Chapter 11
Dynamics of Seagrass Stability and Change
Carlos M. Duarte
IMEDEA (CSIC-UIB), Instituto Mediterr ´
aneo de Estudios Avanzados,
Grupo de Oceanograf´ ıa Interdisciplinar, C/ Miquel
Marqu ´
es 21, 07190 Esporles (Mallorca), Spain
James W. Fourqurean
Department of Biological Sciences, Florida International University, Miami,
FL 331999, USA
Dorte Krause-Jensen
Department of Marine Ecology, National Environmental Research Institute,
Vejlsøvej 25, 8600 Silkeborg, Denmark
Birgit Olesen
Department of Plant Ecology, Institute of Biological Sciences, University of Aarhus,
Nordlandsvej 68, 8240 Risskov, Denmark
I. Introduction
To the casual observer, seagrass meadows often appear to be uniform landscapes with limited structure.
Belying this appearance, seagrass meadows contain
considerable structure and dynamics (cf. den Hartog,
1971). Seagrass meadows, at any one time, consist of
a nested structure of clones, possibly fragmented into
different ramets, each supporting a variable number
of shoots. Thus, although apparently rather static,
seagrass meadows are highly dynamic landscapes
maintained through the continuous recruitment of
new clones to the meadow, and the growth and the
turnover of the shoots they contain. Therefore, the intense dynamics of seagrass ecosystems results from
the combination of processes operating at various
scales, which—if balanced—maintain a rather stable ecosystem. Often, however, the various processes
responsible for meadow dynamics are either unbalAuthor for correspondence, email: carlosduarte@imedea.uib.es
anced or out of phase due to either natural causes
or anthropogenic effects. Such imbalances result in
changes in the meadows, which are sometimes readily evident, such as the case in catastrophic seagrass
declines or are so subtle as to even elude quantification, such as may be the case in the gradual decline
of slow-growing seagrass species (e.g. Marb` a et al.,
2003).
A proper understanding of these dynamics require, therefore, a basic understanding of contribution of the different relevant processes conforming
the seagrass meadow. These processes are those affecting clonal growth, from the dynamics of apical
meristems and the resultant shoots—the basic units
of seagrass meadows—to that of the patches. Sexual reproduction is the primary mechanism of patch
initiation, along with the dispersal of seagrass fragments, and the survival and growth of the patches is
under strong environmental control. These processes
and mechanisms will be discussed in this chapter to
offer an overview of the processes responsible for
the dynamics of seagrass meadows.
271–294.
A. W. D. Larkum et al. (eds.), Seagrasses: Biology, Ecology and Conservation, pp.
c
2006 Springer. Printed in the Netherlands.
Dynamics of Seagrass Stability and Change
Carlos M. Duarte
IMEDEA (CSIC-UIB), Instituto Mediterr ´
aneo de Estudios Avanzados,
Grupo de Oceanograf´ ıa Interdisciplinar, C/ Miquel
Marqu ´
es 21, 07190 Esporles (Mallorca), Spain
James W. Fourqurean
Department of Biological Sciences, Florida International University, Miami,
FL 331999, USA
Dorte Krause-Jensen
Department of Marine Ecology, National Environmental Research Institute,
Vejlsøvej 25, 8600 Silkeborg, Denmark
Birgit Olesen
Department of Plant Ecology, Institute of Biological Sciences, University of Aarhus,
Nordlandsvej 68, 8240 Risskov, Denmark
I. Introduction
To the casual observer, seagrass meadows often appear to be uniform landscapes with limited structure.
Belying this appearance, seagrass meadows contain
considerable structure and dynamics (cf. den Hartog,
1971). Seagrass meadows, at any one time, consist of
a nested structure of clones, possibly fragmented into
different ramets, each supporting a variable number
of shoots. Thus, although apparently rather static,
seagrass meadows are highly dynamic landscapes
maintained through the continuous recruitment of
new clones to the meadow, and the growth and the
turnover of the shoots they contain. Therefore, the intense dynamics of seagrass ecosystems results from
the combination of processes operating at various
scales, which—if balanced—maintain a rather stable ecosystem. Often, however, the various processes
responsible for meadow dynamics are either unbalAuthor for correspondence, email: carlosduarte@imedea.uib.es
anced or out of phase due to either natural causes
or anthropogenic effects. Such imbalances result in
changes in the meadows, which are sometimes readily evident, such as the case in catastrophic seagrass
declines or are so subtle as to even elude quantification, such as may be the case in the gradual decline
of slow-growing seagrass species (e.g. Marb` a et al.,
2003).
A proper understanding of these dynamics require, therefore, a basic understanding of contribution of the different relevant processes conforming
the seagrass meadow. These processes are those affecting clonal growth, from the dynamics of apical
meristems and the resultant shoots—the basic units
of seagrass meadows—to that of the patches. Sexual reproduction is the primary mechanism of patch
initiation, along with the dispersal of seagrass fragments, and the survival and growth of the patches is
under strong environmental control. These processes
and mechanisms will be discussed in this chapter to
offer an overview of the processes responsible for
the dynamics of seagrass meadows.
271–294.
A. W. D. Larkum et al. (eds.), Seagrasses: Biology, Ecology and Conservation, pp.
c
2006 Springer. Printed in the Netherlands.