TY - JOUR
T1 - Response of Vallisneria spinulosa (Hydrocharitaceae) to contrasting nitrogen loadings in controlled lake mesocosms
AU - Zhao, Suting
AU - Yin, Liyan
AU - Chang, Fengyi
AU - Olsen, Saara
AU - Søndergaard, Martin
AU - Jeppesen, Erik
AU - Li, Wei
N1 - Publisher Copyright:
© 2015, Springer International Publishing Switzerland.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - The role of nitrogen (N) in the shift from a macrophyte-dominated state to a phytoplankton-dominated one at high N concentrations in shallow lakes is still debated. To elucidate possible toxic and ecological effects of high N on macrophyte growth, we conducted a short-term (40 day) study of a eutrophication-tolerant macrophyte, Vallisneria spinulosa (Hydrocharitaceae), incubated in pots in a mesocosm system subjected to different N concentrations (1, 3, and 5 mg l−1). Plant leaf and root length as well as growth rate decreased significantly with increased N concentrations, but most N- and P-related physiological parameters, including the soluble protein content, nitrate reductase activity, acid phosphatase activity, and tissue N and P contents, did not differ significantly among the N treatments. Only the alkaline phosphatase activity differed, being lower at high nitrogen loading, likely due to P limitation. Epiphyton and phytoplankton biomasses increased significantly with increasing N loading. Our results including a large number of physiological tests of the macrophytes, therefore, provide supporting evidence that the loss of submerged macrophytes, like V. spinulosa, seen at high N loading in shallow lakes, can be attributed to competition with phytoplankton and epiphyton rather than to toxic effects.
AB - The role of nitrogen (N) in the shift from a macrophyte-dominated state to a phytoplankton-dominated one at high N concentrations in shallow lakes is still debated. To elucidate possible toxic and ecological effects of high N on macrophyte growth, we conducted a short-term (40 day) study of a eutrophication-tolerant macrophyte, Vallisneria spinulosa (Hydrocharitaceae), incubated in pots in a mesocosm system subjected to different N concentrations (1, 3, and 5 mg l−1). Plant leaf and root length as well as growth rate decreased significantly with increased N concentrations, but most N- and P-related physiological parameters, including the soluble protein content, nitrate reductase activity, acid phosphatase activity, and tissue N and P contents, did not differ significantly among the N treatments. Only the alkaline phosphatase activity differed, being lower at high nitrogen loading, likely due to P limitation. Epiphyton and phytoplankton biomasses increased significantly with increasing N loading. Our results including a large number of physiological tests of the macrophytes, therefore, provide supporting evidence that the loss of submerged macrophytes, like V. spinulosa, seen at high N loading in shallow lakes, can be attributed to competition with phytoplankton and epiphyton rather than to toxic effects.
KW - Epiphyton
KW - Nitrogen
KW - Physiology
KW - Phytoplankton
KW - Submerged macrophyte
UR - http://www.scopus.com/inward/record.url?scp=84952639766&partnerID=8YFLogxK
U2 - 10.1007/s10750-015-2456-1
DO - 10.1007/s10750-015-2456-1
M3 - Journal article
AN - SCOPUS:84952639766
SN - 0018-8158
VL - 766
SP - 215
EP - 223
JO - Hydrobiologia
JF - Hydrobiologia
IS - 1
ER -