Return to sender: The influence of larval behaviour on the distribution and settlement of the European oyster
            
              Ostrea edulis

AbstractWe modelled the pelagic larval phase of native European oyster (Ostrea edulis) in the Solent. The Solent is a complex and tidally energetic environment on the south coast of the UK. Until recently it was the largest self-sustaining fishery of the native oyster in Europe. We developed a new larval settlement behavioural model that is the simplest plausible model which remains consistent with all available data and evidence on larval behaviour. We used a hydrodynamic sub-model, a Lagrangian advection sub-model, and an individual agent based model. The results demonstrate how isolated oyster assemblages can re-populate larger areas of historical inhabitance. We predict the most likely patterns of redistribution from refugia or from fisheries seeding. We show that settlement swimming behaviour is as equally important as passive hydrodynamic transport for larval survival and adult distribution and that settlement swimming behaviour has a profound impact on settlement patterns. The models show that managed broodstock refugia have the potential to seed much larger oyster beds in contrast to broad-scale seeding. Such refugia have the advantage of maintaining a locally high and mature population with potential for reef features and their associated biodiversity. We show that such refugia may be best placed in the tidally dynamic and exposed areas rather than on sheltered coastal sites as they have been in the past. Our model is insensitive to parameter variation and could be an effective and practical management tool in the face of a paucity of field data on larval distribution and behaviour.

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Phylogeography in an “oyster” shell provides first insights into the genetic structure of an extinct Ostrea edulis population

Scientific Reports ◽

10.1038/s41598-021-82020-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sarah Hayer ◽

Dirk Brandis ◽

Alexander Immel ◽

Julian Susat ◽

Montserrat Torres-Oliva ◽

...

Keyword(s):

Large Scale ◽

Wadden Sea ◽

Atlantic Coast ◽

Phylogenetic Reconstruction ◽

Oyster Shell ◽

Glacial Refugia ◽

Late Nineteenth Century ◽

Ostrea Edulis ◽

Geographic Ranges ◽

The North

AbstractThe historical phylogeography of Ostrea edulis was successfully depicted in its native range for the first time using ancient DNA methods on dry shells from museum collections. This research reconstructed the historical population structure of the European flat oyster across Europe in the 1870s—including the now extinct population in the Wadden Sea. In total, four haplogroups were identified with one haplogroup having a patchy distribution from the North Sea to the Atlantic coast of France. This irregular distribution could be the result of translocations. The other three haplogroups are restricted to narrow geographic ranges, which may indicate adaptation to local environmental conditions or geographical barriers to gene flow. The phylogenetic reconstruction of the four haplogroups suggests the signatures of glacial refugia and postglacial expansion. The comparison with present-day O. edulis populations revealed a temporally stable population genetic pattern over the past 150 years despite large-scale translocations. This historical phylogeographic reconstruction was able to discover an autochthonous population in the German and Danish Wadden Sea in the late nineteenth century, where O. edulis is extinct today. The genetic distinctiveness of a now-extinct population hints at a connection between the genetic background of O. edulis in the Wadden Sea and for its absence until today.

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Perspectives on Larval Behaviour in Biophysical Modelling of Larval Dispersal in Marine, Demersal Fishes

Oceans ◽

10.3390/oceans2010001 ◽

2020 ◽

Vol 2 (1) ◽

pp. 1-25

Author(s):

Jeffrey M. Leis

Keyword(s):

Fish Larvae ◽

Behavioural Change ◽

Larval Fishes ◽

Larval Behaviour ◽

Key Issues ◽

Modelling Effort ◽

Validation Research ◽

Vertical Positioning ◽

Study Species ◽

Demersal Fishes

Biophysical dispersal models for marine fish larvae are widely used by marine ecologists and managers of fisheries and marine protected areas to predict movement of larval fishes during their pelagic larval duration (PLD). Over the past 25 years, it has become obvious that behaviour—primarily vertical positioning, horizontal swimming and orientation—of larvae during their PLD can strongly influence dispersal outcomes. Yet, most published models do not include even one of these behaviours, and only a tiny fraction include all three. Furthermore, there is no clarity on how behaviours should be incorporated into models, nor on how to obtain the quantitative, empirical data needed to parameterize models. The PLD is a period of morphological, physiological and behavioural change, which presents challenges for modelling. The present paper aims to encourage the inclusion of larval behaviour in biophysical dispersal models for larvae of marine demersal fishes by providing practical suggestions, advice and insights about obtaining and incorporating behaviour of larval fishes into such models based on experience. Key issues are features of different behavioural metrics, incorporation of ontogenetic, temporal, spatial and among-individual variation, and model validation. Research on behaviour of larvae of study species should be part of any modelling effort.

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MICROECOLOGICAL FACTORS IN OYSTER EPIZOOTICS

Canadian Journal of Zoology ◽

10.1139/z61-050 ◽

1961 ◽

Vol 39 (4) ◽

pp. 449-485 ◽

Cited By ~ 15

Author(s):

Marshall Laird

Keyword(s):

Crassostrea Virginica ◽

Relevant Literature ◽

Organic Pollution ◽

Direct Effects ◽

Ostrea Edulis ◽

New Host ◽

Lethal Temperatures ◽

Canadian Data ◽

Dead Animal ◽

Favorable Conditions

On oyster beds as elsewhere, mud–water interfaces exhibit a biological film harboring saprobic microorganisms. The abundance of these is directly proportional to the amount of decomposing organic matter present. Different communities of protozoa and bacteria characterize each of the levels of organic pollution, which may be defined biologically in terms of a modification of the "Saprobiensystem" of Kolkwitz and Marsson. While the microorganisms concerned are not conspicuous on clean substrata except where especially favorable conditions are afforded certain of them by some dead animal or plant, their general abundance is indicative of pollution. This follows overaccumulation of reducible deposits, initiated by irregular tidal flushing, freshets, and winter icing, and rendering the microenvironment anaerobic. Ostrea edulis and Crassostrea virginica survive temporary exposure to the direct effects of such conditions as well as to near-lethal temperatures, but, weakened thereby, become vulnerable to invasion by saprobes from the enriched biological film. Unless environmental conditions improve before the oysters lose ability to recover, abnormal mortalities will be hastened by the activities of these microorganisms, notably Hexamita inflata (Protozoa). Relevant literature is reviewed, and possible local remedies are discussed. Canadian data are supported by original observations from Wales and Pakistan. Among other new host and locality records, Cristispira balbianii (Spirochaetales) and cercariae of a bucephalid trematode are listed from Ostrea belcheri from Karachi.

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