1. Simulation labs for Biology 4263 I gave an introductory lab talk on Keystone Predators and Barnacles and Tides on Thursday, April 16 th. These labs are due to me by May 4, 2009. Tonight, I will discuss Limiting Nutrients and Competition, Go Fish, and Oil spills. These labs are due by May 20th. Background material covered tonight – Limiting Nutrients and Competition – Go Fish – Oil spills

2. Limiting Nutrients and Competition Algal growth is dependent on the availability of sunlight and essential nutrients including nitrogen, phosphorous, and iron This lab considers the availability of sunlight to the growth rate of hypothetical green algae and the three nutrients to green, blue, and red algae by themselves and in combinations The objective of the laboratory exercise is to explore how nutrient availability can influence competition between species of algae

3. Background Information

4. Are phytoplankton adapted to light intensity? P max is the intensity of light at which photosynthesis is maximal – optimum light intensity P max - light intensity relationship for different types of phytoplankton suggests adaptation – diatoms versus dinoflagellates

5. Diatoms reach P max at low light levels Dinoflagellate photosynthesis maximal under high light intensities

6. Nutrients: Various nutrients can be limiting and the kinetics of nutrient uptake is important Limiting nutrients include N, P, Fe, Si Nutrients enter phytoplankton cells by active transport – surface area/volume is important to phyto body size

7. Nitrogen Required for amino acids Soils on land are 0.5% N Seawater averages 0.00005% N – Surface water may have no dissolved N Nitrogen frequently limits phytoplankton in coastal oceans

8. More on nitrogen Massive amounts of N from fertilizers reach coastal oceans today and is the most important cause of eutrophication Ammonium (NH 4 ), nitrate (NO 3 ) and nitrite (NO 2 ) are possible forms

9. More on nitrogen Most phytos prefer ammonium but can use nitrate N fixation (from N 2 ) important in some locations like estuaries Inputs from many sources and nitrogen cycle is complex with many bacterial transformations

10. Other nutrients: Phosphorus (PO 4 ) – Animal excretion is a source of P Iron (Fe) – In vast areas of the open ocean (Pacific), Fe is limiting – Why iron? – The Geritol Hypothesis Silicon (Si0 2 ) – silicate limiting only in diatoms

11. Nutrient kinetics Rate of uptake depends on nutrient concentration (to a point) V (uptake rate) = V max * S / (k s + S) where S = concentration of a limiting nutrient, V max = maximum uptake rate and k s = half saturation constant (the nutrient concentration at V max /2)

12. V max

13. Go Fish: Fisheries Management Techniques Collapse of fisheries stocks : NMFS – 45% of the fish stocks whose status is known are being overfished Why do fisheries collapse ? – Overfishing – Environmental factors – climate change, change in salinity, pollution – Ecological factors – changes in predators or prey – fishing down the food web (Essay to accompany this report) Pauly Worms et al. de Musert et al. 2008 Sustainable strategies – Maximal sustainable yield (MSY) – popular but often unsuccessful – Constant effort – Adaptive methods Squonkfishery

14. Oil Spills : Population Growth Oil eating bacteria –PWS, Dr. Ralph Portier Logistic equation – simulations of population growth – Bacterial division rates – Oil (food) availability

15. Incomplete Applications Must be completed by tomorrow at 4:30 PM or can’t be registered Two people – notarized participant agreement – Millie Dave – Sumit Patel