Heavy phytoplankton bloom in Belize

[Hank49]

I've been diving here for 11 years now from San Pedro down to Placencia and I've never seen anything like this.
We have green algae (I haven't looked at it under a microscope yet) in our water inside the reef from Dangriga (haven't checked farther north) down to Placencia.
The secchi disk reading is around 30-40 cm. And it's like this almost all the way out to the reef. It thins out as you get within a few miles but it's still dirty and as the tide drops, the visibility outside the reef gets pretty bad.
Where are all the nutrients supporting this bloom coming from? It's been this way for over a month now. Somedays, the water coming in our pipeline from 450 yards out stinks like a conch shell.
I'm a little worried we might get the same thing that happened in California a few months back. If all this algae crashes, maybe the oxygen will drop and kill a lot of fish.
The diving outside is still good. The vis can get kind of bad but no worse than I've seen over the years. Its INSIDE the reef that's bad.

 

[Hank49]

It's been over 2 months now...almost 4 I think. The green bloom is still here.
Some updates. I looked at it under our hatchery scope. I'm not a phycologist but it was green, about 1 micron or smaller and had over 650,000 cells per milliliter. It was about the size of nanochloropsis sp but didn't "roll" around under the scope.
It's been reported by an environmentalist here that this is a problem from the Rio Dulce, south of here, all the way up around the Yucatan to Merida, Mexico.
I talked to a dive shop owner in Placencia and she said visibiity at Laughingbird Marine Reseve is really bad. She was doing training dives to 100 feet and said the vis was about 4 feet.
The winds have been strange this year. Southeast more than northeast and it's been really hot.
I'm a bit worried that we may have a crash and a big fish kill like they had in California earlier this year.
The incoming water on our shrimp farm looks like the water we discharge.
Fortunately, the open seawater still is clear.
Any ideas from you PhD oceanographers? Bill? Archman? Uncle Ned?

 

[archman]

Wow... you measured the cell diameter and performed density counts. That's hot. Most people just stop at "there's this green crud in the water and it smells".

As for what's causing it, the most typical culprit is nitrogen or phosphorous loading. The little unicellular algaes can respond to even slight nutrient upticks remarkably well. Is your reef fairly sheltered this time of year from winds, waves, current, etc.? Perhaps the 1970's save-all "The Solution to Pollution is Dilution" is getting messed up this summer in your area, and the outfall pipe effluent is sticking around more than it should. If your winds are piling up *into* the reef, that would also keep the little nasty microbes around. I recommend a nice? Tropical Storm, eek.

 

[Hank49]

Some people claim its chlorella but it doesn't look like it to me. Chorella is about 5 microns? This is like....1 micron or less. Tiny cells. And almost a mono culture.
And, off Placencia at Laughingbird Caye Marine Reserve, divers say they go down 100 feet and the vis is only 5 feet, and very dark. If it was chlorella I would think it would need more light and maybe be just nearer the surface? Perhaps it's some type of bluegreen? I've been looking for pictures on the internet but can't find an identical cell to what I saw here.
And today a good friend of mine just came back from Glovers Reef. You have to cross the barrier reef and go about 15 miles across blue, deep water to get there. He said the vis was terrible. Less than 10 feet. He didn't notice whether the water between the reef and Glovers was green also. I'll go out tomorrow and try to go to Turneffe, more north.
Weird. I can't imagine where that much nitrogen would come from. Blues greens can fix it but even the phosphorus and potassium....??? Could it be related to the big oil spill in the Gulf of Mexico last year?

 

[archman]

Blue-green's are teeny, so maybe. My awesome phytoplankton book is packed in a box... somewhere.

You got a low-range phosphorous test kit at the hatchery? My bet's on that.

 

[Hank49]

No, I don't. How could we end up with such a massive does of phosphorous? Agricultural runoff? From where? Very strange.
I have a friend in Puerto Rico who says they had this happen last year. The green plankton was 20 miles offshore. And then they had a lot of fish after that.
The hook and line fishermen here say they're doing great. It's really bad for diving though.
I didn't get to Turneffe yesterday. Too rough so I"m going in about 10 minutes.
This really sucks though. It's going to affect Belize tourism is the diving doesn't improve.

 

[archman]

Tropical waters are normally so nutrient-poor, the plankton are super-evolved to take advantage of even the most miniscule upticks of limiting nutrients. And generally, the teenier the plankton-size class, the more efficient the nutrient uptake is. So basically, it hardly takes anything to promote phytoplankton blooms. All a locale really needs is a nutrient input a *hair* above ambient levels typically, and for the water mass to be locally entrained for a few weeks or longer. Hence performing nutrient examinations that are calibrated to pick up *very low* levels.

Hopefully your area will clear up when your winds shift to the way they normally go, or when a nice storm blows through. You don't have any cruise ships that come around your area, do you? Or have any new coastal construction or housing projects?

 

[Hank49]

Cruise ships are coming less frequently I hear. No big construction. Just a very hot year so far.
I 've been hearing that this is stretching from the Rio Dulce, Guatemala, south of us, all the way up to Cancun and around the corner of the Yucatan to Merida, Mexico.
I went out north of here and east to day and the water outside the reef is getting a bit green too. Not nearly as dense as from 8 miles into the mainland.
The low nutrient level makes sense. But this has been here for three months now. And the algae density is very high even 80 - 100 feet deep down off Placencia.
A spearfisherman I know in Puerto Rico said they had dense green algae extending as much as 20 miles offshore last year. It went away and a huge jump in fish populations followed. I hope it happens here.

 

[Hank49]

Invest 93 : Computer Model Hurricane Forecasts : Weather Underground

Arch, you might get our wish with this one. Personally, I'd rather put up the green water for a while longer. I hate these things.
The water outside the reef due east of Mullins river has a greenish tint. Vis was only about 30 feet yesterday. I didn't get to Turneffe. Too rough in the morning.