Healthy Seas & Coasts

LIFE in the sea is dominated by the interaction of chemical processes and physical forces (tides, currents and weather) as demonstrated by phenomena such as global ocean circulation. The North-East Atlantic supports potentially some of the most productive fisheries in the world. However, commercially important fish species represent only a small part of such a large marine ecosystem. All marine ecosystem components link together in a food chain, or more accurately, food web. Critical to the health of the seas around Ireland are communities of seabed organisms and free-floating plants (phytoplankton) and animals (zooplankton), which are important sources of food for fish and other marine animals such as molluscs and crustaceans. These in turn are consumed by higher-ranking predators including fish such as tunas and sharks, birds, seals, cetaceans (porpoises, dolphins and whales) and humans.

Protecting the health of marine ecosystems is fundamental to sustaining marine and coastal biodiversity, economic usefulness, and the intrinsic, cultural, recreational and aesthetic values that we hold in relation to the marine environment. But what do we mean by "healthy" seas and coasts?

The subject of what constitutes a healthy marine environment is as much a societal issue as it is a scientific one. "Health" is probably better expressed as the "overall ecological quality"[1] of a marine ecosystem. In practice, society determines the desired ecosystem state by taking into account, with the help of science, the biological community, natural geographic, hydrographic and climatic factors as well as physical and chemical conditions including those resulting from human activities. In fact, this is the starting point for the development of an ecosystem-based approach to management.

One thing is certain: there is no such thing as a pristine marine environment. Humans have been excessively interfering with marine ecosystems for too long, causing species and population extinctions and altering habitats. Clearly it is pragmatic to call for the restoration to, and maintenance of marine ecosystems at a "near-to-pristine-as-practicable" state based on identifiable reference levels of individual elements of ecological quality where the influence of human activity on the ecological system is minimal, for example:

• The historic size of a fish stock before intensive exploitation commenced.
  
  
• The historic level of mercury in estuary sediments before industrial development takes place.
  
  
• The current number of seals or seabirds in a population (no historical data).

In summary, seas and coasts are healthy when the critical ecological processes, the ecosystem interactions, and the physical, chemical and biological environment are near-to-pristine-as-practicable.

Interconnectedness

Governance and management of the marine environment must reflect the fundamental interconnectedness of the ocean, land and atmosphere — indispensable components of the Earth's ecosystem — and be responsive to the dynamic biological and physical interactions of the seas and coasts.

The land-based activities of an increasing human population have a significant impact on the health of the oceans. It is the sea-land interface (the coastal zone) where the marine environment is often under the most stress from coastal development, sewage discharge, agricultural fertiliser and effluent runoff, climate change related coastal erosion, inundation and storm damage, and so forth. Spatial planning and decision-making regarding land-based activities must take into account their effect on marine ecosystems by implementing a "mountains-to-the-sea" approach to management.

Marine and coastal area management regimes have proved unrealistic and ineffectual when based on imposed geographical limits or arbitrary administrative subdivisions such as the low-tide mark or the 200 nautical mile "outer limit" of State jurisdiction, which cut across natural ecosystem boundaries and ignore the interaction of biophysical systems. Instead, the integrated management of the impact of human influence on the marine environment must be holistic and take an ecosystem-based approach that reflects natural systems and their interconnectedness and takes into account the overall cumulative, synergistic effects — locally, regionally and globally — of all human interaction with the marine environment.

Footnotes

1. i.e. the overall structure (biodiversity) and function (processes).