Pesticides are a great way to get rid of annoying pests around your plants if you are a farmer, but not if you are a fish. Pesticides greatly degrade ecosystem functions, the amount of wildlife, and even human health. Many animals that live in and around water are killed because of pesticides, many of these animals being already endangered, such as the Peregrine falcons. Many animals are forced to compete with one another and have to move farther away from their home because of pesticides killing off their food sources. Pesticides even affect reproductive success, as many aquatic animals use the plants in ponds, lakes, and rivers to hide and find food.
Pesticides are often highly involved in fish kills, many of which are underestimated, not reported because of "lack of importance", or unseen, as some fish may camouflage themselves to hide from predators in their dying moments. Pesticides that are often sprayed into the water kill many fish through suffocation, as the aquatic plants in the water bodies provide 80% of the dissolved oxygen necessary for aquatic wildlife. Killing off these plants can also lead to decreased animal productivity, decreased food supply, and decreased area for habitats. Other sub-lethal effects of pesticides include weight loss of fish, low disease resistance, sterility, reduced egg production, loss of attention, low predator avoidance, reduced adult survival, and lowered population abundance.
Aquatic animals are exposed to pesticides in three ways: through their skin, through their gills, or through their mouth. Secondary poisoning kills many fish as well, as the fish may ingest insects or plants that have been affected by pesticides. Humans can be affected by tertiary poisoning, as they may eat the fish that ate the insect or plant that had been affected by pesticides. The three main types of pesticides used are herbicides for weed control, insecticides for insect control, and fungicides for fungi. Other pesticides used are nematicides which are used for soil, leaf, or stem dwelling nematodes and acaricides for mites and ticks.
Pesticides are often highly involved in fish kills, many of which are underestimated, not reported because of "lack of importance", or unseen, as some fish may camouflage themselves to hide from predators in their dying moments. Pesticides that are often sprayed into the water kill many fish through suffocation, as the aquatic plants in the water bodies provide 80% of the dissolved oxygen necessary for aquatic wildlife. Killing off these plants can also lead to decreased animal productivity, decreased food supply, and decreased area for habitats. Other sub-lethal effects of pesticides include weight loss of fish, low disease resistance, sterility, reduced egg production, loss of attention, low predator avoidance, reduced adult survival, and lowered population abundance.
Aquatic animals are exposed to pesticides in three ways: through their skin, through their gills, or through their mouth. Secondary poisoning kills many fish as well, as the fish may ingest insects or plants that have been affected by pesticides. Humans can be affected by tertiary poisoning, as they may eat the fish that ate the insect or plant that had been affected by pesticides. The three main types of pesticides used are herbicides for weed control, insecticides for insect control, and fungicides for fungi. Other pesticides used are nematicides which are used for soil, leaf, or stem dwelling nematodes and acaricides for mites and ticks.
Herbicides
Herbicides are the most commonly used pesticide in the U.S. and are commonly applied directly to lakes, ponds, etc. to used to control algae, submerged water plants, emergent water plants, and floating water plants. Algae can interfere with swimming, boating, fishing, and can discolor the water while emitting a strong odor. These things cause people to get rid of algae in their ponds without thinking twice, a mistake many make.
Even though herbicides are generally less toxic than insecticides, only ten out of about 200 herbicides are labeled for aquatic wildlife. However, runoff from farms can majorly affect the bodies of water.
Herbicides for Aquatic Use
Endothall: Can be very toxic to wildlife at rates needed to kill weeds. It is the most common herbicides used are copper sulfate, fluridone, glyphosate, zx, and diquat.
Copper Sulfate (bluestone): Used to control algae, but is very toxic at rates needed to kill algae especially in soft water, because of copper, a long-lived metal. Toxicity increases as water hardness increases.
Fluridone (sonar): The safest herbicide to use, but is used for submerged water plants and is very slow-acting and long-lasting.
Glyphosate (rodeo): applied directly to the plant and is used for emergent water weeds, such as cattail, and has no activation period
2-4-D (Aquacide, Aqua-Cleer, etc.): Used for controlling submerged water plants and decomposes quickly, but is less effective at higher pH levels but more toxic at lower pH levels. Can be very toxic to Rainbow Trout with certain formulas.
Diquat: can be used for many things and dissolves very quickly- cannot be found after ten days.
Even though herbicides are generally less toxic than insecticides, only ten out of about 200 herbicides are labeled for aquatic wildlife. However, runoff from farms can majorly affect the bodies of water.
Herbicides for Aquatic Use
Endothall: Can be very toxic to wildlife at rates needed to kill weeds. It is the most common herbicides used are copper sulfate, fluridone, glyphosate, zx, and diquat.
Copper Sulfate (bluestone): Used to control algae, but is very toxic at rates needed to kill algae especially in soft water, because of copper, a long-lived metal. Toxicity increases as water hardness increases.
Fluridone (sonar): The safest herbicide to use, but is used for submerged water plants and is very slow-acting and long-lasting.
Glyphosate (rodeo): applied directly to the plant and is used for emergent water weeds, such as cattail, and has no activation period
2-4-D (Aquacide, Aqua-Cleer, etc.): Used for controlling submerged water plants and decomposes quickly, but is less effective at higher pH levels but more toxic at lower pH levels. Can be very toxic to Rainbow Trout with certain formulas.
Diquat: can be used for many things and dissolves very quickly- cannot be found after ten days.
Insecticides
In 1962, the most predominant insecticides were synthetic chemicals called organochlorine insecticides (OC's). Some toxic ones include aldrin, toxaphene, dieldrin, mirex, and heptachlor. Perhaps the most infamous one is DDT (dichlorodiphenyl-trichloroethane), which had devastating effects on aquatic wildlife. These OC's are now banned in the U.S., which was a very important factor in the survival of fish.
Nowadays, the four main types of agricultural insecticides are pyrethroids (PY's), organophosphates (OP's), carbamates (CB's), and biological insecticides (BI's). PY's, especially synthetic ones, are the most toxic ones. However, these are rarely absorbed by marine animals, as they are applied in small dosages and absorbed by mud. OP's and CB's are extremely hazardous and have been involved in fish kills, but can be water soluble. The CB insecticide carbofuran is extremely toxic. OP insecticides can bioconcentrate in fish, frogs, tadpoles, and toads to levels that can be hazardous to their predators. BI's can be less toxic because they target specific insects and include microbials and insect regulators. Microbials such as Bacillius thuringiensis (BT) cause the insects to be affected by a disease and does not affect wildlife. Insect growth regulators such as Diflubenzuron (Dimilin) inhibits the formation of an exoskeleton in insects, which kills them off. Even though BI's may be safer, they do limit food supply.
Nowadays, the four main types of agricultural insecticides are pyrethroids (PY's), organophosphates (OP's), carbamates (CB's), and biological insecticides (BI's). PY's, especially synthetic ones, are the most toxic ones. However, these are rarely absorbed by marine animals, as they are applied in small dosages and absorbed by mud. OP's and CB's are extremely hazardous and have been involved in fish kills, but can be water soluble. The CB insecticide carbofuran is extremely toxic. OP insecticides can bioconcentrate in fish, frogs, tadpoles, and toads to levels that can be hazardous to their predators. BI's can be less toxic because they target specific insects and include microbials and insect regulators. Microbials such as Bacillius thuringiensis (BT) cause the insects to be affected by a disease and does not affect wildlife. Insect growth regulators such as Diflubenzuron (Dimilin) inhibits the formation of an exoskeleton in insects, which kills them off. Even though BI's may be safer, they do limit food supply.
Fungicides
Fungicides are not as toxic as insecticides, but some have still been banned, such as those with mercury. They were banned in the U.S. in 1976 because the mercury would accumulate in the environment and in the food chains.