Environmental Engineering Reference
In-Depth Information
(Allakhverdiev and Murata
2008
; Pfenning
1978
; Öquist et al.
1995
). However, the
anti-oxidant systems in cyanobacteria are significantly different from those of higher
plants (Asada
2006
; Demmig-Adams and Adams III
1992
,
2002
). This can vary the
effects of various environmental stresses on cyanobacteria, bacteria and higher plants.
Studies show that terrestrial plants are adapted to their annual life cycles of
growth, reproduction and senescence. Compared to the annual climate cycle, phy-
toplankton biomass can turn over around 100 times a year as a result of fast growth
and equally fast consumption by grazers (Calbet and Landry
2004
; Behrenfeld
et al.
2006
; Winder and Cloern
2010
). It has been observed that the timing of these
life-history transitions can vary among species and among regions with variation in
temperature and sunlight intensity (Winder and Cloern
2010
; Myneni et al.
1997
;
Menzel and Fabian
1999
; Peñuelas and Filella
2001
; Jolly et al.
2005
; White et al.
2009
; Richardson et al.
2010
). Correspondingly, annual phytoplankton cycles can
differ across ecosystems, because of year to year variability and with changes in the
climate system (Winder and Cloern
2010
; Garcia-Soto and Pingree
2009
; Thackeray
et al.
2008
; Paerl and Huisman
2008
; McQuatters-Gollop et al.
2008
; Cloern and
Jassby
2008
; Winder and Schindler
2004
; Edwards and Richardson
2004
; Scheffer
1991
; Pratt
1959
). These periodic cycles can be linked with annual fluctuations of
mixing, temperature, light, precipitation and with other drivers of population vari-
ability, including human disturbance. There are also effects from periodic weather
events and strong trophic coupling between phytoplankton and their consumers
(Winder and Cloern
2010
; Smetacek
1985
; Sommer et al.
1986
; Cloern
1996
).
Cyanobacteria can control a variety of environmental stressors such as UV
light, heat, cold, drought, salinity, nitrogen starvation, photo-oxidation, anaerobio-
sis and osmotic stress, by developing a number of defence mechanisms (Fay
1992
;
Tandeau de Marsac and Houmard
1993
; Sinha and Häder
1996
). The most impor-
tant one is the production of photoprotective compounds such as mycosporine-
like amino acids (MAAs) and scytonemin (Sinha et al.
1998
,
1999a
,
b
;
2001
);
availability of enzymes such as superoxide dismutase, catalase and peroxidase
(Burton and Ingold
1984
; Canini et al.
2001
); repair of DNA damage (Sinha and
Häder
2002
) and synthesis of shock proteins (Sinha and Häder
1996
; Borbely and
Suranyi
1988
; Bhagwat and Apte
1989
).
Organisms are thus affected by several factors that could either increase or
decrease their photosynthetic and respiratory activities (Doyle et al.
2005
; Nozaki
et al.
2002
; Shimura and Ichimura
1973
; Pope
1975
; Pick and Lean
1987
; Babin et
al.
1996
; Shapiro
1997
; Hyenstrand et al.
1998
; Elser
1999
; Dokulil and Teubner
2000
; MacIntyre et al.
2000
; Xie et al.
2003
; Qu et al.
2004
; Tank et al.
2005
;
Wängberg et al.
2006
; Sobrino et al.
2008
). The key factors affecting these activi-
ties are mostly documented on the basis of the growth and development of organ-
isms. Such factors are: (i) seasonal variation in sunlight and UV radiation, which
affect photosynthesis; (ii) occurrence of CO
2
forms (dissolved CO
2
, carbonic acid,
bicarbonate, carbonate); (iii) variation in temperature; (iv) water stress (drought) and
precipitation/rainfall; (v) contents and nature of DOM and POM; (vi) nutrient avail-
ability; (vii) variation in trace metal ions; (viii) salinity or salt stress; (ix) presence of
toxic pollutants; (x) effect of size-fractionated phytoplankton; (xi) global warming.
