Setting a baseline for monitoring studies: leukocyte levels in pack-ice seals from western Antarctic Peninsula

NEGRETE JAVIER; DAMICO VERÓNICA; LEONARDI MARÍA SOLEDAD; MÁRQUEZ MARIA E.I.; ROGERS TRACEY L

Leuven

Simposio; XIITH SCAR BIOLOGY SYMPOSIUM; 2017

SCAR

Global warming and its consequences constitute one of the main stressors for organisms worldwide affecting different factors such as the distribution, and abundance of parasites, which in turn can affect the immune system of organisms. Therefore, it is important to have baseline information on immune parameters of organisms in order to make future comparisons in this changing ecological context. The use of haematological parameters such as leukocyte counts is becoming popular in the analysis of health status. Leukocytes are one of the key components of an animal?s immune system, with different leukocyte types offering protection against a variety of parasites and pathogens. In the present study, we report for the first time the leukocyte numbers of three species of Antarctic seals: the Weddell (Leptonychotes weddellii), the leopard (Hydrurga leptonyx) and the crabeater (Lobodon carcinophagus). During the summer 2014/15 and 2015/2016 we sampled 65 seals at Punta Cierva, Danco Coast, Antarctica. We evaluate if exist differences on leukocyte counts among species and presence/absence of ectoparasites. Smears were prepared with a drop of fresh blood and placed on slides, fixed with ethanol and stained. They were examined under a light microscope to obtain total leukocyte counts, proportion of each leukocyte type classified into basophils, neutrophils, eosinophils, lymphocytes, and monocytes, and neutrophil/lymphocyte ratio (N/L) as a physiological stress index. Neutrophils were the most abundant leukocyte type for crabeater and Weddell seals, followed by lymphocytes whereas, leopard seals showed the inverse pattern. Leukocyte numbers showed differences among species. Basophils (H(2,65)= 9.8, p