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 salinity  ppt

Many of these ions have important physiological roles.

Salinity and estuaries

Temperature Range of °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 nutrients  Inorganic nitrogen (i.e. nitrate, ammonia)  Inorganic phosphorous (i.e. phosphates)  Inorganic silica (i.e. silicates)  Iron (various compounds)  Dissolved organic material (DOM) Major roles  Primary production/biomolecule synthesis  Excess nutrients may be problematic…

Distribution of primary production mirrors nutrient distribution

Dissolved gases Oxygen, carbon dioxide, nitrogen Ocean has 50 times the levels of CO 2 as the atmosphere! Levels of O 2 and CO 2 affected by:  Exchange with atmosphere  Photosynthesis  Respiration  Movement of water masses

Vertical distribution of O 2 Know how and why O 2 varies with depth!

pH: -log [H+] Depends on dissolved elements & molecules Seawater has pH of  Generally stable in ocean waters:  Diffusion/water movement/carbonate buffering prevent drastic changes Addition of CO 2 (i.e. respiration):  pH Decrease of CO 2 (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 organisms  Example: impact on air spaces

Ocean circulation Ocean currents are wind-driven Coriolis effect causes deflection  Ekman 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 moon  Centripetal 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!