Marine Ecology Exam 1

Physical _______________ can play a disproportionate role in limiting the distribution of organisms, and can set the __________ of where organisms can live. 

1. environmental extremes

2. outer limits

Physical environment alters _____________ for many ecological processes.

Interaction strength

Physical Drivers (6)

• light regime

• temperature regime

• hydrodynamic regime

• chemical regime

• mechanical disturbance

• gradients & rates of transfer

Interactions between physical context and species occur at _______________. Variability of conditions across _______ and _______. 

• several spatial scales

• space and time

Biomechanics

How the flow of water affects the body of an individual

Molecular diffusion

Quantifies the rate at which particles disperse from areas of higher to lower concentration

What is molecular diffusion influenced by?

• Temperature

• Viscosity

• Particle size

How does viscosity affect marine ecological processes?

• How animals move/sink

• How drag affects seaweed or coral shapes

Seawater’s viscosity changes with ________ and _______, which in turn influences organism ______ and _______ use. 

1. temperature and salinity

2. behavior and energy

Specific Heat

How much heat you need to raise 1 g of a substance by 1 degree

Reynolds Number

Relative importance of inertial & viscous forces and consequences of their relative importance

Does this organism have a high or low Reynolds number? Why?

• Low

• Environment is very viscous

Does this organisms have a high or low reynolds number? Why?

• High

• Environment is very fluid

What are the 3 key forces?

• Drag

• Lift

• Shear

What is drag?

The force that acts opposite the direction in which the organism moves

How does drag affect motile and sessile organisms?

• Sessile: can cause dislodgment/breakage

• Motile: takes more energy and streamline to reduce drag

What is lift?

A force that acts in a direction perpendicular to the flow and is upward in most situations. Results from lower pressure on the top than bottom.

What is shear?

How much the water moves at different speeds along the height of an organism

Turbulisors

Used by pelagic fish to delay boundary layer separation. Use at the widest point of their body to induce turbulent flow

What is a boundary layer?

Distance over which the object reduces the free stream velocity 

What is the boundary layer influenced by?

• Size, rugosity, flow speed, fluid density and viscosity

Fast currents ______ the thickness of boundary layers, whereas weak currents _________the thickness of boundary layers. 

• reduce

• increase

What is Benthic boundary layer?

Large-scale boundary layer over the sea floor

What is momentum boundary layer?

Forms around each object/organism

What is the diffusion boundary layer?

Thin viscous layer very close to each object/organism where there is very little fluid motion and diffusion/conduction are the only transport mechanisms.

Organisms exchange heat, gases, and nutrients with their environments via _______

Gradients

Gradients can be created by (2)

• Organism

• Shaped by environment

Exchange happens without a gradient (T or F)

False

Heat flows from ______ to ______ areas

warmer to colder

Intertidal organisms face temperatures __________ higher than surrounding area

10-15 degrees

Greater flow _______ DBL and _________ mass transfer, which can enhance various biological processes

• reduces

• enhances

Particle flux =

flow velocity x concentration

If flow velocity is too high, prey capture/retention is _________

compromised

If flow velocity is too low, a _______ concentration of food is required to achieve the same flux

higher

Increasing turbulence can ________ the detection range and probability response by both predator and prey

decrease

What is dispersal?

Movement of individuals of a population away from their native habitat

Roughly ____% of all marine organisms have a biphasic life cycle and produce planktrophic propagules

80%

Dispersal among populations links them together is called a __________

metapopulation

What is important about dispersal?

• Some populations act as larval sources, sustaining others

• Species distribution range

• Colonization of new habitats

What are the biological determinants of dispersal spread?

• Pelagic larval Duration

• Larval feeding/behavior

• Adult behavior

What are the oceanographic determinants of dispersal spread?

• Temporal variation in ocean conditions

• Habitat patchiness

• Retention vs immigration

What are the ecological determinants of dispersal spread?

• Selection for/against immigrants

• Population size

3 Basic modes of larval development

• Direct

• Lecithotrophic

• Planktotrophic

Direct larval development

• No larval stage

• Internally brooded

Lecithotrophic larval development

• non-feeding larval stage

• Do not require food to complete development

• Short PLD

Planktotrophic larval development

• Feeding larval stage

• Incapable of completing development w/o feeding

• Long PLD

Direct: Larval mortality

• Protected eggs

• High survival rate

• physical/chemical defenses

Lecithotrophic: Larval mortality

• physical/chemical defenses

• intermediate survival rate

Planktotrophic: larval mortality

• Few defenses

• low survival rate

Episodic regions of enhanced shear and vertical velocities such as _____, ______, ______. Accumulate passive, buoyant particles and weakly swimming organisms

Fronts, eddies and upwelling zones

Increased primary productivity and concentrated food biomass may ______ larval development and _____ PLD

accelerate and shorten

For actively swimming larvae, temporally varying patches of prey may _______ survivorship and _______ aggregation.

enhance and promote

Davidson current dominates in the _______

winter

Coastal upwelling dominates in the _________

Spring

Eddies & recirculation gyres dominate in the ________

Summer

Relaxation of winds and upwelling occur in the ______

Fall

Isolated patches = local retention, what kind of population?

Closed

Continuous patches = more immigration, what kind of population?

Open 

What factors influence larval retention?

• low PLD

• Ocean currents

• Habitat patchiness

Locally-sources individuals sometimes survive and reproduce better than immigrants due to ____________, which reduces effective connectivity even when dispersal is high

local adaptation

Benefits of MPAs?

• Adult & larvae spillover

• Population spillover

Intertidal

Between the tides

Littoral means

shore

What is semidiurnal tide?

2 high tides & 2 low tides

What is mixed tide?

Two high and two low unequal tides

What is diurnal tide?

1 high tide, 1 low tide

Types of intertidal communities (5)

• Rocky intertidal

• Soft sediment

• Estuaries

• Salt Marshes

• Mangroves

Extent of gradient between ocean & land will often be determined by _______

wave size

What causes zonation in intertidal communities? (3)

• Physical limitations

• Settlement patterns

• Biotic limitations

What is the most likely physical factor determining zonation?

Tides

What are physical factors? (4)

• Tidal cycle

• Wave action/exposure

• Temperature/UV

• Substrate types

Pacific Coast has more _______ intertidal communities while the Atlantic coast has more ________ sediment intertidal communities

• rocky

• soft 

Define Littoral zone

Between the highest and lowest spring tides

Define Supralittoral zone

• splash/highest zone

• dominated by periwinkle snails & lichens

Define midlittoral zone

• Upper limit: barnacles

• Lower limit: kelp

Upper midlittoral

• Only covered by water at high tide

• Dominated by: algae, barnacles & periwinkle/turban snails

Middle midlittoral

• Regularly covered by water 

• Dominated by: rock weed, mussels, turban snails & barnacles

Lower midlittoral

• Usually submerged, only exposed at very low tides

• Dominated by: algae, sea anemones, stars & urchins

What is the SST year round in HI ocky intertidal?

24-28 degrees

What is HI’s zonation?

• Supralittoral

• Mid-intertidal 

• Lower intertidal

What are physical adaptations in intertidal? (7)

• Aggregate, seek shelter, orient away from sun

• Evaporative cooling

• Light color

• Sculpture, thick & ribbed shells

• Heat shock proteins & antifreeze

• Strong attachment

• Flexibility

• Rapid reattachment

Upper limits are determined by ____ factors

physical

Lower limits are determined by ______ factors

Biological

The __________ is the portion of the fundamental niche to which an organism is restricted by factors such as predation, competition, pathogens, etc.

Realized niche

Keystone species concept

Species whose effect on its community is disproportionately much greater than its abundance alone

Top down control

______ plays a major role in structuring some biological communities

Disturbance

Equilibrium

Absolute and relative abundance of sp remains constant and is balanced by intra-and interspecies interactions

Nonequilibrium

There is a balance of absolute and relative abundance globally, but locally, equilibrium is prevented by periodic stochastic disturbances

Intermediate disturbance theory

Local populations are not in equilibrium, but are disrupted by disturbances

Higher disturbance =

Lower chance of secondary & late succession/colonization