Exploring the role of Micronesian islands in the maintenance of coral genetic diversity in the Pacific Ocean

Understanding how genetic diversity is maintained across patchy marine environments remains a fundamental problem in marine biology. The Coral Triangle, located in the Indo‐West Pacific, is the centre of marine biodiversity and has been proposed as an important source of genetic diversity for remote Pacific reefs. Several studies highlight Micronesia, a scattering of hundreds of small islands situated within the North Equatorial Counter Current, as a potentially important migration corridor. To test this hypothesis, we characterized the population genetic structure of two ecologically important congeneric species of reef‐building corals across greater Micronesia, from Palau to the Marshall Islands. Genetic divergences between islands followed an isolation‐by‐distance pattern, with Acropora hyacinthus exhibiting greater genetic divergences than A. digitifera, suggesting different migration capabilities or different effective population sizes for these closely related species. We inferred dispersal distance using a biophysical larval transport model, which explained an additional 15–21% of the observed genetic variation compared to between‐island geographical distance alone. For both species, genetic divergence accumulates and genetic diversity diminishes with distance from the Coral Triangle, supporting the hypothesis that Micronesian islands act as important stepping stones connecting the central Pacific with the species‐rich Coral Triangle. However, for A. hyacinthus, the species with lower genetic connectivity, immigration from the subequatorial Pacific begins to play a larger role in shaping diversity than input from the Coral Triangle. This work highlights the enormous dispersal potential of broadcast‐spawning corals and identifies the biological and physical drivers that influence coral genetic diversity on a regional scale.     

Comparative phylogeography of three codistributed stomatopods: origins and timing of regional lineage diversification in the Coral Triangle

The Indonesian-Australian Archipelago is the center of the world's marine biodiversity. Although many biogeographers have suggested that this region is a "center of origin," criticism of this theory has focused on the absence of processes promoting lineage diversification in the center. In this study we compare patterns of phylogeographic structure and gene flow in three codistributed, ecologically similar Indo-West Pacific stomatopod (mantis shrimp) species. All three taxa show evidence for limited gene flow across the Maluku Sea with deep genetic breaks between populations from Papua and Northern Indonesia, suggesting that limited water transport across the Maluku Sea may limit larval dispersal and gene flow across this region. All three taxa also show moderate to strong genetic structure between populations from Northern and Southern Indonesia, indicating limited gene flow across the Flores and Java Seas. Despite the similarities in phylogeographic structure, results indicate varied ages of the genetic discontinuities, ranging from the middle Pleistocene to the Pliocene. Concordance of genetic structure across multiple taxa combined with temporal discordance suggests that regional genetic structures have arisen from the action of common physical processes operating over extended time periods. The presence in all three species of both intraspecific genetic structure as well as deeply divergent lineages that likely represent cryptic species suggests that these processes may promote lineage diversification within the Indonesian-Australian Archipelago, providing a potential mechanism for the center of origin. Efforts to conserve biodiversity in the Coral Triangle should work to preserve both existing biodiversity as well as the processes creating the biodiversity.     

Multi‐locus sequence data reveal a new species of coral reef goby (Teleostei: Gobiidae: Eviota), and evidence of Pliocene vicariance across the Coral Triangle

Here, multi‐locus sequence data are coupled with observations of live colouration to recognize a new species, Eviota punyit from the Coral Triangle, Indian Ocean and Red Sea. Relaxed molecular clock divergence time estimation indicates a Pliocene origin for the new species, and the current distribution of the new species and its sister species Eviota sebreei supports a scenario of vicariance across the Indo‐Pacific Barrier, followed by subsequent range expansion and overlap in the Coral Triangle. These results are consistent with the ‘centre of overlap’ hypothesis, which states that the increased diversity in the Coral Triangle is due in part to the overlapping ranges of Indian Ocean and Pacific Ocean faunas. These findings are discussed in the context of other geminate pairs of coral reef fishes separated by the Indo‐Pacific Barrier.     

DNA barcoding of echinopluteus larvae uncovers cryptic diversity in neotropical echinoids

Surveys of larval diversity consistently increase biodiversity estimates when applied to poorly documented groups of marine invertebrates such as phoronids and hemichordates. However, it remains to be seen how helpful this approach is for detecting unsampled species in well‐studied groups. Echinoids represent a large, robust, well‐studied macrofauna, with low diversity and low incidence of cryptic species, making them an ideal test case for the efficacy of larval barcoding to discover diversity in such groups. We developed a reference dataset of DNA barcodes for the shallow‐water adult echinoids from both coasts of Panama and compared them to DNA sequences obtained from larvae collected primarily on the Caribbean coast of Panama. We sequenced mitochondrial cytochrome c oxidase subunit I (COI) for 43 species of adult sea urchins to expand the number and coverage of sequences available in GenBank. Sequences were successfully obtained for COI and 16S ribosomal DNA from 272 larvae and assigned to 17 operational taxonomic units (OTUs): 4 from the Pacific coast of Panama, where larvae were not sampled as intensively, and 13 from the Caribbean coast. Of these 17 OTUs, 13 were identified from comparisons with our adult sequences and belonged to species well documented in these regions. Another larva was identified from comparisons with unpublished sequences in the Barcode of Life Database (BOLD) as belonging to Pseudoboletia, a genus scarcely known in the Caribbean and previously unreported in Panama. Three OTUs remained unidentified. Based on larval morphology, at least two of these OTUs appeared to be spatangoids, which are difficult to collect and whose presence often goes undetected in standard surveys of benthic diversity. Despite its ability to capture unanticipated diversity, larval sampling failed to collect some species that are locally common along the Caribbean coast of Panama, such as Leodia sexiesperforata, Diadema antillarum, and Clypeaster rosaceus.     

Modeled connectivity of <Emphasis Type="Italic">Acropora millepora</Emphasis> populations from reefs of the Spratly Islands and the greater South China Sea

The Spratly Island archipelago is a remote network of coral reefs and islands in the South China Sea that is a likely source of coral larvae to the greater region, but about which little is known. Using a particle-tracking model driven by oceanographic data from the Coral Triangle region, we simulated both spring and fall spawning events of Acropora millepora, a common coral species, over a 46-yr period (1960–2005). Simulated population biology of A. millepora included the acquisition and loss of competency, settlement over appropriate benthic habitat, and mortality based on experimental data. The simulations aimed to provide insights into the connectivity of reefs within the Spratly Islands, the settlement of larvae on reefs of the greater South China Sea, and the potential dispersal range of reef organisms from the Spratly Islands. Results suggest that (1) the Spratly Islands may be a significant source of A. millepora larvae for the Palawan reefs (Philippines) and some of the most isolated reefs of the South China Sea; and (2) the relatively isolated western Spratly Islands have limited source reefs supplying them with larvae and fewer of their larvae successfully settling on other reefs. Examination of particle dispersal without biology (settlement and mortality) suggests that larval connectivity is possible throughout the South China Sea and into the Coral Triangle region. Strong differences in the spring versus fall larval connectivity and dispersal highlight the need for a greater understanding of spawning dynamics of the region. This study confirms that the Spratly Islands are likely an important source of larvae for the South China Sea and Coral Triangle region.     

The impact of ENSO on coral heat stress in the western equatorial Pacific

The Coral Triangle encompasses an extensive region of coral reefs in the western tropical Pacific with marine resources that support millions of people. As in all other reef regions, coral reefs in the Coral Triangle have been impacted by anomalously high ocean temperature. The vast majority of bleaching observations to date have been associated with the 1998 La Niña phase of ENSO. To understand the significance of ENSO and other climatic oscillations to heat stress in the Coral Triangle, we use a 5‐km resolution Regional Ocean Model System for the Coral Triangle (CT‐ROMS) to study ocean temperature thresholds and variability for the 1960–2007 historical period. Heat‐stress events are more frequent during La Niña events, but occur under all climatic conditions, reflecting an overall warming trend since the 1970s. Mean sea surface temperature (SST) in the region increased an average of ~ 0.1 °C per decade over the time period, but with considerable spatial variability. The spatial patterns of SST and heat stress across the Coral Triangle reflect the complex bathymetry and oceanography. The patterns did not change significantly over time or with shifts in ENSO. Several regions experienced little to no heat stress over the entire period. Of particular interest to marine conservation are regions where there are few records of coral bleaching despite the presence of significant heat stress, such as in the Banda Sea. Although this may be due to under‐reporting of bleaching events, it may also be due to physical factors such as mixing and cloudiness, or biological factors that reduce sensitivity to heat stress.     

The Mediterranean Sea as a ‘cul‐de‐sac’ for endemic fishes facing climate change

The Mediterranean Sea is a hotspot of biodiversity, and climate warming is expected to have a significant influence on its endemic fish species. However, no previous studies have predicted whether fish species will experience geographic range extensions or contractions as a consequence of warming. Here, we projected the potential future climatic niches of 75 Mediterranean Sea endemic fish species based on a global warming scenario implemented with the Mediterranean model OPAMED8 and a multimodel inference, which included uncertainty. By 2070–2099, the average surface temperature of the Mediterranean Sea was projected to warm by 3.1 °C. Projections for 2041–2060 are that 25 species would qualify for the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List, and six species would become extinct. By 2070–2099, 45 species were expected to qualify for the IUCN Red List whereas 14 were expected to become extinct. By the middle of the 21st century, the coldest areas of the Mediterranean Sea (Adriatic Sea and Gulf of Lion) would act as a refuge for cold‐water species, but by the end of the century, those areas were projected to become a ‘cul‐de‐sac’ that would drive those species towards extinction. In addition, the range size of endemic species was projected to undergo extensive fragmentation, which is a potentially aggravating factor. Since a majority of endemic fishes are specialists, regarding substratum and diet, we may expect a reduced ability to track projected climatic niches. As a whole, 25% of the Mediterranean Sea continental shelf was predicted to experience a total modification of endemic species assemblages by the end of the 21st century. This expected turnover rate could be mitigated by marine protected areas or accelerated by fishing pressure or competition from exotic fishes. It remains a challenge to predict how these assemblage modifications might affect ecosystem function.     

Status of Marine Biodiversity of the China Seas

China''s seas cover nearly 5 million square kilometers extending from the tropical to the temperate climate zones and bordering on 32,000 km of coastline, including islands. Comprehensive systematic study of the marine biodiversity within this region began in the early 1950s with the establishment of the Qingdao Marine Biological Laboratory of the Chinese Academy of Sciences. Since that time scientists have carried out intensive multidisciplinary research on marine life in the China seas and have recorded 22,629 species belonging to 46 phyla. The marine flora and fauna of the China seas are characterized by high biodiversity, including tropical and subtropical elements of the Indo-West Pacific warm-water fauna in the South and East China seas, and temperate elements of North Pacific temperate fauna mainly in the Yellow Sea. The southern South China Sea fauna is characterized by typical tropical elements paralleled with the Philippine-New Guinea-Indonesia Coral triangle typical tropical faunal center.This paper summarizes advances in studies of marine biodiversity in China''s seas and discusses current research mainly on characteristics and changes in marine biodiversity, including the monitoring, assessment, and conservation of endangered species and particularly the strengthening of effective management. Studies of (1) a tidal flat in a semi-enclosed embayment, (2) the impact of global climate change on a cold-water ecosystem, (3) coral reefs of Hainan Island and Xisha-Nansha atolls, (4) mangrove forests of the South China Sea, (5) a threatened seagrass field, and (6) an example of stock enhancement practices of the Chinese shrimp fishery are briefly introduced. Besides the overexploitation of living resources (more than 12.4 million tons yielded in 2007), the major threat to the biodiversity of the China seas is environmental deterioration (pollution, coastal construction), particularly in the brackish waters of estuarine environments, which are characterized by high productivity and represent spawning and nursery areas for several economically important species. In the long term, climate change is also a major threat. Finally, challenges in marine biodiversity studies are briefly discussed along with suggestions to strengthen the field. Since 2004, China has participated in the Census of Marine Life, through which advances in the study of zooplankton and zoobenthos biodiversity were finally summarized.     

Connectivity and the development of population genetic structure in Indo‐West Pacific coral reef communities

Aim To identify connectivity patterns among coral reefs of the Indo‐West Pacific. Projecting connectivity forward in time provides a framework for studying long‐term source–sink dynamics in the region, and makes it possible to evaluate the manner in which migration shapes population genetic structure at regional scales. This information is essential for addressing critical gaps in knowledge for conservation planning efforts in one of the most biologically diverse regions on earth. Location Coral reefs of the Indo‐West Pacific, ranging from 15° S to 30° N and 95° E to 140° E. Methods Individual‐based biophysical dispersal models were used in conjunction with matrix projection to identify the expected patterns of exchange between coral reefs over time. Results Present‐day oceanographic conditions lead to the transport of larvae from the South China Sea into the Coral Triangle region via the Sulu Sea, and from northern Papua New Guinea and the Solomon Islands via Halmahera. The directionality of the system leads to the expected accumulation of organisms from outlying areas into the Coral Triangle region over time, particularly in the vicinity of the Maluku Islands and eastern Sulawesi. Coral reefs in Papua New Guinea, the Sulu Archipelago and areas within the Philippines are expected to be areas of high diversity as well. Main conclusions Biophysical dispersal models, used in conjunction with matrix projection, provide an effective means of simulating connectivity structure across the Indo‐West Pacific and thereby evaluating the directionality of genetic diversity. Migration appears to have a significant influence on population genetic structure in the region. Based on present‐day ocean currents, coral reefs in the South China Sea, northern Papua New Guinea and the Solomon Islands are contributing to high levels of diversity in the Coral Triangle.     

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.     

Species richness of motile cryptofauna across a gradient of reef framework erosion

Coral reef ecosystems contain exceptionally high concentrations of marine biodiversity, potentially encompassing millions of species. Similar to tropical rainforests and their insects, the majority of reef animal species are small and cryptic, living in the cracks and crevices of structural taxa (trees and corals). Although the cryptofauna make up the majority of a reef??s metazoan biodiversity, we know little about their basic ecology. We sampled motile cryptofaunal communities from both live corals and dead carbonate reef framework across a gradient of increasing erosion on a reef in Pacific Panamá. A total of 289 Operational Taxonomic Units (OTUs) from six phyla were identified. We used species-accumulation models fitted to individual- and sample-based rarefaction curves, as well as seven nonparametric richness estimators to estimate species richness among the different framework types. All procedures predicted the same trends in species richness across the differing framework types. Estimated species richness was higher in dead framework (261?C370 OTUs) than in live coral substrates (112?C219 OTUs). Surprisingly, richness increased as framework structure was eroded: coral rubble contained the greatest number of species (227?C320 OTUs) and the lowest estimated richness of 47?C115 OTUs was found in the zone where the reef framework had the greatest vertical relief. This contradicts the paradigm that abundant live coral indicates the apex of reef diversity.     

The determinants of species richness of a relatively young coral-reef ichthyofauna

Aim Unique topographic features left the Red Sea and its north‐eastern extension into the Gulf of Aqaba practically devoid of coral‐reef‐based organisms during the last glacial maximum. The current ichthyofauna in these two ‘regions’ thus represents the product of relatively recent colonization by species found in the Arabian Sea, which adjoins the Red Sea at its southern tip. We used this system to test why some marine species seemingly fail to extend their geographic range, thereby generating spatial heterogeneity in biodiversity. Location The Arabian Sea, Red Sea, and the Gulf of Aqaba. Methods A list of coral‐reef‐associated fish species, belonging to the 10 most speciose families, was compiled for each region using published sources. The data were analysed (major axis regression, randomization tests) for taxonomic and body‐size‐dependent biases in colonization probabilities. A simple probabilistic model was used to examine the potential contribution of local (within‐region) extinctions to determining species composition in the Red Sea. Results Of the 462 reef‐associated species that inhabit the Arabian Sea, 69% have crossed successfully into the Red Sea; of these, 55% have crossed into the Gulf of Aqaba. A species’ probability of being found in either ‘target’ was independent of presumed innate differences, i.e. ecological correlates of taxonomic affiliation and body size. Similarly, local extinctions were found unlikely to have been of consequence over the past several thousand years. Main conclusions Present‐day differences in the species richness of reef‐associated fish species among the Arabian Sea, Red Sea and Gulf of Aqaba appear to be the product of external, non‐selective constraints on colonization. The random nature of the colonization process is suggestive of ecological redundancy among coral‐reef fish species. Importantly, the study places a time frame on the processes that determine spatial patterns of biodiversity in reef fish.     

Measuring conservation success with missing Marine Protected Area boundaries: A case study in the Coral Triangle

The on-going loss of biodiversity calls for assessing the performance of conservation strategies. In the case of marine protected areas (MPAs), a common indicator of success is the amount of biodiversity protected within them. However, there are many cases where the information for the official MPA boundary is not available, making it difficult to precisely measure the indicator. A solution to this problem is to create circular buffers around the centre location of MPAs for which boundaries are missing, equivalent in area to that reported officially for the MPA. The Coral Triangle Atlas provides the opportunity to quantify more precisely the validity of using buffers as proxies for MPA boundaries both at national and regional scales in the Coral Triangle. We used 612 existing MPA boundaries, converted them into point data at their centroids and then created circular buffers of area equal to that of the MPAs’ original polygons. Errors in estimated area of protected coral reefs were used to measure the bias created by the centroid buffers. We obtained an underestimation of protected coral reef area, both at the scale of the Coral Triangle region and at a national scale when using centroid buffers, with a larger underestimation as more MPA boundary proxies were used. We found that the size of MPA does not have a significant effect on the percentage of bias when MPAs are smaller than 100 km² at a national level, and smaller than 1000 km² at a regional level. With less than 15% of the total MPAs in the CT region larger than 100 km², these results suggest that using buffers at a national scale for small MPAs may be a good solution to missing boundaries and cheaper than trying to collect exact information if working at a national or multinational scale. However, for countries with large MPAs such as Indonesia, using this proxy system will tend to create a larger error. At a regional scale, such as the Coral Triangle region, an estimation of total protected coral reef using buffers as MPA boundaries proxies will produce a small underestimation, thus, producing conservative results of protected coral reef area. This study shows the importance of assessing the bias introduced by using proxies for MPA boundaries when measuring indicators of conservation target achievement for coastal and marine areas.     

Biogeography of pelagic bacterioplankton across an antagonistic temperature-salinity gradient in the Red Sea

The Red Sea is a unique marine ecosystem with contrasting gradients of temperature and salinity along its north-to-south axis. It is an extremely oligotrophic environment that is characterized by perpetual year-round water column stratification, high annual solar irradiation, and negligible riverine and precipitation inputs. In this study, we investigated whether the contemporary environmental conditions shape community assemblages by pyrosequencing 16S rRNA genes of bacteria in surface water samples collected from the northeastern half of this water body. A combined total of 1855 operational taxonomic units (OTUs) were recovered from the 'small-cell' and 'large-cell' fractions. Here, a few major OTUs affiliated with Cyanobacteria and Proteobacteria accounted for ～93% of all sequences, whereas a tail of 'rare' OTUs represented most of the diversity. OTUs allied to Surface 1a/b SAR11 clades and Prochlorococcus related to the high-light-adapted (HL2) ecotype were the most widespread and predominant sequence types. Interestingly, the frequency of taxa that are typically found in the upper mesopelagic zone was significantly elevated in the northern transects compared with those in the central, presumably as a direct effect of deep convective mixing in the Gulf of Aqaba and water exchange with the northern Red Sea. Although temperature was the best predictor of species richness across all major lineages, both spatial and environmental distances correlated strongly with phylogenetic distances. Our results suggest that the bacterial diversity of the Red Sea is as high as in other tropical seas and provide evidence for fundamental differences in the biogeography of pelagic communities between the northern and central regions.     

Ecological traits and environmental affinity explain Red Sea fish introduction into the Mediterranean

Alien species are considered one of the prime threats to biodiversity, driving major changes in ecosystem structure and function. Identifying the traits associated with alien introduction has been largely restricted to comparing indigenous and alien species or comparing alien species that differ in abundance or impact. However, a more complete understanding may emerge when the entire pool of potential alien species is used as a control, information that is rarely available. In the eastern Mediterranean, the marine environment is undergoing an unparalleled species composition transformation, as a flood of aliens have entered from the Red Sea following the opening of the Suez Canal in 1869. In this study, we compile data on species traits, geographical distribution, and environmental affinity of the entire pool of reef‐associated fish species in the Red Sea and more generally across the Indo‐Pacific. We use this extensive data to identify the prime characteristics separating Red Sea species that have become alien in the Mediterranean from those that have not. We find that alien species occupy a larger range of environments in their native ranges, explaining their ability to colonize the seasonal Mediterranean. Red Sea species that naturally experience high maximum temperatures in their native range have a high probability of becoming alien. Thus, contrary to predictions of an accelerating number of aliens following increased water temperatures, hotter summers in this region may prevent the establishment of many alien species. We further find that ecological trait diversity of alien species is substantially more evenly spaced and more divergent than random samples from the pool of Red Sea species, pointing at additional processes, such as competition, promoting ecological diversity among alien species. We use these results to provide a first quantitative ranking of the potential of Red Sea species to become established in the eastern Mediterranean.     

Role of DNA barcoding in marine biodiversity assessment and conservation: An update

More than two third area of our planet is covered by oceans and assessment of marine biodiversity is a challenging task. With the increasing global population, there is a tendency to exploit marine resources for food, energy and other requirements. This puts pressure on the fragile marine environment and necessitates sustainable conservation efforts. Marine species identification using traditional taxonomical methods is often burdened with taxonomic controversies. Here we discuss the comparatively new concept of DNA barcoding and its significance in marine perspective. This molecular technique can be useful in the assessment of cryptic species which is widespread in marine environment and linking the different life cycle stages to the adult which is difficult to accomplish in the marine ecosystem. Other advantages of DNA barcoding include authentication and safety assessment of seafood, wildlife forensics, conservation genetics and detection of invasive alien species (IAS). Global DNA barcoding efforts in the marine habitat include MarBOL, CeDAMar, CMarZ, SHARK-BOL, etc. An overview on DNA barcoding of different marine groups ranging from the microbes to mammals is revealed. In conjugation with newer and faster techniques like high-throughput sequencing, DNA barcoding can serve as an effective modern tool in marine biodiversity assessment and conservation.     

High Meiofaunal and Nematodes Diversity around Mesophotic Coral Oases in the Mediterranean Sea

Although the mesophotic zone of the Mediterranean Sea has been poorly investigated, there is an increasing awareness about its ecological importance for its biodiversity, as fish nursery and for the recruitment of shallow water species. Along with coastal rocky cliffs, isolated coralligenous concretions emerging from muddy bottoms are typical structures of the Mediterranean Sea mesophotic zone. Coralligenous concretions at mesophotic depths in the South Tyrrhenian Sea were investigated to assess the role of these coralligenous oases in relation to the biodiversity of surrounding soft sediments. We show here that the complex structures of the coralligenous concretions at ca. 110 m depth influence the trophic conditions, the biodiversity and assemblage composition in the surrounding sediments even at considerable distances. Coral concretions not only represent deep oases of coral biodiversity but they also promote a higher biodiversity of the fauna inhabiting the surrounding soft sediments. Using the biodiversity of nematodes as a proxy of the total benthic biodiversity, a high turnover biodiversity within a 200 m distance from the coralligenous concretions was observed. Such turnover is even more evident when only rare taxa are considered and seems related to specific trophic conditions, which are influenced by the presence of the coralligenous structures. The presence of a high topographic complexity and the trophic enrichment make these habitats highly biodiverse, nowadays endangered by human activities (such as exploitation of commercial species such as Corallium rubrum, or trawling fisheries, which directly causes habitat destruction or indirectly causes modification in the sedimentation and re-suspension rates). We stress that the protection of the coralligenous sea concretions is a priority for future conservation policies at the scale of large marine ecosystems and that a complete census of these mesophotic oases of biodiversity should be a priority for future investigations in the Mediterranean Sea.     

Abundance and composition of epiphytic bacterial and archaeal ammonia oxidizers of marine red and brown macroalgae

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are important for nitrogen cycling in marine ecosystems. Little is known about the diversity and abundance of these organisms on the surface of marine macroalgae, despite the algae's potential importance to create surfaces and local oxygen-rich environments supporting ammonia oxidation at depths with low dissolved oxygen levels. We determined the abundance and composition of the epiphytic bacterial and archaeal ammonia-oxidizing communities on three species of macroalgae, Osmundaria volubilis, Phyllophora crispa, and Laminaria rodriguezii, from the Balearic Islands (western Mediterranean Sea). Quantitative PCR of bacterial and archaeal 16S rRNA and amoA genes was performed. In contrast to what has been shown for most other marine environments, the macroalgae's surfaces were dominated by bacterial amoA genes rather than those from the archaeal counterpart. On the basis of the sequences retrieved from AOB and AOA amoA gene clone libraries from each algal species, the bacterial ammonia-oxidizing communities were related to Nitrosospira spp. and to Nitrosomonas europaea and only 6 out of 15 operational taxonomic units (OTUs) were specific for the host species. Conversely, the AOA diversity was higher (43 OTUs) and algal species specific, with 17 OTUs specific for L. rodriguezii, 3 for O. volubilis, and 9 for P. crispa. Altogether, the results suggest that marine macroalgae may exert an ecological niche for AOB in marine environments, potentially through specific microbe-host interactions.     

Description of ten new Lobophora species from the Bismarck Sea (Papua New Guinea)

Sampling in the framework of the research program called ‘La Planète Revisitée’ in Kavieng and Madang (Papua New Guinea) brought thus far unknown diversity of the brown algal genus Lobophora to the surface. DNA‐assisted alpha taxonomy allowed identifying the presence of 16 species Lobophora from these two localities, which only share four species in common. Ten species are newly described, including four, which are only known to the Bismarck Sea. A more exhaustive sampling across the Bismarck Sea, and more largely across the Coral Triangle, will very likely unveil an even greater diversity. The present study underscores the fragmentary nature of our knowledge of macroalgal diversity in this region.