BackgroundBivalve 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.ResultsA 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.ConclusionsCombined 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.

Marine wood-boring teredinids, some of the most destructive wood borers in the sea, are a particularly difficult group to identify from morphological features. While in most bivalve species shell features are used as diagnostic characters, in the teredinids shell morphology shows high intraspecific variation and thus identification is based almost entirely on the morphology of the pallets. In the present study we aimed at improving ‘taxonomic resolution’ in teredinids by combining morphological evidence with mitochondrial and nuclear DNA sequences, respectively Cytochromec oxidase subunitI and small subunit rRNA 18S gene, to generate more rigorous and accessible identifications. DNA barcodes of Atlantic and Mediterranean populations of Lyrodus pedicellatus diverged by ~20%, suggesting cryptic species in the morphospecies L. pedicellatus. The low intraspecific divergence found in barcodes of specimens of Nototeredo norvagica (0.78%) confirms that Atlantic and Mediterranean forms of N. norvagica, the latter sometimes reported as Teredo utriculus, are the same species. Teredothyra dominicensis was found for the first time in the Mediterranean. A match was obtained between our 18S sequences and sequences of T. dominicensis from Netherlands Antilles, confirming that T. dominicensis in the Mediterranean is the same species that occurs in the Caribbean. There were differences in 18S sequences between Bankia carinata from the Mediterranean and Caribbean, which may indicate cryptic species.

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Annelid polychaetes have been seldom the focus of dedicated DNA barcoding studies, despite their ecological relevance and often dominance, particularly in soft-bottom estuarine and coastal marine ecosystems. Here, we report the first assessment of the performance of DNA barcodes in the discrimination of shallow water polychaete species from the southern European Atlantic coast, focusing on specimens collected in estuaries and coastal ecosystems of Portugal. We analysed cytochrome oxidase I DNA barcodes (COI-5P) from 164 specimens, which were assigned to 51 morphospecies. To our data set from Portugal, we added available published sequences selected from the same species, genus or family, to inspect for taxonomic congruence among studies and collection location. The final data set comprised 290 specimens and 79 morphospecies, which generated 99 Barcode Index Numbers (BINs) within Barcode of Life Data Systems (BOLD). Among these, 22 BINs were singletons, 47 other BINs were concordant, confirming the initial identification based on morphological characters, and 30 were discordant, most of which consisted on multiple BINs found for the same morphospecies. Some of the most prominent cases in the latter category include Hediste diversicolor (O.F. Müller, 1776) (7), Eulalia viridis (Linnaeus, 1767) (2) and Owenia fusiformis (delle Chiaje, 1844) (5), all of them reported from Portugal and frequently used in ecological studies as environmental quality indicators. Our results for these species showed discordance between molecular lineages and morphospecies, or added additional relatively divergent lineages. The potential inaccuracies in environmental assessments, where underpinning polychaete species diversity is poorly resolved or clarified, demand additional and extensive investigation of the DNA barcode diversity in this group, in parallel with alpha taxonomy efforts.

In this study we compared DNA barcode-suggested species boundaries with morphology-based species identifications in the amphipod fauna of the southern European Atlantic coast. DNA sequences of the cytochrome c oxidase subunit I barcode region (COI-5P) were generated for 43 morphospecies (178 specimens) collected along the Portuguese coast which, together with publicly available COI-5P sequences, produced a final dataset comprising 68 morphospecies and 295 sequences. Seventy-five BINs (Barcode Index Numbers) were assigned to these morphospecies, of which 48 were concordant (i.e., 1 BIN = 1 species), 8 were taxonomically discordant, and 19 were singletons. Twelve species had matching sequences (<2% distance) with conspecifics from distant locations (e.g., North Sea). Seven morphospecies were assigned to multiple, and highly divergent, BINs, including specimens of Corophium multisetosum (18% divergence) and Dexamine spiniventris (16% divergence), which originated from sampling locations on the west coast of Portugal (only about 36 and 250 km apart, respectively). We also found deep divergence (4%-22%) among specimens of seven species from Portugal compared to those from the North Sea and Italy. The detection of evolutionarily meaningful divergence among populations of several amphipod species from southern Europe reinforces the need for a comprehensive re-assessment of the diversity of this faunal group.

Available online Keywords: Biodegradation of wood Marine wood-borers Teredinids Shipworm Limnoriids Gribble borer hazard European coastal watersThe activity of marine wood-borers causes great destruction in maritime wooden structures. Therefore, the aim of this study was to evaluate the hazard posed by marine wood-borers in fifteen European sites, to assist authorities and researchers concerned with the protection of wood in the sea. In northern Europe, Teredo navalis is the species that poses the highest borer hazard while in the Atlantic coast of southern Europe Lyrodus pedicellatus is the most destructive species, with the exception of two sites in Portugal. In these sites, Limnoria tripunctata was more destructive than L. pedicellatus. In the Mediterranean both T. navalis and L. pedicellatus pose a very high borer hazard to wooden structures.Salinity and temperature emerged as the environmental conditions that best explain the occurrence and abundance of wood boring species in the sites surveyed. Three of the species highlighted in this study are warm water species. Therefore their activity might increase in the future, due to global warming. Considering that wood is still a very valuable material for construction, its use for maritime construction should be favoured. Thus research to improve the durability of wooden materials in the marine environment is of paramount importance.

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.

The marine borerLimnoriaingests essential wood components including the extractives the wood contains. Some extractives may confer borer resistance on certain timbers. Feeding byLimnoriacorrelates with the rate of production of faecal pellets. The faecal pellet production rate and mortality on over 40 test timbers and non-resistantPinus sylvestrissapwood was measured over 15 days. By placing animals in leachate from wood and with wood in flowing seawater, the effects of leaching-resistant and water-soluble compounds were measured. Some previously untested timbers affectedLimnoriaas strongly as timbers reputed for durability in marine construction. Wood ofMinquartia guianensis,Nectandra rubraandBruguiera gymnorhizacaused high mortality, and pellet production on them was less than 10% of production onP. sylvestris. Suppressed feeding rates, but with no heavy mortality, were observed on known durable species such asChlorocardium rodiei,Dicorynia guianensis, Lophira alataandNauclea trillesii, but also onCynometra ananta,Distemonanthus benthamianus,Enterolobium schomburgkii,Goupia glabra,Hymenaea courabil,Mammea africana,Shoreasp. andSacoglottis guianensis. Leachate fromB. gymnorhiza,G. glabra,H. coubaril,N. rubraandShoreasp. caused high mortality. These short-term bioassays thus detected clear differences between wood species in their resistance toLimnoriathat matched findings from long-term marine trials, while indicating new species worthy of detailed testing.