Mussel colonization is assumed to result from factors affecting recruitment and post-recruitment survival. Despite evidence of passive migration and habitat engineering by adult mussels, the contribution to population dynamics of these processes remains unknown. This research attempts to elucidate the relative importance and scale of (1) adult movement vs. recruitment and (2) of local habitat engineering vs. habitat heterogeneity, for colonization by the blue mussel, Mytilus spp., in the St. Lawrence Estuary, Quebec. Transplants of marked mussels were used to test these ideas. Our results support the hypothesis that colonization mostly occurs through disturbance-mediated adult movement. The scale of this displacement was quantified. Colonization was accelerated by topographic heterogeneity and engineered habitat propagation. These results counter the notion that mussel population dynamics are solely regulated by recruitment and growth, and suggest that distribution patterns are also upheld by adult aggregation and movement from the local scale to landscape level.

Recently, the assumption that marine populations are demographically open due to long-distance larval dispersal has increasingly been challenged. Here we present a large-scale, multi-year survey of blue mussel ( Mytilus spp.) abundance and recruitment along the Southern shore of the St. Lawrence Estuary, Quebec. Using spatial statistical tools we detected significant positive cross-covariance between upstream adults and downstream recruitment at a 14-35 km scale. Adult abundances in subsequent surveys proved to be best explained by past patterns of recruitment, rather than growth indices, or the local supply of recruits. Fucus spp., large macroalgae with much shorter planktonic periods, displayed no evidence of dynamic coupling. Recruitment was instead correlated with growth rate, indicating that local conditions may drive rates of reproduction by Fucus spp. plants. These results provide the first direct quantification of spatio-temporal demographic coupling between adult production and recruitment using survey data, with consequences for metapopulation and marine reserve design.

Thesis (Ph.D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.

Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Restricted until June 1999. Bibliography: leaves 84-95.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 63-71. Also available online.

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Eutrophication of seas, particularly near the coasts, is a topic of high current concern. Itleads to increased primary production and a higher frequency of algal blooms. The enhancedprimary production also increases the turbidity of the water, making it harder for ecologicallyimportant benthic macro algae, e.g. seaweed, to colonize bottoms on deeper waters. EU directives, as well as national law, demand decreases in nutrients, e.g. nitrogen, reachingthe sea. Another approach to decreasing the amount of nutrients in the sea could be musselfarming. Mussel farming is an established, albeit small, industry on the Swedish west coast. The useof mussels to remove nitrogen, however, is a more recent application. Lysekil municipalityhas been granted exemption from improving the nitrogen removal in Långevik waste watertreatment plant. Instead, mussel farms are used to remove nitrogen, which was estimated to bea less costly solution. This thesis investigates the advantages in money and energy in using mussel farming. Theuse of a mussel farm to remove nitrogen from sea water is compared with removing nitrogenin a WWTP. In addition, the production of mussel fertilizer, through a composting process, iscompared with producing a corresponding amount of artificial fertilizers. The results show that mussel farms are neither more economic nor energy efficient inremoving nitrogen and producing fertilizer than the conventional alternatives examined Mussel fertilizer, however, is not the most lucrative product that the mussels from the farmcan give. Alternatives, such as fodder or human consumption, are discussed in the report. Furthermore, the mussel fertilizer qualifies as organic fertilizer. A comparison with otherorganic fertilizers could prove mussels more economic or energy efficient, but such acomparison is out of the scope for this thesis. Finally, some data, e.g. the energy demand for nitrogen removal in the WWTP, were roughestimations. More research and investigations are needed in order to achieve more accurateconclusions. / Eutrofiering i haven, speciellt kustnära vatten, är ett högaktuellt problem. Det leder till ökadprimärproduktion och frekvens av algblomningar. Den förhöjda primärproduktionen lederäven till ökad turbiditet, något som försvårar för ekologiskt viktiga bentiska arter, t.ex. sjögräs(ålgräs), att kolonisera bottnar på djupare vatten. Så väl EU-direktiv som nationell lagstiftning kräver en minskning i näringsämnen, bl.a.kväve, som når havet. Ett verktyg för att klara av dessa minskningar kan vara musselodlingar. Musselodling är en etablerad, men liten, industri på den svenska västkusten. Musslor som enkväveavskiljningsmetod är däremot en ny tillämpning. Lysekil kommun har fått undantag frånatt bygga ut kvävereningen i Långevik vattenreningsverk. I stället används musselodlingar föratt ta bort kväve, vilket ansågs vara en billigare metod. Detta examensarbete undersöker fördelarna i pengar och energi i att användamusselodlingar för att få bort kväve från havsvatten, jämfört med att avskilja kväve ivattenreningsverk. Dessutom jämförs produktionen av musselgödning, genom att komposteramusslor från musselodlingen, med att producera motsvarande mängder med konstgödsel. Resultaten visar att musselodlingar vare sig är billigare eller mer energieffektiva än dekonventionella alternativen för att ta bort kväve och producera gödsel. Musselgödning är däremot inte den mest lönsamma produkt som musslorna frånmusselodlingen kan ge. Alternativ som foder och mänsklig konsumption diskuteras i rapporten. Vidare kan musselgödning godkännas som KRAV-gödsel. I en jämförelse mot andraKRAV-gödsel kan musselgödning visa sig mer ekonomisk eller energieffektiv, men en sådan jämförelse ligger utanför detta arbetes tidsram. Slutligen var vissa data grova uppskattningar, t.ex. energiåtgången för kväveavskiljning i vattenreningsverk. Mer forskning och undersökningar behövs för att nå mer tillförlitligaslutsatser. / www.ima.kth.se