Simone Montano

A phylogeny reconstruction of the Dendrophylliidae (Cnidaria, Scleractinia) based on molecular and micromorphological criteria, and its ecological implications

Recent molecular phylogenetic studies have shown that most traditional families of zooxanthellate shallow‐water scleractinians are polyphyletic, whereas most families mainly composed of deep‐sea and azooxanthellate species are monophyletic. In this context, the family Dendrophylliidae (Cnidaria, Scleractinia) has unique features. It shows a remarkable variation of morphological and ecological traits by including species that are either colonial or solitary, zooxanthellate or azooxanthellate, and inhabiting shallow or deep water. Despite this morphological heterogeneity, recent molecular works have confirmed that this family is monophyletic. Nevertheless, what so far is known about the evolutionary relationships within this family, is predominantly based on skeleton macromorphology, while most of its species have remained unstudied from a molecular point of view. Therefore, we analysed 11 dendrophylliid genera, four of which were investigated for the first time, and 30 species at molecular, micromorphological and microstructural levels. We present a robust molecular phylogeny reconstruction based on two mitochondrial markers (COI and the intergenic spacer between COI and 16S) and one nuclear (rDNA), which is used as basis to compare micromorphogical and microstructural character states within the family. The monophyly of the Dendrophylliidae is well supported by molecular data and also by the presence of rapid accretion deposits, which are ca. 5 μm in diameter and arranged in irregular clusters, and fibres that thicken the skeleton organized in small patches of a few micrometres in diameter. However, all genera represented by at least two species are not monophyletic, Tubastraea excluded. They were defined by traditional macromorphological characters that appear affected by convergence, homoplasy and intraspecific variation. Micromorphogical and microstructural analyses do not support the distinction of clades, with the exception of the organization of thickening deposits for the Tubastraea clade.

Global-scale relationships between colonization ability and range size in marine and freshwater fish

Although fish range sizes are expected to be associated with species dispersal ability, several studies failed to find a clear relationship between range size and duration of larval stage as a measure of dispersal potential. We investigated how six characteristics of the adult phase of fishes (maximum body length, growth rate, age at first maturity, life span, trophic level and frequency of occurrence) possibly associated with colonization ability correlate with range size in both freshwater and marine species at global scale. We used more than 12 million point records to estimate range size of 1829 freshwater species and 10068 marine species. As measures of range size we used both area of occupancy and extent of occurrence. Relationships between range size and species traits were assessed using Canonical Correlation Analysis. We found that frequency of occurrence and maximum body length had a strong influence on range size measures, which is consistent with patterns previously found (at smaller scales) in several other taxa. Freshwater and marine fishes showed striking similarities, suggesting the existence of common mechanisms regulating fish biogeography in the marine and freshwater realms.

Mushroom corals as newly recorded hosts of the hydrozoan symbiont Zanclea sp.

Abstract Mushroom corals (Anthozoa: Scleractinia: Fungiidae) have been well documented as hosts of a rich associated fauna, but no records involving the symbiotic hydrozoan genus Zanclea (Hydrozoa: Capitata: Zancleidae) are known. These small (~1 mm long), coral-associated hydroids have only been reported from associations involving 23 non-fungiid scleractinian host species in the Indo-Pacific. Since both groups, Fungiidae and coral-dwelling Zanclea hydroids, are known to occur on Indo-Pacific coral reefs, it was unclear why no mushroom coral hosts were known. Therefore, a survey in the Maldives was performed aiming at the discovery of Zanclea–Fungiidae associations. Subsequently, 10 new host species were discovered and the number of recorded coral host genera increased from 17 to 24, taking recent taxonomic revisions into account. These findings indicate that the coral-associated biodiversity is still insufficiently explored.

First report of coral diseases in the Republic of Maldives

Little is known about coral diseases in the Indian Ocean region, especially in the Republic of Maldives. This study aimed at documenting the presence of coral diseases in the archipelago of the Maldives. Surveys for lesions in scleractinians conducted at 8 sites around Magoodhoo Island (Faafu Atoll) in October and November 2010 led to the identification of 5 coral diseases and 1 anomalous pigmentation response affecting 8 hard coral genera. White syndrome, skeleton-eroding band disease, black band disease, and Porites dark discoloration response were the most commonly observed conditions. In contrast with several reports of other reef systems, the overall observed prevalence of coral diseases was rather low (<2%), with individual prevalence ranging from 0.7% for skeleton-eroding band to 0.18% for Porites dark discoloration response. These data represent the first report of coral diseases for the Republic of Maldives.

New insights into the symbiosis between zanclea (cnidaria, hydrozoa) and scleractinians

Hydroids in the genus Zanclea are a recently discovered component of the fauna associated with reef‐building corals. The phylogenetic relationships among these species are not well known. The present work is based on field surveys in the Republic of Maldives, and for the first time, morphological and molecular analyses are integrated to distinguish a new hydroid species and provide new information on the ecology of this symbiosis. This new hydroid, Zanclea gallii sp. n., was associated with the scleractinian Acropora muricata; it was living sympatrically with its congener Zanclea sango, which was observed for the first time at this locality on the new scleractinian host Pavona varians. The relationships between these two hydroids and other available scleractinian‐associated Zanclea were investigated using two molecular markers, nuclear 28S rDNA and mitochondrial 16S rRNA. Zanclea gallii sp. n. and Z. sango were recovered as distinct lineages within a monophyletic group of scleractinian‐associated Zanclea based on both molecular and morphological data. All Zanclea species that were observed living in association with scleractinians belong to the ‘polymorpha group’ and share the morphological characteristic ‘polymorphic colony’. The genus Leptoseris is the 16th host coral identified for Zanclea. Compared with the frequency of the Z. gallii sp. n. association with A. muricata and Z. sango with the scleractinian P. varians, the latter is twice as common; however, the former exhibited higher Zanclea polyps concentrations over the colony surface. Overall, the Zanclea survey indicates that these diminutive hydroids are more commonly associated with coral than previously known.

Zanclea–coral association: new records from Maldives

To date, few hydroids have been observed to be associated with anthozoans, and only three Pacific Zanclea species are known to live in symbiosis with scleractinian corals, namely Zanclea gilii, Z. margaritae, and Z. sango (Boero et al. 2000; Pantos and Bythell 2010; Hirose and Hirose 2011). Here, we report the first evidence of this kind of association in the Indian Ocean. During recent expeditions to Magoodhoo Island (3 04¢N; 72 57¢E, Faafu Atoll, Republic of Maldives), numerous Zanclea spp. colonies wereobserved to live in symbiosis with scleractinians up to about 10 m depth. Specimens belonging to Zanclea spp. were found not only on Acropora muricata and Pavona sp., which are scleractinians previously known to be involved in this association, but also on coral colonies belonging to Favia favus, Favites halicora, Leptastrea purpurea, Montipora sp., Porites cylindrica, and Symphyllia sp. (Fig. 1a–f). Thus, our results extend the geographic distribution and the host range of this symbiosis, strongly suggesting that associations between hydroids and scleractinians could be much more widespread than previously thought, which is consistent with the scenarios depicted by recent molecular studies (Fontana et al. 2012). The benefits and costs of this symbiosis are still not clear. Although trophic and/or protection mutualism seems a plausible explanation of the relationship, a possible relationship between the occurrence of hydroids and coral diseases has also been proposed (Pantos and Bythell 2010). The potential implications of the hydroid–scleractinian symbiosis for coral health, its wide distribution, and the number of species it involves indicate urgent need for further investigations.

First record from the Atlantic: a Zanclea-scleractinian association at St. Eustatius, Dutch Caribbean

Scleractinian reef corals have been acknowledged as the most numerous host group for associated hydroids belonging to the genus Zanclea. To date, their geographical distribution is known to include several Indo-Pacific regions. During the Statia Marine Biodiversity Expedition to St. Eustatius (Lesser Antilles, Dutch Caribbean), the Zanclea-coral association was observed for the first time for the Caribbean Sea as well as for the Atlantic Ocean. Our findings confirm that the biodiversity associated with coral reefs remains insufficiently explored worldwide.

The Hidden Diversity of Zanclea Associated with Scleractinians Revealed by Molecular Data

Scleractinian reef corals have recently been acknowledged as the most numerous host group found in association with hydroids belonging to the Zanclea genus. However, knowledge of the molecular phylogenetic relationships among Zanclea species associated with scleractinians is just beginning. This study, using the nuclear 28S rDNA region and the fast-evolving mitochondrial 16S rRNA and COI genes, provides the most comprehensive phylogenetic reconstruction of the genus Zanclea with a particular focus on the genetic diversity among Zanclea specimens associated with 13 scleractinian genera. The monophyly of Zanclea associated with scleractinians was strongly supported in all nuclear and mitochondrial phylogenetic reconstructions. Furthermore, a combined mitochondrial 16S and COI phylogenetic tree revealed a multitude of hidden molecular lineages within this group (Clades I, II, III, V, VI, VII, and VIII), suggesting the existence of both host-generalist and genus-specific lineages of Zanclea associated with scleractinians. In addition to Z. gallii living in association with the genus Acropora, we discovered four well-supported lineages (Clades I, II, III, and VII), each one forming a strict association with a single scleractinian genus, including sequences of Zanclea associated with Montipora from two geographically separated areas (Maldives and Taiwan). Two host-generalist Zanclea lineages were also observed, and one of them was formed by Zanclea specimens symbiotic with seven scleractinian genera (Clade VIII). We also found that the COI gene allows the recognition of separated hidden lineages in agreement with the commonly recommended mitochondrial 16S as a DNA barcoding gene for Hydrozoa and shows reasonable potential for phylogenetic and evolutionary analyses in the genus Zanclea. Finally, as no DNA sequences are available for the majority of the nominal Zanclea species known, we note that they will be necessary to elucidate the diversity of the Zanclea-scleractinian association.

First record of coral-associated Zanclea (Hydrozoa, Zancleidae) from the Red Sea

Although corals are known to host a variety of marine organisms, to date few benthic hydrozoans have been observed to be associated with anthozoans. However, three species belonging to the genus Zanclea have recently been discovered that inhabit reef-building scleractinians. Here we report the first evidence of such Zanclea-coral associations from the Red Sea, extending their known geographical distributions and host range.

Exploring the effect of salinity changes on the levels of Hsp60 in the tropical coral Seriatopora caliendrum.

Osmotic stress represents a limiting physical parameter for marine organisms and especially for sessile scleractinian corals which are known to be basically stenohaline and osmoconformers. The salinity changes may cause important cellular damage since corals lack any developed physiological regulatory system. One mechanism of reaction to deleterious conditions is the rapid increase of the induction of heat shock proteins. This study highlights the modulation of the expression of a mitochondrial heat shock protein, such as the chaperonin Hsp60, in the animal tissues of the scleractinian coral Seriatopora caliendrum under three salinity scenarios (hypersalinity of 45 ppt, hyposalinity of 25 ppt and extreme hyposalinity of 15 ppt). The study was performed during the time course of a 2-day period and accompanied also by the assessment of the coral health condition. For each salinity stress S. caliendrum responds differently at the morphological and cellular levels, since the Hsp60 exhibited specific patterns of expression and the coral showed different tissue appearance. Furthermore, the response reflects the severity and exposure length of the disturbance. However, the results indicate that S. caliendrum seems able to tolerates high salinity better than low salinity. In particular, in extreme hyposalinity conditions, a considerable gradual down-regulation of Hsp60 was detected accompanied by necrosis and degradation of the coral tissues. The study suggests that Hsp60 may be involved in the mechanisms of cellular response to stress caused by exposure to adverse salinity.