Diatom assemblages associated with turtle carapaces in the Neotropical region

Abstract

Few studies have explored the ecology and interrelationship with other organisms of the many endangered freshwater turtle species inhabiting the Neotropical Region. The focus of the current study was to shed light on the relationship between Neotropical turtle carapaces and primary producers, insofar as the surface of former constitutes a suitable substrate for the colonization and establishment of the latter. The under-explored relationship between turtle carapaces and the diatom assemblages inhabiting them was investigated and characterized in terms of taxonomic and biological traits (bio-volume, life-form, and attachment). The carapaces of seven native turtle species were surveyed. Among these carapaces, a total of 45 diatom taxa were found, and diatom taxa varied among turtle species. Podocnemis vogli and Podocnemis expansa supported more diverse diatom assemblages than Podocnemis lewyana, Rhinoclemmys diademata, and Rhinoclemmys melanosterna, which were dominated by Navicula spp. Analysis further showed that carapace size did not explain differences in diatom diversity. However, a trait-based analysis suggests that both carapace roughness and an assemblage’s successional stage might explain the differences in assemblage composition. Because turtles can serve as dispersal vectors, characterizing their epibiont diatom assemblages may contribute to our understanding of diatom distribution on larger scales, as well as, give us some clues as to the auto-ecology of turtles that help us to effectively determine conservation areas for these endangered species.

Specificity of diatom communities attached on the carapace of the European pond turtle (<em>Emys orbicularis</em>)

“…Epizoic diatoms were present on the carapace of Emys orbicularis, as previously observed on other freshwater (Donato et al, 2018) and marine (Robinson et al, 2016) turtle species. The numbers of species identified were higher than those reported in previous works (Soylu et al, 2006;Robinson et al, 2016;Wu and Bergey, 2017;Donato et al, 2018). This can be explained by differences in sampling protocols or by the higher diversity of diatoms in the sites explored in this study.…”

“…Other studies have shown quite different distributions of diatom life forms attached to turtles. In the study of seven freshwater turtle species, a common feature of epibiotic diatoms was the quasi absence of solitary species in favour of colonial forms (Donato et al, 2018), while in the study of seven marine turtle species, adnate forms were dominant (Robinson et al, 2016). Although differences with other substrates were found for the sites Sav and Ver, there is apparently no universal functional community profile characterizing the turtle epizoic habitat.…”

“…Because of their ubiquitous nature and high specific diversity, benthic forms are widely used as biological indicators of water quality (Poulíčková and Manoylov, 2019). The last decade has seen a growing interest in diatoms on turtle shells (Wetzel et al, 2010;Majewska et al, 2015;Wu and Bergey, 2017;Donato et al, 2018;Vassal et al, 2020). It is possible to distinguish species-level studies focusing on the search for new taxa, probably specific to epizoic habitat (Wetzel et al, 2012;Majewska et al, 2020) and others at the level of diatom com-munities, focusing on variations observed at the host individual level, or between turtle populations or species (Fayolle et al, 2016;Robinson et al, 2016;Wu and Bergey, 2017).…”

Diatomeas epizooicas en hembras de tortuga golfina (Lepidochelys olivacea) en estadio de desove en Playa Ventura, Guerrero, México

“…Estudios realizados con distintas especies de tortugas de agua dulce nativas de la región neotropical indican la presencia de diatomeas como uno de los grupos más diversos y con mayor prevalencia sobre los caparazones de estos reptiles, además sugieren que la rugosidad del caparazón junto al estado de sucesión y la capacidad de adherencia puede explicar esta composición diatomológica. Las características morfológicas de las diatomeas pennadas facilitan la adherencia a distintos sustratos debido al mucilago (lipoproteínas) que generan, además de que se han reportado con una amplia distribución y frecuentes tanto en ambientes eutróficos como oligotróficos (Donato- Rondón et al, 2018;Valdivia, 2019).…”