Figure 1.
Map of the southern Indian Ocean with the main islands, oceanic fronts and zones.
In black, sampling localities, with the sampled penguin species in parentheses. Abbreviations: NRP, northern rockhopper penguin; SRP, southern rockhopper penguin; MP, macaroni penguin; KP, king penguin; GP, gentoo penguin; EP, emperor penguin; AP, Adélie penguin; STF, Subtropical Front; SAF, Subantarctic Front; PF, Polar Front; STZ, Subtropical Zone; SAZ, Subantarctic Zone; AZ, Antarctic Zone [24].
Table 1.
Feather isotopic signatures of seven penguin species in 2006 and 2007, and pair-wise isotopic differences between the two years.
Table 2.
Historic (1900s, 1950s, 1970s) and contemporary (2000s) carbon isotopic signatures of penguin feathers.
Table 3.
Historic (1900s, 1950s, 1970s) and contemporary (2000s) nitrogen isotopic signatures of penguin feathers.
Figure 2.
Correlation between inter-annual differences in penguin featherδ13C values and in sea-surface Chl a (corresponding years).
Values are mean ± SE. Numbers in parentheses indicate sample sizes (N = 70). Solid line represents the linear regression (y = 20.87x+0.20, r = 0.354 and p = 0.003). Abbreviations: AP, Adélie penguin; GP, gentoo penguin; KP, king penguin; MP, macaroni penguin; NRP and SRP, northern and southern rockhopper penguins, respectively.
Figure 3.
Long-term trend in anomalies of feather δ13C values (corrected by Suess and phytoplankton fractionation effects).
Anomalies were calculated independently for each subantarctic and subtropical penguin species (except the king penguin, see text for details). In the 1970s, δ13C anomalies were significantly lower than in the 1900s and 2000s (p<0.0001 and p<0.001, respectively).