25
chemical mass balance (Hayakari and Hanaishi
2001 ; Okumura et al. 2012 ) from eight kinds of
pigments identifi ed by HPLC. We investigated
the change in phytoplankton quantities before
and after the tsunami from the taxa-specifi c pigment or the ratio of each phytoplankton taxa.
Phytoplankton pigments can be used to determine an approximate index of phytoplankton classifi cation, so pigment concentrations were
substituted for the phytoplankton cell count data.
We investigated the change in phytoplankton diversity before and after the earthquake using nonmetric
multidimensional scaling (NMDS) and analysis of
similarities (ANOSIM) in the vegan package
(Oksanen et al. 2013 ) using R software ver. 2.13
(The R Project for Statistical Computing 2013 ).
2.3
Water Temperature
and Salinity Data Analysis
The contour fi gures of the temporal changes in
pigments, water temperature, and salinity at
Iwaisaki were made with Ocean Data View
software (Alfred Wegener Institute 2013 ).
3
Results
3.1
Pigment Concentrations
Before and After
the Earthquake
Chl a concentrations at Iwaisaki were 0.11–
4.7 µg/L before the earthquake and 0.06–2.3 µg/L
after the earthquake (Fig. 2a ). A phytoplankton
bloom was observed twice in the spring and
autumn. Although Chl a concentrations during
the spring bloom before the earthquake were
higher than those after the earthquake, a major
change in Chl a concentrations was not observed
before and after the earthquake. Fucoxanthin
(Fuco) concentration was high in spring, and peridinin (Per) concentration was high in autumn.
The vertical distribution of Chl a tended to be
greater near the surface (0–5 m depth) than that at
Fig. 1 ( a and b ) Sampling sites. ( a ) Iwaisaki, at the mouth of Kesennuma Bay near Kesennuma City, Miyagi, Prefecture.
( b ) Ofunato Bay near Ofunato City, Iwate Prefecture
Short-Term Effects of the March 11, 2011, Tsunami on Phytoplankton Assemblages…
chemical mass balance (Hayakari and Hanaishi
2001 ; Okumura et al. 2012 ) from eight kinds of
pigments identifi ed by HPLC. We investigated
the change in phytoplankton quantities before
and after the tsunami from the taxa-specifi c pigment or the ratio of each phytoplankton taxa.
Phytoplankton pigments can be used to determine an approximate index of phytoplankton classifi cation, so pigment concentrations were
substituted for the phytoplankton cell count data.
We investigated the change in phytoplankton diversity before and after the earthquake using nonmetric
multidimensional scaling (NMDS) and analysis of
similarities (ANOSIM) in the vegan package
(Oksanen et al. 2013 ) using R software ver. 2.13
(The R Project for Statistical Computing 2013 ).
2.3
Water Temperature
and Salinity Data Analysis
The contour fi gures of the temporal changes in
pigments, water temperature, and salinity at
Iwaisaki were made with Ocean Data View
software (Alfred Wegener Institute 2013 ).
3
Results
3.1
Pigment Concentrations
Before and After
the Earthquake
Chl a concentrations at Iwaisaki were 0.11–
4.7 µg/L before the earthquake and 0.06–2.3 µg/L
after the earthquake (Fig. 2a ). A phytoplankton
bloom was observed twice in the spring and
autumn. Although Chl a concentrations during
the spring bloom before the earthquake were
higher than those after the earthquake, a major
change in Chl a concentrations was not observed
before and after the earthquake. Fucoxanthin
(Fuco) concentration was high in spring, and peridinin (Per) concentration was high in autumn.
The vertical distribution of Chl a tended to be
greater near the surface (0–5 m depth) than that at
Fig. 1 ( a and b ) Sampling sites. ( a ) Iwaisaki, at the mouth of Kesennuma Bay near Kesennuma City, Miyagi, Prefecture.
( b ) Ofunato Bay near Ofunato City, Iwate Prefecture
Short-Term Effects of the March 11, 2011, Tsunami on Phytoplankton Assemblages…