Marine Ecology, March 31, April 2&4, 2008 Abiotic factors: General and intertidal
Dec 21, 2015
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!