Officials in Maryland have used the presence of lesions on fish as a reason for closing coastal waterways to fishing and all other water activities. They thought that the lesions on the dead fish were caused by a type of microscopic algae known as Pfiesteria. The toxins produced by Pfiesteria are believed to cause headaches, fatigue, and short-term memory loss in humans who come into contact with contaminated waterways.

A new study suggests that lesions on fish may not always be caused by Pfiesteria. A team of U.S. Geological Survey scientists led by Vicki Blazer, a specialist in fish diseases, examined menhaden, a type of fish, from five Chesapeake Bay rivers where fish lesion outbreaks had been reported. The researchers found that when the fish had lesions, they were almost always the type that are associated with infection by a fungus called Aphanomyces.

Researchers now hypothesize that Pfiesteria may infect fish first, leaving them more susceptible to infection by Aphanomyces. The fish then break out in lesions. An alternative explanation is that Aphanomyces infects the fish first, causing lesions and leaving them more susceptible to infection by Pfiesteria.

The question of whether outbreaks of fish lesions are a useful indicator of the presence of Pfiesteria has erupted into a full-blown controversy. Blazer's study has suggested that lesions are not a reliable indicator. Blazer has stated that anxiety about Pfiesteria has "overstepped the bounds of reality," and she expressed concern about the economic cost of closing waterways.

JoAnn Burkholder, the biologist who discovered Pfiesteria, strongly disagrees with Blazer's point of view. "To abandon the lesion approach is to take some very serious chances with people's health." According to Burkholder, this approach is "an extra precaution" that allows officials to go "the extra mile" in protecting human health.

1. Which of these human problems is caused by toxins in the microscopic algae known as Pfiesteria.

O   a. lesions
O   b. short-term momory loss
O   c. infections
O   d. low blood pressure

2. One scientist believes lesions in fish are caused by infection with the fungus

O   a. Pfiesteria
O   b. Aphanomyces
O   c. Streptococcus
O   d. none of these

3. The coastal waterways were closed to fishing and all other water activities by

O   a. Vicki Blazer
O   b. JoAnn Burkholder
O   c. Officials in Maryland
O   d. none of these

4. The closing of the coastal waterways is opposed by

O   a. Vicki Blazer
O   b. JoAnn Burkholder
O   c. Officials in Maryland
O   d. none of these

5. Which data table is best represented by the graph below? O   a. Data Table #1 O   b. Data Table #2 O   c. Data Table #3 O   d. Data Table #4

6. Four teams of students independently tested the effects of temperature on the gill movements of goldfish. The results from their tests are shown in the data tables. The results of Team 3 were questioned by the other teams. Which of these should the students on Team 3 do to validate their results? O   a. Use data from one of the other teams for the counts taken at 15 oC. O   b. Repeat the experiment at 15 oC using the same set of goldfish. O   c. Use containers made of different materials to test the goldfish again. O   d. Repeat the experiment at 15 oC using larger goldfish.