Diatom diversity and distribution in Madeira Island streams (Portugal)

Abstract

Here, we present the data obtained from the samples collected in a field campaign during the spring of 2015 which aims for a better understanding of the diversity and distribution patterns of freshwater diatoms in Madeira Island. Following European and Portuguese standards and recommendations for routine diatom sampling and analysis, we collected samples in 40 sites, distributed in 27 permanent streams and identified the diatom species present, using general diatom floras and studies in Portuguese freshwater diatoms. Little is known about the diversity and distribution of freshwater diatom assemblages from Madeira Archipelago. This study reports a survey in 40 sites in Madeira Island distributed in 27 permanent streams. A total of 965 diatom (Bacillariophyta) occurrences were recorded, belonging to 130 different taxa from 44 genera and 27 families. The families with the highest number of occurrences were Bacillariaceae (176), Achnanthidiaceae (135) and Naviculaceae (133). The two diatom endemisms, described previously in Madeira Island (Lange-Bertalot 1993), Nitzschia macaronesica Lange-Bertalot and Navicula madeirensis Lange-Bertalot, were only observed in a small number of sites, located mostly at Laurissilva forest. Sixty species are new records, not only to Madeira Island, but also to the Madeira Archipelago.

Macaronesia as a Fruitful Arena for Ecology, Evolution, and Conservation Biology

“…For example, the study of Cabo Verde's biota lags behind that of other Macaronesian archipelagos (Romeiras et al, 2020), which is probably associated with the fact that many endemic species only occur in habitats that are difficult to access, such as cliffs in the mountain areas (Neto et al, 2020). Certain taxonomic groups, like Platyhelminthes, Nematoda and Annelida, as well as the Bacillariophyta and Amoebozoa typical of freshwater habitats (but see Ritter et al, 2020;Gonçalves et al, 2021 for Madeira), are still poorly studied in most archipelagos (Figure 2A and ESM1 in Supplementary Material). Even in the case of terrestrial arthropods, a group that has been intensively studied in the last decades, species description is far from complete, with estimates indicating that a large number of species remains unknown (Lobo and Borges, 2010).…”