|Phosphorus dynamics and limitation of fast- and slow-growing temperate seaweeds in Oslofjord, Norway|Pedersen, M.F.; Borum, J.; Fotel, F.L. (2010). Phosphorus dynamics and limitation of fast- and slow-growing temperate seaweeds in Oslofjord, Norway. Mar. Ecol. Prog. Ser. 399: 173-186. http://dx.doi.org/10.3354/meps08350
In: Marine Ecology Progress Series. Inter-Research: Oldendorf/Luhe. ISSN 0171-8630; e-ISSN 1616-1599, meer
Macroalgae; Seaweeds; Nutrient dynamics; Phosphorus; Eutrophication
|Auteurs|| || Top |
- Pedersen, M.F.
- Borum, J.
- Fotel, F.L.
During coastal eutrophication, fast-growing, ephemeral macroalgae bloom at the expense of slow-growing, perennial macroalgae. This change in community composition has been explained by a differential ability to exploit and utilize inorganic nitrogen among macroalgae with different growth strategies. However, some coastal areas are becoming phosphorus-rather than nitrogen-limited; we therefore compared phosphorus dynamics among 6 temperate species of macroalgae with different growth rates in order to test whether differences in algal P-dynamics may explain macroalgal community changes. Thin, fast-growing algae (Ulva and Ceramium) took up dissolved inorganic P (DIP) much faster than thicker, slower growing species (belonging to Fucus, Ascophyllum and Laminaria) but also had much higher P-demands per unit biomass and time. DIP concentrations in the Oslofjord were low from April through August, and fast-growing species were unable to meet their P-demand from uptake for several months during summer. Hence, Ceramium and Ulva were potentially P-limited during summer, whereas Ascophyllum and Laminaria were able to acquire sufficient external DIP to remain P-replete throughout the year, Storage of P prevented Fucus species from suffering severe P-limitation for several weeks in summer. The absolute amount of P stored within the algae per unit biomass did not differ systematically among the 6 species, but the storage capacity (i.e. the period of time for which stored P could support growth) was much larger for slower growing species since this parameter depended heavily on realized growth rate. Our results show how differences in macroalgal P-dynamics may explain the changing balance among macroalgae with different growth strategies in P-deficient coastal areas.