Life on the OceanLife on the Ocean There is a sub-discipline of the science of There is a sub-discipline of the science of

biology known as biology known as ECOLOGYECOLOGY. . Ecology is the study of the inter-relationships Ecology is the study of the inter-relationships

of organisms, of how they fit together in a of organisms, of how they fit together in a community.community.

what are the factors that interplay in the world what are the factors that interplay in the world marine organism live in. marine organism live in.

What other organisms do they live with? What What other organisms do they live with? What climates do they prefer?climates do they prefer?

Each community has its share of each Each community has its share of each trophic leveltrophic level::• producersproducers (plants and certain bacteria) (plants and certain bacteria) • herbivoresherbivores • primary primary carnivorescarnivores • secondary carnivoressecondary carnivores • tertiary carnivores, and so on.tertiary carnivores, and so on.

The The 10% Rule10% Rule :For every 100 pounds of plants in an area, :For every 100 pounds of plants in an area,

there will be 10 pounds of herbivores and 1 there will be 10 pounds of herbivores and 1 pound of primary carnivores, 0.1 pound of pound of primary carnivores, 0.1 pound of secondary carnivore, and so on. secondary carnivore, and so on.

Think about how much plant material is Think about how much plant material is needed to power a sperm whale, keeping in needed to power a sperm whale, keeping in mind how tiny the one-celled algae are, and mind how tiny the one-celled algae are, and how many steps there are in the food chain how many steps there are in the food chain between the plants and the whales!!!between the plants and the whales!!!

It's A LOT. It's A LOT.

In the diagram above, if 'kg' [kilogram] is too In the diagram above, if 'kg' [kilogram] is too much for you, substitute 'pound'. much for you, substitute 'pound'.

It doesn't matter, the proportions are what count.It doesn't matter, the proportions are what count. For every kilogram of tuna in a community, there For every kilogram of tuna in a community, there

must be 10,000 kg of plants to support it. must be 10,000 kg of plants to support it. Tuna are typically 400 kg!!!! 400 x 10,000 = Tuna are typically 400 kg!!!! 400 x 10,000 =

4,000,000 kg of plants!! 4 million kilos of plants-4,000,000 kg of plants!! 4 million kilos of plants-over 8 million pounds of plants-to support 1 over 8 million pounds of plants-to support 1 good-size tuna! good-size tuna!

This is why we need to This is why we need to pay attention to what pay attention to what is happening with our producersis happening with our producers (like the rain (like the rain forests) and fellow herbivores and carnivores.forests) and fellow herbivores and carnivores.

If the lower part of the food web (producers) If the lower part of the food web (producers) is disturbed, and lots of organisms in that is disturbed, and lots of organisms in that trophic level die off, the top of the pyramid trophic level die off, the top of the pyramid tumbles. tumbles.

Sometimes we humans are at the top of the Sometimes we humans are at the top of the pyramid, particularly when we eat fish.pyramid, particularly when we eat fish.

Plant ProductivityPlant Productivity We can see that plants play the most important We can see that plants play the most important

role in understanding what animals live where. role in understanding what animals live where. If we want to know where the animals are, it If we want to know where the animals are, it

would help to know where the plants are and would help to know where the plants are and how how productiveproductive they are. they are.

In addition, these plants are big players in In addition, these plants are big players in regulating levels of COregulating levels of CO22 in the oceans and in the oceans and atmosphere. atmosphere.

So where ARE the plants in the oceans? So where ARE the plants in the oceans?

The answer is, The answer is, it depends on how we it depends on how we measure them.measure them.

How do you measure how much plant How do you measure how much plant material is out there, and how do you material is out there, and how do you measure how active and productive they are?measure how active and productive they are?

We go about measuring their presence and We go about measuring their presence and abundance in various ways, none of which abundance in various ways, none of which are 'perfect' (each has advantages and are 'perfect' (each has advantages and disadvantages)disadvantages)

Take a fine mesh Take a fine mesh netnet and drag it through the water and drag it through the water

(the net is called a 'seine', pronounced 'sane'). (the net is called a 'seine', pronounced 'sane'). Then examine what you've caught in the net, weigh Then examine what you've caught in the net, weigh

it, and estimate the volume of water it came from. it, and estimate the volume of water it came from. An An advantageadvantage to this method is that you can open to this method is that you can open

the net at a specific water depth, so we can the net at a specific water depth, so we can measure plant measure plant abundance with depthabundance with depth

Another Another advantageadvantage is that you can identify and is that you can identify and count numbers of count numbers of speciesspecies

A disadvantage is that you do A disadvantage is that you do notnot know know if the plants are if the plants are actively actively photosynthesizingphotosynthesizing or are in a seasonal or are in a seasonal dormancy dormancy

On the left, what gets caught in the net. On the left, what gets caught in the net. On the right, the net being deployed. On the right, the net being deployed. Recognize anything on the left?Recognize anything on the left?

Measure COMeasure CO22 and O and O22 levels in the water levels in the water an an advantageadvantage to this method is that you to this method is that you

get an estimate of plant get an estimate of plant productivityproductivity you can also do this at a specific you can also do this at a specific water water

depthdepth you you don't knowdon't know what types, what what types, what

speciesspecies of plants are doing the activity, of plants are doing the activity, howeverhowever

There are several ways to measure There are several ways to measure oxygen and carbon dioxide levels. oxygen and carbon dioxide levels.

A series of bottles are lowered into the A series of bottles are lowered into the ocean and opened at a known depth. ocean and opened at a known depth.

At each depth, there are two bottles: At each depth, there are two bottles: one that lets in light (clear bottle), and one that lets in light (clear bottle), and one that doesn't (opaque bottle).one that doesn't (opaque bottle).

Plants can photosynthesize through the clear Plants can photosynthesize through the clear bottle, but not the opaque one. bottle, but not the opaque one.

After a while the bottles are brought back to After a while the bottles are brought back to the ship and the oxygen levels are measured the ship and the oxygen levels are measured in each pair. in each pair.

The oxygen level in the clear bottle minus the The oxygen level in the clear bottle minus the oxygen level in the opaque bottle = the oxygen level in the opaque bottle = the amount of oxygen produced by the plants in amount of oxygen produced by the plants in the amount of time the bottles were in the the amount of time the bottles were in the water.water.

Can you see why just measuring oxygen level Can you see why just measuring oxygen level doesn't tell you how active the plants are?doesn't tell you how active the plants are?

measure the levels of measure the levels of chlorophyllchlorophyll in the in the surface waters of the ocean using a special surface waters of the ocean using a special satellite designed for that purpose: satellite designed for that purpose:

the Sea-viewing Wide Field-of-view Sensor the Sea-viewing Wide Field-of-view Sensor (SeaWiFS for short). (SeaWiFS for short).

The The more phytoplankton present, the greater more phytoplankton present, the greater the concentration of plant pigments and the the concentration of plant pigments and the greener the watergreener the water. .

SeaWIFs measures color of the water. SeaWIFs measures color of the water. disadvantagesdisadvantages are that are that only the top 2 metersonly the top 2 meters

of the oceans are 'seen' by the satellite, of the oceans are 'seen' by the satellite, andand again, you again, you don't knowdon't know if the plants are if the plants are

active or dormantactive or dormant But the But the big advantagebig advantage is that you can see the is that you can see the

whole globe about every 48 hourswhole globe about every 48 hours. .

So data collected from ships (using nets or So data collected from ships (using nets or measuring Omeasuring O22/CO/CO22 levels) and satellites gives levels) and satellites gives us a snapshot of what phytoplankton us a snapshot of what phytoplankton productivity is like over the oceans.productivity is like over the oceans.

In general, productivity is highest where In general, productivity is highest where upwellingupwelling occurs (as you might expect) occurs (as you might expect)

under under eastern boundary currentseastern boundary currents in areas of in areas of current divergencecurrent divergence

in in coastal areascoastal areas where rivers bring where rivers bring

nutrients to the oceannutrients to the ocean in in warm, tropical waterswarm, tropical waters in the in the polar regionspolar regions where where upwellingupwelling

occurs, but occurs, but this productivity is seasonalthis productivity is seasonal. . These areas bloom in the summer, and These areas bloom in the summer, and

are nearly nonproductive as the plants are nearly nonproductive as the plants go dormant for the winter.go dormant for the winter.

Dormancy at one pole occurs while Dormancy at one pole occurs while there is a bloom at the other. there is a bloom at the other.

This is why lots of animals migrate over This is why lots of animals migrate over the oceans-visiting Alaska and the oceans-visiting Alaska and Greenland in the northern summer, and Greenland in the northern summer, and Patagonia (South America) and Patagonia (South America) and Antarctica in the southern summer Antarctica in the southern summer

Another Producer!Another Producer! We've recently discovered (ok, 1977) a We've recently discovered (ok, 1977) a

new ecosystem that does not depend new ecosystem that does not depend on sunlight for energy, on sunlight for energy,

it depends on the heat energy released it depends on the heat energy released at black and white smokers and hot at black and white smokers and hot springs in the deep, dark parts of the springs in the deep, dark parts of the ocean near seafloor spreading centers ocean near seafloor spreading centers and hotspots. and hotspots.

The producers for this ecosystem are The producers for this ecosystem are bacteriabacteria called called chemosynthesizerschemosynthesizers. .

Only a tiny percentage of life in the Only a tiny percentage of life in the oceans (and none on land) relies on oceans (and none on land) relies on chemosynthesizers for primary food chemosynthesizers for primary food production, but it's pretty interesting, production, but it's pretty interesting, nonetheless. nonetheless.

it's hard to get your samples back to the lab in it's hard to get your samples back to the lab in one piece; the animals down there are built to one piece; the animals down there are built to withstand the huge pressures of great water withstand the huge pressures of great water depths, and when they are brought to the depths, and when they are brought to the surface, where the pressure is low in surface, where the pressure is low in comparison, they blow up.comparison, they blow up.

they must smell awful; the whole system is they must smell awful; the whole system is permeated with hydrogen sulfide, which is the permeated with hydrogen sulfide, which is the smell of rotten eggssmell of rotten eggs

We can define each part of the ocean on the We can define each part of the ocean on the basis of the following:basis of the following:

1.1. temperaturetemperature 2.2. amount of lightamount of light 3.3. currentscurrents 4.4. salinitysalinity 5.5. nutrient supplynutrient supply 6.6. water depthwater depth 7.7. nature of the sediment on the bottomnature of the sediment on the bottom

TEMPERATURETEMPERATURE The most important,The most important, for all organisms, not just for all organisms, not just

the coral. the coral. Most oceanic organisms are cold-blooded Most oceanic organisms are cold-blooded

((poikilothermicpoikilothermic).). they cannot regulate their internal temp. they cannot regulate their internal temp. Their body temperature is near the temperature Their body temperature is near the temperature

of the water they live in. of the water they live in. Animals that can maintain a warmer-than-Animals that can maintain a warmer-than-

surroundings internal temperature are surroundings internal temperature are homeothermichomeothermic. .

Only organisms that Only organisms that left the sea for land left the sea for land or freshwater and or freshwater and returned to the sea returned to the sea are homeothermic: are homeothermic:

Marine mammalsMarine mammals Big fish like marlin, Big fish like marlin,

tuna, and tarpon are tuna, and tarpon are homeothermic.homeothermic.

METABOLISMMETABOLISM The process by which all organisms extract The process by which all organisms extract

energy from food, is a chemical reaction that energy from food, is a chemical reaction that is strongly influenced by temperature. is strongly influenced by temperature.

The warmer the temperature, the faster The warmer the temperature, the faster metabolism will bemetabolism will be. .

Organisms that normally live in cooler waters Organisms that normally live in cooler waters may burn themselves up if taken to warmer may burn themselves up if taken to warmer water. water.

And organisms that normally live in warm And organisms that normally live in warm waters won't have enough energy to power waters won't have enough energy to power their vital organs, like the brain and heart, if their vital organs, like the brain and heart, if they move to cooler waters. they move to cooler waters.

Organisms living in warmer waters tend to Organisms living in warmer waters tend to grow faster, have a faster heartbeat, grow faster, have a faster heartbeat, reproduce more rapidly, swim more swiftly, reproduce more rapidly, swim more swiftly, and live shorter lives than those living in and live shorter lives than those living in cooler waters.cooler waters.

Remember, AMOUNT OF DISSOLVED Remember, AMOUNT OF DISSOLVED GAS in the ocean is also determined by GAS in the ocean is also determined by temperature. temperature.

Fast swimmers such as salmon, trout, Fast swimmers such as salmon, trout, and pike need to live in cold waters and pike need to live in cold waters because their oxygen demand is high. because their oxygen demand is high.

AMOUNT OF LIGHTAMOUNT OF LIGHT Determines how productive plants can be. Determines how productive plants can be. determined by determined by water depthwater depth and and water turbiditywater turbidity

(how much sediment is suspended in the water). (how much sediment is suspended in the water). Light is composed of different colors and most Light is composed of different colors and most

light penetrates only about 100 m into the water, light penetrates only about 100 m into the water, lless if there is much suspended sediment in the ess if there is much suspended sediment in the

waterwater Blue light can penetrate deepest, to about 450 m. Blue light can penetrate deepest, to about 450 m.

Green light can Green light can penetrate to about penetrate to about 300 m water depth, 300 m water depth, but plants do not but plants do not use green light-they use green light-they reflectreflect green light. green light.

This is why plants This is why plants look green to us. look green to us.

The depth to which light can penetrate The depth to which light can penetrate defines an important area to plants: the defines an important area to plants: the PHOTIC ZONEPHOTIC ZONE. .

Plants have enough light to Plants have enough light to photosynthesize in the photic zone. photosynthesize in the photic zone.

They can't photosynthesize in deeper They can't photosynthesize in deeper water.water.

CURRENTSCURRENTS determines how successful filter-determines how successful filter-

feeders can be.feeders can be. They need some current to bring food They need some current to bring food

particles their way, but not so much particles their way, but not so much current that it just blows the food past. current that it just blows the food past.

Currents can drag plankton along to Currents can drag plankton along to colder or warmer waters than the colder or warmer waters than the plankton prefer. plankton prefer.

    SALINITYSALINITY We are all composed of cells that are We are all composed of cells that are

surrounded by a surrounded by a membranemembrane. . That membrane can allow water to pass That membrane can allow water to pass

through it readily, but not salt. through it readily, but not salt. An organism's body fluids must be the same An organism's body fluids must be the same

salinity as seawater, or the organism needs salinity as seawater, or the organism needs to exert energy to either keep water in its to exert energy to either keep water in its body, or keep water out.body, or keep water out.

The process The process whereby water whereby water moves across the moves across the membrane but salt membrane but salt doesn't is called doesn't is called OSMOSIS (fig. OSMOSIS (fig. 13.15-16)13.15-16)

If an organism is If an organism is lessless salty than salty than seawater, water from the organism's seawater, water from the organism's body moves out (to increase its salinity).body moves out (to increase its salinity).

The organism will The organism will dehydratedehydrate if it doesn't if it doesn't actively drink water and get rid of actively drink water and get rid of excess salt that comes from drinking excess salt that comes from drinking seawater.seawater.

If an organism is If an organism is moremore salty than salty than seawater, water from the ocean moves seawater, water from the ocean moves into the organism's body and it into the organism's body and it blows blows upup. .

For higher marine organisms, such as For higher marine organisms, such as the arthropods and chordates, the the arthropods and chordates, the problem is the former: we are slightly problem is the former: we are slightly less salty than seawater.less salty than seawater.

A marine fishA marine fish Its salinity is only 18 Its salinity is only 18

parts per thousand. parts per thousand. It loses water by osmosis It loses water by osmosis

to increase its salinity, to increase its salinity, but gains it by drinking.but gains it by drinking.

However, seawater is too However, seawater is too salty for it, so it secretes salty for it, so it secretes salt via the gills, and salt via the gills, and produces hardly any produces hardly any urine. urine.

A fresh water fishA fresh water fish Its salinity is higher Its salinity is higher

than the environment. than the environment. It gains water by It gains water by

osmosis decreasing osmosis decreasing its salinity, avoids its salinity, avoids drinking water.drinking water.

However, fresh water However, fresh water moves in, so it moves in, so it produces copious produces copious urine. urine.

NUTRIENT SUPPLYNUTRIENT SUPPLY Determines how abundant life can be. Determines how abundant life can be. include include organic compoundsorganic compounds such as proteins, such as proteins,

vitamins, and vitamins, and inorganicinorganic compounds, called compounds, called 'minerals', such as calcium, magnesium, selenium, 'minerals', such as calcium, magnesium, selenium, etc. etc.

Nutrients for Nutrients for plantsplants are are all inorganicall inorganic and include and include nitrogen, phosphorus, potassium, and a host of nitrogen, phosphorus, potassium, and a host of others. others.

The nutrient supply to plants is the more important. The nutrient supply to plants is the more important. Without plants, there can be no nutrients for the Without plants, there can be no nutrients for the animals. animals.

Nutrients for plants come from one of Nutrients for plants come from one of two places: two places:

1.1. runoff from continents products of runoff from continents products of chemical weathering. chemical weathering.

2.2. upwellingupwelling from the sea floor. from the sea floor.

Where upwelling Where upwelling occurs?occurs?

1.1. divergent ocean divergent ocean currentscurrents

2.2. eastern boundary eastern boundary currentscurrents

    WATER DEPTHWATER DEPTH determines the determines the amount of pressureamount of pressure an an

organism experiences and the organism experiences and the amount of amount of lightlight it has. it has.

Water depth defines Water depth defines ocean provincesocean provinces.. A province is an area where we expect to find A province is an area where we expect to find

similar plants and animals, depending on similar plants and animals, depending on other environmental factors (temperature, other environmental factors (temperature, current, salinity, nutrient supply)(f.13.19)current, salinity, nutrient supply)(f.13.19)

Provinces have different names Provinces have different names depending on whether we are depending on whether we are considering benthonic organisms or considering benthonic organisms or nektonic and planktonic organisms. nektonic and planktonic organisms.

Pelagic ProvincesPelagic Provinces– (nekton, plankton)(nekton, plankton)

Benthic ProvincesBenthic Provinces– epipelagicepipelagic 0-200 m 0-200 m– littorallittoral intertidalintertidal ( (foreshoreforeshore))– mesopelagicmesopelagic 200-1000 m 200-1000 m

– sublittoralsublittoral 0-200 m (continental shelf) 0-200 m (continental shelf)– bathypelagicbathypelagic 1000-4000 m 1000-4000 m– bathyalbathyal 200-4000 m (continental slope and 200-4000 m (continental slope and

rise; mid-ocean ridges)rise; mid-ocean ridges)

– abyssopelagicabyssopelagic 4000-6000 m 4000-6000 m– abyssalabyssal 4000-6000 m (abyssal plains) 4000-6000 m (abyssal plains)– hadalpelagichadalpelagic >6,000 m >6,000 m– hadalhadal >6,000 m (trenches) >6,000 m (trenches)

    Most plankton live in the epipelagic, photic Most plankton live in the epipelagic, photic

zone.zone. Most light penetrates into the epipelagic and Most light penetrates into the epipelagic and

littoral to sublittoral zones. littoral to sublittoral zones. Some whales and giant squid live in the Some whales and giant squid live in the

mesopelagic and even into the top of the mesopelagic and even into the top of the bathypelagic province. bathypelagic province.

We still have so much to learn about life in We still have so much to learn about life in the meso-, bathy- and abyssopelagic realms!the meso-, bathy- and abyssopelagic realms!

Nature of the bottomNature of the bottom sediment (sandy, muddy, carbonate), or sediment (sandy, muddy, carbonate), or

rocky. Particularly important to the rocky. Particularly important to the benthos.benthos.

All of the physical factors interplayAll of the physical factors interplay. . If the sun warms up water at the If the sun warms up water at the

equator, water may evaporate from the equator, water may evaporate from the ocean and raise the salinity. ocean and raise the salinity.

Dissolved oxygen levels will go down, Dissolved oxygen levels will go down, but plant growth will speed up which but plant growth will speed up which can raise oxygen levels back up during can raise oxygen levels back up during the day, but drive them down again at the day, but drive them down again at night. night.

All the physical factors together make up a All the physical factors together make up a

provinceprovince. . Each province of the ocean then has a unique Each province of the ocean then has a unique

set of plants and animals that are adapted to set of plants and animals that are adapted to that province. that province.

The set of plants and animals is a The set of plants and animals is a communitycommunity. . A community is all of the organisms living in A community is all of the organisms living in

the same environment (province) and the same environment (province) and interacting with one another.interacting with one another.

In the ocean, we see that animals and In the ocean, we see that animals and plants fit into one of four basic plants fit into one of four basic lifestyleslifestyles::

1.1. planktonicplanktonic 2.2. nektonicnektonic 3.3. nekto-benthonicnekto-benthonic 4.4. benthonicbenthonic

Each Each communitycommunity has its share of has its share of plankton, nekton, and benthos. plankton, nekton, and benthos.

The The really defining members of most really defining members of most communitiescommunities would be the would be the BENTHOSBENTHOS because some nektonic organisms can because some nektonic organisms can swim into an area and swim out of it swim into an area and swim out of it again. again.

So a particular So a particular communitycommunity exists because it exists because it

shares the following characteristics: shares the following characteristics: • physicalphysical characteristics of the characteristics of the waterwater

temperaturetemperature amount of lightamount of light vigor of the currentsvigor of the currents salinitysalinity nutrient supplynutrient supply water depthwater depth

• characteristics of the characteristics of the sea floorsea floor the benthos live on or in the benthos live on or in (sandy, muddy, rocky, carbonate) and (sandy, muddy, rocky, carbonate) and

• the types of the types of animalsanimals and and plantsplants within each.    within each.