610
W. Judson Kenworthy et al.
factor that continues to handicap our understanding
of the population biology of clonal plants in general,
and seagrasses in particular (Waycott, 2000; Duarte
et al., Chapter 11). These are research topic areas where botanists, ecologists, molecular biologists,
and modelers can interact to develop the appropriate
structure and scale of predictive seagrass population
models.
In the last decade the application of concepts
derived from the clonal biology of terrestrial
angiosperms to seagrasses has begun to advance
scientific understanding of seagrass clonal systems
(de Kroon and Groenendael, 1997; Duarte et al.,
1994; Philbrick and Les, 1996; Terrados et al., 1997;
Kenworthy and Schwartzschild, 1998, Marb` a and
Duarte, 1998). Investigations related to plant demography, including age structure of discrete cohorts and
natality and mortality rates can be used to detect
whether a population is in equilibrium, growing, or in
danger of declining (Duarte and Sand Jensen, 1990;
Duarte et al., 1994; Durako, 1994; Kenworthy and
Schwarzschild, 1998; Marb` a et al., 1996; Peterson
and Fourqurean, 2001). This should continue to be
a basic focus of research, because demography and
life history processes will form the basis of models to
predict seagrass recovery from disturbance and the
benefits of conservation and restoration (Kenworthy,
2000; Fonseca et al., 2000b; Fonseca et al., 2002b;
Fonseca et al., 2004).
2. Community and Ecosystem Level Science
Species exist in functional communities interacting
with their environment and with other species, so it is
not surprising that the preservation of intact biological communities is one of the most effective ways
of conserving overall biological diversity (Duarte,
2000; Primack, 2000). Seagrasses have co-evolved
among other coastal marine biomes and habitats
such as corals, mangroves, and marshes and the flora
and fauna in these biomes are complex and dynamic,
moving among and between the different biomes
at various life stages. The science of communities,
ecosystems and biomes is central to the conservation of biodiversity, but this is more uncertain than
targeting individual species dynamics (e.g. Bell and
Westoby, 1986). Numerous papers discuss the topic
of what constitutes a seagrass community but there
needs to be greater attention paid to understanding the physico-chemical and biological processes
which maintain the integrity of the communities and
their function and stability in the biomes (Howard
et al., 1989; Heck et al., 1995; Beck et al., 2001).
IV. Science-Based Protection Approaches
A. Overall Approach
The framework for implementing seagrass biome
conservation can be attained through the general
application of two approaches: (i) statutory authority (prescriptive) and (ii) general consensus planning (nonprescriptive), or a combination of the two
(Coles and Fortes, 2001). Research supporting any
one of these approaches or integrating studies that
support some combination of these approaches can
help managers develop tools for implementing conservation practices. Examples of the role of science in guiding the direction of these approaches
follow.
B. Science and Prescriptive Approaches
Rarely are marine scientists given the opportunity
to participate directly in writing statutes or legislation; however, indirect consultation with the scientific community as policies and programs develop
often occurs and there are numerous examples of
scientists making significant contributions to the development and implementation of laws for seagrass
protection and conservation (Stephan and Bigford,
1997; Coles and Fortes, 2001; RAC-SPA, 2000).
Even with the uncertainties associated with limited
data and rapid response times, scientists can help
managers make wise decisions without sacrificing
scientific quality. Better known as adaptive management practices, scientists are frequently called
upon to support difficult management decisions. For
example, when a species is listed as either endangered or threatened under the United States Endangered Species Act a recovery plan must be formulated that includes identification of ‘critical habitat’.
This statutory obligation requires scientific support
for the selection of sites to be designated critical
habitat. Because critical habitat provides a higher
degree of protection for a species, the designations
are often controversial. In the case of the threatened seagrass Halophila johnsonii, the first seagrass listed under the U.S. Endangered Species Act,
critical habitat selection was one of the most contentious aspects of the listing process. Even so, the
W. Judson Kenworthy et al.
factor that continues to handicap our understanding
of the population biology of clonal plants in general,
and seagrasses in particular (Waycott, 2000; Duarte
et al., Chapter 11). These are research topic areas where botanists, ecologists, molecular biologists,
and modelers can interact to develop the appropriate
structure and scale of predictive seagrass population
models.
In the last decade the application of concepts
derived from the clonal biology of terrestrial
angiosperms to seagrasses has begun to advance
scientific understanding of seagrass clonal systems
(de Kroon and Groenendael, 1997; Duarte et al.,
1994; Philbrick and Les, 1996; Terrados et al., 1997;
Kenworthy and Schwartzschild, 1998, Marb` a and
Duarte, 1998). Investigations related to plant demography, including age structure of discrete cohorts and
natality and mortality rates can be used to detect
whether a population is in equilibrium, growing, or in
danger of declining (Duarte and Sand Jensen, 1990;
Duarte et al., 1994; Durako, 1994; Kenworthy and
Schwarzschild, 1998; Marb` a et al., 1996; Peterson
and Fourqurean, 2001). This should continue to be
a basic focus of research, because demography and
life history processes will form the basis of models to
predict seagrass recovery from disturbance and the
benefits of conservation and restoration (Kenworthy,
2000; Fonseca et al., 2000b; Fonseca et al., 2002b;
Fonseca et al., 2004).
2. Community and Ecosystem Level Science
Species exist in functional communities interacting
with their environment and with other species, so it is
not surprising that the preservation of intact biological communities is one of the most effective ways
of conserving overall biological diversity (Duarte,
2000; Primack, 2000). Seagrasses have co-evolved
among other coastal marine biomes and habitats
such as corals, mangroves, and marshes and the flora
and fauna in these biomes are complex and dynamic,
moving among and between the different biomes
at various life stages. The science of communities,
ecosystems and biomes is central to the conservation of biodiversity, but this is more uncertain than
targeting individual species dynamics (e.g. Bell and
Westoby, 1986). Numerous papers discuss the topic
of what constitutes a seagrass community but there
needs to be greater attention paid to understanding the physico-chemical and biological processes
which maintain the integrity of the communities and
their function and stability in the biomes (Howard
et al., 1989; Heck et al., 1995; Beck et al., 2001).
IV. Science-Based Protection Approaches
A. Overall Approach
The framework for implementing seagrass biome
conservation can be attained through the general
application of two approaches: (i) statutory authority (prescriptive) and (ii) general consensus planning (nonprescriptive), or a combination of the two
(Coles and Fortes, 2001). Research supporting any
one of these approaches or integrating studies that
support some combination of these approaches can
help managers develop tools for implementing conservation practices. Examples of the role of science in guiding the direction of these approaches
follow.
B. Science and Prescriptive Approaches
Rarely are marine scientists given the opportunity
to participate directly in writing statutes or legislation; however, indirect consultation with the scientific community as policies and programs develop
often occurs and there are numerous examples of
scientists making significant contributions to the development and implementation of laws for seagrass
protection and conservation (Stephan and Bigford,
1997; Coles and Fortes, 2001; RAC-SPA, 2000).
Even with the uncertainties associated with limited
data and rapid response times, scientists can help
managers make wise decisions without sacrificing
scientific quality. Better known as adaptive management practices, scientists are frequently called
upon to support difficult management decisions. For
example, when a species is listed as either endangered or threatened under the United States Endangered Species Act a recovery plan must be formulated that includes identification of ‘critical habitat’.
This statutory obligation requires scientific support
for the selection of sites to be designated critical
habitat. Because critical habitat provides a higher
degree of protection for a species, the designations
are often controversial. In the case of the threatened seagrass Halophila johnsonii, the first seagrass listed under the U.S. Endangered Species Act,
critical habitat selection was one of the most contentious aspects of the listing process. Even so, the