38
M. M. Dorgham
zooplankton (Pinto-Coelho et al. 2005). In eutrophic environments with the recurrence of cyanobacterial blooms, zooplanktonic structure tends to be composed mainly of smallsize organisms (Matsumura-Tundisi and Tundisi 2005) being
efficient consumers of detritus and bacteria (Pace 1986) and
cyanobacteria (Work and Havens 2003).
Top-down forces may affect the response of zooplankton
to eutrophication (Hulot et al. 2000). In Pampulha reservoir, the size of cladoceran crusracea was less affected by
piscivorous predation than what occurred owing to eutrophication, while biomass of nauplii and young copepodides of
cyclopoid copepods increased with increasing fish predation
and eutrophication (Pinto-Coelho et al. 2005). On the other
hand increased zooplankton abundance from 1960s to 1980s
in Lake Biwa was attributed to bottom-up effects driven by
eutrophication (Tsugeki et al. 2003). The total zooplankton
abundance showed a significant positive correlation with
total phosphorus but the phytoplankton biomass showed a
bottom-up control (Hsieh et al. 2011), which directly affects
the fish propagation (Nakazawa et al. 2010).
Change in species composition and species replacement
was among the resultant effects of eutrophication on zooplankton community. A bloom of the dinoflagellate Ceratium hirundinella in Albert Falls Dam caused the effective
replacement of Moina by Bosmina, substantial reductions in
Daphnia and Ceriodaphnia, and smaller but definite increases in abundance of calanoid copepods, as well as cyclopoid
copepods (Hart and Wragg 2009). Such conditions lead to
change in the ratio of cladoceran/calanoid and of cyclopoid/
calanoid (Hsieh et al. 2011) as the increasing lake trophic
status will favor cyclopoid over calanoid copepods and
cladocerans over calanoids (Straile and Geller 1998). This
was clearly shown in Lake Constance, on the Rhine at the
northern foot of the Alps, during the 1950s and early 1960s,
when the increase in crustacean biomass was accompanied
by the dominance of Cyclops vicinus and Daphnia galeata,
the extinction of Heterocope borealis and Diaphanosoma
brachyurum, and increased biomass of all species which did
not become extinct during eutrophication, causing a shift
from a copepod-dominated lake to a cladoceran-dominated
lake (Straile and Geller 1998). On the other hand, long-term
records demonstrated the predominance of cyclopoids than
calanoids within the copepods in eutrophic basins (Rognerud
and Kjellberg 1984).
Eutrophication plays a crucial role in the change of zooplankton community structure (Karabin et al. 1997); the
dominance shifts from macrozooplankton to microzooplankton with increasing trophic state, whereas the microzooplankton can constitute the major part of the total zooplankton biomass in eutrophic condition (Park and Marshall
1997). Tintinnids, copepod nauplii, and mesozooplankton
significantly decreased with the increase of eutrophication
(Park and Marshall 1997), while rotifers dominated the total
zooplankton biomass in highly eutrophied waters (Zhao
et al. 2007)
The effect of eutrophication on zooplankton community
is also related to their taxonomy or feeding types, whereas
herbivorous zooplankton (including rotifers and cladoceras)
showed a positive response to phytoplankton biomass, while
carnivorous and omnivorous zooplankton did not show
a clear response to changes in trophic status (Hsieh et al.
2011). This pattern was observed in the Varna Lakes—Varna
Bay with a gradient of eutrophication level, whereas Varna
Bay was scaled as highly eutrophicated zooplankton abundance sustained the lowest value in Varna Bay compared to
the Lakes, with the dominance of rotifers in both areas (Stefanova et al. 2007).
3.4.6 Effect on Fish
Mortality associated with the HABs is the most likely factor
causing changes in fish community structure. During widely
distributed scale (> 500 km
2
) of the HABs, dead fishes and
fish die-offs were reported elsewhere in the region (Richlen
et al. 2010). Similar mass mortalities of fish communities
have been associated with HABs events in both temperate
(Landsberg 2002) and tropical environments (Smith 1975;
Guzman et al. 1990). Rapid declines and changes in structure
of coral reef assemblages were recorded within the Indian
Ocean as a result of HABs (Bauman et al. 2010)
3.4.7 Effect on Foraminifera
Benthic foraminiferans have been widely used as indicators
of eutrophication in coastal marine ecosystems (McGann
et al. 2003). Off Southern California, eutrophication caused
low species diversity and high population densities of the
benthic foraminifera (Bandy et al. 1965), while in Long Island Sound (North-west Atlantic), the foraminiferan Ammonia beccarii dominated at nitrogen-rich effluent discharge
(Thomas et al. 2000). In natural nutrient enrichment, Man
O’War Cay (Belize), low species diversity of epiphytic foraminiferal communities was reported with the dominance of
the encrusting, dendritic species Cornuspiramia antillarum
living on the seagrass Thalasssia testudinum (Richardson
2006). A marked transition of foraminiferal patterns was recorded owing to the long-term development of hypoxia in
front of the Po delta (northern Adriatic Sea) (Barmawidjaja
et al. 1995).
In coral reef ecosystems, dramatic changes in the benthic
foraminiferal communities could sometime occur during
eutrophication, since the dominance of smaller opportunistic
species led to a decline of larger endosymbiont-bearing taxa
(Hallock et al. 2003). Progressive increase in the abundance
M. M. Dorgham
zooplankton (Pinto-Coelho et al. 2005). In eutrophic environments with the recurrence of cyanobacterial blooms, zooplanktonic structure tends to be composed mainly of smallsize organisms (Matsumura-Tundisi and Tundisi 2005) being
efficient consumers of detritus and bacteria (Pace 1986) and
cyanobacteria (Work and Havens 2003).
Top-down forces may affect the response of zooplankton
to eutrophication (Hulot et al. 2000). In Pampulha reservoir, the size of cladoceran crusracea was less affected by
piscivorous predation than what occurred owing to eutrophication, while biomass of nauplii and young copepodides of
cyclopoid copepods increased with increasing fish predation
and eutrophication (Pinto-Coelho et al. 2005). On the other
hand increased zooplankton abundance from 1960s to 1980s
in Lake Biwa was attributed to bottom-up effects driven by
eutrophication (Tsugeki et al. 2003). The total zooplankton
abundance showed a significant positive correlation with
total phosphorus but the phytoplankton biomass showed a
bottom-up control (Hsieh et al. 2011), which directly affects
the fish propagation (Nakazawa et al. 2010).
Change in species composition and species replacement
was among the resultant effects of eutrophication on zooplankton community. A bloom of the dinoflagellate Ceratium hirundinella in Albert Falls Dam caused the effective
replacement of Moina by Bosmina, substantial reductions in
Daphnia and Ceriodaphnia, and smaller but definite increases in abundance of calanoid copepods, as well as cyclopoid
copepods (Hart and Wragg 2009). Such conditions lead to
change in the ratio of cladoceran/calanoid and of cyclopoid/
calanoid (Hsieh et al. 2011) as the increasing lake trophic
status will favor cyclopoid over calanoid copepods and
cladocerans over calanoids (Straile and Geller 1998). This
was clearly shown in Lake Constance, on the Rhine at the
northern foot of the Alps, during the 1950s and early 1960s,
when the increase in crustacean biomass was accompanied
by the dominance of Cyclops vicinus and Daphnia galeata,
the extinction of Heterocope borealis and Diaphanosoma
brachyurum, and increased biomass of all species which did
not become extinct during eutrophication, causing a shift
from a copepod-dominated lake to a cladoceran-dominated
lake (Straile and Geller 1998). On the other hand, long-term
records demonstrated the predominance of cyclopoids than
calanoids within the copepods in eutrophic basins (Rognerud
and Kjellberg 1984).
Eutrophication plays a crucial role in the change of zooplankton community structure (Karabin et al. 1997); the
dominance shifts from macrozooplankton to microzooplankton with increasing trophic state, whereas the microzooplankton can constitute the major part of the total zooplankton biomass in eutrophic condition (Park and Marshall
1997). Tintinnids, copepod nauplii, and mesozooplankton
significantly decreased with the increase of eutrophication
(Park and Marshall 1997), while rotifers dominated the total
zooplankton biomass in highly eutrophied waters (Zhao
et al. 2007)
The effect of eutrophication on zooplankton community
is also related to their taxonomy or feeding types, whereas
herbivorous zooplankton (including rotifers and cladoceras)
showed a positive response to phytoplankton biomass, while
carnivorous and omnivorous zooplankton did not show
a clear response to changes in trophic status (Hsieh et al.
2011). This pattern was observed in the Varna Lakes—Varna
Bay with a gradient of eutrophication level, whereas Varna
Bay was scaled as highly eutrophicated zooplankton abundance sustained the lowest value in Varna Bay compared to
the Lakes, with the dominance of rotifers in both areas (Stefanova et al. 2007).
3.4.6 Effect on Fish
Mortality associated with the HABs is the most likely factor
causing changes in fish community structure. During widely
distributed scale (> 500 km
2
) of the HABs, dead fishes and
fish die-offs were reported elsewhere in the region (Richlen
et al. 2010). Similar mass mortalities of fish communities
have been associated with HABs events in both temperate
(Landsberg 2002) and tropical environments (Smith 1975;
Guzman et al. 1990). Rapid declines and changes in structure
of coral reef assemblages were recorded within the Indian
Ocean as a result of HABs (Bauman et al. 2010)
3.4.7 Effect on Foraminifera
Benthic foraminiferans have been widely used as indicators
of eutrophication in coastal marine ecosystems (McGann
et al. 2003). Off Southern California, eutrophication caused
low species diversity and high population densities of the
benthic foraminifera (Bandy et al. 1965), while in Long Island Sound (North-west Atlantic), the foraminiferan Ammonia beccarii dominated at nitrogen-rich effluent discharge
(Thomas et al. 2000). In natural nutrient enrichment, Man
O’War Cay (Belize), low species diversity of epiphytic foraminiferal communities was reported with the dominance of
the encrusting, dendritic species Cornuspiramia antillarum
living on the seagrass Thalasssia testudinum (Richardson
2006). A marked transition of foraminiferal patterns was recorded owing to the long-term development of hypoxia in
front of the Po delta (northern Adriatic Sea) (Barmawidjaja
et al. 1995).
In coral reef ecosystems, dramatic changes in the benthic
foraminiferal communities could sometime occur during
eutrophication, since the dominance of smaller opportunistic
species led to a decline of larger endosymbiont-bearing taxa
(Hallock et al. 2003). Progressive increase in the abundance