Keep It Simple: Improving the Ex Situ Culture of Cystoseira s.l. to Restore Macroalgal Forests.

Brown algae from genus Cystoseira s.l. form dense underwater forests that represent the most productive areas in the Mediterranean Sea. Due to the combined effects of global and local stressors such as climate change, urbanization, and herbivore outbreaks, there has been a severe decline in brown algal forests in the Mediterranean Sea. Natural recovery of depleted sites is unlikely due to the low dispersal capacity of these species, and efficient techniques to restore such habitats are needed. In this context, the aims of our study were (1) to improve and simplify the current ex situ laboratory protocol for the cultivation of Gongolaria barbata by testing the feasibility of some cost-effective and time-efficient techniques on two donor sites of G. barbata and (2) to evaluate the survival and growth of young thalli during the laboratory phase and during the most critical five months after out-planting. Specifically, the following ex situ cultivation methods were tested: (A) cultivation on clay tiles in mesocosms with culture water prepared by three different procedures (a) filtered seawater with a 0.22 µm filter membrane, (b) filtered seawater with a 0.7 µm filter membrane (GF), and (c) UV-sterilized water, and (B) cultivation on clay tiles in open laboratory systems. After two weeks, all thalli were fixed to plastic lantern net baskets suspended at a depth of 2 m in the coastal sea (hybrid method), and the algal success was monitored in relation to the different donor sites and cultivation protocol. The satisfactory results of this study indicate that UV-sterilized water is suitable for the cultivation of G. barbata in mesocosm, which significantly reduces the cost of the laboratory phase. This opens the possibility of numerous and frequent algal cultures during the reproductive period of the species. Additionally, if the young thalli remain in the lantern net baskets for an extended period of several months, they can grow significantly in the marine environment without being exposed to pressure from herbivorous fish.

A preliminary study of soft bottom benthic communities in an area affected by intense maritime traffic (Slovenian Sea, Northern Adriatic).

Maritime traffic and port activities pose several environmental and ecological problems in the marine environment. The purpose of this study was to provide baseline data for the future assessment of anthropogenic impacts related with port activities in Slovenian Sea (Northern Adriatic Sea). The macrobenthic communities near the port of Koper, as well as sites offshore were analysed. Results showed that the sites offshore were generally richer and more structured than sites inside the Port area. Those differences were explained partly by depth and sediment grain size. The ecological quality indicated by M-AMBI index resulted Good/High at all the sampling sites. However, the k-dominance curves indicated a disturbance at certain sites, in particular in the port channels. This work highlights the need for consistent monitoring programs to provide baseline data for future studies assessment of anthropogenic impacts.

Diversity of Molluscan Assemblage in Relation to Biotic and Abiotic Variables in Brown Algal Forests.

Canopy-forming macroalgae, mainly those belonging to the order Fucales, form the so-called brown algal forests, which are among the most productive assemblages in shallow coastal zones. Their vertical, branching canopies increase nearshore primary production, provide nursery areas for juvenile fish, and sustain understory assemblages of smaller algae and both sessile and vagile fauna. The majority of benthic invertebrates inhabiting these forests have larval stages that spend some time floating freely or swimming in the plankton. Therefore, canopy-forming macroalgae play an important role as species collectors related to larval supply and hydrodynamic processes. During the past several decades, brown algal forests have significantly reduced their extension and coverage in the Mediterranean basin, due to multiple interacting natural and anthropogenic pressures, with negative consequences also for the related fauna. The aim of this research was to examine how differences in macrophyte abundance and structure, as well as environmental variables, affect the associated molluscan communities in the shallow northern Adriatic Sea. Sampling sites with well-developed vegetation cover dominated by different canopy-forming species were selected in the shallow infralittoral belt of the northern Adriatic Sea in the spring-summer period of the years 2019 and 2020. Our results confirm the importance of algal forests for molluscan assemblage, with a total of 68 taxa of molluscs found associated with macrophytes. Gastropods showed the highest richness and abundance, followed by bivalves. Mollusc richness and diversity (in terms of biotic indices) were not related with the degree of development of canopy-forming species (in terms of total cover and total volume), nor with the ecological status of benthic macroalgae at different depths. On the contrary, the variability in molluscan taxa abundances was explained by some environmental variables, such as temperature, pH, light, and nitrates concentration.

Habitat heterogeneity: A confounding factor for the effect of pollutants on macrobenthic community in coastal waters.

Discrepancies were found between Ecological Status of sediments evaluated though the analysis of macrobenthic community and chemical analyses along a heavily trafficked and contaminated maritime seaway in Tyrrhenian Sea. Chemical analyses showed some sites highly contaminated by PAHs and metals with values exceeding thresholds for Good Chemical status and representing potential toxicological risk for benthic animals. Conversely, macrobenthic communities were highly rich and diverse, with Ecological Status (through M-AMBI) Good and High at each site. Sampling depth, total organic carbon, and total nitrogen were the major factors influencing biotic indices (AMBI, M-AMBI, S, H), even if concentrations of PAHs and metals (V, As, and Fe) contributed in explaining a part of indices variability. Habitat heterogeneity of sampled sites is likely acting as a confounding factor for two reasons: (1) high variability of environmental parameters leads to high richness and diversity, to which M-AMBI is sensitive, and (2) environmental parameters explained part of the variability of indices, together with contaminants. Our results suggested the importance of considering natural variability as a fundamental step of environmental impact assessment, for the correct interpretation of biotic indices.

Spatial and temporal distribution of trace elements in Padina pavonica from the northern Adriatic Sea.

Chemical pollution is a major environmental concern especially in coastal areas, having adverse impacts on marine organisms and ecosystem services. Macroalgae can accumulate trace elements, but available studies are restricted to a limited number of elements and species. The goal of this research was to assess, seasonally, the concentrations of 22 elements in the brown alga Padina pavonica from monitoring sampling sites in Slovenian waters. The concentration of most elements in thalli differed significantly between spring and autumn, with generally higher levels in autumn samples. However, it was not possible to correlate these concentrations with the ecological status of macroalgae. The maximum values set by European regulations for the potentially hazardous As, Cd and Hg in food and feed were never exceeded, while Pb concentrations were slightly higher. The results show that P. pavonica can act as an effective bioindicator of chemical pollution.

First Restoration Experiment for Gongolaria barbata in Slovenian Coastal Waters. What Can Go Wrong?

The global decline of brown algal forests along rocky coasts is causing an exceptional biodiversity loss. Regardless of conservation efforts, different techniques have been developed for large-scale restoration strategies in the Mediterranean Sea. In this study we tested ex situ pilot restoration of Gongolaria barbata (=Treptacantha barbata) for the first time in Slovenian coastal waters. Healthy apical fronds of the species were collected and the development of recruits on clay tiles was followed under laboratory conditions for 20 days. Despite the experimental difficulties experienced, especially due to the lack of antibiotics to prevent the growth of the biofilm, G. barbata recruits were outplanted in the sea on two concrete plates with 48 tiles each, protected by purpose-built cages to avoid grazing by herbivorous fish. The high survival rate of juveniles after four months in the field (89% of the tiles on the plate that was constantly protected) suggests that outplanting G. barbata is an operable approach for restoration efforts in the northern Adriatic Sea. Our first experiment in Slovenian coastal waters provides new information for the optimization of the best practices during the laboratory cultivation and addresses the early steps of restoration and introduction of young thalli in the natural environment.

The difficulty of disentangling natural from anthropogenic forcing factors makes the evaluation of ecological quality problematic: A case study from Adriatic lagoons.

The complex and dynamic nature of transitional ecosystems pose problems for the assessment of the Ecological Quality Status required by the European Water Framework Directive (WFD; 2000/60/EC). In six Adriatic lagoons, Ecological Quality Status was studied by comparing a biotic index based on macrophytes (MaQI), and three indices based on invertebrates (M-AMBI, M-bAMBI, and ISD). Ecological Status evaluated though MaQI and ISD resulted in quite degraded ecosystems (moderate/poor/bad), with only opportunistic algae and macrobenthic communities dominated by small size classes. Those results were supported by physico-chemical parameters, indicating high nutrients inputs, and anthropogenic pressures related with agriculture and fishery activities. Ecological Status obtained with M-AMBI and M-bAMBI was higher, with some sites reaching even the "good" status. The best response to anthropogenic pressures, in terms of a pressure index, was obtained by M-AMBI and M-bAMBI. Nevertheless, the response of used metrics (such as AMBI and bAMBI) to environmental variables not related to anthropogenic impact, and the high heterogeneity of physical-chemical conditions within lagoons, represent potential problems for the correct evaluation of Ecological Status of transitional waters. When different metrics give different responses it becomes a problem for managers who cannot easily make a decision on the remedial measures. The disagreement among indices arose because of the different response of biological elements to different stressors, and because the different indices based on macroinvertebrates focused on different aspects of the community, providing complementary information. So urge the need to find alternative approaches for a correct assessment of Ecological Status, with the combination of different biological elements, and considering the development of new indices (e.g. M-bAMBI) or refinement of the existing ones.

Species-Area Relationship (SAR) models as tools for estimating faunal biodiversity associated with habitat builder species in sensitive areas: the case of the Mediterranean stony coral (Cladocora caespitosa).

Biodiversity associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767) was investigated at three levels: "microscale", focused on macrobenthic invertebrates within colonies; "mesoscale", focused on epibenthic megafauna among colonies; "macroscale", focused on associated ichthyofauna. The aim was to quantify associated diversity in terms of species richness, testing the efficiency of colony size (surface covered by a single colony) for the "microscale", and colony density or total coral coverage for "meso-" and "macroscale" as predictors and the consistency of models based on Species-Area Relationship (SAR) for those estimations. At level of "microscale", colony size was a good predictor, with richness of invertebrates increasing with the increasing of surface covered by each colony of C. caespitosa, following Arrhenius model. At levels of "mesoscale" and "macroscale", richness of epibenthic megafauna and fish were not related neither to colony density nor total coral coverage, but to sampled area, and frequency-based estimates of richness were used. The importance of C. caespitosa varied according to the investigation level, with most of taxa richness detected at the level of "microscale".

When the levee breaks: Effects of flood on offshore water contamination and benthic community in the Mediterranean (Ionian Sea).

In the last few years extreme weather events, including changes to storm frequency and intensity, have increased across all continents. In this note we assessed, for the first time in the Mediterranean Sea, the impact of a violent storm and consequent flood on offshore water contamination and benthic community along the Calabrian coast (Ionian Sea). Three sites (at 500, 1000, and 2000 m off the coast) were sampled along three parallel transects in 2013, 2014 (before), and 2015 (after the flood). After the flood, metals (especially Al, CrVI, Ni, Cu, Zn) in the water column increased in concentration. The flood affected the structure of the benthic community, causing a decrease of diversity, the dominance of few opportunistic species, and the decrease of M-AMBI values.

The efficiency of Taxonomic Sufficiency for identification of spatial patterns at different scales in transitional waters.

Taxonomic Sufficiency (TS), the use of coarser taxonomic resolution in monitoring plans, has been receiving increasing attention in last years. A comprehensive dataset of macrobenthos from 18 Italian lagoons in a range of different latitude, typology, salinity and surface area, was analysed in order to test the efficiency of TS, in terms of correlation between patterns at level of species and patterns resulting from different levels of taxonomic aggregation. First, TS was applied on a range of univariate indices, providing complementary information on macrobenthic community, in order to test the efficiency, in a contest of different taxonomic composition, and different number of lower taxa belonging to the same higher taxon in each lagoon. Then, TS was applied on multivariate analyses, in order to test whether the efficiency changes between two different scales: local (comparison of sites nested within each lagoon) and regional (comparison among lagoons), and with different data transformation. The patterns resulting from univariate indices and multivariate analyses, at both local and regional scales, were retained till family level, despite the different levels of taxonomic composition and different number of lower taxa belonging to the same higher taxon of different lagoons. Nevertheless, the correlation values among matrices and the effect of data transformation differed between regional and local scales. Our results support the efficiency of TS until family level, but at the same time underline the need of scale- and region-specific baseline knowledge prior application of TS in lagoons.

Heavy metals, OCPs, PAHs, and PCDD/Fs contamination in surface sediments of a coastal lagoon (Valli di Comacchio, NW Adriatic, Italy): Long term trend (2002-2013) and effect on benthic community.

Surface sediments contamination (heavy metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans) and benthic community of the Valli di Comacchio, were analysed from 2002 to 2013. Along the studied period, most of analysed pollutants did not exceed thresholds for Good chemical status of sediments. In 2008, a peak of contamination was observed, with total PAHs and OCPs exceeding their threshold. Considering metals, Ni and Cr exceeded their thresholds, but not the background levels for the area, suggesting natural enrichment; conversely Pb exceeded background levels for the area in many samples, but it exceeded its sediment quality thresholds only in few samples (2006, 2009, 2011). Conversely, the ecological status evaluated though AMBI and M-AMBI, was below the Good/Moderated thresholds established by WFD in most of the studied years. In the 11 yrs-study period, the benthic community showed a very weak response to chemical contamination.

Long-term variability of macrobenthic community in a shallow coastal lagoon (Valli di Comacchio, northern Adriatic): Is community resistant to climate changes?

A time series data of macrobenthic invertebrates of Valli di Comacchio lagoon (northern Adriatic) from 1996 to 2015, was analysed using Biological Traits Analysis, structural indices, AMBI and M-AMBI indices, with a twofold aim to: firstly, test the resilience of the system, and, secondly, test the influence of climate changes, in terms of temperature and precipitation pattern, on macrobenthic dynamics. Along the studied period macrobenthic community showed marked fluctuations, in terms of richness, diversity, biological traits and ecological groups, which could be related with environmental instability of the lagoon. At the same time, a general tendency towards a deterioration of ecological condition of the lagoon was observed, with a general decrease in species richness, diversity, percentage of sensitive species, and a general increase in the proportion of the more opportunistic trait modalities, such as deposit feeders, burrowing, infaunal and short living animals. Increasing yearly temperature explained only a small part of the variability of macrobenthic community, in terms of biological traits and diversity indices, and this was likely due to the effect of natural fluctuations of environmental parameters and anthropogenic disturbance. Nevertheless, all metrics used are consistent in identifying the response of benthic community to a severe disturbance, likely related with the summer heatwave in 2003. Less marked signs of disturbance were observed also in relations to the thermal anomaly of 2012. Biological Traits Analysis combined with more classical structural and ecological indices, proved to be efficient in identifying temporal changes of the community. Our results suggest that the expected increase in frequency, magnitude and duration of heatwaves could pose serious threat to the resilience capacity of lagoonal macrobenthic community.

Comparison of benthic indices for the evaluation of ecological status of three Slovenian transitional water bodies (northern Adriatic).

Benthic indicators are important tools for the classification of coastal and transitional water bodies. The aim of the work was to assess for the first time the Environmental Status (ES) of Slovenian transitional waters, comparing the following biotic indices: richness, Shannon-Weaver diversity, AMBI, M-AMBI, BENTIX and BITS indices. A total of 13 stations were sampled with a Van Veen grab, in three ecosystems in the northern Adriatic. Samples were sieved and sorted, invertebrates identified and counted. The anthropogenic impact was estimated with professional judgement. Richness and diversity showed a good response to anthropogenic pressure. Conversely, indices based on sensitivity/tolerance groups did not showed a clear distinction between more and less impacted ecosystems. In particular BENTIX underestimated the ES, while with BITS there was a overestimation. The best evaluation was obtained with M-AMBI, because even if based on a sensitivity/tolerance approach, it considered also the structural aspect of the community.