Ch. 13 - Communities and Ecology of the Offshore Oceans
How is the North Atlantic Ocean portrayed as the "standard" cold-temperate ocean?
Contrast the compensation depth with the critical depth.
Describe seasonal patterns for a typical phytoplankter in the North Atlantic Ocean.
Light Comp. Depth Stirring Depth
What role does the thermocline have? What is it? When does it form?
Contrast the Sargasso Sea to the North Atlantic Ocean.
Contrast the North Polar Sea to the North Atlantic Ocean.
Contrast the North Polar Sea to the South Polar Ocean.
Where and why does upwelling occur?
How is net primary productivity (NPP) defined?
Contrast eutrophic and oligotrophic ocean communities. Where are they? Contrast them with the "apple index."
Where is the mesopelagic community? What are its typical organisms? How do they get their food?
Suggest alternative (not necessarily mutually exclusive) hypotheses that might account for vertical migration of mesopelagic animals.
What affect does vertical migration have on overall oceanic productivity?
Where is the bathypelagic community?What are its typical organisms? How do they get their food?
Describe some feeding and reproductive adaptations to life in this environment.
What is typical ocean bottom? What organisms are there? About how dense are they?
Where do hydrothermal vent communities occur? How do they contrast with typical ocean bottom communities?
Describe the energy flow of a hydrothermal vent community.What are some feeding adaptations of hydrothermal vent communities?
Chapter 14 – Ecology of Shallow Marine Environments
Compare the following habitats with respect to 1) physical characteristics; 2) typical communities; 3) amount of productivity; 4) source of productivity; 5) relative degree of disturbance; 6) long-term fluctuations
Sea grass communities
Review Questions for Chapter 14
Give two reasons why shallow water depths are more likely to be productive than deeper water depths (see Fig. 14.1).
Why doesn’t wind tend to directly cause upwelling of nutrients?
Why does disturbance increase species diversity? What is the stability-time hypothesis?
How did Connell distinguish between predation and competition alternative explanations for why some barnacles were most common in sub-optimal habitats?
Give an example of a community characterized by alternative stable states.
Contrast northern and southern hemisphere rocky subtidal kelp forests.
Why are sea otters considered keystone species?
Contrast sediment habitats: cobbles, sand, and mud.
What are some typical characteristics of interstitial fauna?
Why does the interstitial fauna produce more biomass each year than the macrofauna, even though the macrofauna typically outweighs the interstitial fauna?
Biol. 317 - Lecture notes – Chapter 16 (Long-term change) and 17 (Oil pollution)
New species take up residence
OR Resident species disappear completely
1. Dispersal (drift, migrate, or be carried across oceanic barriers)
2. Evolutionary change (new species arise by splitting of old species)
3. Long-term shift in environmental conditions (e.g., ice ages, cooling/warming)
unusally broad larval dispersal (e.g., El Niño changed normal current patterns)
rafting (as “benthic” juveniles or adults)
continental drift (opening of formerly isolated ocean basins)
Ship transport (often in ballast, e.g., zebra mussel)
Incidental to transport of commercial species (e.g., oysters)
Other human transport
Why don’t species always survive when transported?
unsuitable physical/chemical conditions
inferior competitive abilities
susceptable to predation
Are there generalities about those invasive species that do survive?
They come from a community with more species
They are generalists, not highly specialized
The species invades without its normal predators/parasites/competitors
There is an empty “niche”
Physical/chemical conditions are similar
Examples of non-native species on West Coast
Pacific oyster (Crassostrea gigas) – introduced from Japan
- grow more rapidly than indigenous species
- superior competitors
- but most places is unable to reproduce (with exceptions)
American lobsters – introduced from Atlantic coast
- no lobsters present in Canadian West Coast, niche appears vacant
- reproduction appeared normal
- did not survive for unknown reasons
A more successful example is described: Neries diversicolor invading Caspian Sea
- became very common without apparent impact on native species
Impact on indigenous species is hard to predict
- Sargassum muticum and Ocenebra japonica are examples of invasive
species on West Coast
- Some more damaging than others
Species tend to increase through time over evolutionary time
- See Fig. 16.4 (Figure based on recently deceased paleontologist, Jack Sepkoski)
- Whole communities suffered dramatic extinction events, generally due to
extrinsic factors, not due to being “out-competed”
- Early communities lacked deep burrowers, etc.
Read about impact of Ice Ages up to p. 388!
Ch. 17 – Additions of Materials to the Oceans
Additional review questions:
What are the sources of pollution entering oceans?
shipwrecks, dumping, airborne
What are PAHs and why do they tend to become concentrated in marine sediments?
How does “oil” differ depending on the variety?
What is the behavior of spilled oil?
What are treatments for dealing with oil spills?
Why is there a question about whether or not to spray dispersants on oil spills?
Lecture notes – Chapter 18 (Harvesting the sea)
Fishing adds a predator
Affects target species
– largest individuals are taken first
– average size of individuals decreases
Canadian West Coast ling cod
South African pilchards
– not necessarily damaging until size decreases to
size of reproductive maturity
Affects predators of target species
Pinnipeds feeding on pollock in Alaska
Affects prey of target species
Krill near Antarctica
Fishing can impact non-target species
Pacific squid drift nets and incidental catch
4,000 northern fur seals
186,000 dark shearwaters
228,000 skipjack tunas
1,163,000 blue sharks
Pacific yellowfin tuna fishery in 1960s
200,000 to 500,000 dolphins
Ghost fishing (abandoned gear or nets)
Overfishing – fishing harder than needed
It is probable that we could catch more fish with less effort in most fisheries
Maximum sustained yield (MSY)
maximum tonnage of organisms that could be taken from a harvested
population each year without eventually destroying the population
measured in metric tons (tonnes)
Catch per unit effort (CPUE)
tonnage of the catch divided by the amount of effort invested in
– CPUE goes up quickly in unexploited population
– increases until MSY level is reached
– then CPUE goes down
– best if intermediate-size individuals are selectively taken
– this leaves the fewer, larger, individuals for reproduction
plaice prior to WWII
Global fisheries –
Are we close to the MSY for all the oceans?
– United Nations estimates by Food and Agriculture Organization (FAO)
– these do not include “artisanal” catch (taken by individuals for their own
food or for trading)
– artisanal catch is estimated to add another 28%
John Ryther (WHOI) has estimated the productivity of all oceans (Fig. 18-9)
– his estimate of 242 million tonnes is approx. 3X 1987 harvest levels
– estimates for MSY for all oceans varies from 60 to 100 million tonnes
– United Nations assessment from 1987 reports that only 25 of the
280 stocks of fishes worldwide are presently “underexploited”
or “moderately exploited”
Krill is the most significant stock that is presently underutilized
– these are near Antarctica (as unaccessible as they can get, making
their havest costly)
– they taste/appear like cooked maggots
– market for “fish meal” is uncertain
– present high levels are likely a reflection of removal of baleen whales
– exploiting these stocks would likely affect the many mammals and
birds that depend on them
In terrestrial environments, we vastly increase the amount of food
that is produced by farming
Some types of aquaculture have tremendous potential for producing
– even though we get only 2% of our calories from
the sea, we get 12% of our protein
– both take advantage of tides to bring food/nutrients to
– both produce much more protein per unit area than
comparable farms on land
Salmon rearing to fry stage is similar in that it takes advantage of the ocean’s
Other types of aquaculture require 4 to 8 times more protein than they provide
Aquaculture can also have many damaging effects
compete with native populations
introduction of invasive species