Biggest Impacts to Reef Ecosystems: Climate Change or Fishing?

[Crabby]

During the question/answer session at the Fenner talk, I mentioned the recent paper on relative impacts of direct impacts of human activities through overfishing and habitat modification vs. indirect impacts of human activities through climate change on the health of Hawaiian coral reefs in the main and northwest Hawaiian islands. This is the only study I know of that separates direct and indirect human impacts on marine ecosystems. The take-home message is that while climate change is happening and has the potential to impact marine systems, the direct impacts of humans through fishing, habitat destruction, pollution, etc.. have vastly larger impacts. Thus, in the face of climate change, it's even more important to moderate our own activity that directly impacts these ecosystems.

Kittinger JN, Pandolfi JM, Blodgett JH, Hunt TL, Jiang H, et al. (2011) Historical Reconstruction Reveals Recovery in Hawaiian Coral Reefs. PLoS ONE 6(10): e25460. doi:10.1371/journal.pone.0025460

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025460

Compare Figure 3A and Figure 3B. In the northwest Hawaiian Islands (3B), coral reefs are recovering while climate change is increasing but human activities have been minimized.

(and sorry - just noticed I posted this as a chain...oops.)

 

[bayview]

http://scienceandpublicpolicy.org/originals/co2_coral_warming.html

Seems to echo that the earth goes though different temperature and c02 levels and corals reefs still grow ... where they are not growing well is when we live by and or pollute the ocean.

 

[rygh]

Hmm...
From studies around volcanic vents that spew out CO2, the data is really clear.
When CO2 drives the PH below 7.8 or so, the reefs are toast.
Google : "volcanic co2 level effect on reef"

Now of course, how long it takes atmospheric CO2 to push PH to that level
is controversial and debatable. Some say 50 years, some say longer, some say never.

My opinion: The current minor CO2/PH changes do not really affect corals, and some slightly
warmer water actually increases growth. So - if you just look at the short term, it all seems fine.
Then stir in some politics...

 

[Crabby]

The data from volcanic events are pretty neat, but one thing that is not always well communicated regarding those environments is that the pH/pCO2 variability is enormous. So, whether the ecological effects observed are due to smallish changes in mean pH, or transient exposure to really low pH (< 7) is something that requires further investigation.

 

[Not_Now_John]

http://scienceandpublicpolicy.org/originals/co2_coral_warming.html

Seems to echo that the earth goes though different temperature and c02 levels and corals reefs still grow ... where they are not growing well is when we live by and or pollute the ocean.

No doubt the Earth has gone through temperature and CO2 changes, and yet corals are still here. The question is-- can corals adapt fast enough if the environmental changes occur as quickly as some of the models predict.

Also consider the source...
http://blogs.nature.com/climatefeedback/2008/08/more_for_the_annals_of_climate_1.html
http://motherjones.com/environment/2009/12/dirty-dozen-climate-change-denial-11-idso-family%20%20

 

[bayview]

I would like to think they can; now humans on the other hand ...

I didn't look closely into the article; I agree it is a questionable source ... I was just trying to get at that I know the c02 levels are higher in the bottom level of my house wit the tanks enough to drop my ph to 7.9 (tank upstairs is 8.2) ... but as long as I drip acclimate the livestock I haven't had any issues ... only thing I really noticed is that the the algae grows faster when nitrates or phosphates get introduced. So I can see how water pollution and higher c02 levels = a big problem. Maybe they should ban septic systems in Hawaii and oceans rather than the reef trade.

 

[Gomer]

No doubt the Earth has gone through temperature and CO2 changes, and yet corals are still here.

The same corals? I don't know the answer.

 

[Not_Now_John]

Maybe they should ban septic systems in Hawaii and oceans rather than the reef trade.

Probably a good idea. Did you see this article on advanced aquarist? Scary and gross at the same time.

http://www.advancedaquarist.com/blog/human-feces-blamed-for-elkhorn-acropora-disease.-yikes

 

[Not_Now_John]

No doubt the Earth has gone through temperature and CO2 changes, and yet corals are still here.

The same corals? I don't know the answer.

Who knows? We can't even tell if living corals are the same species half the time. I mean corals are eternal in theory right? But at what point do subtle mutations add up enough to be a new species? And who knows how much sexual reproduction happens.

 

[aqua-nut]

The issue with global warming is it's speed of change. If climate studies are to be believed, this is the most rapid change in CO2 concentrations in a LONG time. Can organisms adapt fast enough?

If GW is the only stressor, perhaps. It seems we (humans) are doing many things that stress the oceans. Pollution from human and agricultural run-off is most likely another major factor.

Getting action like no septic in Hawaii will be really hard. There is the real economic pressures to resist this change and it is so hard to convince even well meaning people there is a need. Science presents such a unclear and uncertain view of the world. Dogma presents such a clear and certain view. It's much easier for many to believe dogma.

"There is no truth, only perspective."
Signature line I 'lifted' from SFBAAPS contributor.

 

[rygh]

Think it is bad now.
It is highly probably there is another big threat coming.
Farming of seaweed and kelp for bio-fuel!

There have been some breakthroughs recently in bacteria breaking down seaweed.
So the concept is simple. You set up some semi-floating substrate, over
a few square miles out at sea. Then pump semi-treated sewage from a city out to it. Mega-nitrates.
Maybe add a bit of special minerals and phosphates.
Then harvest and turn into bio-fuel.
FAR more efficient than terrestrial farming of corn.

May sound crazy at first read, but I think it will be real.

 

[Crabby]

Think it is bad now.
It is highly probably there is another big threat coming.
Farming of seaweed and kelp for bio-fuel!

There have been some breakthroughs recently in bacteria breaking down seaweed.
So the concept is simple. You set up some semi-floating substrate, over
a few square miles out at sea. Then pump semi-treated sewage from a city out to it. Mega-nitrates.
Maybe add a bit of special minerals and phosphates.
Then harvest and turn into bio-fuel.
FAR more efficient than terrestrial farming of corn.

May sound crazy at first read, but I think it will be real.

Algal biofuels ARE the next big thing. Because of the fact that little critters tend to have higher metabolic rates than bigger critters, plus the fact that they lose less energy in the maintenance of a complex multi-organ/tissue/cellular organism, gram-for-gram unicellular algae are much efficient at fixing carbon out of the atmosphere and converting it into biomass than bigger plants (corn, switchgrass). Lots of companies are trying to figure out ways to turn the ocean into thick green phytoplankton sludge, harvest that, and turn the carbon into something we can burn, like ethanol or butanol (a compound that is physically much more like gasoline from what I understand). An active area of research is engineering microorganisms that have unique combinations of metabolic pathways to break down the cellulose and other carbon-rich biomass in the plankton and convert that into a usable fuel.

If we use locally-produced human waste to fertilize the phytoplankton, we certainly will save on the carbon footprint involved in making and transporting fertilizer. If we can do this in a way that doesn't harm the reef, all the better.