Introduction to Provisioning Services

Food provisioning is a prominent feature of marine bivalve production, applicable worldwide since ancient times. Easy accessibility of this food source and high nutritional value make bivalves a possible driver in human evolution. In this section bivalve meat production is addressed, as well as other provisioning services including pearls and bio-active compounds. In both bivalve aquaculture and fisheries, harvest and production for meat provisioning must be balanced against carrying capacity and its implications for other services including water quality maintenance and habitat structure. Provisioning of meat through aquaculture can be improved via hatchery and breeding advances, a necessity in the changing ocean climate.publishedVersio

Introduction to Regulating Services

Bivalves are foundation species with important regulating functions in the ecosystem. This is due to their function as filter feeders, their capacity to extract particles, to regenerate as well as store nutrients and – for the epibenthic bivalves –, their capacity to form hard structures. These services can be applied in many ways as is exemplified in this section. It seems likely that more applicable functions will emerge from the studies reviewed in this section.publishedVersio

Regulating Services of Bivalve Molluscs in the Context of the Carbon Cycle and Implications for Ecosystem Valuation

The role of marine bivalves in the CO2 cycle has been commonly evaluated as the balance between respiration, shell calcium carbonate sequestration, and CO2 release during biogenic calcification; however, this individual-based approach neglects important ecosystem interactions that occur at the population level, e.g. the interaction with phytoplankton populations and benthic-pelagic coupling, which in turn can significantly alter the CO2 cycle. Therefore, an ecosystem approach that accounts for the trophic interactions of bivalves, including the role of dissolved and particulate organic and inorganic carbon cycling, is needed to provide a rigorous assessment of the role of bivalves as a potential sink of CO2. Conversely, the discussion about this potential role needs to be framed in the context of non-harvested vs. harvested populations, given that harvesting represents a net extraction of matter from the ocean. Accordingly, this chapter describes the main processes that affect CO2 cycling and discuss the role of non-harvested and harvested bivalves in the context of sequestering carbon. A budget for deep-fjord waters is presented as a case study.publishedVersio

Rapid water temperature variations at the northern shelf of the Yellow Sea

During summer, there is great spatial variability in bottom water temperature on the northern shelf of the Yellow Sea. This variability is associated with a thermal front along the shelf. Oscillatory currents from semidiurnal and fortnightly period tides transport water masses laterally, resulting in oscillations of bottom water temperature at fixed positions, sometimes with large amplitudes. Temperature variations, as demonstrated in the present work, can cause damage to bottom-cultured scallops. In particular, in the scallop sea ranching area near Zhangzidao Island, such oscillations are evident in late summer. We constructed a spatial index of aggregated temperature variability from current model results identifying how temporal variability during the summer period varies in space. This information can be useful both in selecting favorable ranching areas and designing laboratory stress experiments on aquaculture candidate species.publishedVersio

Prøvedyrking av stort kamskjell i mellomkultur - 1995-1996

The production of King scallop (Pecten maximus) in culture may involve three steps; artificial spat production in hatchery, intermediate culture for production of seed and production of cornrnercial sized scallops in seabed cultivation. The national development programrne on scallop cultivation in Norway, the «King scallop projecb, conducted culture trials at 20 locations along the western coast of Norway (59°N- 65°N) from autumn 1995 to August 1996. Survival of scallops at the locations from the auturnn to June ranged from 0% to 95%. The main mortality seemed to occure during January-February, and the mortality was clearly related to minimum temperature measured during this period. A 100% mortality has been registered at all locations where minimum temperature was below 2°C and acceptable survival (above 70%) was estimated only at locations where minimum temperature was above 4°C. Survival during winter were higher at 15 meters depth than at 8 meters depth. In view of the very low seawater temperatures experienced during the winter of 1996, analysis of historical minimum temperature data are presented and areas considered as high risk environment for scallop cultivation have been suggested. The growth of scallops at 8 meter depth during summer, from June to August, are higher than at 15 meter depth. The farmers participating in the trial are evaluated on basis of how they managed the trial set up and the reporting of hydrographical and biological data.NORSK SAMMENDRAG:Dyrking av stort kamskjell (Pecten maximus) kan deles i tre produksjonsfaser; yngelproduksjon i klekkeri, produksjon av setteskjell i mellomkultur og produksjon av matskjell i bunnkultur. I det nasjonale næringsutviklingsprogrammet "Kamskjellprosjektet", er det fra høsten 1995 til august 1996 gjennomført prøvedyrking i mellomkultur på 20 lokaliteter langs kysten av Vestlandet og i Trøndelag. Overlevelse av kamskjell fra utsett høsten 1995 til juni 1996 var fra 0% til 95%. Størst dødeligheht ar forekommet i vintermånedene januar-februar, og dødelighet viser en klar sammenheng med laveste målte temperatur i denne perioden. Det er registrert total dødelighet på kamskjell hos alle dyrkere som har målt temperaturer lavere enn 2° C, og tilfredsstillende overlevelse (> 70%) er kun registrert hos dyrkere som har målt minimum vintertemperaturer høyere enn 4° C. Overlevelse om vinteren i 15 meters dyp var gjennomgående høyere enn i 8 meters dyp. På bakgrunn av de meget lave minimumstemperaturer som man har observert vinteren 1996, er det presentert analyser av historiske data på minimumstemperaturer. Det er gjort vurderinger av områder i forhold til risiko knyttet til lave temperaturer ved dyrking av kamskjell i mellomkultur. I vekstsesongen (sommerlhøst) var vekst hos skjell i 8 meters dyp bedre enn i 15 meters dyp. Rapportering fra dyrkerne er vurdert i forhold til opplegget for prøvedyrkingen av stort kamskjell i mellomkultur

Potential methodological influences on the determination of particle retention efficiency by suspension feeders: Mytilus edulis and ciona intestinalis

The retention efficiency (RE) of suspension-feeding bivalve molluscs depends on particle size and is generally assumed to decline below a maximum retention of particles larger than 3 to 7 µm. Previous suggestions that the RE spectrum of mussels Mytilus edulis can exhibit variability, possibly as a result of physiological regulation, have been attributed to artifacts associated with the indirect method. The possibility that variable physical properties of seston particles and/or miscalculations can result in inaccurate RE measurements was examined using 3 methodologies (static, flow-through and a new approach based on the static method) and 3 particle sources (natural seston, algal cell monocultures and clay). Measurements obtained with the static method varied depending on the selected sampling interval. However, this artifact can be removed using frequent sampling and a regression analysis approach. Accurate RE measurements can be obtained with the flow-through method when feeding behaviour is flow independent. For all particle suspensions and methods, mussels from the study site in Lysefjord, Norway, had a maximum RE for particles >8–11 µm (1 to 5 September 2015). The RE for smaller particles declined gradually, with 50–60% retention of 4 µm particles and 30–40% retention of 2 µm particles. Differences in the RE size spectra of mussels and tunicates Ciona intestinalis, collected and measured at the same site, further indicated that RE was not influenced by potentially confounding methodological factors. Assumptions regarding the RE spectrum of bivalves have contributed to many conclusions on their ecosystem interactions. The reliability of clearance rate measurements obtained using the indirect method can only be assured if the effective retention of tracer particles is confirmed and not assumed.publishedVersio