Distribution of Atlantidae species (Gastropoda: Pterotracheoidea) during an El Niño event in the Southern California Current System (summer-fall 2015)

Abstract

Atlantids are holoplanktonic gastropods present in tropical to sub-polar waters, and have gained an increasing interest due to their potential use as biological indicators of climate change and ocean acidification. However, there is a lack of information regarding their distribution for large areas of some oceans, particularly in the California Current System (CCS), which has been used as a model for many acidification studies and where intense warming events occur. The distribution patterns of 18 species of Atlantidae off the west coast of the Baja California Peninsula, Mexico, representing 90% of the atlantid species registered for the Pacific Ocean, were analyzed during a period of warm anomalies associated with the El Niño of 2015-2016 and the 2014-2016 marine heat wave (MHW). The species distribution showed 3 groups: 2 in the north (coastal and oceanic) and 1 in the south. The limit of distribution between these 3 groups was found in the vicinity of Punta Eugenia (PE). The southernmost community of atlantids was characterized by tropical and subtropical species that were transported northward due to coastal advection of warm waters associated with the El Niño of 2015-2016. North of PE, the warm-water affinity oceanic species Atlanta rosea and A. fragilis were found, evidencing the entrance of water from the Central Pacific related to MHW which affected the oceanic region off the coast of PE. The response of the distribution patterns proves that atlantids can be used as biological indicators, as they reflect the effect of environmental anomalies in the southern CCS.

Diversity of planktonic gastropods from western Baja California Peninsula assessed by 18S rDNA sequences

“…A relatively high planktonic gastropod diversity was observed in the present study as compared to that found in 2 sites of the Caribbean Sea: 31 species (Oliva-Rivera & Navarrete, 2007) and 34 species (Chávez-Villegas et al, 2014), but lower than the 62 holoplanktonic species from the Gulf of California (Angulo-Campillo et al, 2011), the 6 species of the order Thecosomata (Sánchez-Hidalgo y Anda, 1989), and the 18 species of the family Atlantidae off the BCP (Aceves-Medina et al, 2020;Moreno-Alcántara et al, 2020). Nevertheless, according to a preliminary rarefaction analysis (results not shown due to reduced sample size) the actual species diversity in our study region is probably under-represented.…”

“…Planktonic dispersal in the marine environment is one of the leading connectivity processes among populations of meroplanktonic and holoplanktonic gastropods (Crocetta et al, 2020;Roegner, 2000), and is a relevant element of the trophic dynamics of ecosystems and indirect indicators of the health of adult populations (Campos & Landaeta, 2016;Chávez-Villegas et al, 2014). Planktonic dispersal study will aid in a better understanding of the molluskan community's behavior under present and future environmental conditions (e.g., Aceves-Medina et al, 2020;Molina-González et al, 2018). For this purpose, baseline studies on the species composition that rely on the use of genetic markers are a starting point.…”

“…Planktonic gastropods have been quite extensively studied worldwide (Bandel et al, 1997;Campos & Landaeta, 2016;Chávez-Villegas et al, 2014;Oliva-Rivera & Navarrete, 2007). However, in northwestern Mexico, the main efforts have been in the study of the species composition of holoplanktonic mollusks in the Gulf of California (Angulo-Campillo et al, 2011) and the western coast of the Baja California Peninsula (BCP) (Aceves-Medina et al, 2020;Molina-González et al, 2018;Moreno-Alcántara et al, 2020;Sánchez-Hidalgo y Anda, 1989), characterizing these regions as highly diverse. However, there is no available information about meroplanktonic gastropods in the region.…”