Over 10 years of variation in Mediterranean reef benthic communities

Abstract

During the last several decades, the Mediterranean littoral shallow water benthic communities have suffered significant changes in their structure and taxa composition. Despite numerous studies conducted to characterize these changes at various levels, it has always been very difficult to disentangle the effects of natural factors from anthropic ones. The main purpose of this work was to evaluate possible changes, over a 10-year scale, in diversity and abundance of the most representative species of the benthic communities considered to be primarily and potentially affected by natural stressors in a highly protected area. Sets of macro-photographs were taken in 2002â\u80\u932003 of three sites inside a small bay called Caâ\u80\u99 dell'Oro, which is the â\u80\u9cno entryâ\u80\u94no takeâ\u80\u9d zone of the Marine Protected Area of Portofino, in order to analyse the structure of the benthic communities at different depths over a short time scale. The same sampling was repeated 10Â years later in 2013. In the 10-year span, a significant change in the macroalgal coverage and composition was observed, while the overall richness and coverage of species remained almost unchanged. This process resulted in a significant reduction of the habitat complexity of the three-dimensional algal components. Likewise, a remarkable change in terms of presence and abundance occurred among all zoobenthic components. The benthic communities seem to have suffered from detrimental effects probably caused by climatic events that have been occurring in recent years in the Ligurian Sea

Pycnogonids (Arthropoda: Pycnogonida) of Portofino, Ligurian Sea (North-Western Mediterranean Sea)

“…The upper infralittoral zone of Portofino hosts a rather rich benthic fauna (e.g. Bertolino et al 2016;Betti et al 2017;Longobardi et al 2017) and this is supported by our study of the Pycnogonida. The number of species identified in our study is close to that recorded by Chimenz et al (1979) in the Civitavecchia harbor in the Tyrrhenian Sea.…”

“…Some studies, driven by mass mortality following water warming events (e.g. Cerrano et al 2000;Schiaparelli et al 2007;Cerrano & Bavestrello 2008), focused on the long-term changes in structure and composition of the benthic communities (Bertolino et al 2016;Betti et al 2017;Longobardi et al 2017).…”

The park never born: Outcome of a quarter of a century of inaction on the sea‐floor integrity of a proposed but not established Marine Protected Area

“…The barnacle Perforatus perforatus and the scleractinian coral Leptopsammia pruvoti (as well as Balanophyllia europaea and Caryophyllia inornata ), common in 1991, were not found again in subsequent years. A decadal study (2002–2013) at Portofino MPA (about 80 km east of Gallinara) obtained the same result, and seawater warming has been invoked as a putative cause (Betti et al, ; Longobardi, Bavestrello, Betti, & Cattaneo‐Vietti, ). In the case of sponges, the results were contradictory: Scalarispongia scalaris , a major component of APO in 1991, disappeared, possibly as a result of summer heat waves in the late 1990s (Cerrano et al, ); Sarcotragus foetidus became more abundant, as observed in other Mediterranean areas (Bianchi et al, ); and Axinella polypoides , a species protected under the European Habitats Directive (Longo et al, ), became more scarce.…”

Effects of global warming on reproduction and potential dispersal of Mediterranean Cnidarians

“…An emblematic case study is the cold-affinity species Paracoryne huvei Picard, 1957. This species is apparently present only in winter months whereas in the warmer period it forms cysts (Bouillon 1975): temperature seems to affect only the occurrence and length of the life cycle of this species while rainfall has effects on the settlement/development of the colonies (Betti et al 2017b). Therefore, its strict stenothermic feature and shortened life cycle (due to water warming and low salinity conditions) seem to make it suitable as bioindicator of climatic change (Betti et al 2017b).…”