27
the bottom. Salinity was 28.3–34.5 PSU (Fig. 2b ),
and average salinity was 33.5 PSU. Water temperature was 5.1–26 °C.
The average Chl a concentration in the Ofunato
Bay water column was about 1 µg/L before the
earthquake (Fig. 3 ). The average concentration of
Chl a after the earthquake was 2.59 µg/L in June
and 2.42 µg/L in July. In particular, Chl a near the
surface was about 7 µg/L. Chl a tended to be higher
after than that before the earthquake. Although
diatoms were major phytoplankton taxa during
the investigation, phytoplankton assemblages other
than diatoms, such as cryptophytes, increased near
the water surface after the earthquake.
3.2
Comparison with a Location
with Phytoplankton Diversity
Based on the NMDS plot nested in the graph, no
changes in phytoplankton assemblages were
observed at Iwaisaki before and after the earthquake (Fig. 4 ). In contrast, the plots for Ofunato
Bay showed that phytoplankton locations changed
after the earthquake from those before the earthquake. Phytoplankton diversity remained
unchanged at Iwaisaki but changed in Ofunato Bay
before and after the earthquake.
The ANOSIM statistic R and P was 0.046 and
0.004 at Iwaisaki and 0.569 and 0.001 in Ofunato
Bay, respectively (Fig. 5 ). As the ANOSIM statistic
R was near zero ( R ≤ 0), a statistically signifi cant
difference between the 2010 and 2011 groups was
not observed at Iwaisaki. As the ANOSIM statistic
R was >0, a statistically signifi cant difference
between groups was observed in Ofunato Bay.
4
Discussion
4.1
Particular Phytoplankton
at Iwaisaki, Kesennuma
Bay Mouth
Chl a concentrations (0.06–2.3 µg/L) in 2011–
2012 after the earthquake were approximately
Fig. 2 (continued)
Short-Term Effects of the March 11, 2011, Tsunami on Phytoplankton Assemblages…
the bottom. Salinity was 28.3–34.5 PSU (Fig. 2b ),
and average salinity was 33.5 PSU. Water temperature was 5.1–26 °C.
The average Chl a concentration in the Ofunato
Bay water column was about 1 µg/L before the
earthquake (Fig. 3 ). The average concentration of
Chl a after the earthquake was 2.59 µg/L in June
and 2.42 µg/L in July. In particular, Chl a near the
surface was about 7 µg/L. Chl a tended to be higher
after than that before the earthquake. Although
diatoms were major phytoplankton taxa during
the investigation, phytoplankton assemblages other
than diatoms, such as cryptophytes, increased near
the water surface after the earthquake.
3.2
Comparison with a Location
with Phytoplankton Diversity
Based on the NMDS plot nested in the graph, no
changes in phytoplankton assemblages were
observed at Iwaisaki before and after the earthquake (Fig. 4 ). In contrast, the plots for Ofunato
Bay showed that phytoplankton locations changed
after the earthquake from those before the earthquake. Phytoplankton diversity remained
unchanged at Iwaisaki but changed in Ofunato Bay
before and after the earthquake.
The ANOSIM statistic R and P was 0.046 and
0.004 at Iwaisaki and 0.569 and 0.001 in Ofunato
Bay, respectively (Fig. 5 ). As the ANOSIM statistic
R was near zero ( R ≤ 0), a statistically signifi cant
difference between the 2010 and 2011 groups was
not observed at Iwaisaki. As the ANOSIM statistic
R was >0, a statistically signifi cant difference
between groups was observed in Ofunato Bay.
4
Discussion
4.1
Particular Phytoplankton
at Iwaisaki, Kesennuma
Bay Mouth
Chl a concentrations (0.06–2.3 µg/L) in 2011–
2012 after the earthquake were approximately
Fig. 2 (continued)
Short-Term Effects of the March 11, 2011, Tsunami on Phytoplankton Assemblages…