Abstract
Mussel larval densities may fluctuate considerably on both small spatial and short temporal scales. So far, only few and scattered data on the occurrence of mussel larvae have been reported from Danish waters. However, seasonal variation in density of blue mussel (Mytilus edulis) larvae as related to environmental factors (temperature, salinity, phytoplankton biomass) is basic information of relevance for future line-mussel farming in Danish waters. Here we report on the density of mussel larvae in a number of potential farming sites in the inner Danish waters. The mussel larval density measured in Skive Fjord, an eutrophicated inner branch of Limfjorden, during a period of 20 years, from 1989 to 2009, along with corresponding temperatures and chlorophylla, makes up the most important series of data reported here. In most years, a pronounced spring density peak and a subsequently lower autumn peak could be seen in Skive Fjord, but most conspicuous in the period 1993 to 2002 where the mean maximum spring larval density was 319 ± 260 ind·l-1. Further, data on mussel larval densities have been recorded on 4 locations in the Great Belt region: Kerteminde Bay in 2008 to 2011, and in 2008 at 3 other locations: Musholm Bay, Svendborg Sund, and Horsens Fjord. The maximum spring densities in the studied waters were observed in Skive Fjord, typically in May, whereas 10 to 100 times lower peak densities were found at the other locations studied. The reported observations show that mussel larvae are omnipresent in the studied areas and it is suggested that the larval density is sufficient forrecruitment to future line-mussel farms.
Highlights
The common blue mussel, Mytilus edulis L. may reproduce at any time of the year, but in the temperate zone spawning is most frequent during spring and summer [1]
It is well known that mussel larval densities may fluctuate considerably on both relatively small spatial and short temporal scales depending on the hydrography [11], but information on density and dispersal of mussel larvae is crucial for understanding recruitment to the adult wild stock and to aquaculture farm-ropes, only few and scattered data have up to now been reported from Danish waters
Limfjorden The mussel larval density measured in Skive Fjord during a period of 20 years, from January 1989 to January 2009, along with corresponding temperatures and phytoplankton biomass expressed as chlorophyll a are shown in Figure 2 and Figure 3
Summary
The common blue mussel, Mytilus edulis L. may reproduce at any time of the year, but in the temperate zone spawning is most frequent during spring and summer [1]. The fertilized egg develops within 24 h to a trochophora larva that soon after secrets the first larval shell to become a free swimming D-shaped veliger larva (100 to 120 μm shell length) feeding on small 2 to 4 μm particles [5]-[9]. This stage lasts between 3 and 5 weeks [10], i.e. time to reach ~300 μm, depending on environmental factors (temperature, food ration, salinity) until metamorphosis when an extensible foot appears and the larva becomes a pediveliger. It is well known that mussel larval densities may fluctuate considerably on both relatively small spatial (tens of metres) and short temporal scales (days) depending on the hydrography [11], but information on density and dispersal of mussel larvae is crucial for understanding recruitment to the adult wild stock and to aquaculture farm-ropes, only few and scattered data have up to now been reported from Danish waters
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
