Epiphytic diatom community structure and richness is determined by macroalgal host and location in the South Shetland Islands (Antarctica)

Abstract

The marine waters around the South Shetland Islands are paramount in the primary production of this Antarctic ecosystem. With the increasing effects of climate change and the annual retreat of the ice shelf, the importance of macroalgae and their diatom epiphytes in primary production also increases. The relationships and interactions between these organisms have scarcely been studied in Antarctica, and even less in the volcanic ecosystem of Deception Island, which can be seen as a natural proxy of climate change in Antarctica because of its vulcanism, and the open marine system of Livingston Island. In this study we investigated the composition of the diatom communities in the context of their macroalgal hosts and different environmental factors. We used a non-acidic method for diatom digestion, followed by slidescanning and diatom identification by manual annotation through a web-browser-based image annotation platform. Epiphytic diatom species richness was higher on Deception Island as a whole, whereas individual macroalgal specimens harboured richer diatom assemblages on Livingston Island. We hypothesize this a possible result of a higher diversity of ecological niches in the unique volcanic environment of Deception Island. Overall, our study revealed higher species richness and diversity than previous studies of macroalgae-inhabiting diatoms in Antarctica, which could however be the result of the different preparation methodologies used in the different studies, rather than an indication of a higher species richness on Deception Island and Livingston Island than other Antarctic localities.

A Digital Light Microscopic Method for Diatom Surveys

“…In the second approach we used a digital analysis workflow, a slightly modified version of the one previously used by Burfeid-Castellanos et al [19,Fig. 2].…”

“…Until now it has not been widely recognized that such high throughput imaging methods can also usefully supplement a workflow involving "manual" taxonomic identification by human investigators. In our group, we have established such methods in the last years and used them in ecological and morphometrical studies by Burfeid-Castellanos and collaborators [18,19]. These digital methods have, however, not been systematically introduced nor has their effectivity been compared with the traditional light microscopic workflow.…”

Current Trends and Future Directions of Large Scale Image and Video Annotation: Observations From Four Years of BIIGLE 2.0

“…This became apparent when BIIGLE users requested the support for virtual microscopy slides-large images in the gigapixel range-in the image annotation tool. Support for gigapixel image annotation was implemented in BIIGLE in late 2017 and already supported several studies in the marine biology community (Kloster et al, 2020;Burfeid-Castellanos et al, 2021). Gigapixel images differ from regular, smaller images since the original image files cannot be displayed unmodified in a web browser.…”

A Digital Light Microscopic Method for Diatom Surveys Using Embedded Acid-Cleaned Samples

“…Until now it has not been widely recognized that such high throughput imaging methods can also usefully supplement a workflow involving "manual" taxonomic identification by human investigators. In our group, we have established such methods in the last years and used them in ecological and morphometrical studies by Burfeid-Castellanos and collaborators [20,21]. These digital methods have, however, not been systematically introduced nor has their effectivity been compared with the traditional light microscopic workflow.…”