Streams and Rivers in South America (with emphasis on algae)

1. Streams and Rivers in South America(with emphasis on algae) Morgan L. Vis Neotropical Ecology Seminar French Guiana

2. Questions to consider • What type of algae usually grow in large rivers like the Amazon? • What are macroalgae? • What are the morphological types of macroalgae? • Is the diversity of macroalgae in the eastern Atlantic Rainforest greater or less than in other areas? Why? • What is known about the seasonality of macroalgae?

3. Classification of Streams & Rivers • Based on orders • 2- 1st order streams meet to form a 2nd order stream. • 2- 2nd order streams meet to form a 3rd order etc. • When a 1st meets a 2nd it stays a 2nd.

4. Amazon River (largest in terms of drainage area)

5. The Amazon – a large flood plain river

6. Animals of the Large Rivers • Fish (~2000 species) • Mostly small • Feed on zooplankton • A few large types used as food source • Piranhas • Invertebrates

7. Animals of the Large Rivers • Alligators • Caiman • Birds • Dolphins/Manatees • Otters • Turtles • Capybara

8. Large Rivers and Algae • Turbid • Deep • Lack of substrate • Phytoplankton

9. Stream Macroalgae Usually attached to the bottom and have a discrete thallus that can be seen with the naked eye.

10. Functional Groupings • Algae that bend in the direction of the flow to reduce drag • Algae that avoid flow by living within the boundary layer

11. Gelatinous Filament Batrachospermum

12. Tuft Audouinella

13. Cladophora Free Filament

14. Phormidium Mat

15. Lemanea Tissue Like

16. Nostoc Gelatinous Colony

17. Heribauldiella Crust

18. Rio Preto • Large river system • Southeastern Brazil • Flows through temperate forests and tropic regions

19. Distribution of stream macroalgae in the eastern Atlantic Rainforest of Sao Paulo State, southeastern Brazil • 52 streams sampled • 42 macroalgal taxa collected • Most abundant • Audouinella pygmaea • Compsopogon coeruleus • Microcoleus subtorulosus • No correlations for overall macroalgae • Audouinella occurred in higher conductance & current velocity with lower pH

20. Distribution of stream macroalgae in the eastern Atlantic Rainforest of Sao Paulo State, southeastern Brazil • Lower diversity than found in other studies • Patchy distribution • Intermediate disturbance hypothesis – this region has high disturbance • High precipitation good for terrestrial plant diversity but could be lowering macroalgal diversity.

21. Seasonality of macroalgae in 3 tropical drainage basins • 3 separate but close drainage basins • Monthly sampling for 1 year • Algae & phys/chem measured • Purpose: compare dynamics of macroalgal communities and evaluate most influential variables acting on seasonality

22. Seasonality of macroalgae in 3 tropical drainage basins - Results • Several factors influence community dynamics • Percent cover – oxygen, cross-sectional area, pH, current velocity, conductance, turbidity & precipitation • Richness – oxygen, temperature, turbidity, pH and current velocity • Overall – precipitation & turbidity • Seasonal patterns the same in 3 drainage basins with high percent cover & richness in dry season (June-November?)

23. Seasonality of macroalgae in 3 tropical drainage basins • Chantransia • high Sept-Feb & April –Sept • Correlated to current velocity & conductance • Stigeoclonium • Abundant April - Sept • Various correlations in different spots • Batrachospermum • Low cover Dec-May • Various correlation • Phormidium • High Dec-April • Neg corr oxygen & current velocity

24. Microhabitat and plant structure of Batrachospermum populations in four stream • 7 Batrachospermum populations • 4 B. delicatulum • 1 B. macrosporum • 2 Chantransia • Quadrats sampled during Aug-Sept • Purpose – examine microhabitat, plant structure and the influence of physical variables

25. Microhabitat and plant structure of Batrachospermum populations in four stream

26. Microhabitat and plant structure of Batrachospermum populations in four stream • B. delicatulum - 1, 4, 5, 6 • B. macrosporum – 2 • Much higher male/female ratio in 2 • Different reproductive strategies

27. Questions revisited • What type of algae usually grow in large rivers like the Amazon? • Phytoplankton – those that can float in the water • What are macroalgae? • Algae that are visible with the naked eye • What are the morphological types of macroalgae? • Gelatinous filament, free filament, tuft, mat, tissue-like, gelatinous colony, crust • Is the diversity of macroalgae in the eastern Atlantic Rainforest greater or less than in other areas? Why? • Less – possibly due to high disturbance • What is known about the seasonality of macroalgae? • Most influenced by precip & turbidity; greatest in dry season

28. Bibliography • http://eebweb.arizona.edu/fish/calhamaz.html#anchor5050752 • http://www.netshaman.com/brazil/index.html • Giller, P.S. & Malmqvist, B. 1998. The Biology of Streams and Rivers. Oxford Press. • Branco, C.C.Z. & Necchi Jr., O. 1996. Distribution of stream macroalgae in the eastern Atlantic Rainforest of Sao Paulo State, southeastern Brazil. Hydrobiologia 333: 139-150. • Branco, L.H.Z. & Necchi Jr., O. 1997. Seasonality of macroalgae in three tropical drainage basins in Sao Paulo State, southeastern Brazil. Archiv fur Hydrobiologia 141: 75-91. • Necchi Jr., O. 1997. Microhabitat and plant structure of Batrachospermum (Batrachospermales, Rhodophyta) populations in four streams of Sao Paulo State, southeastern Brazil. Phycological Research 45: 39-45.