Meiofauna, nematodes and associated sediment characteristics of the mangrove-colonized banks of Cayenne estuary (French Guiana) during the wet season of 2022

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¿Cómo referenciar?

Los usuarios deben citar este trabajo de la siguiente manera:

Spedicato A, Michaud E, Thouzeau G, Zeppilli D, Le Bec T, Gauchot C, Traunspurger W, Poullaouec M, Devesa J, Michel L, Chauvet P (2026). Meiofauna, nematodes and associated sediment characteristics of the mangrove-colonized banks of Cayenne estuary (French Guiana) during the wet season of 2022. Version 1.7. Institut Universitaire Européen de la Mer. Samplingevent dataset. https://ipt.data-terra.org/resource?r=biodiversity_meiofauna_cayenneestuary_2022&v=1.7

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El publicador y propietario de los derechos de este trabajo es Institut Universitaire Européen de la Mer. Esta obra está bajo una licencia Creative Commons de Atribución/Reconocimiento (CC-BY 4.0).

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Este recurso ha sido registrado en GBIF con el siguiente UUID: 989d55c1-1913-4e1f-bb50-414df53e02ba.  Institut Universitaire Européen de la Mer publica este recurso y está registrado en GBIF como un publicador de datos avalado por GBIF France.

Palabras clave

Samplingevent; Specimen; Nematoda; Mangrove; Benthic habitats; Invertebrates; Meiofauna; French Guiana

Contactos

Cobertura geográfica

Near Cayenne estuary river (French Guiana)

Cobertura taxonómica

N/A

Cobertura temporal

Datos del proyecto

Meiofauna distribution in mangroves is uneven and, when identified at phylum level, its diversity patterns are not consistent from one study area to another, and the structuring variables are different. Nematodes are the most abundant taxon in the meiofauna, and identification at genus level has proved to be more informative. The β-diversity of nematodes on a global scale is determined by the turnover between the biogeographical zones of mangrove distribution (Atlantic and Pacific) and by the nestedness between higher and lower latitudes. On a local scale, the presence or absence of mangroves, tree species and substrate type (sediment, roots or leaves) regulate nematode α-diversity and functional diversity. The micro-scale heterogeneity of mangrove habitats is rarely studied, even though it determines the functional diversity of nematodes. In Mayotte, Martinique and Guadeloupe, the heterogeneity of nematode α-diversity corresponds to the heterogeneity of sedimentary conditions, and anthropogenic activities have a major influence on nematodes. Along the Cayenne estuary, the β-diversity of nematodes is determined by marine inputs downstream and fluvial inputs upstream. Between microhabitats, diversity was highest in the forest. Appropriate redefinition of significant functional traits is required before their use, and a detailed study of a given study area is necessary for the definition of bioindicators.

Personas asociadas al proyecto:

Métodos de muestreo

Samples were collected along three transects positioned at increasing distance from the sea and the town of Cayenne, thus constituting a “site” gradient. The transects were perpendicular to the water flow. - Site “Cri” (4°54’53"N, 52°20’15"W) was located at the mouth of Crique Fouillée, an inlet crossing Cayenne and draining water close to industrial, commercial, and urban activities. - Site “Conf” (4°53’49"N; 52°22’27"W) was located at the intersection between the Montsinery and Cayenne rivers, not far from the Larivot. - Site “Ty” (4°51’31"N, 52°23’59"W) was located in the Cayenne river, 10 km upstream of the estuary mouth. Three stations were sampled per transect, representing a “habitat” gradient: - “BM” on the muddy shore facing the mangrove - “F” in adult mangrove stands behind the shore - “IN” on the transitional area between BM and F, characterized by small roots. Samples were collected one hour before low tide. For each station, we sampled three sediment cores (replicates A, B, C; diameter = 12 cm, height = 20 cm). We collected sub-sample in each core with a syringe of 2 cm diameter and 10 cm length. We then sliced the small syringe in 4 layers from 0-1 cm, 1-3 cm, 3-5 cm, and 5-10 cm depth. Variables measured by core: - Grain size = core A - Meiofauna, pigments (chlorophyll a and phaeophytin a), microbial abundance and biomass, Total Carbon (TC) and Total nitrogen (TN) contents = cores A, B and C An other sediment core was dedicated to Redox potential, pH and temperature measurement. Measurement were made for each sediment layer (0-1 cm, 1-3 cm, 3-5 cm and 5-10 cm) using the WTW MultiLineTM3420 portable digital multiparameter system equipped with redox (Sensolyt ORP900P) and pH-temperature (SenTixTM 950) probes. Instrument precision was 0.01 mV (Eh) and 0.001 pH, the latter calibrated with NIST Buffers. Pore-water salinity was directly measured using a refractometer (1 ppt; practical salinity scale) after extracting a drop of filtered pore water from each layer of sediment (Michaud et al., 2022). After collection, samples for biogeochemical and grain size analyses were frozen at -80°C, while the meiofauna samples were fixed in 10% buffered formalin.

Descripción de la metodología paso a paso:

1. Samples for granulometry, total carbon (TC), total nitrogen (TN) and microbial analyses were freeze-dried (24h at 60°C), gently crushed to powder and homogenized for bulk sediment analyses. Grain size fractions were analyzed with a laser beam diffraction analyzer (Malvern Mastersizer-S2000). Prior to analysis, organic matter was removed and aggregated particles were deflocculated following Sperazza et al. (2004). Grain size fractions were quantified as clay, silt and sand. TC and TN were analyzed by combustion at 930°C using a CHN carbon analyzer (Flash-2000; Thermo Fisher Scientific Inc., Milan, Italy). Due to the lack of carbonates on the FG coast, the organic fraction largely dominates total carbon (Marchand et al., 2003); thus, only the total fraction (TC) was measured (Michaud et al., 2022). The molar TC:TN ratio was calculated and used as a proxy of the refractory or labile nature of the organic matter. Pigment concentrations were determined fluorometrically on a Turner 10-AU fluorometer (Turner design, San Jose, CA, USA), using an acidification step to separate phaeopigments from chlorophyll a. The Chl:Phaeo ratio was determined as an index of the state of pigment degradation. The size of bacterial and archaeal populations was estimated by quantifying the copy number of 16S rRNA genes using qPCR, according to protocols detailed in Fiard et al. (2022). Total DNA extracts quantified by fluorometric assay using a Quantifluor dsDNA kit (Promega) were used as a proxy of microbial biomass.
2. Samples for meiofauna were sieved on 32 µm and 1 mm mesh, stained with Bengal Rose and stored in 4% formaldehyde. The meiofauna was sorted directly on sieved samples using a stereomicroscope (ZEISS Stemi 508), as extraction by the Ludox density gradient method was not efficient due to the high presence of plant debris in the supernatant after centrifugation. During sorting, 150 nematodes were collected randomly per sample, or all individuals if total abundance did not reach 150. We set up to 150 the number of picked nematodes in order to have at least 100 nematodes identifiable, considering that during the mounting procedure some nematodes can be damaged or can be positioned in an unidentifiable way (Bianchelli et al., 2013; Semprucci et al., 2018; Liang et al., 2020). The nematodes were mounted on permanent slides following De Grisse (1969) and identified at genus level with a Leica DM2500 LED microscope according to Platt et al. (1985, 1988), the pictorial key of Warwick et al. (1988), Schmidt-Rhaesa et al. (2014), and the NeMys Online World Database of Nematodes (NeMys eds. 2023).

Metadatos adicionales