Let me see if I understand this correctly. Algal blooms can either be very good or very bad.
On the good side the nutrients are feeding algae that is important to the food chain in the ocean.
On the bad side, some types of algae release bad toxins.
Which happened in the blooms in Mexico?
I'm a bit skeptical about this report, because it seems to be leaving a lot of information out.
It talks about red tides and hypoxia, but it doesn't say that they saw evidence of those occurrences in the areas they were observing.
They mention problems with hypoxia at the end of Mississippi river, but they don't really show that they have any evidence to show that it's related to algal blooms or nutrient runoff. I suspect that there are a lot of different pollutants in the Mississippi river, what ties the hypoxia to the nutrients?
The article mentions bacteria that eats the algae uses up oxygen. However green algae is the biggest source of oxygen in the oceans. I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water. That kind of seems to violate the natural cycle.
""In the Sea of Cortez, there's the possibility that hypoxia could occur at a local scale, which could be devastating to the shrimp and shellfish industries," Matson said"
Sounds like another way of saying that we saw widespread evidence of algal blooms but no evidence of hypoxia, yet you should still be concerned because we say it could be happening.
""Shrimp fisheries are very important economically, and they're already under a lot of stress from overfishing and aquaculture. It is possible that agricultural runoff could cause additional stress if it does lead to toxic blooms or hypoxia." She and her colleagues plan to conduct follow-up studies to assess the ecological impact of Yaqui Valley runoff events."
Shrimp eat algae. So unless the runoff is causing toxic blooms, I would think that the shrimp population would thrive during algal blooms. If the shrimp populations are low, it sounds like there might be other causes.
It sounds like they gathered some good information with their research. However the tone of the article seems to imply that these algal blooms are bad. All they've done so far is show that the nutrients appear to effect algae growth, but they don't know what type of algae or if it's good or bad.
They appear to be concentrating on possible harm. It always scares me when environmentalists go into research and appear to already assume that there is harm being caused, and then look for evidence that they are right.
I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water. Its more of an indirect effect. Untreated wastewater is generally rich in organic matter. This organic matter feeds the bacteria and algae normally present in healthy water sources. The presence of excessive amounts of nutrients discharged as a result of untreated wastewater will cause an increase in concentration of both bacteria and algae within the surface water. Beside organic matter, wastewater also contains both organic and oxidizable inorganic compounds. These organic and inorganic compounds directly and indirectly consume the available oxygen present in the ecosystem. This process is called eutrification and will eventually kill off other living organisms (plants, animals, & insects) in the aquatic system.
You wrote a lot. In general, the issue with normal, non-toxic algal blooms is like a lot of other things; when they're normal, they aren't a problem. When there's too much, that can cause problems (likewise with too little).
It talks about red tides and hypoxia, but it doesn't say that they saw evidence of those occurrences in the areas they were observing.
They didn't; but the study supports the linkage between agricultural runoff and blooms that induce hypoxia elsewhere.
They mention problems with hypoxia at the end of Mississippi river, but they don't really show that they have any evidence to show that it's related to algal blooms or nutrient runoff. I suspect that there are a lot of different pollutants in the Mississippi river, what ties the hypoxia to the nutrients?
Pollutants that don't enhance phytoplankton growth don't participate in the process that causes hypoxia; they're just pollutants. Excess nutrients like nitrogen and phosphorus do enhance phytoplankton growth.
The article mentions bacteria that eats the algae uses up oxygen. However green algae is the biggest source of oxygen in the oceans. I'm having a hard time buying the argument that more green algae results in a net loss of oxygen levels in the water.
Hypoxia is a problem on the sea floor. The algae die and sink to the bottom and get consumed by the bacteria. That's where the oxygen depletion occurs, not at the surface where the algae are growing.
Shrimp eat algae. So unless the runoff is causing toxic blooms, I would think that the shrimp population would thrive during algal blooms.
Shrimp breathe (respire), too, and they inhabit the bottom of the water body. If they are in waters that become hypoxic, they have to leave.
It sounds like they gathered some good information with their research. However the tone of the article seems to imply that these algal blooms are bad. All they've done so far is show that the nutrients appear to effect algae growth, but they don't know what type of algae or if it's good or bad.
I think it's more appropriate to say that excess algal blooms can be (but aren't always) bad. They don't really say that they've seen detrimental effects from this process in the Sea of Cortez, leading me to think that they haven't.