| 1. |
- Strand, Åsa, et al.
(författare)
-
Impact of an icy winter on the Pacific oyster (Crassostrea gigas Thunberg, 1793) populations in Scandinavia
- 2012
-
Ingår i: Aquatic Invasions. - : Regional Euro-Asian Biological Invasions Centre Oy (REABIC). - 1798-6540 .- 1818-5487. ; 7:3, s. 433-440
-
Tidskriftsartikel (refereegranskat)abstract
- The Pacific oyster (Crassostrea gigas) is an invasive species that has dispersed into Scandinavia during the last few decades. The objective of this study was to evaluate the effects of extreme winter conditions on the mortality of the Pacific oyster in Scandinavia. The study was done by compiling mortality data from independent surveys in Denmark, Sweden and Norway. Winter mortality of the oysters increased with latitude, which can be explained by the colder climate experienced at higher latitudes. Mortality was also found to be affected by site specific conditions such as water depth at the sampling sites of oyster populations. Despite the severe winter conditions of 2009/2010 causing high mortality, the Pacific oyster still exists in large numbers in Scandinavia. The present investigation indicates that extreme winter conditions may result in a temporary reduction of the density of the Pacific oyster, but that the species can be expected to continue its invasion of Scandinavian coastal areas.
|
|
| 2. |
- Wrange, Anna-Lisa, 1981, et al.
(författare)
-
Massive settlements of the Pacific oyster, Crassostrea gigas, in Scandinavia.
- 2009
-
Ingår i: Biological Invasions. - 1387-3547.
-
Tidskriftsartikel (refereegranskat)abstract
- The Pacific oyster (Crassostrea gigas) is an important aquaculture species world-wide. Due to its wide environmental tolerance and high growth rate, it has also become a successful invader in many areas, leading to major ecosystem changes. Low water temperatures were previously believed to restrict the establishment of Pacific oysters in Scandinavia. However, recent surveys reveal that the Pacific oyster is now established in many areas in Scandinavia. We present data on the current distribution, abundance and age-structure in Denmark, Sweden and Norway. The biomass of oysters in the Danish Wadden Sea increased from 1,056 to 6,264 tonnes between 2005 and 2007. Massive settlements were observed along the Swedish west coast in 2007, with densities >400 oysters per m−2. In Norway, populations are established on the southern coast, and specimens have been found as far north as 60°N. The potential impacts and probable causes of this recent large-scale establishment are discussed.
|
|
| 3. |
- Mortensen, S., et al.
(författare)
-
Effects of a bio-invasion of the pacific oyster, crassostrea gigas (Thunberg, 1793) in five shallow water habitats in scandinavia
- 2017
-
Ingår i: Management of Biological Invasions. - : Regional Euro-Asian Biological Invasions Centre Oy (REABIC). - 1989-8649. ; 8:4, s. 543-552
-
Tidskriftsartikel (refereegranskat)abstract
- Management of invasive species is addressed in both national and international regulations regarding the protection of marine habitats and biodiversity and in regulations of aquaculture. The geographical range of the invasive Pacific oyster, Crassostrea gigas, is expanding, both through human mediated vectors and by natural dispersal. The species is now spreading in Scandinavia. In order to optimize the management of the oyster, including targeted monitoring and mitigation activities, knowledge on the present and future distribution and impact on the ecosystem is important. The development of the population and the potential impacts on native ecosystems were analyzed, based on the present scientific knowledge on the distribution in Scandinavia, data on new settlements and existing literature. Data was first evaluated by 14 experts (including the authors) during a workshop, relating the current status of habitats where Pacific oysters are found in Scandinavia (Low energy rock, Littoral sand and mudflats, Littoral biogenic reefs, Sublittoral sand and Sublittoral biogenic reefs) to a predicted development, thereafter assessed in relation to impact on the habitats. The assessment was done as a function of climate change in a long-term IPCC climate scenario (A1B). We conclude that Littoral biogenic reefs are at risk to obtain the highest expected increase, while all other habitats are at risk of low to moderate development of the oyster populations. Accordingly, Littoral Biogenic reefs was assessed as the habitat type at risk of the largest ecosystem effects as high densities of oysters already exist in these areas, and the densities are expected to increase rapidly until reaching a threshold density. Low energy rock and Littoral sand and mud were assessed as being subjected to moderate to high ecosystem effects. Sub-littoral sand and Sub-littoral biogenic reefs were assessed as currently being at risk of moderate ecosystem effects as there are low densities of oysters in these habitats, although densities in sublittoral biogenic reefs has the potential to increase. We discuss management and mitigation strategies based on the forecasted development and effects of the Pacific oyster populations. © 2017 The Author(s). and © 2017 REABIC.
|
|
