Rivers and oceans are easily neglected when it comes to pollution. Out of sight, out of mind and all that. Except that the oceans do not forget. Of all the water pollution problems, oxygen loss is probably one of the more abstract ones. Even the words used to describe it, hypoxia and anoxia, will be meaningless to those without a background in biology. In Dead Zones, marine scientist and microbiologist David L. Kirchman provides a general introduction to the problem of oxygen loss and why it matters.
Dead Zones: The Loss of Oxygen from Rivers, Lakes, Seas, and the Ocean, written by David L. Kirchman, published by Oxford University Press in April 2021 (hardback, 224 pages)
I thought you could not tell me anything new on this topic. After all, for my PhD, I spent five years in Finland studying how fish behaviour in the Baltic Sea is affected by eutrophication, the pollution caused by excess nutrients. The Baltic is one of several badly affected water bodies in the world due to the large land area that drains into it and the narrow connection with the North Sea. However, my studies focused on decreased underwater visibility due to algal blooms rather than oxygen loss. Dead Zones was thus a welcome surprise and refresher, showing that even I had only an incomplete picture of the problem.
So what are dead zones? They are areas of fresh or marine water that have low (hypoxia) or virtually no (anoxia) dissolved oxygen. As Kirchman clarifies in his prologue, the term is a bit dramatic. It does not mean that the whole water column is affected, often it is limited to the bottom layer. And they are not always completely dead, some organisms actually thrive here. But many creatures are sensitive to oxygen loss, leading to slower growth, fewer offspring, and poorer health. In extreme cases, it leads to the death of fish and bottom-dwelling invertebrates, reduced biodiversity, and reshuffled food webs.
Dead zones vary in size through time, influenced by weather and currents. But since about the 1950s, they have been steadily growing both in size and number, and we know the cause. Fed by excess nutrients, algae bloom. When they die, the bacteria decomposing them use up oxygen quicker than it can be refreshed. But before we get to this point in our understanding, the first half of the book takes the circuitous route through the history of their discovery.
“[Dead zones] were a natural occurrence in the past, but the frequency and severity have increased, and it all centres on roughly 1950.”
Some of the first dead zones that were widely noticed were the Great Stinks. Not that long ago, many rivers running through bustling cities in Europe and the US received large loads of untreated sewage. The resulting bacterial feast would rapidly consume all the oxygen and then switch to sulfate metabolism, releasing hydrogen sulfide with its characteristic smell of rotten eggs. Wastewater treatment facilities brought this problem under control, with rivers recovering and fish returning.
Much harder to notice were the dead zones developing in coastal areas, such as the Gulf of Mexico or Chesapeake Bay, or inland seas, such as the Black Sea or the Baltic Sea. Kirchman takes you through their discovery in the 1980s and the research by Nancy Rabalais and others to address the question whether they have always been there? The answer required the meticulous collection of long time series of oxygen measurements and the study of sediment cores that record past oxygen levels. The conclusion is that, yes, they were a natural occurrence in the past, but the frequency and severity have increased, and it all centres on roughly 1950. How so? More nutrients, specifically nitrogen and phosphorus. Where did they come from? Artificial fertiliser used in agriculture. As discussed here, there have been naysayers, both in scientific circles and amongst farmers and industry, but the evidence is pretty convincing by now.
Although Kirchman does not explicitly mention it, the 1950s marks a transition period dubbed the Great Acceleration during which our impact on the environment boomed. And the increase in nitrogen and phosphorus release is one of many indicators used by scientists to define the start of the Anthropocene. Two key figures Kirchman introduces here are Fritz Haber and Karl Bosch. The former developed a process to cheaply and efficiently fixate nitrogen, the latter scaled it up for the industrial production of explosives and artificial fertiliser. The Haber–Bosch process was one factor facilitating the human population explosion driving the Great Acceleration. As Kirchman mentions, “Depending on your diet, about half of the nitrogen in your body came from a factory using the Haber–Bosch process” (p. 96), and Vaclav Smil is quoted as writing that, without it, Earth would probably have only half the human population it has now.
“[…] these problems have been […] difficult to tackle. One factor is the inherent complexity of the system. […] There is no one-size-fits-all solution.”
Having arrived at the status quo, the second half of Dead Zones explains why these problems have been so difficult to tackle. One factor is the inherent complexity of the system. Which nutrient is the limiting one runs the full gamut from nitrogen in marine waters (mostly) to phosphorus in lakes, and sometimes neither. There is no one-size-fits-all solution. Similarly, as Kirchman explains, fish kills are not a problem suitable for a bumper sticker slogan to rally behind: “Dead Zones Kill Fish and Fishery Jobs” (p. 128). The reality is more nuanced. Oxygen depletion can, for example, boost fish landings when fish flee hypoxic zones and become easier to catch. And this leads to the second factor: all these complexities make it very easy for those who stand to lose from tougher environmental regulations to call for more research, and for legislators to hesitate to implement anything. However, as Kirchman points out: “[…] we cannot ignore dead zones just because the effect of hypoxia is complex” (p. 133). To that end, he offers a range of solutions, including things that you, the reader, can do.
Dissolved oxygen levels in water was never going to win the prize for the sexiest topic. Given this inherent handicap, Kirchman’s conversational tone makes Dead Zones nicely accessible. However, I do feel that the overall structure and clarity suffer somewhat, although I cannot quite put my finger on the why. The narrative ricochets between different topics and some things are only touched upon (e.g. the rise of jellyfish, or the release of neurotoxins during certain algal blooms). I did enjoy the historical sketches, they are Kirchman’s forte. At only 172 pages, this book is not a thorough overview but more a general introduction. Since these topics are normally discussed in scientific journals, reports, academic monographs, and edited collections, it is an introduction that is long overdue.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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“There is a vast, arterial power humming all around us, hiding in plain sight” (p. 320). With these words, geographer Laurence C. Smith concludes his engaging and impressive book on the environmental history of rivers. Touching on a multitude of topics, some of which I did not even know I cared about, I found my jaw dropping more than once.
Rivers of Power: How a Natural Force Raised Kingdoms, Destroyed Civilizations, and Shapes Our World, written by Laurence C. Smith, published in Europe by Allen Lane in April 2020 (hardback, 364 pages)
For a big book on the environmental history of rivers, you expect some classical history, Brian-Fagan style. Rivers of Power does not disappoint and dishes out fascinating introductions to the ancient Harappan civilization in South Asia who mastered municipal plumbing two millennia before the ancient Romans, the early Mesopotamian cities that sprang up around the Tigris and Euphrates Rivers, and the importance to ancient Egypt of the Nile and its annual flooding.
But Smith ranges far wider—take his sections on more recent historical events that revolve around rivers. One of the decisive battles of the American Revolution was Washington’s nighttime crossing of the Delaware River which helped America win its war for independence with Britain. Or the sordid history of Britain’s opium wars in China, which relied heavily on shipping traffic up the Yangtze River and the opening of so-called treaty ports to force China to accept the importation of opium in exchange for goods the English wanted. These are both examples of historical episodes I knew little about, but for which Smith here provides context and background in a pleasingly compact manner.
Rivers can also influence human affairs in more roundabout ways and Rivers of Power includes some remarkable examples. The disastrous 1889 Johnstown flood changed the face of US law forever. When a neglected dam belonging to a gentlemen’s country club burst, it wiped this Pennsylvanian settlement off the map. When neither the club nor its millionaire members could be held responsible for the death and destruction caused by their negligence, the ensuing national uproar led to the introduction of strict liability laws, creating a culture of litigation that persists to this day. Similarly, Smith argues that the 1927 Mississippi flood changed the face of US politics for good. Herbert Hoover cleverly used the disaster for self-promotion, contributing to his victory in the next presidential election. But when he never made good on his promises to provide black sharecroppers with mortgage payments for land resettlement, it spelt the end of African American support for the Republican Party.
“Rivers can also influence human affairs in more roundabout ways […] The disastrous 1889 Johnstown flood […] created a culture of litigation that persists to this day.”
Smith possesses some serious writing chops and has contributed pieces to the Financial Times, New York Times, Wall Street Journal, and other major outlets. My jaw dropped more than once. The identity of the young German boy that historians now believe was saved from drowning and grew up to be an influential statesman? That reveal hit me like a bombshell. Some of the details of the aftermath of the Johnstown flood make for chilling reading. And the interview with a veteran of the Vietnam war, a war largely fought from riverboats in the Mekong delta, was particularly gripping.
And what of the topics I would otherwise snooze through? Normally, my eyes are likely to glaze over when you say “transboundary river treaty” or “mega-dam geopolitics”. Instead, I found myself reading with great interest about Laos’s unilateral decision to build dams in the Mekong River, or the current construction of the Grand Ethiopian Renaissance Dam in one of the Nile’s two main tributaries and the political upset this is causing in Egypt. Smith also makes clear the immense scale at which we are now modifying landscapes. No longer content with simply building dams and canals, China, India, and several African countries are in the process of rerouting whole drainage basins in megaprojects known as interbasin transfers. Rivers of Power will teach you as much about historical events as it does about current affairs.
The above is but a sampling of the numerous interesting stories and studies that Smith covers here. In a book that wanders this widely, there will inevitably be sections that are of less interest. For me, it was the last chapter on riverfront redevelopment projects. Instead, I wanted to read more about Smith’s own hydrological research. For example, I was surprised at how brief his mention of the upcoming SWOT satellite mission was, given that he has been involved in conceiving and planning it for nearly two decades. Short for Surface Water and Ocean Topography, it will map the whole of the Earth’s surface waters in 3D. At the same time, it is testimony to the huge amount of research that Smith has put into this book that he is not choosing the easy option of writing mostly about the topics he knows intimately.
“Smith also makes clear the immense scale at which we are now modifying landscapes. [Several countries] are in the process of rerouting whole drainage basins in megaprojects known as interbasin transfers.”
Despite the chapters appearing long at the outset, they have been divided into shorter subheaded sections, so I never found the book wearing on me. Although no references or annotations are given in the text, the reference section at the back is organised according to the same subheaded structure, so finding sources and more information is fairly painless.
If I have to gripe about something, I feel that Smith is sometimes a bit too neutral in his reporting. Riverfront redevelopment is all fine and dandy but is a luxury for nations that have off-shored their heavy industry. Or take Egypt, which has single-handedly commandeered most of the Nile’s water discharge through the 1959 Nile Waters Agreement: “A new international agreement […] is badly needed. Yet any reduction in the total volume of water flowing downstream is potentially devastating for Egypt” (p. 155). To call Egypt not acknowledging upstream nations a “glaring omission” as Smith does here is putting it mildly, it strikes me as a scandalous example of overreach by a single nation.
Furthermore, a chapter dedicated to the effects of climate change on rivers would have been prudent—coverage of it is now scattered over different chapters. There is, for example, the shocking fact that half of the world’s glacier-fed rivers are past peak water (this refers to the highest discharge rate from glacier melt). Or the increased likelihood of more extreme floods thanks to the Clausius–Clapeyron relation (warm water holds more water vapour and will result in more rainfall—in effect increased temperatures accelerate the evaporation–precipitation cycle).
But these are minor complaints. Overall, Rivers of Power is bristling with fascinating and skilfully told riverine topics. Though meandering widely, it remains captivating throughout thanks to Smith’s excellent writing.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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“Eager: The Surprising, Secret Life of Beavers and Why They Matter“, written by Ben Goldfarb, published by Chelsea Green Publishing in July 2018 (hardback, 287 pages)
Eager mixes equal measures environmental history with reportage on ongoing conservation and wildlife reintroduction programmes. To understand how we got to where we are, Goldfarb recounts the heydays of the American frontier times, when white settlers fanned out over the USA, killing, trapping, and hunting anything that moved. Bison, wolves, and the passenger pigeon are some of the better-known examples of animals that were virtually extirpated (see some suggested reading below), but there was an equally lively trade in beaver pelts. This sad chapter in history is explored more in-depth in Fur, Fortune and Empire: The Epic History of the Fur Trade in America and Once They Were Hats: In Search of the Mighty Beaver, but Goldfarb gives a good overview of the scale of the onslaught as trappers caught beavers by the tens of thousands in mere decades.
To understand why this was such a loss requires Goldfarb to invoke the specter of shifting baselines, which he poetically describes as long-term amnesia: “every year we lose more and remember less”. I have mentioned this syndrome before in my reviews of Vanishing Fish: Shifting Baselines and the Future of Global Fisheries and All the Boats on the Ocean: How Government Subsidies Led to Global Overfishing, but it does not just apply to overfishing. People simply forgot that beavers once roamed the landscape, forgot how their dams created meandering rivers with regularly flooded wetlands that are havens for diverse forms of wildlife large and small. Forgot how their dams maintained healthy groundwater levels, prevented flash floods, and tempered erosion. The denuded landscapes left in the wake of the ravages of the fur trade rapidly fell victim to overgrazing and trampling by cattle, the attendant erosion causing streams to rapidly cut through landscapes down to the level of the bedrock, lowering groundwater levels in the process. The impact of shifting baselines has been so pervasive that even some 19th-century biologists fell victim to it, which greatly hampered reintroduction efforts in for example California, as the prevailing opinion (even amongst academics) was that beavers had only existed in isolated pockets, and never at high altitudes.
“Goldfarb describes shifting baselines poetically as long-term amnesia: “every year we lose more and remember less””
Europe, which Goldfarb explores in chapter 9, fared even worse. Remember where all those frontier-immigrants came from in the first place? Centuries after Europeans had already hunted and trapped most wildlife out of their continent did they continue these lucrative but destructive campaigns overseas. Against this dark history, Goldfarb paints an uplifting picture of a current-day ragtag army of self-styled Beaver Believers: conservationists, landowners, environmental managers, even some cattle ranchers and farmers, who are fighting to reintroduce beavers and let them take over stream restoration.
We meet Mike Callahan, a former physician-assistant at a methadone clinic who invented flow devices: low-tech beaver-proof structures of pipes and fences that partially drain a beaver pond to prevent catastrophic flooding of nearby roads and properties, now highly in demand throughout the US. There is Nick Weber, a scientist who has been imitating beavers by constructing artificial dams that have beneficial effects on the hydrology of landscapes and are not infrequently colonised be returning beavers, giving them a leg-up when re-establishing themselves. Or Heidi Perryman, whose non-profit Worth a Dam has been ceaselessly campaigning for the benefit of beaver-dom, dispelling many myths and misconceptions in the process.
Goldfarb spends time with these and many others who are passionate about what well-known naturalist George Monbiot has called rewilding (see his book Feral: Rewilding the Land, Sea and Human Life). This is the idea of not just reintroducing species, but restoring functional ecosystems – not by micro-managing them, but by letting them run their own wild course. Speaking of Monbiot, Goldfarb touches on the viral YouTube video about the return of wolves to Yellowstone National Park for which Monbiot provided the narration. This hotly contested video makes it sound as if wolves have single-handedly changed whole ecosystems. Many ecologists accuse it of simplifying matters or of just being outright wrong, whereas others defend it. It is not unlikely that beaver reintroductions have played an important but overlooked part in this story, and I am happy to see Goldfarb bringing up the controversy around this video.
“Though it might seem as if Goldfarb is imbuing them with near-mythical powers, beavers are a keystone species”
But above all this rises the beaver – the unmistakable heroes of this book. Though it might seem as if Goldfarb is imbuing them with near-mythical powers, beavers are a keystone species – one that has an outsized effect on an ecosystem. This is clear from the environmental history that he so meticulously documents here, where the removal of beavers changed and destabilised whole landscapes. But it is equally clear from the spectacular results of current reintroduction projects. Beaver dams and their slowing down of rivers and streams have tremendous positive effects on both the biotic and abiotic landscape. Which is just academic shorthand for saying that they create environments suitable for living creatures (fish fry, amphibians, insects, birds, mammals, and plant species), but also have a positive impact on its geomorphology (e.g. the shape of landscapes, and rates of erosion and silt deposition) and hydrology (e.g. groundwater levels).
Though I have always had a superficial mental image of beavers as those dam-building rodents, I found Eager to be a revelatory and very interesting book. The regular castorid puns and rich alliteration might not be to everyone’s taste, admittedly, but overall my feeling was that the prose flowed off the pages into my eyeballs. Eager is clearly far more than a dry, scholarly treatise on the subject. In my opinion, Goldfarb here successfully advocates the beaver’s cause while also writing a beautiful book.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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