Variability in annual recruitment success as a determinant of long-term and large-scale variation in annual production of intertidal Wadden Sea mussels (Mytilus edulis)

Abstract

To understand the background of the strong variation and recent decline of stocks and production of mussels (Mytilus edulis) on tidal Xats of the Wadden Sea, we analysed long-term (twice-annual for 26 years) and multi-station (15 sites) estimates of numbers, mean individual weights, biomass, and annual production on Balgzand, a 50-km 2 tidal-Xat area in the westernmost part of the Wadden Sea (The Netherlands). Somatic production was estimated from summed growth increments of soft tissues per half-year period and expressed in ash-free dry mass (AFDM). In adults, positive values in spring/summer regularly alternated with negative values in autumn/winter, when up to »25% (mean: 14%) of individual weight gains in the preceding season were lost. No weight losses were observed during the Wrst winter of the life of mussels. The 26-year mean of net somatic tissue production P amounted to 5.5 g AFDM m ¡2 a ¡1 at a mean biomass B of 3.2 g AFDM m ¡2 ; the ratio P/B varied strongly with age composition of the mussel population and ranged between 0.5 and 3.0 a ¡1 (mean: 1.7). Within the restricted areas of mussel beds, mean biomass and annual production values were two orders of magnitude higher. In the Wadden Sea, mussel beds cover a typical 1% of extensive tidal Xat areas. Numerical densities of recruits showed straight-line relationships with subsequent life-time year-class production. Once recruits had reached an age of »10 months, their numbers predicted subsequent production within narrow limits. Production per recruit averaged 0.21 g AFDM for 10-mo recruits and was not related to recruit density. Local variation in annual production varied strongly, with maximal values between mid-tide and low-tide level, where recruitment was also maximal. Production per recruit was higher at low than at high intertidal levels. Frequently failing recruitment is indicated as the main cause of declining mussel stocks in the Wadden Sea. As in other bivalve species, a declining frequency of the occurrence of cold winters appears to govern declining recruitment success and consequently declining production.

Spatial Synchrony in Intertidal Benthic Algal Biomass in Temperate Coastal and Estuarine Ecosystems

“…Low-density Salicornia stands will increase the NDVI in summer in a limited number of high shore places. In addition, shellfish beds and mussel cultivation plots may yield an increased NDVI locally; for example, mussel beds cover less than 1% of the intertidal area in site WAD (Beukema and Dekker 2007). Benthic algae consist of both microphytobenthos and macroalgae.…”

Thriving and declining: climate variability shaping life-history and population persistence of Mesodesma donacium in the Humboldt Upwelling System

“…Establishing links between the life-history traits of M. donacium and large-scale environmental settings during nonEl Niño conditions is a crucial step in assessing the responses to El Niño and subsequent recovery. Reproduction and recruitment are key processes controlling long-term variability and persistence of marine bivalve populations (Bricelj et al 1987, Lima et al 2000, Beukema & Dekker 2007. Based on both, observational and experimental data sources, this paper aims to: (1) determine the effects of higher temperature and reduced salinity, expected under El Niño conditions, on growth and mortality of M. donacium; (2) describe the latitudinal patterns of reproductive activity and assess the link with large-scale environmental variability; and (3) analyse consequences for the long-term development and persistence of this species in Chile and Peru.…”

Hatchery broodstock conditioning of the blue mussel Mytilus edulis (Linnaeus 1758). Part I. Impact of different micro-algae mixtures on broodstock performance

“…Especially during the last two decades, some periods of intense fishing followed by frequent failing of recruitment in the Wadden Sea (The Netherlands) has caused an overall decline in wild and production stocks (Herlyn and Millat 2000;Beukema and Dekker 2007). As a result of the decline in available mussel seed, the mussel industry in The Netherlands has been greatly affected (personal comment J.W.…”