Marine Ecology, March 31, April 2&4, 2008

Abiotic factors: General and intertidal

It’s all about the water! Origin of water on earth Polarity of water Hydrogen bonds and associated

properties Density-temperature relationship and

its importance Water as the universal solvent

What is the origin of water on earth?

Water molecules

Polarity Hydrogen bonds Cohesion & surface

tension

Hydrogen bonds and temperature

High heat capacity Much heat needed for

state or temperature change

Liquid over a wide temperature range

High latent heat of melting

High latent heat of evaporation

Density: Max at 4ºC

What are the consequences of this density maximum?

Water as the universal solvent

What makes water such a great solvent?Key: Polarity!

Other important abiotic aspects of seawater

Salinity (list of solutes) Temperature (range, variability) Nutrients (types, why important) Dissolved gases pH (effects of respiration and photosynthesis) Light (importance) Pressure Water movement (major currents, upwelling) Substrate

Dissolved ions/salinity

Sources of dissolved ions

Average salinity33-37 ppt

Many of these ions have important physiological roles.

Salinity and estuaries

Temperature

Range of 28-212°F (-2-100°C) Highest at hydrothermal vents

Temperature and organisms Brief example: coral reefs

Surface water temperatures (global)

Vertical profiles of temperature, salinity, and density

Be sure you understand how temperature and salinity affect density and layering!

Nutrients

Key dissolved nutrientsInorganic nitrogen (i.e. nitrate, ammonia)Inorganic phosphorous (i.e. phosphates)Inorganic silica (i.e. silicates)Iron (various compounds) Dissolved organic material (DOM)

Major rolesPrimary production/biomolecule synthesisExcess nutrients may be problematic…

Distribution of primary production mirrors nutrient distribution

Dissolved gases

Oxygen, carbon dioxide, nitrogen Ocean has 50 times the levels of

CO2 as the atmosphere! Levels of O2 and CO2 affected by:

Exchange with atmospherePhotosynthesisRespirationMovement of water masses

Vertical distribution of O2

Know how and why O2 varies with depth!

pH: -log [H+]

Depends on dissolved elements & molecules

Seawater has pH of 7.6-8.6 Generally stable in ocean waters: Diffusion/water movement/carbonate buffering

prevent drastic changes Addition of CO2 (i.e. respiration): pH Decrease of CO2(i.e. photosynth.): pH In closed aquaria: build-up of organic

acid waste products pH

Light

Primary energy source for producers (except at vents)

Loss of light with depth Wavelength/color

dependent Depends on

particulates

Pressure

Increase of 1 atmosphere/ 10 m

Various impacts on organismsExample:

impact on air spaces

Ocean circulation

Ocean currents are wind-driven

Coriolis effect causes deflectionEkman spiral Ekman layer

moves 90º to right from wind direction in N hemisphere; 90º to left in S hemisphere

Major surface currents

Note major ocean gyres

Sea surface temperature (SST) revisited

Notice effects of cold vs. warm currents

Upwelling: West coast of North America

Key global upwelling zones

Great ocean conveyer

Time scale: 4000 year turnover Key: salty, cold water sinks near Greenland

& Antarctica; brings oxygen to depths Ice formation contributes to high salinity; air

temperatures are cold

Waves

Caused by wind; become higher and shorter close to shore

Shallow organisms most affected Particles move circularly within waves

Substrate!

Mud, rock, sand, etc… Different survival strategies

in different substrates

What causes the tides?

Moon’s gravity“Pulls” water

toward it Rotation of

earth/revolution of moonCentripetal force

creates near-equal, opposite bulge

Why are their usually two high tides and two low tides each day?

And why are they 50 minutes later each day?

The sun’s effect: “spring” tides and “neap” tides

The tilt of the earth

This causes the two high tides and two low tides each day to be of unequal height

General patterns of zonation (Pacific)

Upper intertidal: submerged only on high-high, spring tides.

Upper intertidal

Ligia sp. (rock louse)

Littorina sp. (periwinkles)

Middle intertidal (upper zone): exposed to air more than water, but submerged at least 1x per day

Middle intertidal (upper)

Pelvetia/Fucus (rockweed)

Mid-intertidal: Usually submerged 2x per day, exposed 2x per day (generally submerged a bit more than exposed)

Middle intertidal (lower)

Mytilus californianus: California mussel

Low intertidal: Submerged except during low-low, spring tides.

Lower intertidal

Strongylocentrotus franciscanus: red urchin

Physical factors affecting distribution of organisms

Extent of tidal exposure Amount of wave action Exposure to direct sunlight Temperature Substrate Other characteristics of water

(see previous lecture)

Adaptations to the physical environment

Trapping water within

Limpets and others: clamping down

Barnacles and snails: Trap doors Called an “operculum” in snails

Anemones and snails: closing up

Algae: mucopolysaccharides

Adaptations to the physical environment (cont.)

Microhabitat refuges

Physiological adaptations

Be able to provide specific examples for each!