Marine EcologySection 1: Energy Flow in the Ocean

1) Energy Flow in Ecosystemsa) Energy flows through an ecosystem in one direction.

i) This means energy enters an ecosystem in one form and never is converted back to that form again(1) I.E- Energy enters as light, that light energy is converted into chemical energy (sugar) through

photosynthesis and it is never converted back to light again ii) Food chains and food web show the flow of energy

(1) Trophic Levels – each step in a food chain/web(2) Ecological Pyramids – shows relative amount of energy at each level

(a) Because some energy is lost or used up every time it moves up a trophic level, the higher an

organism eats on the food chain/web the more that organism needs to eat in order to get a sufficient amount of energy

1) Interpretation of a food weba) Arrows point from prey to predatorb) Apex predator – the organism(s) that are not consumed by any other organism

c) Primary producer – the organism(s) that do not consume any organism (photo or chemo synthesizers)

Divide this Food web into all its trophic levels and label them

1) What is the primary Producer?

2) What is the apex predator?

3) Name some Primary consumers?

4) Name some secondary consumers?

5) What would happen to the Krill population if the adult herring population increased?

6) What would happen to the comb jelly population if the Barnacle larvae population increased?

7) What would happen to the water flea population if the adult herring population decreased?

2) How energy enters the marine ecosystema) Autotrophs /Primary Producers– Organisms

that convert energy from the sun or

chemicals into food i) In the marine ecosystem the most

productive autotrophs are algae like phytoplankton and seaweed (on land its plants)

ii) certain bacteria and plants play a smaller role in production in the ocean

3) The main Autotrophs/Primary producers in the oceana) Phytoplankton - small

photosynthetic organisms that

drift or floati) Includes many different types of

organisms such as bacteria, diatoms, and dinoflagellates.

ii) Perform more than 95% of the photosynthesis in the sea.

iii) Forms the basis of many

marine food chains.

iv) Phytoplankton is usually classified by

size

b) Seaweeds - multicellular photosynthetic algaei) Seaweed is usually classified by

colorii) Look similar to plants but do not have

true roots, stems and leaves and so they are not plants

(1) Blade = leaf

(2) Stipe = stem

(3) Hold fast = rootsiii) Pneumatocysts - air-filled sacs in the

seaweed that helps the blades float(1) This helps seaweed photosynthesize by causing the blades to float higher in the water

c) Marine Plants – plants that are adapted to be partially or completely submerged in sea water i) Sea Grass - the only true marine plant that can survive fully submerged in salt water for its

entire life cycle.ii) All other plants spend most of their live above water, only having their roots submerged in salt water.

(1) Cord Grass – a type of grass that grows along the coast in temperate areas.(a) Cord grass can only have its roots submerged for part of the day

(2) Mangrove forests – large trees and other plants that grow along the coast in tropical areas.(a) Mangroves are easily identified by

their roots witch stick up in the air and water to those parts of the plant get enough oxygen

4) Heterotrophs/Consumersa) Zooplankton – small organisms that drift or float but DON’T photosynthesize

i) Zooplankton usually consumes phytoplankton in the ocean and so it is called a primary consumer(1) Krill is an example of

zooplanktonii) As consumers move up in trophies level,

there body mass tends to increase even though the amount of energy they consume is less

iii) The largest organisms in the ocean eat lower on the food web

5) Organism Interactionsa) Symbiosis - any relationship where two species live closely together.

i) Mutualism - Both benefit(1) How do the clownfish and anemone benefit each other.

ii) Commensalism – one benefits, the other is not helped nor harmed(1) Ex: Remoras and Sharks: remora follows the sharks to eat the left over scraps.

iii) Parasitism – one benefits, other is harmed(1) Ex: An isopod sucking blood from a fish.

iv) Predation - One organism consumes another organism.(1) Why predation is not considered a symbiotic relationship?

(2) What is the difference between predation and parasitism?

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Why:_______________

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Section 2: Populations

6) Population Growtha) A population of organisms can grow 2 ways:

i)Exponentially ii) logistically

b) Under ideal conditions a population will grow exponentially

i) Exponential Growth- individuals reproduce at a constant rate.(1) The larger the population the faster it grows.

(a) Ex: 1 cell of phytoplankton reproduces every 20 minutes, how many dinoflagellates would there be after one day? ANSW: More than a billon cells

c) When the availability of resources is limited or insufficienti) Logistic Growth- when population growth slows or stops

d) There are a number of factors that go into limiting population growthi) Carrying Capacity - The largest number of individuals that an environment can support because of the

limitation of resources

(1) Limiting Resource- a resource in short supply and restricts population growth(a) Light and nutrients act as the limiting resources for primary production in different parts of the

ocean (i) Polar waters – the regions of the ocean farthest away from the equator that experience a single

bloom of phytoplankton during the summer due to the limitation of light1. Although the water in polar regions is packed with nutrients, the availability of light is

limited to half the year(ii) Tropical waters – the regions of

the ocean closest to the equator experience a consistent level of population of phytoplankton due to the limitation of nutrients1. Although the water in tropical

regions stays lit for long periods of the day, the availability of nutrients is limited due to the large population of organisms

(iii) Temperate waters – the regions of the ocean between polar and tropical waters experience two pulses of phytoplankton in the spring and fall due to the limitation of both light and nutrients1. During the winter in

temperate waters, there is not enough light to support photosynthesis.

2. Once light becomes available populations of plankton start to grow exponentially and so nutrients quickly become limited

7) Population Declinea) If we remove too many organisms from the ocean

the population will not be able to recover.b) Maximum Sustainable Yield- the highest number of

a species that can be removed without

depleting a population over time.

c) Overfishing- fishing beyond the maximum

sustainable yield, i) Overfishing causes fish populations to dwindle

or disappear over timeii) As the worlds fishing effort increased over the

past 50 years the amount of fish caught year to year has begun to decreases.

iii) It is currently estimated that 70% of the world’s fisheries are overfished

1960 1970 1980 1990 2000 20100%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Marine Fish Stocks Over Time

Crashedoverfishedfished to maximum sustanable yieldfished under maxmum sus-tanable yield

Section 4: Nutrient Cycles

8) Nutrients are constantly cycling in the environment.a) Nutrients come from the atmosphere or from weathering rock.

b) Nutrients are used by organisms to build molecules (proteins, carbohydrates, DNA and fat) that are essential to life.

c) When organism eventually die, some parts of the organism dissolve in water while other parts do not.i) Detrius - particles of nonliving organic material (bodies of dead fish, animal poop)

ii) DOM - dissolved organic material (waters and parts of the dead animal that dissolve in water)

d) The three nutrients that cycle are Phosphorous (P), Carbon (C), and Nitrogen (N)

9) Phosphorous Cycle a) There is no phosphorous gas.

i) Phosphate is add to through weathering rock and fertilizer runoff.

ii) Phosphate is taken up by autotrophs which are eaten by animals.

iii) Once any organism dies phosphorous is re dissolved in the ocean through decomposing bacteria or becomes fossilized in sedimen

10) Carbon Cycle a) Carbon moves back and forth between the

ocean and the atmosphere as CO2.i) Dissolved carbon is absorbed by

autotrophs and used in photosynthesisii) After being converted to sugar through

photosynthesis, it is converted back to CO2

through respirationiii) CO2 can also be absorbed by a number of

organisms that can convert CO2 to CaCO3

(limestone) which they use to make shells or exoskeletons

11) Nitrogen Cycle a) Most nitrogen exist as nitrogen gas (N2) which

most living things cannot use.i) Nitrogen gas is converted to useable

forms of nitrogen through Nitrogen fixing bacteria(1) Nitrogen fixing bacteria - the only

organism that can take nirtogen gas (N2) and convert it into ammonia (NH3), nitrite (NO2) and eventually nitrate (NO3).

(2) Nitrate is the only compound that is not toxic and can be used by plants and animals.

(3) Denitrifying Bacteria - Converts nitrates (NO3), nitrite (NO2) and ammonia (NH3) back into nitrogen gas

Section 5: Humans and the Ocean

12) Biodiversity is the total variety of organisms living in an area.a) There are many human caused threats to biodiversity

i)Overfishing/Hunting ii) Pollution iii)Habitat Loss

13) Overfishing = Hunting to Extinction a) Extinction - the disappearance of

organisms who cannot adapt to changes in the environment.i) Extinction is a natural process, but

humans have cause many organisms to become extinct or nearly extinct.

ii) Not all extinction is caused by direct hunting or fishing(1) Incidental Catches - when you

catch one organism while you are

fishing for a different organism.

(2) Ex: Dolphins were often caught and killed in tuna nets. Dolphin Safe Tuna uses methods that don’t harm dolphins.

b) Fishing Down Food Webs: i) Most of the large, top predators

have been removed from the ocean to such a degree that it is no longer economically beneficial to fish them(1) When this happens humans

then begin to focus on fishing for smaller and smaller fish.

(2) When you fish down

the food web entire ocean food chains can be destroyed.

14) Solutions to Overfishing/Hunting a) Mariculture - Raising marine organisms for food.

i) Decreases the rate of overfishing of larger fish.ii) Problems with Mariculture:

(1) Need to catch lost of smaller fish to feed to larger fish.(a) Ex: 3 lb’s of smaller fish go into every pound of farm raised samon

(2) Not all organisms can be raised on a farm economically.(a) 3 Criteria for Organisms in Mariculture

(i) Matures fast (ii) Sells for enough money (iii) Easy and inexpensive to grow

b) Quota System- the governments of many nations now regulate the amount of cirtan fish that can be caught by finning those fishermen that catch over there allowancei) This causes a lot of money to regulate appropriately

ii) Fishermen end up making less money or go unemployediii) This puts more pressure on non-quota fishiv) The maximum catch regulated by the quota is hard to estimate accurately and thus many fish

may still be overfished even though the quota is being obayed

15) Pollution a) Oil

i) Oil gets into the ocean several ways.(1) Natural seeps (not pollution)

(2) Surface runoff (3) Transportation and Extraction of Oil

ii) The effects of Oil(1) Inhibits the growth of phytoplankton(2) Fish are more susceptible to disease(3) Coats the feathers of sea birds causing them to die from being to cold.

iii) Oil is decomposed by bacteria (100% biodegradable) but the process is slow (1 – 30 years)

Natural Oil Seeps47%

Runoff as well as Individual Boats & Cars

38%

Oil Spills & Industral Accedents

15%

Sources of Oil in the Ocean

b) Garbagei) The great pacific garbage patch – a patch marine litter (plastic and chemical sludge) twice

the size of texas rotating in the north pacific ocean

(1) It collects there because of current called the north pacific gyre

(2) Mostly from garbage washing into the ocean from land/landfills(3) Not visible from satellite pictures because the plastic floats just under the

surface of the water

16) Habitat Loss a) About one third of all of temperate salt marshes and tropical mangrove forest have been destroyed.b) The habitats that are destroyed are the most productive habitats in the world.

i) Supports the most life and removes the most amount of CO2 from the airii) Reasons for Habitat Loss

(1) Cleared for mariculture

(2) Used for garbage dumps(3) Cleared for to make factories or marinas.

iii) Importance of salt marshes and mangrove forests.(1) Natural water purification system

(2) Nurseries for fish

(3) Very high primary productivity(4) Habitat for many organisms

iv) 25 % of the coral reefs have been destroyed.(1) Coral are collected and sold as souvenirs.(2) Human activity stirs up sediments in the water which blocks sunlight.