Marine Ecology

Question 1

What affects O2 distribution in the ocean

Answer 1

Eutrophication and global warming

Question 2

Describe the relationship between solubility of O2 and temperature

Answer 2

The concentration of dissolved oxygen when in equilibrium with the atmosphere decreases with increasing temperature

Question 3

Where/how is O2 produced in the ocean

Answer 3

In sufficiently light surface waters phytoplankton photosynthesize

Question 4

Where/how is CO2 produced in the ocean

Answer 4

Throughout the watercolumn by respiring organisms

Question 5

Define thermocline

Answer 5

The transition layer between the warmer mixed water of the epipelagic zone and the colder deeper mesopelagic zone

Question 6

Describe the vertical distribution of dissolved O2

Answer 6

In surface mixed layer
Equilibrate with atmosphere
Production through photosynthesis
Loss via respiration
Below thermocline
Can’t equilibrate with atmosphere
Loss via respiration
Supply via circulation

Question 7

What is an oxygen minimum zone?

Answer 7

a zone where O2 saturation is at its lowest

Question 8

What causes oxygen minimum zones

Answer 8

When water renewal very slow and/or

respiration very high

Question 9

Define oxycline

Answer 9

a sharp gradient in oxygen

Question 10

Describe the Oxic level

Answer 10

~ 250-300 mmol O2m-3 Normal aerobic respiration takes places

Question 11

Describe the Hypoxic level

Answer 11

~ 60 mmol O2m-3 – fish, zooplankton stressed and actively select higher oxygen levels

Question 12

Describe the suboxic level

Answer 12

5-20 mmol O2m-3. Denitrification : consumes nitrate, produces nitrogen
reduced zooplankton egg development

Question 13

Describe the anoxic level

Answer 13

oxygen minimum zones and sediments). Sulphate reduction, production of hydrogen sulphide. Methane production from CO2

Question 14

What is eutrophication and its consequences?

Answer 14

Run of of nitrates and phosphates leading to algal blooms which reduces the O2 concentration potentially leading to hypoxic conditions. Nutrient pollution is the single largest pollution problem affecting coastal waters of the United States (Howarth et al., 2000).

Question 15

What two effects does global warming have on the oceans

Answer 15

Decreases solubility and increases stratification

Question 16

What are the consequences of global warming on phytoplankton

Answer 16

Surface warming increases the density difference, or vertical“stratification” of the ocean waters, leading to
less mixing between the surface water layers,
where phytoplankton live, and the deeper water
layers, which contain the nutrients they need to
flourish.

Question 17

What are the 3 oceanic consequences of rising CO2 level?

Answer 17

acidification, warming and deoxygenation

Question 18

What are the main causes of open ocean deoxygenation

Answer 18

a warming ocean, increased stratification and

changing circulation Keeling et al. 2010

Question 19

Consequences of worsening hypoxia

Answer 19

Negative impacts on tourism, food security, ecosystem services and fish catch

Question 20

Causes and effects of upwelling in the US

Answer 20

Intensified wind-driven upwelling related to atmospheric warming and its effect on the depth of waters with low oxygen and low pH, is bathing continental shelves in hypoxic, carbonate undersaturated waters along the US west coast (Freely et al. 2008)

Question 21

Explain the process of OMZ expansion

Answer 21

Climate change causes the oceans to absorb more heat, resulting in less dissolved oxygen at the surface (decreased solubility) and increased stratification
of near-surface waters. This reduces subsurface mixing and transfer of atmospheric oxygen into the water column. . Alterations of oceanic circulation patterns can also reduce ventilation from within
the water column. Keeling et al. 2010

Question 22

What are the 3 main changes OMZ expansion will have on microbial communities

Answer 22

Alteration of the N cycle, the emergence of sulfur (S) cycling, and the creation of new low-oxygen habitats. (Gilly et al. 2012)

Question 23

Example of organisms who will be affected by OMZ expansion and why

Answer 23

It will lead to habitat compression for intolerant demersal, mesopelagic, and bill fishes and habitat expansion of hypoxiatolerant species such as the Humboldt squid. In general . Oxygen exerts tremendous control on marine biodiversity through effects on evolution, physiology, reproduction, behavior, and species interactions

Question 24

What is the relationship between Atlantic OMZ shoaling and tropical pelagic fish

Answer 24

Shoaling may restrict the usable habitat of billfishes and tunas to a narrow surface layer. This habitat compression makes theses predators more vulnerable to surface fishing gear and may be associated with
a 10–50% worldwide decline of pelagic predator diversity. The expansion of the Atlantic OMZ along with overfishing may threaten the sustainability of these valuable pelagic fisheries and marine ecosystems.

Question 25

What causes hypoxic coast lines?

Answer 25

Agricultural fertilizers leaking into the ocean where the
excess nutrients fuel plankton blooms, which
consume oxygen

Question 26

What is the predicted O2 decline in the oceans

Answer 26

1-7% over the next century Keeling et al. 2010

Question 27

Describe the hypoxic situation in Oregon

Answer 27

Off the coast of Oregon, oxygen content in the waters above the OMZ is declining, which may predispose the nearshore waters to hypoxia. As winds push surface water offshore, the low-oxygen, high-nutrient water wells up onto the shelf. The nutrients stimulate the growth of plankton, which use up oxygen when they die and decay. This is has been occurring annually since 2002 to varying degrees of severity (Gewin, 2010)

Question 28

Consequences of ocean acidification?

Answer 28

It will reduce the habitat range of calcifying organisms

because the depth limit at which water becomes corrosive/under-saturated for aragonite or calcite will move upward.

Question 29

What is argonite?

Answer 29

A naturally occurring, crystal form of calcium carbonate, CaCO3

Question 30

How will increased stratification effect benthic biomes

Answer 30

Will reduce POC fluxes to the deep ocean which may further deprive food-poor abyssal plain or organic matter, lowering the benthic biomass.

Question 31

What are the 2 main effects of stratification

Answer 31

Decreasing deep-water oxygen ventilation and reducing nutrient supply to surface waters from the deeper ocean, where organic matter is recycled

Question 32

What are microplastics, specify types

Answer 32

nominally everything less than 5 mm in size
primary – produced in a micro-size range
secondary – fragments of larger plastic materials

Question 33

What are macro/mesoplastics?

Answer 33

plastic nominally greater than 5mm

Question 34

What effects does macroplastic have

Answer 34

Can entangle organisms wound, restrict movement, reduce ability to feed, reproduce and avoid predators. Also can be ingested which can suffocate, reduce/prevent feeding (Gregory 2009)

Question 35

Which bulk plastics are buoyant?

Answer 35

polyethylene and polypropylene,

Question 36

What happens to floating plastic in the ocean?

Answer 36

Floating debris tends to accumulate in the large

oceanic whirls, such as the North Pacific gyre

Question 37

What is the estimation for the current amount of plastic in the ocean and who came up with it?

Answer 37

There are currently 5.25 trillion items of plastic

weighing more than 268,000 tonnes floating around in the oceans (PLoS One (2014)

Question 38

Describe and explain the distribution of plastic waste

Answer 38

There is a similar distribution of floating plastic in both the northern and southern hemisphere gyres. This could be due too removal mechanisms such as plastic washing up on beaches is prevelant enough to keep the distribution equal, even though the north produces more plastic.

Question 39

What is biofouling

Answer 39

The accumulation of biological organisms on wetted surface

Question 40

How could plankton potential reduce plastic waste?

Answer 40

Biofouling may eventually induce the particles to sink
and end up in sediments although whether this route is an important mechanism for the removal of microplastics from surface water is still unclear
Some bacteria have genes that allow for the degredation of hydrocarbons, though it is unclear whether it is at a fast enough rate to be significant

Question 41

What kind of organic pollutants adsorb to microplastics?

Answer 41

polychlorinated biphenyls (PCBs), organochlorines, polycyclic aromatic hydrocarbons (PAHs) and DDTs

Question 42

Discuss the relationship between polyethylene and organic pollutants

Answer 42

The widely used polyethylene has a high propensity to pick up pollutants, which isn’t necessarily a bad thing if it sunk and got stored in the sediment. However they are more likely to act as carrier and introduce the pollutants into the food web

Question 43

How do microplastics effect the environment?

Answer 43

They concentrate low-level pollutants in water. ► These become bioavailable via ingestion to marine organisms.