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Relationship between Microcystis blooms

Relationship between Microcystis blooms and crustacean zooplankton in the subtropical lake in China. Feizhou Chen. Nanjing Institute of Geography and Limnology, CAS. Cyanobacteria (i.e. Microcystis aeruginosa ) blooms are frequently associated with changes of zooplankton

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Relationship between Microcystis blooms

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  1. Relationship between Microcystis blooms and crustacean zooplankton in the subtropical lake inChina Feizhou Chen Nanjing Institute of Geography and Limnology, CAS

  2. Cyanobacteria (i.e. Microcystis aeruginosa) blooms are • frequently associated with changes of zooplankton • community. • Few zooplankton can use bloom-forming cyanobacteria • directly because of its poor nutrition (Arnold 1971), • inedibility (Webster & Peters 1978) and toxin • production (Lampent 1982, Fulton & Paerl 1987). Some • zooplankton can use decomposed cyanobacteria. Some feed • other edible algae with less inhibition of bloom.

  3. Some species have certain physiological and behavioral • adaptations to coexist with cyanobacteria bloom in natural • lakes (DeMott et al. 1991) which to some extent showed • difference with the results of experiments in the laboratory.

  4. Crustacean plankton Planktivorous Fish Competition Crustacean Plankton Colonial Microcystis Population Behavior Predation

  5. Laboratory experiments • (Enclosure experiments) • Field investigations

  6. ◇ Population Toxicity (unicellar and destroyed colony) Survival rate (%) +green alga +green alga Daphnia carinata

  7. 1 ×105S 1 ×104S 1 ×105S+1 ×104M 1 ×104S+1 ×104M 1 ×105S+5 ×104M 1 ×104S+5 ×104M 1 ×105M+1 ×104S 1 ×104M+1 ×104S 1 ×105M+1 ×105S 1 ×104M+1 ×105S

  8. Mixture (colony+green alga) 1 mg/l Scenedesmus Growth rate (ind.d-1) Biomass of colonial Microcystis (mg L-1) (60-112μm)

  9. 50 mg/l Microcystis Growth rate (ind.d-1) Biomass of Scenedesmus (mg L-1)

  10. brood size (enclosure experiment) a A b B Change in mean brood size of egg-bearing females of Moina micrura and Diaphanosoma brachyurum before and after the occurrence of Microcystis bloom. The different letters show significant difference between the two periods (M. micrura: P<0.01; D. brachyurum: P<0.05).

  11. Significnatly negative correlations were shown between the biomass of Microcystis and densities of the herbivorous cladocerans during the bloom period. (Enclosure experiment)

  12. ◇ Predation Mean feeding rate Biomass of Microcystis （mg L-1） C. cornuta: FR=2.28-0.00140B, r=0.9254, p<0.05 D. carinata: FR= 1.17-0.00657B, r=0.9657, p<0.01

  13. ◇ Competition 50 mg/L colonial Microcystis +1 mg/L Scenedesmus 10 mg/L colonial Microcystis +1 mg/L Scenedesmus

  14. 50 mg/L colonial Microcystis +1 mg/L Scenedesmus 10 mg/L colonial Microcystis +1 mg/L Scenedesmus

  15. ◇ Lake Taihu Microcystis

  16. 2004-2005 Microcystis 2004-2005 in Meiliang Bay

  17. Density of crustacean plankton (ind./l) Biomass of crustacean plankton (μg/l) Microcystis density （×106 cells/L）

  18. 1997-2005 ◇ Metazoan zooplankton Dominant: Rotifera: Polyathra trigla、Rotaria rotatoria、Brachionus angularis Brachionus calyciflorus、Keratella cochlearis、Keratella quadrata、 Filinia spp.、Trichocera spp. Cladocera: Daphina spp. Ceriodaphima cornuta、Moina spp.、Bosmina spp.、Diaphanosoma brachyurum Copepoda: Sinocalanus dorrii、Limnothora sinensis、Schmackeria imopinus、Cyclops vicinus、Microcyclops spp.、Mesocyclops spp.、Thermocyclops spp.

  19. 8 1 2 6 7 3 4 5 • Meiliang Bay • Gonghu Bay • East shore area • East Lake Bay • Southwest area • Northwest area • Middle area • Wuli Lake

  20. 8 1 2 6 7 3 4 5 Cyanobacteria Green algae Annual average of densities of cyanobacteria and green algae in Lake Taihu (1996-2005)

  21. 8 1 2 6 7 3 4 5 Annual average of zooplankton densities in Lake Taihu (1997-2005)

  22. Thank you!

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