Freshwater ecosystems in New Zealand are under threat for many reasons. They include mining, forestry, urban development, water abstraction, intensification of agriculture, the presence of invasive species and, potentially, climate change. Many of the rivers, streams and lakes most at risk of environmental degradation are in lowland and coastal areas where human populations are predominantly found and where the landscape has been heavily modified to support urban development, industry and farming. New Zealand is hardly unusual in this respect as rivers around the world have long been used as conduits for transportation, rubbish disposal and focal points around which towns and cities have developed. Locally, Christchurch provides a typical example with the Heathcote River being described as an open sewer soon after its formation.
In Polluted inheritance, Mike Joy focuses particularly on degradation of freshwater through the intensification of agriculture, most notably the recent expansion of dairying. Dr Joy is well known to many New Zealanders as a provocative environmental advocate through his many talks to a wide range of interest groups, and as a magnet for the media. His no-holds-barred stance on the need for environmental protection, most notably the protection of freshwaters from the excesses of farming, has made him a polarising and often controversial figure. However, like him or not, his advocacy for clean freshwaters and the need for New Zealand to ‘clean up its act’ has arguably drawn the attention of more people to environmental issues than has any other single individual in recent times. Polluted inheritance is a very short book, perhaps more of a pamphlet or essay, and barely does justice to its subject. It was born out of talks given by the author and, inevitably, its text of 54 pages plus notes only skims the surface of the topics he introduces. For example, the condition of lakes and groundwaters each receive less than a page of text. Although it is highly readable I would like to see Dr Joy write another longer, more strongly documented book. More extensive scientific referencing of facts, claims and counterclaims, than could be provided in the present book is needed to both strengthen his arguments and convince his critics.
In his short introduction, Joy notes the widespread loss of forests, wetlands and other land cover in New Zealand since European colonisation and the associated losses of habitat for native plants and animals. As an example he emphasises the multiple functions of wetlands (but does not define them) as soil and sediment filters, bio-accumulators, climate regulators and flood-energy dissipaters, their historical use by Māori as ‘food store, pharmacy and fibre supply’ (p. 9), and their major role in the decline in freshwater biodiversity found in New Zealand today. He argues that the loss of ecosystem services (e.g. nutrient stripping, flood mitigation and water storage) formerly provided by wetlands worldwide has had devastating economic effects and costs the global economy trillions of dollars per year. New Zealand’s remaining wetlands and many other freshwaters need substantially greater and more transparent environmental protection if their viability as functioning ecosystems is to be maintained and enhanced.
Significant human impacts on rivers result from activities in their catchments. Mining, forestry and urbanisation provide obvious examples. Joy’s main focus is on the effects of nutrient and sediment inputs and the negative impacts they have on the physico-chemical environments and biodiversity of rivers. Unacceptable increases in nutrient concentrations lead to organic pollution, associated increases in the productivity of algae, aquatic plants and bacteria, and, in extreme cases, major losses of dissolved oxygen. In turn, these changes result in habitat changes that have negative effects on populations of benthic invertebrates and fish to an extent that they may be lost. Likewise, excessive inputs of sediment accumulate on river beds or may remain suspended in the water as it moves downstream. Once again fish and benthic habitat is lost, sometimes downstream distant from the source of the problem, where accumulated sediment may result in ecological damage. Joy highlights the effect of human impacts on aquatic biodiversity by noting that 74% of native freshwater fish are considered to be threatened species. Extraordinary as this figure is, it should be noted that the natural habitats of a majority of our freshwater fish are in lowland waters where environmental degradation is most extensive.
The deteriorating state of water quality in New Zealand is discussed using long-term environmental monitoring studies undertaken by the National Institute of Water and Atmosphere (NIWA) and regional councils which have compiled valuable datasets relating to water quality, invertebrate communities and fish populations on a wide range of streams and rivers. Joy rightly emphasises the need to use long-term data to draw conclusions about temporal changes in stream health and is in no doubt that overall conditions are getting worse. Brief comments are also provided on pollution of lakes and groundwater, faecal contamination and human health, and contamination of soils by cadmium. The latter section departs from the primarily water-oriented focus of the book despite the effects of heavy metals on stream faunas by mining being well documented in New Zealand.
So how did this freshwater crisis come about? Joy is in no doubt that intensification of agriculture, made possible by huge increases in the application of fertiliser and animal feed in the last few decades, has had the greatest impact. We are told that New Zealand is now the single biggest palm kernel importer globally, and that production driven by external inputs ‘inevitably degrades the environment as stocking rates exceed its ability to assimilate the cumulative impacts’ (p. 34). An important observation he makes is that cow urine produced in volumes greater than can be absorbed by pasture eventually finds its way into water and cannot be prevented by fencing streams or planting riverbanks alone. While such activities may provide bank protection and keep stock out of waterways, with respect to nitrogen pollution they are essentially ineffective.
Dr Joy argues that most dairy farms could cut pollution significantly and boost their profit by reducing the size of their herds, as he believes that ‘marginal’ cows add no profit and the cost of keeping them outweighs the income realised from them. He also calls for much stronger enforcement of the Resource Management Act to protect the environment from degradation. Unsurprisingly, he also argues that government decisions need to take into account the costs of degradation including losses of ecosystem services, functions and biodiversity. Without such an approach he foresees even greater environmental damage if dairy conversion and intensification continue. His initial requirement for a better future is that all parties must accept the reality of environmental degradation and take serious account of the value of ecosystem services in reversing such declines. Greater enforcement of stronger legislation is seen as the key to reversing the decline of freshwater ecosystems in tandem with continuing education of the public.
Mike Joy’s main message is hardly news to environmentalists. His solution to the freshwater crisis is to get science, farming, economics, government and the people of New Zealand singing from the same hymn sheet. How difficult is that?