12(1)
LIFE; ENERGY; PHOTOSYNTHESIS;
FOODWEBS
I. LIFE
Main intent of Ch. 12 -- Inter-relationship between life and
energy
,Basic life processes w.r.t. flow of enrgy
.How ocean impedes or facilitates energy flow
A. Tough to define "life" ....
,Both simple and complex
.Simple-just a few atoms (C,H,O,etc)
,Complex - lots of combinations
.Some atoms found in both living and non-living things
.Some energy too
Try defining life in terms of interaction w/ energy
LIFE REQUIRES ENERGY
ALL life is involved in energy transformation
Examples:
.Plants transform light energy into chemical energy
,Animals transfer chemical energy to kinetic energy or heat
energy
-Main source of energy for living things on Earth is... Look it up
-Energy transformed from sunlight to Chem energy to heat energy
-As sun dies, so will life on Earth
12(2)
B. Working definition of "life"
'organisms can capture, store, and transmit energy"
'organisms can reproduce, change through time, and adapt to
their environment"
-Essen. diffs between living and non living systems:
 .The way living things use energy
 Extent to which molecules are organized
II ENERGY
A. Capture and flow of energy -Basic unit of life is the cell
-Virtually all organisms are composed of one or more cells
-Flow of energy occurs both within and between cells
-Nearly all energy used by cells comes directly or indirectly from
sun
 Energy flow
-Light trapped by chlorophyll in producers (bacteria,
algae, green plants), changed into chemical energy
-Chem energy used to build food (carbonhydrates and
organic molecules)
-Food then used by plant or eaten by animals
-Energy then released when food is used for growth,
repair, movement, etc.
-Metabolism of food produces waste heat which flows into
space.
 Energy capture and photosynthesis
Ist step in conversion -light energy to chemical energy -start
with a plant -chlorophyll molecule critical in process;
chlorophyll collects energy from light photons, transfers energy
to electrons.
-Energy carried by electrons through series of biochemical
rxns.
12(3)
•Some energy used making ATP
(adenosine triphosphate)
 Most energy used to make glucose, a
carbohydrate and small food molecule
*Glucose used to produce more ATP, which allows plant to grow,
reproduce, synthesize chemicals. This process of using light
energy to synthsize molecules is photosynthesis
General formula for photosynthsis:
6 C02 + 6 H20 + energy
C6H1206 + 6 02
carbon dioxide + water + (sunlight)
glucose + oxygen
 Photosynthesis produces organic matter from
inorganic matter. This process known as Primary
productivity,
•Energy harvest
Plants make food through photosynthesis, can meet their own
needs
-Animals cannot make their own food so they must consume
plants or other animals that have consumed plants (or other
animals that have consumed plants)
All life needs ATP
Food that is consumed needs to be dissassembled in order for
glucose enrgy to be "harvested" by conversion to ATP
This process is known as "respiration" (like breathing)
It's reverse of photosynthetic rxn:
C6 H12 06 + 602
6C02 +6H20 + energy to make ATP
12(4)
Thus, light energy that powered the rxn the first time becomes
chemical energy holding together ATP.
III.
Feeding relationships
A. Nourishment - 2 ways to get it
I. Autotroph ; self - nourishment ; "primary producers"
2. Heterotroph - can't self-nourish
Thus, heterotrophs consume autotrophs (and other
heterotrophs)
Hierarchy of producers and consumers
Even in consumption process, much energy is lost: only 10% of
energy consumed gets stored in flesh of a consumer
As result, have a trophic pyramid, where relationships
change by a factor of 10 at each level
For example , to get I kg of tuna, 10,000 kg of
phytoplankton must be consumed
•Rather than food chains, look at feeding relationships as food
webs.
12(5)
I. PHYSICAL FACTORS
Definition-"any aspect of phys. environment that affects living
organisms is a physical factor"
Factors are:
A. Water transparency
E. Dissolved gases
B. Dissolved nutrients
F. Acid-base balance
G. Temperature
G. Hydrostatic pressure
D. Salinity
A. Water transparency
-most photosynthesis occurs above depth of 40 m
(130') in the ephotic ("good light") zone (which is the
upper 1/2 of the photic zone)
-Nearly all marine life depends on this thin zone
B. Dissolved nutrients
-Autotrophs require nutrients to produce organic
matter
• Nutrient is a substance that an organism obtains from its
environment (excluding 02, C02, H20)
•Main inorganic nutrients required for primary
productivity are:
-Nitrogen (in nitrate, N03 )
-Phosphorus (in phosphate, P04)
C. Temperature
-Reaction rates are sensitive to temperature
-Metabolic rate increases 50% w/ 10° C (1B ° F)nincrease
in T
•Most organisms are ectothermic ("outside heat") and
cold-blooded
*Few organisms are endothermic, ("within heat") and
warm blooded
12(6)
• In general, the warmer an ectotherm, the higher its
metabolic rate.
Tropical fish exampleIn heated aquarium, they eat more
food, grow faster, have faster heartbeat, swim faster
 Endotherms have internally controlled metabolic rates which
operate in narrow range.
 Marine water acts as a moderating influence on biochemical
reations, (can accept changes in heat w/out changing temp
much)
D. Salinity -Can greatly affect cell membranes -Relatively
easy for most species to maintain salt balance
E. Dissolved Gases
-C02 very soluble in water
-C02 plentiful for marine plants
-Oxygen can sometimes be low near surface - O2 made
during day may be consumed at night
extreme cases of 02 starvation are assoc. with plankton"blooms"
and cause death of plants and animals (all O2 respired by
plankton)
F. pH (acid-base balance) -Normal range narrow -when primary
produc high, pH may rise slightly (less acidic) because C02 is
being used in photosynthesis -coral roof example: cool water
and high C02 solubility keep making carbonic acid, which in
turn keeps C&C03 from precipitating.
12(7)
G. Hydrostatic Pressure
-orgs are subjected to great external pressure
-but internal pressure is high also, so the two balance
out
-thus, marine orgs don't need heavy shells to keep from
being crushed
H. Interplay of phyuslcal factors -charge in one affects others example:
springtime in the ocean
Temp up; evap up; salinity up; density up; warm dense water sinks; cool
nutrient rich water rises; plants are stimulated; C02 absorbed in
plants; pH of ocean rises
"limiting factor"-when too much or too little of a single factor adversely
affects organism
eg: not enough light or too much heat
II BIOLOGICAL FACTORS
-Definition- "biologically generated aspect of environment
that affects living organisms."
Factors are:
A. Feeding (most impor)
C. Metabolic wastes
B. Crowding
D. Territorial defense
Now look at biological action on the physical state (add'[ influences on
organisms)
A. Diffusion, osmosis, active transport.
o Diffusion - important process especially within and between cells,
over short distanc (Mass transport important over long distances)
12(8)
o Diffusion driven by concentration- substances move
from high to low concentration
o Diffusion often occurs across cell membranes example: 02
diffuses from inside a photosynthesizer to the outside
B. Specific type of diffusion - water- know as "osmosis"
o Water also moves from high to low concentrations (in this
case, low concentration of water may be a high
concentration of dissolved solids (high salinity)
example; fresher water outside a saline cell will diffuse into
the cell, moving from high (fresh) H2O concentration to lower
H2O conc.
-Most orgs have same concen of dissolved substances in they
are "isotonic" (equal-strength") so little to no net flow of H20
occurs across membranes
-"Hypertonic" ("over - strength"): animal experiences
water influx (animal fluids more saline than outside)
-"Hypotonic" under strength"): animal has water outflow
(animal fluids less saline than outside)
Some adaptive mechanisms:
-Many fish drink seawater to counteract dehydration
-Seabirds do same
-Salmon have large kidneys
Active transport
-reverse of passive diffusion
°Process is one of movement of dissolved substances from low
concentration to high concentration -process requires energy.
12(9)
Example- cell exports a "finished product" through a
membrane to a storage area with high concentration
of finished product
Final rate- diffusion, osmosis, active transport are all
temperature dependent
D. Surface/Volume ratio
-the smaller the cell, the more efficiently materials can cross
membrane -need a large surf/volume ratio, which you only get w/
a small cell
-If cell too large, inward and outward flow isn't high enough to
service the call.
E- Metabolic Rate and Dissolved Gases
-"interesting dilemma"
-less 02 available as metabolic rate increases, which is not good
for animals
F. Gravity and Buoyancy -density of seawater = density of
living material
Example: fish = 1.07 g/cc (bit heavier than water) have gas
filled bladders to increase buoyancy
Other examples
-few animals use NH4CI solution instead of seawater
-jelly fish actively transport out heavy ions, allowing
lighter
ions in. WHAT ARE THESE?
12(10)
G. Viscosity and movement
Definition:
viscosity is fluid's internal resistance to flow
-cold water more viscous by 25% than warm water
-salt water more viscous than fresh
c floating animals increase their drag and stay buoyant
with various appendages
o note that warm water species have more appendages
because warm water has less viscosity , making it easier
to sink
-Large swimmer minimize turbulence by adopting a teardrop
shape
H. Water movement
-ocean currents and water masses carry organisms
12(11)
Environment, classification, evolution
-I. Marine environment classification
-divide marine environment into zones.
zones have similar biological and physical factors
3 classification schemes
A. Light classification
1. Photic zone to depth of 200 min tropics- 100m in mid-lots
a. Euphotic ("good light") zone in upper 1/2 of photic
2. Aphotic zone ("without light")
B.
.
Temperature classification
I. Eurythermal-above thermocline
2. Disthermal - below thermocline
C. Location classification
-current scheme developed in 1950's
-useful because it can describe, generally,
I. Position from shore
2 Depth
Nonetheless, a bit confusing slightly inconsis. w/ Chap 5...
Break into 2 parts:
1. Actual water column "Pelagic" (of the sea) zone
2. Actual sea floor "Benthic" (of the bottom)
• Both water column and sea floor subdivided
1. Water column:
a "Neritic" zone-(continental shelf)
b. "Oceanic"(cont slope, rise, abyssal plain
2. Sea bottom similarly subdivided
Pelagic zone
Water column
Depth (m)
Neritic zone
High-low tide
i Epipelagic (top)
0-200
ii Mesopelagic ('Middle") 200-7000
iii. Bathypelagic ("deep") 1000-2000
iv. Abyssalpelagic ("w/out bottom") 2000-6000
(v. Hadal pelagic ("under world") 6000-bottom
(after Hades ....)
12(12)
Benthic zone
Sea bottom
Littoral
Sublittoral
Bathyal
Bathyal
Abyssal
Hadal
II EVOLUTION AND LIFE IN OCEAN
='Life on Earth seems well-suited to physical conds"
-It is not by accident. It is by adaptation to the physical
and chemical environment.
This adaptation over time is known as evolution
"Evolution" means change.
A. Culture in 19th century embraced Bishop Usshers 6,000 yr-old age
estimate for Earth.
-Charles Darwin was studying at Cambridge, saw road cuts exposing
rx that Charles Lyell (geologist) had studied.
o Lyell suggested that mtn-building and erosive processes are very slow,
which in turn suggest Earth is old
o Some "radicals" thought Earth could be very old
-Darwin had opportunity to be a staff naturalist on HMS Beagle The
5 year voyage caused him to observe the "species problem":
(12-13)
•If breeders were able to change plants and animals quite
quickly, could species change by themselves given
enough time?
-Darwin amassed data for 20 years, but didn't publish until 1858.
"on the origin of species by natural selection"
B. Main points of theory of natural selection
• Random variations (mutations) in species occur as
inheritable traits
*Some mutations are favorable and increase ability to survive
*Increased survival leads to increased roproduction, and mutations
become more widespread as genes become widespread
Example: Tuna born with no eyes can't see to feed, will die before it
can reproduce
Tuna with great eyesight will eat a lot, reproduce a lot, spread its genes
a lot, spawning lots of little tunas w/ great eyesight
-Evolution by natural selection is a series of favorable
adaptations to environment by successive generations of a
species
o If organism is successful, it will survive and breed, spawning later
generations with its characteristics
o If unsuccessful, organism will die out, and not breed, so its
unfavorable adaptations will not be passed down to other
generations.
(12-14)
-Definiton of species
-group of interbreeding organisms that is reproductively
isolated from all other life
Example-all domestic dogs are members of one species
-Process of species formation known as "speciation"
o can happen quickly in a small population (like Galapogos
Islands where Darwin studied)
o Galapagos birds and lizards not same species as South
American counterparts--they evolved differently because
of isolation
o Australia and marsupials (like kangaroo), another
example-placental animals became dominant in other part
of the world, but marsupials stayed dominant in Australia
and divergently evolved into may diff species without the
competiton from placental animals
C. Evolution in the marine environment
-Similar physical conditions in ocean (ie water) lead to
similar shapes of different animals • Shark-fish
o penguin-bird
o porpoise-mammal
-Physics of moving through water have caused "selection" of this shape
by nature.
• Process is convergent evolution
In summary, the "organisms are right for the environment" because they
adapt through evolution.