Ecological status improvement over a decade along the Ligurian coast according to a macroalgae based index (CARLIT)

According to the Water Framework Directive, within 2015 European Union countries must reach and maintain the "good" Ecological Status (ES), quantified through indices based on key biological elements as indicators. Along the Ligurian shallow rocky coasts (NW Italy), a macroalgae based index (CARtography of LITtoral and upper-sublittoral benthic communities, CARLIT), calibrated according to national characteristics and management needs, has been applied by the Regional Environmental Agency over the last ten years. In 2015, at least a "good" ES was achieved in all Ligurian water bodies except one, located in the Eastern Ligurian coastline, characterized by the lack of the most sensitive species, Cystoseira amentacea var. stricta. A general ES improvement has been observed along the Ligurian coastline, also in comparison with other quality indices (macroinvertebrates and fecal bacteria), and in particular in the Genoa water body, as proved by a relevant increase of C. amentacea abundance, probably as a consequence of enhancement in wastewater treatments. In the present study, the reliability of the observed improvement of the ES over a decade has been assessed, teasing apart intra-seasonal and operator-related variability. These results support the reliability of monitoring procedures carried out though the CARLIT Index and highlight the need and the effectiveness of reduction measures for anthropogenic impacts in order to achieve the ES required by European directives

Pattern and intensity of human impact on coral reefs depend on depth along the reef profile and on the descriptor adopted

Coral reefs are threatened by multiple global and local disturbances. The Maldives, already heavily hit by the 1998 mass bleaching event, are currently affected also by growing tourism and coastal development that may add to global impacts. Most of the studies investigating effects of local disturbances on coral reefs assessed the response of communities along a horizontal distance from the impact source. This study investigated the status of a Maldivian coral reef around an island where an international touristic airport has been recently (2009-2011) built, at different depths along the reef profile (5-20 m depth) and considering the change in the percentage of cover of five different non-taxonomic descriptors assessed through underwater visual surveys: hard corals, soft corals, other invertebrates, macroalgae and abiotic attributes. Eight reefs in areas not affected by any coastal development were used as controls and showed a reduction of hard coral cover and an increase of abiotic attributes (i.e. sand, rock, coral rubble) at the impacted reef. However, hard coral cover, the most widely used descriptor of coral reef health, was not sufficient on its own to detect subtle indirect effects that occurred down the reef profile. Selecting an array of descriptors and considering different depths, where corals may find a refuge from climate impacts, could guide the efforts of minimising local human pressures on coral reef

El papel del acoplamiento pelágico-bentónico en la estructuración de las comunidades litorales bentónicas en la bahía de Terra Nova (Mar de Ross) y en el Estrecho de Magallanes

In Antarctic and peri-Antarctic regions, benthic communities are persistent in time and show high biomass and large numbers of individuals, mainly consisting of suspension and deposit feeders. In fact, apart from recruitment, the major factor structuring these communities is the high flow of organic matter from the pelagic domain to the bottom, representing an important energy source for the benthic organisms. The aim of this paper is to review, compile and compare the data from earlier investigations in Terra Nova Bay (Ross Sea) and the Straits of Magellan, in order to come to a more general conclusion about the role of the pelagic-benthic coupling in structuring littoral benthic communities in southern coastal areas. Few measurements of flux rates and the biochemical composition of the sinking particles occurring in Antarctic and peri-Antarctic shallow waters are available, but a compilation of our own data and others allows a comparison of these two systems. The different environmental conditions between Antarctica and the Straits of Magellan lead to differences in the origin of the particulate organic matter and in its biochemical composition, and consequently in the coupling between pelagic and benthic domains. At Terra Nova Bay the summer particulate matter shows a high labile fraction of a good food value: its flux has been evaluated at about 0.67 g m-2d-1. Conversely, the Straits of Magellan show multi-structured ecosystems where the quality and quantity of the organic matter flux towards the bottom change according to the local geomorphology and current dynamics. Moreover, the three-dimensional assemblages of suspension-feeders, so common in Antarctic shallow waters, seem to be absent in the Magellan area. In particular sponges, gorgonarians and bryozoans play a secondary role inside the Straits of Magellan, where polychaetes (60%) and molluscs (9-10%) are dominant on soft bottoms, and where they reach high values in density and biomass. Bivalves seem to play an important role in both regions: for instance, at Terra Nova Bay, the scallop Adamussium colbecki processes about 14 % of the total carbon flux, with an assimilation efficiency of 36 %. This scallop seems to be able to adapt its reproductive period and its trophic behaviour to the changes in the quality and quantity of the pelagic events. The pulsing trend of the vertical flux, which in a few weeks can reach the total annual input, produces significant changes in the physiology (growth, reproduction, spawning) and trophic behaviour of many benthic species, such as sponges and polychaetes. The study of the pelagic-benthic coupling could be essential in the evaluation of the trophic capacity and the environmental response around sites of sea-farming, which are an ever-growing activity in the Magellan area.En las regiones Antártica y periantártica, las comunidades bentónicas son persistentes en el tiempo y muestran altos valores de biomasa y número de individuos. Estas comunidades están constituídas, principalmente, por organismos suspensívoros y detritívoros. Aparte del reclutamiento, el factor más importante en estructurar estas comunidades es el flujo de materia orgánica desde la zona pelágica al bentos, lo que representa una importante fuente de energía para los organismos del fondo. No obstante la gran importancia de la producción primaria como suministro de alimento para las comunidades béntonicas litorales, la información sobre la tasa de flujo y la composición bioquímica del material que sedimenta es reducida. Muestreos rea lizados con trampas de sedimento han mostrado altos valores de flujo de materia orgánica caracterizado por una elevada presencia de paquetes fecales, particularmente importantes en el transporte de materia orgánica desde la zona fótica a las aguas profundas. En Bahía Terra Nova (Mar de Ross) la materia orgánica estival presenta una fracción lábil importante, un alto valor alimentario y un flujo que se evaluó en aproximadamente 0.67 g m-2d-1. Las diferentes condiciones ambientales de la Antártida y el Estrecho de Magallanes ocasionan diferencias en el origen y en la composición bioquímica de la materia orgánica particulada y, consecuentemente, en el acoplamiento entre los dominios pelágico y bentónico. El Estrecho de Magallanes, contrariamente a las observaciones hechas en la Antártida, muestra un sistema de flujo de materia orgánica hacia el fondo , debido a su geomorfología peculiar y a la dinámica de las corrientes. Por otra parte, los agrupamientos tridimensionales de suspensívoros, comunes en las aguas someras antárticas, parecen estar ausentes en el área del Estrecho de Magallanes. Particularmente esponjas, gorgonias y briozoos desempeñan un papel secundario en el interior del Estrecho de Magallanes, donde poliquetos (60%) y moluscos (9-10%) dominan en los fondos blandos, alcanzando altos valores de densidad y biomasa. Los bivalvos desempeñan un papel importante en ambas regiones: en la Bahía de Terra Nova, el pectínido Adamussium colbecki procesa aproximadamente el 14% del flujo total de carbono, con una eficiencia de asimilación del 36%. Este pectínido sería capaz de adaptar su periodo reproductivo y su estrategia trófica a los cambios en la calidad y la cantidad de materia orgánica. Los pulsos del flujo vertical, que en pocas semanas puede alcanzar el suministro total anual, producen cambios significativos en la fisiología (crecimiento, reproducción, freza) y en el comportamiento trófico de algunas especies bentónicas, como esponjas y poliquetos. Finalmente, el estudio del acoplamiento bentos-pélagos puede ser esencial en la evaluación de la capacidad trófica y la respuesta ambiental para la ubicación de zonas de cultivos marinos, actividad en continuo crecimiento en el área de Magallanes

First ex situ outplanting of the habitatforming seaweed Cystoseira amentacea var. stricta from a restoration perspective

In the Mediterranean Sea, brown algae belonging to the Cystoseira genus play a valuable role as foundation species. Due to evidences of regression/loss of the habitats of these species caused by the interplay of human and climatic disturbances, active restoration measures have been encouraged by EU regulations. In particular, nondestructive restoration techniques, which avoid the depletion of threatened species in donor populations, are strongly recommended. In the framework of the EU project ROCPOP-Life, the first ex situ outplanting experience of Cystoseira amentacea var. stricta has been implemented in the Cinque Terre Marine Protected Area (northwestern Mediterranean). A total of 400 clay tiles, hosting approximately three mm-long germlings of C. amentacea, were fixed to the rocky shore with screws: the tiles were monitored for the next 2 months by photographic sampling, and survival (presence/absence of juveniles on the tiles), cover and growth were assessed. Additional sampling was performed 6 months after tile deployment, after which an unprecedented storm surge severely affected the restoration performance. After 2 months, over 40% of the tiles were covered with Cystoseira juveniles, which reached approximately eight mm in total length. The tiles that survived the storm hosted three to six cm-long juveniles. The high cover (25%), assuring moisture and shading, and the appropriate size of the juveniles, to avert micro-grazing, at time of deployment were key to the survival and growth of the outplanted juveniles, increasing the potential for restoration success. Our findings show that outplanting of midlittoral canopy-forming species is a feasible approach for restoration efforts, with particular attention given to the early phases: (i) laboratory culture, (ii) transport, and (iii) juvenile densities. These results are strongly encouraging for the implementation of restoration actions for C. amentacea on a large scale, in light of EU guidelines

Addressing reproductive stochasticity and grazing impacts in the restoration of a canopy-forming brown alga by implementing mitigation solutions

1. The worldwide decline of marine forests, due to human impacts and climate change, emphasizes the need to develop and implement effective and sustainable solutions to restore these endangered habitats and to re-establish the services they provide. 2. In this study, the ex situ restoration of Treptacantha barbata, a Mediterranean subtidal habitat-forming species of brown seaweed, was for the first time implemented in a marine protected area in the Adriatic Sea. Two restoration efforts were performed in 2019. The first one was started in winter, after a marine heatwave that triggered early fertility, the second one in spring, when the species usually reproduces. 3. This study aimed to evaluate: 1) the disruptive effects of a thermal anomaly on the reproductive biology and performance in culture of T. barbata; and 2) the impact of the grazing pressure on juveniles after the outplanting. 4. The first cultivation was more productive than the second one, in terms of zygote release and germling growth. To mitigate the low efficiency of the second culture and to avoid prolonged highly-demanding maintenance in the mesocosms, the cultivation period was extended outdoors using a structure suspended in the water column. 5. The modular frames conceived for outplanting T. barbata proved to be effective because of their easy operability and low cost. Controlling for herbivorous fish had significant positive effects on both juvenile survival and growth. 6. The outcomes highlighted that an unpredictable climatic event and fish grazing were major threats that impaired the restoration process of T. barbata. These stressors should be considered when developing plans to implement effective large-scale restoration of canopy-forming macroalgae

Accounting for inventory data and methodological choice uncertainty in a comparative life cycle assessment: the case of integrated multi-trophic aquaculture in an offshore Mediterranean enterprise

Purpose: Integrated multi-trophic aquaculture (IMTA), growing different species in the same space, is a technology that may help manage the environmental impacts of coastal aquaculture. Nutrient discharges to seawater from monoculture aquaculture are conceptually minimized in IMTA, while expanding the farm economic base. In this study, we investigate the environmental trade-offs for a small-to-medium enterprise (SME) considering a shift from monoculture towards IMTA production of marine fish. Methods: A comparative life cycle assessment (LCA), including uncertainty analysis, was implemented for an aquaculture SME in Italy. Quantification and simultaneous propagation of uncertainty of inventory data and uncertainty due to the choice of allocation method were combined with dependent sampling to account for relative uncertainties and statistical testing and interpretation to understand the uncertainty analysis results. Monte Carlo simulations were used as a propagation method. The environmental impacts per kilo of fish produced in monoculture and in IMTA were compared. Twelve impact categories were considered. The comparison is first made excluding uncertainty (deterministic LCA) and then accounting for uncertainties. Results and discussion: Deterministic LCA results evidence marginal differences between the impacts of IMTA and monoculture fish production. IMTA performs better on all impacts studied. However, statistical testing and interpretation of the uncertainty analysis results showed that only mean impacts for climate change are significantly different for both productive systems, favoring IMTA. For the case study, technical variables such as scales of production of the species from different trophic levels, their integration (space and time), and the choice of species determine the trade-offs. Also, LCA methodological choices such as that for an allocation method and the treatment of relative uncertainties were determinant in the comparison of environmental trade-offs. Conclusions: The case study showed that environmental trade-offs between monoculture and IMTA fish production depend on technical variables and methodological choices. The combination of statistical methods to quantify, propagate, and interpret uncertainty was successfully tested. This approach supports more robust environmental trade-off assessments between alternatives in LCAs with uncertainty analysis by adding information on the significance of results. It was difficult to establish whether IMTA does bring benefits given the scales of production in the case study. We recommend that the methodology defined here is applied to fully industrialized IMTA systems or bay-scale environments, to provide more robust conclusions about the environmental benefits of this aquaculture type in Europe

Spatial variation in key functional traits of Mediterranean fucoid algae: Insights from Cystoseira sensu lato intertidal canopies

Cystoseira sensu lato are fucoid algae that form dense stands on intertidal and subtidal rocky reefs sustaining species-rich associated assemblages. The increasing human pressure is causing the decline of these marine forests, raising wide concerns on the ecological consequences of their loss. Yet, little is known about functional trait variables of Cystoseira s.l. species, which are essential to a deeper understanding of their contribution to the functioning of coastal ecosystems. We analysed the intraspecific spatial variation of the total organic matter, Corg, N and P contents in Ericaria amentacea from intertidal rocky shores in the W Mediterranean Sea. Specifically, we quantified spatial patterns of variation of traits at large (100s km), small (1000s m), and local (100s cm) scale. We also explored potential interspecific variation by comparing the combined functional profile of trait variables between E. amentacea and Cystoseira compressa, an often co-occurring or vicariant species. Tissue contents of organic matter, Corg, N and P, were consistent among E. amentacea stands, supporting the hypothesis of a largescale (100s km) spatial homogeneity of such key traits in this species. Overlapping functional profiles between E. amentacea and C. compressa also suggested putative interspecific trait congruencies. However, a small-scale (1000s m) significant variability was found for all trait variables in E. amentacea. Variance components at small (1000s m) and local (100s cm) scale accounted for the largest contribution to the total spatial variation for all traits, recommending caution in the use of small and local-scale trait values to generalize functional performances of Cystoseira s.l. forests over large areas. This study represents one of the first attempts to shed light on the variability of key functional attributes of Cystoseira s.l. species at a range of spatial scales, which could assist more reliable assessments of their functional role and improve their management and conservation

Experimenting with ecosystem interaction networks in search of threshold potentials in real-world marine ecosystems

Thresholds profoundly affect our understanding and management of ecosystem dynamics, but we have yet to develop practical techniques to assess the risk that thresholds will be crossed. Combining ecological knowledge of critical system interdependencies with a large-scale experiment, we tested for breaks in the ecosystem interaction network to identify threshold potential in real-world ecosystem dynamics. Our experiment with the bivalves Macomona liliana and Austrovenus stutchburyi on marine sandflats in New Zealand demonstrated that reductions in incident sunlight changed the interaction network between sediment biogeochemical fluxes, productivity, and macrofauna. By demonstrating loss of positive feedbacks and changes in the architecture of the network, we provide mechanistic evidence that stressors lead to break points in dynamics, which theory predicts predispose a system to a critical transition