Lecture 26

S

What macromolecules need nitrogen?

Salmon & grizzly

Salmon & low/high nitrogen plant species

Salmon & tree growthReference site= control with no salmonSalmon swim up rivers and streams to lay their eggs, these are “spawning sites.” The reference sites have no salmon runs but are in ecologically similar spots. What is different between the two sites

1. There are more salmon in the reference sites.
2. The trees are bigger in the spawning sites no matter how far you go from the steams
3. The tree growth is lower in the reference sites when measured close to the streams.
4. The tree growth is the same close to the streams in both sites.
5. Salmon plant trees.

How is salmon effecting trees?

There are two common isotopes of nitrogen (they vary in number of neutrons. The amount of ¹⁵N in the ocean is higher than on land. Foliar ¹⁵N is a ratio of marine nitrogen to land nitrogen positive numbers mean more marine nitrogen. What do these data suggest?

1. The reference spruces have less nitrogen
2. The reference spruces have more nitrogen
3. The reference spruces have less marine derived nitrogen.

Salmon numbers are decreasing

Mast is eaten by deer, bear, turkey, squirrel and grouse (among others). What happened after the blight?

1. Mast production fell every year
2. Mast production varied more over the decade
3. Mast production increased
4. There was no change in mast production.

When Pisaster (sea star) was removed from tidal pools, what happened?

1. There was much rejoicing
2. Species diversity decreased
3. Species diversity increased
4. Pisaster population remained the same
5. New species stepped in to take over pisaster’s job

Keystone species

Hypothesis: Orcas are eating the ottersKuluk Bay is on an open coast (+killer whales), Clam Lagoon is protected (-killer whales). A group of investigators hypothesized that the killer whales were eating the otters. Do these data support the hypothesis?

1. Yes
2. No

We’ll come back to why orcas would do this shortly, but first…These are kelp forests – on the left is what the kelp forests of the northeastern pacific ocean looked like before the nineties

White shapes are places with no otters. Black shapes are places with otters. What is otter presence correlated with?

1. Low kelp density, high sea urchin biomass
2. High kelp density, low sea urchin biomass
3. Low kelp density, low sea urchin biomass
4. High kelp density, high sea urchin biomass

What conclusion is consistent with these data?

1. Otters are a dominant species
2. Killer whales are a keystone species
3. Kelp is a keystone species
4. Otters are a keystone species
5. Kelp is a dominant species

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1. I-III
2. II, V
3. IV, V
4. II, IV, V
5. I, II