Spatial patterns of macroalgal abundance in relation to eutrophication |
| |
Authors: | Dorte Krause-Jensen Anne Lise Middelboe Jacob Carstensen Karsten Dahl |
| |
Institution: | 1.Department of Marine Ecology,National Environmental Research Institute,Silkeborg,Denmark;2.Department of Marine Ecology,National Environmental Research Institute,Roskilde,Denmark;3.Marine Biological Laboratory,University of Copenhagen,Helsing?r,Denmark;4.European Commission, Directorate General Joint Research Centre,Institute for Environment and Sustainability,Ispra (VA),Italy |
| |
Abstract: | Based on a large monitoring data set from Danish coastal waters we tested the hypotheses: (1) The vertical pattern of algal
abundance is regulated by exposure in shallow water and by light limitation towards deeper water, resulting in a bell-shaped
abundance curve, with peak abundance located deeper at more exposed sites, (2) in deeper water, total algal abundance and
abundance of perennial algae decrease along a eutrophication gradient while (3) abundance and relative abundance of opportunists
increase. The vertical pattern of algal abundance showed a peak at intermediate water depths which was located deeper in more
exposed areas and thus confirmed our first hypothesis. For algae growing from depths of peak abundance and deeper, the study
demonstrated that total algal abundance and abundance of perennials and opportunists at given depths decreased significantly
along a eutrophication gradient and the relationships had high explanatory power (R
2 = 0.53–0.73). These results confirmed our second hypothesis. By contrast, the relative abundance of opportunists responded solely
to salinity and was largest in the most brackish areas, in contradiction to hypothesis three. The lack of coupling between
eutrophication and relative abundance of opportunists arises because both opportunists and the entire algal community were
light limited and their ratio therefore relatively insensitive to changing water clarity. The analyses indicated that algal
abundance initially responded slowly to increasing eutrophication but showed a more marked response at TN concentrations of
35–40 μM. However, the existence of possible threshold nutrient levels demands further analyses. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|