Exploring Synergistic Inter Linkages Among Three Ecological …
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3.2.3 Impacts of Algal Blooms
Decomposition of algal blooms leads to oxygen depletion and severe negative ecological impacts including the death of fishes (Carpenter et al. 1998; Smith 1998). In
fact, as eutrophication increases, piscivorous fish and zooplankton grazers decline,
and there is an increase in foraging fish and algae (Moss et al. 2011). In fresh waters,
climate change and eutrophication are likely to reduce the diversity of macrophytes,
which in turn threatens the faunal diversity of aquatic ecosystems (Chambers et al.
2008). Eutrophication has also been linked with the emergence of wildlife diseases
through direct and indirect pathways (Johnson et al. 2007). It makes water unsuitable
for fisheries, recreation, industry, and drinking because of increased growth of undesirable algae and aquatic weeds and the oxygen shortages caused by their death and
decomposition (Khan 2014). When nutrient enrichment and eutrophication cross a
certain threshold even the physiological performance of coral individual and ecosystem functioning of coral reefs are negatively affected (D’Angelo and Wiedenmann
2014). Moreover, extensive blooms of toxic cyanobacteria on the surface of eutrophic
lakes cause widespread mortality in fish and birds, and also threaten the health threat
of cattle, pets and humans (Jöhnk et al. 2008a). Harmful algal blooms are also formed
by some other species such as Karenia brevis which have also given rise to problems like death of fish, respiratory irritation in humans and closures of shell fishing
(Henrichs et al. 2015).
3.3 Synergistic Inter Linkage of Climate Change
with the Two Problems
3.3.1 Climate Change and Aquatic Alien Invasion
Climate change increases the competitive and predatory effects of non native species
on native species (Rahel and Olden 2008). It also magnifies the impacts of invasive
species already present by enhancing the virulence of diseases, and its direct effects
on habitat quality enable invasive species to expand into new areas (Rahel et al. 2008).
This occurs because warming exerts stress on the native dwellers and facilitates the
arrival of aliens (Harris and Tyrell 2001) because stressed ecosystems are highly
vulnerable to invasions (Strayer 2010).
Climate change indirectly affects local communities by increasing the dominance
of introduced species (Cascade et al. 2010). This is understood in the context of
introduced invertebrates in which the rates of growth and recruitment are accelerated
by warming relative to the natives, leading to their greater dominance. It is in fact the
main reason due to which the establishment of nonnative ascidians in New England
very well concurs with increases in winter water temperatures (Stachowicz et al.
2002). A similar fact can be observed in the marine fouling communities of Bodega
Harbor, California, USA. In this case, introduced species have been found to be
271
3.2.3 Impacts of Algal Blooms
Decomposition of algal blooms leads to oxygen depletion and severe negative ecological impacts including the death of fishes (Carpenter et al. 1998; Smith 1998). In
fact, as eutrophication increases, piscivorous fish and zooplankton grazers decline,
and there is an increase in foraging fish and algae (Moss et al. 2011). In fresh waters,
climate change and eutrophication are likely to reduce the diversity of macrophytes,
which in turn threatens the faunal diversity of aquatic ecosystems (Chambers et al.
2008). Eutrophication has also been linked with the emergence of wildlife diseases
through direct and indirect pathways (Johnson et al. 2007). It makes water unsuitable
for fisheries, recreation, industry, and drinking because of increased growth of undesirable algae and aquatic weeds and the oxygen shortages caused by their death and
decomposition (Khan 2014). When nutrient enrichment and eutrophication cross a
certain threshold even the physiological performance of coral individual and ecosystem functioning of coral reefs are negatively affected (D’Angelo and Wiedenmann
2014). Moreover, extensive blooms of toxic cyanobacteria on the surface of eutrophic
lakes cause widespread mortality in fish and birds, and also threaten the health threat
of cattle, pets and humans (Jöhnk et al. 2008a). Harmful algal blooms are also formed
by some other species such as Karenia brevis which have also given rise to problems like death of fish, respiratory irritation in humans and closures of shell fishing
(Henrichs et al. 2015).
3.3 Synergistic Inter Linkage of Climate Change
with the Two Problems
3.3.1 Climate Change and Aquatic Alien Invasion
Climate change increases the competitive and predatory effects of non native species
on native species (Rahel and Olden 2008). It also magnifies the impacts of invasive
species already present by enhancing the virulence of diseases, and its direct effects
on habitat quality enable invasive species to expand into new areas (Rahel et al. 2008).
This occurs because warming exerts stress on the native dwellers and facilitates the
arrival of aliens (Harris and Tyrell 2001) because stressed ecosystems are highly
vulnerable to invasions (Strayer 2010).
Climate change indirectly affects local communities by increasing the dominance
of introduced species (Cascade et al. 2010). This is understood in the context of
introduced invertebrates in which the rates of growth and recruitment are accelerated
by warming relative to the natives, leading to their greater dominance. It is in fact the
main reason due to which the establishment of nonnative ascidians in New England
very well concurs with increases in winter water temperatures (Stachowicz et al.
2002). A similar fact can be observed in the marine fouling communities of Bodega
Harbor, California, USA. In this case, introduced species have been found to be