Meiofauna and free-living nematodes in volcanic sands of a remote South Atlantic, oceanic island (Trindade, Brazil)

Abstract

This study presents patterns of spatial and temporal variation in the meiofaunal community and nematode associations on the volcanic sandy beaches of Trindade Island, a remote oceanic island in the South-east Atlantic Ocean. Samples were collected in August (rainy season) and December 2014 (dry season) on four beaches (Tartarugas, Parcel, Cabritos and Portugueses) at three zones of the intertidal (high, mid and low). A total of 10 meiofaunal groups were found. Copepods (31%) and nematodes (27%) dominated the meiofauna in all beaches and zones, regardless of the season. Nematodes were comprised mainly of non-selective deposit feeders, with a total of 27 genera from 12 families, with Cyatholaimidae, Xyalidae and Oncholaimidae as the most diverse and abundant. Significant differences were found in the meiofaunal community, as well as in nematode associations, among seasons and intertidal zones but not among beaches. The sediment characteristics were the main drivers regulating the structure of meiobenthic fauna in Trindade Island. Our findings are also compared to other studies focusing on the meiofauna and nematodes of oceanic islands with carbonate and volcanic sediments; the major patterns are herein presented.

The Influential Role of the Habitat on the Diversity Patterns of Free-Living Aquatic Nematode Assemblages in the Cuban Archipelago

“…Comparatively less research has been done in tropical ecosystems resulting in a gap of knowledge about diversity patterns (but see studies [23,24] in Kenya, and [25,26] in the Maldives). Recently, some other understudied tropical habitats have recently been surveyed at the species level, such as volcanic sands [27], mangrove sediments [28], and rivers [29].…”

Free-living Nematodes of Brazilian Oceanic Islands: Revealing the Richness in the most isolated marine habitats of Brazil

“…The data presented here were collected from papers available until November 2016, from a PhD thesis [26] , a M.Sc thesis [27] , graduation works [28,29] , Book Chapters [30,31] , and other manuscripts [32,33,34,35,36] . Abstracts published at scientific meetings were not considered.…”

“…Moreover, identification to the species level is very time-consuming and all studies in Brazilian oceanic islands have had an ecological purpose, where genera offer satisfactory and reliable answers for different questions and hypothesis tested [42] . Furthermore, Santos & Venekey [36] stated that identification to the species level in Trindade was not possible due to the very low number of individuals or to the fact that few of them were in perfect conditions to be measured.…”

“…Netto et al [32,34] observed the difference in hydrodynamics between inner and outer areas of Rocas Atoll and considered it as one of the main causes for sediment and faunal characteristics. Concerning Saint Peter and Saint Paul and Trindade, Miranda-Junior et al [30] and Santos & Venekey [36] , respectively, also suggested the influence of hydrodynamic processes on nematodes. Sediments found in all islands, both carbonate and volcanic, and their size (medium to coarse sand in most cases) are possible indications of strong currents and wave stress.…”

“…For this reason, most studies concentrate high sampling efforts in few occasions. This is probably the reason why only Santos & Venekey [36] have attempted to study seasonal patterns of marine nematodes in Brazilian Oceanic Islands so far. This is possibly also the cause for the lack of studies in Fernando de Noronha and Abrolhos Islands.…”