Results

Dietary remains recovered from both abandoned and modern Adelie penguin colonies at Rothera consisted of a wide variety of prey species (Tables 1 and 2). As at Palmer Station, the most abundant dietary remains found at all of the sites were Antarctic Silverfish and the mesopelagic squid.

Through time, Pleuragramma antarcticum displays similar trends between the Minimum Number of Individuals (MNI) and the volume corrected values [MNI / Sediment Volume (L)]. During the time period 2750-1220, there was a slight discrepancy between the two in which the volume corrected value from 1490-1220 was higher than that of the previous time period 2750-1715; the opposite trend was displayed with the MNI values. Peak volume corrected values of P. antarcticum occurred in the time period of 2750-1220. The lowest values occurred on either side of the peak at 720-405 and 3975-3265. Samples taken from the modern colonies also contained high values of P. antarcticum (Figure 1). After correcting for the volume amount of sediment, the MNI of P. antarcticum varied significantly between sites of different ages.

MNI and volume-corrected values of Psychroteuthis glacialis display identical trends through time. Peak values of squid were found in the modern colonies and also in the time period 720-405. As years (BP) increase, both the MNI and the MNI/ Sediment Volume (L) declines (Figure 2). Although higher numbers of squid occurred in younger sites, after correcting for volume, the MNI did not vary significantly between sites of different ages (X², df = 6, p> 0.25).

Table 1 (below). Fish species identified from otoliths found at both abandoned and modern Adelie penguin colonies at Rothera. The time periods are given in years BP. For the purposes of this study, modern colonies are those that are less than approximately 300 years old. The values given for each prey item per time period are the Minimum Number of Individuals (MNI) / Sediment Volume (L).

Table 2 (below). Cephalopod species identified from beaks found at both abandoned and modern Adelie penguin colonies at Rothera. The time periods are given in years BP. For the purposes of this study, modern colonies are those that are less than approximately 300 years old. The values given for each prey item per time period are the Minimum Number of Individuals (MNI) / Sediment Volume (L).

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