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Christopher D Mcquaid - One of the best experts on this subject based on the ideXlab platform.
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between a rock and a hard place combined effect of trampling and phototrophic shell degrading endoliths in marine intertidal mussels
Marine Biodiversity, 2019Co-Authors: Katy R. Nicastro, Christopher D Mcquaid, Gerardo I. ZardiAbstract:Ecosystems often face a complex combination of natural and anthropogenic disturbances. The assessment of anthropogenic pressures and co-occurring natural stressors is crucial to our understanding of ecosystem structures, dynamics and their conservation. The present study provides the first experimental assessment of the combined effects of trampling (anthropogenic stressor) and endolithic induced erosion (natural stressor) on two coexisting intertidal mussel species, Mytilus galloprovincialis (de Lamarck, 1819) and Perna Perna (Linnaeus, 1758). Mixed beds of the two species experiencing a wide range of endolithic parasitation were exposed to increasing intensities of human trampling. Our results clearly show that endolith-infested mussels are more vulnerable to trampling than non-infested individuals. At high trampling intensities, P. Perna suffered significantly lower mortalities rates than M. galloprovincialis. More than 20% of large, infested M. galloprovincialis individuals were crushed even at low trampling intensities. Unexpectedly, mortalities rates decreased with mussel size, suggesting a sheltering role of larger conspecifics. Beyond ecological interest, such findings can provide critical experimental support for conservation and management actions.
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coastal upwelling affects filter feeder stable isotope composition across three continents
Marine Environmental Research, 2019Co-Authors: Christopher D Mcquaid, Eleonora Puccinelli, Sergey Dobretsov, Ronaldo Adriano ChristofolettiAbstract:Abstract Large-scale nutrient fertilisation by coastal upwelling promotes benthic productivity through energy subsidies from enhanced phytoplankton production, and predictions of alterations to upwelling under climate change have implications for benthic ecosystem functioning. We investigated the stable isotope compositions of two bioengineers of global significance, the mussels Perna Perna and Mytilus galloprovincialis, from upwelling and non-upwelling sites in five upwelling systems. Samples from Brazil, South Africa and Oman exhibited lower δ13C values at upwelling sites than at non-upwelling sites, with clearer effects where upwelling is more intense and frequent. North West Africa showed variability, probably linked to Saharan dust input. We highlight the importance of upwelling to sustaining benthic primary consumers and the sensitivity of consumer diet to the intensity and frequency of upwelling within each region. These results have implications in relation to climate change scenario effects on upwelling events, with potential cascading effects on higher trophic levels and ecosystem functioning.
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is habitat amount important for biodiversity in rocky shore systems a study of south african mussel assemblages
Marine Biology, 2014Co-Authors: Jennifer Jungerstam, Christopher D Mcquaid, Francesca Porri, Johan Erlandsson, Mats Westerbom, Patrik KraufvelinAbstract:Habitat-forming species on rocky shores are often subject to high levels of exploitation, but the effects of subsequent habitat loss and fragmentation on associated species and the ecosystem as a whole are poorly under - stood. In this study, the effects of habitat amount on the fauna associated with mussel beds were investigated, test- ing for the existence of threshold effects at small landscape scales. Specifically, the relationships between mussel or algal habitat amount and: associated biodiversity, associ- ated macrofaunal abundance and density of mussel recruits were studied at three sites (Kidd's Beach, Kayser's Beach and Kini Bay) on the southern and south-eastern coasts of South africa. Samples, including mussel-associated macro- fauna, of 10 × 10 cm were taken from areas with 100 % mussel cover (Perna Perna or a combination of P. Perna and Mytilus galloprovincialis) at each site. The amount of habitat provided by mussels and algae surrounding the
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differential reproductive investment attachment strength and mortality of invasive and indigenous mussels across heterogeneous environments
Biological Invasions, 2010Co-Authors: Katy R. Nicastro, Gerardo I. Zardi, Christopher D McquaidAbstract:Environmental heterogeneity challenges both indigenous species and invaders and can play a defining role in the dynamics of their interactions. We compare bay and open coast habitats to show how environmental heterogeneity and seasonality affect survival and physiological performances of invasive (Mytilus galloprovincialis) and indigenous (Perna Perna) intertidal mussels. P. Perna had significantly higher attachment strength than M. galloprovincialis. Attachment was strongly correlated with hydrodynamic stress and was lower for both species in bays. Both species had a major spawning event when wave action was weakest. In bays, there was no correlation between gonad index (GI) and attachment strength for either species, but on the open coast GI was negatively correlated with attachment. In bays, maximum GI of M. galloprovincialis was 64% higher than for P. Perna, while on the open coast values did not differ between the two. Thus, on the open coast, both species invest more energy in attachment but P. Perna can accommodate energetic demands of increased byssal production without altering gonad production, while M. galloprovincialis cannot. Mortality was significantly correlated to sand stress, while the correlation with wave action was very weak in bays and non-significant on the open coast probably because sand stress peaked during periods of low wave action. The success of the invader and thus the outcomes of its interaction with the indigenous species are governed by habitat-to-habitat variability. In this case the invasive species is likely to prove a weaker competitor on the more stressful and energetically demanding open coast.
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fine scale spatial and temporal variation in settlement of the intertidal mussel Perna Perna indicates differential hydrodynamic delivery of larvae to the shore
Journal of Experimental Marine Biology and Ecology, 2008Co-Authors: Francesca Porri, Christopher D Mcquaid, S M Lawrie, S J AntrobusAbstract:Abstract Scales of spatial and temporal variation in the settlement of early and late plantigrades of the mussel Perna Perna to artificial substrata were measured on the south coast of South Africa. One study examined daily settlement over one month at three sites of similar tidal height and aspect. The sites were separated by 100′s of m with 5 replicated artificial settlement substrata approximately 1 m apart within each site. Early (
Gerardo I. Zardi - One of the best experts on this subject based on the ideXlab platform.
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between a rock and a hard place combined effect of trampling and phototrophic shell degrading endoliths in marine intertidal mussels
Marine Biodiversity, 2019Co-Authors: Katy R. Nicastro, Christopher D Mcquaid, Gerardo I. ZardiAbstract:Ecosystems often face a complex combination of natural and anthropogenic disturbances. The assessment of anthropogenic pressures and co-occurring natural stressors is crucial to our understanding of ecosystem structures, dynamics and their conservation. The present study provides the first experimental assessment of the combined effects of trampling (anthropogenic stressor) and endolithic induced erosion (natural stressor) on two coexisting intertidal mussel species, Mytilus galloprovincialis (de Lamarck, 1819) and Perna Perna (Linnaeus, 1758). Mixed beds of the two species experiencing a wide range of endolithic parasitation were exposed to increasing intensities of human trampling. Our results clearly show that endolith-infested mussels are more vulnerable to trampling than non-infested individuals. At high trampling intensities, P. Perna suffered significantly lower mortalities rates than M. galloprovincialis. More than 20% of large, infested M. galloprovincialis individuals were crushed even at low trampling intensities. Unexpectedly, mortalities rates decreased with mussel size, suggesting a sheltering role of larger conspecifics. Beyond ecological interest, such findings can provide critical experimental support for conservation and management actions.
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differential reproductive investment attachment strength and mortality of invasive and indigenous mussels across heterogeneous environments
Biological Invasions, 2010Co-Authors: Katy R. Nicastro, Gerardo I. Zardi, Christopher D McquaidAbstract:Environmental heterogeneity challenges both indigenous species and invaders and can play a defining role in the dynamics of their interactions. We compare bay and open coast habitats to show how environmental heterogeneity and seasonality affect survival and physiological performances of invasive (Mytilus galloprovincialis) and indigenous (Perna Perna) intertidal mussels. P. Perna had significantly higher attachment strength than M. galloprovincialis. Attachment was strongly correlated with hydrodynamic stress and was lower for both species in bays. Both species had a major spawning event when wave action was weakest. In bays, there was no correlation between gonad index (GI) and attachment strength for either species, but on the open coast GI was negatively correlated with attachment. In bays, maximum GI of M. galloprovincialis was 64% higher than for P. Perna, while on the open coast values did not differ between the two. Thus, on the open coast, both species invest more energy in attachment but P. Perna can accommodate energetic demands of increased byssal production without altering gonad production, while M. galloprovincialis cannot. Mortality was significantly correlated to sand stress, while the correlation with wave action was very weak in bays and non-significant on the open coast probably because sand stress peaked during periods of low wave action. The success of the invader and thus the outcomes of its interaction with the indigenous species are governed by habitat-to-habitat variability. In this case the invasive species is likely to prove a weaker competitor on the more stressful and energetically demanding open coast.
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Sand and wave induced mortality in invasive (Mytilus galloprovincialis) and indigenous (Perna Perna) mussels
Marine Biology, 2007Co-Authors: Gerardo I. Zardi, Christopher D Mcquaid, Katy R. Nicastro, Johan ErlandssonAbstract:The ability of an invasive species to spread in a new locality depends on its interaction with the indigenous community and on variation in time and space in the environment. The Mediterranean mussel Mytilus galloprovincialis invaded the South African coast 30 years ago and it now competes and coexists with the indigenous mussel Perna Perna. The two species show different tolerances to wave and sand stress, two of the main environmental factors affecting this intertidal community. P. Perna is more resistant to hydrodynamic stress than M. galloprovincialis, while the invasive species is less vulnerable to sand action. Our results show that mortality rates of the two species over a period of 6 months had different timing. The indigenous species had higher mortality than M. galloprovincialis during periods of high sand accumulation in mussel beds, while the pattern reversed during winter, when wave action was high. A negative correlation between sand accumulation and attachment strength of the two mussels showed that sand not only affects mussel mortality through scouring and burial, but also weakens their attachment strength, subjecting them to a higher risk of dislodgement. Here we underline the importance of variations in time and space of environmental stress in regulating the interaction between invasive and indigenous species, and how these variations can create new competitive balances.
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unexpected genetic structure of mussel populations in south africa indigenous Perna Perna and invasive mytilus galloprovincialis
Marine Ecology Progress Series, 2007Co-Authors: Gerardo I. Zardi, Christopher D Mcquaid, Peter R Teske, Nigel P BarkerAbstract:Genetic structure of sedentary marine organisms with planktonic larvae can be in- fluenced by oceanographic transport, larval behaviour and local selection. We analysed the pop- ulation genetic structure (based on mtDNA) of the invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna Perna along the southern African coastline. Low genetic divergence of M. galloprovincialis confirms its recent arrival in South Africa. In contrast, the genetic structure of P. Perna revealed strong divergence on the south-east coast, forming a western and an eastern lin- eage. The distribution of the 2 lineages is extraordinary. They overlap for ca. 200 km on the south- east coast, and the western lineage includes animals occurring on either side of a 1000 km break in distribution across the Benguela upwelling system. In cluster analyses, animals on the south coast grouped with others 1000s of km to the west, rather than with those only 200 km to the east. This genetic disjunction may be caused by the south-flowing Agulhas Current preventing larval dispersal, or by different selective forces acting on local populations. M. galloprovincialis spread eastward along the south coast for 15 yr, but its range extension has virtually ceased in the region of genetic disjunction in P. Perna, again indicating an oceanographic barrier to larval dispersal or selection dri- ven by sharp gradients in environmental conditions. The results suggest that local selection can pro- duce genetic structure opposite to that predicted by oceanographic data and that determining the population structure of indigenous species with similar larval dispersal can help us understand domain expansion of invading species.
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balancing survival and reproduction seasonality of wave action attachment strength and reproductive output in indigenous Perna Perna and invasive mytilus galloprovincialis mussels
Marine Ecology Progress Series, 2007Co-Authors: Gerardo I. Zardi, Christopher D Mcquaid, Katy R. NicastroAbstract:The indigenous mussel Perna Perna and the invasive mussel Mytilus galloprovincialis coexist on the low shore of the South African south coast, with partial habitat partitioning. P. Perna dominates the lower mussel zone, where hydrodynamic stress is higher than in the high mussel zone, where M. galloprovincialis dominates. Attachment strength and gonad maturation are highly demanding processes in terms of energy, the former allowing mussels to withstand wave forces, while the latter contributes to recruitment rates. During an 18 mo study, both biological parameters fluctuated seasonally. The invasive and the indigenous species spawned in different periods; gamete maturation was positively correlated with sea surface temperature only for P. Perna. For both species, attachment strength was negatively correlated with sea surface temperature, but increased in response to wave action through the production of more and thicker threads. Peaks in attachment strength coincided with periods of relatively low gamete production for both species, suggesting that mussels cannot afford to invest simultaneously in both processes. P. Perna attachment strength was always significantly higher than that of M. galloprovincialis , while the latter had a greater reproductive output. We suggest that, although high gamete production improves the ability of M. galloprovincialis to colonise free space, it may energetically limit its capacity to invade wave exposed shores.
Juliana Zomer Sandrini - One of the best experts on this subject based on the ideXlab platform.
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antifouling biocide dichlofluanid modulates the antioxidant defense system of the brown mussel Perna Perna
Marine Pollution Bulletin, 2020Co-Authors: Regina Coimbra Rola, Amanda Da Silveira Guerreiro, Heloisa Gabe, Marcio Alberto Geihs, Carlos Eduardo Da Rosa, Juliana Zomer SandriniAbstract:Abstract Dichlofluanid is a fungicide employed as a booster biocide in antifouling paints, but information its toxicity to aquatic organisms is scarce. This study aims to evaluate biomarker responses in the mussel Perna Perna exposed to dichlofluanid. Mussels were exposed to 0 (control), 0.1 μg/L (environmental concentration), 10, and 100 μg/L of dichlofluanid for 24 and 96 h. Byssus formation, oxygen consumption, and oxidative stress response were evaluated in gills and digestive glands. The results demonstrated that even the lowest dichlofluanid concentration causes a reduction in byssus biomass and water content. The higher concentrations caused an acute increase in oxygen consumption, which only returned to control levels after 96 h of exposure. ACAP levels and antioxidant enzyme activities were affected in both tissues with a larger effect observed in gill tissues as demonstrated by the IBR index. The overall results demonstrated that environmentally relevant concentrations of dichlofluanid would be deleterious to aquatic organisms.
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First evidence of transcriptional modulation by chlorothalonil in mussels Perna Perna
Chemosphere, 2020Co-Authors: Amanda Da Silveira Guerreiro, Igor Dias Medeiros, Jhonatas Sirino Monteiro, Juliana Zomer SandriniAbstract:Abstract Gills are considered a key player in organism defenses against environmental pollutants. Since it is the major site of uptake of waterborne chemicals, the modulation of important cellular defenses is expected in this tissue. Chlorothalonil, a fungicide presented in herbicides and antifouling paints, might be responsible for toxicity in marine biota. In this context, mussels were exposed to 0.1 μgL−1 and 10 μgL−1 of chlorothalonil for 24 h and 96 h. Genes from biotransformation and antioxidant defense pathways were investigated. Overall, we report, for the first time, an increase in the transcripts of the AhR-like, SULT1A1-like, CYP1A2-like, GSTO-like, MGST-like and SOD-like genes in the gills of the brown mussel Perna Perna. This up-regulation was observed mostly after 96 h of exposure to chlorothalonil. Those results reinforce the important role of gills in xenobiotic metabolism and suggest the involvement of the mentioned genes in the detoxification of the compound. Throughout biotransformation and antioxidant defenses pathway, mussels exposed to chlorothalonil are activating mechanisms of defense against this contaminant.
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antifouling biocides impairment of bivalve immune system by chlorothalonil
Aquatic Toxicology, 2017Co-Authors: Amanda Da Silveira Guerreiro, Regina Coimbra Rola, Monique Tomazele Rovani, Simone Rutz Da Costa, Juliana Zomer SandriniAbstract:Abstract Marine ecosystems are subjected to a variety of contaminants. Antifouling paints, for example, have been extensively used to protect ship surfaces from marine biofouling, but their toxicity has generated great concern. Thus, we evaluated the effect of the biocide chlorothalonil on the immune system of Perna Perna mussels. The mussels were exposed to 0 (control), 0.1 μg/L and 10 μg/L of chlorothalonil for up to 96 h. After 24 h and 96 h of exposure, the following immune-related parameters were analyzed in the hemolymph of mussels: total hemocyte count, cell adhesion, phagocytic activity, level of reactive oxygen species, cell viability and comet assay. After 24 h and 96 h of chlorothalonil exposure, cellular adhesion increased and the hemocyte viability reduced. Moreover, an increase in phagocytic activity was also observed after 96 h of exposure to cholorothalonil. The exposure to 10 μg/L of chlorothalonil for 96 h reduced the air survival capacity of mussels. Total hemocyte count, ROS generation and DNA damage were not affected by the contaminant exposure. Our results indicate that chlorothalonil affected important immune responses of the bivalves, demonstrating that this biocide has effects on non-target species. This modulation of immune system reduced the health status of mussels, which could compromise their ability to survive in the environment.
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hypoosmotic stress in the mussel Perna Perna linnaeus 1758 is ecological history a determinant for organismal responses
Estuarine Coastal and Shelf Science, 2017Co-Authors: Regina Coimbra Rola, Marta Marques Souza, Juliana Zomer SandriniAbstract:Abstract Ecological history of organisms may be related to different responses and adaptations to stressors. This study aims to evaluate whether marine brown mussels ( Perna Perna Linnaeus, 1758) collected from sites with distinct histories of fluctuations in abiotic parameters, including salinity, respond differently to hypoosmotic stress. Mussels were collected at different sites (a marine site, with no history of salinity variation, and an estuarine site, with usual salinity variations) and exposed in laboratory for 14 days to hypoosmotic stress (salinities 25 and 20). It was observed that mussels collected at the marine site showed increased oxygen consumption (VO 2 ), reduced haemolymph osmolality and concentrations of Na + , Cl − , and K + ; increased levels of ninhydrin-positive substances in the haemolymph, and no changes in gill Na + /K + -ATPase activity, as expected for osmoconforming organisms. For animals collected at the estuarine site, except for VO 2 , this same pattern was only observed on day 1 of hypoosmotic stress. Unexpectedly, on days 4 and 14, VO 2 decreased, the osmolality and ionic concentration returned to near baseline values, and mussels gill Na + /K + -ATPase activity increased at day 4. This long-term response detected for estuarine mussels is similar to that observed for osmoregulating organisms, which is very unexpected for marine bivalves. Despite being novel in the relevant literature, these results suggest that in some situations mussels could adopt osmoregulating behavior, such as increasing Na + /K + -ATPase activity and thereby probably reducing water circulating inside valves. In conclusion, these results indicate that ecological history, shown here by differences in organismal origin, influence physiological parameters of mussels in response to a stressful situation.
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effects of glyphosate on cholinesterase activity of the mussel Perna Perna and the fish danio rerio and jenynsia multidentata in vitro studies
Aquatic Toxicology, 2013Co-Authors: Juliana Zomer Sandrini, Regina Coimbra Rola, Fernanda Moreira Lopes, Hermeson Francisco Buffon, Milene Marques Freitas, Camila De Martinez Gaspar Martins, Carlos Eduardo Da RosaAbstract:Although the herbicide glyphosate [N-(phosphonomethyl)glycine] is not classified as an acethylcholinesterase inhibitor, some studies have reported reduction in the acethylcolinesterase activity after in vivo exposure to both its pure form and its commercial formulations. Considering this controversy, the objective of the present study was to investigate, in vitro, the effects of glyphosate exposure on cholinesterase activity of the brown mussel Perna Perna and of two fish species: zebrafish Danio rerio and onesided livebearer Jenynsia multidentata. For this purpose, samples of different tissues (brain and muscle for fish; gills and muscle for mussel) were homogenized and pre-incubated with different glyphosate concentrations before cholinesterase activity determination. Results demonstrated that cholinesterase from different fractions of all species tested was inhibited by glyphosate. The concentrations of glyphosate that inhibits 50% of cholinesterase activity (IC50) ranged from 0.62 mM for P. Perna muscle to 8.43 mM for J. multidentata brain. According to this, cholinesterase from mussel seems to be more sensitive to glyphosate exposure than those from the fish D. rerio and J. multidentata.
Katy R. Nicastro - One of the best experts on this subject based on the ideXlab platform.
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between a rock and a hard place combined effect of trampling and phototrophic shell degrading endoliths in marine intertidal mussels
Marine Biodiversity, 2019Co-Authors: Katy R. Nicastro, Christopher D Mcquaid, Gerardo I. ZardiAbstract:Ecosystems often face a complex combination of natural and anthropogenic disturbances. The assessment of anthropogenic pressures and co-occurring natural stressors is crucial to our understanding of ecosystem structures, dynamics and their conservation. The present study provides the first experimental assessment of the combined effects of trampling (anthropogenic stressor) and endolithic induced erosion (natural stressor) on two coexisting intertidal mussel species, Mytilus galloprovincialis (de Lamarck, 1819) and Perna Perna (Linnaeus, 1758). Mixed beds of the two species experiencing a wide range of endolithic parasitation were exposed to increasing intensities of human trampling. Our results clearly show that endolith-infested mussels are more vulnerable to trampling than non-infested individuals. At high trampling intensities, P. Perna suffered significantly lower mortalities rates than M. galloprovincialis. More than 20% of large, infested M. galloprovincialis individuals were crushed even at low trampling intensities. Unexpectedly, mortalities rates decreased with mussel size, suggesting a sheltering role of larger conspecifics. Beyond ecological interest, such findings can provide critical experimental support for conservation and management actions.
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differential reproductive investment attachment strength and mortality of invasive and indigenous mussels across heterogeneous environments
Biological Invasions, 2010Co-Authors: Katy R. Nicastro, Gerardo I. Zardi, Christopher D McquaidAbstract:Environmental heterogeneity challenges both indigenous species and invaders and can play a defining role in the dynamics of their interactions. We compare bay and open coast habitats to show how environmental heterogeneity and seasonality affect survival and physiological performances of invasive (Mytilus galloprovincialis) and indigenous (Perna Perna) intertidal mussels. P. Perna had significantly higher attachment strength than M. galloprovincialis. Attachment was strongly correlated with hydrodynamic stress and was lower for both species in bays. Both species had a major spawning event when wave action was weakest. In bays, there was no correlation between gonad index (GI) and attachment strength for either species, but on the open coast GI was negatively correlated with attachment. In bays, maximum GI of M. galloprovincialis was 64% higher than for P. Perna, while on the open coast values did not differ between the two. Thus, on the open coast, both species invest more energy in attachment but P. Perna can accommodate energetic demands of increased byssal production without altering gonad production, while M. galloprovincialis cannot. Mortality was significantly correlated to sand stress, while the correlation with wave action was very weak in bays and non-significant on the open coast probably because sand stress peaked during periods of low wave action. The success of the invader and thus the outcomes of its interaction with the indigenous species are governed by habitat-to-habitat variability. In this case the invasive species is likely to prove a weaker competitor on the more stressful and energetically demanding open coast.
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Sand and wave induced mortality in invasive (Mytilus galloprovincialis) and indigenous (Perna Perna) mussels
Marine Biology, 2007Co-Authors: Gerardo I. Zardi, Christopher D Mcquaid, Katy R. Nicastro, Johan ErlandssonAbstract:The ability of an invasive species to spread in a new locality depends on its interaction with the indigenous community and on variation in time and space in the environment. The Mediterranean mussel Mytilus galloprovincialis invaded the South African coast 30 years ago and it now competes and coexists with the indigenous mussel Perna Perna. The two species show different tolerances to wave and sand stress, two of the main environmental factors affecting this intertidal community. P. Perna is more resistant to hydrodynamic stress than M. galloprovincialis, while the invasive species is less vulnerable to sand action. Our results show that mortality rates of the two species over a period of 6 months had different timing. The indigenous species had higher mortality than M. galloprovincialis during periods of high sand accumulation in mussel beds, while the pattern reversed during winter, when wave action was high. A negative correlation between sand accumulation and attachment strength of the two mussels showed that sand not only affects mussel mortality through scouring and burial, but also weakens their attachment strength, subjecting them to a higher risk of dislodgement. Here we underline the importance of variations in time and space of environmental stress in regulating the interaction between invasive and indigenous species, and how these variations can create new competitive balances.
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balancing survival and reproduction seasonality of wave action attachment strength and reproductive output in indigenous Perna Perna and invasive mytilus galloprovincialis mussels
Marine Ecology Progress Series, 2007Co-Authors: Gerardo I. Zardi, Christopher D Mcquaid, Katy R. NicastroAbstract:The indigenous mussel Perna Perna and the invasive mussel Mytilus galloprovincialis coexist on the low shore of the South African south coast, with partial habitat partitioning. P. Perna dominates the lower mussel zone, where hydrodynamic stress is higher than in the high mussel zone, where M. galloprovincialis dominates. Attachment strength and gonad maturation are highly demanding processes in terms of energy, the former allowing mussels to withstand wave forces, while the latter contributes to recruitment rates. During an 18 mo study, both biological parameters fluctuated seasonally. The invasive and the indigenous species spawned in different periods; gamete maturation was positively correlated with sea surface temperature only for P. Perna. For both species, attachment strength was negatively correlated with sea surface temperature, but increased in response to wave action through the production of more and thicker threads. Peaks in attachment strength coincided with periods of relatively low gamete production for both species, suggesting that mussels cannot afford to invest simultaneously in both processes. P. Perna attachment strength was always significantly higher than that of M. galloprovincialis , while the latter had a greater reproductive output. We suggest that, although high gamete production improves the ability of M. galloprovincialis to colonise free space, it may energetically limit its capacity to invade wave exposed shores.
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hydrodynamic stress and habitat partitioning between indigenous Perna Perna and invasive mytilus galloprovincialis mussels constraints of an evolutionary strategy
Marine Biology, 2006Co-Authors: Gerardo I. Zardi, Marc Rius, Christopher D Mcquaid, Katy R. Nicastro, Francesca PorriAbstract:The ability of a mussel to withstand wave-generated hydrodynamic stress depends mainly on its byssal attachment strength. This study investigated causes and consequences of different attachment strengths of the two dominant mussels species on the South African south coast, the invasive Mytilus galloprovincialis and the indigenous Perna Perna, which dominate the upper and the lower areas of the lower balanoid zone, respectively and co-exist in the middle area. Attachment strength of P. Perna was significantly higher than that of M. galloprovincialis. Likewise solitary mussels were more strongly attached than mussels living within mussel beds (bed mussels), and in both cases this can be explained by more and thicker byssal threads. Having a wider shell, M. galloprovincialis is also subjected to higher hydrodynamic loads than P. Perna. Attachment strength of both species increased from higher to lower shore, in response to a gradient of stronger wave action. The morphological features of the invasive species and its higher mortality rates during winter storms help to explain the exclusion of M. galloprovincialis from the low shore. The results are discussed in the context of the evolutionary strategy of the alien mussel, which directs most of its energy to fast growth and high reproductive output, apparently at the cost of reduced attachment strength. This raises the prediction that its invasive impact will be more pronounced at sites subject to strong but not extreme wave action.
Fred A Otchere - One of the best experts on this subject based on the ideXlab platform.
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organochlorines pcbs and pesticides in the bivalves anadara senilis senilis crassostrea tulipa and Perna Perna from the lagoons of ghana
Science of The Total Environment, 2005Co-Authors: Fred A OtchereAbstract:The bivalves, Anadara (Senilia) senilis (n=95), Crassostrea tulipa (n=75) and Perna Perna (n=30) from Ghana, were analyzed for their organochlorines (pesticides and PCBs) concentrations and the body burden. A comparison was done based on two different standard PCB mixtures (Aroclor 1254 and 1260) with the percentage individual congener contribution and that of the sample. From these comparisons, it appeared that the pattern of PCB residues in the samples was neither Aroclor 1254 nor 1260. On the other hand, there was seasonal qualitative difference in the pattern that is purely marine (in the dry season) versus terrestrial input (in the wet season). SigmaPCB was 0.10 microg/g dw or 2.2 microg/g lw (median values). There was no correlation between PCB concentration and lipid content reflecting the importance of indirect contamination of the bivalves. The pesticides, aldrin, dieldrin, endrin, lindane, DDTs, HCH, HCB, endosulfan, heptachlor epoxide and heptachlor, were detected. The most abundant pesticides were the SigmaDDT: 73 and SigmaHCH: 29 ng/g dw. DDT/DDE and hept./heptachlor epoxide ratios reflect their recent applications, while the ratio for aldrin/dieldrin suggests that the use of aldrin has been discontinued, at least on the coast of Ghana.
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heavy metals concentrations and burden in the bivalves anadara senilia senilis crassostrea tulipa and Perna Perna from lagoons in ghana model to describe mechanism of accumulation excretion
African Journal of Biotechnology, 2003Co-Authors: Fred A OtchereAbstract:Seasonal sampling of the bivalves: Anadara (Senilia) senilis (n = 260), Crassostrea tulipa (n = 220), from two ‘open’ lagoons (Benya and Ningo) and a ‘closed’ lagoon (Sakumo), and Perna Perna (n = 170), from rocky shores adjacent to Benya and Sakumo, were analyzed for their total Cu, Zn, Fe, Mn, Cd and Hg concentrations and total body burden (that is concentration multiply by total flesh weight). Median concentrations for cockles were: 5, 38, 710, 10, 0.22 and 0.20 µg/g dw respectively. Cd and Hg levels in dry season samples were higher than those in wet season. While Zn and Fe dry season levels were lower than wet season with no variation in Cu and Mn. Median total body burden in cockles were: 3.3, 30.5, 370, 5.2, 0.28 and 0.13 µg respectively. Geographical variations observed were mostly due to size distribution rather than the ecological differences between stations. Log-transformed regression relationships between body burden and size were used to compare the species. Relationship between condition index, body burden and concentration were used to develop a model to describe mechanism of accumulation/excretion.
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mercury in the bivalves anadara senilia senilis Perna Perna and crassostrea tulipa from ghana
Science of The Total Environment, 2003Co-Authors: Fred A Otchere, Claude R Joiris, Ludo HolsbeekAbstract:Three bivalves: Anadara (Senilia) senilis (n=220), Crassostrea tulipa (n=260) from two 'open' lagoons (Benya and Ningo) and a 'closed' lagoon (Sakumo), and Perna Perna (n=170) from rocky shores adjacent to Benya and Sakumo, were analyzed for their total and organic Hg concentrations and total body burden. Median concentrations for cockles were 0.20 μg/gdw for the wet season and 0.36 μg/gdw for the dry season. Total mercury concentration for both mussels and oysters ranged from 0.04 to 0.84 μg/gdw. Seasonal variations and age effect were detected in all the species but no significant spatial variation was found along the coast. Organic (methyl) mercury concentration ranged from 0.03 to 0.55 μg/gdw was stable without age effect. The median relative organic mercury varied between 30 and 80% depending on the season, location, species and the type of lagoon. The lower concentrations in the wet season were due to primary production and dilution effect. Log-transformed regression relationships between body burden and size were used to compare the species. © 2002 Elsevier Science B.V. All rights reserved.