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OCNG 251: FINAL EXAM
species success depends upon |
-finding food
-avoiding predation
-reproduction
-accommodate physical barriers to movement |
plankton |
floater, cannot swim faster than the current
high surface area to volume ratio
need to be small to float and stay alive |
nekton |
swimmers, above the bottom, faster than the current
most adult fish
marine mammals
marine reptiles |
benthos |
bottom dwellers
can live in buried sediments on seafloor
most abundant in shallow water
many live in perpetual darkness, stillness and coldness
|
phytoplankton |
autotrophic
primary producers (photosynthesis)
ex: coccolithophores, diatoms, dinoflagellates (have tails) |
zooplankton |
heterotrophic (consume phytoplankton or other zooplankton)
water is viscous because operating on molecular level |
life cycle of a squid |
benthic egg sacs
zoolpankton larvae
nektonic adults --> mating |
number of marine species |
more land species
ocean has relatively uniform conditions
less adaptation required, less speciation
overwhelmingly benthic (98%), rather than pelagic |
physical support adaptations |
buoyancy to resist sinking (oil)
different support in different temperatures (warm = more appendages) warm water is less dense
high surface area to volume ratio (more appendages) |
viscosity and streamlining |
streamlining is important for larger organisms
less resistance to fluid flow
flattened body
tapering back end |
temperature and marine life |
narrow range of temp in ocean
deep ocean is nearly isothermal |
reasons for ocean stability |
higher heat capacity of water
ocean warming reduced by evaporation
solar radiation penetrates into ocean layers
ocean mixing |
cold v warm water species |
smaller in warm water
more appendages in warmer seawater
tropical organisms grow faster, die sooner, reproduce more
more species in warmer water |
Salinity Adaptations |
extracting minerals from seawater
high concentration to low concentration
cell membrane permeable to nutrients
waste passes from cell to ocean |
osmosis |
water molecules move from high concentrated to less concentrated solutions
|
osmotic pressure |
in more concentrated solutions, prevents passage of water molecules |
marine fish |
drink large quantities of water
secrete salt through special cells
small volume of high concentrated urine
|
freshwater fish |
do not drink water
cells absorb salt
large volume of diluted urine |
dissolved gases |
animal extract dissolved oxygen from seawater through gills
gills exchange oxygen and carbon dioxide directly with seawater
low marine oxygen can kill fish
|
water's transparency |
many marine organisms see well
some are transparent to help elude predators and stalk prey
|
countershading |
dark on top light on bottom |
water pressure |
many organisms have no inner air pockets
collapsible rib cages |
primary productivity |
rate at which energy is stored in organic matter |
primary producers |
photosynthesis users solar radiation
chemosynthesis uses chemical radiation
|
factors affecting primary productivity |
nutrient availability
solar productivity
|
light transmission |
visible light of electromagnetic spectrum
blue wavelengths penetrate deepest
longer wavelengths (red, orange) absorbed first |
nutrient supply |
cooler and deeper seawater is more rich
coastal upwelling = high productivity
|
polar ocean productivity |
winter darkness, summer sunlight
phytoplankton blooms
zooplankton productivity follows
productivity decreases from UV light
|
tropical ocean productivity |
permanent thermocline is barrier to vertical mixing
low rate of primary productivity due to lack of nutrients
symbiotic algae
recycle nutrients within an ecosystem
|
temperate ocean productivity |
productivity limited by sunlight and nutrients
highly seasonal pattern |
temperate ocean productivity winter |
low productivity
many nutrients
little sunlight |
temperate ocean productivity spring |
high productivity
spring bloom |
temperate ocean productivity summer |
low productivity
few nutrients
abundant sunlight
|
temperate ocean productivity fall |
high productivity
fall bloom |
producers |
nourish themselves
photosynthesis of chemosynthesis
autotrophic
|
consumers |
eat other organisms
heterotrophic |
decomposers |
break down dead organisms or waste |
trophic levels |
chemical energy transferred from producers to consumers
about 10% energy transferred to next trophic level |
food chains |
primary producer -> herbivore -> one or more carnivores |
food web |
branching network of many consumers
consumers more likely to survive with alternative food sources |
biomass pyramid |
number of individuals and total biomass decreases at successive trophic levels
organisms increase in size |
marine fisheries |
commercial fishing
most come from continental shelves
|
marine fisheries |
over 20% from areas of upwelling that make up 0.1% of ocean surface area |
bycatch |
non-commercial species are taken incidentally by commercial fisheries
can make up to 8 times more than intended catch
birds, dolphins, turtles, sharks
purse seine nets |
standing stock |
mass present in ecosystem at any given time |
overfishing |
fish stock harvested too rapidly, juveniles not sexually mature to reproduce
reduction in max sustainable yield |
overfishing |
80% of available fish stock fully exploited, overexploited, or depleted/recovering
large predatory fish reduced
increased fish production, decreased stocks |
ozone depletion |
scientific understanding
montreal protocol
global participation, technological solutions, willingness of developed countries to help underdeveloped countries
|
global warming |
scientific understanding
Kyoto protocol
lack of global participation
lack of willingness to help |
fisheries management |
regulate fishing, enforcement of regulation is difficult, governments subsidize fishing |
reef |
shallow water communities restricted to tropics |
polyps |
individual corals |
zooxanthallae |
gives color, photosynthetic, grow best in limited nutrient environment |
zooxanthallae |
shrimp farming harms these because nutrients are injected into the environment attracting phytoplankton |
conditions for coral reef development |
warm but not hot seawater
sunlight from symbiotic algae
strong waves/currents
clear seawater
normal salinity
hard substrate |
coral reef zonation (bottom up) |
ancient coral reefs -> insufficient sunlight for growth
active coral reef -> builds up over time as volcano sinks (50m)
20 m 20% of surface light remains
reef flat/crests at surface
|
importance of coral reefs |
largest structure created by living organisms
great diversity of species
important tourist locales
fisheries
reefs protect shorelines |
humans and coral reefs |
fishing, tourist collecting and sediment influx due to shore development harm coral reefs
sewage discharge and agricultural fertilizers increase nutrients in reef waters
|
coral reef declines |
30% healthy today
1/3 of corals in high risk extinction
humans are greatest threat
|
coral bleaching |
loss of zooxanthallae triggered by stress
often followed by morality
affects symbiotic organisms
|
deep ocean floor communities |
expensive to explore the deep
limited oxygen
robotic technology for exploration |
deep ocean physical environment |
no primary productivity
only 1-3% of euphotic food present
special adaptations for detecting food
|
deep sea hydrothermal vent communities |
discovered by Alvin in 1977
galapagos rift in Pacific Ocean
water temp 8-12 C
chimney vents (black smokers)
chemosynthesis
|
hydrothermal vent species |
giant tubeworms, giant clams, giant mussels, crabs,
supported by chemosynthesis |
hydrothermal vent communities |
vents are active for decades or years
animal species similar at widely separated vents
larvae drift from site to site |
what does not limit coral growth |
high concentrations of calcium carbonate
|
if an ecosystem has four trophic levels and primary production of 100,000 how much energy will top producer get |
100 |
in temperate oceans during summer: |
nutrient concentrations are low, solar input is high and oxygen solubility decreases |
jellyish (B, P or N) |
plankton |
barnacle (B, P or N) |
benthic
|
whale (B, P or N) |
nekton |