Transcript Deep Sea - TeacherWeb

Aphotic Ecosystems
A World Without Light
Plate Tectonics
Convergence
Continental Mountain Ranges
Subduction Zones: Trenches
Volcanic Mountain Ranges or Island Arcs form on the continental plate
Seafloor is made of dense basalt which “dives” under lighter continental granite
Aleutian Islands
Island Arcs - when
ocean plate collides
with ocean plate
Location of Plates
Hot Spots



Hot spots remain stationary, but above them, the
Earth's crustal plates move slowly.
Imagine moving a sheet of paper horizontally a
few inches above a burning candle.
Similar to the candle's flame, a hot spot leaves a
scorched trail of volcanic islands on its overlying
plate.
Zones review

What are the open ocean
zones?





Epipelagic
Mesopelagic
Bathypelagic
Abyssoplegic
Hadalpelagic


Which are photic?



Every Mother Buys A
Handbag
Only the epipelagic (top
100m) lies in the photic
zone
Photosynthesis
Which are aphotic?


All the rest
No photosynthesis
Oxygen in the Deep Sea


Depend on the surface for
Oxygen
Oxygen Balance



Added
 Mixing
 Photosynthesis
Taken out
 Respiration
Thermohaline Circulation

Ocean Conveyor Belt

Brings oxygen to deep sea
The map shows how oxygen is
distributed in the global ocean.
Regions of near-zero oxygen, are
colored purple and are
concentrated in the tropics.
Ocean Conveyor Belt provides Oxygen to
the Deep Sea as Cold Dense Water Sinks
http://www.divediscover.whoi.edu/circulation/index.html
Epipelagic



Photosynthesis
Lots of oxygen & food
Fish

Fast swimming



Streamlined
Strong muscles
Countershading



Dark dorsal side
Light ventral side
Helps organisms hide
Mesopelagic




Twilight Zone
Some light but not
enough for
photosynthesis
200m-1000m
Main thermocline occurs
here



Rapid temperature change
Density layer (invisible
barrier)
Organisms that move
through this layer must be
adapted to deal with this
temperature change
Zooplankton of the Mesopelagic:
Midwater Organisms


Krill, shrimp & copepods
Ostracods





Amphipods
Arrow worms




Carapace that makes them
look like clams with legs
Usually 1/8 in long
Gigantocypris is ½ in
Worm-like predators
Squid
Jellies & comb jellies
Photophores

Bioluminescent organs
Fish of the Mesopelagic:
Midwater Organisms




Most fish are very
small
Hatchetfish
Viperfish
Bristlemouths are
most common


Cyclothone
signata is the
most abundant
fish on earth
Photophores
Adaptations in Mesopelagic:
Feeding

Gulper Eel Loosely
hinged,
huge mouth
Lack of food






Small size (growing takes
energy)
Live under productive
oceans where there is
more detritus
Large mouths to avoid
gape limitation
Elastic stomach to eat
organisms larger than
themselves
Broad diets (eat anything
they can find)
Some move to the surface
at night to feed
Adaptations in Mesopelagic:
Vertical Migration

Migratory (up to feed at night & down to hide
during day)

Layer of vertical migrators is called the Deep
Scattering Layer



Tolerate wide range of temperatures as they cross the thermocline
Strong muscles & bones
Swim bladder (helps keep buoyancy when changing depth)
 Can rapidly release gas
 Many filled with fat instead
Adaptations in Mesopelagic:
Vertical Migration

Non-migratory





Eat detritus-decaying organic matter from the
epipelagic
Flabby muscles/weak bones makes them more
buoyant
Don’t swim much so they aren’t very streamlined
No swim bladder (saves energy)
Eat the vertical migrating fish because they are more
nutritious than non-migrators
Adaptations in Mesopelagic:
Sense Organs

Large sensitive eyes

Some have tubular eyes



Like having 2 pairs of eyes
See well only in the direction
they are aimed (usually
upward)
Have a second retina to
compensate & aid in lateral
vision


Retinas are the light sensitive
part of the eye located on the
back
Second retina is on the side
to aid seeing objects on the
side
Adaptations in Mesopelagic:
Coloration & Body Shape

Takes too much energy to swim fast or grow spines for
predator avoidance

Camouflage is main source of protection




Transparency
 More common in shallower mesopelagic
Silvery
 Middle of mesopelagic
Red or Black
 Deeper mesopelagic
 Red light is the first light filtered out so red appears black in the depths
 Black is a bit more visible because blue light is reflected
Countershading


Black back & silvery sides
Reduction of silhouette

long thin bodies that disappear from some angles
Adaptations of Mesoplegaic:
Bioluminescence


Attract mates or Communication
Confuse Predators



Bioluminescent fluids
 Squirt these fluids out to distract predators
Counterillumination (like countershading)
 Photophores on the belly match blue-green sunlight above
 Symbiotic bacteria or chemical in tissues
 Can control intensity (brightness) of their photophores
 Animals looking up at their prey can’t see the shadow that would be produced
 Tests on bioluminescent shrimp show that this is controlled by eyesight
 Shrimp with blinders produce no light
 Eyes exposed to more light/ shrimps bodies produced brighter
bioluminescence
Attract or see prey



Bioluminescent anglerfish lures
Or headlights used like flashlights (some are even red lights to see red fish)
Some predatory fish have special eyes that can tell the difference between
photophores and the sun!
Adaptations of Mesopelagic:
Oxygen Minimum Layer

500m Oxygen Minimum



Not in contact with atmosphere
Little or no photosynthesis
Lots of respiration




more detritus than deeper zones
Large gills
Inactive so they use less
oxygen
Hemoglobin



Protein in blood
Transports oxygen to body
tissues
Functions well in low oxygen
environments
Deep Sea Pelagic





Largest environment on
earth
75% of the ocean
Area of the ocean that
receives no light
No seafloor bottom
Relatively constant physical
environment


Little change in temp (2C),
light (none), salinity etc.
Includes:



Bathypelagic
Abyssopelagic
Hadopelagic (trenches)
Deep Sea Pelagic:
Bioluminescence, camouflage & vision

Bioluminescence





Courtship,
communication, attracting
prey, confusing predators
Not for counter
illumination
Less common than in
mesopelagic
Most organisms are
black or red
Small eyes or blindness
Deep Sea Pelagic:
Lack of food




Only 5% of photic production
makes it as detritus 20% in
mesopelagic
Large mouths & stomachs
No vertical migration
Hardly move / wait for prey


Lure prey
Small, but larger than
mesopelagic







Grow slowly but live longer than
in mesopelagic
Reproduce later in life
Flabby muscles & weak bones
Poorly developed circulatory &
nervous systems
No scales
No swim bladders
Can use energy that isn’t used
in migration & reproduction
Deep Sea Pelagic:
Reproduction
Mates are hide to find






Hermaphrodites




Can mate with anyone in the
species
Both are fertilized
2 for the price of one
Attract mates



Right species
Right gender
Low abundance
High diversity
Pheromones-chemicals in the
water
bioluminescence
Male parasitism

Males permanently attach to
females
Deep Sea Pelagic:
Extreme Pressure



Makes it hard to study the
deep
Pressure resistant
enzymes
Lack swim bladders


Deepest fish


Too much energy to fill in
the deep
8,370 m
Invertebrates


Found in Mariana Trench
11,022m
Deep Sea Pelagic Fish






Small, but larger than
mesopelagic
No streamlining
Weak flabby muscles
Small eyes / no eyes
Black, red, or no color
Bioluminescence

Attract mates & prey
Benthic Deep Sea:
Food

Deep seafloor & detritus

Detritus from above sinks to the
bottom





Food that is missed doesn't keep
sinking
Food particles accumulate on benthos
Bacteria



Marine snow
Most is eaten before it reaches the
bottom
Decompose detritus
Bacteria are eaten
Deposit feeders



Eat food that has settled on the bottom
Infauna-live in sediment
Epifauna-live on sediment

(all pictured)
Benthic Deep Sea Fish






Large
Elongated bodies
Strong muscles
Small eyes
Dark brown, white or
black
Only some
bioluminescense
Location of Seeps & Vents
Bacteria & Bologna



Alvin sank with lunches on board
sub was recovered after ten months on the
bottom
the seawater soaked lunches were in a
remarkable state of preservation.




Bologna sandwiches were not spoiled and the meat
was still pink.
The apples tasted salty, but were still quite fresh.
The lunches had just been sitting in an open leather
satchel inside the sub, protected from all the little
scavenging animals, but free for microbes to act.
Decomposition is slow & so is metabolism
Oasis: Cold Seeps

Discovered 1984 in Gulf of
Mexico

Methane & sulfur seep out
of the ground




Methane hydrate is frozen, but
not cold to the touch and will
light on fire if you put a match
to it “fire ice”
Slow & steady emisson
Chemosynthesizing bacteria
Slow growth rates

World oldest invertebrate


Lamellibrachia luymesi
Live 250 years
Oasis: Brine Pool

extreme concentration of salinity





rich sources of methane


5x the salinity of the ocean
Kills organisms accidentally
swimming into them
So salty that the submersibles (like
Alvin) can hardly penetrate into
them
just sit there, on top of the salt"inversion" boundary.
Chemosynthesis
dense colonies of mussels form
on the halocline


symbiotic relationship with
methanogenic (methanemetabolizing) bacteria
Bacteria live in the gills
Oasis: Whale falls



Discovered in 1987
Whale or other animal
carcass that has
fallen to the seafloor
Feeds scavengers for
decades

Water seeps into seafloor
fissures
Oasis:
Hydrothermal Vents


Water jets out of vents in the
seafloor




hits cold water,
minerals precipitate out &
leave mineral deposits that build
up into chimneys or smokers
(white or black)
H2S (hydrogen sulfide) is also
released,


heats up, reemerges loaded with
minerals
used by chemosynthetic bacteria
Biology:



High abundance
Low diversity
Tubeworms

Riftia - 6 - 10 feet long, Alvinella,
Tevnia, Pompeii worm
Discovery of Vents

Found in 1977 in the
Galapagos Rift valley

Marine Geologists

Scientists thought that
there was no life in the
depths (no life without
light)

Alvin submersible
Location of vents
Vents are found on Ridges
Phylum: Annelida