Macrofauna associated with the sponge Neopetrosia exigua (Kirkpatrick, 1900) from Mauritius.

The macrofaunal community associated with the sponge Neopetrosia exigua (Kirkpatrick, 1900) were studied across a Mauritian lagoon (West Indian Ocean).  A total of 191 individuals belonging to 18 macro-invertebrate species were found in association with the host sponge collected at depths of 1.4 – 2.7 m.  Polychaetes and amphipods mostly inhabited the sponge canals whereas crabs and brittle stars were found at bases of the sponges.  The most speciose taxon was Crustacea (61%, 11 spp.), followed by Polychaeta (33%, 6 spp.) and Echinodermata (6%, 1 sp.).  However, the most dominant species was the polychaete Haplosyllis djibouitensis (Gravier, 1900) representing 71% of total number of specimens collected.  The number of species and individuals and the diversity index values were positively, but the evenness index values were negatively correlated with the sponge volume and water depth.  The sponge N. exigua provides shelter and food for a number of invertebrates and contributes to the maintenance of biodiversity in the lagoon

Distribution, abundance and ecology of the sponge Spheciospongia vagabunda (Phylum: Porifera, Class: Demospongiae) in a shallow lagoon of Mauritius.

The distribution, abundance and physico-chemical parameters affecting the sponge Spheciospongia vagabunda were studied in a shallow lagoon (Albion) of Mauritius.  Visual censuses were conducted along the 2 Km lagoon and GPS coordinates around sponge assemblages (patches) were noted.  Sponge abundance and ecological parameters were assessed by random throws of quadrats and physico-chemical parameters, including water depth; salinity, pH, and turbidity were noted.   A distribution map of Spheciospongia vagabunda was constructed on Google Earth.  Two distinctive sponge patches with the largest patch averaging 15350 m2 were identified.  Spheciospongia vagabunda in Albion were mostly anchored in the sand which is an unlikely substratum for Poriferans.  Some sponges were also observed next to the seagrass Syringodium filiforme.  Statistical analysis (t-test) showed that there was a significant difference among sponge size between both sponge assemblages (t = 3.01; p < 0.05).  One-way ANOVA analysis indicated that physico-chemical parameters of surrounding water did not influence the sponge abundance within the lagoon.  Spheciospongia vagabunda were mostly distributed in shallow regions (3.3 sponge/m2 at a depth of 1.18 m).  This study adds to the lack of knowledge on Mauritian sponges and also acts as a baseline study for further monitoring of these benthic animals in the Albion lagoon

First records of sponge-associated Actinomycetes from two coastal sponges from Mauritius

Actinobacteria commonly known as actinomycetes are often constituents of the sponge-associated bacterial communities and are well known producers of bioactive compounds.  In the present study, 7 actinomycete species representing 3 genera were successfully isolated from the sponge Spheciospongia vagabunda (Ridley, 1884) and Neopetrosia exigua (Kirkpatrick, 1900) from Mauritius.  The sponge N. exigua hosted a higher actinomycete diversity resulting in 71% of the total number of actinomycete strains recorded.  Streptomyces sp. and Micrococcus sp. were the most common actinomycete genera, both representing 43% of the total actinomycetes isolated from both host sponges.  Actinomycete Isolation Agar was the most effective medium for the selection of actinobacteria, yielding in 57% of the total actinobacterial strains isolated.  This study is the first to report on sponge-associated actinomycete communities from Mauritius and paves the way for future sponge-associated actinobacterial research in the Mascarene region