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Jose M Riascos - One of the best experts on this subject based on the ideXlab platform.
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regulatory factors and structure of a component population of the spionid polydora bioccipitalis infesting the surf clam Mesodesma donacium
Journal of Aquatic Animal Health, 2011Co-Authors: Jose M Riascos, Miguel Cuturrufo, Aldo S Pacheco, Marcelo E OlivaAbstract:Abstract Spionidae, particularly polydorids, are common polychaete parasites of edible mollusks around the world. However, our understanding of the regulatory factors and population structure of these parasites is scant. In this study involving Polydora bioccipitalis and the surf clam Mesodesma donacium we evaluated (1) the environmental correlates of the prevalence and mean intensity of the infestation, (2) the relationship between the number of egg capsules and juvenile and adult parasites and the time elapsed since infestation, and (3) the spatial patterns of juveniles and adults within the host. Environmental factors showed no significant correlations with prevalence and mean intensity, suggesting that these factors do not act directly as regulators. Rather, storm surges seemingly induced clam stranding, which in turn affected both the prevalence and intensity of the infestation. The numbers of juveniles and egg capsules in blisters were significantly related to the time since infestation, suggesting ...
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environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range
Ices Journal of Marine Science, 2011Co-Authors: Jose M Riascos, Olaf Heilmayer, Marcelo E Oliva, Jurgen LaudienAbstract:Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833.Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Nino events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.
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long term parasitic association between the boring polychaete polydora bioccipitalis and Mesodesma donacium
Diseases of Aquatic Organisms, 2009Co-Authors: Jose M Riascos, Olaf Heilmayer, Jurgen Laudien, Marcelo E Oliva, Nury Guzman, Luc OrtliebAbstract:Polydora and related genera are common pests for molluscs. Establishing differences between native species and recent invaders provides the basis for understanding the effect of parasites and has implications for resource management. P. biocipitalis has been reported as a recently introduced species to the Chilean-Peruvian coast, raising concerns about its threat to native bivalve species. In contrast, studies on the infestation of P. bioccipitalis on the surf clam Mesodesma donacium, one of the most important species for shellfisheries, suggest a long-term parasitic relationship. The present study analyses infested (i.e. blistered) fossil shells of M. donacium deposited during the Holocene and Middle Pleistocene epochs and critically reviews evidence supporting the hypothesis of the recent introduction of P. bioccipitalis to the Chilean-Peruvian coast. The blistering pattern seen on fossil and recent shells can be considered species-specific for the infestation of M. donacium by P. bioccipitalis. No evidence was actually found on vectors, introduction pathways or distribution range to support the status of P. bioccipitalis as an introduced species. On the contrary, our findings point to a long-term association, at least for several hundred thousand years, between M. donacium and P. bioccipitalis.
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thriving and declining climate variability shaping life history and population persistence of Mesodesma donacium in the humboldt upwelling system
Marine Ecology Progress Series, 2009Co-Authors: Jose M Riascos, Wolf Arntz, Daniel Carstensen, Jurgen Laudien, Marcelo E Oliva, Andreas Guntner, Olaf HeilmayerAbstract:Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Nino episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Meso- desma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Nino) higher temperature and reduced salinity. Moreover, the repro- ductive spatial-temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (par- ticularly El Nino since at least the Holocene) has submitted this cold-water species to a continuous local extinction-recolonization process.
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infestation of the surf clam Mesodesma donacium by the spionid polychaete polydora bioccipitalis
Journal of Sea Research, 2008Co-Authors: Olaf Heilmayer, Jose M Riascos, Jurgen Laudien, Marcelo E Oliva, Wolf ArntzAbstract:The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Nino events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.
Olaf Heilmayer - One of the best experts on this subject based on the ideXlab platform.
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environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range
Ices Journal of Marine Science, 2011Co-Authors: Jose M Riascos, Olaf Heilmayer, Marcelo E Oliva, Jurgen LaudienAbstract:Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833.Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Nino events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.
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long term parasitic association between the boring polychaete polydora bioccipitalis and Mesodesma donacium
Diseases of Aquatic Organisms, 2009Co-Authors: Jose M Riascos, Olaf Heilmayer, Jurgen Laudien, Marcelo E Oliva, Nury Guzman, Luc OrtliebAbstract:Polydora and related genera are common pests for molluscs. Establishing differences between native species and recent invaders provides the basis for understanding the effect of parasites and has implications for resource management. P. biocipitalis has been reported as a recently introduced species to the Chilean-Peruvian coast, raising concerns about its threat to native bivalve species. In contrast, studies on the infestation of P. bioccipitalis on the surf clam Mesodesma donacium, one of the most important species for shellfisheries, suggest a long-term parasitic relationship. The present study analyses infested (i.e. blistered) fossil shells of M. donacium deposited during the Holocene and Middle Pleistocene epochs and critically reviews evidence supporting the hypothesis of the recent introduction of P. bioccipitalis to the Chilean-Peruvian coast. The blistering pattern seen on fossil and recent shells can be considered species-specific for the infestation of M. donacium by P. bioccipitalis. No evidence was actually found on vectors, introduction pathways or distribution range to support the status of P. bioccipitalis as an introduced species. On the contrary, our findings point to a long-term association, at least for several hundred thousand years, between M. donacium and P. bioccipitalis.
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thriving and declining climate variability shaping life history and population persistence of Mesodesma donacium in the humboldt upwelling system
Marine Ecology Progress Series, 2009Co-Authors: Jose M Riascos, Wolf Arntz, Daniel Carstensen, Jurgen Laudien, Marcelo E Oliva, Andreas Guntner, Olaf HeilmayerAbstract:Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Nino episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Meso- desma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Nino) higher temperature and reduced salinity. Moreover, the repro- ductive spatial-temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (par- ticularly El Nino since at least the Holocene) has submitted this cold-water species to a continuous local extinction-recolonization process.
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infestation of the surf clam Mesodesma donacium by the spionid polychaete polydora bioccipitalis
Journal of Sea Research, 2008Co-Authors: Olaf Heilmayer, Jose M Riascos, Jurgen Laudien, Marcelo E Oliva, Wolf ArntzAbstract:The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Nino events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.
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age related tolerance to osmotic stress implications for reproduction and recruitment ecology of Mesodesma donacium in the humboldt current ecosystem
EPIC3Physiomar 08 Physiological aspects of marine molluscs Brest France., 2008Co-Authors: Jose M Riascos, Daniel Carstensen, Jurgen Laudien, A Guentner, Olaf HeilmayerAbstract:The surf clam, Mesodesma donacium, is an ecologically and economically important species in sandy beach ecosystems of Chile and Peru. The massive mortality of this clam after strong El Nino events causes a significant reduction of the northern edge of geographic distribution, revealing a low ability to recover that might be related to reproduction and recruitment constraints. From an integrative data analysis comprising eight independent studies (including our own two-year data) revering to seven sandy beaches covering the entire geographic distribution, we determined the spatial-temporal patterns of the reproductive cycle and evaluated potential environmental factors explaining the observed patterns by using a multivariate analysis. During a one-month laboratory study we determined the effect of temperature (17.5, 23.5o C) and salinity(10, 20, 35 psu) on body condition, growth and mortality of this clam.The reproductive cycle of M. donacium showed a marked geographic pattern. Northern populations (16 - 32o S) showed an austral-spring spawning and southern (42 - 43o S) populations showed an austral-autumn spawning, with transitional populations in Mehuin (39o S), which exhibit a biannual, spring and autumn spawning seasons. Sea surface temperature variability showed a consistent seasonal latitudinal pattern, which could only explain the northern pattern of the reproductive cycle. In contrast, fresh-water input (river inflow and coastal precipitation) seems to explain better the observed pattern, as seasonality was not the same: pluvial, mixed and nival river regimes exhibit different seasonal patterns along latitude.A preliminary analysis showed that performance of M. donacium was not affected at low salinity (20 psu) but is negatively affected by extreme low salinity (10 psu) and anomalous high temperature (23.5o C). When analyzed by age groups, juveniles showed faster growth rates, higher body condition and lower mortality than adults at low salinities (10, 20 psu). They also seem to perform better than adults at anomalous high temperature. Although we used clams from the only place having apparently no influence of fresh-water input, M. donacium (notably juveniles) seems to be tolerant to osmotic stress. We discuss this finding and the fact that six out of seven of the studied populations are directly influenced by river inflow, as an adaptation of this species, to find suitable areas for settlement and recruitment. This is supported by previous observations showing that i) interspecific interactions play a critical role on the recruitment ecology of Mesodesma spp and Donax spp (species with a similar ecological role in sandy beaches); ii) M. donacium shows a definite spatial distribution pattern with age classes segregation along gradients of distance to river mouths and iii) former populations disappeared after closings of river input to the coastal zone. The availability of suitable places for settlement and recruitment may play a critical role in explaining the recovery ability of M. donacium after El Ninoty given the distribution of rivers flowing to the coast in Chile and Peru, with the Atacama dessert region acting as a geographic barrier to the northward distribution of this species.
Jurgen Laudien - One of the best experts on this subject based on the ideXlab platform.
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environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range
Ices Journal of Marine Science, 2011Co-Authors: Jose M Riascos, Olaf Heilmayer, Marcelo E Oliva, Jurgen LaudienAbstract:Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833.Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Nino events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.
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long term parasitic association between the boring polychaete polydora bioccipitalis and Mesodesma donacium
Diseases of Aquatic Organisms, 2009Co-Authors: Jose M Riascos, Olaf Heilmayer, Jurgen Laudien, Marcelo E Oliva, Nury Guzman, Luc OrtliebAbstract:Polydora and related genera are common pests for molluscs. Establishing differences between native species and recent invaders provides the basis for understanding the effect of parasites and has implications for resource management. P. biocipitalis has been reported as a recently introduced species to the Chilean-Peruvian coast, raising concerns about its threat to native bivalve species. In contrast, studies on the infestation of P. bioccipitalis on the surf clam Mesodesma donacium, one of the most important species for shellfisheries, suggest a long-term parasitic relationship. The present study analyses infested (i.e. blistered) fossil shells of M. donacium deposited during the Holocene and Middle Pleistocene epochs and critically reviews evidence supporting the hypothesis of the recent introduction of P. bioccipitalis to the Chilean-Peruvian coast. The blistering pattern seen on fossil and recent shells can be considered species-specific for the infestation of M. donacium by P. bioccipitalis. No evidence was actually found on vectors, introduction pathways or distribution range to support the status of P. bioccipitalis as an introduced species. On the contrary, our findings point to a long-term association, at least for several hundred thousand years, between M. donacium and P. bioccipitalis.
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thriving and declining climate variability shaping life history and population persistence of Mesodesma donacium in the humboldt upwelling system
Marine Ecology Progress Series, 2009Co-Authors: Jose M Riascos, Wolf Arntz, Daniel Carstensen, Jurgen Laudien, Marcelo E Oliva, Andreas Guntner, Olaf HeilmayerAbstract:Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Nino episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Meso- desma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Nino) higher temperature and reduced salinity. Moreover, the repro- ductive spatial-temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (par- ticularly El Nino since at least the Holocene) has submitted this cold-water species to a continuous local extinction-recolonization process.
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Reproductive cycle and gonad development of the Northern Argentinean Mesodesma mactroides (Bivalvia: Mesodesmatidae)
Helgoland Marine Research, 2009Co-Authors: Marko Herrmann, José E. F. Alfaya, Mauro L. Lepore, Pablo E. Penchaszadeh, Jurgen LaudienAbstract:The reproductive cycle and gonad development of the yellow clam Mesodesma mactroides was studied over a period of 24 months (January 2005–December 2006) at the Argentinean sandy beach Santa Teresita. Histological examination of gonadal tissue revealed that sex ratios did not significantly deviate from the proportion of 1:1 and no case of hermaphroditism was found. The reproductive cycle of M. mactroides followed an annual cyclicality, which was significantly correlated to monthly mean sea surface temperatures (SST). Oocytes showed highest abundance in winter, indicating a process of gonadal development and sexual maturation. The mean oocyte size decreased significantly during spring. Modal oocyte sizes decreased significantly during winter and late spring of each year, suggesting spawning events. The condition index was not useful in describing the annual reproductive cycle of M. mactroides . Ash-free, shell-free dry mass was chosen to detect the condition of the specimens, and this significantly correlated with monthly mean SST and the gametogenic cycle. Annual recruitment patterns during summer–autumn indicated a 3-month-long planktonic phase of M. mactroides . The reproduction cycle and gonad development of M. mactroides showed only weak differences between data from the present study and those collected 40 years ago.
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infestation of the surf clam Mesodesma donacium by the spionid polychaete polydora bioccipitalis
Journal of Sea Research, 2008Co-Authors: Olaf Heilmayer, Jose M Riascos, Jurgen Laudien, Marcelo E Oliva, Wolf ArntzAbstract:The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Nino events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.
Eduardo Uribe - One of the best experts on this subject based on the ideXlab platform.
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paralytic shellfish toxins in surf clams Mesodesma donacium during a large bloom of alexandrium catenella dinoflagellates associated to an intense shellfish mass mortality
Toxins, 2019Co-Authors: Gonzalo Alvarez, José Rengel, Patricio A Diaz, Marcos Godoy, Michael Araya, Iranzu Ganuza, Roberto Pino, Francisco Alvarez, Cristina Hernandez, Eduardo UribeAbstract:In late February 2016, a harmful algal bloom (HAB) of Alexandrium catenella was detected in southern Chiloe, leading to the banning of shellfish harvesting in an extended geographical area (~500 km). On April 24, 2016, this bloom produced a massive beaching (an accumulation on the beach surface of dead or impaired organisms which were drifted ashore) of surf clams Mesodesma donacium in Cucao Bay, Chiloe. To determine the effect of paralytic shellfish poisoning (PSP) toxins in M. donacium, samples were taken from Cucao during the third massive beaching detected on May 3, 2016. Whole tissue toxicity evidence a high interindividual variability with values which ranged from 1008 to 8763 μg STX eq 100 g-1 and with a toxin profile dominated by GTX3, GTX1, GTX2, GTX4, and neoSTX. Individuals were dissected into digestive gland (DG), foot (FT), adductor muscle (MU), and other body fractions (OBF), and histopathological and toxin analyses were carried out on the obtained fractions. Some pathological conditions were observed in gill and digestive gland of 40⁻50% of the individuals that correspond to hemocyte aggregation and haemocytic infiltration, respectively. The most toxic tissue was DG (2221 μg STX eq 100 g-1), followed by OBF (710 μg STX eq 100 g-1), FT (297 μg STX eq 100 g-1), and MU (314 μg STX eq 100 g-1). The observed surf clam mortality seems to have been mainly due to the desiccation caused by the incapability of the clams to burrow. Considering the available information of the monitoring program and taking into account that this episode was the first detected along the open coast of the Pacific Ocean in southern Chiloe, it is very likely that the M. donacium population from Cucao Bay has not had a recurrent exposition to A. catenella and, consequently, that it has not been subjected to high selective pressure for PSP resistance. However, more research is needed to determine the effects of PSP toxins on behavioral and physiological responses, nerve sensitivity, and genetic/molecular basis for the resistance or sensitivity of M. donacium.
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Paralytic Shellfish Toxins in Surf Clams Mesodesma donacium during a Large Bloom of Alexandrium catenella Dinoflagellates Associated to an Intense Shellfish Mass Mortality
MDPI AG, 2019Co-Authors: Gonzalo Alvarez, José Rengel, Patricio A Diaz, Marcos Godoy, Michael Araya, Iranzu Ganuza, Roberto Pino, Francisco Alvarez, Cristina Hernandez, Eduardo UribeAbstract:In late February 2016, a harmful algal bloom (HAB) of Alexandrium catenella was detected in southern Chiloé, leading to the banning of shellfish harvesting in an extended geographical area (~500 km). On April 24, 2016, this bloom produced a massive beaching (an accumulation on the beach surface of dead or impaired organisms which were drifted ashore) of surf clams Mesodesma donacium in Cucao Bay, Chiloé. To determine the effect of paralytic shellfish poisoning (PSP) toxins in M. donacium, samples were taken from Cucao during the third massive beaching detected on May 3, 2016. Whole tissue toxicity evidence a high interindividual variability with values which ranged from 1008 to 8763 μg STX eq 100 g−1 and with a toxin profile dominated by GTX3, GTX1, GTX2, GTX4, and neoSTX. Individuals were dissected into digestive gland (DG), foot (FT), adductor muscle (MU), and other body fractions (OBF), and histopathological and toxin analyses were carried out on the obtained fractions. Some pathological conditions were observed in gill and digestive gland of 40–50% of the individuals that correspond to hemocyte aggregation and haemocytic infiltration, respectively. The most toxic tissue was DG (2221 μg STX eq 100 g−1), followed by OBF (710 μg STX eq 100 g−1), FT (297 μg STX eq 100 g−1), and MU (314 μg STX eq 100 g−1). The observed surf clam mortality seems to have been mainly due to the desiccation caused by the incapability of the clams to burrow. Considering the available information of the monitoring program and taking into account that this episode was the first detected along the open coast of the Pacific Ocean in southern Chiloé, it is very likely that the M. donacium population from Cucao Bay has not had a recurrent exposition to A. catenella and, consequently, that it has not been subjected to high selective pressure for PSP resistance. However, more research is needed to determine the effects of PSP toxins on behavioral and physiological responses, nerve sensitivity, and genetic/molecular basis for the resistance or sensitivity of M. donacium
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Accumulation and Biotransformation of Dinophysis Toxins by the Surf Clam Mesodesma donacium.
Toxins, 2018Co-Authors: Juan Blanco, Gonzalo Alvarez, Carmen Marino, José Rengel, Rosario Díaz, Helena Martín, Eduardo UribeAbstract:Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day-1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.
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depuration and anatomical distribution of domoic acid in the surf clam Mesodesma donacium
Toxicon, 2015Co-Authors: Gonzalo Alvarez, Eduardo Uribe, Helena Martín, Jorge Regueiro, Teresa Gajardo, Lorena Jara, Juan BlancoAbstract:Abstract In northern Chile, domoic acid (DA) has been detected in several bivalve species. In Mesodesma donacium , one of the most important commercial species for local fishermen, no information is available on depuration, or on the anatomical distribution of this toxin and its potential use as a palliative measure to minimize the consequences of ASP outbreaks. Deputation of DA is very fast in M. donacium , and can be adequately described by means of a two-compartment model. The estimated rates for the first and second compartments were 1.27 d −1 and 0.24 d −1 , respectively, with a transfer rate between compartments of 0.75. Having high depuration rates protects this species from being affected by Pseudo-nitzschia blooms for an extended period of time. Taking this into account, the time in which the bivalves are unsafe for consumers is very short, and therefore the economic losses that could result by the DA outbreaks in local fisheries should be moderate. In relation to anatomical distribution, at least during the uptake phase, the toxin was evenly distributed within the soft tissues, with a total toxin burden corresponding to 27%, 32% and 41% for Digestive Gland (DG), Foot (FT) and Other Body Fractions (OBF), respectively. Since the contribution of each organ to the toxin concentration is a function of both weight contribution and toxin burden, the pattern of toxin distribution showed the following trend: “all other body fractions” (OBF) > Foot (FT) > Digestive Gland (DG). Thus, the highest concentration of DA, with a contribution close to 72%, corresponds to the edible tissues (OBF + FT), while the DG (non-edible tissue) only contributes the remaining 28%. Consequently, in view of the anatomical distribution of domoic acid in M. donacium , the elimination of the digestive gland does not substantially reduce the toxicity of the final product and therefore selective evisceration would not improve their quality for human consumption.
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first identification of azaspiracid and spirolides in Mesodesma donacium and mulinia edulis from northern chile
Toxicon, 2010Co-Authors: Gonzalo Alvarez, Eduardo Uribe, Paulo Avalos, Carmen Marino, Juan BlancoAbstract:In an attempt to evaluate the risk for human consumption associated to the accumulation of lipophilic toxins by two commercially important bivalves: macha (Mesodesma donacium) and clam (Mulinia edulis) in Coquimbo Bay (Chile), monitoring of these species was carried out from March to September 2008. The samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to detect okadaic acid, dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins and spirolides. Low levels of Azaspiracid-1 and 13-desmethyl C spirolide were found in both species. The toxins were detected at different dates throughout the monitoring period and in some cases both toxins were detected in the same sample. In all cases, the concentration of the toxins was below the limit of quantification of the technique used and therefore these detections are only indicative of a potential risk. This is the first report of the occurrence of these groups of toxins in Chile and suggests that it is necessary to monitor routinely these substances to warrant public health and shellfish exportations.
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regulatory factors and structure of a component population of the spionid polydora bioccipitalis infesting the surf clam Mesodesma donacium
Journal of Aquatic Animal Health, 2011Co-Authors: Jose M Riascos, Miguel Cuturrufo, Aldo S Pacheco, Marcelo E OlivaAbstract:Abstract Spionidae, particularly polydorids, are common polychaete parasites of edible mollusks around the world. However, our understanding of the regulatory factors and population structure of these parasites is scant. In this study involving Polydora bioccipitalis and the surf clam Mesodesma donacium we evaluated (1) the environmental correlates of the prevalence and mean intensity of the infestation, (2) the relationship between the number of egg capsules and juvenile and adult parasites and the time elapsed since infestation, and (3) the spatial patterns of juveniles and adults within the host. Environmental factors showed no significant correlations with prevalence and mean intensity, suggesting that these factors do not act directly as regulators. Rather, storm surges seemingly induced clam stranding, which in turn affected both the prevalence and intensity of the infestation. The numbers of juveniles and egg capsules in blisters were significantly related to the time since infestation, suggesting ...
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environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range
Ices Journal of Marine Science, 2011Co-Authors: Jose M Riascos, Olaf Heilmayer, Marcelo E Oliva, Jurgen LaudienAbstract:Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833.Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Nino events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.
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long term parasitic association between the boring polychaete polydora bioccipitalis and Mesodesma donacium
Diseases of Aquatic Organisms, 2009Co-Authors: Jose M Riascos, Olaf Heilmayer, Jurgen Laudien, Marcelo E Oliva, Nury Guzman, Luc OrtliebAbstract:Polydora and related genera are common pests for molluscs. Establishing differences between native species and recent invaders provides the basis for understanding the effect of parasites and has implications for resource management. P. biocipitalis has been reported as a recently introduced species to the Chilean-Peruvian coast, raising concerns about its threat to native bivalve species. In contrast, studies on the infestation of P. bioccipitalis on the surf clam Mesodesma donacium, one of the most important species for shellfisheries, suggest a long-term parasitic relationship. The present study analyses infested (i.e. blistered) fossil shells of M. donacium deposited during the Holocene and Middle Pleistocene epochs and critically reviews evidence supporting the hypothesis of the recent introduction of P. bioccipitalis to the Chilean-Peruvian coast. The blistering pattern seen on fossil and recent shells can be considered species-specific for the infestation of M. donacium by P. bioccipitalis. No evidence was actually found on vectors, introduction pathways or distribution range to support the status of P. bioccipitalis as an introduced species. On the contrary, our findings point to a long-term association, at least for several hundred thousand years, between M. donacium and P. bioccipitalis.
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thriving and declining climate variability shaping life history and population persistence of Mesodesma donacium in the humboldt upwelling system
Marine Ecology Progress Series, 2009Co-Authors: Jose M Riascos, Wolf Arntz, Daniel Carstensen, Jurgen Laudien, Marcelo E Oliva, Andreas Guntner, Olaf HeilmayerAbstract:Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Nino episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Meso- desma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Nino) higher temperature and reduced salinity. Moreover, the repro- ductive spatial-temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (par- ticularly El Nino since at least the Holocene) has submitted this cold-water species to a continuous local extinction-recolonization process.
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infestation of the surf clam Mesodesma donacium by the spionid polychaete polydora bioccipitalis
Journal of Sea Research, 2008Co-Authors: Olaf Heilmayer, Jose M Riascos, Jurgen Laudien, Marcelo E Oliva, Wolf ArntzAbstract:The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Nino events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.