LECTURE 6

Question 1

What is Reid’s paradox?

Answer 1

Reid’s paradox looked at oak maturity age and dispersal rates

Question 2

Explain what happened at the end of the last ice age in the northern hemisphere.

Answer 2

North America and Europe Ecosystems

• ice sheets retreated hundreds of km in northern hemisphere
• species ranges expanded northward, following retreat of ice
• constant shifting of species associations recorded as species advance

Question 3

Explain what happened at the end of the last ice age in the southern hemisphere.

Answer 3

Southern Temperate Ecosystems

• v little land at high latitudes in south, instead of ice sheets
  
  • expansive montane glaciers that shrunk/retreated upslope
• species expanded out of microclimate refugee (local expansions)
• dominant vegetation showed rapid shifts in response to climate change

Question 4

What is the Younger Dryas?

Answer 4

The Younger Dryas is a rapid cold snap at the start of the Holocene
A return to cold conditions (esp in the northern hemisphere)
Duration of 1000 years, then conditions reversed

Question 5

What triggered the Younger Dryas?

Answer 5

Global warming > ice melting (Greenland, North America)

Water built up in Great Lakes region for years (ice dam) released all that once down St. Laurence and into norther Atlantic ocean

Freshwater mixed w sea water to shut down Gulf Stream

No heat transported north (return to colder climate)

Question 6

Describe the biological changes during the Younger Dryas.

Answer 6

Spruce disappeared in North America
Vast majority of plants survived this cold period
Species may be able to tolerate relatively short, extreme climate changes
If cold snap lasted longer, would they have gone extinct?

Question 7

What are the four major drivers of marine responses to climate change?

Answer 7

TSAC

Temperature
Sea level
Acidification
Circulation

Question 8

What is the most important factor that determines the distribution of marine organisms?

Answer 8

Temperature!

Question 9

What are benthic communities? Why are they important?

Answer 9

Benthic communities are refuges for cold water species during times of warming.

Benthic communities help to recolonize shallow waters in times of cooling.

Question 10

In the Pleistocene, describe the direction of range shifts with respect to warming and cooling.

Answer 10

Poleward range shifts with warming; equatorial shifts with cooling.

Question 11

What are foraminifera? What is its significance?

Answer 11

Foraminifera are protista. They are microscopic organisms from the open ocean.

They are important because they are a proxy for sea temperatures.

Question 12

Describe what a Foram test is.

Answer 12

Looking at the ratio of oxygen-18 to oxygen-16; indicates temperature regime under which shells were formed

Question 13

What is the cool tropics paradox?

Answer 13

Foram tests indicated that tropical oceans were cooler than predicted during the interglacial periods

Until 2001, it was believed that tropical oceans warmed less than high-latitude oceans

Resolved when Pearson et al showed this was artifact of partial dissolving of foram tests in tropical waters

Better preserved foram tests showed that tropical ocean warming was in line with higher latitudes

*Using these foram test, it indicated that the oceans were cooler in the tropics than the high latitude oceans. But that was not the case. They were in fact warmer.

Question 14

T or F: Sea levels are lower in warmer temperatures.

Answer 14

False - sea levels are higher in warmer temperatures.

This is because water expands as it warms. And land ice melts and increases sea level.

Question 15

The melting of which two locations affected the sea level?

Answer 15

Melting of Antarctica and Greenland caused an increase in sea level

Coastal lowlands were flooded because of this

Question 16

T or F: Melting of sea ice causes an increase in sea levels and has no impact on food webs.

Answer 16

Melting of sea ice does not raise sea levels (ice just displaces the water)
It does impact food webs

Question 17

With respect to sea level changes in Eastern North America, foraminifera communities changed repeatedly during ______ and _____.

Answer 17

Foraminifera communities changed repeatedly during Eocene and Pleistocene

Species disappeared and others appeared

Species composition varied greatly, even when sea levels similar (substitutions from species pool)

Question 18

With respect to sea level changes in Pacific Islands, describe the conditions with respect to inner reef and outer reef species.

Answer 18

When sea levels were too low, inner reef specialists extirpated.

When the habitat resubmverged, inner reefs recolonized.

Outer reef species persisted regardless of sea level.

Question 19

Name two ways in which oceans can influence climate and biodiversity.

Answer 19

1. Changes in thermohaline circulation

2. Changes in teleconnections

Question 20

What happens in oceans when there are changes to thermohaline circulation?

Answer 20

Nutrients accumulate in deep waters and rise to surface through upwellings

Deep water form as heavy, cold, saline waters sink (bringing carbon dioxide and oxygen with them)

Shutdown of circulation = deep waters are oxygen-deprived

Question 21

What happens in oceans when there are changes to global teleconnections?

Answer 21

Marine systems respond particularly rapidly (extirpations and range shifts)
i.e. Pacific herring, Pacific Salmon, Atlantic cod, sardines, anchovies

Question 22

What is evidence of major ocean chemistry changes?

Answer 22

Major ocean chemistry changes recorded in shells/skeletons of marine organism fossils

Question 23

What are two important aspects when looking at the effects of ocean chemistry?

Answer 23

Carbon dioxide and pH > ability to form calcium carbonate structures

Question 24

What are the types of calcium-carbonate secreting organisms?

Answer 24

1. Calcite-secreting organisms (bivalves, clams, Rugose and Tabulate corals)
2. Argonite-secreating organisms (Scleractinian corals, pteropods)

Question 25

Of the two types of calcium-carbonate secreting organisms, calcite-secreting or argonite-secreting, which is an important food source to fish like salmon, mackerel, and cod?

Answer 25

Aragonite-Secreting organisms are an important food source for salmon, mackerel and cod

Question 26

T or F: Coral reef distributions are a very reliable indicator of past climate.

Answer 26

False - coral distributions are not a reliable indicator of past climate.

Question 27

Which is a better indicator of past climate conditions: coral reef distribution or coral growth rates?

Answer 27

Coral growth rates are used to infer past climate

There is a strong correlation bt coral growth rates and global mean temperatures

How quickly these corals grow are a good indicator NOT presence/absence

Question 28

Increases in ______ and ____ reduce photosynthetic productivity of zooxanthellae.

Answer 28

Increase in salinity and turbidity reduce photosynthetic productivity of zooxanthellae.

Question 29

What is turbidity?

Answer 29

Turbidity refers to how much debris is floating in the water.

Question 30

How does an increase in turbidity affect the photosynthetic productivity of zooxanthellae?

Answer 30

If there is more debris in the water, less light can get through

Question 31

How does a storm increase turbidity?

Answer 31

Storms can increase turbidity by washing land into the water

They can also bring up benthic water

Question 32

Compare and contrast how salinity and turbidity change.

Answer 32

Salinity changes on a regional and local scale

Turbidity changes on a generally local scale

Question 33

What are reef gaps?

Answer 33

Where we don’t know what was going on; there were no reefs in fossil records

Question 34

True or False: Freshwater systems cover more of Earth’s surface than oceans.

Answer 34

False - Oceans cover most of Earth’s surface while FW systems cover less than 0.1% of Earth’s surface.

Question 35

True or false: Extinctions rates in FW are higher than on land.

Answer 35

True - Extinction rates in freshwater are 3 to 4 x higher than on land.

Question 36

FW systems exist in balance between ______ and _____.

Answer 36

FW systems exist in balance between precipitation and evaporation.

Question 37

Fossil records are from _______. Why not other FW bodies?

Answer 37

Fossil records are from lakes.

Rivers and streams lack sedimentation and fast waters can destroy fossil records.

Question 38

T or F: Microorganisms preserve much better than larger organisms.

Answer 38

True. Microorganisms preserve much better than larger organisms.

Question 39

What are laggerstatten?

Answer 39

Laggerstattten are large deposits of macrofossils.

Question 40

What can we learn from sediments?

Answer 40

Sediments are indicative of biogeochemical and biological changes
Sediments are also informative about surrounding terrestrial and marine ecosystems

Question 41

What are varves?

Answer 41

Varves are annual layers created by biological or biogeochemical processes (lake turnover) that provide a clock for climate change