 40 years, much of it in the Murray-Darling Basin. For many, he was ‘Mr Murray’, because of his vast experience and knowledge of that river. He lectured and researched at the University of Adelaide for more than 30 years, and was fortunate enough to work (and publish) with Bill Williams, Jim Puckridge and many, many others. Keith edited The Ecology of River Systems (1986) with Bryan Davies and was an editor of River Research and Applications for twenty years. Keith sat on many, many committees advising on environmental issues and published more than 200 peer-reviewed and other articles. He had a long interest in freshwater mussels, and was always very happy to discuss these neglected, but important, animals. I was extremely fortunate to work closely with Keith, when we co-edited our book Ecology of Australian Freshwater Fishes (2013). His strength, tenacity and wisdom during those years, I will never forget. I learned so much, and was grateful every day to have his experience and gift for writing to guide us. His encouragement and enthusiasm never flagged, even when faced with the most recalcitrant of authors. All of those who knew Keith will miss him terribly. But we will also be grateful every day for knowing, and working with, a man such as him.
Detail of a Nilotic scene from internal decoration of a podium that surrounded the garden of the Casa del Medico in Pompeii. Two pygmies try to rescue their compatriot from being eaten by a hippopotamus. By Carole Raddato [CC BY-SA 2.0]
Classical Ancient Greek art largely featured humans or deities performing feats of courage (wrestling lions, stabbing minotaurs – that sort of thing), fighting battles or involved in calmer domestic situations. Indeed, Ancient Greek mythology provided a rich source of material for Greek artists. But Classical Ancient Greek landscape painting
was virtually non-existent. Instead of actually portraying landscapes – and riverscapes for that matter – gods and goddesses were illustrated as embodiments of the environment (see Classical Ancient Greek Art
). Ancient Greek art took a surprising and bold turn, however, following the death of Alexander the Great in 323 B.C. And it was art of the subsequent Hellenistic Age, which greatly influenced those young upstarts, the Romans – as it did many other societies around the world – for centuries to come. Continue reading
By Brendan Ebner, Tropical Landscapes Joint Venture, CSIRO Land & Water and TropWATER, James Cook University, Townsville, QLD.
A Wet Tropics stream just waiting to be snorkelled
Freshwater ecosystems are some of the most threatened on the planet. Freshwater fish are particularly imperilled: worldwide, 46% of all fish species are considered to be at risk of extinction by the International Union for the Conservation of Nature. It’s a very sobering thought that things are in such a bad state. But scientists, conservationists and natural resource managers are working hard to try to turn this around. One of the fundamental needs for all of this work is to determine the population size and distribution of fishes in rivers, and especially those fishes that are rare. Common ones are relatively easy to find, as any fisher will tell you. But it is the rare species – and these are often the ones that are at greatest risk of extinction – that we want to know most about, but are the hardest to find. It is an issue that fish ecologists have been grappling with for years. Interestingly, progress is being made, and increasingly includes a mix of low-tech and high-tech solutions. Continue reading
A recent paper in BioScience, co-authored by Keller Kopf, Max Finlayson, myself (all Charles Sturt University), Neil Sims (CSIRO Land and Water) and Sally Hladyz (Monash University), sets out to ask: how can we measure change in human-dominated freshwater ecosystems, given that most are unlikely to be able to be restored to historical conditions? We propose the new concept of Anthropocene Baselines. This concept recognises that remnants of historical ecosystems have great value, in all senses, but socio-economic and/or ecological constraints commonly prevent complete restoration. If it is not appropriate to measure change relative to an unachievable historical baseline, what do we do about this? To find out, read the whole article here.
Naiade, Henri Fantin-Latour, Hermitage Museum, St Petersburg
Although water plays a prominent part in Classical Ancient Greek myths and legends, it is saltwater that tends to dominate. Understandable, given Greece’s location, surrounded by the Aegean, Ionian and Mediterranean seas. Mind you, the Greeks did think that the world’s water was all one body, the global river, Okeanos, which surrounded the earth and was itself personified by the eponymous Titan. So rivers, per se, are largely absent in Ancient Greek artwork, in a similar way to the art of Ancient Egyptians. But rivers appear in art as mythological creatures, such as water nymphs and gods. Continue reading
Nun, god of the waters of chaos, lifts the barque of the sun god Ra (represented by both the scarab and the sun disk) into the sky at the beginning of time (Wikimedia commons).
In the beginning
Water features strongly in the creation myths of many civilizations. The Ancient Egyptians were no exceptions. At Heliopolis, for example, people believed that in the beginning there was only the surging, chaotic water, Nu or Nun. And from that chaos rose a mound of earth, and on that mound Atum, the creator, came into being. Continue reading
If you haven’t heard of George Monbiot, you should have! He is a gifted story-teller and environmental activist, and I love reading his articles, which are diverse and well-thought out. His credentials are excellent (read his bio for some interesting history of his exploits when he was young), his knowledge and interests broad, and his writings impressive and inspiring. He writes for the Guardian and his articles are on his website.
I was especially taken by his recent article entitled Everything is Connected, and reminded me of the wonderful video and story associated with the reintroduction of wolves to Yellowstone National Park 20 years ago (that he narrated). He and others at the Sustainable Human organisation have produced another video on the theme of whales and whale poo. It is well worth a look. It is called How Whales Change Climate.
Both stories are based on the concept of trophic cascades. In trophic cascades, the effects of predators ‘cascades’ down through the trophic (feeding) levels, to their prey, their prey’s prey and so on, in sometimes counter-intuitive ways. A big fish, for example, eats a smaller fish, which in turn eats zooplankton, which grazes on phytoplankton. These ‘top-down’ effects can be substantial and have been considered important for maintaining biodiversity in a number of ecosystems. See, for example, Fabrizio Sergio‘s work on raptors and Julia Baum‘s and Boris Worm‘s work in oceans. I will post a blog devoted to trophic cascades and rivers in the near future.
Of course, there are many more interactions in nature besides trophic cascades that structure ecosystems. But the appeal for me as an ecologist and as a teacher of ecology is that stories involving trophic cascades show really nicely the interconnectedness of components of ecosystems that we might not, at first or even second and third glance, think are connected. Trophic cascades also warn against complacency: that if we affect one component of an ecosystem, we are most likely creating a ripple effect that can carry far beyond the original disturbance.
I hope you enjoy George Monbiot’s writing.