Transcript PowerPoint 2

Simulation labs for Biology 4263
• I gave an introductory lab talk on Keystone Predators
and Barnacles and Tides on Thursday , April 16th. 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
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
Background Information
Are phytoplankton adapted
to light intensity?
• Pmax is the intensity of light at which
photosynthesis is maximal
– optimum light intensity
• Pmax - light intensity relationship for different
types of phytoplankton suggests adaptation
– diatoms versus dinoflagellates
Diatoms reach Pmax at low light levels
Dinoflagellate photosynthesis maximal
under high light intensities
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
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
More on nitrogen
• Massive amounts of N from fertilizers
reach coastal oceans today and is the
most important cause of eutrophication
• Ammonium (NH4), nitrate (NO3) and
nitrite (NO2) are possible forms
More on nitrogen
• Most phytos prefer ammonium but
can use nitrate
• N fixation (from N2) important in some
locations like estuaries
• Inputs from many sources and
nitrogen cycle is complex with many
bacterial transformations
Other nutrients:
• Phosphorus (PO4)
– 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 (Si02)
– silicate limiting only in diatoms
Nutrient kinetics
Rate of uptake depends on nutrient
concentration (to a point)
• V (uptake rate) = Vmax * S / (ks + S) where S =
concentration of a limiting nutrient, Vmax =
maximum uptake rate and ks = half
saturation constant (the nutrient
concentration at Vmax/2)
Vmax
Go Fish: Fisheries Management Techniques
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Collapse of fisheries stocks :
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NMFS – 45% of the fish stocks whose status is known are being overfished
Why do fisheries collapse ?
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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)
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Sustainable strategies
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Pauly
Worms et al.
de Musert et al. 2008
Maximal sustainable yield (MSY) – popular but often unsuccessful
Constant effort
Adaptive methods
Squonkfishery
Oil Spills : Population Growth
• Oil eating bacteria –PWS, Dr. Ralph Portier
• Logistic equation – simulations of population
growth
– Bacterial division rates
– Oil (food) availability
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