| Summary: | The number of Red Knots Calidris canutus wintering at the Banc d'Arguin, Mauritania, has declined over the last two decades. The fact that food densities in this relatively undisturbed ecosystem have increased suggests that the reason for the declining Knot abundance needs to be sought elsewhere along the flyway. With the Wadden Sea acting as a major stopover site for Red Knots wintering at the Banc d'Arguin (at least in spring), we hypothesize that the declining food stocks in the Wadden Sea are responsible for the reduced number of Red Knots wintering in Mauritania. Speculating further, we bring up the idea that the declining Red Knot population has led to reduced predation pressure on the bivalve stocks at the Banc d'Arguin, which may be the reason why food densities in Mauritania have gone up. Others have brought up an alternative, but non-mutually exclusive, hypothesis explaining this increase by an increased algal production. With production rates in individual shellfish presumably being under strong density-dependent control, the reduced predation hypothesis (in contrast to the alternative hypothesis) predicts lower per capita shellfish production rates nowadays than two decades ago.
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