Descriptors of Posidonia oceanica meadows: Use and application

The conservation of the coastal marine environment requires the possession of information that enables the global quality of the environment to be evaluated reliably and relatively quickly. The use of biological indicators is often an appropriate method. Seagrasses in general, and Posidonia oceanica meadows in particular, are considered to be appropriate for biomonitoring because of their wide distribution, reasonable size, sedentary habit, easy collection and abundance and sensitivity to modifications of littoral zone. Reasoned management, on the scale of the whole Mediterranean basin, requires standardized methods of study, to be applied by both researchers and administrators, enabling comparable results to be obtained. This paper synthesises the existing methods applied to monitor P. oceanica meadows, identifies the most suitable techniques and suggests future research directions. From the results of a questionnaire, distributed to all the identified laboratories working on this topic, a list of the most commonly used descriptors was drawn up, together with the related research techniques (e.g. standardization, interest and limits, valuation of the results). It seems that the techniques used to study meadows are rather similar, but rarely identical, even though the various teams often refer to previously published works. This paper shows the interest of a practical guide that describes, in a standardized way, the most useful techniques enabling P. oceanica meadows to be used as an environmental descriptor. Indeed, it constitutes the first stage in the process. (c) 2005 Elsevier Ltd. All rights reserved.Peer reviewe

Sur la richesse floristique de certains peuplements photophiles infralittoraux de Port-Cros (Var, France)

An account is given of the infralittoral phytobenthos (Rhodophyta, Phaeophyceae, Chlorophyceae) of Port-Cros Island (France). From 2 to 10 m depth, under calm conditions, up to 109 species were listed for each 400 cm² quadrat sample. It must be emphasised that these species numbers are considerable, and that the part played by algae in the photophilous settlements is conspicuous or even dominant

Végétation marine de l'île de Port-Cros (Parc National): 23. Sur deux espèces de <i>Griffithsia</i> (Ceramiaceae, Rhodophyta) = Marine vegetation of Port-Cros Island (National Park): 23. On two <i>Griffithsia</i>species (Ceramiaceae, Rhodophyta)

Griffithsia barbata (Smith) C. Agardh and G. tenuis C. Agardh are described from material principally collected at Port-Cros I. (France-Mediterranean Sea); the ecology, phenology and chlorology are given. The specimens of G. tenuis from the Mediterranean Sea are different from these of the tropical Atlantic and Indo-Pacific Ocean by the structure of their spermatangial heads (firstly described for the Mediterranean Sea) and their tetrasporocysts. As a result the authors point out that extramediterranean G. tenuis auct . should be named differently as the type of this species is coming from the Mediterranean Sea

Végétation marine de l'Ile de Port-Cros (Parc National): 11. Sur <i>Acrochaetium molinieri</i> sp. nov. et <i>Lophosiphonia cristata</i> Falkenberg

Acrochaetium molinieri sp. nov. is characterized by its bicellular base; only one of these cells originates an erect filament. Lophosiphonia cristata, rarely mentioned from the Mediterranean, is richly illustrated and described in detail

Végétation marine de l'ile de Port-Cros (Parc National): 22. Sur quelques Ceramiaceae (Rhodophyta) = Marine vegetation of Port-Cros Island (National Park): 22. On some Ceramiaceae (Rhodophyta)

Five species of Ceramiaceae are illustrated, namely Antithamnion crusciatum (C.Agardh) Nägeli, Antithamnion heterocladum Funk, Ceramium circiatum (Kützing) J.Agardh, Lejolisia mediterranea Bornet and Spermothamnion johannis Feldmann-Mazoyer. Their ecology and phenology at Port-Cros I. (Mediterranean Sea, France) are given

Végétation marine de la Corse (Méditerranée): 6. Documents pour la flore des algues = Végétation marine de la Corse (Méditerranée): 6. Documents pour la flore des algues

Ten benthic marine algae are mentioned for the first time for Corsica: 1 Chrysophyceae, 1 Xanthophyceae and 8 Florideophyceae. Their geographical distribution and data on their morphology and anatomy are given. Dasyopsis penicillata is studied in detail; its systematic position is discussed

Un nouveau genre de Peyssonneliaceae, <i>Metapeyssonnelia</i> (Rhodophyta)

Metapeyssonnelia, a new genus of the Peyssonneliaceae (Rhodophyta), is described. This encrusting orbicular alga is completely calcified by aragonite. Small unicellular rhizoids are present. The centre of the thallus shows a Peyssonnelia-like structure that metamorphes towards the margins of older thalli: in these metamorphosed parts, an inferior perithallus is generated downwards. Each hypothallic cell gives rise to only one coxal cell, even in the metamorphosed parts: this characteristic distinguishes the structure of Metapeyssonnelia from that of Polystrata. The type species is M. feldmannii nov. sp., collected at Port-Cros island (Mediterranean, France)