coral health is highly dependent on
phytoplankton algae that provides nutrients for slow growing coral. algae are expelled by coral when the temp. gets too warm (24 C), so color of reef reflects color of underlying (dead) coral (white).
coral polyps
living creatures, calcite substrate is their home.
coral symbiosis
- partnership goes back to the Triassic 210 Mya.
- corals lived in relatively nutrient-free regions, not unlike today’s subtropical regions.
- dinoflagellates (algae) live inside the coral’s tissues.
- the algae perform photosynthesis to produce nutrients.
- the coral in turn emits waste products in the form of ammonium, which the algae consume.
- this prevents vital nutrients from drifting away in the current and allow both species to thrive in nutrient-poor water. coral really took off with symbiosis.
- symbiotic corals outperform non-symbiotic corals 10-1.
dinoflagellates (brown algae)
can swim free with their tail. when they incorporate into coral, they lose their tail. they can be ejected into the water by the coral if stressed. this causes the coral to turn white and begin to starve. if good conditions return soon enough, the dinoflagellates can return to the coral, if not the coral polyps die.
symbiodinium reach
high cell densities through prolific mitotic division in the endodermal tissues of many shallow tropical and sub-tropical cnidarians.
coral bleaches in
el nino years and with global warming.
1997-1998 El Nino and coral
16% of all coral were damaged. Some bounced back. corals could become rare on tropical and subtropical reefs by 2050 due to the combined effects of increasing CO2 and increasing frequency of bleaching events.
by 2030 or 2050, bleaching thresholds will be
exceeded annually or bi-annually at the majority of reefs worldwide.
value of coral reefs in the US
NOAA estimates the commercial value of US fisheries from coral reefs is over $100 million. revenues from diving tours, etc. based near reef ecosystems are in the billions. sources of medicine.
more possible ocean changes due to temp.
- increased disease in fish
- poleward movement of some species (tuna, marlin, cod)
- increased mortality of winter flounder eggs and larvae
- marine mammals, birds, seals, sea lions, and walruses feed mainly on plankton, fish, & squid and are vulnerable to changes in prey in response to climatic factors.
- nesting of sea turtles is strongly affected by temp.
the blob
unusually warm SST off the North American west coast in 2013-2014.
blob associated visitors
mola (ocean sunfish), thresher sharks, etc. both are often associated with warmer waters.
ocean acidification
carbon dioxide can dissolbe in water.
- carbonated drinks: pressurized CO2 is dissolved in water. when opened at normal pressure, it releases CO2 bubbles.
- higher atmospheric CO2 means more CO2 dissolves in seawater.
chemistry of ocean acidification
when CO2 is dissolved in water, some carbonic acid is formed (H2CO3). water becomes more acidic (less basic). the pH of the ocean has been decreasing as CO2 levels have risen.
ph scale
7: pure water
8. 16: sea water (historical)
2050: 7.95
2100: 7.82
how much more acidic is the ocean?
pH is a logarithmic scale, so the observed drop in pH corresponds to 30% more hydrogen ions. significant change.
calcium carbonate
what marine organisms of all types use to build shells, skeletons, etc. reacts with acid
creatures affected by acidic reactions
clams, lobsters, and even low on the food chain organisms like phytoplankton are affected. phytoplankton are responsible for 1/3 of all photosynthesis on the planet and feed the marine food web.
ocean acidification is likely to impair
shell formation in plankton and corals.
increasing the acidity of the ocean has a
negative impact on many types of biology.
puget sound
- suffers from pollution. mostly from street runoff, sewage, and industrial point sources easier to control.
- suffers from anoxia (no oxygen) in some regions (Hood Canal) and seasons (summer), much of this has to do with nitrogen fertilization. too much fertilizer, robust plankton bloom, plankton dies, sinks and rots taking up oxygen and releasing CO2. this gives anoxic, acidic water => animals die.
- suffers from acidification. locally worse than global ocean for same reason as anoxia.
goose bay oyster company
- puget sound and coastal waters of WA and OR are prime oyster farming area.
- since 2005, farmers have had trouble getting the larval phase of the baby oysters to survive, either in natural conditions or in hatcheries.
- increasing evidence has pointed to ocean acidification as a possible cause.
- the company moved their hatchery to hilo hawaii to get better water for their oysters to get past the hatchery phase.
- those hatched in hilo grow up in willapa bay and puget sound.
trends in salinity
change in ocean salinity whereaby salty is getting saltier and less salty is getting less salty. more evaporation than precipitation = more salty (vice versa).
salinity trends
- big. mean value is 34, but contrast in tropics in subtropics is 36-34 ~2.0, trends over 50 yrs are +- 0.2 10-20% of contrast.
- the trends have a similar shapre as the climatological distributions, which are driven at the surface by freshwater flux (E-P).
- argued that the trends are driven by increasing contrast within the hydrologic cycle => P-E is getting bigger in absolute value.
- the surface changes penetrate to depth by mixing along surfaces of constant density.
- this change is consistent with the prediction of climate models that wet gets wetter and dry gets drier.
