Physiological differences of two overlapped breeding Antarctic penguins in a global warming perspective

D´AMICO, V.; CORIA, N.; PALACIOS, M. G.; BARBOSA, A.

Barcelona

Congreso; XIth SCAR Biology Symposium; 2013

Scientific Committee for Antartic Research (SCAR)

Global warming has significantly affected the Antarctic Peninsula in the last years, resulting in a reduction of sea ice, which has been suggested to affect the abundance krill. Antarctic penguins have been particularly affected because their diet is mainly based on krill. In areas where breeding populations overlap, species with a wider prey spectrum should be less affected than krill specialist species which can show a decline in their populations. Human activities (e.g. tourism, scientific bases) can also add to these changes, as penguins are sensitive to anthropic impacts. At Punta Stranger (25 de Mayo/King George Island, SSI) Adélie (Pygoscelis adeliae) and Gentoo (P. papua) penguins breed sympatrically. In the last 10 years, the population of ice-dependent Adélie has shrunk ~60%, whereas the Gentoo one has increased ~70%. The objective of our work was to assess whether physiological parameters of adults and chicks reflect these demographic trends in the colony. Blood samples (N=84) were obtained from the metatarsal vein during the 2012-breeding season. Blood smears were prepared for microscopic analysis, obtaining a complete leukocyte profile, the heterophil to lymphocyte ratio (H/L) and records of erythrocytic nuclear abnormalities (ENA). Blood samples were centrifuged, hematocrit measured and plasma used to determine total protein (gr/dl), triglycerides (mg/dl), cholesterol (mg/dl), and glucose (mg/dl) levels. Adult Adélie showed significantly higher values of basophils, lymphocytes, triglycerides and cholesterol, whereas adult Gentoo displayed higher values of total leukocyte counts (TLC), heterophils and consequently higher H/L. For chicks, TLC, basophils, lymphocytes, and ENA were significantly higher in Adélie, while heterophils, H/L and hematocrit were higher in Gentoo. The presence of higher ENAs in Adélie chicks suggests that they are more sensitive to contaminants than Gentoo ones, as ENAs are known expressions of genotoxicity caused by environmental pollution. On the other hand, leukocyte profiles and blood biochemical parameters do not provide a clear picture. While H/L was higher in Gentoo, the percentage of basophils, another index of stress, was higher in Adélie. Furthermore, some results could be related to differences in diet rather than stress. For instance, Gentoo show greater prey diversity and thus incorporate a richer parasite fauna than Adélie, which could also cause their higher heterophils and H/L. The parameters measured here serve as baseline for a sustained monitoring of these changing populations. Future research will incorporate additional indices of stress, such as levels of corticosterone and oxidative damage, as well as measures of immune function.