Prvo izvješće o epizoičnoj crvenoj algi Polysiphonia carettia (Hollenberg, 1971) na glavatoj želvi Caretta caretta u Jadranskom moru

The authors report the first record of the red alga Polysiphonia carettia (Hollenberg, 1971) in the Adriatic Sea, collected from two loggerhead sea turtles Caretta caretta captured along the coast of the Savudrija peninsula (Croatia, Northern Adriatic Sea). The identification of the samples is based on both vegetative and reproductive tetrasporangial features. The morphological characters of the specimens studied are in agreement with previous reports of this species from other parts of the Mediterranean Sea.Autori navode prvi zapis o pojavljivanju crvene alge Polysiphonia carettia (Hollenberg, 1971) u Jadranskom moru. Podaci su prikupljeni s dvije glavate želve Caretta caretta koje su primijećene uz obalu poluotoka Savudrija (Hrvatska, Sjeverni Jadran). Identifikacija uzoraka temeljila se na vegetativnim i na reproduktivnim tetrasporangijalnim značajkama. Morfološke značajke jedinki istraživane su u skladu s prethodnim izvješćima o ovoj vrsti iz drugih dijelova Sredozemnog mora

Spring composition of the macroalgal vegetation of a small offshore island in the north-western Mediterranean (Gallinara Island, Ligurian Sea)

Gallinara Island, a small island located 1.5 km off the shore of Liguria (Italy, north-western Mediterranean Sea) was included in a list of proposed Marine Protected Areas (MPA) in the early 90s. Since then, its benthic assemblages have been studied in detail and the main macrophytic communities have been mapped. A detailed assessment of its benthic macroalgal flora, however, has never been made. Gallinara was visited in the course of 5 consecutive years and its macroalgal flora was studied based on collections made by snorkelling and SCUBA diving. Overall, 141 macroalgal taxa were collected and identified (23 Chlorophyta, 94 Rhodophyta, 24 Ochrophyta); 91 of them represent new records for the island. One of the most notable new records is the non-indigenous red alga Womersleyella setacea, previously unreported from the island and widely distributed, particularly on the south-eastern shore. Observations made in the course of the surveys confirm the rarefaction of some large-sized brown algae (particularly Sargassum vulgare) but indicate also that others previously reported as rare (Cystoseira compressa, Dictyopteris polypodioides) are still common on the island

Macroalgal forest restoration: the effect of the foundation species

IntroductionActive restoration is the strategy needed to trigger or accelerate the recovery of degraded marine habitats, which provide the goods and services essential for preserving biodiversity and human wellbeing. Ecosystem engineers are generally the target species in the ecological restoration of marine ecosystems, and large-sized brown macroalgae (e.g., the Cystoseira complex) are a priority due to their crucial ecological importance and vulnerability in many regions of the Mediterranean Sea. MethodsHere, we present the results of a successful intervention of ecological restoration of Gongolaria barbata. Results and DiscussionOne year after the restoration intervention, we observed the recovery of the canopy in terms of ca. 15m2 with a significant increase in faunal abundance and biodiversity compared with reference areas. However, despite the high restored macroalgal growth rates, the assemblage structure was still significantly different from that of reference pristine areas. Despite the fast faunal colonization of a new 3D habitat linked to the successful re-introduction of the ecosystem engineers (i.e., macroalgae), the complete restoration of the properties of a habitat can be a much longer process. We conclude that, after 1 year, active restoration of macroalgal forests still results in a partial recovery of ecosystem functions (i.e., rehabilitation) rather than a full ecosystem restoration, thus stressing the need for long-term monitoring of restoration interventions

Ecological impacts of invading seaweeds: A meta-analysis of their effects at different trophic levels

Aim Biological invasions are among the main threats to biodiversity. To promote a mechanistic understanding of the ecological impacts of non-native seaweeds, we assessed how effects on resident organisms vary according to their trophic level. Location Global. Methods We performed meta-analytical comparisons of the effects of non-native seaweeds on both individual species and communities. We compared the results of analyses performed on the whole dataset with those obtained from experimental data only and, when possible, between rocky and soft bottoms. Results Meta-analyses of data from 100 papers revealed consistent negative effects of non-native seaweeds across variables describing resident primary producer communities. In contrast, negative effects of seaweeds on consumers emerged only on their biomass and, limited to rocky bottoms, diversity. At the species level, negative effects were consistent across primary producers' response variables, while only the survival of consumers other than herbivores or predators (e.g. deposit/suspension feeders or detritivores) decreased due to invasion. Excluding mensurative data, negative effects of seaweeds persisted only on resident macroalgal communities and consumer species survival, while switched to positive on the diversity of rocky-bottom consumers. However, negative effects emerged for biomass and, in rocky habitats, density of consumers other than herbivores or predators. Main conclusions Our results support the hypothesis that seaweeds' effects on resident biodiversity are generally more negative within the same trophic level than on higher trophic guilds. Finer trophic grouping of resident organisms revealed more complex impacts than previously detected. High heterogeneity in the responses of some consumer guilds suggests that impacts of non-native seaweeds at higher trophic levels may be more invader- and species-specific than competitive effects at the same trophic level. Features of invaded habitats may further increase variability in seaweeds' impacts. More experimental data on consumers' response to invasion are needed to disentangle the effects of non-native seaweeds from those of other environmental stressors

NAMBER: A biotic index for assessing the ecological quality of mesophotic biogenic reefs in the northern Adriatic Sea

1. The aim of the present study was to propose a biotic index (North Adriatic Mesophotic BiogEnic Reefs, NAMBER) suitable for assessing the ecological quality of the mesophotic biogenic reefs of the northern Adriatic continental shelf based on photographic sampling. 2. At each of the 20 study sites, the degree of bioconstruction (expressed as percentage cover of crustose coralline algae), the α-diversity (expressed as the mean number of taxa), and the degree of sensitivity to human disturbance and climate change (based on literature data and expert judgement) of the benthic assemblages were selected as descriptors and combined in the NAMBER index, using the best values that the three metrics can currently achieve in the studied region as a reference. 3. The study highlighted that there was large spatial heterogeneity among reefs and high variability in the ecological quality values obtained by NAMBER, ranging from bad to high. The index indicates that reefs lying furthest from the coast, under substantially lower anthropogenic pressure, have a generally higher status of environmental quality. However, a clear geographical pattern did not emerge, as reefs close together often had different ecological qualities. 4. The NAMBER index, which combines three ecological descriptors, in accordance with the requirements of the European Marine Strategy Framework Directive, represents a specific adaptation to the northern Adriatic Sea of a multimetric index previously developed for the north-western Mediterranean Sea, capitalizing on previous knowledge and research efforts. 5. This multimetric biotic index provides an effective standardized tool for monitoring programmes and environmental impact assessments in the northern Adriatic mesophotic biogenic reefs and lays the foundation for ecosystem-based management and conservation in this basin

Project “Biodiversity MARE Tricase”: A Species Inventory of the Coastal Area of Southeastern Salento (Ionian Sea, Italy)

Biodiversity is a broad concept that encompasses the diversity of nature, from the genetic to the habitat scale, and ensures the proper functioning of ecosystems. The Mediterranean Sea, one of the world’s most biodiverse marine basins, faces major threats, such as overexploitation of resources, pollution and climate change. Here we provide the first multi-taxa inventory of marine organisms and coastal terrestrial flora recorded in southeastern Salento (Ionian Sea, Italy), realized during the project “Biodiversity MARE Tricase”, which provided the first baseline of species living in the area. Sampling was carried out by SCUBA and free diving, fishing gears, and citizen science from 0 to 70 m. Overall, 697 taxa were found between March 2016 and October 2017, 94% of which were identified to the species level. Of these, 19 taxa represented new records for the Ionian Sea (36 additional new records had been reported in previous publications on specific groups, namely Porifera and Mollusca Heterobranchia), and two findings represented the easternmost records in the Mediterranean Sea (Helicosalpa virgula and Lampea pancerina). For eight other taxa, our findings represented the only locality in the Ionian Sea, besides the Straits of Messina. In addition to the species list, phenological events (e.g., blooms, presence of reproductive traits and behaviour) were also reported, with a focus on gelatinous plankton. Our results reveal that even for a relatively well-known area, current biodiversity knowledge may still be limited, and targeted investigations are needed to fill the gaps. Further research is needed to understand the distribution and temporal trends of Mediterranean biodiversity and to provide baseline data to identify ongoing and future changes

Spatial patterns and drivers of benthic community structure on the northern Adriatic biogenic reefs

The northern Adriatic Sea (NAS) hosts numerous biogenic subtidal reefs that are considered biodiversity hotspots. Several studies have already investigated the origin and biodiversity of these reefs. However, many of them are still unexplored and further knowledge is needed for their conservation. Here, the spatial variability, epibenthic community structure, and environmental features that characterize these habitats were investigated. Fifteen randomly selected reefs were sampled between 2013 and 2017, including some remote sites that have never been studied before. A fuzzy k-means clustering method and redundancy analysis were used to find similarities among sites in terms of epibenthic assemblages and to model relationships with abiotic variables. The results showed that these reefs are highly heterogeneous in terms of species composition and geomorphological features. The results were also consistent with previous studies and highlighted three main types of benthic assemblages defined by the dominance of different organisms, mainly reflecting the coastal-offshore gradient: nearshore reefs, generally dominated by stress-tolerant species; reefs at a middle distance from the coast, characterized by sponges, non-calcareous encrusting algae and ascidians; offshore reefs, dominated by reef builders. However, distance from the coast was not the only factor affecting species distribution, as other local factors and environmental characteristics also played a role. This kind of biogenic reefs in temperate seas are still poorly known. The present work contributed to shed further light on these habitats, by complementing the results of previous studies on their natural diversity, highlighting the specificity of the epibenthic communities of NAS reefs and the need to improve current, still inadequate, conservation measures