Biogeography of Wood-Boring Crustaceans (Isopoda: Limnoriidae) Established in European Coastal Waters

Marine wood-borers of the Limnoriidae cause great destruction to wooden structures exposed in the marine environment. In this study we collated occurrence data obtained from field surveys, spanning over a period of 10 years, and from an extensive literature review. We aimed to determine which wood-boring limnoriid species are established in European coastal waters; to map their past and recent distribution in Europe in order to infer species range extension or contraction; to determine species environmental requirements using climatic envelopes. Of the six species of wood-boring Limnoria previously reported occurring in Europe, only Limnoria lignorum, L. quadripunctata and L. tripunctata are established in European coastal waters. L. carinata and L. tuberculata have uncertain established status, whereas L. borealis is not established in European waters. The species with the widest distribution in Europe is Limnoria lignorum, which is also the most tolerant species to a range of salinities. L. quadripunctata and L. tripunctata appear to be stenohaline. However, the present study shows that both L. quadripunctata and L. tripunctata are more widespread in Europe than previous reports suggested. Both species have been found occurring in Europe since they were described, and their increased distribution is probably the results of a range expansion. On the other hand L. lignorum appears to be retreating poleward with ocean warming. In certain areas (e.g. southern England, and southern Portugal), limnoriids appear to be very abundant and their activity is rivalling that of teredinids. Therefore, it is important to monitor the distribution and destructive activity of these organisms in Europe

Diversity, environmental requirements, and biogeography of bivalve wood-borers (Teredinidae) in European coastal waters

Background: Bivalve teredinids inflict great destruction to wooden maritime structures. Yet no comprehensive study was ever carried out on these organisms in European coastal waters. Thus, the aims of this study were to: investigate the diversity of teredinids in European coastal waters; map their past and recent distributions to detect range expansion or contraction; determine salinity-temperature (S-T) requirements of species; flag, for future monitoring, the species that pose the greatest hazard for wooden structures. Results: A total of nine teredinid species were found established in European coastal waters. Seven were considered cryptogenic, of unknown origin, and two were considered alien species. Teredo navalis and Nototeredo norvagica were the species with the widest distribution in European waters. Recently, T. navalis has been reported occurring further east in the Baltic Sea but it was not found at a number of sites on the Atlantic coast of southern Europe. The Atlantic lineage of Lyrodus pedicellatus was the dominant teredinid in the southern Atlantic coast of Europe. In the Mediterranean six teredinid species occurred in sympatry, whereas only three of these occurred in the Black Sea. The species that pose the greatest hazard to wooden maritime structures in European coastal areas are T. navalis and the two lineages of L. pedicellatus. Conclusions: Combined data from field surveys and from the literature made it possible to determine the diversity of established teredinid species and their past and recent distribution in Europe. The environmental requirements of species, determined using climatic envelopes, produced valuable information that assisted on the explanation of species distribution. In addition, the observed trends of species range extension or contraction in Teredo navalis and in the two lineages of Lyrodus pedicellatus seem to emphasise the importance of temperature and salinity as determinants of the distribution of teredinids, whereas their life history strategy seems to play an important role on competition. Teredo navalis and pedicellatus-like Lyrodus species should be monitored due to their destructive capability. The two alien species may expand further their distribution range in Europe, becoming invasive, and should also be monitored.This research was partially funded by Fundação para a Ciência e a Tecnologia, Portugal through a personal grant to LB (SFRH/BD/17915/2004)

Hydrological features above a Southern Ocean seamount inhibit larval dispersal and promote speciation: evidence from the bathyal mytilid Dacrydium alleni sp. nov. (Mytilidae: Bivalvia)

The Maud Rise seamount (65°07.80′S 2°39.60′E), a distinct habitat in the Southern Ocean, was studied during the ANDEEP-SYSTCO expedition in 2007–2008 to describe its unique benthic assemblage, characterised by higher biomass and lower diversity than other SO locations. Epibenthic sledge deployments during the expedition revealed exceptionally high abundances of the small bivalve genus Dacrydium with a total of 516 specimens collected from this seamount, resembling up to 1860 bivalve individuals per 1000 m−2. The Dacrydium specimens were examined for taxonomic identification, population and reproductive biology. Shell and soft part morphology as well as life history characteristics were compared with all known congeners for which data are available. Hinge dentition, prodissoconch size and adult gill structure are notably different, supporting classification as a separate species, herein formally described as Dacrydium alleni sp. nov. Dacrydium alleni sp. nov. produces lecithotrophic larvae, capable of long-distance dispersal, yet is apparently restricted to the Maud Rise area, supporting the hypothesis that larval dispersal at isolated seamounts may be constrained by hydrographic rather than biological features. In addition to providing insight into the benthic assemblage at Maud Rise, this work also summarises the current taxonomic status of the genus Dacrydium in the Southern Ocean

Effects of climate change on marine coastal ecosystems – A review to guide research and management

There is growing concern over climate models that project significant changes in the oceans, with consequences on marine biodiversity and human well-being. However, marine and coastal ecosystems respond differently to climate change-related stressors depending on the ecosystem, species composition and interactions, geomorphologic settings, and spatial distribution, but also on the presence of local stressors interacting cumulatively with climate change-related pressures. Our paper provides a comprehensive review of the current literature about the effects of climate-related pressures on marine and coastal ecosystems and how local stressors affect their resilience. Our work focuses on key marine and coastal ecosystems from three ecoregions: the Caribbean Sea (coral reefs, mangrove forests, seagrass beds), the Mediterranean Sea (the coral Cladocora caespitosa, maërl beds and seagrass beds) and the North-East Atlantic, which include kelp forests, maërl beds, salt marshes and seagrass beds. This review highlights the need for a more comprehensive, multi-species, and multi-stressors approach to predict better changes at the ecosystem and seascape levels of marine and coastal ecosystems. Nevertheless, there is enough evidence to argue that addressing locally key manageable stressors common to multiple ecosystems, such as nutrient enrichment, coastal development, hydrologic disturbances, anchoring or sedimentation, will reduce the identified adverse effects of climate change. This knowledge is critical for practical conservation actions and coastal and marine spatial management at the ecoregion scale and beyond

Characterisation of the enzyme transport path between shipworms and their bacterial symbionts.

BACKGROUND: Shipworms are marine xylophagus bivalve molluscs, which can live on a diet solely of wood due to their ability to produce plant cell wall-degrading enzymes. Bacterial carbohydrate-active enzymes (CAZymes), synthesised by endosymbionts living in specialised shipworm cells called bacteriocytes and located in the animal's gills, play an important role in wood digestion in shipworms. However, the main site of lignocellulose digestion within these wood-boring molluscs, which contains both endogenous lignocellulolytic enzymes and prokaryotic enzymes, is the caecum, and the mechanism by which bacterial enzymes reach the distant caecum lumen has remained so far mysterious. Here, we provide a characterisation of the path through which bacterial CAZymes produced in the gills of the shipworm Lyrodus pedicellatus reach the distant caecum to contribute to the digestion of wood. RESULTS: Through a combination of transcriptomics, proteomics, X-ray microtomography, electron microscopy studies and in vitro biochemical characterisation, we show that wood-digesting enzymes produced by symbiotic bacteria are localised not only in the gills, but also in the lumen of the food groove, a stream of mucus secreted by gill cells that carries food particles trapped by filter feeding to the mouth. Bacterial CAZymes are also present in the crystalline style and in the caecum of their shipworm host, suggesting a unique pathway by which enzymes involved in a symbiotic interaction are transported to their site of action. Finally, we characterise in vitro four new bacterial glycosyl hydrolases and a lytic polysaccharide monooxygenase identified in our transcriptomic and proteomic analyses as some of the major bacterial enzymes involved in this unusual biological system. CONCLUSION: Based on our data, we propose that bacteria and their enzymes are transported from the gills along the food groove to the shipworm's mouth and digestive tract, where they aid in wood digestion

Uncovering the molecular mechanisms of lignocellulose digestion in shipworms

Abstract Lignocellulose forms the structural framework of woody plant biomass and represents the most abundant carbon source in the biosphere. Turnover of woody biomass is a critical component of the global carbon cycle, and the enzymes involved are of increasing industrial importance as industry moves away from fossil fuels to renewable carbon resources. Shipworms are marine bivalve molluscs that digest wood and play a key role in global carbon cycling by processing plant biomass in the oceans. Previous studies suggest that wood digestion in shipworms is dominated by enzymes produced by endosymbiotic bacteria found in the animal’s gills, while little is known about the identity and function of endogenous enzymes produced by shipworms. Using a combination of meta-transcriptomic, proteomic, imaging and biochemical analyses, we reveal a complex digestive system dominated by uncharacterized enzymes that are secreted by a specialized digestive gland and that accumulate in the cecum, where wood digestion occurs. Using a combination of transcriptomics, proteomics, and microscopy, we show that the digestive proteome of the shipworm Lyrodus pedicellatus is mostly composed of enzymes produced by the animal itself, with a small but significant contribution from symbiotic bacteria. The digestive proteome is dominated by a novel 300 kDa multi-domain glycoside hydrolase that functions in the hydrolysis of β-1,4-glucans, the most abundant polymers in wood. These studies allow an unprecedented level of insight into an unusual and ecologically important process for wood recycling in the marine environment, and open up new biotechnological opportunities in the mobilization of sugars from lignocellulosic biomass

Lignocellulose degradation mechanisms across the Tree of Life.

Organisms use diverse mechanisms involving multiple complementary enzymes, particularly glycoside hydrolases (GHs), to deconstruct lignocellulose. Lytic polysaccharide monooxygenases (LPMOs) produced by bacteria and fungi facilitate deconstruction as does the Fenton chemistry of brown-rot fungi. Lignin depolymerisation is achieved by white-rot fungi and certain bacteria, using peroxidases and laccases. Meta-omics is now revealing the complexity of prokaryotic degradative activity in lignocellulose-rich environments. Protists from termite guts and some oomycetes produce multiple lignocellulolytic enzymes. Lignocellulose-consuming animals secrete some GHs, but most harbour a diverse enzyme-secreting gut microflora in a mutualism that is particularly complex in termites. Shipworms however, house GH-secreting and LPMO-secreting bacteria separate from the site of digestion and the isopod Limnoria relies on endogenous enzymes alone. The omics revolution is identifying many novel enzymes and paradigms for biomass deconstruction, but more emphasis on function is required, particularly for enzyme cocktails, in which LPMOs may play an important role.The work of the teams at York, Portsmouth and Cambridge on development of ideas expressed in this review was supported by grants from BBSRC (BB/H531543/1, BB/L001926/1, BB/1018492/1, BB/K020358/1). The workshop was supported by a US Partnering grant from BBSRC (BB/G016208/1) to Cragg and a BBSRC/FAPESP grant to Bruce (BB/1018492/1). Watts was supported by Marie Curie FP7-RG 276948. Goodell acknowledges support from USDA Hatch Project S-1041 VA-136288. Distel acknowledges support from NSF Award IOS1442759 and NIH Award Number U19 TW008163. Beckham thanks the US Department of Energy Bioenergy Technologies Office for funding. We appreciated the hospitality of the Linnean Society in allowing us to meet in inspirational surroundings under portraits of Linnaeus, Darwin and Wallace.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.cbpa.2015.10.01

The Distance to NGC 1316 (Fornax A) From Observations of Four Type Ia Supernovae

The giant elliptical galaxy NGC 1316 (Fornax A) is a well-studied member of the Fornax Cluster and a prolific producer of Type Ia supernovae, having hosted four observed events since 1980. Here we present detailed optical and near-infrared light curves of the spectroscopically normal SN 2006dd. These data are used, along with previously published photometry of the normal SN 1980N and SN 1981D, and the fast-declining, low-luminosity SN 2006mr, to compute independent estimates of the host reddening for each supernova, and the distance to NGC 1316. From the three normal supernovae, we find a distance of 17.8 +/- 0.3 (random) +/- 0.3 (systematic) Mpc for Ho = 72. Distance moduli derived from the "EBV" and Tripp methods give values that are mutually consistent to 4 -- 8%. Moreover, the weighted means of the distance moduli for these three SNe for three methods agree to within 3%. This consistency is encouraging and supports the premise that Type Ia supernovae are reliable distance indicators at the 5% precision level or better. On the other hand, the two methods used to estimate the distance of the fast-declining SN 2006mr both yield a distance to NGC 1316 which is 25-30% larger. This disparity casts doubt on the suitability of fast-declining events for estimating extragalactic distances. Modest-to-negligible host galaxy reddening values are derived for all four supernovae. Nevertheless, two of them (SN 2006dd and SN 2006mr) show strong NaID interstellar lines in the host galaxy system. The strength of this absorption is completely inconsistent with the small reddening values derived from the supernova light curves if the gas in NGC 1316 is typical of that found in the interstellar medium of the Milky Way. In addition, the equivalent width of the NaID lines in SN 2006dd appear to have weakened significantly some 100-150 days after explosion.Comment: 50 pages, 13 figures, 10 tables; constructive comments welcome. Accepted for publication in A