Fish fauna of a mixed meadow composed by the seagrasses Cymodocea nodosa and Zostera noltii in the Western Mediterranean

Abstract

The fish fauna of a shallow meadow composed by the seagrasses Cymodocea nodosa and Zostera noltii was studied in the Gulf of Olbia (NE Sardinia, Italy; Western Mediterranean). Visual censuses were conducted monthly from August 1995 to August 1996. Environmental variables for water temperature, salinity and seagrass shoot density were collected on each sampling occasion. A total of 23 fish species from eight families were recorded. Planktivorous species (Atherinids) numerically dominated the fish community, followed by necto-benthic fish, chiefly Labrids and Sparids. There was no discernible trend in total fish density. Species richness, diversity, evenness and density of necto-benthic species, instead, displayed a distinct seasonal pattern, higher values occurring from late spring to early autumn. All community variables, except total fish density, were positively related to water temperature and shoot density, but not to salinity. Multivariate analysis revealed variation in species composition and relative abundances of the fish community throughout the year. The most common fish species displayed different seasonal patterns of density throughout the year. Differences were also found in the relationships between the relative abundances of each species with the environmental variables (water temperature, salinity) and the seagrass shoot density. The data show that the fish fauna of the meadow of Olbia was characterised by a distinct seasonal variation of the community structure, probably influenced by the fluctuations of both environmental variables and habitat complexity. Since seasonal variations in fish density were due to the contribution of juvenile, sub-adult and adult specimens, the data presented here imply both recruitment and migration phenomena from and towards adjacent habitats in the colonisation of the bed during warmer months. The presence of juvenile fishes of a number of species emphasises the potentially important function of nursery exerted by such seagrass systems during the first phases of the life history of several fish species. © 2000 Ifremer/CNRS/IRD/É ditions scientifiques et médicales Elsevier SAS fish fauna / seagrasses / seasonal variations / Mediterranean Résumé-Ichtyofaune d'une pelouse mixte à Cymodocea nodosa et Zostera noltii en Méditerranée occidentale. La faune ichtyologique associée aux phanérogames marines méditerranéennes de petite taille (Cymodocea nodosa et Zostera noltii) à été étudiée près d'une pelouse mixte peu profonde dans le golfe d'Olbia (Sardaigne nord-orientale, Italie). Des recensements visuels ont été réalisés mensuellement d'aoû t 1995 à aoû t 1996. La température, la salinité de l'eau et la densité des faisceaux ont été mesurées à chaque échantillonnage. Un total de vingt trois espèces de poissons, appartenant à huit familles, ont été recensés. Les poissons planctonophages (Atherinidae) dominent toute l'année, suivis par les poissons necto-benthiques (Labridae et Sparidae). La densité totale des poissons ne présente pas de variations saisonnières. Par contre,...

Timing and habitat preferences for settlement of juvenile fishes in the Marine Protected Area of Torre Guaceto (south-eastern Italy, Adriatic Sea)

“…In terms of habitat preferences, investigated using the juvenile density as a proxy, Spondilyosoma cantharus and Diplodus annularis were mostly associated to marine phanerogams (especially small-sized seagrasses) for settlement. Similar results for these two species were reported from other Western Mediterranean locations (Francour & Le Direach 1994;Harmelin-Vivien et al 1995;Biagi et al 1997;Guidetti & Bussotti 1997;Tunesi et al 1997;Guidetti 2000;Guidetti & Bussotti 2000). This shows their strict association with marine phanerogams, even though it is long been known that they can use additional/alternative vegetated habitats (e.g.…”

“…Mullus surmuletus chiefly used sublittoral sandy habitats in SE Italy. Other authors found similar patterns, but also reported that juveniles of this species can be found associated with marine phanerogams (Garcia-Rubies & Macpherson 1995;Guidetti & Bussotti 2000) or can be collected in open waters far from the coast (Deudero 2002). Juveniles of Chromis chromis were always found to be chiefly associated with sublittoral rocks composed by blocks and boulders.…”

Composition and structure of the molluscan assemblage associated with a Cymodocea nodosa bed in south-eastern Spain: seasonal and diel variation

“…The faunistic communities of Posidonia oceanica have been thoroughly studied over the last decades (Russo et al 1984a, b;Templado 1984;Gambi et al 1992;Sánchez-Jerez et al 1999;Francour 1997), and the same applies to the communities associated with Zostera marina (Jacobs and Huisman 1982;Jacobs et al 1983;Currás et al 1993;Mattila et al 1999;2009a, b;. In contrast, the fauna of C. nodosa beds have scarcely been studied (García-Raso et al 2006;Barberá et al 2001;Guidetti and Bussotti 2000;Sánchez-Jerez et al 1999;Ledoyer 1966;Sfriso et al 2001;Brito et al 2005), especially with regard to the temporal patterns of molluscan assemblages (Chemello et al 1997;Terlizzi and Russo 1997;Tuya et al 2001). In addition to seasonal changes, there is a diel variability related to short-term movements of the animals during the day-night cycle along the seagrass shoots or from adjacent habitats.…”

Fish assemblages of shallow intertidal habitats of the Ria Formosa lagoon (South Portugal): influence of habitat and season

“…Although the abundant presence of Atherinidae species (e.g. Atherina boyeri and A. presbyter) in south European estuaries and coastal areas (Atlantic and Mediterranean) is well known (Labourg et al 1985, Bouchereau et al 2000, Guidetti & Bessotti 2000, the abundant presence of YOY from Atherinidae family in intertidal areas of European saltmarshes is not well documented. However, in shallow littoral zones along the U.S. coast, species of the Atherinidae family (e.g.…”