Marine Conservation Ecology

John Roff, John Roff

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781136538377
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

This major textbook provides a broad coverage of the ecological foundations of marine conservation, including the rationale, importance and practicalities of various approaches to marine conservation and management. The scope of the book encompasses an understanding of the elements of marine biodiversity - from global to local levels - threats to marine biodiversity, and the structure and function of marine environments as related to conservation issues.

The authors describe the potential approaches, initiatives and various options for conservation, from the genetic to the species, community and ecosystem levels in marine environments. They explore methods for identifying the units of conservation, and the development of defensible frameworks for marine conservation. They describe planning of ecologically integrated conservation strategies, including decision-making on size, boundaries, numbers and connectivity of protected area networks. The book also addresses relationships between fisheries and biodiversity, novel methods for conservation planning in the coastal zone and the evaluation of conservation initiatives.

1

Introduction: Why Marine Conservation is Necessary

Significance, threats and management of the oceans and biodiversity

We set sail on this new sea because there is knowledge to be gained.

John F. Kennedy (1917–1963)

Fundamental significance of the oceans

Homo sapiens has a very biased view of planet Earth; its proper name should be Oceanus or Water. The oceans are the dominant feature of our planet, covering nearly 71 per cent of its surface. Indeed, a view of the Pacific Ocean of our ‘Earth’ from space shows hardly any land at all (Colour Plate 1a). Although most of us now live in cities, removed from direct interaction with natural environments, as a terrestrial species humans are nevertheless familiar with the ‘structures’ of the land – the physiography of its mountains and valleys and landscapes. The plants and animals of the land comprise our food and natural environments, and we also daily encounter the terrestrial ‘processes’ such as radiation from the sun, rain and winds.

We have no such inherent perceptions for the oceans. Their structures and physiography – canyons, seamounts, depths and plains – are hidden from us. The character of seawater and ocean ‘climate’, and oceanic processes including the myriad types of water motions are not appreciated. The wind waves we see as we travel the surface of the oceans are largely irrelevant to its biota. Apart from an occasional meal of fish, the plants and animals of the oceans are alien to us – indeed we would need a microscope to see the most common among them. This perceived remoteness of the oceans was probably responsible for the predominant interest in terrestrial conservation at the expense of conservation of the oceans (see Irish and Norse, 1996).

The oceans contain a unique molecular substance – water – whose anomalous properties would not be predicted from comparisons to other related compounds (see e.g. Franks, 1972). Life on Earth (hereafter ‘earth’) originated in the oceans and is only possible because of the unique physico-chemical properties of water. Together, the thermal, colligative and dielectric properties of water circumscribe both the characteristics of life on earth and its physical limits and distribution. Life on earth can exist from the summits of mountains to the depths of the oceans. With a few minor exceptions (including mercury and oils) water is the only naturally occurring liquid on earth. It is THE essential ingredient of – and for – all life as we know it. In the oceans it provides not only habitats for an enormous diversity of life forms, but also buoyancy for the largest organisms the world has ever-known – the great whales. Although they are air-breathing animals like humans, they cannot support their own mass on land.

Box 1.1 Most of the properties of the oceans depend on the properties of water itself

Property	Comparison to other liquids	Importance
Heat capacity	Highest except for NH3	Planetary thermostasis and heat transfer
Latent heat of fusion	Highest except for NH3	Thermostatic effects
Latent heat of evaporation	Highest of all liquids	Thermostasis and heat transfer
Thermal expansion	Temperature of maximum density	Controls circulation of the oceans
Surface tension	Highest of all liquids	Cell physiology and ecology
Dissolving power	Highest of all liquids	Major implications for physical and biological processes
Dielectric constant	Highest of all liquids	Enables high chemical dissociation
Transparency	Relatively high	For photosynthesis, predation
Heat conduction	Highest of all liquids	Outweighed by eddy processes

Source: Adapted from Sverdrup et al (1942)

The oceans are responsible for the regulatory control of conditions on earth, including climate in both the oceans and on land; the oceans modulate and moderate the terrestrial climate. It is no exaggeration to state that life in the oceans could continue perfectly well in the absence of any land on our planet at all. However, life on land without both the climate control and water reservoir of the oceans is unthinkable. In the South Pacific Ocean, the El Nino Southern Oscillation (ENSO) drives global climates, regionally modified by variations in other oceans such as the North Atlantic Oscillation (NAO). Sea temperatures partly determine the generation and intensity of destructive typhoons and hurricanes.

Box 1.2 Importance of the oceans

Globally, the oceans are the:

• main reservoir of water: 71 per cent of the earth's surface is covered by oceans; less than 0.5 per cent is freshwater;

• main place for organisms to live; they comprise over 99 per cent of the inhabitable volume of the ‘earth’;

• main planetary reservoir of O₂;

• possible main planetary producer of O₂ from phytoplankton;

• planetary thermal reservoir and regulator;

• medium for longitudinal heat transfer and circulation;

• major reservoir of CO₂ especially in HCO₃-, CO₃ = forms;

• habitat for enormous diversity of living organisms, from bacteria to whales;

• reservoirs of enormous resource potential, both renewable and non-renewable, oil, minerals, etc.; also, about 50 per cent of global carbon fixation occurs in the sea.

Marshall McLuhan (1962) in his seminal works first defined the concept of ‘the global village’. With the subsequent rise of environmental movements and expansion of global trade and communications, the significance of the oceans to us – a terrestrial species – has finally dawned. Human civilization has now reached a point where its actions can cause changes at the planetary level. Global issues, including climate change, rising levels of CO₂ and global warming, now dominate our environmental concerns. But it is the homeostatic effects of the oceans – their productive and regulatory capacity – that have in large part mitigated our adverse environmental effects, and prevented things from being much worse than they presently are.

The primary producers of the oceans provide about one half of our atmospheric oxygen, and the deep oceans provide a major sink for the sequestration of atmospheric CO₂. Perhaps the most frightening scenario of potential environmental disaster is the possibility that deep ocean circulation may again cease (as it has in past geological periods), but this time with ‘run-away’ global warming. In more immediate human terms, the oceans are a major source of protein from fisheries, and the major trade routes among nations. Coastal zones provide an abundance of natural resources and nursery and recruitment areas for exploited species. The list goes on!

The present state of marine systems

The oceans are in a parlous state. For centuries, the oceans were thought be immutable and immune to human activities. Fish were plentiful and the capacity for the oceans to absorb human waste was believed to be unlimited. In 1605, Hugo Grotius – a Dutch jurist – laid the foundations for the International Law of the Sea by formulating the new principle ‘Mare liberum’ that the sea was international territory and all nations were free to use it for trade. Apart from a narrow coastal fringe that could be protected by land-based cannon, the seas had become a ‘commons’ – open to all to use and abuse. Predictably, and historically, two things happened: the ‘tragedy of the commons’ (Hardin, 1968) and progressive protection of coastal seas (as exclusive economic zones (EEZs)). The commons is progressively being ‘fenced-in’, but the tragedy continues.

Although the fact that humans have the capacity for massive disturbance in marine environments has been known at least since the extinction of the Steller's sea cow in 1868, marine conservation did not become an international issue until the appeals in the 1950s and 60s by authors such as Rachel Carson (1962) and Jacques Cousteau's prolific output of books, films and television series, and organizations such as Greenpeace. As a result of these appeals and rising public awareness and concern, conservation efforts in the marine environment began in earnest with international conventions and programmes such as the London Dumping Convention, the 1973 MARPOL (International Convention for the Prevention of Pollution from Ships), the United Nations Convention on the Law of the Sea (UNCLOS) (1982) and the International Whaling Commission (1946).

However, despite these early conventions, the state of marine environments has continued to deteriorate significantly. Stocks of once globally abundant fishes such as cod, herring and tuna have in many instances become ecologically and commercially extinct. Over one million whales were harvested in a 100 year period, and only the eastern Pacific grey whale has recovered to near pre-exploitation levels. Elevated levels of pollutants are found in most marine species, even those living in the Arctic and Antarctic regions. Restaurants in California that serve tuna and certain other fish are required by law to post warnings to customers about the high levels of heavy metals in fish.

Tens of thousands of kilometres of coral reefs have bleached in recent years as a result of increased ocean temperatures, which may be aggravated by the addition of greenhouse gasses from the combustion of fossil fuels. Important breeding, feeding, mating and resting areas for migratory species have been affected by human activities. This is merely a brief summary of the continuing degradation of marine systems. Those interested in detailed accounts of the effect of human activities on marine environments should read the comprehensive works by Norse (1993), Thorne-Miller and Catena (1991) and the National Research Council (1995).

Unfortunately, as time goes by and new generations of people interact with the oceans, our human memories and expectations of the ‘natural state’ of the oceans also undergo progressive change. This generational change of perception of the state of the oceans has been captured in two memorable aphorisms from Daniel Pauly – ‘The shifting baseline syndrome’ (a term coined in 1995) and ‘Fishing down marine food webs’ (Pauly et al, 1998). The first of these sayings captures the idea that although the oceans are progressively being degraded, each human generation comes to accept the degraded state as the norm. Nevertheless, whatever we currently have is still the majority of what the oceans have (or likely ever had – see below) and merits our determined conservation efforts. The second saying reflects the reality that fisheries resources of the oceans are returning smaller and smaller organisms; smaller members of species once dominated by larger populations, and smaller species once ignored or undervalued by fishers. The changing history of our views of the oceans and especially of the history of fishing fleets have been documented by Roberts (2007). We are surely and ever more rapidly reducing the biodiversity of our oceans by reducing the number of species, having an impact on habitats and their communities, and indeed destroying whole ecosystems.

What has been done to address the problems?

Humanity's response to our deteriorating marine environment has been predictably slow, reactive and piecemeal. Delays in responding to these environmental crises are exacerbated due to the fact that most marine environments are still viewed as a global commons resource, where there is little incentive to any one nation to address these issues, as problems must be solved at an international level. Early efforts at marine conservation were based on either the management of a single overexploited species (broadly referred to as single-species management) or the focus of attention on a particular environmental threat (e.g. a type of pollutant).

The discipline termed ‘fisheries management’ was developed to address the over-exploitation of single-species fish stocks. Fisheries management was initially based on the principals of maximum sustained yield (MSY), borrowed from forest management, which led to continued unsustainable harvest rates due to an inadequate understanding of the life histories of fish stocks and causes of variability in their populations. Recently, the traditional emphasis on management of single-species fish stocks has been changed to ‘ecosystem-based management’. This has come with the realization that exploitation of single species has ecological and environmental impacts and implications well beyond the populations of the exploited species themselves, and with a renewed interest and appreciation of the structures and processes of the oceans themselves.

In nearshore areas, a similar holistic approach to management, termed ‘coastal zone management’, was initiated to try to integrate human activities with the goal of management and conservation of ecological systems. Coastal zone management reflected the realization that the abiotic and biotic components of marine systems were linked across spatial and temporal scales, and that any environmental change may have consequences throughout the food web.

More recently, another integrative approach, based on the conservation of defined spaces – marine protected areas (MPAs) – has been advocated as a way to protect the ecological functions of a community within a specified area such that the benefits of preserving an area may ‘spill over’ into adjacent areas. This book will attempt to deal with all three of these approaches to marine conservation, but with considerable bias towards the last.

How will this book address these problems?

This book is not about the litany of environmental problems in the oceans, nor is it primarily about management options and techniques. It is a book about marine biodiversity, marine conservation and ways to find solutions based on an understanding of the natural ecological hierarchies of the oceans. The purpose of this book is not to examine any one specific management construct – there are several other texts that address these topics – but to examine the various approaches to conserving marine biodiversity in light of the ecological structures and functions (processes) of marine environments. This book will provide the reader with a comprehensive canon of conservation frameworks that can be applied in all marine systems.

It is our belief that those responsible for the management and conservation of marine environments often overlook ways to conserve and manage marine environments, as they do not always fit within the traditional management systems they are familiar with. We centre this book on the conservation of marine biodiversity and its components, across the ecological hierarchy, rather than focus on any particular population, community, habitat or ecosystem. This is done because we feel that the practice of marine conservation, based on ecological principles, should be applicable from the global to the local level, and from ecosystems, through habitats and communities to individual cases of separate species and their populations.

The foundation of this book is therefore ecological in character, respecting the natural organization of the environment and biota of our planet. As Dobzhansky (1973) said of...