Boletín de la Real Sociedad Española de Historia Natural. Sección biológica
In this paper we present a list of marine tardigrade species collected in the rías of O Barqueiro... more In this paper we present a list of marine tardigrade species collected in the rías of O Barqueiro and Foz (Galicia, NW. Iberian Peninsula) as a result of a widen project focused on its intertidal meiobenthos. As result of this work 10 tardigrade species were found, it is the first record for Orzeliscus belopus Du Bois-Reymond Marcus, 1952, one of the species listed, for the Iberian Peninsula, whereas Batillipes dicrocercus Pollock, 1970 and Batillipes phreaticus Renaud-Debyser, 1959 were recorded for first time in Galicia. Besides we showed the number of specimens found, some ecological notes and its geographical distribution, for each of species found. Finally, we compare the state-of-the-art about marine Tardigrada biodiversity in the Iberian Peninsula with other European countries.
Journal of Experimental Marine Biology and Ecology
Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-veg... more Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-vegetated habitats. In this study, intertidal annual macroalgae were used as model organisms to test the role of macroalgal morphology in driving the structure of their associated epifaunal assemblages. For this aim, 6 macroalgal species, apparently different in morphology, were sampled from two intertidal rocky shores to examine the effects of habitat morphology on the number of individuals, taxa richness and the structure of its associated epifaunal assemblages by means of univariate and multivariate techniques. To provide a complete overview of macroalgal morphology, biomass was used as a proxy of habitat quantity and fractal measures as proxies of habitat complexity. Results showed that almost all the studied pairs of macroalgae showed significant differences at least for one of the morphological measures used. Moreover, epifaunal assemblages showed significant differences between macro...
Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is ... more Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is an invasive macroalga widely distributed along the Atlantic Iberian Peninsula. Despite being quite abundant from Norway to South Portugal, there is little information about its patterns of distribution, particularly at a large spatial scale (i.e. thousands of kilometres). Here, we examined the spatial variation in the invasion success of S. muticum from rockpools at multiple spatial scales using a hierarchical design. In addition, we analysed how the richness of native assemblages was related to its invasion success and how this relationship changed over different scales. Most of the variation in the invasion success was found at the smallest scales of pool and plot. Furthermore, the invasibility of native macroalgal assemblages was related to the native species richness, but causes that determined invasion success could not be separated from the effects provoked by the invader. Results suggest that small-scale (centimetres to metres) processes contribute considerably to the heterogeneity of S. muticum invasion success.
Journal of Experimental Marine Biology and Ecology, 2015
ABSTRACT The attributes and traits of populations of intertidal invertebrates can become modified... more ABSTRACT The attributes and traits of populations of intertidal invertebrates can become modified in response of the environmental pressures. Therefore, comparative studies of biological traits of range-edge populations versus non range-edge ones may provide essential insights into what processes determine their geographical distribution. In recent decades, the range of Siphonaria pectinata has expanded northwards on the Atlantic coast of the Iberian Peninsula, overlapped in time with significant changes in the sea surface temperature owing to weaker upwelling events. The main objective of this study was to explore differences in the traits and attributes between non range-edge and range-edge populations of S. pectinata and the potential role of temperature in shaping these populations as well. For these aims different biological traits were measured for a year in two non range-edge populations and two range-edge populations of S. pectinata. In general, non range-edge populations had higher densities and percentage of juveniles during November and smaller sizes than range-edge populations. The lack of significant differences in the reproductive traits between the two types of populations and the greater egg-ribbon lengths in range-edge populations suggests a high mortality of larvae or settled juveniles in the latter. Larval and juvenile stages are the most vulnerable stage of the life cycle of marine organisms and temperatures close to the tolerance limit may induce stress. Therefore, it is likely that lower water and air temperatures in the north could be responsible for the higher larval or juvenile mortality in range-edge populations of S. pectinata.
Meiofauna vertical distribution knowledge is important to improve the ecological understanding of... more Meiofauna vertical distribution knowledge is important to improve the ecological understanding of meiobenthic communities. However, most works are usually limited to single taxa or to a sedimentary type or environment. In this work total meiofauna and main taxa vertical distribution were studied considering two depth scales: 5 cm intervals up to 20 cm depth and 1 cm intervals up to 10 cm depth. These samples were collected at three sedimentary types: medium sands, fine sands and muddy sands; from two Galician rias (NW Iberian Peninsula). Results pointed out a general trend, with maximum densities within the first 5 cm then declining with depth but sediment grain size seriously influenced vertical distribution, showing a drop in density at finer sediments. Moreover, copepods and ostracodes were more restricted to the sand surface than nematodes, gastrotrichs and turbellarians probably due to the different sensitivity to low oxygen levels. Vertical distribution within the first 10 cm,...
After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid ... more After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.
Habitat structure is a primary factor determining the organism distribution. Here, two native and... more Habitat structure is a primary factor determining the organism distribution. Here, two native and one invasive macroalgal species, apparently different in morphology, were sampled to examine the effects of habitat complexity on the abundance (N), taxon richness (S) and structure of their associated epifaunal assemblages by means of univariate and multivariate techniques. Dry weight and fractal measures were used as proxies of habitat quantity and habitat architecture respectively. Results revealed significant differences in the complexity and in N, S and the structure of epifaunal assemblages among macroalgae and significant correlations between complexity and epifauna. Results suggested that, beside the effect of habitat quantity, the habitat architecture also seems to play a significant role in shaping epifaunal assemblages. Complexity of the studied invasive macroalga significantly differed from that of native species and hosted also different assemblages. Therefore, our findings suggest that invasive macroalgae, if structurally different from native species, induce changes in the associated epifauna.
in coastal seawaters and soft tissues of macroalga Fucus spiralis from the northwest coast of Por... more in coastal seawaters and soft tissues of macroalga Fucus spiralis from the northwest coast of Portugal were determined to assess spatial variations of metal bioavailabilities and bioaccumulation factors to compare different ecological quality classifications. Both coastal seawaters and soft tissues of F. spiralis showed significant spatial variations in their metal concentrations along the coast. The macroalgae F. spiralis accumulated more efficiently Cd, Mn and Zn and showed low bioaccumulation factors to Cr, Cu and Fe. Regarding the metal guidelines of the Norwegian Pollution Control Authority, the entire northwest (NW) coast of Portugal in April 2013 should be classified as 'class I-unpolluted' for all metals, except in Ave for Cu ('class II-moderately polluted') and Cavado for Cd and Cu ('class II-moderately polluted'), revealing the low metal bioavailabilities of these seawaters. As there were always significant positive correlations between all metals in seawaters and F. spiralis, this macroalga species was considered a suitable monitoring tool of metal contamination in the NW coast of Portugal and a useful aquatic organism to be included in the European Environmental Specimen Banks in order to establish a real-time environmental monitoring network under the European Water Framework Directives.
We investigated effects of subtle nutrient enrichment and metal pollution on different levels of ... more We investigated effects of subtle nutrient enrichment and metal pollution on different levels of biological organization (i.e. whole assemblage, population and individual) of species-rich assemblages. We used rockpools as model system, applying a multi-factorial sampling design to test hypotheses on differences between disturbed and reference locations. Results indicated that disturbed and reference locations supported similar assemblages, as well as individual fitness-related life-traits were ineffective to discriminate between the two conditions. In contrast, assemblages responded to pollution through a reduction of the abundance of sensitive species and a proliferation of tolerant species, although these alterations were detectable only once the influence of dominant taxa was down-weighed by data transformation. Present findings suggest that, contrarily to individual level variables, assemblage structure after data transformation and patterns of distribution and abundance of differently sensitive taxa would be a powerful tool to detect effects of subtle pollution on species-rich assemblages.
Benthic investigations at the Azores archipelago revealed the presence of two species of the poly... more Benthic investigations at the Azores archipelago revealed the presence of two species of the polychaete genus Pisione, namely P. remota and P. guanche. The identification of the latter was confirmed after comparison with the type series and is herein reported for the first time from the Azores. Specimens of P. guanche are described and additional morphological observations are presented.
Journal of the Marine Biological Association of the United Kingdom, 2012
The northern Galician rias provide important economic and social services from fisheries, shellfi... more The northern Galician rias provide important economic and social services from fisheries, shellfish harvesting and recreational activities. Consequently, these rias have been included in the Nature 2000 Network as a Special Conservation Zone. The aims of this study were to describe the meiofauna spatial structure in terms of diversity and abundance of major taxa, as well as its relationship with the environmental characteristics in the Ria de Foz nature reserve. For this aim, environmental gradients and distribution patterns of intertidal meiobenthic communities at the Ria de Foz nature reserve were studied using multivariate methods. Ria de Foz showed to be a complex transitional habitat with significant changes in its environment along the estuarine gradient. An abundant and rich meiofauna community was reported at Ria de Foz. A total of 21 higher taxa of meiofauna were found. The most common taxa were nematodes, copepods, ostracods and turbellarians. Three clear different meiobenthic communities were defined. These three communities showed a clear spatial distribution pattern along the estuarine gradient. Moreover, a high degree of similarity between distribution patterns of meiobenthic communities and previously studied macrobenthic communities was found. Regarding the role of environmental factors shaping meiobenthic community distribution patterns distance to the river mouth was the environmental variable that best explained meiobenthic community structure and distribution. Therefore, changes on hydrodynamics that affect environmental factors related to the estuarine gradient will change the distribution pattern and diversity of benthic communities. This work provides the first information about meiobenthos diversity and structure in the Ria de Foz nature reserve and should be useful for future management and conservation plans on this and other similar protected areas.
The effect of polycyclic aromatic hydrocarbons (PAHs) on Galician sandy beach ecosystems, six mon... more The effect of polycyclic aromatic hydrocarbons (PAHs) on Galician sandy beach ecosystems, six months after the Prestige oil spill, was evaluated using the meiobenthos at a higher taxon level as an indicator. Meiobenthos community structure, environmental variables and sediment PAH content from six affected exposed beaches were studied and compared with three reference sites. They were also compared with data from polluted beaches obtained during the first days of the spill. Significant amounts of PAHs were found in affected beach sediments and both univariate and multivariate analyses showed differences between affected and reference beaches. Correlation analyses between PAH content and the meiobenthos community structure showed that 1,2-dimethylnaphthalene (C2-NAPH) and 1-methylphenanthrene (C-PHEN) affected both the community structure and the abundance of the main taxa. These two PAHs seem to be responsible for the low meiofauna density values, which suggests that there is a relationship between the oil spill and the differences between affected and reference localities.
The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community stru... more The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community structure at higher levels of taxonomic aggregation. In addition, the relationship between sediment individual polycyclic aromatic hydrocarbon (PAH) concentration and meiofauna community structure was investigated. Six months after the Prestige oil spill, meiobenthos community and sediment PAHs content from seven shallow subtidal localities along the Galician coast were studied. Two sites presented differences in community structure, characterized by high densities of nematodes, gastrotrichs and turbellarians, and low densities of copepods. Chrysene and triphenylene were only found at these two disturbed sites and could be responsible for differences of meiobenthos community structure. However, differences in community structure of sites could be linked with sedimentary parameters, and discrimination between the effect of PAHs and sedimentary parameters was impossible due to the lack of baseline studies on meiobenthos and PAHs contents in this area.
Ecosystem engineers such as mussels may affect strongly both the structure of benthic assemblages... more Ecosystem engineers such as mussels may affect strongly both the structure of benthic assemblages and the ecosystem functioning. The black-pygmy mussel Limnoperna securis is an invasive species that is spreading along the Galician coast (NW Spain). Its current distribution overlaps with the distribution of the commercial native mussel species Mytilus galloprovincialis, but only in the inner part of two southern Galician rias. Here, we analysed the assemblages associated with clumps of the two mussel species and evaluated if the invasive species increased complexity of habitat. To measure complexity of clumps we used a new method modified from the "chain and tape" method. Results showed that the identity of the mussel influenced macrofaunal assemblages, but not meiofauna. L. securis increased the complexity of clumps, and such complexity explained a high percentage of variability of macrofauna. The shift in dominance from M. galloprovincialis to L. securis may alter habitat structure and complexity, affecting the macrofaunal assemblages with unpredictable consequences on trophic web relations.
Macroalgae are useful organisms to monitor the environmental quality and to detect impacts due to... more Macroalgae are useful organisms to monitor the environmental quality and to detect impacts due to anthropogenic activities. However, it is very important to identify the scales of variation in natural assemblages, particularly for the detection of environmental impacts. Otherwise, changes due to anthropogenic impacts may be confused with differences due to natural temporal variability. Another important task is to determine the appropriate level of taxonomical effort needed to detect changes in the assemblage structure. Many taxonomical surrogates, at higher taxonomic levels than that of species, have been proposed but, the consistence in space and time of the results produced by surrogates with those obtained at specific level should be tested. The objectives of this study are to identify the seasonal patterns of tidepool macroalgal communities using objective procedures and to test the consistence between the patterns obtained considering data at the species level and functional groups. Results showed that the seasonal pattern obtained using functional groups and species was consistent. Tidepool macroalgal assemblages showed a seasonal pattern with significant differences between spring-summer and autumn-winter. This pattern can be explained by changes in environmental variables and the seasonal development of the dominating species. Ulva spp. and the non-indigenous species Grateloupia turuturu were the species responsible for this pattern due to their high seasonality in terms of biomass. Finally, the abundance and species diversity within the corticated functional group was proposed as indicator of environmental impacts due to its relatively constant abundance and its sensitivity to environmental impacts.
Boletín de la Real Sociedad Española de Historia Natural. Sección biológica
In this paper we present a list of marine tardigrade species collected in the rías of O Barqueiro... more In this paper we present a list of marine tardigrade species collected in the rías of O Barqueiro and Foz (Galicia, NW. Iberian Peninsula) as a result of a widen project focused on its intertidal meiobenthos. As result of this work 10 tardigrade species were found, it is the first record for Orzeliscus belopus Du Bois-Reymond Marcus, 1952, one of the species listed, for the Iberian Peninsula, whereas Batillipes dicrocercus Pollock, 1970 and Batillipes phreaticus Renaud-Debyser, 1959 were recorded for first time in Galicia. Besides we showed the number of specimens found, some ecological notes and its geographical distribution, for each of species found. Finally, we compare the state-of-the-art about marine Tardigrada biodiversity in the Iberian Peninsula with other European countries.
Journal of Experimental Marine Biology and Ecology
Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-veg... more Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-vegetated habitats. In this study, intertidal annual macroalgae were used as model organisms to test the role of macroalgal morphology in driving the structure of their associated epifaunal assemblages. For this aim, 6 macroalgal species, apparently different in morphology, were sampled from two intertidal rocky shores to examine the effects of habitat morphology on the number of individuals, taxa richness and the structure of its associated epifaunal assemblages by means of univariate and multivariate techniques. To provide a complete overview of macroalgal morphology, biomass was used as a proxy of habitat quantity and fractal measures as proxies of habitat complexity. Results showed that almost all the studied pairs of macroalgae showed significant differences at least for one of the morphological measures used. Moreover, epifaunal assemblages showed significant differences between macro...
Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is ... more Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is an invasive macroalga widely distributed along the Atlantic Iberian Peninsula. Despite being quite abundant from Norway to South Portugal, there is little information about its patterns of distribution, particularly at a large spatial scale (i.e. thousands of kilometres). Here, we examined the spatial variation in the invasion success of S. muticum from rockpools at multiple spatial scales using a hierarchical design. In addition, we analysed how the richness of native assemblages was related to its invasion success and how this relationship changed over different scales. Most of the variation in the invasion success was found at the smallest scales of pool and plot. Furthermore, the invasibility of native macroalgal assemblages was related to the native species richness, but causes that determined invasion success could not be separated from the effects provoked by the invader. Results suggest that small-scale (centimetres to metres) processes contribute considerably to the heterogeneity of S. muticum invasion success.
Journal of Experimental Marine Biology and Ecology, 2015
ABSTRACT The attributes and traits of populations of intertidal invertebrates can become modified... more ABSTRACT The attributes and traits of populations of intertidal invertebrates can become modified in response of the environmental pressures. Therefore, comparative studies of biological traits of range-edge populations versus non range-edge ones may provide essential insights into what processes determine their geographical distribution. In recent decades, the range of Siphonaria pectinata has expanded northwards on the Atlantic coast of the Iberian Peninsula, overlapped in time with significant changes in the sea surface temperature owing to weaker upwelling events. The main objective of this study was to explore differences in the traits and attributes between non range-edge and range-edge populations of S. pectinata and the potential role of temperature in shaping these populations as well. For these aims different biological traits were measured for a year in two non range-edge populations and two range-edge populations of S. pectinata. In general, non range-edge populations had higher densities and percentage of juveniles during November and smaller sizes than range-edge populations. The lack of significant differences in the reproductive traits between the two types of populations and the greater egg-ribbon lengths in range-edge populations suggests a high mortality of larvae or settled juveniles in the latter. Larval and juvenile stages are the most vulnerable stage of the life cycle of marine organisms and temperatures close to the tolerance limit may induce stress. Therefore, it is likely that lower water and air temperatures in the north could be responsible for the higher larval or juvenile mortality in range-edge populations of S. pectinata.
Meiofauna vertical distribution knowledge is important to improve the ecological understanding of... more Meiofauna vertical distribution knowledge is important to improve the ecological understanding of meiobenthic communities. However, most works are usually limited to single taxa or to a sedimentary type or environment. In this work total meiofauna and main taxa vertical distribution were studied considering two depth scales: 5 cm intervals up to 20 cm depth and 1 cm intervals up to 10 cm depth. These samples were collected at three sedimentary types: medium sands, fine sands and muddy sands; from two Galician rias (NW Iberian Peninsula). Results pointed out a general trend, with maximum densities within the first 5 cm then declining with depth but sediment grain size seriously influenced vertical distribution, showing a drop in density at finer sediments. Moreover, copepods and ostracodes were more restricted to the sand surface than nematodes, gastrotrichs and turbellarians probably due to the different sensitivity to low oxygen levels. Vertical distribution within the first 10 cm,...
After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid ... more After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.
Habitat structure is a primary factor determining the organism distribution. Here, two native and... more Habitat structure is a primary factor determining the organism distribution. Here, two native and one invasive macroalgal species, apparently different in morphology, were sampled to examine the effects of habitat complexity on the abundance (N), taxon richness (S) and structure of their associated epifaunal assemblages by means of univariate and multivariate techniques. Dry weight and fractal measures were used as proxies of habitat quantity and habitat architecture respectively. Results revealed significant differences in the complexity and in N, S and the structure of epifaunal assemblages among macroalgae and significant correlations between complexity and epifauna. Results suggested that, beside the effect of habitat quantity, the habitat architecture also seems to play a significant role in shaping epifaunal assemblages. Complexity of the studied invasive macroalga significantly differed from that of native species and hosted also different assemblages. Therefore, our findings suggest that invasive macroalgae, if structurally different from native species, induce changes in the associated epifauna.
in coastal seawaters and soft tissues of macroalga Fucus spiralis from the northwest coast of Por... more in coastal seawaters and soft tissues of macroalga Fucus spiralis from the northwest coast of Portugal were determined to assess spatial variations of metal bioavailabilities and bioaccumulation factors to compare different ecological quality classifications. Both coastal seawaters and soft tissues of F. spiralis showed significant spatial variations in their metal concentrations along the coast. The macroalgae F. spiralis accumulated more efficiently Cd, Mn and Zn and showed low bioaccumulation factors to Cr, Cu and Fe. Regarding the metal guidelines of the Norwegian Pollution Control Authority, the entire northwest (NW) coast of Portugal in April 2013 should be classified as 'class I-unpolluted' for all metals, except in Ave for Cu ('class II-moderately polluted') and Cavado for Cd and Cu ('class II-moderately polluted'), revealing the low metal bioavailabilities of these seawaters. As there were always significant positive correlations between all metals in seawaters and F. spiralis, this macroalga species was considered a suitable monitoring tool of metal contamination in the NW coast of Portugal and a useful aquatic organism to be included in the European Environmental Specimen Banks in order to establish a real-time environmental monitoring network under the European Water Framework Directives.
We investigated effects of subtle nutrient enrichment and metal pollution on different levels of ... more We investigated effects of subtle nutrient enrichment and metal pollution on different levels of biological organization (i.e. whole assemblage, population and individual) of species-rich assemblages. We used rockpools as model system, applying a multi-factorial sampling design to test hypotheses on differences between disturbed and reference locations. Results indicated that disturbed and reference locations supported similar assemblages, as well as individual fitness-related life-traits were ineffective to discriminate between the two conditions. In contrast, assemblages responded to pollution through a reduction of the abundance of sensitive species and a proliferation of tolerant species, although these alterations were detectable only once the influence of dominant taxa was down-weighed by data transformation. Present findings suggest that, contrarily to individual level variables, assemblage structure after data transformation and patterns of distribution and abundance of differently sensitive taxa would be a powerful tool to detect effects of subtle pollution on species-rich assemblages.
Benthic investigations at the Azores archipelago revealed the presence of two species of the poly... more Benthic investigations at the Azores archipelago revealed the presence of two species of the polychaete genus Pisione, namely P. remota and P. guanche. The identification of the latter was confirmed after comparison with the type series and is herein reported for the first time from the Azores. Specimens of P. guanche are described and additional morphological observations are presented.
Journal of the Marine Biological Association of the United Kingdom, 2012
The northern Galician rias provide important economic and social services from fisheries, shellfi... more The northern Galician rias provide important economic and social services from fisheries, shellfish harvesting and recreational activities. Consequently, these rias have been included in the Nature 2000 Network as a Special Conservation Zone. The aims of this study were to describe the meiofauna spatial structure in terms of diversity and abundance of major taxa, as well as its relationship with the environmental characteristics in the Ria de Foz nature reserve. For this aim, environmental gradients and distribution patterns of intertidal meiobenthic communities at the Ria de Foz nature reserve were studied using multivariate methods. Ria de Foz showed to be a complex transitional habitat with significant changes in its environment along the estuarine gradient. An abundant and rich meiofauna community was reported at Ria de Foz. A total of 21 higher taxa of meiofauna were found. The most common taxa were nematodes, copepods, ostracods and turbellarians. Three clear different meiobenthic communities were defined. These three communities showed a clear spatial distribution pattern along the estuarine gradient. Moreover, a high degree of similarity between distribution patterns of meiobenthic communities and previously studied macrobenthic communities was found. Regarding the role of environmental factors shaping meiobenthic community distribution patterns distance to the river mouth was the environmental variable that best explained meiobenthic community structure and distribution. Therefore, changes on hydrodynamics that affect environmental factors related to the estuarine gradient will change the distribution pattern and diversity of benthic communities. This work provides the first information about meiobenthos diversity and structure in the Ria de Foz nature reserve and should be useful for future management and conservation plans on this and other similar protected areas.
The effect of polycyclic aromatic hydrocarbons (PAHs) on Galician sandy beach ecosystems, six mon... more The effect of polycyclic aromatic hydrocarbons (PAHs) on Galician sandy beach ecosystems, six months after the Prestige oil spill, was evaluated using the meiobenthos at a higher taxon level as an indicator. Meiobenthos community structure, environmental variables and sediment PAH content from six affected exposed beaches were studied and compared with three reference sites. They were also compared with data from polluted beaches obtained during the first days of the spill. Significant amounts of PAHs were found in affected beach sediments and both univariate and multivariate analyses showed differences between affected and reference beaches. Correlation analyses between PAH content and the meiobenthos community structure showed that 1,2-dimethylnaphthalene (C2-NAPH) and 1-methylphenanthrene (C-PHEN) affected both the community structure and the abundance of the main taxa. These two PAHs seem to be responsible for the low meiofauna density values, which suggests that there is a relationship between the oil spill and the differences between affected and reference localities.
The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community stru... more The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community structure at higher levels of taxonomic aggregation. In addition, the relationship between sediment individual polycyclic aromatic hydrocarbon (PAH) concentration and meiofauna community structure was investigated. Six months after the Prestige oil spill, meiobenthos community and sediment PAHs content from seven shallow subtidal localities along the Galician coast were studied. Two sites presented differences in community structure, characterized by high densities of nematodes, gastrotrichs and turbellarians, and low densities of copepods. Chrysene and triphenylene were only found at these two disturbed sites and could be responsible for differences of meiobenthos community structure. However, differences in community structure of sites could be linked with sedimentary parameters, and discrimination between the effect of PAHs and sedimentary parameters was impossible due to the lack of baseline studies on meiobenthos and PAHs contents in this area.
Ecosystem engineers such as mussels may affect strongly both the structure of benthic assemblages... more Ecosystem engineers such as mussels may affect strongly both the structure of benthic assemblages and the ecosystem functioning. The black-pygmy mussel Limnoperna securis is an invasive species that is spreading along the Galician coast (NW Spain). Its current distribution overlaps with the distribution of the commercial native mussel species Mytilus galloprovincialis, but only in the inner part of two southern Galician rias. Here, we analysed the assemblages associated with clumps of the two mussel species and evaluated if the invasive species increased complexity of habitat. To measure complexity of clumps we used a new method modified from the "chain and tape" method. Results showed that the identity of the mussel influenced macrofaunal assemblages, but not meiofauna. L. securis increased the complexity of clumps, and such complexity explained a high percentage of variability of macrofauna. The shift in dominance from M. galloprovincialis to L. securis may alter habitat structure and complexity, affecting the macrofaunal assemblages with unpredictable consequences on trophic web relations.
Macroalgae are useful organisms to monitor the environmental quality and to detect impacts due to... more Macroalgae are useful organisms to monitor the environmental quality and to detect impacts due to anthropogenic activities. However, it is very important to identify the scales of variation in natural assemblages, particularly for the detection of environmental impacts. Otherwise, changes due to anthropogenic impacts may be confused with differences due to natural temporal variability. Another important task is to determine the appropriate level of taxonomical effort needed to detect changes in the assemblage structure. Many taxonomical surrogates, at higher taxonomic levels than that of species, have been proposed but, the consistence in space and time of the results produced by surrogates with those obtained at specific level should be tested. The objectives of this study are to identify the seasonal patterns of tidepool macroalgal communities using objective procedures and to test the consistence between the patterns obtained considering data at the species level and functional groups. Results showed that the seasonal pattern obtained using functional groups and species was consistent. Tidepool macroalgal assemblages showed a seasonal pattern with significant differences between spring-summer and autumn-winter. This pattern can be explained by changes in environmental variables and the seasonal development of the dominating species. Ulva spp. and the non-indigenous species Grateloupia turuturu were the species responsible for this pattern due to their high seasonality in terms of biomass. Finally, the abundance and species diversity within the corticated functional group was proposed as indicator of environmental impacts due to its relatively constant abundance and its sensitivity to environmental impacts.
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