Salt marshes: their role in our society and threats posed to their existence

Introduction to World Seas: An Environmental Evaluation Charles Sheppard This three-volume set, World Seas: an Environmental Evaluation, is in many ways a second edition to the three-volume series published in 2000, Seas at the Millennium (Sheppard, 2000). It contains more than 100 chapters in three volumes: the first two volumes review the coasts of numerous countries or regions around the world (some of the longer chapters embracing very large areas), while the third volume addresses global issues. In the last couple of decades, it is clear that there has been a continued, one could say relentless, decline in the world's shallow marine environment and habitats. This affects most places, and has happened during the time when the quantity and the quality of marine science have increased immeasurably. A benefit of the latter is that it has enabled us to document with ever-greater certainty the deteriorating condition of the marine environment and to show that, by and large, the relentless trend of decline is being caused by continued unsustainable extraction of marine resources and by direct habitat damage. Overall, the rate of damage now far exceeds the ability of the main shallow ecosystems to restore themselves. In some regions, particularly the wealthy countries, major advances have been made to, for example, water quality, and sometimes definite and very clear improvements are evident from the condition that existed two decades ago. Naturally, this is good and encouraging, and while these serve as a model for everywhere else, they are unfortunately evident and significant in a minority of cases. Similarly, with some of the global impacts, controls are being introduced nationally or internationally which can and do stem harmful impacts. This includes, for example, measures in connection with ballast water and invasive species spread, with oil spill responses, and others. However, progress is insufficient and, mostly, human exploitation of the areas and habitats is generally unsustainable. A couple of particularly important warnings emerge very clearly from the chapters in this series. First, there are many areas in the world where there is still minimal environmental science carried out along their coasts and in shallow habitats. Inevitably, these are commonly in regions and countries where the local population is the most directly and immediately dependent on the ocean and its food or shoreline protection. In other words, the places needing greatest conservation measures are those where impacts are greatest, where populations are rising fastest and so where the resources are being depleted fastest. Many of the most pressing problems that were summarized so well by many authors 20 years ago still exist, from unsustainable fishing to degradation of the habitats. The question must be asked: is there really no way to change this sad state of affairs, given that most of the problems described and analyzed here sometimes have been known for decades? The second warning comes from Volume 3. This contains up-to-date reviews that take a global view of some of the world's major, and best recognized, shallow marine habitats, as well as of several major global stressors, both well-established kinds and several newer ones. It might be noticed that global climate change is not dealt with individually in any of the chapters, but the reason is simple: so important is this subject, so huge, and so pervasive are its effects, that almost every chapter in this three-volume series has sections devoted to it, making it one of the best covered issues of all. While there is no doubt that this is a preoccupying issue for today and for the next several decades, it is equally clear that others are increasing too, and that these global impacts together with a wide range of more local effects appear to be affecting habitats in several synergistic ways. In total, the story is not encouraging despite some rays of light in certain areas and systems. By and large, the science underpinning our understanding of the degradation we are causing to our life-support system is perfectly clear. It is certainly as clear as it needs to be to trigger some much more serious and effective actions. Reversal of the trends, after all, is essential to human well-being. But it is probable that any action will not come from simply carrying out more science. The summary provided here is more than enough to show to the world's decision-makers that during the next perhaps 10 or 20 years, we will pass several tipping points for many of the shallow marine habitats. Our societies depend on effective action being taken. In some cases, such as coral reefs and some polar systems, it is likely that these tipping points have already passed. The well-documented state of our seas now is a matter for communication, political action, and a whole range of sociological and even psychological interventions.