Macrophytes, biomass production

Research on aquatic macrophytes as producers of biomass has been undertaken at Woods Hole Oceanographic Institution (WHOI) on the east coast and on the west coast by a group of collaborators in a joint effort known as the Marine Biomass Project. Studies at WHOI have focused on estuarine and coastal situations with some attention recently to freshwater plants. The Marine Farm Project has primarily been concerned with oceanic biomass production. 

The photo synthetic aquatic biomass comprises cyanobacteria (formerly called blue-green algae), planktonic, filamentous and macrophytic algae, and vascular macrophytes. The net productivity of the floodwater depends on the level of primary production by the photosynthetic biomass versus its consumption by grazing animals, particularly cladocerans, copepods, ostracods, insect larvae and molluscs. Their role will change as the canopy develops and at a leaf area index of about 6-7 there will be no more photosynthetically active radiation available to them. 

Kuehn, K. A., Lemke, M. J., Suberkropp, K. Wetzel, R. G. (2000). Microbial biomass and production associated with decaying leaf litter of the emergent macrophyte Juncus effusus. Limnology and Oceanography, 45, 862-70. 

The complex structure and seasonal dynamics of herbaceous macrophyte communities make it difficult to estimate their total annual contribution to floodplain lake production. Annual production estimates must incorporate the cumulative, sequential production of terrestrial, semiaquatic and aquatic plant communities and the spatial and temporal variation in their distributions. To date all measurements of macrophyte production have been made in a limited area on the central Amazon floodplain near Manaus. Only a few of these estimates have included contributions of more than one species. Junk and Piedade (1993) estimated the cumulative biomass increase of three successive macrophyte communities (terrestrial, semiaquatic, and aquatic) growing under... 

Finally, the impact of UV-B radiation on marine macrophytes has been mostly conducted on individual species and not on the whole community. The criteria to select species for experimentation/analyses have varied (a) they are key species due to their contribution to primary production, or because they create a habitat for other marine plants and invertebrates, as the seagrass Posidonia oceanica in the Mediterranean Sea [42,122], Laminaria beds in the North Sea [123], or Macrocystis on the Pacific coast of California [4], (b) they represent a high share of macroalgal biomass in the ecosystem, as Ulva in eutrophic coastal waters [124] and, (c) they are commercially important as Porphyra sp., Gelidium sequipedale, Macrocystis pyrifera or Chondrus crispus [30,38,125,126]. 

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