Collapse of a fish population after exposure to a synthetic estrogen

1. 

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   Fig. 1.

   Mean ± SE (n = 4–7) VTG concentrations in whole-body homogenates of male (Lower) and female (Upper) fathead minnow captured in 1999–2003 from reference Lakes 114 and 442 and from Lake 260 before and during additions of 5–6 ng·L⁻¹ of EE2 (low catches of fish in Lake 260 in 2004 and 2005 did not allow for these analyses in the latter 2 years of the study).

   
   
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   Fig. 2.

   Gonadal tissue sections from fathead minnow sampled in early May 2003. (A) Ovary from reference Lake 442 with small, dark, primary-stage oocytes situated between cortical alveolar-stage oocytes and large vitellogenic oocytes. (B) Ovary from EE2-amended Lake 260 demonstrating an atretic follicle (arrow). (C) Testis from reference Lake 442. (D) Testis from EE2-amended Lake 260 demonstrating intersex; arrows indicate primary-stage oocytes among the remnants of testicular tissue. (Scale bars: A, B, 300 μm; C, D, 80 μm.)

   
   
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   Fig. 3.

   Length frequency distributions of fathead minnow captured in trap nets in reference Lake 442 (A) and Lake 260 (B) (amended with 5–6 ng·L⁻¹ of EE2 in 2001–2003) during the fall of 1999–2005. Distributions for each fall have been standardized to 100 trap-net days. Mean ± SE daily trap-net CPUE data for adults and juveniles for the fall catches are shown in the panels.