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A worldwide increase in the prevalence of coral diseases and mortality has been linked to ocean warming due to changes in coral-associated bacterial communities, pathogen virulence, and immune system function. In the Mediterranean basin, the worrying upward temperature trend has already caused recurrent mass mortality events in recent decades. To evaluate how elevated seawater temperatures affect the immune response of a thermophilic coral species, colonies of Astroides calycularis were exposed to environmental (23 °C) or elevated (28 °C) temperatures, and subsequently challenged with bacterial lipopolysaccharides (LPS). Using immunolabeling with specific antibodies, we detected the production of Toll-like receptor 4 (TLR4) and nuclear factor kappa B (NF-kB), molecules involved in coral immune responses, and heat shock protein 70 (HSP70) activity, involved in general responses to thermal stress. A histological approach allowed us to characterize the tissue sites of activation (epithelium and/or gastroderm) under different experimental conditions. The activity patterns of the examined markers after 6 h of LPS stimulation revealed an up-modulation at environmental temperature. Under warmer conditions plus LPS-challenge, TLR4-NF-kB activation was almost completely suppressed, while constituent elevated values were recorded under thermal stress only. An HSP70 up-regulation appeared in both treatments at elevated temperature, with a significantly higher activation in LPS-challenge colonies. Such an approach is useful for further understanding the molecular pathogen-defense mechanisms in corals in order to disentangle the complex interactive effects on the health of these ecologically relevant organisms related to global climate change. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is warming sea water worldwide, pushing the limits of tolerance for marine organisms and driving a decline in biodiversity. The risk of thermal anomalies has increased particularly in the Mediterranean region over the last 30 yrs, where intense warming has been identified as one of the main stressors in coastal regions. To determine the influence of warmer conditions on the immunity of an endemic Mediterranean coral species, different immune activity parameters were compared in response to elevated temperature (~ 28 °C) and the presence of a pathogen-associated molecular pattern—Escherichia coli lipopolysaccharide (LPS)—as an elicitor of the innate immune response of Astroides calycularis. Immune parameters, which included phenoloxidase-like, glutathione peroxidase, lysozyme-like, alkaline phosphatase, and esterase enzyme activity, were measured over time after LPS balneation (0-, 12-, 48-, and 120 h time point). All five enzymes demonstrated constant values under environmental conditions (~ 23 °C), indicating a constituent activity. LPS at environmental temperature induced significant upregulation immediately after exposure (0 h-time point), demonstrating an immune response to the pathogen elicitor. Under warmer conditions (~ 28 °C), constituent values increased over time, indicating a shift in the immune strategy to maintain homeostasis. However, warmer sea water, within the summer range experienced by this coral species, impaired the immune response to LPS, delaying it over time. These changes in immune strategy indicate that temperature affects coral immunity and, in thermophilic A. calycularis, results in an energy trade-off that could maintain its health-state through suboptimal conditions during multiple perturbations, such as summertime diseases. [ABSTRACT FROM AUTHOR]

Brown foundation seaweeds are key elements increasing substrate heterogeneity and shaping the biodiversity in rocky coastal ecosystems. They are, however, vulnerable species that are declining due to multiple anthropogenic and climate change stressors, leading to a shift to less structural complex habitats. We investigate the role of structural attributes of two intertidal macroalgae, Ericaria amentacea and Laurencia obtusa, in shaping the abundance and diversity of their associated epifaunal assemblages. For this aim, we measured seaweeds' biomass, thallus volume and length (used here as proxy of substrate complexity), and explored which seaweeds' substrate attribute explained better variation of epifaunal assemblages. Results showed that E. amentacea was more complex than L. obtusa and hosted a higher number of epifaunal individuals. However, unlike that expected, the epifaunal assemblage of L. obtusa was more structured with higher Shannon–Wiener diversity and Pielous' evenness. Our findings indicate that, besides seaweed's substrate attributes, other mechanisms such as wave action and chemical defense might play a role in structuring epifaunal assemblages. We suggest that a shift from E. amentacea to L. obtusa population could have effect on structure and abundance of associated epifaunal assemblages. Certainly, further investigations are needed to clear up the consequences of these changes. [ABSTRACT FROM AUTHOR]

We present the first dataset of meiofauna associated with vermetid reefs (biogenic constructions of Mediterranean intertidal habitat) in two areas along the northern coast of Sicily, Italy. The vermetid reefs are characterized by a horizontal extension from the shore towards the open sea and can be divided into three zones (the inner margin, the cuvette zone and the outer margin) which differ in hydrodynamic features. We studied the spatial distribution of meiofauna along the horizontal axis of the vermetid reefs, investigating the communities inhabiting the sediment inside cuvettes (shallow pools inside the “cuvette zone”) located between the inner and the outer margins of the reefs. We observed an increase in meiofaunal abundance from the inner to the outer part of the reef (from 1808 ± 80 to 2992 ± 512 ind. 100 cm−2) in both areas. Moreover, we studied meiofaunal communities associated with the most abundant macroalgae (Cystoseira sp., Jania rubens, Palisada perforata, Dictyota sp. and Padina pavonica) living on the reefs, investigating the influence of habitat size (biomass) and identity (complexity) of macroalgae. We found that meiofauna varied in abundance (from 446 ± 51 to 1758 ± 231 ind. 100 cm−2 on P. perforata and Cystoseira sp., respectively), on different macroalgae, and that the habitat size significantly influenced these abundances, but its effect was dependent on macroalgal identity. In fact, we observed a positive correlation between meiofaunal abundance and algal complexity (fractal dimension). The high algal cover in the “cuvette zone” of the reefs could contribute to make this zone more suitable for meiofauna, in particular close to the outer margin where we found more complex macroalgae (i.e. Cystoseira sp.). These results confirm that vermetid reefs, with their structural complexity, may play an important role in structuring benthic fauna in intertidal habitats. [ABSTRACT FROM AUTHOR]

In the Mediterranean, the gastropodDendropoma cristatum(sin.D. petraeum(Monterosato, 1884)) is the primary builder of the vermetid reef, an intertidal bioconstruction of exceptional ecological importance. Despite awareness of the need for conservation of this key species, the biology ofD. cristatumremains poorly understood. The recruitment ofD. cristatumdeserves particular attention because the absence of a planktonic larval stage limits its dispersal ability. We examined the temporal pattern of recruitment during the breeding season ofD. cristatumfrom June to September in 2013. Specifically, we compared the two portions of the vermetid reef (i.e. the inner edge and the outer edge) at localities with different exposures to wave motion. The number of recruits peaked in July, when it was significantly higher in the outer than in the inner edge. No differences emerged between localities with different wave exposures; however, the width of the reef was significantly related to the exposure index. Although there are still several gaps in our knowledge of the recruitment dynamics ofD. cristatum, this study contributes to characterising recruitment rate variation at small spatial and temporal scales. [ABSTRACT FROM PUBLISHER]

The occurrence of the invasive seaweedCaulerpa taxifoliain the Straits of Messina (Italy) provides an excellent opportunity to examine the spatial and temporal patterns of abundance of the endemic Mediterranean sacoglossanOxynoe olivacea.Densities of this species were recorded in March, June and October 2000 on three different habitats: the underside of boulders (UNB), the upper side of boulders (UPB), and the surface of concrete blocks (CB). Results showed that in March,O. olivaceawas consistently more abundant on UNB whereas in June it was present exclusively on CB. The density ofO. olivaceawas similar in the three habitats in October. The hiding behaviour ofO. olivaceaand its seeming disappearance in March did not coincide with a decline of abundance of phylloids ofC. taxifolia.The results represent an important basis for further studies devoted to the investigation of abundance of these marine invertebrates, which has been traditionally thought of as unpredictable. [ABSTRACT FROM PUBLISHER]

Although there is a great deal of evidence to show that supplementary feeding by humans in terrestrial environments causes pronounced changes in the distribution and behaviour of wild animals, at present very little is known about the potential for such effects on marine fish. This study evaluated the consequences of feeding by snorkellers on fish assemblages in the no-take area of the Ustica Island marine protected area (MPA; western Mediterranean) by (1) determining if reef fish assemblage structure is affected in space and time by tourists feeding the fish; (2) assessing the effects of feeding on the abundance of the most common fish species; and (3) assessing the effects of feeding on the size structure of the two most numerically dominant ones. In particular, we hypothesised that both the abundance and the size structure of some fish species would increase at the study site following supplementary feeding, since the additional food provided by humans would make the site more appealing to them. Fish feeding influenced the fish assemblages within the Ustica MPA, and significant spatio-temporal changes occurred. While fish feeding appeared to have no effect on the ornate wrasseThalassoma pavo, there was a noticeable increase in the number ofOblada melanuraandEpinephelus marginatusin the impacted location after feeding. It is very likely that aggregations of fishes that evolve as a result of fish feeding by the public may have negative effects on local populations of fishes and invertebrates that make up their prey. Recreational use of coastal areas and MPAs is increasing elsewhere, making fish feeding a generalised human activity. Accurate information about its effect on the fish assemblage is essential to make responsible management decisions. [ABSTRACT FROM AUTHOR]

1. To better understand the role and importance of body size in hermaphroditic mating system theory, the mating behaviour of the shelled sacoglossanOxynoe olivaceawas studied. This simultaneous hermaphrodite exhibits bilateral and unilateral sperm transfer and thus it is particularly suitable for studies on hermaphrodite sexual conflict.2. In this study three hypotheses on body size were tested: thatO. olivaceapartner size has an effect on (i) mating mode choice, (ii) duration of mating modes, and (iii) choice of sexual role. Furthermore, we tested Charnov's hypothesis that inO. olivacea, like many simultaneous hermaphrodites, a sexual conflict exists and the male role is preferred.3. A laboratory experiment was done to test the aforementioned hypothesis and to observe the general mating behaviour ofO. olivacea. Pairs of similar (S) and different (D) sizes were considered for a total of five different treatments (S1, S2, S3, D1, D2).4. During the five copulatory treatmentsO. olivaceamated up to 93 times. Specifically, pairs of the same size mated with bilateral sperm transfer while unilateral copulation was common in pairs of slightly differing size. Contrary to predictions, animals of small body size started mating in the female role.O. olivaceashowed an active alternation of sexual roles and thus did not specialize in one particular sexual role.5. This study produced evidence of a relationship between mating mode and body size inO. olivaceaand highlighted the need for new studies on this simultaneously hermaphroditic species.Functional Ecology(2004)18, 899 –906 [ABSTRACT FROM AUTHOR]

The short-term response of Mediterranean upper infralittoral macroalgal species to experimental human trampling was investigated. Disturbances of six different intensities were applied within the integral reserve of the Ustica Island marine protected area (Italy, Mediterranean Sea). The dominant macroalgal species Cystoseira brachicarpa v. balearica and Dictyota mediterranea were strongly affected by human trampling. Higher levels of disturbance significantly affected both algal percentage cover and canopy at an increasing rate. Three months after trampling, for both variables it was highlighted that the algal recovery from disturbance was incomplete, being significantly different among trampling intensities. The current study revealed that in the short-term it was not possible to identify critical levels of trampling that are sustainable for this shallow community. [ABSTRACT FROM PUBLISHER]

Presents a study that investigated the composition and structure of molluscan assemblages between algal species in the Mediterranean Sea. Relationship between algal architecture and molluscan assemblage; Differences in the architectural attributes of the algal species; Examination of the abundance and diversity of the molluscan assemblage.

Mollusc assemblages of three concrete artificial reefs (ARs) in the Gulf of Castellammare were compared with those of two nearby natural reefs (NRs). The reefs were located in areas characterized by different degrees of water transparency, with average annual Secchi disk visibility ranging from clear (>20 m) to turbid waters (<6 m). In spring 1995, 28 samples of 400 cm2 were scraped off the reefs at depths of 16–22 m (20 from ARs; 8 from NRs), which yielded a total of 116 species and 1084 specimens of molluscs. The assemblage derived from a NR in clear water showed the highest diversity, species richness, and evenness, while the highest number of specimens and dominance values were observed at an AR in turbid water. The lowest values of diversity and species richness were found at ARs in turbid water and the lowest number of specimens at a NR in turbid water. Comparison of the five reefs showed significant differences in average number of species and in diversity values, while differences in the number of specimens were not significant. Factorial correspondence analysis showed a pattern that was strongly polarized along the first axis by the NR in clear water and by the AR in turbid water. The most distinctive feature was the dominance of Bittium latreillii at AR sites. Three years after deployment, mollusc assemblages of ARs in the Gulf remain entities that are distinct from those of nearby natural reefs. However, the potential of the assemblages in terms of density of individuals is comparable to that of natural reefs. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved. [ABSTRACT FROM PUBLISHER]