Extreme environmental events can strongly affect coastal marine ecosystems but are typically unpredictable. Reliable data on benthic community conditions before such events are rarely available, ...making it difficult to measure their effects. At the end of October 2018, a severe storm hit the Ligurian coast (NW Mediterranean) producing damages to coastal infrastructures. Thanks to recent data collected just before the event on two Posidonia oceanica seagrass meadows hit by the storm, it has been possible to assess the impact of the event on one of the most valuable habitats of the Mediterranean Sea. By means of seagrass cover and depth data gathered along four depth transects positioned within the two meadows in areas differently exposed to the storm waves, and by using models (WW3® + SWAN + XBeach 1D) to evaluate wave height and bed shear stress, we showed that meadows experienced erosion and burial phenomena according to exposure. Paradoxically, meadows in good conditions suffered more damage as compared to those already suffering from previous local anthropogenic impacts. Besides the direct effect of waves in terms of plant uprooting, a major loss of P. oceanica was due to sediment burial in the deepest parts of the meadows. Overall, the loss of living P. oceanica cover amounted to about 50%. Considering that previous research showed that the loss of the original surface of P. oceanica meadows in 160 years due to anthropogenic pressures was similarly around 50%, the present study documented that an extreme environmental event can generate in a single day a loss of natural capital equal to that produced gradually by more than a century of human impact.
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•Extreme weather events may affect severely the submerged benthic habitats.•Posidonia oceanica meadows halved their living cover.•The loss of P. oceanica in one day equate that lost in 160 years by human impact.
•A quantitative and synthetic index of ecological complexity (OCI) was developed.•OCI was applied to a marine coastal tract including a Marine Protected Area.•OCI components (structural, functional, ...extensive, intensive) were identified.•The habitats included in the area were characterised according to their complexity.•Suggestions for the management of the area were proposed according to results.
The novel Overall Complexity Index (OCI) is proposed to measure ecological complexity, incorporating four complexity indices: (1) exergy and (2) throughput as extensive metrics, (3) specific exergy and (4) information as intensive metrics. Exergy and specific exergy estimate structural complexity while throughput and information functional complexity. OCI was applied to benthic habitats in a coastal marine tract encompassing a Marine Protected Area (MPA) in north-western Italy. The four individual indices did not always show homogeneous results in assigning complexity to different habitats. On the contrary, the additive measure provided by OCI showed that seagrass meadows and coralligenous reefs are in all the most complex habitats. Applying OCI provided results consistent with traditional approaches based on expert judgement, which usually attach more interest to seagrass meadows and hard bottoms with respect to soft bottoms, but expressed a synthetic, objective and quantitative approach. OCI can be mapped for management purposes, resolving the discordances evidenced by the individual indices. Ecological complexity in the study area is concentrated in some hot spots, as mapped by OCI, while the greatest part of the seafloor is occupied by low complexity habitats. Only some of these complexity hotspots are included within the Marine Protected Area, while this study suggests that high complexity areas, adjacent to the existing MPA, should be considered for protection possibly reshaping MPA's limits.
A rapid visual assessment (RVA) approach for the characterization and assessment of the integrity of coralligenous reefs was applied in 21 stations subjected to different levels of anthropogenic ...pressure, along the French Mediterranean coasts. The reefs were characterized from both the geomorphologic and bionomic (biotic cover, conspicuous species richness, canopy-forming species, etc.) points of view, and their health status was estimated through the COARSE (COralligenous Assessment by ReefScape Estimate) index. The sensitivity of the COARSE index and the robustness of the RVA approach to observer biases were analyzed. Results showed that most coralligenous reefs were characterized by (sub) vertical cliffs or platforms with variable slope, usually dominated by biotic facies with Paramuricea clavata and/or Eunicella cavolini in healthy stations, or by algal associations or facies of impoverishment in the most impacted situations. The overall quality scores of the COARSE index generally reflected the putative level of stress of the sampling stations; differences due to observer biases resulted negligible. Coupling the RVA approach with the COARSE index proved an effective protocol for both the characterization and the evaluation of coralligenous reefs: the former is achieved by the analysis of the whole complexity of this habitat, the latter provides for the first time an indication of sea-floor integrity, differently from previous indices that aim at estimating water quality.
•The use of more indices raise possibilities of discordance among responses.•New graphical approach to obtain an overall expression of seagrass health.•Area is a measure of the overall environmental ...quality.•Circularity is a measure of the consistency among indices.•Consistency among indices is a good proxy of habitat resilience.
Biotic indices are major tools recommended by the European Directives for assessing the ecological status of marine coastal ecosystems such as Posidonia oceanica meadows. Nevertheless, the multitude of available metrics commonly adopted in the P. oceanica monitoring often provide diverging responses about the health status of the habitat. In this study, we investigated the effectiveness and consistency of a set of 11 indices and descriptors working at different level of ecological complexity of P. oceanica ecosystem (individual, population, community, and seascape), applying them on 13 seagrass meadows of the Ligurian Sea (NW Mediterranean). A new approach, named RESQUE (RESilience and QUality of seagrass Ecosystem), is here proposed and aims to provide a single and comprehensive measure of the ecological status of seagrass meadows. RESQUE is a graphical approach that involves the calculation of both the Relative Area Index (RAI) and the Relative Circularity Index (RCI) starting from a radar chart where all the different values of indices and descriptors are reported after being normalized. The RAI represents a measure of the overall environmental quality, while the RCI constitutes a measure of the consistency among indices and it is assumed as a good proxy of meadow resilience. RESQUE turned out to be an effective method to incorporate all the different indices responses, and allowed integration of relevant information into an overall expression of meadow health. Beyond the ability of merely defining the quality of the Ligurian P. oceanica meadows, this approach displayed a great potential being possibly applicable to other habitats and with ideally infinite combinations of metrics.
•Data of ESCA index from 2009 to 2018 were collated and reviewed.•ESCA values of 42 sites were compared with an anthropization index.•ESCA detected differences among sites subjected to different ...levels of pressure.•ESCA discriminated disturbed and control sites in three impact evaluation studies.•ESCA was stable respect to the regional spatio-temporal variability.
This paper aims at collating and reviewing all data collected using the ESCA (Ecological Status of Coralligenous Assemblages) index from 2009 to 2018 during different local applications, in order to evaluate at large spatial scale its effectiveness and temporal variability. To this scope, the large-scale response of ESCA to anthropogenic disturbance was tested comparing ESCA values calculated at 42 sites of the Western Mediterranean Sea with the anthropization index. Moreover, the sensitivity of ESCA to punctual human disturbance and the robustness of the index across the natural space and time variability were evaluated. The large spatial scale study showed significant correlation between ESCA and the anthropization index, while very low correlation was detected when descriptors of ESCA (i.e., sensitivity levels, α-diversity, and β-diversity) were considered separately. The three impact evaluation studies highlighted significantly lower values of the ESCA index in disturbed conditions than in the control ones. The coastal monitoring study confirmed the robustness of the index which showed a high ecological quality of coralligenous reefs in reference conditions compared to more anthropized sites, and this pattern was maintained throughout the ten years study period. Application of the ESCA index to different situations tested positively its sensibility to different levels and type of human disturbance and its stability with respect to regional spatio-temporal variability. This confirm the reliability of the ESCA index already tested on the local and annual scale, thus broadening its range of application and validating it on a wider space–time scale.
More than 60 marine non-indigenous species (NIS) have been removed from previous lists and 84 species have been added, bringing the total to 986 alien species in the Mediterranean 775 in the eastern ...Mediterranean (EMED), 249 in the central Mediterranean (CMED), 190 in the Adriatic Sea (ADRIA) and 308 in the western Mediterranean (WMED). There were 48 new entries since 2011 which can be interpreted as approximately one new entry every two weeks. The number of alien species continues to increase, by 2-3 species per year for macrophytes, molluscs and polychaetes, 3-4 species per year for crustaceans, and 6 species per year for fish. The dominant group among alien species is molluscs (with 215 species), followed by crustaceans (159) and polychaetes (132). Macrophytes are the leading group of NIS in the ADRIA and the WMED, reaching 26-30% of all aliens, whereas in the EMED they barely constitute 10% of the introductions. In the EMED, molluscs are the most species-rich group, followed by crustaceans, fish and polychaetes. More than half (54%) of the marine alien species in the Mediterranean were probably introduced by corridors (mainly Suez). Shipping is blamed directly for the introduction of only 12 species, whereas it is assumed to be the most likely pathway of introduction (via ballasts or fouling) of another 300 species. For approximately 100 species shipping is a probable pathway along with the Suez Canal and/or aquaculture. Approximately 20 species have been introduced with certainty via aquaculture, while >50 species (mostly macroalgae), occurring in the vicinity of oyster farms, are assumed to be introduced accidentally as contaminants of imported species. A total of 18 species are assumed to have been introduced by the aquarium trade. Lessepsian species decline westwards, while the reverse pattern is evident for ship-mediated species and for those introduced with aquaculture. There is an increasing trend in new introductions via the Suez Canal and via shipping.
Coral reefs are amongst the most diverse ecosystems in the biosphere. However, they also represent one of the most threatened marine systems. Apart from global change, especially fishing and tourism ...affect coral reefs either with mechanical damage or with increase of pollution and sedimentation. Recently, the increase of disturbances has induced extensive changes in community structure and composition of coral reefs. Well-balanced and rich communities can better resist disturbances and show a more rapid recovery, compared to less biodiverse systems.
This study assesses the status of coral reefs subjected to several anthropogenic pressures, using a modified version of Coral Condition Index (CCI) that takes into account all Acropora and Pocillopora growth forms and considers a further category of coral damage: the presence of disease. The investigations were carried out at Bangka Island (North Sulawesi, Indonesia), where some of the most flourishing reefs in the country are present. The CCI takes into account the extent of different damages on coral colonies, particularly of the genera Acropora and Pocillopora, being among the most widespread bioconstructors of local coral reefs and very sensitive to anthropogenic disturbances. The aim of the present work is to test whether the CCI is a reliable index in different coral reefs, and to evaluate if highly biodiverse reefs show a better resistance to several human stressors.
Data showed high values of CCI (0.9 on average) at all the investigated sites and at the two depths (3 and 9m) for each site, with the most abundant category represented by “healthy coral colonies”. These data indicate a reasonably good health status of the reef in the study area (CCI>0.8). The presence of different types of human pressure in the study area was evaluated through the use of metric proxies. Results do not seem to show any significant influence of such human activities on reef coral status, as shown by the low values of correlation between CCI values and the distances of the study sites from the three main sources of stress (Villages, Resorts and Other). Moreover, the present data seem to confirm that highly biodiverse and well-structured assemblages can resist disturbances more efficiently and that human pressure in the study area is sustainable. Compared to fishing activities, the impact of Scuba diving on coral reef is lower, resulting more sustainable and ecologically non-destructive.
CCI summarizes many kinds of information and can be applicable in various areas with different pressures. It is a useful tool that might help to assist and guide management decisions towards alternative development models.
A rapid temperature increase in the 1980-90s has been accompanied by dramatic and unprecedented changes in the biota and communities of the Ligurian Sea. This review uses existing historical series ...(a few of which have been purposely updated) to assess extent and consequences of such changes. A number of warm-water species, previously absent or occasional in the comparatively cold Ligurian Sea, has recently established thanks to warmer winters. Occurrence among them of invasive alien species is causing concern because of their capacity of outcompeting autochthonous species. Summer heatwaves, on the other hand, caused mass mortalities in marine organisms, some of which found refuge at depth. New marine diseases appeared, as well as other dysfunctions such as the formation of mucilage aggregates that suffocated and entangled benthic organisms. Human pressures have combined with climate change to cause phase shifts (i.e., abrupt variations in species composition and community structure) in different habitats, such as the pelagic environment, seagrass meadows, rocky reefs, and marine caves. These phase shifts implied biotic homogenization, reduction of diversity, and dominance by invasive aliens, and may be detrimental to the resilience of Ligurian Sea ecosystems. Another phase of rapid warming has possibly started in the 2010s and there are clues pointing to a further series of biological changes, but data are too scarce to date for proper assessment. Only well addressed long-term studies will help understanding the future dynamics of Ligurian Sea ecosystems and their possibilities of recovery.
The state-of-art on alien species in the Mediterranean Sea is presented, making distinctions among the four subregions defined in the EU Marine Strategy Framework Directive: (i) the Western ...Mediterranean Sea (WMED); (ii) the Central Mediterranean Sea (CMED); (iii) the Adriatic Sea (ADRIA); and (iv) the Eastern Mediterranean Sea (EMED). The updated checklist (December 2010) of marine alien species within each subregion, along with their acclimatization status and origin, is provided. A total of 955 alien species is known in the Mediterranean, the vast majority of them having being introduced in the EMED (718), less in the WMED (328) and CMED (267) and least in the Adriatic (171). Of these, 535 species (56%) are established in at least one area.Despite the collective effort of experts who attempted in this work, the number of introduced species remains probably underestimated. Excluding microalgae, for which knowledge is still insufficient, aliens have increased the total species richness of the Mediterranean Sea by 5.9%. This figure should not be directly read as an indication of higher biodiversity, as spreading of so many aliens within the basin is possibly causing biotic homogenization. Thermophilic species, i.e. Indo-Pacific, Indian Ocean, Red Sea, Tropical Atlantic, Tropical Pacific, and circum(sub)tropical, account for 88.4% of the introduced species in the EMED, 72.8% in the CMED, 59.3% in the WMED and 56.1% in the Adriatic. Cold water species, i.e. circumboreal, N Atlantic, and N Pacific, make up a small percentage of the introduced species, ranging between 4.2% and 21.6% and being more numerous in the Adriatic and less so in the EMED.Species that are classified as invasive or potentially invasive are 134 in the whole of the Mediterranean: 108 are present in the EMED, 76 in the CMED, 53 in the Adriatic and 64 in the WMED. The WMED hosts most invasive macrophytes, whereas the EMED has the lion’s share in polychaetes, crustaceans, molluscs and fish.
► Geospatial model of human pressures/ecosystems status relationship was developed. ► Approach applied on a MPA coexisting with a commercial harbor. ► Ecosystems status due to variation in the ...cumulative human pressure was predicted. ► MPA conservation effort is expected to balance harbor influence. ► Model implemented into GIS is a decision-support tool for ecosystem management.
Human use of ecosystem resources and services is increasing worldwide, generating pressures that alter ecosystem structure, functioning and provision of services. Unexpected ecosystem change is becoming frequent, and the complex ways through which multiple human pressures may interact leave conservation practitioners and natural resource managers faced with high uncertainty. We developed a geospatial approach for modeling the complex relationships between multiple human pressures and coastal ecosystems status. This framework was then used to produce maps of the expected status of marine coastal ecosystems resulting from variation in the cumulative human pressure. The geospatial modeling approach we developed was tested on an emblematic study case requiring marine spatial planning, i.e. a recently established marine protected area (MPA) that will have to coexist with the expansion of a close commercial harbor. In the study case presented, our modeling approach was used to predict the status of coastal ecosystems resulting from different management alternatives. Results showed that should Port Authority support MPA in reducing human pressures in the area, coastal ecosystems would not be expected to further deteriorate as a consequence of harbor expansion. Our approach proved effective in modeling complex interaction among multiple pressures (e.g. synergisms) and predicting potential future scenarios. The implementation of this approach into geographical information systems (GIS) allows managers to represent the expected outcomes of their planned conservation efforts, thereby representing an important decision-support tool for finding efficient management solutions in the face of complex interactions and high uncertainty.
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