A marine reserve shows a coral reef that has recently been invaded by lionfish. Fig. 1 is a line-art view of a diver recording fish above the coral. Lionfis...
Question 1 Report
A marine reserve shows a coral reef that has recently been invaded by lionfish. Fig. 1 is a line-art view of a diver recording fish above the coral. Lionfish eat many small reef fish, including young parrotfish. Parrotfish feed on algae growing on coral surfaces.
Table 1 compares counts made at six reef sites inside the reserve. Each count covered 100 m2 of reef and was completed at the same water temperature.
| Site type | Mean lionfish count | Mean parrotfish count | Algae covering coral / % |
|---|---|---|---|
| Sites with lionfish removed | 1 | 34 | 12 |
| Sites with many lionfish | 12 | 9 | 47 |
(a) Describe the difference in parrotfish count between the two site types. [2]
(b) Use the information to suggest why algae cover is greater at sites with many lionfish. [2]
(c) Suggest one reason why the researchers counted fish at several sites. [2]
(d) Name one way divers could help control the invasive lionfish population. [2]
Answer Details
Labelled answer diagram:
(a) There were fewer parrotfish at sites with many lionfish: 9 compared with 34 at sites where lionfish were removed. This is a difference of \(34-9=25\) fish. [2]
(b) Lionfish eat parrotfish. With fewer parrotfish grazing on algae, less algae is eaten and algae cover increases. [2]
(c) Counting at several sites reduces the effect of chance variation between individual sites. It allows a mean to be calculated and improves reliability. [2]
(d) Divers could catch lionfish using nets or spears and remove them from the reef. Preventing release of pet lionfish would also help control the invasive population. [2]
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