Chapter 7: Introduction to Life in the Sea

Question 1

When did photosynthesis occur and what is this phenomenon called and how did it impact our current world? and what did that mean for organisms?

Answer 1

Occurred about 2.4 billion years ago and it supported organisms (this was called the great oxidation, and now 21% of our atmosphere is O2) that were aerobic (organisms that require oxygen)

Question 2

How is the majority of the sea supported? Carbohydrates?

Answer 2

It is supported by photosynthetic organisms that absorb the sun’s energy, convert it to chemical energy, and then use that chemical energy to make organic material: carbohydrates, or ‘food’.

The carbohydrates are a form of stored chemical energy for use by the photosynthesis organisms as well as for other organisms that feed on them.

Question 3

What else helps support the production of food in the sea?

Answer 3

Food production in the ocean is not limited to photosynthesis; some is produced by bacteria using chemical energy to synthesize organic material, not light energy; this process is called Chemosynthesis.

Question 4

What do we call organisms that make their own food through photosynthesis or chemosynthesis? Where are they in line on the food web?

Answer 4

Autotrophs, meaning that they make their own food

They are primary producers (in other words, they produce the base of the marine food chain)

Question 5

heterotrophs?

Answer 5

organisms that cannot produce their own food, so they have to eat

Question 6

At what rate do primary producers produce food?

Biomass vs. primary production?

Answer 6

They produce at a rate that is called primary production

Biomass: the measure of how much food there is at any one time (it is also the static measure of how much)
Primary production: a dynamic measure of how much is made per unit time (e.g how many grams per day)

Question 7

What is most of the photosynthetic primary production in the sea performed by? micro-algae vs macro-algae?

Answer 7

Phytoplankton: they’re a diverse group of single-celled organisms that include micro-algae, the single-celled algae (nonvascular plants), and many more other taxa

macro-algae: the larger forms that include the kelp and seaweed, they’re near the shallow water near the shore

macro-algae not as important as phytoplankton (single-celled phytoplankton which are responsible for the vast majority of the ocean’s primary production)

Question 8

Size of phytoplankton?

Answer 8

so small, measured in micrometers or microns (um)
1 micrometer, or 1 micron
= 10^-6 meters (1 million of a meter)
= 10^-3 millimeter ( 1 thousandth of a millimeter)

Question 9

What does phytoplankton need to photosynthesize?

Answer 9

Everything they need to photosynthesize and grow is dissolved in the water that surrounds them and is transported into their cells across a cell membrane, while wastes are transported in the other direction.

Question 10

Photosynthesis? Photosynthetic pigments (types?) ?

Answer 10

Photosynthesis: the process where organisms use hte Sun’s energy to synthesize organic matter (simple sugars) from inorganic matter (carbon dioxide) - use photosynthetic pigment to capture the sun’s energy and convert it into chemical energy, which is stored inside their cells in the form of a high-energy molecule (glucose).

chlorophyll: most common in both the macroalgae and phytoplankton (a type of photosynthetic pigment) - most microalgae and macroalgae have accessory pigments (in addition to chlorophyll)

Question 11

Photosynthetic pigments have done what to algae?

Answer 11

They have helped classify their pigment; so, the chlorophyll molecule absorbs primarily blue light (as well as some red light) and reflects green light; not coincidentally, blue light attenuates quickly with depth, such that photosynthesis is possible only at relatively shallow depth, with the majority confined at the top 100 meters (m) or so of the ocean.

Question 12

Photosynthesis chemical structure?

Answer 12

C02 + H20 + Energy –> CH2O + O2
photosynthesis

inorganic matter (CO2) and water are dissolved in the sea and their is energy input and it forms carbohydrates (or glucose) and oxygen
so energy, inorganic carbon and water is inserted, then carbohydrates and oxygen is released

Question 13

Respiration Equation? What does it provide? What is biosynthesis?

Answer 13

CH2O +O2 –> CO2 +H20 + Energy (heat)
carbohydrates are oxidized, making carbon dioxide and water and releasing energy

This equation provides the cell with chemical energy for metabolism, especially growth, which includes biosynthesis

Biosynthesis: utilizes the chemical energy to drive cellular reactions to form new body tissues

Question 14

Biosynthesis?

Answer 14

Some chemical energy released in respiration is stored in the form of high-energy chemical bonds in the molecule ATP, adenosine triphosphate, to generate this the cell needs more than just the basic (oxygen, carbon, and hydrogen); it needs phosphate (PO4^3- )
this is dissolved in water usually and transported across the cell membrane into the phytoplankton cell and the attachment of the third atom of phosphorous to the molecule adenosine diphosphate (ADP) makes ATP, then when one phosphorus atom is separated from ATP ( the stored chemical energy is released and THEN biosynthesis can be done); growth can be created but it needs more than just phosphorus, it needs nutrients

Question 15

acid-base reactions?

Answer 15

Acid: a chemical compound that is a proton donor; that is, it donates one or more hydrogen ions (H+; this is a proton), to another substance
Example: hydrochloric acid (HCI), and sulfuric acid –> these are acid based

Question 16

Chemicals needed for life? What else is necessary for life that is not abundant in the waters and what are they usually referred to as?

Answer 16

Carbon, Hydrogen, and Oxygen

Nutrients such as phosphate are not abundant in the waters, and they’re usually referred to as limiting nutrients

Question 17

What are the two groups that nutrients are categorized in? Examples? And what is a limiting factor?

Answer 17

Nutrients are categorized into two groups based on their percentage and composition in phytoplankton and other algae.
1) macronutrients: (nitrogen and phosphorous and sometimes silicon)
2) micronutrients: (S, Na, Cl, B, Mn, Mg, Zn, Si, Co, I, F, Fe, Cu, and others)
Both of them set a limit to biological production in the ocean, and sometimes, they run out and thus constitute to limiting factor (this means that cells are unable to grow since they can not obtain the nutrients needed, so they will cease growing etc., due to a limiting factor)

There are some parts in the ocean that can lack some certain times of the year and not allow for plankton to grow (sometimes nutrients are absent or in such low concentrations that phytoplankton cells are incapable of absorbing them out of the seawater and set up the upper limit to the amount of biomass that can be produce from phytoplankton)

Question 18

In addition to nutrients? what are other factors that can limit biological production?

Answer 18

1) Light intensity: near-freezing or very high temperatures in shallow, tropical lagoons (light or nutrients, rarely at once, that limit biological production in the sea)
2) temperature:

Question 19

Two most important quantities required for photosynthesis and growth of phytoplankton?

Answer 19

1) ligths and nutrients –> but they’re not in abundance everywhere in the oceans

Question 20

Where is light abundant and nutrients abundant in the ocean? and what does this mean in regards to phytoplankton?

Answer 20

Lights are abundant at the surface of the water, while nutrients are abundant at the bottom of the ocean
It is for this reason that nutrients are said to limit phytoplankton production in stratified waters

Question 21

Why is their more nutrients at the bottom of the ocean?

Answer 21

related to the uptake of dissolved nutrients by phytoplankton cells in the surface waters, and the “raining” down of that particulate biomass, in the form of dead cells, to deeper depths

Question 22

Two most important macronutrient elements that can become limiting for marine life (especially phytoplankton) are?

Answer 22

Nitrogen (N), Phosphorous (P) - both present in the ocean, but come from different sources; required by all phytoplankton and algae of the sea

Question 23

Phosphorus cycle? Why is it in the ocean?

Answer 23

dissolved phosphorus (PO4^3-), mostly from weathering rock
- can come from the continent (through rivers); explosion of volcanoes; deep-sea vents; bc rock dissolve over long periods of time

^So, basically after geological time, the process arrived at a steady rate in which the dissolved phosphate currently in the oceans is neither increasing nor decreasing; the inputs are exactly matched by the losses (the bowl theory)- phosphorous recycled quickly bc it continuously passing between cells and seawater

Question 24

Phosphorous limited? Why or why not?

Answer 24

It is limited in freshwater (due to diazotrophs), but pretty abundant in surface sea water. The reason is bc phosphorous does not sink with dead organisms to the extent that nitrogen done. Instead released quickly in dissolved forms in the surface waters due to being used for metabolic reactions (to create action) and not cell composition like nitrogen, so its release quickly before dead cells (detritus) reach the bottom, ready to be used for another plankton

It’s also not limited because plankton need only about 1/16 phosphorous atoms as nitrogen atoms

Question 25

Nitrogen? Why is it limiting?

Answer 25

Nitrogen: important and generally limiting before phosphorus.
comes from the atmosphere (N2 gas), makes up 78% of the atmosphere, most of the time it dissolved with O2, C02, and other gases in the surface water, but it can not be used until it goes through a process called Nitrogen Fixation

Question 26

Nitrogen Fixation? How does it occur?

Answer 26

Nitrogen Fixation: the process in which the bond between two nitrogen atoms in N2 are broken, enabling two nitrogen atoms to be incorporated into more bioactive forms (in land & ocean)- it is accomplished through nitrogen fixers or diazotrophs (a specialized group of bacteria and a few species of bacteria-like algae); the nitrogen fixers transform N2 into cellular components of the diazotrophs, such as amino acids and proteins (ex:) making PON (particulate organic nitrogen); when the diazotrophs excrete nitrogen into seawater and when they die, they release a biologically useable form of nitrogen, known as dissolved organic nitrogen (DON).; some of it make be released as NH4+ (ammonium). - if this happens in the surface water, then it may be taken up by phytoplankton and incorporated into cellular materials such as protein, but this rarely occurs bc the cells die, decompose, and sink to the bottom before reaching surface waters

Question 27

What happens to NH4+ (ammonium) at deep waters?

Answer 27

NH4+ ammonium (a production of nitrogen) is produced at the bottom, which is oxidize by nitrite (NO2-) and then nitrate (NO3-), a process called nitrification

Nitrification: only occurs in dark waters and is slow (taking up to week and months to accomplish it); overall, mostly done in deep waters

Question 28

Where is there the most nutrients?

Answer 28

Deep-water concentrations of both nitrate and phosphate increase from the Atlantic to the Indian to the Pacific Ocean, reflecting an accumulation over time and distance as those deep waters traverse the ocean depths as part of the global thermohaline circulation pattern; the oldest deep ocean waters in the world are in the Pacific ocean, those waters have the highest nutrient concentration

Question 29

sediment denitrification?

Answer 29

Certaini kinds of bacteria in bottom sediments of the deep ocean and on continental shelves are capable of converting NO3- back to molecular nitrogen; this process is called sediment denitrification. (that N2 can then make it’s way back to the atmosphere)

Question 30

Amammox? produced? and where?

Answer 30

short for anaeorobic ammonomum oxidation; in which N2 is produced from ammonium and nitrite, was discovered recently

This process occurs in anaerobic sediments and deep-sea vents (where o2 is present) and may contribute half of the world ocean’s total denitrification

Question 31

the two type of upwelling and primary production?

Answer 31

2 types of upwelling
1) wind-driven coastal Ekman upwelling
2) equatorial divergent upwelling
greatest primary production occurs in upwellings

Question 32

Winter convective mixing?

Answer 32

Deep vertical mixing in water at high latitudes; what happens basically is that at those latitudes the upper ocean undergoes a seasonal transition from a relatively warm, shallow, near-surface layer during the warmer months of the year, which is isolated from deeper, colder, and denser waters by a thermocline, to a situation in the fall and winter where the water at the surface gets cold and sinks, and words the thermocline process - which has deep water mixing at the surface, getting enriched with nutrients (production still low)

Question 33

Why that, even after winter convective mixing, are areas of high latitude still low nutrient?

Answer 33

Low bc light levels are low, and the system is light limited; the sun angle is low, the days are short, and the winter column is not vertically stratified and there is no upper ocean thermocline or pycnocline

Question 34

When does the ocean begin to stratify in high altitudes? And what happens to the phytoplankton?

Answer 34

It begins to stratify when the sun climbs higher in the sky, the ocean gain heat at the surface, and thermocline is created; and, the phytoplankton will maintain itself above the thermocline, called the upper mixed layer

Question 35

What provides the energy for the upper mixed layer and where is it in the ocean?

Answer 35

Wind and waves provide the energy to do the mixing in the upper mixed layer. The upper mixed layer is confined with a vertical mixing between the surface and the depth of the thermocline bc there is a thermocline. If mixing was deeper, then the thermocline would be even deeper!

Question 36

When does photosynthesis occur in high altitudes? Nutrients?

Answer 36

During spring, light levels are okay for plankton; and since the nutrients are great already, there can be spring phytoplankton bloom

Question 37

When do we see the height phytoplankton biomass and growth rates of phytoplankton?

Answer 37

at the point where the mixing depth and the critical depth are equal, and continuing afterward as the mixing depth becomes shallower than the critical depth, phytoplankton blooms

Question 38

Secondary production?

Answer 38

After the primary production

Question 39

Productivities in the world oceans? What areas are the most productive?

Answer 39

1) upwelling areas, while open oceans are not due to producing low primary production

even though upwelling is productive, it’s not everywhere, so it’s not that important in the grand scheme of things

Question 40

Trophic levels? Trophic Pyramids?

Answer 40

(Food) Energy gets loss from food as it goes up the food chain or out to the food web (primary production –> secondary etc)

Trophic pyramids: assumes a 10% transfer efficiency

Question 41

Photic zone? What are the two zones in this zone?

Answer 41

Photic zone: defined as the upper 100-200 m or so, the surface waters that are usually sunlit
1) euphotic zone: where there is sufficient light for photosynthesis
2) disphotic zone: where there is sufficient light for vision but not enough for photosynthesis

Question 42

Aphotic zone?

Answer 42

A zone of almost complete darkness; the majority of the ocean is an aphotic zone

Question 43

Pelegic zone?

Answer 43

open water regions of the ocean and includes anything that is in the water and not the bottom of the ocean

Question 44

most marine mammals are cold blooded or warm blooded?

Answer 44

Cold-blooded

Question 45

Basic tree of life?

Answer 45

Archaea, Bacteria, and Eukarya (protista, plantae, animalia, fungi)