Abstract
Growth and potential photosynthetic activity of cyanobacteria (predominantly Microcystis spp.) passed through intestine of crucian carp and koi carp were compared with those of phytoplankton taken directly from lake during a 9 day cultivation of fish faeces in algal BG-11 medium. The cyanobacteria exhibited a significant reduction of activity in both maximum optical quantum yield (Fv/Fm) (P 0.05) for all the measurement intervals. The results provide experimental evidence that Microcystis can be damaged by crucian carp and koi carp digestion. That may be a complementary method using bio-manipulation to control cyanobacterial blooms. Key words: Microcystis colonies, photosynthetic activity, crucian carp, koi carp, gut passage.
Highlights
Non-traditional bio-manipulation is widely used to control nuisance algal blooms in tropical lakes that are highly productive and hard to reduce nutrient concentrations to low levels. Chen et al (2006) discovered that silver carp could effectively ingest toxic Microcystis cells up to 84.4% of total phytoplankton, but showed fast growth in Lake Taihu
The results provide experimental evidence that Microcystis can be damaged by crucian carp and koi carp digestion
The present study is the first experimental confirmation of the ability of crucian carp and koi carp to damage the photosynthetic activity of Microcystis colonies during gut passage
Summary
Non-traditional bio-manipulation is widely used to control nuisance algal blooms in tropical lakes that are highly productive and hard to reduce nutrient concentrations to low levels. Chen et al (2006) discovered that silver carp could effectively ingest toxic Microcystis cells up to 84.4% of total phytoplankton, but showed fast growth in Lake Taihu. Chen et al (2006) discovered that silver carp could effectively ingest toxic Microcystis cells up to 84.4% of total phytoplankton, but showed fast growth in Lake Taihu. Long-term observations in Lake Donghu and Lake Qiandaohu have documented that silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) (two filter-feeding planktivorous species commonly used in water bloom formation control) can suppress Microcystis blooms efficiently (Zhang et al, 2008a). Some studies found no evidence of reversed effects when blue-green algae were controlled by stocking planktivorous fish. Those with opposite view considered that some colonial and filamentous cyanobacteria remain viable after the intestinal tract of planktivorous (herbivorous) fishes and even increase their specific photosynthetic activity (Miura and Wang, 1985). Those with opposite view considered that some colonial and filamentous cyanobacteria remain viable after the intestinal tract of planktivorous (herbivorous) fishes and even increase their specific photosynthetic activity (Miura and Wang, 1985). Kolmakov et al (2006) demonstrated
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