First Assessment of the Benthic Meiofauna Sensitivity to Low Human-Impacted Mangroves in French Guiana

Abstract

Bioindicators assess the mangroves ecological state according to the types of pressures but they differ with the ecosystem’s specificities. We investigated benthic meiofauna diversity and structure within the low human-impacted mangroves in French Guiana (South America) in response to sediment variables with various distances to the main city. Contaminant’s concentrations differed among the stations, but they remained below toxicity guidelines. Meiofauna structure (Foraminifera, Kinorhyncha, Nematoda) however varied accordingly. Nematode’s identification brought details on the sediment’s quality. The opportunistic genus Paraethmolaimus (Jensen, 1994) strongly correlated to the higher concentrations of Hg, Pb. Anoxic sediments were marked by organic enrichment in pesticides, PCB, and mangrove litter products and dominance of two tolerant genus, Terschellingia (de Man, 1888) and Spirinia (Gerlach, 1963). In each of these two stations, we found many Desmodora individuals (de Man, 1889) with the presence of epibionts highlighting the nematodes decreased fitness and defenses. Oxic sediments without contaminants were distinguished by the sensitive genera Pseudocella (Filipjev, 1927) and a higher diversity of trophic groups. Our results suggested a nematodes sensitivity to low contaminants concentrations. Further investigations at different spatio-temporal scales and levels of deterioration, would be necessary to use of this group as bioindicator of the mangroves’ ecological status.

Limnospira(Cyanobacteria) chemical fingerprint reveals local molecular adaptation

“…Multiple correspondence analysis (MCA) was performed to identify correlation between tested factors using software R (version). For each tested factor, multiple factor analyses (MFA) and between class analyses (BCA) were performed simultaneously (BC-MFA, code available at https://github.com/Hubas-prog/BC-MFA) on the combined matrix, as describe in Michelet et al 32 . Percentage of total inertia explained (TIE) by the instrumental variable was systematically calculated.…”

Environmental drivers modelling the mangrove Kinorhyncha community along an urban-to-natural gradient in French Guiana (western Atlantic Ocean)

“…The present work is based on sediment samples previously analyzed by Michelet et al (2021); Cepeda et al (2022a) and Fiard et al (2022). The mangrove study area is located at the Cayenne Estuary (French Guiana, western Atlantic Ocean), near to the city of Cayenne (ca.…”

“…In CO 2 vents and deep-sea pockmarks, Kinorhyncha community composition is mainly driven by the accumulation of reduced compounds and pH (A ́lvarez-Castillo et al, 2015;Sańchez et al, 2020;Cepeda et al, 2020a). Michelet et al (2021) conducted a study on meiofauna (focused on nematodes) sensitivity to low human impact in a French Guiana mangrove (western Atlantic Ocean), showing that nematodes might be affected by low contaminant concentrations. These preliminary results also shown that Kinorhyncha reached ca.…”

Fundamental questions in meiofauna—how small but ubiquitous animals can help to better understand Nature

“…The rather high probability of finding new species might attract students with more taxonomic aspirations; whereas the description of unexpected life forms, morphologies, and anatomies might appeal those who want to make their ways into general zoological textbooks (Kristensen, 1983;Kristensen & Funch, 2000). Students and researchers interested in applied sciences might be drawn into working with meiofauna due to their practical role in ecosystem conservation and management, for example, as sentinels in marine and freshwater ecosystems Hägerbäumer et al, 2017) (Q#19) even at low level of anthropogenic impact (Michelet et al, 2021); or in habitats hardly reachable by humans (e.g. deep sea, Ingels et al, 2020) (Q#57).…”