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41 Cards in this Set

  • Front
  • Back
• Compensation depth
the amount of light intensity on the light curve where the rate of photosynthesis exactly matches the rate of respiration
• Microbial loop
a trophic pathway in the marine microbial food web where dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton.
• The bathyal zone
) is that part of the pelagic zone that extends from a depth of 1000 to 4000 meters (3300 to 13000 feet) below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. Sunlight does not reach this zone, meaning there can be no primary production.
bycatch
fish caught unintentionally in a fishery while intending to catch other fish. Bycatch contributes to fishery decline and is a mechanism of overfishing for unintentional catch
• Phototroph
organisms that carry out photon capture to acquire energy. They use the energy from light to carry out various cellular metabolic processes
• Heterotrophy
an organism that cannot fix carbon and uses organic carbon for growth.[1] This contrasts with autotrophs, such as plants and algae, which can use energy from sunlight (photoautotrophs) or inorganic compounds (lithoautotrophs) to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon dioxide.
chemotroph
obtain energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which utilize solar energy. Chemotrophs can be either autotrophic or heterotrophic.
phytoplankton
the autotrophic component of the plankton community
zooplankton
heterotrophic (sometimes detritivorous) plankton
benthos
community of organisms which live on, in, or near the seabed, also known as the benthic zone.T
infauna
benthic organisms that live within the bottom substratum of a body of water, especially within the bottom-most oceanic sediments, rather than on its surface. Bacteria and microalgae may also live in the interstices of bottom sediments
epifauna
aquatic animals that live on the bottom substratum as opposed to within it, that is, the benthic fauna that live on top of the sediment surface at the seafloor.
plankton
are any organisms that live in the water column and are incapable of swimming against a current
nekton
aggregate of actively swimming aquatic organisms in a body of water (usually oceans or lakes) able to move independently of water currents.Nekton
trophic efficiency
Generally, each trophic level relates to the one below it by absorbing some of the energy it consumes, and in this way can be regarded as resting on, or supported by the next lower trophic level. Food chains can be diagrammed to illustrate the amount of energy that moves from one feeding level to the next in a food chain. This is called an energy pyramid. The energy transferred between levels can also be thought of as approximating to a transfer in biomass, so energy pyramids can also be viewed as biomass pyramids, picturing the amount of biomass that results at higher levels from biomass consumed at lower levels.
food web
depicts feeding connections (what eats what) in an ecological community and hence is also referred to as a consumer-resource system.
food chain
a linear sequence of links in a food web starting from a trophic species that eats no other species in the web and ends at a trophic species that is eaten by no other species in the web
Maximum sustainable yield
theoretically, the largest yield (or catch) that can be taken from a species' stock over an indefinite period.
Physical factors affecting primary productivity in the oceans
• Abiotic factors like solar radiation and nutrients, and biotic factors like zooplankton predation may affect ocean primary productivity.
• Productivity varies with the season, and also locally and globally. Variation in primary productivity, measured typically as the concentration of chlorophyll in water, is a primary determinant of all biological productivity up the food web and trophic pyramid.
primary productivity - atlantic
\: Large gyre systems, with low productivity. In the north Atlantic, the gyre is called the Sargasso Sea.
primary productivity - pacific
Relatively high productivity, but still low in gyres. What causes these high productivity areas?
primary productivity - indian
Typically low (0.2 gC/m2/day), but depends on seasons and monsoon winds, which can cause upwelling N of equator.
primary productivity- southern ocean
High productivity, high phytoplankton density can yield 1gC/m2/day! Over about 100 day season, that yields 100 gC/m2/year. Production can occur under ice!
local patterns of productivity
1. Shelf areas cover 15% of ocean area, but 50% of oceanic primary productivity.
2. Upwellingzones bring nutrient-rich deep water to the surface, fueling primary productivity
Three major mechanisms: Coastal upwelling, equatorial upwelling, island mass effects
phytoplankton
• Major ecological axes relevant to phytoplankton include light and nutrient acquisition and use, natural enemy interactions, morphological variation, temperature sensitivity, and modes of reproduction. Trade-offs between these traits play key roles in determining community structure. Freshwater and marine environments may select for a different suite of traits owing to their different physical and chemical properties.
• Examples: diatoms, krill, larvae, copepods
Relationships between primary production and fisheries
Most productive areas (phytoplankton productivity/m2 area) are in coastal, upwelling regions
• Because of the vast area of the open oceans, most phytoplankton productivity (on total basis) actually occurs in the open ocean
role of heterotrophic bacteria in the ‘microbial loop’
Heterotrophic bacteria capture dissolved organic molecules from seawater as well as organic particles that they “digest” with enzymes. Some bacteria and archaea oxidize inorganic chemicals for energy, and the carbon they fix into organic matter serves as basis for food webs in diverse ecosystems, including some in seemingly uninhabitable environments
• Relationship between length of the food chain and energy transfer between trophic levels
The biotic elements that comprise an ecosystem fall into one of several trophic levels. The trophic level of an organism is its position in a food chain, the sequence of consumption and energy transfer through the environment.
impact of fisheries on food webs
- anchovies and sardines in CA
basis of life at hydrothermal vents: chemolithoautrophic metabolism
chemolithoautotrophs obtain energy from the oxidation of inorganic compounds and carbon from the fixation of carbon dioxide. An inorganic electron donor yields electrons transferrred to an acceptor. Energyyield is saved as a phosphodiester bond in ATP- required for CO2 fixation
common chemolithoautotrophs at hydrothermal vents
sulfide-oxidizing actera
difference between photosynthesis and chemosynthesis
Chemosynthesis get energy from oxidation of inorganic substance, photosynthesis get energy from light. Chemosynthesis could occur just about anywhere there are enough suitable chemicals to oxidize, photosynthesis could only occur when there is sufficient light.
controls on biodiversity in the ocean
gene flow, dispersal, adaptive value of genetic polymorphisms, determination of dispersal and recruitment, species interactions including invasions, sediment transport, natural and human-induced catastrophes
mesopelagic zone
200-1000 m depth
Twilight near 200m
vertical migrators who come to surface at night
bathypelagic zone
below 1000m
no light, constant cold
full time residents survive w minimal energy expenditure
evidence of climate change in arctic
-Characteristics of sea ice (extent, thickness, fractures, snow cover)
• -Timing and extent of seasonal ice melt
• -Prevailing winds/currents
• -Bottom water temperatures (determine northern extent of some species)

-mortality of young polar bears
organisms in hydrothermal vents/why
Chemistry of vent fluids:
--- rich in dissolved metals
--- low in Magnesium
(signature element for
hydrothermal alteration
and seawater remixing!)
--- no sulfate (geothermally
reduced to sulfide)
--- high sulfide concentrations
--- rich in reduced gases:
hydrogen, methane
--- acidic pH (3.5 - 6)
--- ammonia only at vents
with organic-rich sediment
cover (Guaymas)
Largest free-living, sulfide-oxidizing, chemolithoautotrophic bacteria:
mat-forming Beggiatoa
archaeoglobus profundus- hydrothermal vent archaea- needs over 80 degree temp
What specific problems are associated with trying to harvest fish according to maximum sustainable yields?
--- Usually based on optimistic estimates
--- In case of doubt, “Maximum yield” has
more clout than “sustainable”
--- Neglects system-level effects on a target species
(changing food web structure, habitat destruction)
--- The original maximal population (N max), the
baseline of maximum yield estimates, often
remains unknown and cannot be recovered
after a species has been decimated
--- Bycatch: often more biomass than the target species;
is thrown overboard and discarded
--- 90 million tons official global catch (FAO statistics);
estimated 150 million tons if bycatch is included
What specific factors complicate our efforts to investigate marine organisms and marine environments, in particular deep sea and high latitude environments
--- seldom seen; therefore hard to count

--- technical sampling bias: The mesopelagic and
bathypelagic ocean is difficult to explore and to
survey

--- trawl nets: unsuitable for gelatinous animals
too deep for divers;
this leaves only submersibles and ROVs
(very few are available, extremely expensive to
operate)

--- reliance on chance observation

--- low population densities in a large habitat still
allow large total numbers of individuals
How do the Arctic and Antarctic environments differ?
Common features structuring polar environments
• Primary productivity (the base of the food web) is light-limited for significant parts of the year
• Extensive ice coverage structures the physical environment, greatly affects polar regions as habitats
• Human activities have had a significant impact in both the Arctic and Antarctic
Differences
• Nature of ocean basins, major circulation patterns
• Terrestrial components of food webs (or lack thereof)
• Prevalent food webs
• Relationship between territory and national sovereignty
• Extent of human habitation
• Critical issues with respect to climate change
• Prognosis for the future
organisms have been discovered in deep water over past decades
Example for
unknown marine
Biodiversity:
A new bathy-
pelagic squid

Known only
from chance
submersible
encounters
Ten extremely
elongated arms
and tentacles

A new species of shrimp, Neoglyphea neocaledonica, found in the Coral Sea; thought to be extinct for 50 million years