The increasing human impact and the effects of climate changes are producing a rapid alteration in the marine habitats in Maldivian atolls. Meiofauna is an important benthic component and a good bioindicator of environmental changes. Previous studies have focused attention on meiofauna of shallow water habitats revealing a high biodiversity, while the community from the reef slopes were almost unknown. Thus, a sampling campaign was carried out in May 2013 from Felidhoo and Malé Atolls. Several abiotic factors were considered in this study, among which the type of reef slope (i.e. inner/ outer), depth (from 19 m to 66 m) and inclination (from 10° to 90°). The statistical analysis revealed that the greatest dissimilarities (ANOSIM) of the meiofaunal communities were between types of slope followed by depth while inclination and atoll did not appear significant. The highest meiofaunal diversity was found in the outer reefs. Several uncommon meiofaunal taxa were found, even if nematodes and copepods were the dominant groups within the community. The nematode community included a total of 174 genera, in 37 families mainly represented by Desmodoridae, Chromadoridae and Xyalidae. Like meiofauna, also the nematode fauna resulted mainly influenced by the type of slope. Oncholaimidae and Linhomoidae, families typical of low levels of hydrodynamic conditions were mainly associated with the low wave energy of the inner slopes, whereas Draconematidae and Desmoscolecidae, which are indicators of high hydrodynamic stress, were mainly found in the outer reefs, where ocean currents and waves are strong.
Meiofaunal and nematode biodiversity trends in tropical subtidal habitats.
Grassi E.;Cesaroni L.;Guidi L.;Balsamo M.;Semprucci F.
2019
Abstract
The increasing human impact and the effects of climate changes are producing a rapid alteration in the marine habitats in Maldivian atolls. Meiofauna is an important benthic component and a good bioindicator of environmental changes. Previous studies have focused attention on meiofauna of shallow water habitats revealing a high biodiversity, while the community from the reef slopes were almost unknown. Thus, a sampling campaign was carried out in May 2013 from Felidhoo and Malé Atolls. Several abiotic factors were considered in this study, among which the type of reef slope (i.e. inner/ outer), depth (from 19 m to 66 m) and inclination (from 10° to 90°). The statistical analysis revealed that the greatest dissimilarities (ANOSIM) of the meiofaunal communities were between types of slope followed by depth while inclination and atoll did not appear significant. The highest meiofaunal diversity was found in the outer reefs. Several uncommon meiofaunal taxa were found, even if nematodes and copepods were the dominant groups within the community. The nematode community included a total of 174 genera, in 37 families mainly represented by Desmodoridae, Chromadoridae and Xyalidae. Like meiofauna, also the nematode fauna resulted mainly influenced by the type of slope. Oncholaimidae and Linhomoidae, families typical of low levels of hydrodynamic conditions were mainly associated with the low wave energy of the inner slopes, whereas Draconematidae and Desmoscolecidae, which are indicators of high hydrodynamic stress, were mainly found in the outer reefs, where ocean currents and waves are strong.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.