Biodiversity of intertidal biotopes of Clarence Island (Tierra del Fuego Archipelago, S Chile)

Study Extent

The sampling was carried out as part of an exploratory study of the biodiversity of Clarence Island, located in the Magallanes Region, extending into the Chilean Fjords and Channels Ecoregion (Spalding et al. 2007). The contributions of freshwater from the ice fields of glaciers surrounding Clarence Island and the geomorphology of the area cause the studied locality to have particular and unique marine biodiversity. A part of Clarence Island called Seno Duntze, located on the southeast coast of the Island towards the Cockburn Channel and exposed to the prevailing westerly winds, was described by Palacios Subiabre (2008), who indicated that the coast has an intertidal substrate with little slope, pebble and boulder block granulometry, and sedimentary type rocks. Macrocystis pyrifera is mentioned as the predominant algal species, along with several species of marine invertebrates (Palacios Subiabre 2008).

Sampling

The sampling was carried out with high-quality still camera photographs, which allow the identification of the species in the images. The entire bank of photographs was organized and classified by sampling season, summer and winter. All photos were taken by professionals from biological areas; special care was taken to capture the zone and representation of intertidal biotopes, following the recommendations of John et al. (2003) on intertidal biotopes.

Quality Control

The identification of taxa taken in the photograph was carried out meticulously, using the appropriate specific literature for each taxon plus comparison with samples in institutional collections. Species records and their respective geographic positions of the sites were entered into a spreadsheet, structured using the Standard Darwin Core format (Wieczorek et al. 2012) taxonomically adjusted according to the World Register of Marine Species (WoRMS 2022). The data were submitted in the Integrated Publishing Toolkit, following the standards of the Global Biodiversity Information Facility (GBIF).

Method steps

1. Units of measurement in the study area were defined following a distance gradient, considering sites of interest in fjords and channels on the east coast of Clarence Island, just inside the southeastern boundary of Kawésqar National Park. These units were called transects. Stations were established in front of, around and in the immediate vicinity of each transect. Between 7 and 9 sampling units (stations) were defined, spaced approximately every 500 meters, which gave each transect a maximum coastline prospecting distance of 4.5 kilometers.

All taxa were identified to the lowest possible taxonomic level. The dataset includes 50 species from nine different phyla, belonging four kingdoms.

1. Animalia
   rank: kingdom
2. Chromista
   rank: kingdom
3. Fungi
   rank: kingdom
4. Plantae
   rank: kingdom
5. Bryophyta
   rank: phylum
6. Arthropoda
   rank: phylum
7. Rhodophyta
   rank: phylum
8. Mollusca
   rank: phylum
9. Chlorophyta
   rank: phylum
10. Ochrophyta
    rank: phylum
11. Ascomycota
    rank: phylum
12. Cnidaria
    rank: phylum
13. Echinodermata
    rank: phylum
14. Bryopsida
    rank: class
15. Thecostraca
    rank: class
16. Bangiophyceae
    rank: class
17. Florideophyceae
    rank: class
18. Bivalvia
    rank: class
19. Ulvophyceae
    rank: class
20. Phaeophyceae
    rank: class
21. Lecanoromycetes
    rank: class
22. Gastropoda
    rank: class
23. Polyplacophora
    rank: class
24. Anthozoa
    rank: class
25. Echinoidea
    rank: class
26. Asteroidea
    rank: class

The coast of the Clarence Island, south of the Strait of Magellan, in an intensive sampling area along fjords and channels in the southeast of the island, covering <1 degree of latitude.