Pollution & its effects on native species article

Just read this, thought I'd share.

http://www.scienceda...20711074232.htm

This article is interesting as it reminds me of a conversation I had with a famous swordtail breeder from Asia about 8 years ago. The breeder mentioned that the plastic buckets they used to raise the fry could be one of the factors that potentially leads the fish to become a male or female.

The conclusions might or might not be real, but this article is a total piece of crap IMO. I see a couple sentences about experimental set-up, and then some generic conclusions about effects of BPA, not necessarily about fish. NO mention at all of the experiment's results. The fish were collected in GA where blacktail is native and red is exotic, so they may not have had strong behavioral isolating mechanisms to begin with. Introduced reds will hybridize with many other Cyprinellas. Ms. Ward should have done this with native sympatric populations. And what about tank size? Aggressive male reds may simply have prevented blacktail males from defending spawning sites if the tank was too small, leaving blacktail females no choice about who to spawn with. Endocrine disruptors may be serious problems, but weak articles like this are just fuel for the deniers.

http://www.scienceda...20711074232.htm

Hormone-Mimicking Chemicals Cause Inter-Species Mating: Bisphenol A Breaks Down Fish Species Barriers


ScienceDaily (July 11, 2012) — Hormone-mimicking chemicals released into rivers have been found to impact the mating choices of fish, a new study has revealed. The controversial chemical BPA, which emits estrogen-like properties, was found to alter an individual's appearance and behavior, leading to inter-species breeding. The study, published in Evolutionary Applications, reveals the threat to biodiversity when the boundaries between species are blurred.

The research, led by Dr Jessica Ward from the University of Minnesota, focused on the impact of Bisphenol A (BPA) on Blacktail Shiner (Cyprinella venusta) and Red Shiner (Cyprinella lutrensis) fish which are found in rivers across the United States. BPA is an organic compound used in the manufacture of polycarbonate and other plastics. It is currently banned from baby bottles and children's cups in 11 U.S. states.

"Chemicals from household products and pharmaceuticals frequently end up in rivers and BPA is known to be present in aquatic ecosystems across the United States," said Ward. "Until now studies have primarily focused on the impact to individual fish, but our study demonstrates the impact of BPA on a population level."

The team collected individuals of both species from two streams in the state of Georgia. The species were kept separated for 14 days in tanks, some of which contained BPA. On the 15th day behavioral trials were undertaken as individuals from different tanks were introduced to each other.
The scientists monitored any physiological or signalling differences the individuals displayed, such as color, as well as any behavioral differences during courtship, such as mate choice.

BPA disrupts an individual's endocrine system, which controls the release of hormones. This impacts behavior and appearance, which in turn can lead an individual to mistake a newly introduced species as a potential mate. This process poses long-term ecological consequences, especially in areas threatened by the introduction of invasive species. BPA and other hormone-mimicking chemicals can escalate the loss of native biodiversity by breaking down species barriers and promoting the invader.

"Our research shows how the presence of these humanmade chemicals leads to a greater likelihood of hybridization between species," concluded Ward. "This can have severe ecological and evolutionary consequences, including the potential for the decline of our native species."