Biology Reference
In-Depth Information
Table 8.2
Mesograzer effects on macroalgae and macroalgal communities
Grazing effect
Selected example
No effect on macroalgal growth
At natural abundances, amphipod grazers do not reduce
growth in
Sargassum
in Australia (Poore et al.
2009
)
Reduction of macroalgal growth
Limpets limit macroalgal growth on exposed rocky intertidal
shores throughout Europe, with overall stronger grazing
effects on macroalgal abundance as well as spatial
variability in assemblages in the north than the south
(Coleman et al.
2006
)
Reduction of macroalgal
reproduction
Selective grazing of periwinkles on meristematic tissue
reduces growth and reproduction in the rockweed
Fucus
(Van Alstyne
1990
)
Removal of propagules
Mesoherbivores are effective in controlling bloom-forming
Ulva
(as
Enteromorpha
) in the Baltic Sea by grazing on
early life-stage propagules (Lotze and Worm
2000
)
Algal distribution patterns
Limpet grazing controls seaweed growth at mid-intertidal
levels in rocky shores in Spain (Arrontes et al.
2004
), but
periwinkles do not have the same effect in Sweden
(Lindegarth et al.
2001
)
Selective grazing
Selective grazing on annual seaweeds in the Baltic Sea
releases long-lived fucoids from interspecific competition
and maintains overall complex communities (Worm et al.
1999
)
Damage to macroalgal tissue
causes secondary effects
Grazing of the small gastropod
Lacuna vincta
weakens tissue
in the kelp
Nereocystis luetkeana
resulting in increased
breaking and mortality through hydrodynamics (Duggins
et al.
2001
)
Importance of herbivore diversity Higher diversity of grazers removes more algal epiphytes
from seagrasses than similar herbivore abundances of
lesser diversity, with additional indirect effects such as
increased secondary production in the system (Duffy et al.
2003
)
Diversity and productivity of rocky intertidal algal
communities is not linearly related to gastropod grazer
diversity, but different grazer species have idiosyncratic
effects (O'Connor and Crowe
2005
)
Importance of herbivore identity
Selective grazing of different species of herbivorous reef
fishes causes different impacts on the algal community,
which can also vary depending on the successional stage
of the algal community (Burkpile and Hay
2010
)
Importance of herbivore life stage
and gender
In situ feeding of male and female
Idotea
isopods on
Fucus
differs with males preferring apical portions and females
preferring the less nutritious but better protected basal
portions of the algae, likely as a risk avoidance strategy
(Jormalainen et al.
2001b
)
are dependent on many complex interactions. These include feeding rate and mode
of the dominant grazer, growth rates of the algae, competitive interactions with and
among other community members, as well as interactive effects with the physical
environment (Hawkins and Hartnoll
1983
; Coleman et al.
2006
; Jenkins et al.
2008
;
see Table
8.2
for examples for the following effects). Even if mesograzer
