Marine Ecology Exam 2

Where do biotic factors matter more in structuring the rocky intertidal communities?

Lower intertidal zone

Competition, less habitat space, predators have access to this area

Why might muddy shores be less harsh to live in than rocky ones?

Heat doesn’t vary as much like it does at rock (don’t lose or gain heat as quickly)

What are some morphological and behavioral adaptations to avoiding dessication in the rocky intertidal? 

1) densely packed organisms

2) closed body plan (shell, valve)

3) color of the shells (light, dark)

4) Home scar

5) Protrusions/ridges to radiate heat 

6) Just accostumed to drying out/they can handle it

Zonation

Horizontal banding of organisms

Zones succeed each other vertically

Zonation in the rocky intertidal in scotland

brown algae, fluffy red algae, fucus algae, barnacles, snails

PATTERN IS RELATIVELY PREDICTABLE

Stephenson’s universal scheme of zonation for rocky shores: Does he believe the pattern is unpredictable or predictable?  

Believes the pattern is predictable

What are the physical factors that cause zonation? And do they determine the lower or upper limits of occurence of organisms? 

• dessication

• temperature

• starvation when sessile filter feeders are not covered by water

• lack of larval settlement

• positive interactions such as dense aggregations 

Why are positive interactions helpful when conditions are harsh?

Densely packed organisms can help each other

What are the biological factors that cause zonation?

• competition 

• predation

• grazing (herbivory)

• positive interactions

• recruitment (larval settlement; larvae settled successfully and on track to becoming adults) 

What is the difference in zonation between the wave-exposed and protected New England coasts? 

What is the zonation of the acorn barnacles: Chthamalus and Semibalanus?

• upper limit of chthamalus sis set by physical factors (can’t do it, conditions too hard)

• chthamalus can’t settle lower in intertidal because it will get outcompeted by semibalanus (better at competing)

• chthamalus can tolerate higher temp that semibalanus can’t 

• chthamalus would love to settle all throughout the intertidal but can’t because it is competively excluded by semibalanus

• it is a good thing that chthamalus can tolerate higher temp than semibalanus or it would have no niche 

*Chthamalus tolerates higher temp

than Semibalanus

*Semibalanus is competitively dominant

over Chthamalus

What do you think the relative percentage of biomass is for pelagic organisms? Include bacteria, phytoplankton, zooplankton, planktivorous fish, and predators 

Primary producers: smaller things make up larger percentage of biomass, predators make up fewer 

What are the differences in biomass distribution between pelagic and coastal ecosystems? 

Differences in food webs between open ocean, continental shelves, and upwelling areas?

continental shelves: shorter foodwebs, alternate options

upwelling: short foodweb, whales eat krill directly 

What is the percentage of marine species out of the world species? Of the marine species what is the percentage of benthic vs. pelagic? 

What are plankton, nekton, and benthos and where are they found? 

Plankton: drifters, pelagic

Nekton: swimmers, pelagic

Benthos: bottom dwellers, benthic

Why such a small percentage of pelagic organisms?

Not a great representation of reality, hard to find marine species due to cost, resources needed 

Plankton: Does most biomass on earth consist of plankton?

Yes

Plankton

Phytoplankton are…..

autotrophic

Plankton

Zooplankton are ….. 

heterotrophic 

Are bacterioplankton and virioplankton plankton?

Yes

Plankton

Holoplankton … what life stage are they? 

Entire lives as plankton

Plankton

Meroplankton … life stages

• part of lives as plankton

• juvenile or larval stages

Plankton

Macroplankton …. what are they

Picoplankton ….. what are they

Macro = large floaters such as jellyfish or sargassum

Pico = very small floaters such as bacterioplankton

Nekton

Do they swim? What organisms are they?

• independent swimmers

• most adult fish and squid

• marine mammals

• marine reptiles

  

Differences in swimming abilities of plankton vs. nekton?

Plankton = drift, can’t control where they drift to (in current that they’re in, don’t move out of current)

Nekton = swim, can get out of a current (sharks, fish, cephalopods, sea turtles) 

What two organisms do zookplankton include?

copepods (T shape) and foraminifera.

Do zooplankton (animal plankton) have high or low RE?

Low RE

How do copepods feed? (selective adaptive strategies)

Appendages generate flow to drive plankton to their mouth parts

Are zooplankton grazers in the ocean?

If so, what types?

Yes

1) Protists (single cells): engulf food, narrow size range of food

2) Gelatinous animals: “Hoover” or stick to prey, wide size range of food

3) Crustaceans: “Handle” their food, narrow size range of food 

Chthamalus and semibalanus coexist in the rocky intertidal: what determines their distribution? 

Competition

Give an example of meroplankton

reef fish, jellyfish

Why are copepods and krill important in pelagic ecosystems?

Lots of organisms eat them

What is a main challenge of pelagic organisms?

Must stay afloat

Why is it important for phytoplankton to stay afloat?

Need to get enough light for photosynthesis

(Once sinking or being carried out of the photic zone by water movement, they will likely dies, unless they can somehow get back into the sunlit layer)

Why is it important for zooplankton to stay afloat?

Need sunlight for their bio rhythms and their food is in the shallow water

How do epipelagic organisms float?

Have special adaptations that make them more buoyant:

1) Increased resistance through increased surface to volume (larger organisms)

2) Long projections/spines = inc drag 

3) Store lipids, such as oils or fats (sharks have oily liver) 

4) Pockets of gas (air sacs) 

How do pelagic organisms move?

Some have cilia and flagella

Diel vertical migration

transducer, signal goes down. How quick signal bounces back depends on how deep the organism is/ if it is hard or soft

As surveys progress, approach night plankton that come up to the surface the krill will swim up to where the phytoplankton is at the surface

Diel vertical migration (DVM) is the daily, synchronized movement of billions of marine animals from the deep ocean to the surface and back down again. This phenomenon occurs as animals ascend to the surface to feed under the cover of darkness and descend to deeper waters at dawn to avoid predators, making it the largest migration on Earth

How does organic matter get to the bottom of the ocean?

Dead cells and fecal pellets (plankton poop) sink, big ones sink faster

Dissolved organic matter, pieces of gelatinous animals etc. stick together and form bigger “marine snow” that sinks 

The organic debris is collectively known as Detritus 

Marine snow formation how?

While photosynthesizing DOM is exuded

These molecules encounter one another in the aqueous environment 

Opposing charges bring the particles together to form larger particles

The particles are extremely sticky and easily adhere to each other as well as other particles in the water 

Where does most of marine sediments come from? What are the diff types of sediments? 

Type   Source

Terrigenous   pre-existing rock

   (or Lithogenous)   all land derived material

Biogenous  living organisms

Hydrogenous  precipitation from sea water

Cosmogenous  space

North Atalntic Spring Bloom: Productivity patterns, what happens to phytoplankton and zooplankton?

Drop in phytoplankton in April/May (bloom of phytoplankton then eaten by predators)

Mixing = nutrients brought down to lower levels to help productivity

How does productivity impact fisheries yield?

Inc in primary production = inc in fisheries yeild

amt of primary production differs btwn locations (upwelling zones = high PP bc getting deep sea nutrients)

Eutrophic = top of graph, high nutrient availability 

Oligotrophic = bottom of graph, low nutrient availability 

Main takeaways of Menge, Daskalov, Hacker, Silliman, Hughes, Fugiwara papers

Hacker and Bertness identified a potential positive interaction in salt marshes. What was it? 

Plant species fixed soil for other species therefore diversity is a lot higher (ex. plant reduces salinity which improves the conditions for other plants) 

Silliman’s study change a widely held idea about salt marsh communities. How?

Showed that predators impact trophic cascade. It is actually a top-down cascade 

What is the origin of the majority of deep sea sediments?

From surface (biogenious) things that drift down, dead organic matter/detritus

Explain these patterns:

Nutrients high in deep zone because of dead organic matter

Things that can take advantage of nutrients are in short zone (why nutrients low) 

Phytoplankton producing oxygen, oxygen dissolving into ocean water/high gas exchange (why oxygen high in low zone)

No photosynthesis/no new oxygen produced and high respiration/org eating DOM (why oxygen decreases in midd zone)

cold dense water masses/oxygenated water sinks to bottom (why higher in bottom zone)

no primary producers to consume nutrients (why they accumulate in bottom zone)

Overall trend: 

• Surface: Life uses nutrients and sunlight to produce oxygen (photosynthesis). (Nutrients dec, Oxygen inc)

• Middle/Deep: When that life dies and sinks, the process of decomposition uses oxygen to release the nutrients back into the water. (Oxygen dec, Nutrients inc)

What happens to oxygen/nutrients in pelagic environments: Where is it dissolved? Where is nutrient max? Where does oxygen inc? 

Dissolved O₂ minimum layer about 700-1000 m

Nutrient maximum at about same depths

O₂ content increases with depth below

Coriolis effect

Explains why we have general clockwise movement of water in the Northern hemisphere and general counterclockwise movement of water in the Southern hemisphere 

Ekman transport

Ekman transport is a fundamental concept in oceanography that explains how wind drag on the ocean surface translates into net water movement at an angle to the wind, due to the influence of the Earth's rotation (Coriolis effect).

The wind pushes the surface water

The rotation of the earth deflects the water.

The result is a net, 90 degree movement of the water relative to the wind (N: 90 to right, S: 90 to left) 

How does Ekman result in upwelling?

Ex. along west coast the net water movement is 90 to the left. Wind is coming down south

The water that is moved to left is replaced by deep ocean water (upwelling). Cold bottom water comes up along continental shelf, nutrients available in coastal zone: phytoplankton can now eat, zooplankton can now eat phyto, big fish eat zooplankton etc (imp for commercial fishing/food webs) 

Helical vortices how do these impact nutrient flow? 

Ocean mixing due to wind allows nutrients to come to surface, oxygen to go down deeper

El nino vs. La nina patterns

El Niño (La Niña) is a condition in the Pacific ocean and characterized by the cyclic warming (cooling) of the central and eastern equatorial Pacific (CEEP).

El nino = warmer than normal 

La nina = cooler than normal 

How do they see if it is el nino or la nina?

Specialized buoys

Southern oscillation

Southern Oscillation is the atmospheric component of ENSO (el nino southern oscillation) and measured in terms of the difference in standardized pressure anomalies over Tahiti and Darwin, and  wind anomaly at low level winds (850 mbs level).

Pressure differential

What does ENSO in tropical pacific look like, what are the weather patterns? 

Clouds = wet weather

Feature	El Niño (Warm Phase)	La Niña (Cool Phase)
Equatorial Pacific SSTA	Warmer than average	Colder than average
Trade Winds	Weaker or reversed (blow East)	Stronger than normal (blow West)
Warm Water Location	Shifts eastward toward South America	Piles up in the far Western Pacific
Upwelling	Suppressed (Warm surface water blocks cold, nutrient-rich water from rising)	Enhanced (Stronger winds push more surface water away, increasing upwelling)

Impacts of ENSO and Non-ENSO on Phillipine annual rainfall

Red = El nino

Blue = La nina

Red = drought 

Blue = wet 

FADS - Fishing aggregating device

Why the phenomenon? 

Manmade object put in middle of ocean to attract fish

Phenomenon = Fish accumulate around things floating on surface (debris, algae etc) 

Why? Shelter, protection (structure offers refuge), potential food source, currents/forces that cause thing to be there will bring nutrients with them (evolutionary adaptation)

Meeting place hypothesis: let’s meet at object and we’'ll find other members of same species to mate with 

Why is oxygen at a maximum at the ocean surface? Why are nutrients so high on the ocean floor?

Diffusion

DOM

What are the consequences of the Coriolis effect?

Dense patches of garbage

Ekman transport (wind against water w/ friction) which causes upwelling

Why do we care about el nino? 

Has an impact on fishery productivity 

Effect on agriculture (flooding or drought depending on where you are)

The LNG project

Compressed natural gas on ships goes into the buoy as decompressed gas, which then goes into tubes

Hypothesis: more fish at buoys because of structure FAD 

What was result of LNG project

no diff in density of fish btwn controls and structure

Pattern of acoustic imaging: not oversampling one area, interior & exterior being sampled equally (no time bias) 

What is the distribution of benthic organisms? And why?

žMore benthos beneath areas of high primary productivity

žMainly on continental shelves

žAffected by surface ocean currents

More biomass on coast (nutrient availability higher), more shallow water (warmer + sunlight), more structure 

Anatomy of the continental shelf: POM, DIN, DOM

Shallow continental shelf habitats: predators or scavengers

žMany generalists in the benthos including many facultative scavengers (if they have opp they’ll do it but don’t need to)

žSome organisms rely on dead material and are tolerant of low food periods

What types of grazers in benthic areas? Why are they important? 

Herbivores include fish and invertebrates and encrusting inverts. Grazers are often important habitat modifiers, removing dominants that would otherwise take over 

Fish are primarily herbivorous at lower latitudes. Why?

benthic continental shelf fish are more commonly herbivorous due to a combination of high water temperatures, abundant plant-based food, and co-evolutionary relationships with coral reef ecosystems

Particle feeders often drive benthic/pelagic coupling. What does that mean?

Energy/nutrients in pelagic, suck it in and turn it into larvae and feces in benthic habitat (tunnicates do this) (bring pelagic nutrients and energy to the benthos) They filter tens of liters of water per day 

Why is particle feeders feces important? And where are particle feeders more abundant? 

žFeces provide a rich substrate for microbial communities

žTend to be more abundant in shallow water where phytoplankton are abundant

What are bioturbators and d4 examples?

Burrowing into sediment 

Callianasid shrimp, echiuran worms, predatory seastar, bobbit worm 

What is bioturbation and who is doing it?

Turning over of the sediment and increasing sediment oxygen content

Can be surface bioturbators or burrowing 

Often deposit feeders 

What is a species assemblage?Sediment functional groups 

What is identity of species in a particular place (a group of different species that coexist in a particular location and time) 

Different assemblages, same role

Why are hard bottoms rare and densely populated?

—Organisms tend to be larger, taller

easy to grab on to

WHat might limit the use of hard bottom benthic habitats?

No refuge, burrowing limited

How does softness of sediment relate to biodiversity? What limits their depth? 

žThe softness of sediment and particle diversity are directly related to the variety and number of infaunal organisms

O2, pressure 

Substratum influence on biota distribution? How far can they be above or below the sediment?

žBiota can extend up to two meters into the benthos and about 50 m above it

What influences the substratum? 

Flow

High flow creates hard sediment, and low flow creates soft sediment. The force of the water determines the size and composition of the particles that are moved and deposited. The process involves both erosion (wearing away) and deposition (dropping off)

Upwelling can bring diff nutrients

What is majority of biomass in continental shelf zone?

Bacteria

Epifaunal effects

Epifaunal effects refer to the ecological roles of benthic animals that live on or are attached to a surface, such as the seafloor, rocks, or vegetation.

Epifauna are capable of influencing the water column by modifying flow and depleting resources

Ex. phytoplankton depleted by mussel filtration over time 

You’re on the open ocean and you want to catch some fish. What might you look for and why?

Garbage, structures 

Fish meeting point

Why might benthic pelagic coupling be important when it comes to biomass and diversity of continental shelves?

by connecting the seafloor (benthic) and the water column (pelagic) habitats. This exchange of energy, mass, and nutrients drives key ecological processes that support vibrant food webs and a wide variety of life. The coupling is especially strong on continental shelves because of their relative shallowness compared to the open ocean, which facilitates the transfer of organic matter and nutrients. 

What influences sediment/substratum type on the continental shelf benthos?

Flow 

Deep sea diversity: There are clear latitudinal trends in species richness/diversity. Why? 

DOM and nutrients coming from productive areas above

What unique factors influence the biomass and diversity of the Cordell bank? 

• relatively shallow 

• right at oceanic edge where shelf drops off (upwelling of resources) 

• things abundant in blue water pelagic coming close

• hard substratum (typically not common in deep sea), this allows photosynthesizers to latch on, as well as suspension and filter feeders

What threats are faced by the cordell bank national marine sanctuary? 

inc temp from climate change → dead zones where O2 is depleted 

Presistent ocean current patterns:

Currents converge toward Equator following Trade Winds and ITCZ

Westward flow along Equator (i.e., North and South Equatorial Currents)

Equatorial Currents turn poleward where they encounter land barriers (e.g., Gulf Stream)

Eastward flow of currents is enhanced by the Westerlies (wind)  

Currents turn toward the Equator where they encounter land barriers, completing the gyres

Effects of surface currents, diff btwn poles and equator?

More solar heating and evaporation at Equator, less at Poles à salinity and temperature Equator/Pole gradient

Warm and salty water carried poleward

Deep currents: what does salinity and temp mean for density? What is the conveyor belt? 

A. Thermohaline-driven currents

1. Greater salinity=greater density

2. Lower temperature= greater density

3. Equilibrium is sought in global-scale deep currents (conveyor belt = slow and is driven by evaporation and gain of water by precipitation and terrestrial runoff)

Is more of earth’s surface above or beneath sea level?

A lot right at sea level but majority beneath

What depth is the deep sea?

Below the euphotic zone (200m+) and the shelf break

Deep sea: where do the sediments come from?

terrestrial and biogeneous materials

Oxygen uptake in deep sediemtns is 2 orders of magnitude lessthan shelf sediments. Why? 

Lack of biological activity of living org that use O2 due to cold (low density of org) 

Deep sea vocab

What are the abiotic factors in deep sea systems?

• High pressure (1atm/33ft) 

• Low temperature (from -1 and 4^◦C)

  Total lack of sunlight

  Lack of photosynthesis

  Scarcity of food resources

  Enormous volume of water further reduces encounter probability (mates, prey)

Distribution of benthic org?

Very low biomass in deepest parts of ocean, higher biomass at continental shelves 

What percentage of the sea floor is below 3000 m depth?

75%