Posidonia oceanicameadows as sponge spicule traps

Abstract

A quantitative study on the sponge spicules present in a series of horizontal core samples, taken at different levels, from a 1.5 m thick living matte within the Posidonia oceanica meadow of Prelo Bay (Eastern Ligurian Sea), has been performed. Sponge spicule amounts were evaluated by microscopical and chemical analyses. From the superficial samples the spicule number decreased until 60-80 cm depth to increase progressively until the deepest studied layer, 140 cm depth. The same results were obtained from the trend of spicule volume and biogenic silica tested by chemical analysis. Among the recognisable spicule types, the most common are oxeas, followed by tylostyles, achantostyles and strongyles. However, oxeas, tylostyles and achantostyles showed the same trend of the entire spicule population, whereas strongyles had an opposite trend with a maximum value at the 80-100 cm depth. According to the hypothesis that the amount of spicules in the sediment is proportional or at least related to the sponge biomass existing in the surrounding area, our data suggest that the sponge assemblage of Prelo Bay should not have been constant in the past 100-200 years. Our hypothesis is that the rapid urban and industrial development that occurred along the Ligurian coast after the Second World War, particularly in the 1960s, had an important impact on the sponge assemblages of the area.

Stability of the sponge assemblage ofMediterranean coralligenous concretions along a millennial time span

“…Sponge spicules represent a powerful tool for the tentative reconstruction of ancient assemblages both from a quantitative (Bertolino et al . ) and qualitative (this paper) point of view. Data from this study, obtained from the most diversified assemblage of the Mediterranean Sea, indicate that the diversity of coralligenous sponges has remained stable over a millennial span of time.…”

“…Similar results were recorded from cores taken from a Posidonia oceanica meadow in the Mediterranean (Bertolino et al . ).…”

Consequences of the marine climate and ecosystem shift of the 1980-90s on the Ligurian Sea biodiversity (NW Mediterranean)

“…Notwithstanding persisting warm-water conditions, recent surveys in the 2010s did not find C. prolifera but C. cylindracea (Montefalcone et al 2015), as predicted by the phase-shift model of Montefalcone et al (2007c) and contrarily to both the successional and the warming hypotheses. The multidecal change observed in the Prelo meadow was mirrored in the modifications of the associated sponge fauna, as reconstructed through the analysis of the siliceous spicules trapped within the matte (Bertolino et al 2012).…”

“…This review aims at describing the most important consequences of the 1980-90s shift on the marine biodiversity of Liguria, searching for common patterns of change through the comparative analysis of existing data series, a few of which have been purposely updated for this review using unpublished information. Some of these data series span several decades Bavestrello et al 2015;Cattaneo-Vietti et al 2015;Gatti et al 2015Gatti et al , 2017Parravicini et al 2015;Burgos-Juan et al 2016;Betti et al 2017a;Costa et al 2018;Montefalcone et al 2018), and a few use retrospective techniques to reconstruct trends for up the last 3000 years (Peirano et al 2004;Bertolino et al 2012Bertolino et al , 2014aBertolino et al , 2017.…”

Long-term turnover of the sponge fauna in Faro Lake (North-East Sicily, Mediterranean Sea)

“…The availability of data focusing on the Mediterranean Sea from the past is basic to perform comparisons for determining possible variations in faunal composition and species richness that may have caused loss or turnover of biodiversity values (Gaino & Pronzato 1989;Gaino et al 1992;Pronzato 1999;Cerrano et al 2000;Occhipinti-Ambrogi & Savini 2003;Bianchi & Morri 2004;Garrabou et al 2009;Por 2009;Bertolino et al 2012Bertolino et al , 2014aBertolino et al , 2016Pronzato et al 2012;Duarte et al 2013;Sukhotin & Berger 2013;Bianchi et al 2014a,b).…”