Biodiversity patterns of epipelagic copepods in the South Pacific Ocean: Strengths and limitations of current data bases

searched the dominant ones in terms of their occurrence along the whole period for each of the major current systems defined above. Most of the dominant species in the SPO were repre- sentatives of the Order Calanoida (S1 Table), except for the cyclopoid Oithona similis, which was the dominant species in the CHC, along with Calanus simillimus and Pleuromamma robusta. In the EAC, O. similis and C. simillimus were the dominant species accompanied by Neocalanus tonsus. In the SPSG Calocalanus kristalli, Paracalanus parvus, and Calocalanus plu- mulosus dominated; in the WWD Calocalanus kristalli, Paracalanus parvus and Calocalanus plumulosus were the most recurrent species; in the HCS Paracalanus indicus, Oithona similis and Acartia tonsa prevailed; and finally in the SEC Paracalanus parvus, Calocalanus kristalli and Calocalanus plumulosus were the most dominant ones (S1 Table). For beta diversity and its components turnover and nestedness, the list of dominant species is shown in S2 Table. The dominant species for the mean beta diversity were the Calanoids Acartia longiremis, Calocalanus kristalli, Calocalanus pavo, and Paracalanus parvus, whereas turnover had similar dominant species, except by the substitution of C. pavo by C. plumulosus. Finally, nestedness resulted in a different species assemblage represented by Calocalanus pavo, Euterpina acutifrons, Lucicutia flavicornis, and Mecynocera clausi. The spatial distribution of alpha diversity considering the complete data set with the

curated data (i.e., 377 cells, excluding the -110˚−-170˚ longitudinal band) is shown in Fig 2A. The removal of cells with values of alpha diversity < 10, left 77 cells located at the eastern and western sides of the SPO, that were used for the inverse distance weighted (IDW) technique analysis (Fig 2B), and for the Kriging interpolation (Fig 2C). Those results showed a similar tendency as the ones obtained with Kriging interpolation done to explore the outcome of this approach by using the complete dataset (393 cells, without excluding the -110˚−-170˚ longitu- dinal band), i.e., showing lower values of diversity at the western side of the SPO with a peak in the tropical and temperate zone, decreasing towards higher latitudes, whereas the eastern side showed higher values peaking at the temperate area that decreased towards the Equator and from the coastal towards the oceanic zone (Fig 2B and 2C). When considering family level, the number of cells increased to 399, and the Kriging interpolation presented a pattern with more families observed towards the eastern tropical and equatorial zone, with lower values towards the temperate, subpolar, and western area; whereas its western side showed higher values of families towards the continent with peaks in equatorial and temperate areas, and decreasing towards the open ocean (Fig 2D).When considering genus level, the number of cells increased to 394, and the Kriging interpolation presented a similar pattern to that observed at species level for eastern alpha diversity in Fig 2A and 2B, with clearer peaks in northern Chile and off

Ecuador; whereas its western side showed higher values of genus towards the continent with peaks in equatorial and temperate areas, and decreasing towards the open ocean (S1 Fig). The Shannon-Wiener index of diversity for pelagic copepods exhibited a pattern that varied from that of alpha diversity. For the eastern and western sides of the basin, the higher values were within the moderate range (2.4 and 2.9, respectively), showing different spatial patterns. At the eastern side of the SPO, greater diversity is observed on a coastal band from the temper- ate zone towards the equator, with decreasing values towards the open ocean (Fig 3). At the western side, higher diversity was observed from subtropical areas towards temperate and sub- polar zones, while also showing decreasing values towards the open ocean (Fig 3). To identify the extreme areas in terms of diversity, we used the High/Low Clustering (Getis-Ord G) statistical analysis. This method yielded patterns consistent with those of diver- sity (in terms or species richness) and allowed us to identify most of the hot spots (high values of richness) present in western temperate-subpolar areas off Australia, and in the equatorial area off Peru and Ecuador, decreasing towards the south and into the open ocean (Fig 4). PLOS ONE Biodiversity of copepods in the South Pacific PLOS ONE | https://doi.org/10.1371/journal.pone.0306440 July 11, 2024 8 / 28