Читать книгу Fundamentals of Aquatic Veterinary Medicine - Группа авторов - Страница 56

There are many different classes of herbicides. Most herbicides do not directly affect fish; however, different species of fish respond to varied levels and classes of herbicides. Studies performed on forestry herbicides in regard to fish development showed no evidence of toxicity in zebra fish to picloram, clopyralid, imazapic, glyphosate, imazapyr, and triclopyr (Stehr et al., 2009). However, studies evaluating Cyprinus carpio and rohu showed an increased mortality and histologic changes in the kidney, liver, and gills when exposed to glyphosate at 86 mg/l. This same study showed increased mortality in response to the use of the salt formulation of 2, 4‐D at 100 mg/l and paraquat at 26 mg/l.

Atrazine has been shown to affect the hypothalamus–pituitary–gonadal axis in vertebrates. One study has shown that this herbicide negatively affects the egg production of fathead minnows (Tillitt, 2010).

Pretilachlor is frequently used in rice fields. Studies performed on Clarias batrachus exposed to this herbicide had significant behavioral changes, including decreased feeding and increased buccal activity (Soni, 2018).

At high levels, triazine has been shown to cause acute toxicity in fish. This herbicide can also cause negative affects regarding reproduction and reproductive development (Hostovsky et al., 2014).

When diagnosing possible toxic exposure in a fish population, herbicides should be considered if they have been used in the water or in the area nearby due to potential runoff. When developing a farm management program that includes herbicides, it is important to consider the following:

 The sensitivity of the species you are working with.

 The potential exposure to wild fish in the area and their sensitivity.

 The bioaccumulation of the herbicide directly into the water or in the runoff.

 The half‐life of the chemical if it is used in an unpopulated pond.