Chapter 13 Light and Photosynthesis in Seagrass Meadows
319
and Alberte, 1986; Klumpp et al., 1992). The complex biofilms produced by the growth of these organisms creates physical barriers to light absorption,
gas exchange (particularly CO 2 ) and nutrient uptake
(e.g. Sand-Jensen, 1977; Bulthuis and Woelkerling,
1983; Van Montrfrans et al., 1984), and epiphyte
accumulation has been implicated as an important
agent contributing to the decline of seagrass meadows in eutrophic waters (Hemminga and Duarte,
2000). It is now possible to measure the optical properties of intact leaf-epiphyte communities accurately
and quantify their specific effects on leaf photosynthesis (Drake et al., 2003). Epiphytes exhibit varying
degrees of chlorophyll-like absorption spectra, preferentially absorbing blue and red light. The resulting
spectral bias imposed on the light actually reaching the seagrass leaf produced a two-fold greater reduction in leaf photosynthesis calculated from PUR
relative to similar calculations based on PAR. Important challenges, however, remain with regard to
the incorporation of leaf epiphytes into the vertically resolved model described here. In particular,
epiphytes distributions are characterized by strong
spatial gradients within and among leaves that also
show significant temporal variability (Bulthuis and
Woelkerling, 1983; Kirchman et al., 1984; T¨ ornblom
and Søndergaard, 1999). These relationships, their
seasonal variations and responses to environmental
change (eutrophication, CO 2 increase, etc.) deserve
more extensive quantification.
Acknowledgment
The concepts presented in this chapter represent the
combined efforts of numerous colleagues and
the support of several funding agencies, including
the National Science Foundation, New Energy Development Organization of Japan, Washington State
Department of Natural Resources, and the National
Estuarine Research Reserves Program, NOAA. Special recognition, however, goes to Dr. Steve Ackleson and the Environmental Optics Program, Office
of Naval Research, for leading the support of investigations into the optical properties of shallow water
environments.
References
Abal E, Loneragan N, Bowen P, Perry C, Udy J and Dennison
W (1994) Physiological and morphological responses of the
seagrass Zostera capricorni Aschers. to light intensity. J Exp
Mar Biol Ecol 178: 113–129
Alpine AE and Cloern JE (1988) Phytoplankton growth rates in a
light-limited environment, San Francisco Bay. Mar Ecol Prog
Ser 44: 167–173
Armstrong R (1993) Remote sensing of submerged vegetation
canopies for biomass estimation. Int J Rem Sens 14: 621–627
Batiuk R, Orth R, Moore K, Dennison W, Stevenson J, Staver L,
Carter V, Rybicki N, Hickman R, Kollar S, Bieber S, Heasley P
(1992). Chesapeake Bay Submerged Aquatic Vegetation Habitat Requirements and Restoration Targets: A Technical Synthesis. U.S. Environmental Protection Agency
Beer S and Rehnberg J (1997) The acquisition of inorganic carbon by the seagrass Zostera marina. Aquat Bot 56: 277–283
Beer S and Waisel Y (1979) Some photosynthetic carbon fixation
properties in seagrasses. Aquat Bot 7: 129–138
Berry H, Sewell A, Wyllie-Echeverria S, Reeves B, Mumford
T, Skalski J, Zimmerman R, Archer J (2003) Puget Sound
Submerged Vegetation Monitoring Project: 2000–2003 Monitoring Report, p. 57. Nearshore Habitat Program, Washington
State Department of Natural Resources
Broge N and Leblanc E (2000) Comparing prediction power and
stability of broadband and hyperspectral vegetation indices for
estimation of green leaf areas indices and canopy chlorophyll
density. Remote Sens Environ 76: 156–172
Bulthuis D and Woelkerling W (1983) Biomass accumulation
and shading effects of epiphytes on leaves of the seagrass,
Heterozostera tasmanica, in Victoria, Australia. Aquat Bot
16: 137–148
Burd A and Dunton K (2001) Field verification of a light-driven
model of biomass changes in the seagrass Halodule wrightii.
Mar Ecol Prog Ser 209: 85–98
Chauvaud S, Bouchon C and Mani´ ere (2001) Cartographie
de bioc´ eoses marines de Guadeloupe `
a partir de donn´ ees
SPOT (r´ ecifs coralliens, phan´ erogames marines, mangroves).
Oceanol Acta 24: S3–S16
Cummings M and Zimmerman R (2003) Light harvesting and
the package effect in Thalassia testudinum Koenig and Zostera
marina L.: Optical constraints on photoacclimation. Aquat Bot
75: 261–274
Dennison WC and Alberte RS (1982). Photosynthetic respones
of Zostera marina L. (eelgrass) to in situ manipulations of
light intensity. Oecologia 55: 137–144
Dennison WC and Alberte RS (1985) Role of daily light period
in the depth distribution of Zostera marina (eelgrass). Mar
Ecol Prog Ser 25: 51–61
Dennison W, Orth R, Moore K, Stevenson J, Carter V,
Kollar S, Bergstrom P, Batiuk R (1993) Assessing water quality with submersed aquatic vegetation. Habitat requirements
as barometers of Chesapeake Bay health. BioScience 43: 86–
94
Dierssen H, Zimmerman R, Leathers R, Downes T and Davis C
(2003) Remote sensing of seagrass and bathymetry in the Bahamas banks using high resolution airborne imagery. Limnol
Oceangr 48: 444–455
Drake L, Dobbs F and Zimmerman R (2003) Effects of epiphyte
load on optical properties and photosynthetic potential of the
seagrasses Thalassia testudinum Koenig and Zostera marina
L. Limnol Oceanogr 48: 456–463
Duarte C (1991a) Allometric scaling of seagrass form and productivity. Mar Ecol Prog Ser 77: 289–300
319
and Alberte, 1986; Klumpp et al., 1992). The complex biofilms produced by the growth of these organisms creates physical barriers to light absorption,
gas exchange (particularly CO 2 ) and nutrient uptake
(e.g. Sand-Jensen, 1977; Bulthuis and Woelkerling,
1983; Van Montrfrans et al., 1984), and epiphyte
accumulation has been implicated as an important
agent contributing to the decline of seagrass meadows in eutrophic waters (Hemminga and Duarte,
2000). It is now possible to measure the optical properties of intact leaf-epiphyte communities accurately
and quantify their specific effects on leaf photosynthesis (Drake et al., 2003). Epiphytes exhibit varying
degrees of chlorophyll-like absorption spectra, preferentially absorbing blue and red light. The resulting
spectral bias imposed on the light actually reaching the seagrass leaf produced a two-fold greater reduction in leaf photosynthesis calculated from PUR
relative to similar calculations based on PAR. Important challenges, however, remain with regard to
the incorporation of leaf epiphytes into the vertically resolved model described here. In particular,
epiphytes distributions are characterized by strong
spatial gradients within and among leaves that also
show significant temporal variability (Bulthuis and
Woelkerling, 1983; Kirchman et al., 1984; T¨ ornblom
and Søndergaard, 1999). These relationships, their
seasonal variations and responses to environmental
change (eutrophication, CO 2 increase, etc.) deserve
more extensive quantification.
Acknowledgment
The concepts presented in this chapter represent the
combined efforts of numerous colleagues and
the support of several funding agencies, including
the National Science Foundation, New Energy Development Organization of Japan, Washington State
Department of Natural Resources, and the National
Estuarine Research Reserves Program, NOAA. Special recognition, however, goes to Dr. Steve Ackleson and the Environmental Optics Program, Office
of Naval Research, for leading the support of investigations into the optical properties of shallow water
environments.
References
Abal E, Loneragan N, Bowen P, Perry C, Udy J and Dennison
W (1994) Physiological and morphological responses of the
seagrass Zostera capricorni Aschers. to light intensity. J Exp
Mar Biol Ecol 178: 113–129
Alpine AE and Cloern JE (1988) Phytoplankton growth rates in a
light-limited environment, San Francisco Bay. Mar Ecol Prog
Ser 44: 167–173
Armstrong R (1993) Remote sensing of submerged vegetation
canopies for biomass estimation. Int J Rem Sens 14: 621–627
Batiuk R, Orth R, Moore K, Dennison W, Stevenson J, Staver L,
Carter V, Rybicki N, Hickman R, Kollar S, Bieber S, Heasley P
(1992). Chesapeake Bay Submerged Aquatic Vegetation Habitat Requirements and Restoration Targets: A Technical Synthesis. U.S. Environmental Protection Agency
Beer S and Rehnberg J (1997) The acquisition of inorganic carbon by the seagrass Zostera marina. Aquat Bot 56: 277–283
Beer S and Waisel Y (1979) Some photosynthetic carbon fixation
properties in seagrasses. Aquat Bot 7: 129–138
Berry H, Sewell A, Wyllie-Echeverria S, Reeves B, Mumford
T, Skalski J, Zimmerman R, Archer J (2003) Puget Sound
Submerged Vegetation Monitoring Project: 2000–2003 Monitoring Report, p. 57. Nearshore Habitat Program, Washington
State Department of Natural Resources
Broge N and Leblanc E (2000) Comparing prediction power and
stability of broadband and hyperspectral vegetation indices for
estimation of green leaf areas indices and canopy chlorophyll
density. Remote Sens Environ 76: 156–172
Bulthuis D and Woelkerling W (1983) Biomass accumulation
and shading effects of epiphytes on leaves of the seagrass,
Heterozostera tasmanica, in Victoria, Australia. Aquat Bot
16: 137–148
Burd A and Dunton K (2001) Field verification of a light-driven
model of biomass changes in the seagrass Halodule wrightii.
Mar Ecol Prog Ser 209: 85–98
Chauvaud S, Bouchon C and Mani´ ere (2001) Cartographie
de bioc´ eoses marines de Guadeloupe `
a partir de donn´ ees
SPOT (r´ ecifs coralliens, phan´ erogames marines, mangroves).
Oceanol Acta 24: S3–S16
Cummings M and Zimmerman R (2003) Light harvesting and
the package effect in Thalassia testudinum Koenig and Zostera
marina L.: Optical constraints on photoacclimation. Aquat Bot
75: 261–274
Dennison WC and Alberte RS (1982). Photosynthetic respones
of Zostera marina L. (eelgrass) to in situ manipulations of
light intensity. Oecologia 55: 137–144
Dennison WC and Alberte RS (1985) Role of daily light period
in the depth distribution of Zostera marina (eelgrass). Mar
Ecol Prog Ser 25: 51–61
Dennison W, Orth R, Moore K, Stevenson J, Carter V,
Kollar S, Bergstrom P, Batiuk R (1993) Assessing water quality with submersed aquatic vegetation. Habitat requirements
as barometers of Chesapeake Bay health. BioScience 43: 86–
94
Dierssen H, Zimmerman R, Leathers R, Downes T and Davis C
(2003) Remote sensing of seagrass and bathymetry in the Bahamas banks using high resolution airborne imagery. Limnol
Oceangr 48: 444–455
Drake L, Dobbs F and Zimmerman R (2003) Effects of epiphyte
load on optical properties and photosynthetic potential of the
seagrasses Thalassia testudinum Koenig and Zostera marina
L. Limnol Oceanogr 48: 456–463
Duarte C (1991a) Allometric scaling of seagrass form and productivity. Mar Ecol Prog Ser 77: 289–300