Seagrass beds are among the most important and studied marine vegetated habitats worldwide, Recently, the supra-littoral deposits of leaf litter (i.e., banquettes), have been investigated as part of the seagrass life cycle, in terms of their nutrients, biomass and associated community. Nevertheless, an overlooked fraction of the seagrass detritus never reaches the shore and sinks far away to deeper seafloor, but the destiny of the leaves transported to deep subtidal habitats remains unknown, even if they might host organisms consuming and processing seagrass carbon far away from the donor bed. Meiofauna is the most abundant and ubiquitous component of the benthos, which could be a useful tool to answer several ecological questions, since plays a key role enhancing energy flow from the microbial community to the entire food web. A huge issue related to meiofaunal research is the lack of information on both taxonomy and community structure, and despite recently this trend is changing, several habitats remain unexplored, such as the deep macerating P. oceanica detritus. This study investigated for the first time the meiofaunal community inhabiting sediments characterized by P. oceanica detritus in a deposit located at 65-80 m depth off Ischia Island (Gulf of Naples, Italy) in the zone D of the MPA “Regno di Nettuno”. The results show that the meiofaunal community appears highly diversified and strongly dominated by nematodes (from 85% to 93%). The nematode community revealed a very high biodiversity (number of families and genera: 31 and 104, respectively), with a clear prevalence of selective and non-selective deposit feeders that suggest the key role of this habitat in the benthic detrital food web. Additionally, two new species of Echinoderes are described: Echinoderes semprucciae sp. nov. and Echinoderes sandullii sp. nov. Both species can be easily distinguished from their congeners by their unique arrangement of cuticular structures and represent the first record of kinorhynchs inhabiting a macerating P. oceanica detrital habitat. This study will possibly draw attention to this peculiar environment that deserves to be deeply investigated given the strong connection to the much betterknown living seagrass beds, which support incredibly diverse community, from tiny invertebrates to large fishes, providing important services to people as well, especially in the Mediterranean Sea.

THE FORGOTTEN POSIDONIA OCEANICA (L.) DELILE DETRITAL HABITAT: NEMATODE COMMUNITY AND TWO NEW SPECIES OF ECHINODERES (KINORHYNCHA: ECHINODERIDAE) INHABITING THIS NEGLECTED ENVIRONMENT

FEDERICA SEMPRUCCI;
2024

Abstract

Seagrass beds are among the most important and studied marine vegetated habitats worldwide, Recently, the supra-littoral deposits of leaf litter (i.e., banquettes), have been investigated as part of the seagrass life cycle, in terms of their nutrients, biomass and associated community. Nevertheless, an overlooked fraction of the seagrass detritus never reaches the shore and sinks far away to deeper seafloor, but the destiny of the leaves transported to deep subtidal habitats remains unknown, even if they might host organisms consuming and processing seagrass carbon far away from the donor bed. Meiofauna is the most abundant and ubiquitous component of the benthos, which could be a useful tool to answer several ecological questions, since plays a key role enhancing energy flow from the microbial community to the entire food web. A huge issue related to meiofaunal research is the lack of information on both taxonomy and community structure, and despite recently this trend is changing, several habitats remain unexplored, such as the deep macerating P. oceanica detritus. This study investigated for the first time the meiofaunal community inhabiting sediments characterized by P. oceanica detritus in a deposit located at 65-80 m depth off Ischia Island (Gulf of Naples, Italy) in the zone D of the MPA “Regno di Nettuno”. The results show that the meiofaunal community appears highly diversified and strongly dominated by nematodes (from 85% to 93%). The nematode community revealed a very high biodiversity (number of families and genera: 31 and 104, respectively), with a clear prevalence of selective and non-selective deposit feeders that suggest the key role of this habitat in the benthic detrital food web. Additionally, two new species of Echinoderes are described: Echinoderes semprucciae sp. nov. and Echinoderes sandullii sp. nov. Both species can be easily distinguished from their congeners by their unique arrangement of cuticular structures and represent the first record of kinorhynchs inhabiting a macerating P. oceanica detrital habitat. This study will possibly draw attention to this peculiar environment that deserves to be deeply investigated given the strong connection to the much betterknown living seagrass beds, which support incredibly diverse community, from tiny invertebrates to large fishes, providing important services to people as well, especially in the Mediterranean Sea.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2750451
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