192,093 research outputs found
Dispersal and remineralisation of biodeposits: Ecosystem impacts of mussel aquaculture
No full textSuspension-feeding bivalves produce biodeposits (faeces and pseudofaeces) that have much higher sinking velocities than their constituent particles. Consequently they cause sedimentation of material that might otherwise not be deposited. The benthic remineralisation of biodeposits increases sediment oxygen demand and nutrient regeneration, thus enhancing the benthic-pelagic coupling of nearshore ecosystems. In New Zealand the mussel Perna canaliculus has a high natural abundance and is also intensively cultured. This thesis examines the dispersal and remineralisation characteristics of mussel P. canaliculus biodeposits and the impacts of sedimentation from a mussel farm in the Firth of Thames on sediment biogeochemistry by combining laboratory, field and modelling studies.
Dispersal characteristics were examined in the laboratory by measuring sinking velocities and erosion thresholds of biodeposits produced by mussels of a wide size range fed three experimental diets. The results show that biodeposit dispersal is a function of mussel diet and size and thus could differ significantly between locations and seasons. Estimates of dispersal distances based on these results demonstrated that the initial dispersal of biodeposits produced by cultured mussels is not far. Depending on the hydrodynamic conditions, secondary dispersal via resuspension potentially plays a more important role in the dispersal of biodeposits from mussel farms than initial dispersal and almost certainly serves as the major means of transport of biodeposits from natural mussel beds.
Biodeposit mineralisation was studied by incubating coastal sediments with added biodeposits and measuring oxygen and nutrient fluxes as well as sediment characteristics over an 11 d period. Sediment oxygen consumption and ammonium release increased immediately after biodeposit addition and remained elevated compared to control cores without additions for the incubation period. A biodeposit decay rate (0.16 d-1) was calculated by fitting a first-order G model to the observed increase in oxygen consumption. This rate is 1 - 2 orders of magnitude higher than published decay rates of coastal sediments without organic enrichment or plant material. Nutrient fluxes during the incubation period illustrated that biodeposit remineralisation alters the stoichiometry of the nutrients released from the sediments which may potentially be more significant than the changes of the individual fluxes.
To determine the impact of a mussel farm in the Firth of Thames I measured sediment oxygen and nutrient fluxes by deploying benthic chambers, sediment characteristics by collecting sediment cores and sedimentation rates by deploying sediment traps in four seasons. Oxygen consumption and sediment nutrient release rates were generally higher under the farm compared to a reference site, demonstrating the typical response to increased organic input. Unusually low nitrogen release rates measured in summer may indicate enhanced denitrification under the farm. A simple budget demonstrated the importance of benthic nutrient regeneration in maintaining primary production in this region and that mussel culture can lead to a redistribution of nutrients. This study showed that site-specific hydrodynamic and biogeochemical conditions have to be taken into account when planning new mussel farms to prevent excessive modifications of nutrient dynamics.
Results of the laboratory and field studies conducted in this thesis were used to parameterise, calibrate and validate models of mussel biodeposit dispersal and remineralisation. A particle tracking model showed that the maximum initial dispersal of faecal pellets from the mussel farm is approximately 300 m and that pellets can be transported several times this distance via resuspension. The remineralisation model was able to simulate the increased nitrogen fluxes from the sediments well and highlighted the need for thorough calibration and parameterisation of the model.
This thesis contributed to the current understanding of the ecosystem impacts of mussel culture and provided numerical models and model parameters that will assist in the assessment of mussel culture sustainability and the contribution of mussels to the nutrient cycling in nearshore ecosystems
The biology and culture of mussels of the genus Perna
No full textThis review covers the biology and ecology of the three genera of Perna: P. viridis, P. canaliculatus and P. perna. An overview is given of the technological status of culture systems with emphasis being laid on the description of advanced culture techniques such as raft and longline systems. Postharvest handling aspects for preservation of live and processed mussels are presented in detail and public health and economic aspects of the mussel culture industry are described.Mussel culture, Biology Perna
O mexilhão Perna perna no Brasil: nativo ou exótico?
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Aquicultura, Florianópolis, 2013.A mitilicultura no Brasil se baseia no cultivo do mexilhão Perna perna (Linnaeus, 1758), que é encontrado em todo o litoral brasileiro, sendo especialmente abundante do Espírito Santo a Santa Catarina. Nos últimos anos foi lançada a hipótese de que P. perna seja uma espécie exótica no litoral brasileiro. A hipótese baseia-se na análise da malacofauna de sítios arqueológicos. Todas as contestações levantadas não remetem a uma conclusão, pois precisam de estudos específicos, com metodologias claras, aliando arqueologia, ecologia e biologia molecular. O objetivo deste trabalho foi estudar a condição de nativo ou exótico do mexilhão Perna perna no Brasil, a partir de levantamento dos resultados em sítios arqueológicos, de técnicas moleculares e de datação de conchas com C14. A datação de conchas de P. perna do sítio arqueológico do Rio do Meio/Jurerê, Florianópolis/SC, indicou que as amostras têm a idade de 720±30 e 780±30 anos. O cálculo do tempo de divergência indicou que a separação das populações brasileiras e africanas ocorreu por volta de 200 mil anos. Os resultados apontam a presença da espécie no território brasileiro muito antes do descobrimento do Brasil pelos portugueses no ano de 1500, indicando que Perna perna é de fato uma espécie nativa.Abstract : The mussel farming in Brazil is based on brown mussel Perna perna (Linnaeus, 1758), which is found throughout the Brazilian coast, with especial abundance from Espírito Santo to Santa Catarina state. In recent years, it was suggested that Perna perna is an exotic species for the Brazilian coast. The hypothesis is based on the analysis of the zooarchaeology studies in archaeological sites of Brazil. All objections raised do not offer to a conclusion, because they need specific studies with clear methodology, combining archeology, ecology and molecular biology. The objective of this work was to study the condition of the brown mussel Perna perna in Brazil if native or exotic, from survey results in archaeological sites, molecular techniques and dating of shells with C14. The dating indicated that the shells were 720±30 and 780±30 years old, respectively. The calculation of divergence time indicated that the separation of the African and Brazilian mussel populations occurred around 200 thousand years ago. The results indicate the presence of the P. perna species in Brazilian territory long before the discovery of Brazil by the Portuguese in 1500, indicating that P. perna is actually a native species of Brazil
Farming of mussels and oysters
No full textThis paper reviews the works on mussel and oyster culture conducted from 1975 to 1985 by the Southeast Asian Fisheries Development Center Aquaculture Department at Tigbauan, Iloilo, Philippines. Innovative techniques developed in increasing collection of natural seeds and in improving farming techniques are presented. Results of the work on artificial seed production, bacterial depuration, uptake and elimination of heavy metals by green mussel, investigations on red tides, and microbiology of spoilage are discussed
Origin of Spanish invasion by the zebra mussel, Dreissena polymorpha (Pallas, 1771) revealed by amplified fragment length polymorphism (AFLP) fingerprinting.
No full textContains fulltext :
75622.pdf (Publisher’s version ) (Open Access)Special Issue13 p
In-stream and hyporheic water quality of the River Esk, North Yorkshire: implications for Freshwater Pearl Mussel habitats
No full textRiver systems and their catchments are important for ecological, social and economic reasons. However, the increased and changing usage of these natural environments and resources for anthropogenic benefit have led to degradation in water quality, which has led to severe declines in aquatic species populations and their suitable habitats, as well as presenting health concerns with regards to drinking water standards. As a result of this, the Water Framework Directive (2000/60/EC) has been introduced, which is an EU legislation that requires “good ecological status” of freshwaters by 2015, providing a driver for management and conservation for UK river systems. One example of declines in species populations are freshwater pearl mussels (Margaritifera margaritifera), which are under extreme threat of extinction. Combining species revival with water quality improvements provides a method for testing effectiveness of implemented measures. This study analyses water quality, hydrological characteristics and hyporheic zone chemistry of the River Esk, North Yorkshire, through a variety of spatial and temporal scales. Changing water quality through storm events showed that general water quality of the Esk is of little concern, however, higher flows bring acidification to the upper part of the network, which presents a serious threat to freshwater pearl mussel survival. The hyporheic zone displayed interesting results in that chemical concentrations were far higher, whilst dissolved oxygen levels and redox potential were lower. Nitrate values were also lower, suggesting that reducing conditions were supporting oxygen demanding chemical reactions such as denitrification, creating undesirable habitats for aquatic invertebrates. This study concludes that there is a lack of vertical connectivity between the channel and zones of interaction
Mussel-inspired polydopamine-polyethylenimine conjugated nanoparticles as efficient gene delivery vectors for mammalian cells
No full textMussel-inspired polydopamine-polyethylenimine conjugated nanoparticles as efficient gene delivery vectors for mammalian cell
A comparative study of the behavioural responses to heavy metal pollution populations of the common mussel mytilus edulis L, collected from a polluted site(Teesmouth) and a relatively unpolluted site (Lindisfame)
No full textThis study examined the ecological differences between two populations of the common blue mussel Mytilus edulis L. The project investigated the response to heavy metal pollution, administered in the form of metal salts, to individuals from populations inhabiting 'polluted' and 'relatively unpolluted' sites. First an assessment was made of morphological differences and the tissue content of copper, cadmium, lead and zinc. There were few differences in shell morphology, a slight difference in soft tissue weight, and surprisingly, a higher tissue concentration of copper and zinc at the 'unpolluted site'. Normal filtration behaviour was compared with that in the presence of solutions of salts of heavy metal, over a short time (up to 1 hour); this showed distinct differences in tolerance between the two populations in a way which was metal specific. When administered together, doses of metal salts which produced a 30% decrease in filtration rate individually, rarely showed additively; most seemed antagonistic. There was also a distinct variation in response to equivalent doses of the same metal, and investigation of filtration rate over three hours, both in clean seawater and in the presence of copper II sulphate, showed a fluctuation over time, in a manner which was altered in response to increasing concentration of metal. It was suggested that these variations in basal filtration rate were due to alternation between an aerobic phase and an anaerobic phase. Finally an assessment was made of the rates at which copper, lead, cadmium and zinc were accumulated in the tissues, over several weeks. Doses of single metal salts producing 30% decreases in filtration rate were chosen as the test concentration, though this proved to be fatal over a period of two weeks. This section was not completed for the 'polluted site' samples, as time did not permit further collection, but the experiment was repeated for mussels from the 'unpolluted site' using doses which resulted in a 10% decrease in filtration. While the two populations could not be compared for their bioaccumulation behaviour in this instance, it was shown conclusively that all four metals were uptaken. Overall, it seemed that there was evidence for development of tolerance at both collection sites, with Lindisfame mussels apparently able to detoxify and store zinc, and possibly copper. Due to the known high quantities of metals discharged from the Tees estuary, the suggestion was made that the Teesmouth mussel population have developed the ability to secrete metal from their bodies
Caracterização morfológica, extração e identificação das proteínas do pé do mexilhão Perna perna responsáveis pela formação do bisso
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciência dos Alimentos, Florianópolis, 2013.Não existem colas sintéticas impermeáveis à água e às forças de turbulência das marés como as produzidas pelos mexilhões. Estes mecanismos adesivos de fixação se fazem através de fios, denominados bissos. As primeiras observações bioquímicas relataram que os bissos são formados por proteínas adesivas, colágeno e uma enzima polifenol oxidase. Aplicações propostas para estas proteínas adesivas incluem uma nova geração de adesivos cirúrgicos e ortopédicos, revestimentos de biossensores para fixação de antígenos e anticorpos para imuno diagnósticos e anti-incrustantes. Por sua vez, não existem trabalhos com este enfoque sobre o mexilhão Perna perna, o mais abundante Mitilydae da costa brasileira e de grande importância como recurso alimentar para as famílias locais, uma vez que é extraído como adulto para consumo direto, e como semente para o cultivo em cativeiro. Assim, o objetivo deste trabalho foi descrever a morfologia microscópica do pé do mexilhão P. perna, órgão onde as proteínas adesivas do bisso são sintetizadas e armazenadas, e identificar estas prováveis proteínas adesivas usando gel de eletroforese e posterior espectrometria de massa. Na microscopia de luz foi observada a localização das células glandulares envolvidas na formação do bisso: as glândulas colágenas, enzimáticas, fenólicas e mucosas. Das proteínas extraídas do pé do mexilhão P. perna e separadas pela técnica de eletroforese 12% SDS-PAGE foram observadas quatro bandas de interesse: três bandas na faixa de aproximadamente 97 kDa e uma banda na faixa de aproximadamente 37 kDa. A identificação destas bandas protéicas em banco de dados, após espectrometria de massa MALDI-TOF, sugere a presença de proteínas similares às seguintes proteínas: proteína de filamento de matriz 1 (tmp-1) da espécie Mytilus edulis, proteína do pé do mexilhão 2 (mfp-2) da espécie M. edulis e proteína fibrinogênica relacionada com a proteína 1 da espécie Mytilus californianus. Abstract : There are no synthetic glues that can be applied to an aqueous environment and be resistant to the turbulence forces of tides such as those generated by mussels. The mussel's adhesive apparatus is a bundle of threads, called the byssus. The first biochemical observations reported those byssus are formed by a fibrous collagenous core coated with adhesive proteins and an enzyme polyphenol oxidase. Proposed applications for these adhesive proteins include a new generation of orthopedic and surgical adhesives, and coatings for biosensors for attachment of antigens and antibodies for immunoassay diagnostics and also as anticorrosive. There are no studies with this focus on the mussel Perna perna, the most abundant Mitilydae the Brazilian coast and of major importance as a food resource for the local families, since it is extracted as an adult for direct consumption, and as seed for cultivation farms. Therefore, the aim of this study was to describe the microscopic morphology of the foot of the mussel P. perna, organ where the adhesive proteins of the byssus are synthesized and stored, and to identify those probable adhesive proteins using gel electrophoresis and further mass spectrometry. In the light microscopy was observed the location of the glandular cells involved in the formation of the byssus threads: collagen, enzyme, phenol and mucous glands. The adhesive proteins extracted from the P. perna foot were run on 12% SDS-PAGE wich detected three variants with mass around 97, and one with approximately 37 kDa. MS MALDI-TOF identification and sequence comparisons and alignments of these protein bands suggest the presence of proteins similar to the following proteins: thread matrix protein 1 (tmp-1) variants a from Mytilus edulis, mussel foot protein 2 (mfp-2) from M. edulis and fibrinogen-related protein 1 from Mytilus californianus
The ecology of freshwater bivalves in the Lake Sapanca Basin, Turkey
No full textDespite the ecological importance and globally threatened status of freshwater bivalves, the freshwater mussel fauna of Turkey has hitherto received little attention. The aim of this study was to describe the ecology of freshwater mussels of the Lake Sapanca Basin (NW Turkey) to provide baseline data against which to measure future trends. Five native mussel species belonging to three genera were encountered in surveys; Anodonta cygnea, A. anatina, Unio pictorum, U. crassus and Dreissena polymorpha. In addition, an invasive species from Asia, A. woodiana, was recorded in the region for the first time. A. cygnea and U. pictorum were the most abundant species in the lake, while U. crassus was most abundant in the associated stream. Age and growth parameters were estimated for U. pictorum and U. crassus, and indicated that the latter species had a younger median age and faster growth rate than the former, possibly a function of exclusively occupying a nutrient enriched stream. The bio-ecological features of the bivalve fauna of the Lake Sapanca Basin, as well as the implications of the introduction of A. woodiana, are discussed.Peer reviewe
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