Conclusions
457
scale of meadow formation (95% cover) would range from less than one
year for fast growing seagrass species up to centuries for large, slowgrowing forms. For example, the large Mediterranean seagrass Posidonia
oceanica would need 280 years, the smaller, faster-growing Cymodocea
nodosa about 6 years to re-colonize with 950/0 cover.
The few results from a rather simple model demonstrate impressively
that coastal eutrophication and its effects may have severe long-lasting
consequences, at least on rooting benthic vegetation and thus for coastal
soft-bottom ecosystems. In hard-bottom systems, time scales involved in
both the eutrophication and recovery processes are possibly different.
Duarte (1995) points out that the recovery of seaweed populations may
be considerably faster because of their greater reproduction and dispersion potential. Reproductive cells of macro algae are shed in enormous
numbers and can be transported over great distances because of their
small size.
We also know little about the extent to which other functional or
structural changes induced by nutrient loadings influence time course
and time scales of both the eutrophication and the recovery processes.
Among these other changes are secondary long-term effects associated
with eutrophication, as for example altered hydrodynamic conditions
after extinction of macrophyte communities, accumulated inorganic nutrients and organic materials in the sediments, or changed conditions for
competition.
The development of more complex models that would allow quantitative prediciton of both eutrophication and recovery processes and that
could provide measures for eutrophication control and management is a
social demand and thus a challange for future research.
References
Borum I (1987) Dynamics of epiphyton on eelgrass (Zostera marina 1.) leaves: relative
roles of algal growth, herbivory, and substratum turnover. Limnol Oceanogr 32:
986-992
Borum J, Murray L, Kemp WM (1989) Aspects of nitrogen acquisition and conservation
in eelgrass plants. Aquat Bot 35: 289-300
Cebrilm I, Duarte CM (1994) Growth-dependent herbivory in natural plant communities.
Funct Ecol 8: 518-525
Chapman ARO, Craigie IS (1977) Seasonal growth in Laminaria longicruris: relations
with dissolved inorganic nutrients and internal reserves of nitrogen. Mar BioI 40:
197-205
Duarte CM (1991) Seagrass depth limits. Aquat Bot 40: 363-377
457
scale of meadow formation (95% cover) would range from less than one
year for fast growing seagrass species up to centuries for large, slowgrowing forms. For example, the large Mediterranean seagrass Posidonia
oceanica would need 280 years, the smaller, faster-growing Cymodocea
nodosa about 6 years to re-colonize with 950/0 cover.
The few results from a rather simple model demonstrate impressively
that coastal eutrophication and its effects may have severe long-lasting
consequences, at least on rooting benthic vegetation and thus for coastal
soft-bottom ecosystems. In hard-bottom systems, time scales involved in
both the eutrophication and recovery processes are possibly different.
Duarte (1995) points out that the recovery of seaweed populations may
be considerably faster because of their greater reproduction and dispersion potential. Reproductive cells of macro algae are shed in enormous
numbers and can be transported over great distances because of their
small size.
We also know little about the extent to which other functional or
structural changes induced by nutrient loadings influence time course
and time scales of both the eutrophication and the recovery processes.
Among these other changes are secondary long-term effects associated
with eutrophication, as for example altered hydrodynamic conditions
after extinction of macrophyte communities, accumulated inorganic nutrients and organic materials in the sediments, or changed conditions for
competition.
The development of more complex models that would allow quantitative prediciton of both eutrophication and recovery processes and that
could provide measures for eutrophication control and management is a
social demand and thus a challange for future research.
References
Borum I (1987) Dynamics of epiphyton on eelgrass (Zostera marina 1.) leaves: relative
roles of algal growth, herbivory, and substratum turnover. Limnol Oceanogr 32:
986-992
Borum J, Murray L, Kemp WM (1989) Aspects of nitrogen acquisition and conservation
in eelgrass plants. Aquat Bot 35: 289-300
Cebrilm I, Duarte CM (1994) Growth-dependent herbivory in natural plant communities.
Funct Ecol 8: 518-525
Chapman ARO, Craigie IS (1977) Seasonal growth in Laminaria longicruris: relations
with dissolved inorganic nutrients and internal reserves of nitrogen. Mar BioI 40:
197-205
Duarte CM (1991) Seagrass depth limits. Aquat Bot 40: 363-377