Behavioural responses in a congested sea: an observational study on a coastal nest-guarding fish

The deleterious effects of anthropogenic noise on animal communication are nowadays recognised, not only in urban environments but also in terrestrial habitats and along coasts and in open waters. Yet, the assessment of short- and long-term exposure consequences of anthropogenic noise in marine organisms remains challenging, especially in fish and invertebrates. Males of the Mediterranean damselfish Chromis chromis vocalise and perform visual displays (multimodal communication) to attract mates. The frequency-range of courtship vocalisations overlaps with low-frequency noise generated by maritime activities, resulting in a reduced detection distance among conspecifics. We quantified the number of courtship-related visual displays performed by males living in areas with different levels of maritime traffic. We also tried to manipulate ambient noise in the field to test male short-term response to increased noise levels. Males living in busier areas (near to a harbour) performed significantly more visual displays than those living in less congested areas. When exposed to artificially-increased ambient noise level (playback of boat noise), males did not adjust the number of visual displays accordingly. Yet, we note how assessing the actual effect of maritime traffic in marine populations in their natural environments is particularly difficult, as the effects of boat noise cannot be easily disentangled from a variety of other intrinsic or environmental factors, discussed in the paper. We thus present suggestions to obtain more robust analyses of variations of courtship behaviours in territorial fishes. We hope this will facilitate a further understanding of the potential long-term effects of anthropogenic noise, whose analyses should be prioritised in the context of environmental impact assessment, resource management and biodiversity conservation

Tracking Signals of Change in Mediterranean Fish Diversity Based on Local Ecological Knowledge

One of the expected effects of global change is increased variability in the abundance and distribution of living organisms, but information at the appropriate temporal and geographical scales is often lacking to observe these patterns. Here we use local knowledge as an alternative information source to study some emerging changes in Mediterranean fish diversity. A pilot study of thirty-two fishermen was conducted in 2009 from four Mediterranean locations along a south-north gradient. Semi-quantitative survey information on changes in species abundance was recorded by year and suggests that 59 fish species belonging to 35 families have experienced changes in their abundance. We distinguished species that increased from species that decreased or fluctuated. Multivariate analysis revealed significant differences between these three groups of species, as well as significant variation between the study locations. A trend for thermophilic taxa to increase was recorded at all the study locations. The Carangidae and the Sphyraenidae families typically were found to increase over time, while Scombridae and Clupeidae were generally identified as decreasing and Fistularidae and Scaridae appeared to fluctuate in abundance. Our initial findings strongly suggest the northward expansion of termophilic species whose occurrence in the northern Mediterranean has only been noted previously by occasional records in the scientific literature

Sea Urchins Predation Facilitates Coral Invasion in a Marine Reserve

Macroalgae is the dominant trophic group on Mediterranean infralittoral rocky bottoms, whereas zooxanthellate corals are extremely rare. However, in recent years, the invasive coral Oculina patagonica appears to be increasing its abundance through unknown means. Here we examine the pattern of variation of this species at a marine reserve between 2002 and 2010 and contribute to the understanding of the mechanisms that allow its current increase. Because indirect interactions between species can play a relevant role in the establishment of species, a parallel assessment of the sea urchin Paracentrotus lividus, the main herbivorous invertebrate in this habitat and thus a key species, was conducted. O. patagonica has shown a 3-fold increase in abundance over the last 8 years and has become the most abundant invertebrate in the shallow waters of the marine reserve, matching some dominant erect macroalgae in abundance. High recruitment played an important role in this increasing coral abundance. The results from this study provide compelling evidence that the increase in sea urchin abundance may be one of the main drivers of the observed increase in coral abundance. Sea urchins overgraze macroalgae and create barren patches in the space-limited macroalgal community that subsequently facilitate coral recruitment. This study indicates that trophic interactions contributed to the success of an invasive coral in the Mediterranean because sea urchins grazing activity indirectly facilitated expansion of the coral. Current coral abundance at the marine reserve has ended the monopolization of algae in rocky infralittoral assemblages, an event that could greatly modify both the underwater seascape and the sources of primary production in the ecosystem

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Making Sense of Life, Global Activism in the Cyberspace

Several recent works have examined the relationship between social media and social movements in the latest cycle of protest. This paper examines how media activism provides a cross-fertilising communication process by shaping a cosmopolitan imagination. The cases of Adbuster and Avaaz are analysed, as two examples of media activism, equally engaged in changing the state of the world. In this paper; similarities and the differences are highlighted in order to understand how a cosmopolitan imagination, as a new challenge to the global information society, is constructed. The article explores how action shapes an online community, bypassing state borders and takes a form that shares visions, actions and strategies and develops a new common language, representing a balance between two sets of tensions: the politics of universalism versus the acknowledgement of difference and the responsibility for action