Ecological drivers of testate amoeba diversity in tropical water bodies of central Mexico

Abstract

Testate amoebae are unicellular organisms characterized by a shell-like test. Due to their potential use as bioindicators (and paleoindicators), these organisms have been increasingly studied in the last decade, particularly in temperate latitudes. This study's objective was two-fold: to identify the testate amoeba communities sampled from 29 water bodies in Mexico and to determine if their presence and distribution also made them suitable bioindicators for tropical latitudes. A total of 40 taxa were recorded within 12 genera, and six significant variables -oxygen, pH, depth, temperature, conductivity, and total alkalinity -that explained testate amoeba distribution within and among the water bodies were identified through a canonical correspondence analysis. The Q-mode clusters rendered five assemblages, each named after their respective dominant species: 1) Centropyxis aculeata strain "aculeata" assemblage, 2) Difflugia oblonga strain "bryophila" assemblage, 3) diverse assemblage, 4) Cucurbitella tricuspis assemblage, and 5) Difflugia protaeiformis strain "acuminata" assemblage. We found that Cucurbitella tricuspis and the Difflugia protaeiformis strain "acuminata" have similar ecological preferences to those reported previously for temperate lakes, with the former identified as an indicator of eutrophic environments and the latter as an indicator of low oxygen levels. On the other hand, Centropyxis aculeata strain "aculeata" and Arcella vulgaris seem to indicate adverse conditions, but the source of this environmental stress apparently differs from that reported in temperate latitudes. Although this stress source could not be identified in all cases, our study nonetheless demonstrates that testate amoebae in the water bodies of central Mexico could reveal the presence of environmental stress.

Testate amoebae (Amoebozoa: Arcellinidae) as indicators of dissolved oxygen concentration and water depth in lakes of the Lacandón Forest, southern Mexico

“…3). Both testate amoebae are typical opportunistic species, recorded in hostile conditions in tropical, subtropical and temperate environments with very low pH and high salinity, and even in badly polluted waters (Dalby et al, 2000;Patterson and Kumar, 2000;Escobar et al, 2005;Sigala et al, 2018). Our results confirm this interpretation, as these two taxa were found in sites with low dissolved oxygen concentrations (Fig.…”

“…A few studies in the Neotropics identified the effect of dissolved oxygen on the structure of testate amoebae communities (Dalby et al, 2000;Roe et al, 2010;Sigala et al, 2018). Our goal was to evaluate the role of dissolved oxygen concentration in determining the structure and diversity of testate amoebae communities in lakes of the Lacandón Forest, Chiapas, México.…”

Geodiversity primarily shapes large-scale limnology and aquatic species distribution in the northern Neotropics

“…These global species richness patterns contrast with Latitudinal Diversity Gradient theory, that postulates increase of biodiversity from poles to the Ecuador (Mannion et al, 2014;Schumm et al, 2019). Interestingly, a similar pattern is observed in other aquatic microorganisms in the northern Neotropics, such as testate amoebae (Sigala et al, 2016;Sigala Regalado et al, 2018;Charqueño-Celis et al, 2019), chironomids (Hamerlík et al, 2018), andcladocerans (Vázquez-Molina et al, 2016;Wojewódka et al, 2016). The low species diversity per lake in the northern Neotropics may be related to local environmental and evolutionary processes that have taken place recently in the geological time, namely during the Pleistocene and Holocene.…”

Imprints of the Little Ice Age and the severe earthquake of AD 2001 on the aquatic ecosystem of a tropical maar lake in El Salvador

“…However, this genus is ecologically versatile with some species also living on macrophytes (Scenario 1 and 2). Predominance of Goeldichironomus along with the presence of the testate amoeba Arcella discoides (Charqueño-Celis et al, 2020; Sigala Regalado et al, 2018) suggests hypoxic conditions, at least temporarily (Figure 2). Furthermore, high water levels with more diluted waters (low carbonate content) could have created unfavourable conditions for ostracod development.…”