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Chapter 15Chapter 15Life Near the
SurfaceLife Near the
Surface
Vast open sea – pelagic realmContains almost all of the
liquid water on earth
Vast open sea – pelagic realmContains almost all of the
liquid water on earth
How the Open Sea Effects You
How the Open Sea Effects You
Regulates our climateConditions our atmosphereProvides food and many
resources
Regulates our climateConditions our atmosphereProvides food and many
resources
Life in the PelagicLife in the Pelagic
Pelagic organisms live suspended in their liquid medium
Lacks the solid physical structure provided by the bottom
No place for attachment, no bottom for burrowing, nothing to hide behind
Pelagic organisms live suspended in their liquid medium
Lacks the solid physical structure provided by the bottom
No place for attachment, no bottom for burrowing, nothing to hide behind
EpipelagicEpipelagic
Upper pelagicZone from the surface down to a
given depth commonly 200 m (650 ft)
Warmest Best litSimilar to the photic zone (area
where photosynthesis can occur)
Upper pelagicZone from the surface down to a
given depth commonly 200 m (650 ft)
Warmest Best litSimilar to the photic zone (area
where photosynthesis can occur)
I. Pelagic 1. Epipelagic 2. Mesopelagic 3. Bathypelagic 4. Abyssopelagic
II. Benthic 5. Littoral, Sub-littoral 6. Bathyal 7. Abyssal 8. Ultra-abyssal
Two Main ComponentsTwo Main Components
1.Coastal or Nertic – epipelagic waters that lie over the continental shelf
Lies close to shoreSupports most of the world’s
marine fisheries production
1.Coastal or Nertic – epipelagic waters that lie over the continental shelf
Lies close to shoreSupports most of the world’s
marine fisheries production
2.Oceanic partWaters beyond the continental shelf
2.Oceanic partWaters beyond the continental shelf
The Organisms of the Epipelagic
The Organisms of the Epipelagic
The Pelagic RealmThe Pelagic Realm
Fueled by solar energy captured in photosynthesis
Nearly all primary production takes place within the epiplagic system itself
Gets almost no external input of organic matter
Supplies food to other communities
Fueled by solar energy captured in photosynthesis
Nearly all primary production takes place within the epiplagic system itself
Gets almost no external input of organic matter
Supplies food to other communities
Lacks deposit feedersSuspension feeders are very
commonThere are also many large
predators like fishes, squids and marine mammals
Lacks deposit feedersSuspension feeders are very
commonThere are also many large
predators like fishes, squids and marine mammals
The Plankton: A New
Understanding
The Plankton: A New
Understanding
Scientist used to study plankton by catching them in tow nets
This practice limited what organisms were caught
Scientist used to study plankton by catching them in tow nets
This practice limited what organisms were caught
Recent developments in collecting plankton have lead to the discovery of many new groups of plankton and have changed how the plankton interactions are currently looked at
Recent developments in collecting plankton have lead to the discovery of many new groups of plankton and have changed how the plankton interactions are currently looked at
Plankton can be grouped based on their size
Plankton can be grouped based on their size
Picoplankton – smallestNanoplanktonMicroplanktonMesoplanktonMacroplanktonMegaplankton – largest
Picoplankton – smallestNanoplanktonMicroplanktonMesoplanktonMacroplanktonMegaplankton – largest
Phytoplankton – perform photosynthesis
Zooplankton – cannot perform photosynthesis - heterotrophs
Phytoplankton – perform photosynthesis
Zooplankton – cannot perform photosynthesis - heterotrophs
Phytoplankton – Major Groups
Phytoplankton – Major Groups
Net Plankton (Micro, Meso, Macro)
Net Plankton (Micro, Meso, Macro)
Diatoms – found everywhere – important primary producers
Dinoflagellates found everywhere, most common in warm waters – common red tide organisms
Diatoms – found everywhere – important primary producers
Dinoflagellates found everywhere, most common in warm waters – common red tide organisms
Diatoms
Dinoflagellates
Colonial cyanobacteria (Trichodesmium) – mainly tropical – can fix atmospheric nitrogen – causes red tides in the Red Sea
Colonial cyanobacteria (Trichodesmium) – mainly tropical – can fix atmospheric nitrogen – causes red tides in the Red Sea
NanoplanktonNanoplankton
Coccolithophorids – important primary producers in nutrient poor waters
Cryptophytes – very important primary producers
Silicoflagellates – sometimes form blooms
Coccolithophorids – important primary producers in nutrient poor waters
Cryptophytes – very important primary producers
Silicoflagellates – sometimes form blooms
CoccolithophoridsCoccolithophorids
PicoplanktonPicoplankton
Unicellular cyanobacteria (Prochlorococcus) dominant primary producers, especially in nutrient poor water
Various protists – presence of many groups recently discovered
Unicellular cyanobacteria (Prochlorococcus) dominant primary producers, especially in nutrient poor water
Various protists – presence of many groups recently discovered
ZooPlanktonZooPlankton
Phytoplankton form the base of the food web
Solar energy that they capture and store in organic matter is passed on to the other creatures of the epipelagic from minute zooplankton to gigantic whales
Herbivores eat phytoplankton
Phytoplankton form the base of the food web
Solar energy that they capture and store in organic matter is passed on to the other creatures of the epipelagic from minute zooplankton to gigantic whales
Herbivores eat phytoplankton
Zooplankton are by far the most important herbivores in the epipelagic
Very few zooplankton are strict herbivores – will eat other zooplankton
Most zooplankton species are primarily carnivorous and hardly eat phytoplankton at all
Zooplankton are by far the most important herbivores in the epipelagic
Very few zooplankton are strict herbivores – will eat other zooplankton
Most zooplankton species are primarily carnivorous and hardly eat phytoplankton at all
Protozoan ZooplanktonProtozoan Zooplankton
Protozoans can catch tiny picoplankton and nanoplankton
Without protozoans, much of the primary production in the epipelagic would go unutilized
Flagellates, Ciliates, Foraminiferans, Radiolarians
Protozoans can catch tiny picoplankton and nanoplankton
Without protozoans, much of the primary production in the epipelagic would go unutilized
Flagellates, Ciliates, Foraminiferans, Radiolarians
Foraminiferans
Radiolarians
CopepodsCopepods
Small crustaceansDominate the net zooplanktonMost abundant members of
the net zooplankton practically everywhere in the ocean – 70% or more of the community
Major carnivores
Small crustaceansDominate the net zooplanktonMost abundant members of
the net zooplankton practically everywhere in the ocean – 70% or more of the community
Major carnivores
Copepods
Other Crustaceans – Shrimp-Like Krill
Other Crustaceans – Shrimp-Like Krill
Not as abundant as copepods but often aggregate into huge dense swarms
Dominate the plankton in the polar seas
Not as abundant as copepods but often aggregate into huge dense swarms
Dominate the plankton in the polar seas
Efficient filter feeders – diatoms are a favorite food, also eat detritus
Relatively big – up to 6 cmEaten by fishes, seabirds,
great whales
Efficient filter feeders – diatoms are a favorite food, also eat detritus
Relatively big – up to 6 cmEaten by fishes, seabirds,
great whales
Krill
Non-Crustacean Zooplantkon
Non-Crustacean Zooplantkon
Salps – transparent, planktonic herbivores – filter out plankton by pumping water through a sieve-like sac or a fine mucus net
Larvaceans – float inside a house they make of mucus – beat tail to move water through the house – food particles are caught in a complicated mucus net that is inside the house
Salps – transparent, planktonic herbivores – filter out plankton by pumping water through a sieve-like sac or a fine mucus net
Larvaceans – float inside a house they make of mucus – beat tail to move water through the house – food particles are caught in a complicated mucus net that is inside the house
Pteropods – mollusks – small snails that have a foot that has been modified to form a pair of wings that they flap to stay afloat
Arrow Worms or chaetognaths – extremely important predators in the zooplankton – feed mostly on copepods
Pteropods – mollusks – small snails that have a foot that has been modified to form a pair of wings that they flap to stay afloat
Arrow Worms or chaetognaths – extremely important predators in the zooplankton – feed mostly on copepods
Jellyfish and siphonophores – large, weak swimmers that drift with the currents – carnivore
Jellyfish and siphonophores – large, weak swimmers that drift with the currents – carnivore
HoloplanktonHoloplankton
Spend their whole lives as plankton
Spend their whole lives as plankton
MeroplanktonMeroplankton
Many fish and invertebrates have planktonic larvae
Temporary members of the plankton
Small larvae feed on phytoplankton
Many fish and invertebrates have planktonic larvae
Temporary members of the plankton
Small larvae feed on phytoplankton
Larger larvae feed on zooplankton
Larvae can grow while in the plankton and change trophic levels
Larger larvae feed on zooplankton
Larvae can grow while in the plankton and change trophic levels
The NektonThe Nekton
Large strong swimmersFishes, marine mammals,
squids, turtles, sea snakes, penguins
Carnivorous
Large strong swimmersFishes, marine mammals,
squids, turtles, sea snakes, penguins
Carnivorous
Planktivorous nekton – eat plankton – include herrings, sardines and anchovies, whale shark and the basking shark
Planktivorous nekton – eat plankton – include herrings, sardines and anchovies, whale shark and the basking shark
Herring
AnchoviesSardines
Most species of nekton eat other nekton
Fishes, squids and large crustaceans are the main foods
Epipelagic predators are not fussy, just need to be the right size
Most species of nekton eat other nekton
Fishes, squids and large crustaceans are the main foods
Epipelagic predators are not fussy, just need to be the right size
In general the larger the predator the larger the
prey
In general the larger the predator the larger the
preyHerrings (small fish) –
zooplanktonSperm whale largest of
nekton – giant squid 10 m (33 ft long)
Herrings (small fish) – zooplankton
Sperm whale largest of nekton – giant squid 10 m (33 ft long)
Living in the EpipelagicLiving in the Epipelagic
Demands of the environment cause organisms to have certain adaptations
Two main problemsNeed to stay in the epipelagic
zoneNeed to eat and avoid being
eaten
Demands of the environment cause organisms to have certain adaptations
Two main problemsNeed to stay in the epipelagic
zoneNeed to eat and avoid being
eaten
Staying AfloatStaying Afloat
Cells and tissues are denser than water – naturally sink
Shells and skeletons are even more dense
Phytoplankton need to stay for sun and the others need to stay so they can get prey
Cells and tissues are denser than water – naturally sink
Shells and skeletons are even more dense
Phytoplankton need to stay for sun and the others need to stay so they can get prey
How to stay afloat if you can not swim
How to stay afloat if you can not swim
Increase the water resistance so that you sink slower
Make yourself more buoyant
Increase the water resistance so that you sink slower
Make yourself more buoyant
Increased ResistanceIncreased Resistance
Drag – resistance to movement through water or any other medium
Small organisms – drag mostly depends on surface area – higher the surface area the slower the organism sinks – reason plankton are so small
Drag – resistance to movement through water or any other medium
Small organisms – drag mostly depends on surface area – higher the surface area the slower the organism sinks – reason plankton are so small
Shape influences surface area – parachute shape slows sinking (jellyfish)
Flat shapes slow sinkingLong projections or spines
increase surface area and therefore decrease the rate of sinking
Forming chains slows sinking
Shape influences surface area – parachute shape slows sinking (jellyfish)
Flat shapes slow sinkingLong projections or spines
increase surface area and therefore decrease the rate of sinking
Forming chains slows sinking
Swimming organisms rarely have spines as this would increase water resistance and make swimming harder
They generally have adaptations that reduce drag
Swimming organisms rarely have spines as this would increase water resistance and make swimming harder
They generally have adaptations that reduce drag
Increase BuoyancyIncrease Buoyancy
Reduces the tendency to sinkStore lipids (Oils or fats)Lipids are less dense so they
tend to floatDiatoms, copepod and fish
eggs contain a drop of oilMany adult fish store lipids –
especially sharks and tuna
Reduces the tendency to sinkStore lipids (Oils or fats)Lipids are less dense so they
tend to floatDiatoms, copepod and fish
eggs contain a drop of oilMany adult fish store lipids –
especially sharks and tuna
Whales, seals and other marine mammals have a great deal of buoyant fat in a thick layer of blubber under the skin
Pocket of gas is another adaptation
Whales, seals and other marine mammals have a great deal of buoyant fat in a thick layer of blubber under the skin
Pocket of gas is another adaptation
Bony fish have swim bladders – disadvantage – gases expand and contract as the fish moves in the water column
Bony fish have swim bladders – disadvantage – gases expand and contract as the fish moves in the water column
The FloatersThe Floaters
Neuston – organisms that live right at the sea surface but remain underwater
Pleuston – organisms whose bodies project through the sea surface into the air
Most common method is to have a gas-filled structure
Neuston – organisms that live right at the sea surface but remain underwater
Pleuston – organisms whose bodies project through the sea surface into the air
Most common method is to have a gas-filled structure
By-the-wind-sailor – (Velella) – colonial jellyfish-like cnidarian that is specialized as a float
Portuguese man-of-war (Physalia) – powerful sting – part of the colony acts as a sail
Violet shell (Janthina)- makes a rafts of mucus filled with bubbles from which it hangs upside down
By-the-wind-sailor – (Velella) – colonial jellyfish-like cnidarian that is specialized as a float
Portuguese man-of-war (Physalia) – powerful sting – part of the colony acts as a sail
Violet shell (Janthina)- makes a rafts of mucus filled with bubbles from which it hangs upside down
VelellaVelella
Physalia
Janthina
Predators and their Prey
Predators and their Prey
Many of the adaptations of epipelagic animals are related to their need to find food and at the same time avoid being eaten
Many of the adaptations of epipelagic animals are related to their need to find food and at the same time avoid being eaten
Sense OrgansSense Organs
Highly developedVision is important – many have
good eyesightVision is especially important to
the nekton because there are no solid structures to avoid concealment
Highly developedVision is important – many have
good eyesightVision is especially important to
the nekton because there are no solid structures to avoid concealment
Lateral line – remote sensing system that sense vibrations in the water – used to stay with school mates and detect predators
Lateral line – remote sensing system that sense vibrations in the water – used to stay with school mates and detect predators
Coloring and Camouflage
Coloring and Camouflage
Protective coloration or camouflage
Nearly universal among epipelagic organisms that are large enough to be seen
One way – transparent – jellyfish, salps, larvaceans, comb jellies
Protective coloration or camouflage
Nearly universal among epipelagic organisms that are large enough to be seen
One way – transparent – jellyfish, salps, larvaceans, comb jellies
Countershading – dorsal surface (back) is dark usually green, blue or black and the belly (ventral surface) is white or silver
Looking down – ocean depths are dark blue and it is hard to see the prey
Looking up – bright light is filtered down and it is hard to see the prey
Countershading – dorsal surface (back) is dark usually green, blue or black and the belly (ventral surface) is white or silver
Looking down – ocean depths are dark blue and it is hard to see the prey
Looking up – bright light is filtered down and it is hard to see the prey
Laterally compressed bodies are also common – reduce the size of the silhouette
Laterally compressed bodies are also common – reduce the size of the silhouette
Silvery sides – reflect light – help to blend in
Vertical bars or irregular patterns – help to break up their outline in the dappled under water light
Silvery sides – reflect light – help to blend in
Vertical bars or irregular patterns – help to break up their outline in the dappled under water light
Swimming: The Need for Speed
Swimming: The Need for Speed
Whether the prey gets away or the predator gets a meal depends on which swims faster
Emphasis is on sheer speedEpipelagic contains the
worlds most powerful swimmers
Whether the prey gets away or the predator gets a meal depends on which swims faster
Emphasis is on sheer speedEpipelagic contains the
worlds most powerful swimmers
Practically all epipelagic nekton have streamlined bodies that make swimming easier & more efficient
Do not have features that increase resistance (like spines, bulging eyes)
Practically all epipelagic nekton have streamlined bodies that make swimming easier & more efficient
Do not have features that increase resistance (like spines, bulging eyes)
Laterally compressed bodies are also common – reduce the size of the silhouette
Firm and Muscular
Laterally compressed bodies are also common – reduce the size of the silhouette
Firm and Muscular
Force is delivered mainly by the tail
The tail is high and narrowFins tend to be stiff – provides
maneuverability and lift
Force is delivered mainly by the tail
The tail is high and narrowFins tend to be stiff – provides
maneuverability and lift
Fishes have two types of muscle – red and white – red muscle gets its color from the high concentration of myoglobin (stores oxygen)
Red muscle – best suited for long sustained effort – for sustained cruising
Fishes have two types of muscle – red and white – red muscle gets its color from the high concentration of myoglobin (stores oxygen)
Red muscle – best suited for long sustained effort – for sustained cruising
White muscle – provides short burst of power
Epipelagic sharks, tuna and billfishes have evolved a system to conserve the heat generated by their muscles and keep their internal temperatures above that of the surrounding water
White muscle – provides short burst of power
Epipelagic sharks, tuna and billfishes have evolved a system to conserve the heat generated by their muscles and keep their internal temperatures above that of the surrounding water
Vertical MigrationVertical Migration
Pelagic waters are dangerous but they also contain the most food
Some zooplankton spend only part of their time near the surface and then retreat to safer, deeper water
Usually live at least 200m or 650 ft down
Pelagic waters are dangerous but they also contain the most food
Some zooplankton spend only part of their time near the surface and then retreat to safer, deeper water
Usually live at least 200m or 650 ft down
Epipelagic Food Webs
Epipelagic Food Webs
Of great interest, especially because epipelagic fishes provide food and employment to millions
Of great interest, especially because epipelagic fishes provide food and employment to millions
Trophic Levels and Energy Flow
Trophic Levels and Energy Flow
Very complexEpipelagic contains vast
numbers of different speciesFeeding habits of most of
them are poorly knownMost of the animals eat a
variety of prey often from different trophic levels
Very complexEpipelagic contains vast
numbers of different speciesFeeding habits of most of
them are poorly knownMost of the animals eat a
variety of prey often from different trophic levels
Most epipelagic animals consume different prey at different times in their lives
The basic flow of energy in the epipelagic can be depicted as phytoplankton zooplankton Small nekton Large nekton top predators
Most epipelagic animals consume different prey at different times in their lives
The basic flow of energy in the epipelagic can be depicted as phytoplankton zooplankton Small nekton Large nekton top predators
Epipelagic food chains usually have many steps and are generally longer than in other ecosystems
Tropical usually have more levels than colder waters
Epipelagic food chains usually have many steps and are generally longer than in other ecosystems
Tropical usually have more levels than colder waters
Epipelagic is an exception to the 10% rule
Herbivores pass on 20% and the carnivores pass on more than 10% also
Epipelagic is an exception to the 10% rule
Herbivores pass on 20% and the carnivores pass on more than 10% also
Patterns of ProductionPatterns of Production
Epipelagic food webs are complex but they all share one simple feature: primary production by phytoplankton is the base
Epipelagic food webs are complex but they all share one simple feature: primary production by phytoplankton is the base
Some areas of the epipelagic are among the most productive on earth and some are “deserts”
Some areas of the epipelagic are among the most productive on earth and some are “deserts”
Phytoplankton need 2 main things to perform
photosynthesis:
Phytoplankton need 2 main things to perform
photosynthesis:
SunlightSupply of essential nutrients
SunlightSupply of essential nutrients
Red areas contain the most life, while the purple areas are nearly empty of life. Ocean areas of high productivity support more life than less productive areas. It is as simple as more food = more fish. More oxygen is produced and carbon dioxide consumed in these highly productive areas of the ocean.
Ocean ProductivityOcean Productivity
Light LimitationLight Limitation
Must get all their light during the day
May be light-limited during the winter
Total primary production also depends on how far down light penetrates into the water column
Must get all their light during the day
May be light-limited during the winter
Total primary production also depends on how far down light penetrates into the water column
NutrientsNutrients
Nitrogen, iron and phosphorus play a major part in controlling primary production
Nitrogen is most often the limiting nutrient
Most nutrients come from recycling
Nitrogen, iron and phosphorus play a major part in controlling primary production
Nitrogen is most often the limiting nutrient
Most nutrients come from recycling
Much of the organic matter ends up as detritus (fecal pellets, dead bodies)
Often the detritus sinks past the epipelagic zone before it releases its nutrients
Deep water is usually nutrient rich
Much of the organic matter ends up as detritus (fecal pellets, dead bodies)
Often the detritus sinks past the epipelagic zone before it releases its nutrients
Deep water is usually nutrient rich
Seasonal PatternsSeasonal Patterns
Can cause nutrient laden cold water to come to the surface
As the water cools it sinks, breaks up the thermocline and allows surface waters to mix with deep nutrient rich water
Can cause nutrient laden cold water to come to the surface
As the water cools it sinks, breaks up the thermocline and allows surface waters to mix with deep nutrient rich water
UpwellingUpwelling
Caused by Ekman TransportOccur mainly along the
eastern sides of ocean basins where the prevailing winds blow parallel to the coast
Ekman transport carries the warm surface water offshore
Caused by Ekman TransportOccur mainly along the
eastern sides of ocean basins where the prevailing winds blow parallel to the coast
Ekman transport carries the warm surface water offshore
This allows the deeper nutrient rich water to move to the surface
Major coastal upwelling areas are among the most productive waters of the epipelagic
In the pacific there can be equatorial upwelling
This allows the deeper nutrient rich water to move to the surface
Major coastal upwelling areas are among the most productive waters of the epipelagic
In the pacific there can be equatorial upwelling