Luísa M. S. Borges

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

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.

Laboratory screening of tropical hardwoods for natural resistance to the marine borer Limnoria quadripunctata: The role of leachable and non-leachable factors

Abstract The marine borer Limnoria ingests essential wood components including the extractives the wood contains. Some extractives may confer borer resistance on certain timbers. Feeding by Limnoria correlates with the rate of production of faecal pellets. The faecal pellet production rate and mortality on over 40 test timbers and non-resistant Pinus sylvestris sapwood 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 affected Limnoria as strongly as timbers reputed for durability in marine construction. Wood of Minquartia guianensis, Nectandra rubra and Bruguiera gymnorhiza caused high mortality, and pellet production on them was less than 10% of production on P. sylvestris. Suppressed feeding rates, but with no heavy mortality, were observed on known durable species such as Chlorocardium rodiei, Dicorynia guianensis, Lophira alata and Nauclea trillesii, but also on Cynometra ananta, Distemonanthus benthamianus, Enterolobium schomburgkii, Goupia glabra, Hymenaea courabil, Mammea africana, Shorea sp. and Sacoglottis guianensis. Leachate from B. gymnorhiza, G. glabra, H. coubaril, N. rubra and Shorea sp. caused high mortality. These short-term bioassays thus detected clear differences between wood species in their resistance to Limnoria that matched findings from long-term marine trials, while indicating new species worthy of detailed testing.

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.

Lyrodus mersinensis sp. nov. (Bivalvia: Teredinidae) another cryptic species in the Lyrodus pedicellatus (Quatrefages, 1849) complex

New data from barcode index numbers (BINs) and 28S rRNA gene sequences confirm a cryptic species pair in Lyrodus pedicellatus from the eastern Mediterranean and European Atlantic coasts. Therefore, it is paramount to associate the new species to a scientific name for a reliable reference system of biological information. To this end, we describe Lyrodus mersinensis sp. nov., another cryptic species in the L. pedicellatus complex, and redescribe the `true´ L. pedicellatus. Both the description and redescription are based on molecular diagnostic characters obtained from sequences of the mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S rRNA genes. The 18S rRNA gene sequences did not yield diagnostic characters to distinguish these species. A morphological diagnosis of pedicellatus-like Lyrodus species is also provided.

PERFORMANCE OF COPPER AZOLE TREATED SOFTWOODS EXPOSED TO MARINE BORERS

Wooden material has been used for shipbuilding and structural purposes in the marine environment since ancient times. Wood being used in the sea water can be damaged by marine wood boring organisms, which can turn marine wooden structures unserviceable with great economic cost. Using naturally durable species and preservative treated wood can increase the service life of wooden maritime structures and avoid or minimise the damages caused by marine borers. In this study, Scots pine (Pinus sylvestris), Black pine (Pinus nigra) and Turkish fir (Abies bornmulleriana) naturally grown and economically important wood species in Turkey were treated with copper-azole and evaluated in marine trials for 7 and 14 months in the Western Black Sea region. In this experiment, Teredo navalis was the only teredinid species identified. Copper-azole treated fir and Scots pine specimens suffered no attack, after 7 and 14 months exposure, except four panels which suffered minor damage. However, copper-azole treated Black pine panels were moderately damaged, and all of the control panels of the softwoods were strongly attacked. The average largest shell diameter was found to be 4,79 mm in Scots pine, while the longest pallets (4,71 mm) was found in Black pine. All untreated test panels scored an average of 4 (heavily attacked) after a 14 month period. The cellulose ratio of Black pine decreased from 56 % to 50 %, and the holo-cellulose ratio from 76 % to 71 %. The treated samples showed resistance against marine borers although the copper (cu) leaching was high during the 14 months exposure underwater.