Marine EcologyMarine Ecology

Chapter 10Chapter 10

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EcologyEcology

The study of the interactions between The study of the interactions between organisms and their environment.organisms and their environment.

Also studies how these interactions affect Also studies how these interactions affect the abundance and distribution of the abundance and distribution of populations.populations.

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How populations growHow populations grow

When conditions are right, populations will When conditions are right, populations will grow exponentially.grow exponentially.

That means, with unlimited food, shelter That means, with unlimited food, shelter and space- there is a population and space- there is a population explosion.explosion.

Abiotic (environmental) factors can reduce Abiotic (environmental) factors can reduce population growth.population growth.

Biotic factors (crowding, competition, Biotic factors (crowding, competition, disease) can affect population growth.disease) can affect population growth.

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Unchecked population growth in Unchecked population growth in dinoflagellatesdinoflagellates

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Exponential Exponential growthgrowth

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Explosions in the population of sea Explosions in the population of sea urchins can affect the entire ecosystem.urchins can affect the entire ecosystem.

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As the population increases, the amount of nutrients As the population increases, the amount of nutrients decreases.decreases.

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Carrying capacityCarrying capacity

The largest population that can be sustained The largest population that can be sustained by available resources.by available resources.

Limiting resource- a resource whose short Limiting resource- a resource whose short supply restricts population growth.supply restricts population growth.

Once the carrying capacity is reached, the Once the carrying capacity is reached, the population growth levels off.population growth levels off.

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CompetitionCompetition

Organisms constantly compete for Organisms constantly compete for resources.resources.

Competitive exclusion- when one species Competitive exclusion- when one species outcompetes another and eliminates it.outcompetes another and eliminates it.

Resource partitioning- sharing of resources Resource partitioning- sharing of resources by specialization.by specialization.

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Hermit crabs Hermit crabs compete for compete for

the best the best shells for shells for

protection.protection.

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Ecological niche- everyone plays a Ecological niche- everyone plays a partpart

Niche- an organisms’ role in the community.Niche- an organisms’ role in the community. bacteria recycle nutrients, predators bacteria recycle nutrients, predators

reduce population growth, etc.reduce population growth, etc. Predation- affects both the numbers of Predation- affects both the numbers of

predators and the number of prey. They predators and the number of prey. They rely on each other.rely on each other.

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This whale shark’s mouth is well adapted for taking This whale shark’s mouth is well adapted for taking in large volumes of water for filter feeding.in large volumes of water for filter feeding.

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PredationPredation

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The ‘Arms Race’The ‘Arms Race’

For every predator strategy, prey evolve For every predator strategy, prey evolve defenses to combat them.defenses to combat them.

Ex.- spines, nematocysts, lures, Ex.- spines, nematocysts, lures, camouflage.camouflage.

Natural Selection- favors the best predators Natural Selection- favors the best predators and also the prey that can get away!and also the prey that can get away!

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Symbiosis- one more time!Symbiosis- one more time! Commensalism- one organisms benefits, the Commensalism- one organisms benefits, the

other is ‘indifferent’.other is ‘indifferent’. ex- barnacles growing on the skin of ex- barnacles growing on the skin of

whales.whales. Mutualism- both species benefit.Mutualism- both species benefit. Ex.- coral and zooxanthellae.Ex.- coral and zooxanthellae. Parasitism- the host is harmed. Usually does Parasitism- the host is harmed. Usually does

not kill the host.not kill the host. Ex.- tapeworms in the gut of whales.Ex.- tapeworms in the gut of whales.

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More on symbiosisMore on symbiosis

Facultative symbiosis- both partners can Facultative symbiosis- both partners can survive without each other if they have to.survive without each other if they have to.

Obligate symbiosis- One or both partners Obligate symbiosis- One or both partners depend upon each other.depend upon each other.

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Energy flow through ecosystemsEnergy flow through ecosystems Trophic levels- feeding levels in the pyramid of Trophic levels- feeding levels in the pyramid of

energy. “Steps in the food chain”energy. “Steps in the food chain” Primary producers- phytoplankton, kelps and Primary producers- phytoplankton, kelps and

other seaweeds.other seaweeds. First level, or primary consumers- eat algae.First level, or primary consumers- eat algae. Second level, or secondary consumers- feed on Second level, or secondary consumers- feed on

the primary consumers.the primary consumers. Third level or tertiary consumers- feed on Third level or tertiary consumers- feed on

second level.second level. Top predators- animals like killer whalesTop predators- animals like killer whales

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Three step Three step food chain food chain

in in AntarcticaAntarctica

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Food webs- a more complete pictureFood webs- a more complete picture

Food webs show many different feeding Food webs show many different feeding relationships.relationships.

Many animals have more than one food Many animals have more than one food sourcesource

There may be many types of primary There may be many types of primary producers.producers.

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A marine A marine food webfood web

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Biomass and energyBiomass and energy

Each time an organism is eaten, only 10% Each time an organism is eaten, only 10% of its energy is passed on to the predator.of its energy is passed on to the predator.

90% is recycled by decomposers into the 90% is recycled by decomposers into the ecosystem.ecosystem.

1 million calories if energy in krill, only 1 million calories if energy in krill, only 100,000 are obtained by the whales.100,000 are obtained by the whales.

It takes a massive amount of primary It takes a massive amount of primary production to sustain those at higher production to sustain those at higher trophic levels.trophic levels.

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Measuring primary productivityMeasuring primary productivity

ProductivityProductivity- expressed as the amount of - expressed as the amount of carbon fixed under one square meter of carbon fixed under one square meter of sea surface in a day or a year.sea surface in a day or a year.

Includes phytoplankton and producers on Includes phytoplankton and producers on the ocean floor.the ocean floor.

Gross production-Gross production- total amount produced total amount produced through photosynthesis.through photosynthesis.

Net production-Net production- what is ‘left over’ for other what is ‘left over’ for other organisms to eat. organisms to eat.

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Productivity Productivity is a measure is a measure

of the of the amount of amount of

carbon carbon compounds compounds produced in produced in

the water the water column.column.

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Methods for Methods for measuring measuring

primary primary productivityproductivity

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A view of global primary productionA view of global primary production

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Nutrient cyclesNutrient cycles

Carbon cycle- Carbon cycle- Begins as carbon dioxide, is ‘fixed’ into Begins as carbon dioxide, is ‘fixed’ into

organic compounds by photosynthesis.organic compounds by photosynthesis. Passed to other consumers, is returned Passed to other consumers, is returned

to environment through respiration, to environment through respiration, excretion or decomposition.excretion or decomposition.

Bacteria and other decomposers return Bacteria and other decomposers return carbon to carbon dioxide dissolved in carbon to carbon dioxide dissolved in seawater.seawater.

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The The carbon carbon cycle in cycle in

the the oceanocean

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Nitrogen cycleNitrogen cycle

Nitrogen gas dissolves in ocean water.Nitrogen gas dissolves in ocean water. It is ‘fixed into nitrogen compounds by It is ‘fixed into nitrogen compounds by

bacteria, then absorbed by plankton.bacteria, then absorbed by plankton. Is passed on to consumers in the food web.Is passed on to consumers in the food web. Returns to nitrogen gas through death and Returns to nitrogen gas through death and

decomposition.decomposition.

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Nitrogen Nitrogen cycle in the cycle in the

ocean.ocean.

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Ecological Zones of the Marine Ecological Zones of the Marine Environment.Environment.

Classifying the lifestyles of marine life-Classifying the lifestyles of marine life- BenthosBenthos- organisms that live on the sea floor. - organisms that live on the sea floor.

Ex.- lobsters, sponges, crabs.Ex.- lobsters, sponges, crabs. PelagicPelagic- live in the water column. Two types:- live in the water column. Two types: NektonNekton- Pelagic free swimmers that can - Pelagic free swimmers that can

swim against a current. Ex. – most fish, sharks, swim against a current. Ex. – most fish, sharks, turtles, squid.turtles, squid.

PlanktonPlankton- any pelagic organism that is at - any pelagic organism that is at the mercy of ocean currents. Ex. Phytoplankton, the mercy of ocean currents. Ex. Phytoplankton, jellies, zooplankton.jellies, zooplankton.

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Classifying marine environments by Classifying marine environments by location- The benthic zones.location- The benthic zones.

Intertidal or littoral zone-Intertidal or littoral zone- between the tides. between the tides. Subtidal or Sublittoral zone-Subtidal or Sublittoral zone- Benthic area on Benthic area on

the continental shelf.the continental shelf. Deep sea floor-Deep sea floor- include the bathyl, abyssal, include the bathyl, abyssal,

and hadal zones.and hadal zones.

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Marine environments- the Pelagic Marine environments- the Pelagic zoneszones

Neritic zone-Neritic zone- pelagic environment above the pelagic environment above the continental shelf.continental shelf.

Oceanic zone-Oceanic zone- past the shelf break. Divided into past the shelf break. Divided into several ‘subzones’.several ‘subzones’.

EpipelagicEpipelagic- near the surface, first 100-200 - near the surface, first 100-200 meters. Most photosynthesis occurs here.meters. Most photosynthesis occurs here.

MesopelagicMesopelagic- the ‘twilight zone’. 200-- the ‘twilight zone’. 200-1000m deep1000m deep

Deep seaDeep sea – includes bathypelagic, – includes bathypelagic, abyssopelagic. Total darkness.abyssopelagic. Total darkness.

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Figure 10.22Figure 10.22