When Water Becomes Toxic

 Public Service Announcement.

The fun of living in an agricultural-dominated state: Toxic algae season has begun. Water sampling in my local area, Nebraska, began last week.

I have blogged about similar things, but the problem is getting so bad that a revisit is warranted. This problem is lowering the quality of life for millions, killing fish, pets, and people, and will soon be killing humans at an alarming rate.

Most harmful algae blooms in Nebraska are caused by blue-green algae/cyanobacteria, which produce toxins. The major toxins of concern are Microcystins.

Recommendations issued by the U.S. Environmental Protection Agency (EPA) trigger a health alert at 8 parts per billion of the toxin microcystin. Read that again: 8 parts per 1,000,000,000. Dangerous stuff. 

When a beach is under alert, it is recommended that no contact with the water occur.

Microcystins are potent liver toxins and human carcinogens. They can also kill livestock and pets that drink affected water. Fish and bird mortalities occur during blooms.

Let me segue way to Florida.

Though it’s not very scientific, headlines harken the dangers.

In Florida, at the end of 2023 and into 2024, fish, including the endangered sawfish, have been seen spinning in circles and eventually dying.

The likely culprits are toxins from algae, from the microscopic dinoflagellates. Florida, with its string of anti-environment Governors, has relaxed regulations, which in Florida were not strong enough anyway, leading to water quality issues. For example, Florida regularly has toxic algae blooms that last months. 

The toxin-producing dinoflagellate Gambierdiscus was found in high concentrations in some places and might be the species involved. However, several toxic or potentially toxic algae species occur in high numbers, so a mix of toxins is likely responsible. Species in this genus can cause ciguatera poisoning, not a time to eat fish.

The Sawfish of concern is the Smalltooth Sawfish, Pristis pectinata. The number of individuals left in the Florida area is unknown, but it is in the low hundreds. AND at least 47 have died due to this latest problem. An attempt at rescuing an 11-foot sawfish by the Mote Marine Lab was unsuccessful: They put the animal in clean water and gave it antibiotics and other potential treatments. It’s very sad, but just the tip of the iceberg. These toxins are coming for us. We are not immune. 

 Smalltooth Sawfish are amazing animals. The massive saw/rostrum can be 1/4 the length of the shark. The rostrum has thousands of pores leading to electroreception organs called Ampullae of Lorenzini. This allows the shark to hone in on prey, sensing the muscle activity. They mostly eat fish and sometimes use their rostrum, which is spiked, to slash through a school of fish. The shark then turns around and sucks up the dead or dying fish (fish pieces). 

Though these sharks are rare, and there is much more to learn about them, we know that they give birth to live young, up to 20 pups, and may hold the developing young for nearly two years. Such a long period means the population recovery will take a long time. First, we have to stop killing them with the chemicals we spread in the fields.

Figure 1. Smalltooth Sawfish in an aquarium. Smithsonian Institution.

Pesticides and Herbicides:

Beyond the excess nutrients that cause toxic plankton blooms, a bevy of toxins are directly sprayed onto farm fields. Herbicides and pesticides run into rivers and seep into groundwater, tainting lakes, oceans, and drinking water systems. Total pesticide use in agriculture has increased by 11 percent in a decade and has doubled since 1990. In 2021, usage amounts were 3.5 million metric tons. The Americas account for the largest amount of pesticide use. 

Figure 2. Agricultural consumption of herbicide use worldwide: 1990 to 2021.

By 2021, herbicide use worldwide was 1.4 metric tons. The graph of increasing use of pesticides looks very similar to that above for herbicides. WTF is going on. 

Meat processes that directly dump toxins into waterways, like that done by Tyson Foods, exacerbate the already bad problem.

https://www.theguardian.com/environment/2024/apr/30/tyson-foods-toxic-pollutants-lakes-rivers

I’m not a big fan of regulations, but we need more industry regulations. 

And don’t think you folks who use Roundup to kill the plants growing out of the sidewalk cracks are completely off the hook. The amount is small compared to agriculture, but seriously, this stuff is nasty; stop it.

Ultimately, just like in Nebraska, the cause of the die-offs in Florida is not the algae but the agricultural runoff that causes massive blooms. This problem occurs in many other places as well. We must stop dumping so much on our crops; it’s killing us.