Associated mollusc communities of a Posidonia oceanica meadow in Cap Zebib (off North East Tunisia)

The aim of this work is to study the temporal dynamics of rhizome epiphytes and sessile animals living on the rhizomes of the seagrass Posidonia oceanica in the east of Tunisia. on a fringing reef located in Chebba. Rhizomes were sampled by SCUBA diving at three stations. Samples were examined with a microscope to estimate the cover of macroinvertebrate and macroalgal organisms on the top 10 cm of each rhizome. Results revealed a high diversity of epiphytes on P. oceanica rhizomes with a dominance of red and brown algae, ascidians, and bryozoans. Distinct temporal changes were observed in Oued Lafrann, with a high January cover (winter period) for all groups. These winter increases can be attributed to: (i) the low phenological parameters of P. oceanica in winter that reduce the effects of shading, (ii) life cycles of the epiphytes and invertebrates, (iii) water motion and (iv) grazing.

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“…; Belgacem et al . ). Preference of sea urchins for epiphytes can be attributed to their high nutritional value (Alcoverro et al .…”

Section: Discussionmentioning

confidence: 97%

Diversity and temporal fluctuations of epiphytes and sessile invertebrates on the rhizomesPosidonia oceanicain a seagrass meadow offTunisia

2013

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“…) or the temporal and depth distribution of micro‐ and macroepiphyte leaves on P. oceanica leaves (Belgacem et al . ,b; Mabrouk et al . ).…”

Section: Introductionmentioning

confidence: 99%

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

et al. 2014

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A study was undertaken of the patterns of spatial variability, epiphytic biomass and distribution of epiphytic fauna and flora of Posidonia oceanica. Samples were taken at four stations located approximately 4 km apart, exposed to different current conditions. Stations A and B, situated near the Oued Mimoun tidal channel with its relatively strong bi‐directional flows, were affected by high current tide. The other two stations, North Oued Mimoun (L1) and South Oued Mimoun (L2), were located further from the channel, in low current tide conditions. Sampling was conducted in the Attaya area of Kerkennah Island (Tunisia) in August 2009 at depths between 2 and 3 m, with the results indicating differences among the stations. Shoot density decreased when exposed to high levels of hydrodynamic activity generated by current tides whereas the epiphytic biomass of P. oceanica leaves decreased at sheltered stations located far from the channel. Epiphytic algae such as Heterokontophyta, Rhodophyta and Chlorophyta, and epiphytic fauna represented by Bryozoa, Hydrozoa, Annelida, Porifera and Tunicata, dominated the epiphytic assemblages and were abundant at the station most exposed to high current tide hydrodynamics. Cyanobacteria, however, were dominant in stations exposed to low current tide.

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“…Indeed, the epiphytes of marine macrophytes are a food source for a range of grazers and, in turn, they influence the diversity and abundance of epiphytes by removing the substrate and biomass of the host plant [38]. The effect of grazing is also an important factor that contributes to the variation between the two macrophytes species, as many species feed on epiphytes of Posidonia, including the echinoid Paracentrotus lividus, some decapods, and amphipods [45,46]. In addition, about 50 species of fish are encountered in P. oceanica beds [47].…”

Section: Discussionmentioning

confidence: 99%

“…Some grazers (scrapers) feed preferentially on tightly attached diatoms [46], whereas others (surfers) favor overstory diatoms [49]. Neckles et al [50] have shown that number of diatoms decreased in the presence of grazers.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Abundance and Diversity of Epiphytic Microalgal Assemblages on the Leaves of the SeagrassesPosidonia oceanica(L.) andCymodocea nodosa(Ucria) Asch in Eastern Tunisia

Mabrouk

Hamza²,

Mahfoudhi³

et al. 2014

Journal of Marine Biology

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We studied spatial patterns in assemblages of epiphytic microalgae on the leaves of two seagrass species with different morphologies and longevity, Cymodocea nodosa and Posidonia oceanica, which cooccur in Chebba in Eastern Tunisia. Epiphyte assemblages were described for each species in summer. Epiphyte microalgal assemblages were more abundant on the leaves of C. nodosa but more diversified on the leaves of P. oceanica. We suggest that the differences in species composition and abundance between those seagrass species may reflect an interaction of timescales of seagrass longevity with timescales of algal reproductive biology. Short-lived C. nodosa was dominated by fast growing species such as the cyanobacteria species Oscillatoria sp., while P. oceanica leaves were colonized by more mature and diversified species such as Prorocentrales. Local environmental conditions (hydrodynamics, light penetration), host characteristics (meadow type, shapes forms of leaves, life span, and growth rate), and grazing effect seem also to be responsible for these dissimilarities in epiphytic microalgae communities.

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Associated mollusc communities of a Posidonia oceanica meadow in Cap Zebib (off North East Tunisia)

Cited by 12 publications

References 10 publications

Diversity and temporal fluctuations of epiphytes and sessile invertebrates on the rhizomesPosidonia oceanicain a seagrass meadow offTunisia

Diversity and temporal fluctuations of epiphytes and sessile invertebrates on the rhizomesPosidonia oceanicain a seagrass meadow offTunisia

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

A Comparison of Abundance and Diversity of Epiphytic Microalgal Assemblages on the Leaves of the SeagrassesPosidonia oceanica(L.) andCymodocea nodosa(Ucria) Asch in Eastern Tunisia

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