32
M. M. Dorgham
nitzschia in the northern Gulf of Mexico since the 1950s
(Parsons et al. 2002) and in the Santa Barbara Channel,
California (Anderson et al. 2006). The freshwater input to
the Chesapeake Bay caused a continuous decline in diversity
and a marked rise of centric/pennate ratios in most recent
sediments (Cooper 1995).
The ratio between dissolved organic carbon and dissolved
organic nitrogen (DOC:DON) appeared to play a role in the
change of the species composition of phytoplankton community. Shifts in species composition have been recently reported in association with the change in DOC:DON (Anderson
et al. 2002). Succession of heterotrophic and mixotrophic dinoflagellates as well as autotrophic microplankton
(Ismael 2003) and different phytoplankton groups (Ismael
and Dorgham 2003) were reported in eutrophic harbor of
Alexandria on the southeastern Mediterranean, Egypt.
Shifts in phytoplankton communities in eutrophic areas
lead to pronounced changes at higher trophic levels, while
eutrophication inhibits the production of lipids by some
fresh water diatoms that are essential for zooplankton sexual
reproduction (Kilham et al. 1997), and retards the growth of
certain species of phytoplankton that secrete heat-stable metabolites which enhance the spawning of green sea urchins
and blue mussels (Starr et al. 1990).
3.4 Eutrophication and HABs
The eutrophication resultants are the HABs, which cause
serious ecological problems in the aquatic ecosystems and
detrimental injury to living organisms. HABs are one of the
increasing frequent threats to aquatic ecosystems worldwide
resulting from eutrophication (Rabalais et al. 2009). They
can negatively affect the aquatic animals in localized areas as
well as in the whole ecosystem (Graneli and Turner 2008) by
activities such as clogging of fish gills (Graneli and Turner
2008), poisoning by toxins secretion (Kim et al. 2002), and
causing localized anoxia (Anderson et al. 2002).
A more recent increase in harmful bloom events occurred
in the southern hemisphere regions, particularly in the area
under human stress, such as blooms of the toxic dinoflagellates Alexandrium tamarense and Alexandrium catenella in
South African, Australian, Indian, and Thai coastal waters
(Hallegraeff 1993). Meanwhile, certain systems in northern
hemisphere showed pronounced symptoms of eutrophication, such as Baltic, North Sea, northern Adriatic, and western Mediterranean seas (Paerl 1997) and southeastern Mediterranean (Dorgham 2011).
Although several studies indicated no direct link between
eutrophication and HABs in estuarine and coastal waters
(Andrén 1999), others reported such linkages (e.g., Pan et al.
2001; Dorgham 2011), and numerous HABs were recorded in different eutrophic coastal areas worldwide, such as
blooms of Pfiesteria piscicida and Pfiesteria shumwayae in
the Albemarle-Pamlico and Chesapeake Bay (Marshall et al.
2006; Lewitus et al. 2008), the cyanobacterium Microcystis
aeruginosa (Marshall et al. 2005), the dinoflagellate Karena
brevis in both the coast of west Florida (Brand and Compton 2007), and the Gulf of Mexico (Walsh et al. 2006). The
mid-Atlantic region has many HAB species, their frequency
and abundance increasing with increased nutrient loading
(Anderson et al. 2008). The mid -Atlantic region has many
HAB species, their frequency and abundance increasing with
increased nutrient loading.
In the brackish part of the Baltic Sea, excessive phosphorous loading caused the increase of the bloom of toxic cyanobacteria species, Aphanizomenon flos-aquae and Nodularia spumigena (Niemi 1979).
Several of the HABs associated with eutrophication cause
human illness, similar to those reported in USA, including Narragansett Bay (Li and Smayda 2000), Florida Bay
(Glibert et al. 2004), the Texas coast (Buskey et al. 2001),
and San Francisco Bay (Lehman et al. 2005). In the northeastern USA, the harmful dinoflagellate Alexandrium fundyense
causes Paralytic Shellfish poisoning (PSP) and impacts other
food resources such as lobsters, fish, and marine mammals
(Anderson et al. 2008), while the nonmotile pelagophyte Aureococcus anophagefferens was reported to cause destructive
brown tide bloom in northeast and mid-Atlantic US estuaries
for two decades (Gobler et al. 2005). In addition, numerous
species were found to form harmful blooms in the mid-Atlantic, such as Prorocentrum minimum, A. anophagefferens,
Microcystis aeruginosa, Pfiesteria piscicida, P. shumwayae,
Karlodinium veneficum, Heterosigma akashiwo, Chattonella
subsalsa and Chattonella cf. vericulosa, and Fibrocapsa japonica (Anderson et al. 2008). The dinoflagellate Gymnodinium aureolumi caused repeated fish kills in aquaculture
systems in the Tunisian lagoons (Romdhane et al. 1998).
The harmful effect of algal blooms is not confined to the
toxic species, but algal blooms of numerous nontoxic species
can cause harm through their high biomass, forming foams
or scums on the surface water, the depletion of oxygen as
blooms decay, or the destruction of habitat for fish or shellfish by shading of submerged vegetation (Anderson et al.
2002).
Cyanobacteria that blooms as the most common harmful
algae since the beginning of the second half of the twentieth
century in numerous freshwater basins (Chorus and Bartram
1999) can cause wide varieties of nuisance or harm to the environment, such as thick hyperscum mats (Zohary and Roberts
1989), production of potent hepatotoxins and neurotoxins,
causing livestock and wildlife death (Codd et al. 1997), and
occasionally human death (Chorus and Bartram 1999).
The serious eutrophication during the 1960s and 1970s
in the Seto Inland Sea in Japan led to a dramatic increase
in red tides incidents by the Raphidophyceae, Chattonella
M. M. Dorgham
nitzschia in the northern Gulf of Mexico since the 1950s
(Parsons et al. 2002) and in the Santa Barbara Channel,
California (Anderson et al. 2006). The freshwater input to
the Chesapeake Bay caused a continuous decline in diversity
and a marked rise of centric/pennate ratios in most recent
sediments (Cooper 1995).
The ratio between dissolved organic carbon and dissolved
organic nitrogen (DOC:DON) appeared to play a role in the
change of the species composition of phytoplankton community. Shifts in species composition have been recently reported in association with the change in DOC:DON (Anderson
et al. 2002). Succession of heterotrophic and mixotrophic dinoflagellates as well as autotrophic microplankton
(Ismael 2003) and different phytoplankton groups (Ismael
and Dorgham 2003) were reported in eutrophic harbor of
Alexandria on the southeastern Mediterranean, Egypt.
Shifts in phytoplankton communities in eutrophic areas
lead to pronounced changes at higher trophic levels, while
eutrophication inhibits the production of lipids by some
fresh water diatoms that are essential for zooplankton sexual
reproduction (Kilham et al. 1997), and retards the growth of
certain species of phytoplankton that secrete heat-stable metabolites which enhance the spawning of green sea urchins
and blue mussels (Starr et al. 1990).
3.4 Eutrophication and HABs
The eutrophication resultants are the HABs, which cause
serious ecological problems in the aquatic ecosystems and
detrimental injury to living organisms. HABs are one of the
increasing frequent threats to aquatic ecosystems worldwide
resulting from eutrophication (Rabalais et al. 2009). They
can negatively affect the aquatic animals in localized areas as
well as in the whole ecosystem (Graneli and Turner 2008) by
activities such as clogging of fish gills (Graneli and Turner
2008), poisoning by toxins secretion (Kim et al. 2002), and
causing localized anoxia (Anderson et al. 2002).
A more recent increase in harmful bloom events occurred
in the southern hemisphere regions, particularly in the area
under human stress, such as blooms of the toxic dinoflagellates Alexandrium tamarense and Alexandrium catenella in
South African, Australian, Indian, and Thai coastal waters
(Hallegraeff 1993). Meanwhile, certain systems in northern
hemisphere showed pronounced symptoms of eutrophication, such as Baltic, North Sea, northern Adriatic, and western Mediterranean seas (Paerl 1997) and southeastern Mediterranean (Dorgham 2011).
Although several studies indicated no direct link between
eutrophication and HABs in estuarine and coastal waters
(Andrén 1999), others reported such linkages (e.g., Pan et al.
2001; Dorgham 2011), and numerous HABs were recorded in different eutrophic coastal areas worldwide, such as
blooms of Pfiesteria piscicida and Pfiesteria shumwayae in
the Albemarle-Pamlico and Chesapeake Bay (Marshall et al.
2006; Lewitus et al. 2008), the cyanobacterium Microcystis
aeruginosa (Marshall et al. 2005), the dinoflagellate Karena
brevis in both the coast of west Florida (Brand and Compton 2007), and the Gulf of Mexico (Walsh et al. 2006). The
mid-Atlantic region has many HAB species, their frequency
and abundance increasing with increased nutrient loading
(Anderson et al. 2008). The mid -Atlantic region has many
HAB species, their frequency and abundance increasing with
increased nutrient loading.
In the brackish part of the Baltic Sea, excessive phosphorous loading caused the increase of the bloom of toxic cyanobacteria species, Aphanizomenon flos-aquae and Nodularia spumigena (Niemi 1979).
Several of the HABs associated with eutrophication cause
human illness, similar to those reported in USA, including Narragansett Bay (Li and Smayda 2000), Florida Bay
(Glibert et al. 2004), the Texas coast (Buskey et al. 2001),
and San Francisco Bay (Lehman et al. 2005). In the northeastern USA, the harmful dinoflagellate Alexandrium fundyense
causes Paralytic Shellfish poisoning (PSP) and impacts other
food resources such as lobsters, fish, and marine mammals
(Anderson et al. 2008), while the nonmotile pelagophyte Aureococcus anophagefferens was reported to cause destructive
brown tide bloom in northeast and mid-Atlantic US estuaries
for two decades (Gobler et al. 2005). In addition, numerous
species were found to form harmful blooms in the mid-Atlantic, such as Prorocentrum minimum, A. anophagefferens,
Microcystis aeruginosa, Pfiesteria piscicida, P. shumwayae,
Karlodinium veneficum, Heterosigma akashiwo, Chattonella
subsalsa and Chattonella cf. vericulosa, and Fibrocapsa japonica (Anderson et al. 2008). The dinoflagellate Gymnodinium aureolumi caused repeated fish kills in aquaculture
systems in the Tunisian lagoons (Romdhane et al. 1998).
The harmful effect of algal blooms is not confined to the
toxic species, but algal blooms of numerous nontoxic species
can cause harm through their high biomass, forming foams
or scums on the surface water, the depletion of oxygen as
blooms decay, or the destruction of habitat for fish or shellfish by shading of submerged vegetation (Anderson et al.
2002).
Cyanobacteria that blooms as the most common harmful
algae since the beginning of the second half of the twentieth
century in numerous freshwater basins (Chorus and Bartram
1999) can cause wide varieties of nuisance or harm to the environment, such as thick hyperscum mats (Zohary and Roberts
1989), production of potent hepatotoxins and neurotoxins,
causing livestock and wildlife death (Codd et al. 1997), and
occasionally human death (Chorus and Bartram 1999).
The serious eutrophication during the 1960s and 1970s
in the Seto Inland Sea in Japan led to a dramatic increase
in red tides incidents by the Raphidophyceae, Chattonella