Primary Production by Michael L. Murphy

1. Primary Productionby Michael L. Murphy Presented by: Katy O’Donnell

2. Introduction Primary production is the basic source of energy for a system and acts as the only significant energy gateway into earth ecosystems Aquatic Primary Producers Benthic Algae Macrophytes Phytoplankton temperature streamflow herbivores Light nutrients Provide trophic support for invertebrates, fish and other animals in aquatic environments Algae Aquatic Plants Allochthonous OM

3. Benthic Algae Microscopic, unicellular algae Macroscopic Green, Blue-Green, Red algaes Diatoms Form thin layers on stream substrates Grow as filaments, sheets, or mats

4. Benthic Algae Filamentous Green Algae like Ulothrix Spring & Early Summer Green & Blue-Green Algae like Oedogonium, Pectonema, Phormidium Early Autumn Diatoms Winter

7. http://www.photomacrography.net/forum/userpix/1609_Oscillatoria_1_1.jpghttp://www.photomacrography.net/forum/userpix/1609_Oscillatoria_1_1.jpg http://www.biologie.uni-hamburg.de/b-online/library/webb/BOT311/Cyanobacteria/Cyanobacteria.htm

8. Macrophytes Angiosperms Differentiated roots, leaves, and vascular tissue Bryophytes Mosses and liverworts Four main growth habits: Emergent plants rooted below water level with aerial leaves Floating attached plants with submerged roots Floating unattached plants Rooted submerged plants More common in low-gradient streams with open canopies Growth forms, long, clumped, free flowing filaments Short filaments Mosses are perennial and take several years to accumulate Prefer more stable conditions and tend to be more abundant in fast moving streams

9. Phytoplankton aka Potamoplankton Restricted to slow moving streams and sloughs Centric diatoms Small green algae http://www.doctortee.com/dsu/tiftickjian/cse-img/botany/algae/diatom/centric-diatom http://www.pondsolutions.com/product_images/uploaded_images/pond-algae4.jpg

10. Primary Production Photon energy from the sun drives primary production The energy is captured as chemical bond energy in plant’s pigments and is used for maintenance, growth, or stored. Production is limited by: Sunlight Nutrients Grazers

11. Limitations Light! Light saturation photooxidation Compensation point food consumption > food production Nutrients Lethal factors: Temperature Turbidity Streambed scour Diffusion, not supply CO2, Silica, Nitrogen, Phosphorous N:P ratios are indicative of the limiting nutrient Low N:P = N limits High N:P = P limits Grazers Dominate during low flow Alter algal structure Enhance nutrient supply

12. Energy Flow how energy generated by primary producers is output to consumers Primary production is a source for autochthonous & allochthonous OM Algae and plants will vary seasonally, which affects energy flow pathways Excretion of DOM Grazing of living tissue Collection of autochthonous detritus Avenues of energy flow from producers

13. The Grazing Pathway Stream size and flow control abundance of grazers Relative abundance indicates their importance in a stream Spatial variation of current, light, and stream substrate can mask effects of grazing Aquatic plants and algae somewhat control the distribution, abundance, and growth of scrapers

14. The Detrital Pathway Dominantly allochthonous and primary pathway Autochthonous matter is still important Sloughing Dislodgement Scour Primary methods of export Export and retention time important Related to spiral length

15. Distribution of Primary Production Primary production changes predictably downstream

16. Watershed Use Timber harvest Livestock grazing Agriculture Urban development Affect primary production by altering: Riparian vegetation Stream flow Sediment Channel structure, etc

17. Question The author discusses limiting factors for primary production. Based on the, text, how do you suppose these factors change throughout the day? How do they change seasonally? How do changes in these factors affect organisms?