Prelim 2 Flashcards
Drew Harvell Lecture:
What will happen by the year 2100?
By the year 2100, without changes, more than half of the world’s marine species may become extinct.
Drew Harvell Lecture:
What are Marine Protected Areas (MPAs)?
Marine Protected Areas conserve the biodiversity of the oceans and maintain productivity of fish stocks.
Drew Harvell Lecture:
How much of the land area is protected?
About 12% of the land area is protected in comparison to 1% of the world ocean and seas.
Drew Harvell Lecture:
What organisms are in danger of extinction?
Sharks & rays and corals. Sharks & rays are in more decline than corals. Corals are in steep decline but not as bad as sharks & rays.
What is the generation of CO2?
Respiration
What is Net Primary Production (NPP)?
Net Primary Production is the difference between the amount of CO2 consumed by photosynthesis and the amount of CO2 produced by respiration.
It is the net gain or net loss of carbon within the cell.
What happens to light levels below compensation light level?
Phytoplankton cells have insufficient light to photosynthesize to meet basal metabolic needs and cell respiration exceeds photosynthesis, leading to negative values of net primary production.
What happens to phytoplankton at low light levels, optimal light levels, and very high light levels?
At low light levels, phytoplankton are light limited.
At optimal light levels, phytoplankton are light saturated
At very high light levels, phytoplankton are photoinhibited.
What is compensation depth?
The depth at which ambient light intensity is equal to compensation light intensity.
What is the nutrient dependency of primary production?
At low concentration, the dominant cell diameter of phytoplankton is 1 micrometer.
At middle concentration, the dominant cell diameter of phytoplankton is 10 micrometers.
At high concentration, the dominant cell diameter of phytoplankton is 100 micrometers.
What are the four phytoplankton nutrients of interest to oceanographers and why?
The four phytoplankton nutrients are nitrogen, phosphorus, silica (for diatoms), and iron.
One of these four nutrients can be in short supply and limit growth of phytoplankton.
What is the main source of nitrogen, phosphorus, and silica to the surface ocean?
Vertically mixing or upwelling of nutrient-rich deep-water to the surface.
What is the main source of iron input to the surface ocean and where is iron mainly limited?
The main source is from dust blowing off the continents.
The Southern Ocean is one of the main iron limited regions.
Light and nutrients in surface ocean?
Light is plentiful but nutrients are limiting.
Nutrients and light in deep ocean?
Nutrients besides iron are plentiful but light is limiting.
What are surface and deep waters separated by?
Thermocline
When is primary production enhanced?
High light and high nutrients
What does surface convergence of Ekman Layer in the subtropics (forced by Trade and Westerly Winds) form?
Mounds/lens of warm (low-nutrient) water including gyre rotation and downward surface layer velocity into deeper ocean.
What happens to primary production if surface convergence makes it difficult for nutrients to move upward to surface ocean?
Primary production is low year-round in the subtropical gyres.
Low surface layer nutrients present through all seasons.
What do easterly trade winds cause?
Surface waters to pile up in the west
Where is thermocline deep and shallow?
Thermocline is deep in the west and shallow in the east.
What happens to the proximity of thermocline near surface in the east?
It enhances upwelling of cold and nutrient rich deep water to the lighted region of the surface ocean and enhances biological productivity in the area.
What is tidal mixing?
Tidal mixing happens in shallow continental shelf regions. It is seasonally steady and mixes water column from bottom to top and brings bottom water with rich nutrients to the ocean surface.
What is coastal upwelling?
Coastal upwelling comes from Wind/Ekman Offshore Transport. It is seasonally variable and enhances upward movement of deep water with rich nutrients.
What is subtropical gyre primary production?
It is low primary production year-round because of persistent lens of warm water.
What is equatorial primary production?
It has a modest season in the Atlantic and strong interannual variation in the Pacific due to El Nino.
What is coastal primary production?
It is high year-round especially during upwelling periods in California, Chile, Northwest Africa, South Africa, and Arabian Peninsula.
What is the change in seasonal thermocline depth?
From spring to summer, there is warm water, buoyant, hard mixing, and shallow water.
From summer to winter, there is cold ocean surfaces not as buoyant and deeper water.
What happens to cells below the Compensation Depth?
They lose carbon because of the extreme dim light that allows positive net primary production (NPP).
Why does the average light level that phytoplankton experience over the course of a day becomes dimmer as mixing depth increases?
Cells spend most of the day below compensation depth in the dark.
What happens to cells below the Critical Depth?
Cells spent most of the day below compensation depth and lost carbon.
Net losses of carbon below compensation depth exceed net gains of carbon above compensation depth.
What happens to mixing depth in the winter?
The mixing depth is very deep in the winter.
Light limited and nutrients abundant.
What happens to mixing depth in the spring?
The mixing depth is shallow in the spring.
Light abundant and nutrients abundant.
What happens to mixing depth in the summer?
The mixing depth is very shallow in the summer.
Light abundant and nutrients limited.
What happens to mixing depth in the fall?
The mixing depth is shallow in the fall.
Light modest and nutrients modest.
What is deep vertical mixing in the winter?
It brings high levels of nutrients to the surface and causes phytoplankton to mix below the critical depth, making cells spend time in the dark and NPP light limited.
How is shallow thermocline formed in the spring?
The mixing depth is above the shallow thermocline and above the critical depth, so phytoplankton spend time high in the water column with abundant sunlight.
Nutrients are plentiful from winter mixing, so cells have abundant nutrients and sunlight, causing the formation of a spring bloom.
Why is there continued stratification in the summer?
Mixing is shallow and above critical depth, but nutrients are depleted and NPP is nutrient limited.
Polar ocean regions are the same as temperate ocean, but ice shelf melting enhances stratification.
What is the global distribution of annual net primary production (NPP)?
- Global NPP is about 104 Gt C yr-1
- Terrestrial NPP is about 54% of Global NPP
- Oceanic NPP is about 46% of Global NPP
Why does the Open Ocean contribute more to the global ocean total NPP than the coastal regions?
Open Ocean (Trade Winds, Westerly Winds, and Polar Regions) show less intensities of primary production (NPP per square meter) in comparison to coastal regions (29%). The Open Ocean contributes most (71%) as a whole to the global ocean total NPP because of the vast areas of these regions.
What nutrient is limited in Station Aloha in the North Pacific Subtropical Gyre?
Phosphorus
What nutrient is limited in the Southern Ocean?
Iron
What nutrients limit growth of phytoplankton?
Nitrogen limits growth of phytoplankton in the ocean, but iron and phosphate may limit growth in certain oceanic regions.
What is global ocean primary production?
The global ocean primary production has same magnitude as the global terrestrial system.
Why is the rate of primary production per square meter in the open ocean low?
The region is vast, so the open ocean as a whole contributes to the total global ocean primary production.
What is a holoplankton?
Planktonic organisms that live their entire life in fluid suspension. Examples: 1. Copepods 2. Shrimp 3. Arrow Worms 4. Some Jelly Fish
What is a meroplankton?
Planktonic organisms that spend only part of their life in fluid suspension. Examples: 1. Crabs 2. Barnacles 3. Oysters 4. Fish Larvae
How are complex food webs simplified?
They are simplified by grouping/classifying all species into a small number of broad categories.
How is an individual organism’s membership determined?
- What are the main food sources of the organism?
2. Who are the main predators of the organism?
What is an autotroph (broad grouping)?
Group of organisms whose energy/carbon for growth comes from non-organic sources such as phytoplankton because they use sunlight and CO2 for their energy/carbon needs.
What is a heterotroph (broad grouping)?
Group of organisms whose energy/carbon for growth comes from previously formed organic carbon material.
such as herbivorous zooplankton because they consume phytoplankton for their carbon needs. Carnivores would also be heterotrophs.
What is a trophic level (refined grouping)?
A nutritional feeding level within a food chain or food web such as primary producer (autotroph), primary consumer (herbivore), secondary consumer
(first carnivore), and tertiary consumer (second carnivore).
Is the heterotrophic organism a primary consumer or a secondary consumer or a tertiary consumer etc…?
Optimal prey size is determined by the consumer’s mouth size and, as a rule-of-thumb, prey size is often about 1/10 the consumer’s size.
What two factors does Trophic Transfer Efficiency depend on?
Exploitation Efficiency and Gross Production Efficiency
What is Exploitation Efficiency?
The efficiency with which a consumer population is able to find, capture and ingest all of the potential prey present in the environment.
What is Gross Production Efficiency?
The physiological/biochemical efficiency of converting ingested prey into consumer biomass.
What is the formula for Trophic Transfer Efficiency?
Trophic Transfer Efficiency = (Exploitation Efficiency x Gross Production Efficiency)
What are some strategies for Exploitation Efficiency (game of hide and seek)?
- strategies for detecting prey
- strategies for capturing prey once detected
- counter strategies to avoid detection in the first place
- counter strategies to frustrate capture if detected
Avoid encounters (vertically migrate) or avoid detection (be transparent) and frustrate capture (have spines or be very large or very small).
What is the Diel Vertical Migration (Avoid Detection)?
The zooplankton community migrates up to the surface ocean at night to feed in the dark while avoiding visual predators like small fish.
During the day they migrate down to the safety of the darkness found at depth.
What is Exploitation Efficiency in Spring Blooms in Temperate North Atlantic Region?
Exploitation Efficiency is very low (10%). The phytoplankton not found by grazers (copepods) sink into the deep ocean as dead phytoplankton cells. Grazers enter diapause (hibernation) and become decoupled.
What is Exploitation Efficiency in Tropical Oceans/Environments?
Exploitation Efficiency is very high (90%). Almost all phytoplankton found and consumed by grazers.
What is Gross Growth (Production) Efficiency?
Amount of CONSUMER BIOMASS produced divided by amount of PREY INGESTED. This efficiency ranges between 20% and 60%.
What is Trophic Transfer Efficiency a function of?
Exploitation Efficiency (10% to 90% ) Gross Production Efficiency (20% to 60%)
What is the combined effect range of both exploitation and gross production efficiencies (Exploitation + Gross Production)?
An overall trophic transfer efficiency of about 10% to 20%
Suppose you had phytoplankton productions of 1000 biomass units per year and you had a food chain with 3 trophic steps between phytoplankton and fish that you wanted to catch each year?
phytoplankton (1000) –> zooplankton (100) –> small fish (10) –> your fish (1)
How much fish production would you expect each year if tropic transfer efficiency is 10% for each trophic step?
D) 1 biomass units of fish per year
Why are marine food chains strongly size-structured?
You can guess who-eats-who based on the size of the organisms.
Is the number of trophic levels between phytoplankton and harvestable fish smaller or bigger in high nutrient regions?
Smaller in high nutrient regions such as coastal upwelling regions. Open Ocean (7 trophic levels) Continental Shelf (4 trophic levels) Upwelling Regions (3 trophic levels)
Open Ocean Province
Low primary productivity per square meter. Area extent is large, so overall primary production is high. Small phytoplankton leads to large number of trophic steps (7 total) and loss of (up to 1/10)^7=1/10,000,000 to get to harvestable fish. Does not make up overall primary production and produces small fish production.
Upwelling Province
High primary productivity per square meter. Area extent is small, so overall primary production is low. Large phytoplankton leads to small number of trophic steps (2 total) and loss of (up to 1/10)^2=1/100. Does make up small overall primary production and produce large fish production.
Why study marine microbes?
Proportion of living biomass in the global ocean. Bacteria and unicellular eukaryotes have high biomass.
What is oligotrophic?
Pelagic environment (water column) that has naturally very low plant nutrient concentrations. The vast subtropical gyres are oligotrophic
What is eutrophic?
Pelagic environment (water column) that has naturally high plant nutrient concentrations. The coastal upwelling zones are eutrophic.
What is the Traditional Food Chain Concept?
Organisms are in a given Trophic Level depending on whether they produce chlorophyll or not (Autotrophs vs. Heterotrophs) and on the organism’s size.
What is the source of carbon and energy for heterotrophic bacterial growth?
Heterotrophic bacteria grow on dissolved organic matter released from phytoplankton by steady leakage. It could also be released from cell senescence or sloppy feeding by zooplankton.
Discovery of an Important New Bacteria-Sized Autotroph
Sallie Chrisholm and others discovered a new autotroph in oligotrophic regions using analytical flow cytometry. This important new autotroph is called Prochlorococcus.
What is the New View (1990’s) of Marine Food Webs?
It recognizes the importance of Prochlorococcus.
