Marine Biology Final
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Define ‘ecosystem’, ‘community’, ‘species’, ‘niche’
- Ecosystem: a community or communities plus their physical environment interacting in a large more or less self contained area
- Community: populations of different species that live and interact at a particular location
- Species: genetically related individuals that can readily interbreed
- Niche: role of a species in an ecosystem
Name the 6 layers of the ocean
- Intertidal: between high and low tide mark
- Benthic: anywhere on bottom
- Epipelagic: top layer of ocean (100-200m)
- Mesopelagic: second layer of ocean (1000m down)
- Bathypelagic: third layer of ocean (4000m down)
- Abyssopelagic: Bottom of ocean (<4000m deep)
Define ‘nekton’, ‘plankton’ and ‘benthic’.
- Nekton: swims
- Plankton: drifts
- Benthic: lives in or on bottom
Define ‘food web’
- All of the interconnected feeding relationships within a community
- complex in oceans
Define the three main steps in a marine food chain?
- primary producers
- primary consumers
- secondary consumers
What is primary production? How is it measured?
- Production of organic carbon
- measured via photosynthesis
What is ‘carrying capacity’ and why it rarely reached?
- Amount of organisms a given area can sustain
- reached due to fluctuations in nutrients and organisms
What is an ‘abiotic factor’?
- Waves and currents
Describe two key abiotic factors that play dominant roles in most marine ecosystems
- Light = energy for primary producers to grow
- Temperature = energy to grow
What is a ‘biotic factor’
- competition for resources
- predator-prey interactions
Describe 2 biotic factors that play dominate roles in most marine ecosystems
- Food (for primary production)
- predator prey (even balance or one will go extinct)
Define ‘mutalism’ and give an example.
- Benefits all parties
- remora on sharks
Define ‘intertidal zone’
Locations where organisms are routinely exposed to air at low tide (emersion) and to the sea at high tide (immersion)
What are the three basic types of intertidal communities?
- Rocky (or hard bottom)
- Gravel (extremely high energy)
- Soft bottom (sand=high energy, mud=low energy)
How does wave action drive organismal form and function in the rocky intertidal zone?
Organisms need to be tough (like holdfasts in kelp in high current)
How do tides drive organismal form and function in the rocky intertidal zone?
Usually have attached organisms (mussels/algae)
What is a tide pool?
- Special places in the rocky intertidal that have water trapped at low tide
- harsh competitive environment
- simple communities (algae, herbivores)
Why are most rocky intertidal organisms filter feeders?
- Cannot dislodge to hunt
- much plankton and detritus available
How do macroalgae typically cope with wave shock?
What is ‘zonation’?
Combination of abiotic and biotic pressures
Describe the three zones that are evident in all rocky intertidal ecosystems
- Upper intertidal = physically dominated
- Middle intertidal = barnicles, mussles, submerged/uncovered daily
- Lower intertidal = only exposed during spring/low tides
Compare and contrast in some detail the roles of abiotic and biotic factors in determining zonation patterns in the rocky intertidal.
- Abiotic: constant daily stress, sudden extreme events like storms
- succession to recover
What is a byssal thread?
what mussels use to attach themselves to substrates
How do most intertidal organisms reproduce and then disperse?
Name two types of organisms usually found in the middle intertidal zone of rocky shores.
Why is competition for space so common in the rocky intertidal?
there is only so much room to attach
What is a gravel intertidal beach ecosystem?
- eroded rocky shore lines
- Shifting rocks/ gravel
- Very, very simple and limited infauna because of shifting gravel
Describe both types of soft bottom intertidal ecosystems.
- Antarctic soft bottom = productive, undisturbed
- Tropical =
What physical factors determine the nature of intertidal organisms found in soft bottom communities?
- wave action
- salt concentration
What are infauna?
- Infauna = organisms in sediments
- worms, molluscs
What is an estuary?
Semi-enclosed areas where fresh and salt water mix
What are the two types of estuaries as defined by their salinity profiles?
- Well-mixed - gradual top-to-bottom mixing (ex. broad shallow regions; lagoons)
What is salt wedge and how does it determine the distribution of estuarine organisms?
Waters with different salinities slide over each other as tides change
How productive are estuaries and why?
nutrient mixing = VERY PRODUCTIVE
Name and describe two ways that estuarine organisms cope with salinity.
- Stenohaline = intolerant of salinity change
- Euryhaline = tolerant of salinity change
- (osmoregulator = an animal that can regulate osmolarity (may or may not be stenohaline))
What ecological roles do birds play in mudflats?
- specialized predators and feeders
What is a salt marsh?
- Marine wetlands (very low energy enviroment)
- -Dominated by grasses
- -Detritus and bacteria play a key role
- -Provide shelter for many organisms
Describe the dominant type of plant in a salt marsh.
seagrass and mangroves
What is a mangal?
a mangrove forest
Where are mangals found and what ecological role do they play in coastal zones?
- found around equator
- play large role in nursery and shrimp production
Describe the role of detritus in a typical estuarine food web.
deposit and filter feeders eat this
Define and then describe 3 features of the continental shelf.
- areas of the continent that were flooded during ice age
- steep slope
- 200m deep max
- well mixed
List the 4 types of benthic communities that are found on the continental shelf and describe 4 features of one of these.
soft- bottom:vegetated or not
hard- vegetated or not
Softbottom vegetated - low wave energy
Shallow: high nutrient loads from shore,high standing biomass
What are two major sources of nutrients to continental shelf communities?
- detritus from inshore
Why is the distribution of benthic organisms over the continental shelf often patchy?
- larval dispersal
- also based on sediment type
- marine angiosperm
- from the lily family
What are epiphytes and what roles do they play in a vegetated, seagrass community?
- little guys stuck to sea grasses (snails, green algae)
- nitrogen fixation
Why are seagrasses disappearing?
- development and pollution
- nursery areas
What is the single biggest difference between vegetated and nonvegetated soft bottom communities other than the plants?
the presence of herbivores
Define ‘infauna’ and describe its ecological role in a soft-bottomed community.
10. Define ‘infauna’ and describe its ecological role in a
carbon and nutrient recycling via detritus
What 3 strategies do epifauna employ to survive in soft-bottomed communities?
- poisonous and display
Where do nudibranchs get their poisons?
What 3 aspects of their appearance can octopuses rapidly change?
Where are kelp forest communities found and why?
- east sides of gyres
- need stable cool temps for kelps
What role do sea urchins play in kelp communities?
Why are otters ‘keystone’ species in kelp communities?
Eat urchins which have domino effect
What is a ‘reef’? list the two types
- underwater structure
- abiotic or biotic
What is coral?
members of the class Anthozoa with a calcium carbonate skeleton
What is a coral reef? How many types are there?
- reef made of corals –term sometimes includes hydrozoans
- fire coral
How productive are scleractinian coral reefs relative to other ecosystems?
- some of most productive on earth
Where are coral reefs found and why (at least three
- Eastern sides of continents (due to currents) and in 30 degree latitude or less
- nutrient load
What is a cnidarian coral? A hermatypic coral?
- A scleractinian coral
- only has POLYP stage
How can a scleractinian coral reef be so productive?
- then high recycling within the system
What are three defining features that explain interconnections of scelertinian coral polyps?
- connected nervous systems
- connected digestive systems
List 3 of the many ways that reef-building corals obtain nutrients.
- deposit feeders
- absorb nutrients
What zooxanthellae? What do they do?
- internal photosynthetic algae
- most are dinoflagellates
- get CO2
- produce O2, calcium carbonate and organic carbon
How important are zooxanthellae to corals and how do they determine the distribution of this organism?
- receive oxygen from photosynthesis
- necessary for coral life
- need specific levels of light year around
Aside from scleractinian corals, what other organisms contribute to coral building?
How do corals reproduce? When and how do they do this?
- most broadcast spawn (but also budding)
- they do this at night
- spit gametes through mouth
How many types of reef are there? Define one
- fringe - form a narrow band close to shore
- barrier - separated from shore by a lagoon
- atoll - a ring reef (extremely old!)
Describe the zonation process and structures in one type of a coral reef.
- Abiotic factors (wind, sunlight)
- near intertidal mark to biotic deep
What role does detritus have in coral reef food webs?
- food for deposit feeders
- comes from feces and external sources
What is coral rubble?
- base of reef
- form foundation
Why is space so limiting on coral reefs and explain how coral compete for it?
- light availability
- they try to kill each other
Describe predation pressure exerted by fishes on corals reefs?
- extreme pressure!
- eat each other and eat corals
How is symbiosis important in coral reefs?
- essential for rebuilding
- provide oxygen to cnidarians
- responsible for CaCO3 deposition
Describe 3 ways man’s activities threaten reefs.
- nutrients - higher nutrient inputs can lead to hypoxia
- salinity - can endanger sensitive organisms that are not able to cope
- overfishing - can mess up complex food webs
Describe/define the ‘epipelagic zone’?
- Top 200 m of oceanic waters
- excludes the estuaries
What two regions comprise the epipelagic zone?
- Neritic - over the continental shelf
- Oceanic - beyond shelf
Describe three features of life in the epipelagic
- Generally sparebut patchy
- complex food webs
- small (200 meters)
What is the microbial loop? Which section of the ocean is it located?
- bacteria and viruses
- reprocesses detritus and plankton to liberate dissolved organic carbon
What role does detritus play in epipelagic foodwebs?
- it mostly sinks so....
- Very little role except through microbial loop
How productive are epipelagic food webs and why?
- Not very
- no nutrients except in upwelling and downwelling regions
Define the term ’plankton’
Drifitng organisms that are too small to be self-propelled
What are 'netplankton?'
8. What are ‘netplaknton’?
- Plankton that can be caught in nets
- 20 microns to 20 cm in size
What is the most important (common) type of picoplankton?
- reponsible for 90% + of the ocean’s primary production!
What are zooplankton?
- animal plankton
- mostly carnivores
- some herbivores
What is a copepod?
- Small crustaceans (75% of zooplankton)
- largest animal biomass on Earth!
What is krill and why is it important to whales?
- Second most abundant zooplankton (decapod)
- major food source for whales
What features characterize epipelagic zooplankton and why?
- Transparent - camoflauge
- buoyant - unable to swim on their own
- small - protection
What is vertical migration and why is it important?
- Largest movement of animals on earth
- every night
- drives food chains
What are nekton’?
- Large self-propelled organisms
- Dolphins, tuna, birds
Where and what do nekton eat and live?
- Large predators (dolphins, birds, fish, whales)
- constantly roaming looking for upwelling regions and food patches
What makes a tuna a ‘swimming machine’?
- warm blooded
- great sensory system
Describe the arctic.
- Ice-covered ocean surrounded by continents
- Huge ice sheet
- fluctuating pack ice
- seasonal river input
What is ‘fast ice’?
Ice frozen to shoreline of coast
Compare and contrast nutrient availability throughout the year at the north and south poles.
- North: variable and lower on avg
- South: high with more krill
- Both: highly seasonal primary production
Describe the nature of the summer-time arctic ocean food web
- consumer-driven web
- ultimately based on plankton blooms
What ecological roles do seals play in the Arctic? How many species are there?
- Huge fish eaters
- 3 - ringed, harped, hooded
What animal is at the top of the Arctic foodweb?
Are odontocetes (toothed whales) found in the Antarctic? Which bird species is only found in the Antarctic?
- No odontocetes in Antarctic
- Penguins in the south!
Where do Arctic baleen whales go during the winter months and why?
- South because...
- there is no food in the North during this time
Antarctica surface waters are a constant -2 C year-round. Why?
- Cooling effects of the continental Antarctic
- nutrient cycling via upwelling creates a nutrient-rich surface
Why do all organisms living on Antarctica depend on the marine environment?
There is no food on land (its frozen solid year-around)
What are ‘krill’ and what role do they play in the Antarctic
- Large, long-lived decapods
- eat plankton
- is the source of food for all consumers
What is the Antarctic circumpolar current? What drives it? How does it distribute waters?
- a slow current that circles the continent
- Wind driven
- Mixes and distributes deep and intermediate waters from Atlantic, Indian and Pacific oceans
What is the sea-ice boundary and why is it so important to ecology for the Antarctic?
- it is on the east side of the continent, where ice and ocean meet
- where it is thick, most life is present
- where thin, Salpa thompsoni (a small tunicate) is present
What is so special about Nototheonoid fishes?
- 47% of all fishes in the Antarctic
- make up 90% of biomass in this area
Describe a few distinguishing features of Weddel seals
- hold breath for 60-80 min
- aggressive predators
What do Orcas feed on?
What is noncolleagative freezing?
- Fish antifreeze,
- prevents enucleation of cells
What is spermaceti and what function does it serve?
- Allow animal to dive deeply by using blood temperature to regulate density of lipids
an organized effort to catch fish or other aquatic species to provide food for human consumption, amusement, or industry
Fisheries can be classified by their goals (benefits to humans), of which four are commonly identified. What are these and describe two.
- Ornamental - aquarium trade
- recreational - sailfish, tarpin
- industrial - animal foods (fish farms, poultry)
- food - for humans
What is a ‘specialized fishery for human food’ and why are they so important from a global conservation perspective?
- Fisheries for food
- items that are worth far more than their value as protein alone
- as the fish get rarer, their price increases as does their demand
- DANGER DANGER DANGER!
By weight what group of fishes dominate the world fisheries and why?
- from upwelling regions
- there are lots of them worldwide
What is the United Nations Convention on the Law and Sea (UNCLOS) of 1982 and why is it so important to global fisheries?
- Exclusive economic fishery zones set
- 200 miles from shore
- coastal country has EXCLUSIVE rights to all natural resources in this area
What country is responsible for most of the world’s fish
What are the two basic ways of managing a marine fisheries?
- restricted access
- open access
What is ‘maximum sustainable yield’? Draw and explain this
relationship and why it does not work
- parabola like in ecology
- there is always poaching and illegal capture of fish
- difficult to measure populations of fish worldwide
What is the ‘tragedy of the commons’? How does it pertain to bluefin
- Maximum sustainable yield via self-regulation
- The ‘right’ to use common property (international waters)
- bluefin tuna is now endangered
What is ‘fishing down the food chain’?
- How to capture and use small animals for bait
- Has large scale effects on oceanic food chains
What is a marine sanctuary? How might they help stabilize global fisheries?
- defined area within or adjacent to the marine
- environment, protected by legislation with the
- intent that its coastal biodiversity
- enjoys a higher level of protection then its
- could bring back populations of endangered or threatened fish species
- allow them to spawn
What is a ‘fish stock’?
A defined population of fish with its own genetic and ecological identity
When was the Atlantic cod first fished?
- Vikings and then....
What attributes of its biology made the cod made it so susceptible
easy to catch due to spawning aggregations
What has happened to the age/size of Atlantic cod breeding
stock as a result of continued heavy fishing pressure?
- age has decreased
- size decreased
- health decreased
Have Atlantic cod been driven to the point that they cannot
recover? Have other species replaced them in their ecological niche?
- Maybe – this is an example of fishing ‘down the web’.
- Certain species of shark may have replaced them
Name three species of fish that are fished sustainably and that Seawtch suggests you can eat?
- Alaska wild salmon
What is 'aquaculture?'
the growth and harvesting of aquatic organisms
Aquaculture in the marine environment
What is closed aquaculture?
- land based-systems
What is open aquaculture?
it is open to the ocean in some way (net pen)
What percentage of the fish we eat presently comes from
About a third
Why is mariculture growing so quickly?
- high value and success
- 325 species can be raised this way
What environmental factors limit the aquaculture of marine
Describe two serious ecological problems of Atlantic salmon
- Disease - if one fish gets it, the rest of the crop dies off too
- food waste - it is biologically and monetarily expensive to feed them
- escape - interbreeding and hybridization of wild fish
What country cultures
the most fin by weight and what is it?
Describe an intense form of mariculture that is
- do not require feeding such as salmon and other larger fishes
Why is preserving marine habitat in the ocean difficult?
- no one owns the oceans
- high level of connectivity
What was the ‘Freedom of the Seas’ understanding?
- That the country had jurisdiction out to 3 nautical miles (basically as far as a cannon would shoot)
- a Dutch law
What is the UN Convention of the Law of the Sea III (UNCLOS)?
- defines the rights and responsibilities of nations with respect to the oceans,
- establishes guidelines for businesses, and protocols for managing marine
- protected areas. 158
- countries have signed but not the USA (why?)
What is a ‘Economic Exclusive Zone’ (EEZ)? Who has exclusive rights there?
- from the coast to 200 nautical miles off shore
- the country has all rights in this area
What are ‘Territorial seas’?
Sea within 12 nautical miles of shore
What are ‘High Seas’?
Non internal or territorial areas of the ocean
What is a ‘Marine Protected Area (MPA)’?
’any area of the intertidal or subtidal terrain, together with its overlying water and associated flora, fauna, historical and cultural features, which has been reserved by law or other effective means to protect part or all of the enclosed environment’
How many MPAs are there?
Over 5000, but 20% of the ocean is recommended
What was the first Marine Protected Area?
Pelago Sanctuary for Marine Mammals (Italy and France)
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