OK, first of all, forgive me if this has been asked before, but I couldn’t come up with any search keywords that didn’t return a million results…
Anyway, we’ve all seen the commercials from the Caribbean Tourist Board (or whoever puts them out) bragging about how clear their ocean water is. I live in the northeast, and our water is anything but clear. But that’s not to imply that it’s not clean; it’s my understanding that the water’s greenish tinge is due to algae, not polution. If that’s the case, why is the Caribbean water so clear? Don’t they have algae in the tropics?
There are pollutants that don’t distort water and there are natural causes that do. I dive the LI, NY waters and have come to this conculsion. The waters here suck (have low visability) because of the gulf stream that carries all pol.utants dumped from flordia all the way to NYC (along w/ all the rivers that flow into here) right here. Combine that with all the boat traffic and shallow waters on the south shore of LI (boat prop stirring it up) and a algee bloom an you can’t see $#!+ infront of you mask.
so back to your OP,yes is’t more poluted but that’s not the only reason for bad vis. The caribian gets it’s water from across the atlantic with no factories to dump anything there.
Oxygen content. Gases are less soluble in warm water.
Which is why, contrary to expectations, all the big fisheries, algae, and sea life is up in the colder areas and the tropics are (relatively) unpopulated.
It’s difficult to say whether water is polluted or not just by looking at it, that’s why there are hundreds of different water quality tests that often require lab equipment that costs a fortune (and takes a degree to run) to detect what’s in the water or not. Off BC where I am, water clarity varies with the season. Visibility (and diving) are best in the winter when there’s not enough sunlight and warmth to grow algae… there are the same amounts of nutrients pretty much year round though.
The reason that tropical waters where coral grows are so clear is that most of the algae production takes place within the coral it’s self by the symbiotic algae that grow within the heads, instead of vast clouds of phytoplankton growing in open water. The coral algae takes up many nutrients for their own growth which makes it hard for free floating algae to grow in huge numbers and “cloud” the water. Another thing to keep in mind is that water can be crystal clear and still be polluted; in my area there are many clam beaches that are closed due to the high faecal coliform counts (sewage pollution), while the waters remain very clean “looking”
To address a point made a few posts back, there is significant fish production in tropical waters (just watch a nature show), but there are so many different species (often smaller ones) that commercial fishing for a single target species is difficult and growing increasinly unpopular among conservationists who want to save the reefs.
The reason most big fisheries are in temperate areas is that there are more nutrients available; also there are fewer target species but greater numbers of them. These fisheries are often found in areas where upwelling of deep ocean water occurs. Lots of nutrients = lots of plankton growth = lots of big fish schooling in to eat it. It’s not a matter of low oxygen content, there are thousands of tropical fish evolved to live in lower O2 water. More a matter of lots of food and only a few types of big fish in the area to eat it (and get caught by us).
One thing I’ve learned from my career in environmental engineering is that most pollution is not visible. In fact, many polluted sites are in pristine, natural-looking areas because people usually sneak off into the woods to dump their chemicals/trash.
Anyway, back on topic, from what I have heard, I agree with the statement that the clarity of water in the Caribbean is due to the lack of nutrients as compared to the more nutrient rich waters up here in the northeast U.S.
Hooray for the critters in dark water, but the clear water sure looks better doesn’t it?