Assessing the viability of estimating baleen whale abundance from tourist vessels

As Southern hemisphere baleen whales recover, they are again becoming dominant consumers in the Southern Ocean. Key to understanding the present and future role of baleen whales in Southern Ocean ecosystems is determining their abundance on foraging grounds. Distance sampling is the standard method for estimating baleen whale abundance but requires specific logistic requirements which are rarely achieved in the remote Southern Ocean. We explore the potential use of tourist vessel-based sampling, as a cost-effective solution for conducting distance sampling surveys for baleen whales. We aimed to determine if tourist vessel-based surveys could be effective in determining baleen whale abundance in the southwest Atlantic sector of the Southern Ocean. We did this in two parts. First, we used tourist vessel tracks to estimate the likely whale sightings per tourist's vessel voyage to understand how many voyages are needed to meet the model requirements. Second, we simulated the abundance and distributions of four baleen whale species for the study area and sampled them with both non-standardized tourist vessel-based surveys and standardized line transect surveys. Data were modeled using a generalized additive model and results were compared to the original simulated baleen whale abundance and distributions. We show that for the southwest Atlantic, 12-22 tourist voyages are likely required to provide an adequate number of sightings to estimate abundance for humpback and fin whales, and relative estimates for blue, sei, Antarctic minke, and southern right whales. Our analysis suggests tourist vessel-based surveys are a viable method for estimating baleen whale abundance in remote regions.

Influence of heavy metals on the occurrence of Antarctic soil microalgae

Human- and animal-impacted sites in Antarctica can be contaminated with heavy metals, as well as areas influenced by underlying geology and naturally occurring minerals. The present study examined the relationship between heavy metal presence and soil microalgal occurrence across a range of human-impacted and undisturbed locations on Signy Island. Microalgae were identified based on cultures that developed after inoculation into an enriched medium. Twenty-nine microalgae representing Cyanobacteria, Bacillariophyta, Chlorophyta and Tribophyta were identified. High levels of As, Ca, Cd, Cu and Zn were detected in Gourlay Peninsula and North Point, both locations hosting dense penguin rookeries. Samples from Berntsen Point, the location of most intense human activity both today and historically, contained high levels of Pb. The contamination factor and pollution load index confirmed that the former locations were polluted by Cd, Cu and Zn, with these being of marine biogenic origin. Variation in the microalgal community was significantly correlated with concentrations of Mn, Ca, Mg, Fe, Zn, Cd, Co, Cr and Cu. However, the overall proportion of the total variation contributed by all metals was low (16.11%). Other factors not measured in this study are likely to underlie the majority of the observed variation in microalgal community composition between sampling locations.