Identification of the Lagoon Ecosystems - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 16

for both natural and human-oriented landscape management actions
and should be key sites in the monitoring for climate changes. The
ecotone component protects lagoons from anthropogenic activities in
surrounding areas. For example, where farming is intensively practiced
or urban development has occurred within the catchments area, wet-
lands provide an effective control of nutrients and other chemical
compounds or mineral particles from agricultural or urban areas. Wet-
lands are also the habitats of many efficient predators or pests that
affect crop production. Therefore, preservation, restoration, or devel-
opment of these lagoon ecotones, particularly the wetland components,
is important for dealing with pollution abatement and/or integrated pest
control. Likewise, these ecotones are the major habitats of many vul-
nerable plant and animal species. The management of ecotones should
be designed to reach biodiversity conservation objectives, since biodi-
versity is clearly indicative of conservation of NC and likely of SES
benefits ( see Chapter 8 for details).

2.3.2 HGMU S -T O

PATIO EMPORAL RGANIZATION

Chapter 6 of this topic provides strong arguments to support the need for an accurate
description of the structure and spatio-temporal organization of a lagoon's HGMU.
Such arguments are needed in order to select or develop appropriate hydrodynamic
and transport models as a part of the modeling package used for the overall description
of the structure and function dynamics (productivity and carrying capacity) of the
lagoon system. Based on data concerning water exchange between lagoons and adja-
cent seas, the Kjerfve classification system of choked, restricted, and leaky lagoons is
proposed ( see Chapter 5). Ten morphohydrometric parameters are introduced that,
when quantified for a particular lagoon, provide an in-depth understanding of inner
physical and hydrochemical heterogeneity (see Chapter 6, Section 6.3, for details).
Time series measurements of morphometric parameters as described in Chapter 7
provide information on changes in the shape and bottom relief of a lagoon HGMU
under the pressure of many external driving forces (e.g., tides, waves, floods, erosion,
or deposition). The complementary relationship between the spatio-temporal organi-
zation of a lagoon HGMU and biocoenoses must be stressed again. On the one hand,
changes in many physical and chemical variables (e.g., salinity, temperature, dissolved
oxygen, nutrient availability, depth, water renewal rate, turbulence, light availability,
and bottom structure) describe the dynamic state of HGMUs as inner driving forces
for component populations and the entire community (e.g., species composition, pop-
ulation size, distribution, cost of maintenance, and primary and secondary productiv-
ity). On the other hand, the ranges of fluctuations of those variables are usually
modulated by the activity of biological components (see Chapter 5 for details).
The physical, chemical, and biochemical processes widely involved in bio-
geochemical cycling of nutrients and chemical compounds in lagoon systems are
described in Chapters 3 and 4. These chapters focus on some of the main features
of the processes of energy and mass transfer, which are of great importance for
sustainable management.