Evidence of endocrine disruption of common carp at Willow Beach: Do we have an answer?

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Lake Mead Studies 1995-2000: An Assessment of Reproductive Function and Potential Endocrine Disruption in Fish

Evidence of endocrine disruption of common carp at Willow Beach: Do we have an answer?

Michael R. Rosen1, Reynaldo Patio2, David Alvarez3, Steven Goodbred4, and Kathy Echols3U.S. Geological Survey, 1Water Science Field Team, NV; 2 Texas Cooperative Fish & Wildlife Research Unit; 3Columbia Environmental Research Center; 4Emeritus, North Carolina

Why are we concerned with Willow Beach?One female Common Carp taken in 2003 showed signs of intersex with spermatozoa visible in ovarian tissue and poor development of testicular tissues in male carp (Hinck et al., 2006; 2007)

In 2007/2008 Additional sampling at Willow Beach confirmed intersex in female fish and 3 of 5 male fish had possibly malignant testicular tumors (seminoma)


SeminomaTestes from Willow Beach male carpFish Tissue and sediment samples collected in 2005 suggested organic chemicals (PCBs) may be an issue

Fish Tissue 2007 - 2008mean concentration (n = 6 20 fish per site)

Summary of field-based studies on Common Carp

The reproductive and endocrine condition of male carp in LMNRA differed among sampling sites and can be classified from higher to lower as follows:

OA > LVB > LBW > WB.

Especially notable were The weak seasonality in the reproductive physiology of male fish from LVW and WB;

The poor condition of fish from WB including the incidence of gonadal tumors and other reproductive organ anomalies.

Endocrine Disruption in Lake Mead5What is the reason(s) for these endocrine issues in carp from Willow BeachSeveral possibilities exist:

Effluent from wastewater plant at Hoover DamEffluent from wastewater from the Fish HatcheryPCBs from leaking transformers at the DamContaminants transported down from Lake MeadEnvironmental factors such as cold water released from Hoover Dam, low food or nutrient supplies, erosion of naturally occurring toxic minerals into the lake Old population of carpCurrent studyIn order to assess some of these possible sources:

Sediment, attached algae, and water (SPMD/POCIS) were collected at sites above and below the Fish Hatchery (5 sites total)Fish were collected for histopathology all around these sitesFood, caulk, and rubber were sampled at the Fish Hatchery.

Sampling sites along Willow Beach

Total distance is about 5 miles from site 1 to site 5

Google Earth Image2 milesFish HatcheryHoover DamLake Mohave


Fish Hatchery materials and feed

Algae and sediment

SPMD/POCIS SamplesNo PCBs found in water samples (not surprising)Concentrations of DDT metabolites, PAHs hexachlorobenzene (HCB), heptachlor, heptachlor epoxide, dieldrin, PBDE-47 and -99, triclosan and methyl triclosan are all higher than at Overton Arm, but not as high as Las Vegas BayOther chemicals are present however, but at low concentrations: no greater than Overton Arm: However.

Examples of other constituents in the water at Willow Beach

Water Temperature and Seasonality Temperature of Hoover Dam outlet water is generally cold: 52 55 oF (11 13 oC)Temperature doesnt change much seasonallyCarp spawn from May to June at 64 86F (18 30C) with optimum of 73F (23C)Therefore, cold temperatures and lack of seasonality may contribute to poor fish healthSeasonality in FishWithin a site, columns with same letter are not differentAsterisk - different from corresponding date in reference site (OA)Highlights:

E2/KT levels generally lower in OA than other sites, except WB.

Seasonality absent in LVW and WB.

E2/KT RatioFish Histopathology 2010

GSI (%)Testes MA area (%)Intestitia Thickness (mm)ConclusionsThere isnt any smoking gunFish Hatchery materials appear to have some PCBs in them and perhaps had more in the pastEstrogenic chemicals were detected in the water near the HatcheryPCBs and other contaminants occur at low concentrations upstream of the HatcheryLow temperature of the water and lack of seasonality cant be discounted as a contributing factorThanks to NPS and FWS for access to sites on Lake Mohave and the Fish Hatchery

Funding was from the USGS-NPS collaborative Water Quality Partnership Program