Identification of the Lagoon Ecosystems - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 15

Identification of the lagoons and the land/sea/waterscapes to which they belong
is a step-by-step process that involves:

1. Development and implementation of extensive and intensive research and
monitoring programs, at appropriate time and space scales, consisting of
field observations, measurements, and sampling, combined with air pho-
tography and remote sensing
2. Analysis of historical information and data
3. Identification of fauna and flora taxa and estimation of biomass, abun-
dance, distribution, and dominance, as well as the trophic niche, relation-
ship (food webs), production, and demographic structure
4. Assessment and description of the three-dimensional space distribution of
major components of the hydrogeomorphic unit (HGMU) and variability
of the lagoons (e.g., water volume, water movement, water retention time,
stratification, and water-level oscillation, bottom nature, and chemistry)
5. Identification of lagoon ecotones, boundary conditions, and external driv-
ing forces

In summary, all these steps are described in detail in various chapters of this
book. This chapter identifies the crucial need for information systems dealing with
the functioning and dynamics of lagoons in order to carry out sustainable use or
adaptative management of lagoon resources and services. The remainder of this
section provides a brief summary of information relative to lagoon function, dynam-
ics, and management for sustained use and development.

2.3.1 L E

AGOON COTONE

The ecotones, or transition zones, are the border areas between the local ecosystems.
They are elementary structural and functional units in various types of landscapes and
sea/waterscapes. The physical, chemical, and biological components of ecotones have
a linear development of tens of kilometers and usually a narrow transversal develop-
ment of a few meters or, only very rarely, of hundreds of meters. In ecotones the joint
HGMUs exhibit a marked discontinuity in at least one constituent ( see Chapter 3).
There is a very extensive literature dealing with the role of ecotone components
of lagoons. Useful conclusions that support managerial purposes are:

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• A spatio-temporal organization for biological components allows for the
understanding of mass and energy exchanges between lagoon systems and
surrounding ecosystems (e.g., agricultural, forests, urban, or marine shelf
ecosystems). In fact, lagoon ecotones modulate and establish boundary
conditions that are driving forces for the lagoon's inner structural and
functional dynamics.
• As buffers, wetlands are more sensitive to the antropogenic forces as well
as regional and global climate changes. Wetlands and, in fact, lagoon eco-
tones are habitats for many vulnerable species, a space for microevolution,
or a space for longitudinal migration.

• Due to their structural and functional features, lagoon ecotones should

receive special consideration in any strategy and management program