Meiofaunal Diversityand Nematode Assemblages in Two Submarine Caves of a Mediterranean Marine Protected Area

Abstract

Submarine caves are environments of great ecological interest because of the occurrence of peculiar conditions, such as the attenuation of light and reduced water turnover, which can determine oligotrophic conditions from the entrance to the interior part of the cave. These environmental gradients may influence the distribution of the communities inhabiting submarine caves. In this study we investigated the meiofaunal community and nematode assemblages from the sediments inside and outside two submarine caves in Ustica Island Marine Protected Area (southwest Italy): Grotta Falconiera and Grotta dei Gamberi. Consistently with a general pattern of distribution reported by several studies on benthic organisms, our results showed a decrease in the abundance and changes in the taxa composition of the meiofaunal community along the exterior-interior axis of the caves, also highlighting the dissimilarity between the dark and semi-dark communities. We found a significant influence of the availability of organic matter (i.e. phytopigment concentrations) on the distribution and composition of both the meiofauna and the nematode community inside the caves. Different nematode assemblages characterized the inside and the outside of the two caves, with species occurring exclusively in the sediment of both caves, particularly in the dark portions, and completely absent in the external sediments. Environmental features of submarine caves may affect food resources inside the caves and consequently trophic nematode assemblages. Our results showed a difference in feeding strategies between nematodes inhabiting the caves and those living outside, suggesting that in the two caves investigated, bacteria might represent the most important food source for nematodes.

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

“…This likely reflected an important role of the immigration of nematode species from adjacent coral reef environments such as Paradesmodora immersa, Pomponema sp., and Zalonema ditlevseni. Other studies in submarine caves have reported different findings with the dominance of either non-selective deposit feeders or omnivores/predators [85,86].…”

Characteristics of meiofauna in extreme marine ecosystems: a review

“…However, some efforts were made in the past (i.e. Wieser 1954;Pesta 1959) and more recently (Palacin and Masalles 1986;Palacín et al 1992;Grimaldi de Zio et al 1982a, b;Villora-Moreno 1996;Sandulli et al 1999;Todaro et al 2006;Ape et al 2015;Janssen et al 2013). Several marine caves in the Mediterranean Sea, Atlantic Ocean and Australia have been investigated for the presence of meiofauna.…”

Evaluation of Water Variables in No-Take Zone of Ustica Marine Protected Area (Southern Tyrrhenian Sea)

“…TRIX index, used to characterizing succinctly the trophic levels of the coastal marine area, shows that Ustica MPA has moderately productive waters with good transparency and average trophic level, highlighting even in autumn, similar characteristics to the open sea. Our research can be considered as a sort of integration of the knowledge of this MPA; in fact, several studies and observation have been conducted on flora, fauna and other topics, principally on the coastal fish and molluscan assemblage (37)(38)(39)(40)(41)(42), but no data have been published on water variables. Water column analyses represent an essential topic in the evaluation of all water environments.…”