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Map of the sampling sites for shipworm abundance, and sea surface salinity and temperature along the Swedish coast and around the Danish island of Bornholm. Filled circles represents sites visited during the 1970s by Norman (1977). Site: (1) Tj ̈rn ̈, (2) Kristineberg, (3) Tr ̈sl ̈vsl ̈ge, (4) Gr ̈tvik, (5) Arild, (6) M ̈lle/H ̈gan ̈s, (7) A ̊ labodarna, (8) Barseb ̈ckshamn/ Lund ̊kra, (9) Klagshamn, (10) Falsterbo/H ̈llviken, (11) Sk ̊re, (12) Gisl ̈vsl ̈ge, (13) Ystad, (14) Rønne, (15) Sandvig, (16) Gudhjem, (17) Svaneke, (18) Nexø. Dotted lines represent the boundary of different salinity regimes.
Source publication
Shipworms (teredinids) are highly specialized marine bivalves that consume terrestrially derived wood. Changes in environmental variables may result in shipworms spreading into the Baltic Sea - which would have devastating consequences for maritime cultural heritage and submerged wooden structures. We investigated the distribution and abundance of...
Contexts in source publication
Context 1
... (family Teredinidae) are highly specialized marine bivalves that efficiently and rapidly decompose and consume terrestrially derived wood in the ocean with the aid of intracel- lular cellulolytic and nitrogen-fixing symbionts (Distel et al. , 2002). Shipworms play a major ecological role in mangrove systems and are an important link in the turnover of carbon from terrestrial ecosystems in temperate seas (Turner, 1966). This brings them into conflict with human interests because they can cause extensive damage to submerged man-made wooden structures. In the USA alone, the economic consequences of shipworm damage to ships, fishing equipment and wooden structures in marine environments have been estimated to be US$ 200 million per year (Cohen & Carlton, 1995). Studies on shipworms date back to the 18th century (Clapp & Kenk, 1963), but information on the distribution of many species is still scattered (Borges et al. , 2014). The geographic range of a species is determined by complex interactions among environmental and biological factors and is also affected by evolutionary processes such as adaptation (Cox & Moore, 2009). For centuries, a primary goal for biogeographers has been to identify factors that determine the distribution of species (e.g. Wallace, 1876; MacArthur & Wilson, 1963). Among these, salinity and temperature are overridingly important abiotic determinants of species distributions, especially in estuarine and coastal ecosystems (Kinne, 1963; Bonsdorff, 2006; Ojaveer et al. , 2010). Previous studies have also implicated these factors in control- ling the distribution of shipworms (Scheltema & Truitt, 1954; Hoestland & Brasselet, 1968; Culliney, 1970; Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972; Saraswathy & Nair, 1974; Hoagland, 1986). Of about 65 described shipworm species (Turner, 1966), the widely distributed, euryhaline species Teredo navalis L. is the most investigated and the most abundant teredinid in Sweden (Norman, 1976, 1977). Teredo navalis broods its offspring until the larvae have reached straight-hinge stage, at which time the free-swimming larvae are released to the plankton, where they grow for a further 2 –5 weeks (Grave, 1928; Imai et al. , 1950; Loosanoff & Davis, 1963; Culliney, 1975). The species shows a wide tolerance to both temperature and salinity (reviewed in Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972). Release of larvae can occur in salinities , 9 PSU and temperatures , 11 C 8 (Roch, 1940), although larvae are unable to survive at salinities less than 6– 7.5 PSU (M’Gonigle, 1926; Hoagland, 1986). The second member of Teredinidae recorded in Swedish waters is the oviparous species Psiloteredo megotara (Hanley). Little is known about this species’ biology and ecology. However, it shows higher growth rate, is less tolerant to low salinities, and is better adapted to low temperature than T. navalis (Dons, 1940; Norman, 1977). There is increasing concern that climate change will lead to shifts in the geographic ranges of ecologically and economic- ally important species. Several studies report range shifts due to climate change in terrestrial and marine species (e.g. Perry et al. , 2005: Harley et al. , 2006; Parmesan, 2006; Wernberg et al. , 2011), and changing distribution patterns of shipworms have also been reported recently (Sordyl et al. , 1998; Tuente et al. , 2002; Borges et al. , 2010, 2014). At the beginning of the 21st century rumours circulated about possible range-expansion of shipworms in Scandinavian waters: Swedish harbour authorities noticed an increased level of shipworm attacks on wooden constructions (Port of Gothenburg personal communication, Schlyter, 2009), and during the summer of 2002 shipworms were observed for the first time on the Danish island of Bornholm (Olsen, 2003). Shortly thereafter, marine archaeologists began to raise concerns over the risk of shipworms spreading into the Baltic Sea, a brackish water area with many valuable and well- preserved wooden wrecks (Olsson, 2006). Hypotheses of range expansion are perhaps most easily tested by comparing new range records with historical distribution data. We used a 35-year-old investigation of the geographical distribution of shipworms in Swedish waters as a baseline (Norman, 1977). Norman (1977) found high fre- quencies of T. navalis along the Swedish west coast from close to the Norwegian border (Koster Islands) southwards to the entrance to the Sound at M ̈lle (Figure 1). Beyond this point abundances declined and the most southern point of shipworm recruitment was observed at Klagshamn. The second species, P. megotara , was rare with very few specimens at some sites from the Koster islands down to M ̈lle. We repeated Norman’s (1977) study to assess whether shipworms have changed their range over the past 35 years. Furthermore, in order to explore whether any shifts in the range of shipworms could be correlated with temporal changes in environmental variables, we compared historical and present-day sea surface temperature and sea surface salinity data. We investigated occurrence of teredinids from the Skagerrak to the Baltic Sea (Figure 1). This region is a transitional area with complex hydrography and strong salinity gradients between the North Sea and Baltic Sea (Gustafsson & Stigebrandt, 1996). The oceanographic system is barotropi- cally driven mainly by differences in sea levels and wind patterns (Stigebrandt & Gustafsson, 2002). Large inflow of high saline water into the Baltic Sea through the Danish Straits and the Sound is limited by the topography and occurs only occasionally (Schinke & Matthaus, 1998). The dominant sea surface current is west along the Swedish south coast, and northbound along the Swedish west coast. However, daily variation occurs at local scales. Coastal sea surface temperature shows wide seasonal variation ( 2 4– 27 C 8 ) (http:// www.smhi.se). Sea surface salinity in the study area ranged from fully marine conditions in the Skagerrak ( . 30 PSU) down to brackish levels ( 7 PSU) along the southern coast of Sweden and around Bornholm (). The study was conducted along the Swedish west and south coasts and around the Danish island of Bornholm during 2006 – 2008. In 2006, the distribution of shipworms was investigated at 9 sites that partly followed the sites investigated in Norman (1977) (Figure 1). In order to increase spatial reso- lution of the investigation, and to study a possible range expansion of shipworm infestations in the Baltic Sea, five additional harbours along the Swedish coast, and four additional harbours around Bornholm, Denmark, were also included in 2007 and 2008 survey (Figure 1). At each site, four unplaned pine ( Pinus sylvestris ) panels (25 × 75 × 200 mm) were submerged at a depth of 0.5–2 m below sea surface in the spring of each year. Holes (ø 25 mm) were drilled in the centre of the panels, the panels attached to a polypropylene rope with cable ties, and then suspended vertically in the water. Panels were collected one year later, surface fouling organisms were removed, and the panels were stored in the freezer ( 2 20 8 C). In order to esti- mate the shipworm abundance, panels were analysed by X-ray radiography (Siemens – Elema Mobilett II 40 kV and 14 mA). Before X-ray, panels were thawed and dried at room temperature for 48 h. The number of shells visible was counted over the whole X-ray photo area, and abundance (per dm 2 ) calculated for the exposed surface of the panel (4.275 dm 2 per panel). Yearly mean values of T. navalis abundance (individuals dm 2 2 ) at each site were calculated and analysed in a 2-way analysis of variance (ANOVA) with Decade as a 2-level, and Site as a 9-level, fixed factor. Data from 2006 –2008 were analysed in two separate statistical tests due to lost wooden panels at some sites in 2006 and extension of sites in 2007 and 2008. The abundance data from 2006 were statistically analysed in a one-way ANOVA with Site as a fixed 9-level factor. The abundance data from 2007 and 2008 were statistically analysed in a two-way ANOVA with Year as a 2-level random factor and Site as a 17-level fixed factor. Means were compared using the Student-Newman-Keuls (SNK) procedure (Underwood, 1997). All data were tested for homogeneity of variances with Cochran’s test (Underwood, 1997). The abundance of P. megotara was very low during both study periods with only a few observations of single individuals, and therefore no statistical analysis of these data was performed. Sea surface temperature and salinity data along the Swedish west and south coast were analysed for the summer period (May to October – the season for adult T. navalis reproduction and larval metamorphosis). Data were obtained from the Swedish Meteorological and Hydrological Institute (). Additional salinity and temperature data were also obtained from the marine biological stations at Kristineberg and Tj ̈rn ̈ (, Figure 1). In order to investigate a possible long-term change in sea surface temperature from the 1970s to the 2000s, 3 daily averages of temperature data were extracted from Kristineberg (handwritten logbook and ) each month during the study season (May –October) from 1971 – 1973 and 2006–2008. Long-term high-resolution temperature data were only available for Kristineberg and therefore possible changes in sea surface temperature at this site were assumed to be representative for the whole study area. Data were ...
Context 2
... aid of intracel- lular cellulolytic and nitrogen-fixing symbionts (Distel et al. , 2002). Shipworms play a major ecological role in mangrove systems and are an important link in the turnover of carbon from terrestrial ecosystems in temperate seas (Turner, 1966). This brings them into conflict with human interests because they can cause extensive damage to submerged man-made wooden structures. In the USA alone, the economic consequences of shipworm damage to ships, fishing equipment and wooden structures in marine environments have been estimated to be US$ 200 million per year (Cohen & Carlton, 1995). Studies on shipworms date back to the 18th century (Clapp & Kenk, 1963), but information on the distribution of many species is still scattered (Borges et al. , 2014). The geographic range of a species is determined by complex interactions among environmental and biological factors and is also affected by evolutionary processes such as adaptation (Cox & Moore, 2009). For centuries, a primary goal for biogeographers has been to identify factors that determine the distribution of species (e.g. Wallace, 1876; MacArthur & Wilson, 1963). Among these, salinity and temperature are overridingly important abiotic determinants of species distributions, especially in estuarine and coastal ecosystems (Kinne, 1963; Bonsdorff, 2006; Ojaveer et al. , 2010). Previous studies have also implicated these factors in control- ling the distribution of shipworms (Scheltema & Truitt, 1954; Hoestland & Brasselet, 1968; Culliney, 1970; Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972; Saraswathy & Nair, 1974; Hoagland, 1986). Of about 65 described shipworm species (Turner, 1966), the widely distributed, euryhaline species Teredo navalis L. is the most investigated and the most abundant teredinid in Sweden (Norman, 1976, 1977). Teredo navalis broods its offspring until the larvae have reached straight-hinge stage, at which time the free-swimming larvae are released to the plankton, where they grow for a further 2 –5 weeks (Grave, 1928; Imai et al. , 1950; Loosanoff & Davis, 1963; Culliney, 1975). The species shows a wide tolerance to both temperature and salinity (reviewed in Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972). Release of larvae can occur in salinities , 9 PSU and temperatures , 11 C 8 (Roch, 1940), although larvae are unable to survive at salinities less than 6– 7.5 PSU (M’Gonigle, 1926; Hoagland, 1986). The second member of Teredinidae recorded in Swedish waters is the oviparous species Psiloteredo megotara (Hanley). Little is known about this species’ biology and ecology. However, it shows higher growth rate, is less tolerant to low salinities, and is better adapted to low temperature than T. navalis (Dons, 1940; Norman, 1977). There is increasing concern that climate change will lead to shifts in the geographic ranges of ecologically and economic- ally important species. Several studies report range shifts due to climate change in terrestrial and marine species (e.g. Perry et al. , 2005: Harley et al. , 2006; Parmesan, 2006; Wernberg et al. , 2011), and changing distribution patterns of shipworms have also been reported recently (Sordyl et al. , 1998; Tuente et al. , 2002; Borges et al. , 2010, 2014). At the beginning of the 21st century rumours circulated about possible range-expansion of shipworms in Scandinavian waters: Swedish harbour authorities noticed an increased level of shipworm attacks on wooden constructions (Port of Gothenburg personal communication, Schlyter, 2009), and during the summer of 2002 shipworms were observed for the first time on the Danish island of Bornholm (Olsen, 2003). Shortly thereafter, marine archaeologists began to raise concerns over the risk of shipworms spreading into the Baltic Sea, a brackish water area with many valuable and well- preserved wooden wrecks (Olsson, 2006). Hypotheses of range expansion are perhaps most easily tested by comparing new range records with historical distribution data. We used a 35-year-old investigation of the geographical distribution of shipworms in Swedish waters as a baseline (Norman, 1977). Norman (1977) found high fre- quencies of T. navalis along the Swedish west coast from close to the Norwegian border (Koster Islands) southwards to the entrance to the Sound at M ̈lle (Figure 1). Beyond this point abundances declined and the most southern point of shipworm recruitment was observed at Klagshamn. The second species, P. megotara , was rare with very few specimens at some sites from the Koster islands down to M ̈lle. We repeated Norman’s (1977) study to assess whether shipworms have changed their range over the past 35 years. Furthermore, in order to explore whether any shifts in the range of shipworms could be correlated with temporal changes in environmental variables, we compared historical and present-day sea surface temperature and sea surface salinity data. We investigated occurrence of teredinids from the Skagerrak to the Baltic Sea (Figure 1). This region is a transitional area with complex hydrography and strong salinity gradients between the North Sea and Baltic Sea (Gustafsson & Stigebrandt, 1996). The oceanographic system is barotropi- cally driven mainly by differences in sea levels and wind patterns (Stigebrandt & Gustafsson, 2002). Large inflow of high saline water into the Baltic Sea through the Danish Straits and the Sound is limited by the topography and occurs only occasionally (Schinke & Matthaus, 1998). The dominant sea surface current is west along the Swedish south coast, and northbound along the Swedish west coast. However, daily variation occurs at local scales. Coastal sea surface temperature shows wide seasonal variation ( 2 4– 27 C 8 ) (http:// www.smhi.se). Sea surface salinity in the study area ranged from fully marine conditions in the Skagerrak ( . 30 PSU) down to brackish levels ( 7 PSU) along the southern coast of Sweden and around Bornholm (). The study was conducted along the Swedish west and south coasts and around the Danish island of Bornholm during 2006 – 2008. In 2006, the distribution of shipworms was investigated at 9 sites that partly followed the sites investigated in Norman (1977) (Figure 1). In order to increase spatial reso- lution of the investigation, and to study a possible range expansion of shipworm infestations in the Baltic Sea, five additional harbours along the Swedish coast, and four additional harbours around Bornholm, Denmark, were also included in 2007 and 2008 survey (Figure 1). At each site, four unplaned pine ( Pinus sylvestris ) panels (25 × 75 × 200 mm) were submerged at a depth of 0.5–2 m below sea surface in the spring of each year. Holes (ø 25 mm) were drilled in the centre of the panels, the panels attached to a polypropylene rope with cable ties, and then suspended vertically in the water. Panels were collected one year later, surface fouling organisms were removed, and the panels were stored in the freezer ( 2 20 8 C). In order to esti- mate the shipworm abundance, panels were analysed by X-ray radiography (Siemens – Elema Mobilett II 40 kV and 14 mA). Before X-ray, panels were thawed and dried at room temperature for 48 h. The number of shells visible was counted over the whole X-ray photo area, and abundance (per dm 2 ) calculated for the exposed surface of the panel (4.275 dm 2 per panel). Yearly mean values of T. navalis abundance (individuals dm 2 2 ) at each site were calculated and analysed in a 2-way analysis of variance (ANOVA) with Decade as a 2-level, and Site as a 9-level, fixed factor. Data from 2006 –2008 were analysed in two separate statistical tests due to lost wooden panels at some sites in 2006 and extension of sites in 2007 and 2008. The abundance data from 2006 were statistically analysed in a one-way ANOVA with Site as a fixed 9-level factor. The abundance data from 2007 and 2008 were statistically analysed in a two-way ANOVA with Year as a 2-level random factor and Site as a 17-level fixed factor. Means were compared using the Student-Newman-Keuls (SNK) procedure (Underwood, 1997). All data were tested for homogeneity of variances with Cochran’s test (Underwood, 1997). The abundance of P. megotara was very low during both study periods with only a few observations of single individuals, and therefore no statistical analysis of these data was performed. Sea surface temperature and salinity data along the Swedish west and south coast were analysed for the summer period (May to October – the season for adult T. navalis reproduction and larval metamorphosis). Data were obtained from the Swedish Meteorological and Hydrological Institute (). Additional salinity and temperature data were also obtained from the marine biological stations at Kristineberg and Tj ̈rn ̈ (, Figure 1). In order to investigate a possible long-term change in sea surface temperature from the 1970s to the 2000s, 3 daily averages of temperature data were extracted from Kristineberg (handwritten logbook and ) each month during the study season (May –October) from 1971 – 1973 and 2006–2008. Long-term high-resolution temperature data were only available for Kristineberg and therefore possible changes in sea surface temperature at this site were assumed to be representative for the whole study area. Data were analysed statistically using a mixed model ANOVA with Decade as a 2-level fixed factor, Year as a 3-level random factor nested within Decade, and Month as a 6-level fixed factor. In order to investigate possible short-term changes in sea surface temperature and salinity along the Swedish west coast during the study period (2006 – 2008), data were extracted from monitoring stations (H ̈gan ̈s, Lund ̊kra and H ̈llviken) close to sampling sites in the Sound (M ̈lle, Barseb ̈ckshamn and Faslterbo) (), as well as from Kristineberg () and Tj ̈rn ̈ ( Data were analysed using 2-way ANOVAs with Year as a 3-level random factor and Site as a 5-level fixed factor. In order to ...
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... 1970; Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972; Saraswathy & Nair, 1974; Hoagland, 1986). Of about 65 described shipworm species (Turner, 1966), the widely distributed, euryhaline species Teredo navalis L. is the most investigated and the most abundant teredinid in Sweden (Norman, 1976, 1977). Teredo navalis broods its offspring until the larvae have reached straight-hinge stage, at which time the free-swimming larvae are released to the plankton, where they grow for a further 2 –5 weeks (Grave, 1928; Imai et al. , 1950; Loosanoff & Davis, 1963; Culliney, 1975). The species shows a wide tolerance to both temperature and salinity (reviewed in Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972). Release of larvae can occur in salinities , 9 PSU and temperatures , 11 C 8 (Roch, 1940), although larvae are unable to survive at salinities less than 6– 7.5 PSU (M’Gonigle, 1926; Hoagland, 1986). The second member of Teredinidae recorded in Swedish waters is the oviparous species Psiloteredo megotara (Hanley). Little is known about this species’ biology and ecology. However, it shows higher growth rate, is less tolerant to low salinities, and is better adapted to low temperature than T. navalis (Dons, 1940; Norman, 1977). There is increasing concern that climate change will lead to shifts in the geographic ranges of ecologically and economic- ally important species. Several studies report range shifts due to climate change in terrestrial and marine species (e.g. Perry et al. , 2005: Harley et al. , 2006; Parmesan, 2006; Wernberg et al. , 2011), and changing distribution patterns of shipworms have also been reported recently (Sordyl et al. , 1998; Tuente et al. , 2002; Borges et al. , 2010, 2014). At the beginning of the 21st century rumours circulated about possible range-expansion of shipworms in Scandinavian waters: Swedish harbour authorities noticed an increased level of shipworm attacks on wooden constructions (Port of Gothenburg personal communication, Schlyter, 2009), and during the summer of 2002 shipworms were observed for the first time on the Danish island of Bornholm (Olsen, 2003). Shortly thereafter, marine archaeologists began to raise concerns over the risk of shipworms spreading into the Baltic Sea, a brackish water area with many valuable and well- preserved wooden wrecks (Olsson, 2006). Hypotheses of range expansion are perhaps most easily tested by comparing new range records with historical distribution data. We used a 35-year-old investigation of the geographical distribution of shipworms in Swedish waters as a baseline (Norman, 1977). Norman (1977) found high fre- quencies of T. navalis along the Swedish west coast from close to the Norwegian border (Koster Islands) southwards to the entrance to the Sound at M ̈lle (Figure 1). Beyond this point abundances declined and the most southern point of shipworm recruitment was observed at Klagshamn. The second species, P. megotara , was rare with very few specimens at some sites from the Koster islands down to M ̈lle. We repeated Norman’s (1977) study to assess whether shipworms have changed their range over the past 35 years. Furthermore, in order to explore whether any shifts in the range of shipworms could be correlated with temporal changes in environmental variables, we compared historical and present-day sea surface temperature and sea surface salinity data. We investigated occurrence of teredinids from the Skagerrak to the Baltic Sea (Figure 1). This region is a transitional area with complex hydrography and strong salinity gradients between the North Sea and Baltic Sea (Gustafsson & Stigebrandt, 1996). The oceanographic system is barotropi- cally driven mainly by differences in sea levels and wind patterns (Stigebrandt & Gustafsson, 2002). Large inflow of high saline water into the Baltic Sea through the Danish Straits and the Sound is limited by the topography and occurs only occasionally (Schinke & Matthaus, 1998). The dominant sea surface current is west along the Swedish south coast, and northbound along the Swedish west coast. However, daily variation occurs at local scales. Coastal sea surface temperature shows wide seasonal variation ( 2 4– 27 C 8 ) (http:// www.smhi.se). Sea surface salinity in the study area ranged from fully marine conditions in the Skagerrak ( . 30 PSU) down to brackish levels ( 7 PSU) along the southern coast of Sweden and around Bornholm (). The study was conducted along the Swedish west and south coasts and around the Danish island of Bornholm during 2006 – 2008. In 2006, the distribution of shipworms was investigated at 9 sites that partly followed the sites investigated in Norman (1977) (Figure 1). In order to increase spatial reso- lution of the investigation, and to study a possible range expansion of shipworm infestations in the Baltic Sea, five additional harbours along the Swedish coast, and four additional harbours around Bornholm, Denmark, were also included in 2007 and 2008 survey (Figure 1). At each site, four unplaned pine ( Pinus sylvestris ) panels (25 × 75 × 200 mm) were submerged at a depth of 0.5–2 m below sea surface in the spring of each year. Holes (ø 25 mm) were drilled in the centre of the panels, the panels attached to a polypropylene rope with cable ties, and then suspended vertically in the water. Panels were collected one year later, surface fouling organisms were removed, and the panels were stored in the freezer ( 2 20 8 C). In order to esti- mate the shipworm abundance, panels were analysed by X-ray radiography (Siemens – Elema Mobilett II 40 kV and 14 mA). Before X-ray, panels were thawed and dried at room temperature for 48 h. The number of shells visible was counted over the whole X-ray photo area, and abundance (per dm 2 ) calculated for the exposed surface of the panel (4.275 dm 2 per panel). Yearly mean values of T. navalis abundance (individuals dm 2 2 ) at each site were calculated and analysed in a 2-way analysis of variance (ANOVA) with Decade as a 2-level, and Site as a 9-level, fixed factor. Data from 2006 –2008 were analysed in two separate statistical tests due to lost wooden panels at some sites in 2006 and extension of sites in 2007 and 2008. The abundance data from 2006 were statistically analysed in a one-way ANOVA with Site as a fixed 9-level factor. The abundance data from 2007 and 2008 were statistically analysed in a two-way ANOVA with Year as a 2-level random factor and Site as a 17-level fixed factor. Means were compared using the Student-Newman-Keuls (SNK) procedure (Underwood, 1997). All data were tested for homogeneity of variances with Cochran’s test (Underwood, 1997). The abundance of P. megotara was very low during both study periods with only a few observations of single individuals, and therefore no statistical analysis of these data was performed. Sea surface temperature and salinity data along the Swedish west and south coast were analysed for the summer period (May to October – the season for adult T. navalis reproduction and larval metamorphosis). Data were obtained from the Swedish Meteorological and Hydrological Institute (). Additional salinity and temperature data were also obtained from the marine biological stations at Kristineberg and Tj ̈rn ̈ (, Figure 1). In order to investigate a possible long-term change in sea surface temperature from the 1970s to the 2000s, 3 daily averages of temperature data were extracted from Kristineberg (handwritten logbook and ) each month during the study season (May –October) from 1971 – 1973 and 2006–2008. Long-term high-resolution temperature data were only available for Kristineberg and therefore possible changes in sea surface temperature at this site were assumed to be representative for the whole study area. Data were analysed statistically using a mixed model ANOVA with Decade as a 2-level fixed factor, Year as a 3-level random factor nested within Decade, and Month as a 6-level fixed factor. In order to investigate possible short-term changes in sea surface temperature and salinity along the Swedish west coast during the study period (2006 – 2008), data were extracted from monitoring stations (H ̈gan ̈s, Lund ̊kra and H ̈llviken) close to sampling sites in the Sound (M ̈lle, Barseb ̈ckshamn and Faslterbo) (), as well as from Kristineberg () and Tj ̈rn ̈ ( Data were analysed using 2-way ANOVAs with Year as a 3-level random factor and Site as a 5-level fixed factor. In order to investigate if the abundance of T. navalis was correlated to the environmental variables, yearly mean values for 2006 – 2008 at different sites (Tj ̈rn ̈, Kristineberg, M ̈lle/H ̈gan ̈s, Barseb ̈ckshamn/Lund ̊kra and Falsterbo/H ̈llviken) were calculated, log-transformed and compared with sea surface temperature and salinity data using simple linear regression. No evidence for range expansion of T. navalis along the Swedish coast between the 1970s and the 2000s was detected (Figures 2 & 3), although we found one individual at Falsterbo, a site that was not investigated in the 1970s (Figure 3B). However, we found a statistically significant interaction between the effects of Decade and Site on shipworm abundance (Table 1). The mean abundance of T. navalis at one site (Arild) was significantly (SNK, P , 0.05) higher in samples from the 2000s (Figure 2). There were no statistically significant differences in shipworm abundances at the other sites (SNK, P . 0.05), although at Barseb ̈ckshamn, T. navalis was only observed in the 2000s (Figure 2). The presence of P. megotara was similar during the two periods with observations of single individuals at Tj ̈rn ̈, Kristineberg, Tr ̈sl ̈vsl ̈ge and M ̈lle (Table 2). Analysis of T. navalis abundance in 2007 and 2008 showed no statistically significant interaction between the main factors Year and Site (Table 3, Figure 3B), however there were statistically significant effects of both of these factors independently (Table 3). Mean T. navalis ...
Context 4
... water area with many valuable and well- preserved wooden wrecks (Olsson, 2006). Hypotheses of range expansion are perhaps most easily tested by comparing new range records with historical distribution data. We used a 35-year-old investigation of the geographical distribution of shipworms in Swedish waters as a baseline (Norman, 1977). Norman (1977) found high fre- quencies of T. navalis along the Swedish west coast from close to the Norwegian border (Koster Islands) southwards to the entrance to the Sound at M ̈lle (Figure 1). Beyond this point abundances declined and the most southern point of shipworm recruitment was observed at Klagshamn. The second species, P. megotara , was rare with very few specimens at some sites from the Koster islands down to M ̈lle. We repeated Norman’s (1977) study to assess whether shipworms have changed their range over the past 35 years. Furthermore, in order to explore whether any shifts in the range of shipworms could be correlated with temporal changes in environmental variables, we compared historical and present-day sea surface temperature and sea surface salinity data. We investigated occurrence of teredinids from the Skagerrak to the Baltic Sea (Figure 1). This region is a transitional area with complex hydrography and strong salinity gradients between the North Sea and Baltic Sea (Gustafsson & Stigebrandt, 1996). The oceanographic system is barotropi- cally driven mainly by differences in sea levels and wind patterns (Stigebrandt & Gustafsson, 2002). Large inflow of high saline water into the Baltic Sea through the Danish Straits and the Sound is limited by the topography and occurs only occasionally (Schinke & Matthaus, 1998). The dominant sea surface current is west along the Swedish south coast, and northbound along the Swedish west coast. However, daily variation occurs at local scales. Coastal sea surface temperature shows wide seasonal variation ( 2 4– 27 C 8 ) (http:// www.smhi.se). Sea surface salinity in the study area ranged from fully marine conditions in the Skagerrak ( . 30 PSU) down to brackish levels ( 7 PSU) along the southern coast of Sweden and around Bornholm (). The study was conducted along the Swedish west and south coasts and around the Danish island of Bornholm during 2006 – 2008. In 2006, the distribution of shipworms was investigated at 9 sites that partly followed the sites investigated in Norman (1977) (Figure 1). In order to increase spatial reso- lution of the investigation, and to study a possible range expansion of shipworm infestations in the Baltic Sea, five additional harbours along the Swedish coast, and four additional harbours around Bornholm, Denmark, were also included in 2007 and 2008 survey (Figure 1). At each site, four unplaned pine ( Pinus sylvestris ) panels (25 × 75 × 200 mm) were submerged at a depth of 0.5–2 m below sea surface in the spring of each year. Holes (ø 25 mm) were drilled in the centre of the panels, the panels attached to a polypropylene rope with cable ties, and then suspended vertically in the water. Panels were collected one year later, surface fouling organisms were removed, and the panels were stored in the freezer ( 2 20 8 C). In order to esti- mate the shipworm abundance, panels were analysed by X-ray radiography (Siemens – Elema Mobilett II 40 kV and 14 mA). Before X-ray, panels were thawed and dried at room temperature for 48 h. The number of shells visible was counted over the whole X-ray photo area, and abundance (per dm 2 ) calculated for the exposed surface of the panel (4.275 dm 2 per panel). Yearly mean values of T. navalis abundance (individuals dm 2 2 ) at each site were calculated and analysed in a 2-way analysis of variance (ANOVA) with Decade as a 2-level, and Site as a 9-level, fixed factor. Data from 2006 –2008 were analysed in two separate statistical tests due to lost wooden panels at some sites in 2006 and extension of sites in 2007 and 2008. The abundance data from 2006 were statistically analysed in a one-way ANOVA with Site as a fixed 9-level factor. The abundance data from 2007 and 2008 were statistically analysed in a two-way ANOVA with Year as a 2-level random factor and Site as a 17-level fixed factor. Means were compared using the Student-Newman-Keuls (SNK) procedure (Underwood, 1997). All data were tested for homogeneity of variances with Cochran’s test (Underwood, 1997). The abundance of P. megotara was very low during both study periods with only a few observations of single individuals, and therefore no statistical analysis of these data was performed. Sea surface temperature and salinity data along the Swedish west and south coast were analysed for the summer period (May to October – the season for adult T. navalis reproduction and larval metamorphosis). Data were obtained from the Swedish Meteorological and Hydrological Institute (). Additional salinity and temperature data were also obtained from the marine biological stations at Kristineberg and Tj ̈rn ̈ (, Figure 1). In order to investigate a possible long-term change in sea surface temperature from the 1970s to the 2000s, 3 daily averages of temperature data were extracted from Kristineberg (handwritten logbook and ) each month during the study season (May –October) from 1971 – 1973 and 2006–2008. Long-term high-resolution temperature data were only available for Kristineberg and therefore possible changes in sea surface temperature at this site were assumed to be representative for the whole study area. Data were analysed statistically using a mixed model ANOVA with Decade as a 2-level fixed factor, Year as a 3-level random factor nested within Decade, and Month as a 6-level fixed factor. In order to investigate possible short-term changes in sea surface temperature and salinity along the Swedish west coast during the study period (2006 – 2008), data were extracted from monitoring stations (H ̈gan ̈s, Lund ̊kra and H ̈llviken) close to sampling sites in the Sound (M ̈lle, Barseb ̈ckshamn and Faslterbo) (), as well as from Kristineberg () and Tj ̈rn ̈ ( Data were analysed using 2-way ANOVAs with Year as a 3-level random factor and Site as a 5-level fixed factor. In order to investigate if the abundance of T. navalis was correlated to the environmental variables, yearly mean values for 2006 – 2008 at different sites (Tj ̈rn ̈, Kristineberg, M ̈lle/H ̈gan ̈s, Barseb ̈ckshamn/Lund ̊kra and Falsterbo/H ̈llviken) were calculated, log-transformed and compared with sea surface temperature and salinity data using simple linear regression. No evidence for range expansion of T. navalis along the Swedish coast between the 1970s and the 2000s was detected (Figures 2 & 3), although we found one individual at Falsterbo, a site that was not investigated in the 1970s (Figure 3B). However, we found a statistically significant interaction between the effects of Decade and Site on shipworm abundance (Table 1). The mean abundance of T. navalis at one site (Arild) was significantly (SNK, P , 0.05) higher in samples from the 2000s (Figure 2). There were no statistically significant differences in shipworm abundances at the other sites (SNK, P . 0.05), although at Barseb ̈ckshamn, T. navalis was only observed in the 2000s (Figure 2). The presence of P. megotara was similar during the two periods with observations of single individuals at Tj ̈rn ̈, Kristineberg, Tr ̈sl ̈vsl ̈ge and M ̈lle (Table 2). Analysis of T. navalis abundance in 2007 and 2008 showed no statistically significant interaction between the main factors Year and Site (Table 3, Figure 3B), however there were statistically significant effects of both of these factors independently (Table 3). Mean T. navalis abundance in 2007 and 2008 was 32.36 + 7.33 and 20.94 + 6.12 individuals per dm 2 (mean + SEM) respectively. Mean abundance of T. navalis was also greatest at Kristineberg and Arild in all years 2006 – 2008 (Table 3, Figure 3B). Furthermore, when means from 2007 and 2008 were compared, we found statistically ( P , 0.05) greater abundances of T. navalis at Tr ̈sl ̈vsl ̈ge and Gr ̈tvik compared with the more southern sites (Figure 3B). No shipworms were found on the Swedish south coast (Sk ̊re, Gisl ̈vsl ̈ge and Ystad), or around the Danish island of Bornholm during the years 2006–2008 (Figure 3A, B). Sea surface temperature during the summer months at Kristineberg differed significantly between decades (Table 4). Mean temperature was 12.5% higher in the 2000s (16.01 + 0.44 8 C, mean + SEM) compared with the 1970s (14.23 + 0.47 8 C, mean + SEM). As expected, there was also a statistically significant difference in temperature between different months, with highest temperatures during July and August (Figure 4). There was no statistically significant short-term difference at the five sites in summer (May – October) sea surface temperature values among years or sites (Table 5A, Figure 5A). Mean sea surface temperature for 2006, 2007 and 2008 was 15.91 + 0.63, 15.48 + 0.63 and 15.70 + 0.46 8 C (mean + SEM) respectively. Sea surface salinity values did not differ statistically among years (2006 – 2008) (Table 3B). The mean salinities for 2006, 2007 and 2008 were 15.63 + 1.44, 16.35 + 1.32 and 16.58 + 1.15 PSU (mean + SEM) respectively. As expected, mean summer salinity varied significantly among study sites (Table 5B), with significantly (SNK, P , 0.05) higher values at the northern sites Tj ̈rn ̈ and Kristineberg, and significantly (SKN, P , 0.05) lower values at the southern sites Lund ̊kra and H ̈llviken compared with H ̈gan ̈s (Figure 5B). No major Baltic inflows of high salinity water from the Skagerrak area occurred during the study period. However, a maximum salinity value of 18.3 PSU was measured at H ̈llviken in June 2008, which correlates with the only year that shipworms were found at Falsterbo (Figure 3B). The log- transformed yearly mean abundance of T. navalis at different sites did not correlate significantly to ...
Context 5
... abiotic determinants of species distributions, especially in estuarine and coastal ecosystems (Kinne, 1963; Bonsdorff, 2006; Ojaveer et al. , 2010). Previous studies have also implicated these factors in control- ling the distribution of shipworms (Scheltema & Truitt, 1954; Hoestland & Brasselet, 1968; Culliney, 1970; Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972; Saraswathy & Nair, 1974; Hoagland, 1986). Of about 65 described shipworm species (Turner, 1966), the widely distributed, euryhaline species Teredo navalis L. is the most investigated and the most abundant teredinid in Sweden (Norman, 1976, 1977). Teredo navalis broods its offspring until the larvae have reached straight-hinge stage, at which time the free-swimming larvae are released to the plankton, where they grow for a further 2 –5 weeks (Grave, 1928; Imai et al. , 1950; Loosanoff & Davis, 1963; Culliney, 1975). The species shows a wide tolerance to both temperature and salinity (reviewed in Nair & Saraswathy, 1971; Eckelbarger & Reish, 1972). Release of larvae can occur in salinities , 9 PSU and temperatures , 11 C 8 (Roch, 1940), although larvae are unable to survive at salinities less than 6– 7.5 PSU (M’Gonigle, 1926; Hoagland, 1986). The second member of Teredinidae recorded in Swedish waters is the oviparous species Psiloteredo megotara (Hanley). Little is known about this species’ biology and ecology. However, it shows higher growth rate, is less tolerant to low salinities, and is better adapted to low temperature than T. navalis (Dons, 1940; Norman, 1977). There is increasing concern that climate change will lead to shifts in the geographic ranges of ecologically and economic- ally important species. Several studies report range shifts due to climate change in terrestrial and marine species (e.g. Perry et al. , 2005: Harley et al. , 2006; Parmesan, 2006; Wernberg et al. , 2011), and changing distribution patterns of shipworms have also been reported recently (Sordyl et al. , 1998; Tuente et al. , 2002; Borges et al. , 2010, 2014). At the beginning of the 21st century rumours circulated about possible range-expansion of shipworms in Scandinavian waters: Swedish harbour authorities noticed an increased level of shipworm attacks on wooden constructions (Port of Gothenburg personal communication, Schlyter, 2009), and during the summer of 2002 shipworms were observed for the first time on the Danish island of Bornholm (Olsen, 2003). Shortly thereafter, marine archaeologists began to raise concerns over the risk of shipworms spreading into the Baltic Sea, a brackish water area with many valuable and well- preserved wooden wrecks (Olsson, 2006). Hypotheses of range expansion are perhaps most easily tested by comparing new range records with historical distribution data. We used a 35-year-old investigation of the geographical distribution of shipworms in Swedish waters as a baseline (Norman, 1977). Norman (1977) found high fre- quencies of T. navalis along the Swedish west coast from close to the Norwegian border (Koster Islands) southwards to the entrance to the Sound at M ̈lle (Figure 1). Beyond this point abundances declined and the most southern point of shipworm recruitment was observed at Klagshamn. The second species, P. megotara , was rare with very few specimens at some sites from the Koster islands down to M ̈lle. We repeated Norman’s (1977) study to assess whether shipworms have changed their range over the past 35 years. Furthermore, in order to explore whether any shifts in the range of shipworms could be correlated with temporal changes in environmental variables, we compared historical and present-day sea surface temperature and sea surface salinity data. We investigated occurrence of teredinids from the Skagerrak to the Baltic Sea (Figure 1). This region is a transitional area with complex hydrography and strong salinity gradients between the North Sea and Baltic Sea (Gustafsson & Stigebrandt, 1996). The oceanographic system is barotropi- cally driven mainly by differences in sea levels and wind patterns (Stigebrandt & Gustafsson, 2002). Large inflow of high saline water into the Baltic Sea through the Danish Straits and the Sound is limited by the topography and occurs only occasionally (Schinke & Matthaus, 1998). The dominant sea surface current is west along the Swedish south coast, and northbound along the Swedish west coast. However, daily variation occurs at local scales. Coastal sea surface temperature shows wide seasonal variation ( 2 4– 27 C 8 ) (http:// www.smhi.se). Sea surface salinity in the study area ranged from fully marine conditions in the Skagerrak ( . 30 PSU) down to brackish levels ( 7 PSU) along the southern coast of Sweden and around Bornholm (). The study was conducted along the Swedish west and south coasts and around the Danish island of Bornholm during 2006 – 2008. In 2006, the distribution of shipworms was investigated at 9 sites that partly followed the sites investigated in Norman (1977) (Figure 1). In order to increase spatial reso- lution of the investigation, and to study a possible range expansion of shipworm infestations in the Baltic Sea, five additional harbours along the Swedish coast, and four additional harbours around Bornholm, Denmark, were also included in 2007 and 2008 survey (Figure 1). At each site, four unplaned pine ( Pinus sylvestris ) panels (25 × 75 × 200 mm) were submerged at a depth of 0.5–2 m below sea surface in the spring of each year. Holes (ø 25 mm) were drilled in the centre of the panels, the panels attached to a polypropylene rope with cable ties, and then suspended vertically in the water. Panels were collected one year later, surface fouling organisms were removed, and the panels were stored in the freezer ( 2 20 8 C). In order to esti- mate the shipworm abundance, panels were analysed by X-ray radiography (Siemens – Elema Mobilett II 40 kV and 14 mA). Before X-ray, panels were thawed and dried at room temperature for 48 h. The number of shells visible was counted over the whole X-ray photo area, and abundance (per dm 2 ) calculated for the exposed surface of the panel (4.275 dm 2 per panel). Yearly mean values of T. navalis abundance (individuals dm 2 2 ) at each site were calculated and analysed in a 2-way analysis of variance (ANOVA) with Decade as a 2-level, and Site as a 9-level, fixed factor. Data from 2006 –2008 were analysed in two separate statistical tests due to lost wooden panels at some sites in 2006 and extension of sites in 2007 and 2008. The abundance data from 2006 were statistically analysed in a one-way ANOVA with Site as a fixed 9-level factor. The abundance data from 2007 and 2008 were statistically analysed in a two-way ANOVA with Year as a 2-level random factor and Site as a 17-level fixed factor. Means were compared using the Student-Newman-Keuls (SNK) procedure (Underwood, 1997). All data were tested for homogeneity of variances with Cochran’s test (Underwood, 1997). The abundance of P. megotara was very low during both study periods with only a few observations of single individuals, and therefore no statistical analysis of these data was performed. Sea surface temperature and salinity data along the Swedish west and south coast were analysed for the summer period (May to October – the season for adult T. navalis reproduction and larval metamorphosis). Data were obtained from the Swedish Meteorological and Hydrological Institute (). Additional salinity and temperature data were also obtained from the marine biological stations at Kristineberg and Tj ̈rn ̈ (, Figure 1). In order to investigate a possible long-term change in sea surface temperature from the 1970s to the 2000s, 3 daily averages of temperature data were extracted from Kristineberg (handwritten logbook and ) each month during the study season (May –October) from 1971 – 1973 and 2006–2008. Long-term high-resolution temperature data were only available for Kristineberg and therefore possible changes in sea surface temperature at this site were assumed to be representative for the whole study area. Data were analysed statistically using a mixed model ANOVA with Decade as a 2-level fixed factor, Year as a 3-level random factor nested within Decade, and Month as a 6-level fixed factor. In order to investigate possible short-term changes in sea surface temperature and salinity along the Swedish west coast during the study period (2006 – 2008), data were extracted from monitoring stations (H ̈gan ̈s, Lund ̊kra and H ̈llviken) close to sampling sites in the Sound (M ̈lle, Barseb ̈ckshamn and Faslterbo) (), as well as from Kristineberg () and Tj ̈rn ̈ ( Data were analysed using 2-way ANOVAs with Year as a 3-level random factor and Site as a 5-level fixed factor. In order to investigate if the abundance of T. navalis was correlated to the environmental variables, yearly mean values for 2006 – 2008 at different sites (Tj ̈rn ̈, Kristineberg, M ̈lle/H ̈gan ̈s, Barseb ̈ckshamn/Lund ̊kra and Falsterbo/H ̈llviken) were calculated, log-transformed and compared with sea surface temperature and salinity data using simple linear regression. No evidence for range expansion of T. navalis along the Swedish coast between the 1970s and the 2000s was detected (Figures 2 & 3), although we found one individual at Falsterbo, a site that was not investigated in the 1970s (Figure 3B). However, we found a statistically significant interaction between the effects of Decade and Site on shipworm abundance (Table 1). The mean abundance of T. navalis at one site (Arild) was significantly (SNK, P , 0.05) higher in samples from the 2000s (Figure 2). There were no statistically significant differences in shipworm abundances at the other sites (SNK, P . 0.05), although at Barseb ̈ckshamn, T. navalis was only observed in the 2000s (Figure 2). The presence of P. megotara was similar during the two periods with observations of single individuals at Tj ̈rn ̈, Kristineberg, Tr ̈sl ̈vsl ...
Citations
... Among the abiotic environmental factors that regulate the distribution and abundance of their populations, salinity and temperature are the most important (Hoagland, 1986;Appelqvist and Havenhand, 2016;Appelqvist et al., 2015;Borges et al., 2014;Maldonado et al., 2020). Dissolved oxygen is also a relevant factor that restricts populations, particularly in those species that inhabit deeper waters (Laurent et al., 2013). ...
Teredinid bivalves (shipworms) are the main wood degraders in marine environments. However, little is known about the biological interactions between these marine wood borers and wood-associated biofouling species. Filter-feeding species and seaweeds are frequent biofoulers on the submerged wood. Using the marine xylophagous bivalve Bankia martensi (Stempell, 1899) as a model, we hypothesized that increasing the abundance of biofouling species on wood will decrease the recruitment and subsequent growth of the shipworm B. martensi. During the springs of 2020 and 2021, experiments manipulating biofouling cover were carried out using pine panels in Bahía Metri, southern Chile. Three experimental levels of biofouling cover were established (low: 0%–10%, intermediate: 40%–50%, and high: 90%–100%). After five months, the number of B. martensi perforations (as proxy as larval settlement density) and specimen sizes (length, width and volume) in the panels were measured. An inverse relationship between the perforation densities of B. martensi and biofouling cover on the wooden panels was observed. The most frequent biofouling species were mussels and seaweeds which tended to settle on the upper and lateral surfaces, while acorn barnacles and bryozoans were more frequent on the lower surface. Bankia martensi perforations were reduced with increasing biofouling cover. The number of perforations varied according to the panel surface, higher density on the upper and lateral surfaces and lower on the underside. Bankia martensi specimens were larger, both in length and in volume, in panels with low biofouling compared to intermediate and high biofouling cover, while width did not vary with treatment. Our results suggest that the biofouling cover decreases B. martensi recruitment and growth rates, which in turn reduces the wood degradation rate caused by this teredinid. Future manipulative experiments with selected biofouling species (filter-feeders, such as mussels and barnacles), as well as incorporating measurements of reproductive traits of shipworms could help in understanding the biological interactions between these marine communities of wood-boring and biofouling species.
... Distribution and abundance of shipworm is insufficient all around the world with only few studies conducted. Study of Beasly et al. (2005); Filho et al. (2008) was conducted in Brazil, Appelqvist et al. (2015) was in Sweden, Paalvast and Velde (2011) was in Netherlands, and Velásquez and Shipway (2018) was in the Southwest Pacific. In Malaysia, there were several studies on shipworms that had been conducted in the past. ...
Highlight ResearchRedescription of marine woodborers, Bactronophorus thoracites and Bankia gracilis from the region were illustrated.New records of Bactronophorus thoracites and Bankia gracilis from the region.Addition info on the measurements of pallets was recorded.Certain ecological data on the habitat of marine woodborers Bactronophorus thoracites and Bankia gracilis were documented.AbstractMollusc wood-borers are classified into two groups: pholads and teredinids. While pholads have a limited distribution to temperate and tropical marine waters, teredinids are found worldwide. However, limited info on the taxonomy was documented on the marine wood borer in Sabah, Malaysia. Present study focuses on determining the wood borer species from Sabah waters, Malaysia. Samples were collected from fallen tree debris in the mangrove at Kota Kinabalu, Kuala Penyu and W.P. Labuan during low tide and water quality parameters were taken in-situ from all three sampling sites. Specimen identification was carried out by observing the physical characteristics of the pallets which are unique between genuses. The species Bactronophorus thoracites was identified from the Kota Kinabalu sampling site and species Bankia gracilis were found in both the Kuala Penyu and W.P. Labuan sampling site. The pallet of B. thoracite are of “dagger-and-sheath” shape, it is 26mm in length, with blade measuring 10mm in length, basal cup 4mm in length and stalk 12mm in length. The pallet of B.gracilis is characterized by the dark periostacum covering the 3-lobbed upper margin of the calcareous portion of the inner face of the cone, the pallet is 20mm in length, with the blade and stalk both measuring 10mm in length. The present study described two species of marine wood borers namely B. thoracites and B. gracilis in Sabah and W.P. Labuan with some measurement metrics and ecological parameters that were missing from previous studies that aided the process of species identification in future.
... The spread of shipworms continued even after the end of the era of galleons colonizing new seas all-over the world (Wolff 2005;Borges et al. 2014a;Shipway et al. 2014;Appelqvist et al. 2015a;Velásquez and López 2015) and consequently the geographic origin of many shipworm species is questionable. ...
During almost a century of permanence in the Mediterranean, the warm water species Teredo bartschi has adapted to progressively colder climates up to overwintering at water temperatures only a few
degrees above zero. A fine-grained analysis of discoveries, synonyms, museum collections and grey literature establishes that this species entered the Mediterranean since at least 1935. Coming from tropical waters through the Suez Canal, the species has undergone to a long period of acclimatization in the Levantine Basin of the Mediterranean and then pushed north at the beginning of this century until it has invaded the Lagoon of Venice. The invasion routes are reconstructed and presented. The lagoon of Venice is a microtidal bar-built estuary located in the northernmost part of the Mediterranean and represents the highest latitude reached by the species on a global scale. Here for over ten years, T. bartschi has now become invasive forming stable and abundant populations. This paper presents some biometrics of hard parts such as pallets and shells as well as the description of siphons, useful for the identification and characterization of the species. The shape of the pallets of the Venetian population differs from the Aqaba’s (Giordania) and Mersin’s (Turkey) populations.
Phenotypic variation are probably due to environmental effects on morphology.
... Genera of economic importance (due to the damage they cause) include Teredo, Bankia, and Lyrodus (Treu et al. 2019). Shipworms can be found in almost all oceanic (saline) waters, and more recently also in the Baltic Sea, the world's largest inland brackish sea, due to increasing salinity (Leppäkoski et al. 2002, Borges et al. 2014, Appelqvist et al. 2015. Bivalve mollusc species belonging to the family Xylophagaidae and Pholadidae are also of economic importance outside of European oceanic waters (Treu et al. 2019). ...
Factors relevant to degradation are important in every wood application. For wood used in ground and water contact; well documented abiotic factors (or agents) include exposure to temperature and moisture linked to the physiological requirements of biotic degradation agents such as wood-decaying fungi and bacteria. Other biotic degradation agents such as subterranean insects and marine borers occur overshadowing the effect of fungal and bacterial decay, but are restricted in geographical distribution and to aquatic applications, respectively. This review focusses on decay specific to soil exposure. The inherent material characteristics are important to durability in that heartwood and sapwood show differences in resistance to degradation between species, provenance, and individual trees. Wood durability testing methods and classification, as well as a summary of prominent models and variables suitable for regional-level modelling of in-ground wood durability are presented.
... A decreased abundance of teredinids towards the Southern part of Sweden's West coast was found. The hypothesis of shipworms having expanded their range into the Baltic Sea could not be proven (Appelqvist et al. 2014;Appelqvist 2015). ...
... These factors mainly include the abiotic ones, such as temperature and water salinity, as well as ice conditions. While no evidence of the invasion of the Baltic Sea by teredinid recruits was found on the Swedish coast (Appelqvist et al. 2014), it is reported that shipworm is spreading within the Southern part of the Baltic Sea, leading to severe problems and economic damages in Denmark, Germany, Poland, and Southern Sweden (Sordyl et al. 1998;Borges et al. 2014b;Lippert et al. 2017). While the abundance of Teredo navalis was positively correlated to the surface water salinity, no positive correlation to temperature could be shown. ...
... A decreased abundance of teredinids towards the Southern part of Sweden's West coast was found. The hypothesis of shipworms having expanded their range into the Baltic Sea could not be proven (Appelqvist et al. 2014;Appelqvist 2015). ...
... These factors mainly include the abiotic ones, such as temperature and water salinity, as well as ice conditions. While no evidence of the invasion of the Baltic Sea by teredinid recruits was found on the Swedish coast (Appelqvist et al. 2014), it is reported that shipworm is spreading within the Southern part of the Baltic Sea, leading to severe problems and economic damages in Denmark, Germany, Poland, and Southern Sweden (Sordyl et al. 1998;Borges et al. 2014b;Lippert et al. 2017). While the abundance of Teredo navalis was positively correlated to the surface water salinity, no positive correlation to temperature could be shown. ...
Timber structures in marine applications are often exposed to severe degradation conditions caused by mechanical loads and wood-degrading organisms. This paper presents the use of timber in marine environments in Europe from a wood protection perspective. It discusses the use of wood in coastline protection and archeological marine wood, reviews the marine borer taxa in European waters, and gives an overview of potential solutions for protection of timber in marine environments. Information was compiled from the most relevant literature sources with an emphasis on new wood protection methods; the need for research and potential solutions are discussed. Traditionally, timber has been extensively utilized in a variety of marine applications. Although there is a strong need for developing new protection systems for timber in marine applications, the research in this field has been scarce for many years. New attempts to protect timber used in marine environments in Europe have mainly focused on wood modification and the use of mechanical barriers to prevent colonization of marine wood borers. The importance of understanding the mechanisms of settlement, migration, boring, and digestion of the degrading organisms is key for developing effective systems for protecting timber in marine environments.
... A decreased abundance of teredinids towards the Southern part of Sweden's West coast was found. The hypothesis of shipworms having expanded their range into the Baltic Sea could not be proven (Appelqvist et al. 2014;Appelqvist 2015). ...
... These factors mainly include the abiotic ones, such as temperature and water salinity, as well as ice conditions. While no evidence of the invasion of the Baltic Sea by teredinid recruits was found on the Swedish coast (Appelqvist et al. 2014), it is reported that shipworm is spreading within the Southern part of the Baltic Sea, leading to severe problems and economic damages in Denmark, Germany, Poland, and Southern Sweden (Sordyl et al. 1998;Borges et al. 2014b;Lippert et al. 2017). While the abundance of Teredo navalis was positively correlated to the surface water salinity, no positive correlation to temperature could be shown. ...
Timber structures in marine applications are often exposed to severe degradation conditions caused by mechanical loads and wood-degrading organisms. This paper presents the use of timber in marine environments in Europe from a wood protection perspective. It discusses the use of wood in coastline protection and archeological marine wood, reviews the marine borer taxa in European waters, and gives an overview of potential solutions for protection of timber in marine environments. Information was compiled from the most relevant literature sources with an emphasis on new wood protection methods; the need for research and potential solutions are discussed. Traditionally, timber has been extensively utilized in a variety of marine applications. Although there is a strong need for developing new protection systems for timber in marine applications, the research in this field has been scarce for many years. New attempts to protect timber used in marine environments in Europe have mainly focused on wood modification and the use of mechanical barriers to prevent colonization of marine wood borers. The importance of understanding the mechanisms of settlement, migration, boring, and digestion of the degrading organisms is key for developing effective systems for protecting timber in marine environments.
... Psiloteredo megotara was described by Hanley in Forbes and Hanley (1848) from England. This coldwater species has been reported mainly from the eastern North Atlantic, occurring infrequently in test panels and maritime structures ( Norman 1977;Appelqvist et al. 2015), except in Trondheim Fjord, Norway, where it is the most common shipworm ( Santhakumaran and Sneli 1978;Santhakumaran and Sneli 1984;Borges et al. 2014). P. megotara has been reported occasionally along the Atlantic coast of North America ( Berg et al. 1987), with a more consistent presence in offshore waters ( Brown 1953;Wallour 1960). ...
The family Teredinidae (shipworms) contains 70-plus species of boring bivalves specialized to live in and digest wood. Traditional means of species identification and taxonomy of this group encounter numerous challenges, often compounded by the diverse and dynamic nature of shipworm ecology and distribution. Modern integrative taxonomic methods are shedding new light on this complex group, from delineating cryptic species to resolving phylogenetic relationships within the family. This study reported new sequence data from shipworm species rafted from the western to eastern Pacific Ocean in woody marine debris resulting from the Japanese tsunami of 2011. Eight species of shipworms were found in this debris and tissue from five species was collected. Partial nuclear ribosomal 18S rRNA gene sequences were obtained from Bankia bipennata (Turton, 1819), Bankia carinata (Gray, 1827), Psiloteredo sp., Teredora princesae (Sivickis, 1928), and Teredothyra smithi (Bartsch, 1927). A 658 base pair fragment of COI was successfully sequenced from Psiloteredo sp. and T. princesae specimens from tsunami debris, as well as Psiloteredo megotara (Hanley, 1848) from Europe and Nototeredo norvagica (Spangler, 1792) from Scandinavia. Psiloteredo sp. is very similar morphologically to the North Atlantic Ocean P. megotara; however, these two species are genetically distinct with a 12.8% K2P distance in their COI sequences. The transport of shipworms across the North Pacific Ocean in woody debris generated by a tsunami shows that major geologic events can connect previously isolated geographic areas and provide the opportunity for the establishment of invasive species and subsequent speciation.
... Maximum numbers of boreholes in the study years were between 990 (2013) and 90 (2015) boreholes per dm 2 . Kristensen (1979) found a maximum of 27 juvenile T. navalis per dm 2 in Danish waters, and Norman (1977a,b) and Appelqvist et al. (2015b) between 100 and 200 individuals per dm 2 , respectively, on the Swedish west coast. However, in these studies juvenile individuals were counted using x-ray radiography, in contrast to the present study, in which boreholes were counted. ...
Wooden groin systems on the southwestern Baltic Sea coast are a traditional and important coastal-protection facility, but have been regularly infested and destroyed by the wood-boring bivalve Teredo navalis since the early 1990s. The occurrence of T. navalis was presumed to be limited mainly by the prevailing low salinities. Recently, a possible range expansion of this invasive species to the more eastern parts of the Baltic Sea has been discussed. T. navalis larval settlement was therefore monitored at the distribution boundary of the species in the Baltic Sea over a period of 4 years. At 7 stations along the prevailing salinity gradient on the Mecklenburg-western Pomeranian coast, larval traps were installed at regular time intervals, while at the same time water temperature and salinity were measured continuously every hour. Correlations between measured abiotic parameters and borehole abundance of T. navalis were tested. For the German Baltic Sea coast, no range expansion of T. navalis was confirmed. The salinity and temperatures at the groin systems varied among the study years, and significant correlations between T. navalis borehole abundance and salinity as well as temperature were found. Higher summer temperatures favor the T. navalis borehole abundance on the Mecklenburg-western Pomeranian coast, and may slightly shift the distribution border of this species toward lower salinities.
... This could be an indication for a high genetic diversity which might be reflected by high abundances. Up to 700 animals per dm 2 have been observed in pine wood panels during the investigation period (own unpublished data), which is quite high compared to other regions like the Kattegat (Appelqvist et al., 2015b). Moreover, the network analyses of both datasets revealed no differentiated substructures or demes. ...
The first documented scientific reports of the common marine shipworm Teredo navalis (Bivalvia) for Central European waters date back to the time between 1700 and 1730 in the Netherlands. During the following centuries there were several irregular mass occurrences reported for both the North Sea and the Baltic Sea. These events were accompanied by massive destruction of wooden ships and coastal protection structures. In this study, the first population analysis of T. navalis is presented with the aim to detect the genetic population structure in the waters of Central Europe. The mtDNA COI (cytochrome c oxidase subunit I) locus was found as suitable molecular marker and hence a 675 bp gene fragment was studied. A total of 352 T. navalis specimens from 13 different sampling sites distributed across Central Europe were examined. Subsequently, various population genetic indices including FST values and an AMOVA analysis were applied for the description of the population structure. To visualize the distribution of haplotypes at the different sampling sites two median-joining networks were calculated. In addition, the past demographic structure of the T. navalis population was analyzed, among others by calculating Tajima's D, Fu's F and the mismatch distribution. Finally, all computations of the population genetic indices could not reveal differentiated populations or any kind of distinct population structure in T. navalis. The network analyses revealed “star-like” patterns without differentiated substructures or demes. Therefore, it can be assumed that a sudden expansion of this species took place without any indications of neither a bottleneck nor a founder effect for the study area. The results of this study support the concept of a regional panmictic population in the waters of Central Europe with unhindered migration of individuals (e.g., via pelagic larvae) between the various sampling sites as reflected by a high gene flow.
