Exploring Synergistic Inter Linkages Among Three Ecological …
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Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) is an important example. This freshwater species presently occupies only 42% of its historical range and is
severely threatened by species invasion that has resulted in hybridization, predation,
disease, and severe inter specific competition (Gresswell 2011). The introduction of
lake trout (Salvelinus namaycush) to Yellowstone Lake in Yellowstone National Park
has triggered this problem (Wengeler et al. 2010). Now, the Yellowstone cutthroat
trout is expected to be benefitted by warmer stream temperatures caused by climate
change. But the simultaneous positive effects on the growth of the non-native species
is likely to offset such benefits through inter specific effects (Al-Chokhachy 2013).
3.3.2 Climate Change and Eutrophication
Climate change is likely to increase harmful cyanobacteria in eutrophic ecosystems
(Jöhnk et al. 2008a). This is because climatic change has been predicted to raise temperatures, enhance vertical stratification of aquatic ecosystems, and alter seasonal and
annual weather patterns; all such changes promote harmful cyanobacterial blooms in
eutrophic waters (Paerl and Huisman 2009). The stability of water column increases
under high temperature and consequently vertical turbulent mixing is reduced. This
provides competitive benefit to buoyant cyanobacteria. In fact, the direct and indirect impacts of warming, along with reduced wind speed and cloudiness, as well
as summer heat waves boost the development of harmful cyanobacterial blooms
(Jöhnk et al. 2008a). Warming can also enable productive cyanobacteria to invade
greater latitudes (Wiedner et al. 2007). As a whole, the effects of climatic change,
especially higher temperatures, greater vertical stratification and salinization, and
intensification of storms and droughts modulate the frequency, intensity, geographic
distribution and duration of cyanobacterial prevalence (Paerl et al. 2011). The role of
warming is in this regard is evident from the fact that blooms of toxic cyanobacteria
often occur in eutrophied ecosystems during warm months in temperate latitudes
(Davis et al. 2009). Another aspect is the food web because the direct impacts of
nutrients interact with the structure of food webs, which in turn are influenced by
climate (Moss et al. 2011).
Paerl and Paul (2012) studied the anthropogenic and climatic influence in freshwater and marine environments and found that these factors synergistically promote the dominance and persistence of harmful bloom-forming cyanobacteria. This
synergy alters bloom potentials in response to changes in thermal and hydrologic
regimes. However, changes in the thermal regime induced by climate, rather than
direct effects of temperature positively affects cyanobacterial dominance (Wagner
and Adrian 2009). When the aquatic environment becomes warmer the biomass of
large Daphnia also declines and its ability to control phytoplankton decreases. Consequently, algal crops increase with warming. However, cyanobacteria have high
temperature optima for growth and their resistance to grazing by small zooplanktons
increases with temperature. Hence, the proportion of this sometimes-toxic group is
likely to increase (Jöhnk et al. 2008b; Elliot 2010).
273
Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) is an important example. This freshwater species presently occupies only 42% of its historical range and is
severely threatened by species invasion that has resulted in hybridization, predation,
disease, and severe inter specific competition (Gresswell 2011). The introduction of
lake trout (Salvelinus namaycush) to Yellowstone Lake in Yellowstone National Park
has triggered this problem (Wengeler et al. 2010). Now, the Yellowstone cutthroat
trout is expected to be benefitted by warmer stream temperatures caused by climate
change. But the simultaneous positive effects on the growth of the non-native species
is likely to offset such benefits through inter specific effects (Al-Chokhachy 2013).
3.3.2 Climate Change and Eutrophication
Climate change is likely to increase harmful cyanobacteria in eutrophic ecosystems
(Jöhnk et al. 2008a). This is because climatic change has been predicted to raise temperatures, enhance vertical stratification of aquatic ecosystems, and alter seasonal and
annual weather patterns; all such changes promote harmful cyanobacterial blooms in
eutrophic waters (Paerl and Huisman 2009). The stability of water column increases
under high temperature and consequently vertical turbulent mixing is reduced. This
provides competitive benefit to buoyant cyanobacteria. In fact, the direct and indirect impacts of warming, along with reduced wind speed and cloudiness, as well
as summer heat waves boost the development of harmful cyanobacterial blooms
(Jöhnk et al. 2008a). Warming can also enable productive cyanobacteria to invade
greater latitudes (Wiedner et al. 2007). As a whole, the effects of climatic change,
especially higher temperatures, greater vertical stratification and salinization, and
intensification of storms and droughts modulate the frequency, intensity, geographic
distribution and duration of cyanobacterial prevalence (Paerl et al. 2011). The role of
warming is in this regard is evident from the fact that blooms of toxic cyanobacteria
often occur in eutrophied ecosystems during warm months in temperate latitudes
(Davis et al. 2009). Another aspect is the food web because the direct impacts of
nutrients interact with the structure of food webs, which in turn are influenced by
climate (Moss et al. 2011).
Paerl and Paul (2012) studied the anthropogenic and climatic influence in freshwater and marine environments and found that these factors synergistically promote the dominance and persistence of harmful bloom-forming cyanobacteria. This
synergy alters bloom potentials in response to changes in thermal and hydrologic
regimes. However, changes in the thermal regime induced by climate, rather than
direct effects of temperature positively affects cyanobacterial dominance (Wagner
and Adrian 2009). When the aquatic environment becomes warmer the biomass of
large Daphnia also declines and its ability to control phytoplankton decreases. Consequently, algal crops increase with warming. However, cyanobacteria have high
temperature optima for growth and their resistance to grazing by small zooplanktons
increases with temperature. Hence, the proportion of this sometimes-toxic group is
likely to increase (Jöhnk et al. 2008b; Elliot 2010).