bio 207 chapter 10: an introduction to marine ecology

habitat

the natural environment where an organism lives

habitat characteristics

amount of light, type of bottom, temperature, salinity, waves, tides, currents

habitat

the natural environment where an organism lives

habitat characteristics

amount of light, type of bottom, temperature, salinity, waves, tides, currents

marine ecology

studies how and why marine organisms interact with each other and with their environment, organisms must adapt to biotic and abiotic features

examples of adaptations that are not genetically based

increasing chlorophyll content to trap light, changing growth forms

exponential growth in population

a rapid, unchecked increase in population numbers (explosion), conditions and resources must be perfect

logistic (sigmoidal) growth

as more individuals join a population, resources (food, nutrients, light, space) are used up

carrying capacity

the largest population size the can be sustained by the available resources

limiting resource

a resource whose short supply restricts the growth of a population, causing the population to self-regulate by decreasing growth rate

intraspecific competition

the struggle among individuals of the same species for limited resources such as food, space, or mates

ways that species interact

interspecific competition, predator-prey interactions, symbiosis

interspecific competition

organisms must compete for resources with members of other species, as well as individuals of the same species and could lead to competitive exclusion

competitive exclusion

the elimination of one species by another species outcompeting it

resource partitioning

species can avoid competitive exclusion by sharing a limiting resource, specializing on part of the resource and allowing species to coexist

examples of resource partitioning

eating specific parts of plants, living in slightly different habitats, feeding at different times

ecological niche

the role a species plays in its community, includes all aspects of a species’ lifestyle

examples of an ecological niche

what it eats, where it lives, when and how it reproduces, how it behaves, how it uses its habitat

predation

the act of one organism eating another, carnivory, herbivory, parasitism

the life-dinner principle

a predator risks losing its meal, while a prey risks losing its life
predators adapt to becoming better predators, while prey adapt to avoiding predation
to coexist, a balance is achieved and adaptations are passed on to offspring and the species coevolve

stabilizing selection

moderate features are optimal, future individuals exhibit those features

directional selection

an extreme feature becomes optimal, future individuals exhibit those features

mutualism

both species benefit (cleaning associations)

commensalism

one species benefits with no apparent effect on the other (barnacles living on whales)

parasitism

one species benefits and the other is harmed (tapeworms in the guts of whales)

facultative symbiosis

when partners in a symbiotic relationship can live without one another

obligate symbiosis

when partners in a symbiotic relationship cannot survive without the other partner

symbiont

the smaller partner

host

the larger partner

benthos

benthic organisms, those that lie on or are buried in the bottom, some are sessile and attached to one place

plankton

pelagic organisms that are at the mercy of the currents, drifters, phytoplankton and zooplankton

phytoplankton

photosynthetic

zooplankton

heterotrophic

nekton

pelagic organisms that can swim well enough to oppose the currents, not all are pelagic (skate or ray)

neuston

organisms that float on the surface

littoral or intertidal zone

the boundary between land and sea, the shallowest part of the shelf, the area between the tides, exposed to air during low tide and underwater at high tide

sublittoral or subtidal zone

area of the continental shelf that is never exposed to air, away from the shelf the benthic environment is subdivided by depth below the shelf break

pelagic environment

divided with reference to the continental shelf, 2 zones

neritic zone

lies over the continental shelf

oceanic zone

waters beyond the shelf break

epipelagic zone

the shallowest, 100-200 meters in depth, plenty of light

mesopelagic zone

not enough light to support photosynthesis, the “twilight” zone, 200-1000 meters

deep sea zones

bathypelagic, abyssopelagic, hadopelagic

bathypelagic zone

1000-4000 meters

abyssopelagic zone

4000-6000 meters

hadopelagic zone

depths greater than 6000 meters, deep ocean trenches

autotrophs

get energy from the non-living environment, usually the sunlight. they make their own food from carbon dioxide, water and nutrients

heterotrophs

get energy and organic material from eating other organisms

primary producers

the autotrophs that make their own food

consumers

the heterotrophs that eat

trophic level

each step of a food chain
producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers

energy in each trophic level that is passed down

5-20%, average is 10% (10% rule)

pyramid of energy

can represent the energy passed between trophic levels

pyramid of numbers

represents the actual number of individuals in each trophic level, fewer individuals exist at higher levels

pyramid of biomass

represents the total tissue weight of individuals in each trophic level

the rate of primary production/productivity

the amount of carbon fixed under a square meter of sea surface in a day or in a year, includes the production of phytoplankton in the water column and producers that live on the bottom

gross primary production

the total amount of organic carbon manufactured by primary producers, photosynthesis

net primary production

equals gross primary production minus the organic matter that a producer uses to function, photosynthesis minus respiration

the 3 most important elements

carbon, nitrogen, and phosphorus
originates in the atmosphere, from the Earth’s interior or the weathering of rocks

the carbon cycle

1. carbon begins as CO2 in the atmosphere, dissolves in the oceans
2. converted to organic compounds by photosynthesis
3. respiration converts organic compounds back to CO2
4. some carbon is deposited as CaCO3 in biogenous sediments and coral reefs
5. decomposition allows for the release of carbon in the form of CO2

the nitrogen cycle

1. nitrogen is present in the atmosphere as nitrogen gas (N2), dissolving in ocean water
2. cyanobacteria perform nitrogen fixation which converts nitrogen gas into compounds that can be used by producers (nitrites, nitrates, ammonia)
3. some bacteria perform denitrification which converts fixed nitrogen back to atmosphere nitrogen
4. human activities (agriculture, burning of fossil fuels) have increased the amount of fixed nitrogen

nitrogen fixation

performed by cyanobacteria, converts nitrogen gas into compounds that can be used by producers

denitrification

converts fixed nitrogen back to atmospheric nitrogen

the phosphorus cycle

1. most of the phosphorus enters the oceans by rivers in the form of phosphate (small amount enters from the atmosphere)
2. naturally phosphorus is released from weathering of rocks
3. great deal comes from use of fertilizers
4. sometimes deposited in ocean sediments
5. long cycle that can be influenced by geological processes (uplift of marine sediments onto land)