If you’ve spent any time herping near ponds, lakes, or slow-moving streams, you’ve probably seen it, water coated in a green, paint-like scum or streaks of red-brown film drifting across the surface. While some algae growth is natural and even beneficial, not all blooms are harmless. Certain species of algae, particularly cyanobacteria (commonly called blue-green algae), can produce dangerous toxins that threaten not just fish and birds, but also the reptiles and amphibians we encounter during our adventures. Understanding how these blooms impact herps is essential for both conservation and safe fieldwork.

What Are Harmful Algal Blooms (HABs)?
Harmful algal blooms occur when algae, often fueled by warm temperatures, excess nutrients from fertilizers, and stagnant water, grow out of control. In freshwater systems, cyanobacteria are the main culprits. They can release potent toxins such as microcystins, anatoxins, and saxitoxins. These compounds can be harmful or even lethal to wildlife, livestock, and humans. For reptiles and amphibians, which rely heavily on aquatic habitats for drinking, feeding, breeding, and thermoregulation, HABs present multiple threats.

How Amphibians Are Affected
Amphibians, with their highly permeable skin, are especially vulnerable to toxins in the water. When frogs, salamanders, or newts are exposed to cyanotoxins, the compounds can be absorbed directly through the skin and enter the bloodstream. This can lead to:

• Skin irritation and lesions that make the animals more susceptible to infections.
• Neurological effects, especially from anatoxins, which can disrupt muscle control and movement.
• Organ damage, particularly to the liver, from microcystins.

Egg development is also at risk. Amphibian eggs have delicate, jelly-like coatings that offer little protection against waterborne toxins. Exposure during critical early stages can lead to deformities, reduced hatching success, or even mass die-offs in breeding ponds.

How Reptiles Are Impacted
While reptiles have less permeable skin than amphibians, they’re not in the clear. Turtles, water snakes, and crocodilians often ingest contaminated water while drinking or feeding. Toxins can also build up in prey items, such as fish, invertebrates, or amphibians, that have been exposed to HABs. Over time, this bioaccumulation can cause:

• Liver and kidney damage from repeated toxin ingestion.
• Neurological issues that impair movement, hunting, or escape responses.
• Reduced reproductive success due to weakened overall health.

Aquatic reptiles like softshell turtles or garter snakes that hunt in shallow, algae-choked waters are particularly at risk. Even semi-aquatic species, such as some lizards, can be exposed when entering contaminated water for hydration or thermoregulation.

What This Means for Field Herping
For anyone passionate about field herping, toxic algae is more than just a nuisance, it’s a real hazard for both animals and people. Not only can it alter the biodiversity of a habitat by killing off sensitive species, but it can also make your own time in the field dangerous if you come into contact with contaminated water. Wading into an algae bloom without protection can lead to skin rashes, respiratory issues, or worse.
If you’re out herping and spot suspicious water (pea-soup green, streaked with surface scum, or emitting a foul odor), it’s best to:

• Avoid direct contact with the water and keep pets away.
• Document and report the bloom to local environmental agencies.
• Observe from a distance rather than entering the water for captures or photography.
• Decontaminate gear and boots before moving to a different site to avoid spreading algae.

Conservation and Prevention
The rise in HAB frequency is linked to climate change, nutrient pollution, and altered water flow. Conservationists are calling for better agricultural practices, stormwater management, and habitat restoration to reduce nutrient runoff and improve water quality. For herpers, supporting these efforts is one way to protect the ecosystems we love to explore.