Lecture 7 + 8 Flashcards
Which of factor is most responsible for creating new variation for natural selection to work with?
Mutations – they create new variation for selection to act on. Even if a trait is fixed, a mutation could create a new variant.
Biodiversity is great at deep sea hot vents. One type of organism you would expect to see at these vents is:
A chemo-autotroph
In upwelling systems….
- Nutrient rich deep open waters move upward
- Warm water from the deep ocean always moves upward to mix with cold surface water
- Water moves faster to the north than to the south
- Deep water volcanos essentially boil water causing bubbles to rise upward from the deep ocean to the surface
Nutrient rich deep open waters move upward
Which of the following statements concerning estuaries is true?
- Estuaries have a higher salt concentration than fresh water systems
- Estuaries have a lower salt concentration than fresh water systems
- Estuaries and the open ocean have equal salt concentrations
- Estuaries have a higher salt concentration than the open ocean
Estuaries have a higher salt concentration than fresh water systems
True of false: Light penetration is higher in the open ocean than in coastal waters
True
What percent of Earth is covered by oceans?
71% and is 97% of water on earth
- streams, rivers, ponds, lakes, and wetlands cover 0.25% of surface area of Earth and is 0.007% of water on Earth
Some of the major ocean biomes
- DEEP ocean
- subtropical gyres
- upwelling areas
- northern latitudes
- continental shelves
- estuaries
Below ___m, too little light anywhere in the oceans to support photosynthesis
200m. There is more light penetration in the open ocean than coastal waters because there is more algae, other organisms in coastal waters that block light.
What is the average depth of oceans? What is the deepest part?
Average depth of 4.3km. Deepest part is 10.9km.
- 96% of the volume of the ocean is in this “deep ocean” in the dark at depths greater than 200m
- oceans are temperature stratified
- deep ocean waters are very cold (4-5ºC everywhere)
What is the biodiversity of the deep ocean?
The deep ocean has extraordinary biological diversity, including worms, crustaceans, mollusks, and fish found nowhere else.
Many of the invertebrate animals are tiny, have very low metabolic rates, and possess a lifespan that may last for decades.
With no photosynthesis (primary production), what supports animal and bacterial life in the deep oceans?
Mostly supported from organic material sinking from surface oceans (“rain of detritus”)
Hydrothermal vents put out chemical energy, which is harvested by “autotrophic” bacteria that can fix CO2 and produce organic matter.
- Fascinating discovery (in 1970s), and locally important. But not all that important at scale of entire deep ocean
What does the temperature in the deep ocean do to organisms’ metabolisms?
Slows metabolism of bacteria and cold-blooded animals
Which best describes a consequence of the cold
temperatures in 96% of the volume of the oceans?
A) low rates of bacterial decomposition, so large quantities of organic matter preserved
B) slow bacterial decomposition, but animals consume organic matter, so little organic matter preserved
C) low activity by both bacteria and animals, leading to massive preservation of organic matter
D) low activity by both bacteria and animals, but the input of organic matter from surface waters is so low that little organic matter is conserved
B) slow bacterial decomposition, but animals consume organic matter, so little organic matter preserved
Why do bacteria not seem very important in decomposing organic matter in deep oceans?
Probably because of pressure in addition to cold. Also, because little organic matter survives in deep ocean long enough for bacterial populations to grow up and use it. Animals consume most of the sinking organic matter first.
How much organic matter is stored in the deep oceans?
Very little, much less than in terrestrial ecosystems, although some stored in shallow ocean systems.
Oceans are very important in taking up and storing some of the carbon dioxide released by humans, but the storage is as dissolved inorganic carbon in the deep Oceans.
How are surface ocean waters and deep ocean waters separated?
They are separated by strong temperature stratification.
In very shallow waters near land, photosynthesis is often ____. Who are the primary producers?
High. Primary producers include phytoplankton (micro-algae and cyanobacteria), but also larger algae attached to bottom, seagrasses (vascular plants), symbiotic algae in corals.
Seagrasses, corals, and macro-algae attached to the bottom can only live where ____.
Light penetrates to the bottom
- in most of the ocean, phytoplankton are dominant primary producers (including photosynthetic cyanobacteria as well as algae)
Terrestrial biomes are structured by gradients of
Temperature and moisture
Ocean biomes are structure by gradients of
Light and nutrients
- subtropical gyres: low nutrients, deep light penetration
- continental shelf waters and upwelling regions: low-ish nutrient inputs, shallow-ish light penetration
- productive estuaries: big range of nutrients, shallow light penetration
Subtropical oceanic gyres
Large water parcels isolated from the rest of oceans by circular currents (“gyres”) for surface oceans and temperature stratification for the deep ocean
Subtropical oceanic gyres characteristics
- after deep ocean, largest biome on Earth (by far!)
- cover half the surface area of the oceans (35% of the entire surface of the planet!)
- very high diversity
- very low rates of photosynthesis (lowest on planet for aquatic ecosystems, comparable to least productive deserts)
Subtropical oceanic gyres have the clearest water on Earth and the deepest light penetration. So why is primary production so low?
Nutrients are extremely low (comparable to distilled water)
- although high nutrients nearby (!!) in deep ocean waters
- stratification keeps the high nutrients of the deep ocean away from surface waters
-> but photosynthesis only occurs in surface waters, due to light
Low nutrient levels:
a) have little influence on size of phytoplankton
b) lead to small phytoplankton
c) lead to large phytoplankton
Lead to small phytoplankton
- high surface to volume ratio (lot of sites for enzymes to take up nutrients relative ot mass of chlorophyll)
-> long food chains –inefficient, so less production of top predator fish per unit of primary production
Sargasso Sea
In addition to phytoplankton, a floating Sargassum weed (macro-algae) in the Sargasso Sea (but not other gyres)
Upwelling
Result of interaction of prevailing winds interact with coastlines
- brings cold, deep-ocean waters to the surface
-> also nutrient rich
Light penetration of continental shelf waters and upwelling regions
Relatively low (due to scatter and absorption by phytoplankton)
- but the upward flux of water keeps phytoplankton buoyed in the light
- high rates of photosynthesis northwest of South America and middlewest of Africa, northeast of China, northeast of USA, western Europe
-> high photosynthesis also supported by mixing of nutrient-rich ocean bottom waters onto shallow continental shelves
Upwelling ecosystems
- high productivity
- relatively small area of the oceans (5%)
- relatively low diversity
- large phytoplankton
- short food webs
- very productive fisheries (25% of total ocean catch)
What is the size of phytoplankton in areas with high levels of nutrients?
Large phytoplankton –have low surface to volume ratio (less need for enzymes to take up nutrients)
- short food chains
-> efficient, so high production of fish per unit of primary production
Estuaries and coastal shelves characteristics
- often very high nutrients from land (and some from deep ocean)
- low light penetration (suspended sediment, plus phytoplankton absorption)
- often shallow, so sufficient light (even with low penetration)
- high productivity
- relatively low diversity (as in upwelling)
- large phytoplankton (as in upwelling)
- short food webs (as in upwelling)
- very productive fisheries (as in upwelling)
High latitude waters
Away from shore and quite productive
Photosynthesis is moderately high in the high-latitude ocean waters because
The waters are stratified, but more weakly than in the subtropical gyres (allowing a balance of some nutrients from below yet sufficient light)
Nutrients (nitrogen and phosphorous) come from
- river inputs from land
- deep ocean (where nutrients are very high, due to slow decomposition of organic matter than sinks there)
- only in the very surface of the ocean is there enough light for photosynthesis
Photosynthesis is controlled by mixing of the surface ocean waters (in turn controlled by climate):
- if no mixing, no nutrients from bottom waters
- if too much mixing, phytoplankton are mixed too deeply and get too little light
- more wind and less heating in the higher latitude waters than in subtropical gyres, so more mixing and less stratification
- but not too much mixing, so good balance between light and nutrients
Photosynthesis is high only when
Both nutrients and light are high
Comparing all the Earth (land and oceans):
A) most photosynthesis is on land, but the biomass in the oceans is greater
B) most photosynthesis is in the oceans, but biomass on land is greater
C) photosynthesis is roughly equal on land and in the oceans, but biomass in the oceans is greater
D) Photosynthesis is greater on land, but biomass is roughly equal on land and in the oceans
E) Photosynthesis is roughly equal on land and in the oceans, but biomass is greater on land
Photosynthesis is roughly equal on land and in the oceans, but biomass is greater on land
- remember that the area of the oceans is 2-fold greater
- biomass of primary producers turns over much more rapidly in oceans than in forests (or even grasslands)
-> days rather than decades
Large masses of semi-isolated surface water surrounded by a circular current of water moving clockwise would…
Gyres in the northern hemisphere
What is one possible explanation of why biodiversity is very high in subtropical gyres?
The low-nutrient status within a gyre has led to specialized adaptations
Which of the following statements are accurate? (Choose one or more answers)
- The rate of primary production is similar in the ocean and on land
- Total primary production is similar in the ocean and on land
- Terrestrial biomass is less than marine
- Marine biomass is less than terrestrial
- Total biomass is comparable on land and in the ocean
Total primary production is similar in the ocean and on land
Marine biomass is less than terrestrial
Which 2 properties have the greatest impact on structuring ocean biomes?
Light and nutrients
You are eating dinner (an impossible burger) on the deck of a boating trip while passing through a subtropical gyre. Your ship starts to take on water. Everybody is rescued but you did not finish your food. your ship and dinner sink to the bottom of the ocean. What will be the fate of your impossible burger after 2 months?
- The cold and pressure will preserve the burger
- The burger will be gone because it is consumed by bacteria
- The burger will be gone because it is consumed by deep sea animals
- The burger will be gone because it is consumed by phytoplankton
- Impossible burgers float, so it will be consumed by seagulls
The burger will be gone because it is consumed by deep sea animals
Which of the following ocean biomes has the lowest primary productivity?
- Estuaries
- Subtropical gyres
- Continental shelfs and upwelling regions
- Deep ocean
Deep ocean. Subtropical gyres have high light penetration, but low nutrients, however there is still some productivity. No light reaches the deep ocean so there is no productivity.
Which ocean biome has the lowest fisheries production?
Subtropical gyres
What term describes a group of individuals of one species?
Population
Which organism completes its entire life cycle in a single year?
- An annual
- A biennial
- A perennial
- An iteroparous perennial
An annual
Which of the following choices best describes an iteroparous organism?
- An iteroparous species breeds only once and invests all of its energy into reproduction.
- An iteroparous species breeds many times in its life and invests all of its energy into reproduction.
- An iteroparous species breeds many times and invests its energy into reproduction, growth and development.
- An iteroparous species breeds only once but invests all of its energy into growth and development.
An iteroparous species breeds many times and invests its energy into reproduction, growth and development.
