[Pharmwaste] FW: Laboratory Study Shows Future Generations of Fish Affected by Endocrine Disruptor Exposure

Volkman, Jennifer (MPCA) jennifer.volkman at state.mn.us
Thu Mar 26 17:43:48 EDT 2015


Does anyone else wonder why we still have fish? It seems like populations should have already started to dip below the numbers needed to maintain a reproductive population for several species in several lakes and streams due to decades of EE2 exposure alone. I've decided to sort through the private parts of all of the fish I catch this year to see what’s going on around here. I don't have a whole lot of experience determining the gender of fish, aside from saving eggs from sunfish for  Grandma Quiram who loved fried fish eggs...So, I did a search. And what the hey!!! This is from some aquarium digest about breeding fish. I think we can just raise or lower the temperature of an entire lake to get the gender we want. Interesting stuff if you are bored:

Influencing Gender in Developing Fish
 
Ichthyologists have long known that among some species of fish “gender” is a slippery concept. In some fish, gender can be altered by surgical and/or social changes during adulthood. This is possible since research has revealed that the gene cells of fish retain their bipotentiality to differentiate into male or female until full sexual maturation and beyond. A number of reef fish, and some freshwater species as well, may actually change sex several times during their lifetime. Labroides dimidiatus, the saltwater cleaner fish, lives in harems of females attended by a single male. When the male dies, a female from the group actually changes sex and takes over the male role, not only behaving like a male, but actually fertilizing the eggs of the other females.
 
Research also seems to indicate that the sex of developing eggs and fry may be directly affected by a variety of factors. Depending on the species, these may include the age of the spawning adults; the temperature, pH, and DH of the water; light levels; and the subtle mix of chemicals, hormones, and hormone-like substances in the water. This may help to explain why some aquarists have problems with severely skewed sex ratios in spawns from a certain species, while other aquarists working with the same fish have no problems at all, or find that the sex ratios are skewed the opposite way. This may occur because no two aquarists have exactly identical water conditions.
 
Gender Manipulation

Hobbyist breeders may encounter spawns that are heavily skewed toward one sex or the other. Commercial producers of food fish often prefer the predominance of one sex.
 
Commercial fish breeders, who spawn and raise fish in vast numbers for human consumption, have learned how to manipulate some of these developmental variables to their benefit, reducing aggression and markedly improving growth rates. Such gender manipulation may be achieved by chromosomal manipulation during fertilization and the embryonic stages, control of hormone levels during and just after hatching, and by temperature during the juvenile phases. However, research with a number of species has shown that outside (human) manipulation of gender in developing eggs and fry is only possible during very specific, limited time periods.
 
Chromosomal manipulation is limited to the few seconds and minutes during and immediately after fertilization of the egg and during its very early cleavages. Manipulation at this point can produce a hatch of all females, all males, or completely sterile individuals.
 
Hormonal manipulation is restricted to a few minutes just before or after hatching (using the immersion tech­nique) or to a few days after hatching for ornamental fish. In food fishes (such as carp and salmon) this may be ex­tended to a few months, when using dietary administration of hor­mones.
 
Thermal manipulation may be the simplest method for gender control in fish. Although only limited research has been conducted in this area, results seem to show that the technique works best with juvenile fish, and that lower tem­per­a­tures result in females and higher tem­pera­tures result in males. Actual sex determination is triggered by thermal con­trol of certain enzymes.
 
In large-scale aquaculture, manipulation for gender has been practiced for some time, using hormone and/or temperature treatments to produce all-one-sex spawns that grow better and produce more high-quality harvestable biomass at lower costs. Among tilapia, males grow more quickly than females, so single sex populations are highly desirable. These can be produced by manually sorting the fry for sex, by administering hormones to all the fry (male and female) during key growth periods, or by crossing different species.
 
Hormone treatment has also been used in the aquarium trade to produce all male spawns, and pressure treatments have been effectively used to produce sterile populations of desirable decorative species.
 
Although sex manipulation in developing eggs and fry has been widely practiced in many commercially important species for some time, there is evidence that over the long run it may result in stunted growth, sterility, and other undesirable secondary effects. It should also be noted that no one species has been thoroughly stu­died us­ing all the potential methods of gender manip­ulation.
 
Sex Ratio and Environment
 
Experiments with the Atlantic silverside Menidia menidia proved that the sex ratio could be influenced by environment, and that the sex determination of the fry was controlled by both the genotype and temperature during a specific stage of larval development. Surprisingly, spawn from different females varied in their responsiveness to changing temperatures. In general, the combination of lower temperatures and higher pH seemed to produce high numbers of females.
 
Keeping fry of various Apistogramma species at higher temperatures, especially during the first months, has resulted in the production of more males, and higher pH values produced more females. Best results, at least in one study, indicated that the most even sex ratio distributions for the study species occurred when water temperatures were maintained at about 78°F (26°C), with pH levels about 6.8 for the first month.
 
Among killifish, the Cynolebias species may react in a similar manner, although to fish from narrower temperature ranges, such as the rainforest Aphyosemion, pH may matter more. Aquarists working with killifish have observed direct links between water parameters and sex ratios. Among some of the Aphyosemion species, soft water (pH 6.5, 30 ppm hardness) at 72° to 76°F (22 to 24°C) resulted in 90 percent females. Harder water (pH 7.4, DH 140) at the same temperature produced mostly males. Cooler, moderately hard water resulted in roughly even sex distribution. Other aquarists have noted that reducing water hardness by adding reverse osmosis or rainwater produced more females.
 
Considerable anecdotal evidence also indicates that a number of variables may have an effect on sex differentiation. One noted breeder observed that if he raised a large group of Nothobranchius fry under crowded conditions, he invariably got larger numbers of males. Smaller batches of fry raised under less-cramped conditions usually (but not always) produced more even numbers of males and females.

______________________________________________
From: pharmwaste-bounces at lists.dep.state.fl.us<mailto:pharmwaste-bounces at lists.dep.state.fl.us> [mailto:pharmwaste-bounces at lists.dep.state.fl.us] On Behalf Of DeBiasi, Deborah (DEQ)
Sent: Wednesday, March 25, 2015 10:23 AM
To: pharmwaste at lists.dep.state.fl.us<mailto:pharmwaste at lists.dep.state.fl.us>
Subject: [Pharmwaste] Laboratory Study Shows Future Generations of Fish Affected by Endocrine Disruptor Exposure


Laboratory Study Shows Future Generations of Fish Affected by Endocrine Disruptor Exposure<http://feedproxy.google.com/~r/usgs/EnvironmentalHealth/~3/ltohAvywIhQ/article.asp?utm_source=feedburner&utm_medium=email>

Posted: 24 Mar 2015 08:00 AM PDT
Summary: Fish exposed to the endocrine-disrupting chemicals bisphenol A (BPA) or 17a-ethinylestradiol (EE2) in a laboratory have been found to pass adverse reproductive effects onto their offspring up to three generations later, according to a new study by the U.S. Geological Survey and the University of Missouri ________________________________

Contact Information:

Jennifer LaVista<mailto:jlavista at usgs.gov> ( Phone: 303-202-4764 ); Donald Tillitt <mailto:dtillitt at usgs.gov> ( Phone: 573-876-1866 );

________________________________


Fish exposed to the endocrine-disrupting chemicals bisphenol A (BPA) or 17a-ethinylestradiol (EE2) in a laboratory have been found to pass adverse reproductive effects onto their offspring up to three generations later, according to a new study by the U.S. Geological Survey and the University of Missouri.

Aquatic environments are the ultimate reservoirs for many contaminants, including chemicals that mimic the functions of natural hormones. Fish and other aquatic organisms often have the greatest exposures to such chemicals during critical periods in development or even entire life cycles.

Scientists exposed fish to either BPA or EE2 for one week during embryonic development, while subsequent generations were never exposed. Future generations showed a reduced rate of fertilization and increased embryo mortality. The full study, published in the journal Scientific Reports, is available online.<http://www.nature.com/srep/2015/150320/srep09303/full/srep09303.html>

“This study shows that even though endocrine disruptors may not affect the life of the exposed fish, it may negatively affect future generations,” said USGS visiting scientist and University of Missouri Assistant Research Professor, Ramji Bhandari. “This is the first step in understanding how endocrine disruptors affect future generations, and more studies are needed to determine what happens in the natural environment.”

There were no apparent reproductive abnormalities in the first two generations of fish, except for two instances of male to female sex reversal in adults of the EE2 exposed generation. Findings show a 30 percent decrease in the fertilization rate of fish two generations after exposure, and a 20 percent reduction after three generations. If those trends continued, the potential for declines in overall population numbers might be expected in future generations. These adverse outcomes, if shown in natural populations, could have negative impacts on fish inhabiting contaminated aquatic environments.

This study examined concentrations of EE2 and BPA that are not expected to be found in most environmental situations. However, concerns remain about the possibility of passing on adverse reproductive effects to future generations at lower levels. At this time, the ability to evaluate mixtures of estrogenic chemicals working jointly is limited.

The scientists studied BPA and EE2 because they are chemicals of environmental concern and represent different classes of endocrine disrupters. BPA is a chemical used primarily to manufacture polycarbonate plastics and epoxy resins, but is also an additive in other consumer products. Due to extensive use of these products in daily human life, the accumulation of BPA-containing waste in the environment has been a serious concern and a potential threat to public and wildlife health. EE2 is used in oral contraceptives designed for women, and about 16 – 68 percent of each dose is excreted from the body. As a result, EE2 has been found in aquatic environments downstream of wastewater treatment plants.

For more information on endocrine disruptors visit the USGS Columbia Environmental Research Center web page<http://www.cerc.usgs.gov/ScienceTopics.aspx?ScienceTopicId=6>.





Deborah L. DeBiasi
Email:   Deborah.DeBiasi at deq.virginia.gov<mailto:Deborah.DeBiasi at deq.virginia.gov>
WEB site address:  www.deq.virginia.gov<http://www.deq.virginia.gov/>
Virginia Department of Environmental Quality Office of Water Permits Industrial Pretreatment/Whole Effluent Toxicity (WET) Program PPCPs, EDCs, and Microconstituents http://www.deq.virginia.gov/Programs/Water/PermittingCompliance/PollutionDischargeElimination/Microconstituents.aspx
Mail:          P.O. Box 1105, Richmond, VA  23218
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028      FAX:      804-698-4032



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