The influence of food concentration and temperature on growth and morphological differentiation of blue mussel Mytilus edulis L. larvae (original) (raw)
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E3S Web of Conferences, 2021
Spat supply for mussel farming in Morocco is essentially based on seed capture and collection from natural beds. However, natural irregularity recruitment in exploited areas and encountered difficulties during spat collection operations have led to develop and improve reproduction techniques under controlled conditions in hatcheries. The present study focused on the larvae phase aiming at assessing growth rate varies between different development stages. Trocophore larva stage had a size of 63.25 μm and reached the pedivilegere stage with a size of 272.56 μm in 18 culture days. Length growth was more significant than width growth for both H-batch and T-batch. For instance, larvae grew in terms of length quickly in H-batch than T-batch (11.10± 1.30 and 9.67 ± 1.17 μm day-1), and the same pattern was observed for T-batch larvae. Inversely, the total biomass consumed was higher during T-batch larvae rearing than H-batch ones. In contrast, the effect of feeding on growth was observed mo...
Settlement Behaviour and Size of Mussel Larvae from the Family Mytilidae (
2010
This study examines the settlement behaviour of the mytilids Mytilus galloprovincialis, Brachidontes erosus, Brachidontes rostratus, and Trichomya hirsutus larvae in response to different substrata: which were byssus threads of these four mussel species, coconut thread, and Polyvinyl chloride (PVC). The number of settlers on different substrata in the laboratory was analysed separately for each species using One-way ANOVA. A significant effect of substratum was found for all species tested. Larvae of T. hirsutus and B. erosus settled preferentially on conspecific byssus threads, while B. rostratus and M. galloprovincialis showed a similar trend. Settlement data from the field was analysed using two-way ANOVA with species and substrata as the main effect. Settlement was effected by species, but not by substrata. However, the overall settlement pattern indicated a conspecific preference with the lowest number of settlers on PVC substratum. Small size of settlement larvae of B erosus comparing to settlement larvae of T hirsutus, M galloprovinciallis, and B rostratus was observed.
Journal of Shellfish Research, 2014
Examination of the larval shell (prodissoconch) of molluscs with planktotrophic development can provide valuable information on their planktonic and early benthic life. We examined temporal variability of abundance and size among 11,994 veligers of the blue mussel (Mytilus edulis) in a coastal lagoon during settling periods between 1995 and 2009. Size and date at metamorphosis during the recruitment season were determined for 1,925 postlarvae (shell length, 255-900 mm) with prodissoconch II (PII) measurements. Emphasizing the recurrence of metamorphosis delay in the field, our study reveals a net increase in mean size at metamorphosis through time, with means for PII size ranging from 255-288 mm early in summer (after peak spawning events) to 400-422 mm (PII) during late July to early September. By estimating the ''true'' settlement date using the amount of dissoconch secreted after metamorphosis, such time-series analyses appropriately recapitulated the temporal pattern of mean pediveliger (competent larvae) size in the plankton. Our results demonstrate that greater settlement success rates were related to small size at metamorphosis-in particular, less than 320 mm. Seasonal increase in mean PII size occurring during the latter part of the settling period may be explained by competent veligers remaining adrift and delayed metamorphosis as a result of the lack of favorable encounters with a suitable substrate or the absence of specific trophic signals, or cues, required for stimulating settlement, thus forcing larvae to continue planktonic growth. The difference between the smallest and largest means for PII size corresponds to 122 mm of larval shell growth, or 47.8%, potentially representing a 322% difference in larval body mass at settlement.
Aquaculture Research, 2011
In this study, the e¡ects of three commonly used chemicals, dimethyl sulphoxide (DMSO), ethylene glycol (EG), propylene glycol (PG) and their combinations with trehalose, were evaluated on the cryopreservation of Dlarvae of the blue mussel Mytilus galloprovincialis. The larvae were harvested 30 h post-fertilization at 21 1C and cryopreserved using a standard protocol in 5%, 10% or15% of DSMO, EG and PG either as single chemical solutions or in combination with 0.2 M trehalose. Among these cryoprotectants, 5% DMSO resulted in the highest post-thaw survival rate of 55.3 AE 7.8%, although it did not signi¢cantly di¡er from those with 10% and 15% EG. The addition of 0.2 M trehalose did not improve the post-thaw larval survival rates in all the combinations assessed. The cryo-e¡ects on subsequent development were evaluated using the D-larvae frozen with 5% DMSO. The results showed that cryopreservation a¡ected both larval survival and growth in this species. The relative daily mortality rate was sig-ni¢cantly higher in treated than control groups over the period from 3 h post-thaw to day 11 post-fertilization. On day 6 post-fertilization, the average larval length in the treated group was signi¢cantly smaller than that in the control. From day 11 post-fertilization, and onwards, di¡erences in these two traits were not signi¢cant between treated and control groups. On day 21 post-fertilization, about 80% of the larvae in both treated and control groups developed eyes and the normalized survival rate in the treated group was12.5%.
Larval recruitment of the blue mussel Mytilus edulis: The effect of flow and algae
Journal of Experimental Marine Biology and Ecology, 2008
The mussel Mytilus edulis settlement and distribution was studied on plastic panels with manipulated flow regime (faired, bluff, split and angled) with or without water soluble metabolites of the green alga Cladophora rupestris. The panels were exposed vertically on a device (hydrovane) that ensures their constant orientation in the current during the peak of larval settlement at 1 m depth. In order to investigate larval distribution on the panels, half of them were coated with a silicone vacuum grease that prevents larvae from de-attachment. This grease was not toxic and did not attract or repel larvae. Low densities of larvae on the un-greased plates compared to the greased ones suggested that some of larvae left the substratum. The blue mussel larvae initially settled in regions of reduced shear velocity and then redistribute to the regions of high shear velocity. The presence of the alga increased the density of blue mussel larvae and changed their distribution on the panels. Overall, our results demonstrated that larval recruitment of M. edulis is an active process affected both by boundary-layer hydrodynamics and algal waterborne compounds.
Settlement of mussels is commonly associated with macroalgae. The eVects of 19 macroalgal species on the settlement and metamorphosis of pediveliger larvae of the mussel Mytilus galloprovincialis were investigated in the laboratory. Settlement and metamorphosis inducing activities of macroalgae Chlorodesmis fastigiata and Ceramium tenerrimum collected each month during the period between January 2005 and April 2006 were also investigated. Furthermore, C. fastigiata and C. tenerrimum were subjected to various treatments to investigate the roles of bacteria and diatoms on the algal surface in the induction of larval settlement and metamorphosis of M. galloprovincialis and the characteristics of the cues in these two macroalgae. Pediveliger larvae of M. galloprovincialis settled and metamorphosed in high percentages on Cladophora sp., Chlorodesmis fastigiata, Centroceras clavulatum, and Ceramium tenerrimum, all of which were Wlamentous in morphology. Macroalgae that were cylindrical, phylloid, Xabellate, palmate and pinnate all showed low (<8%) percentages of post-larvae but four other Wlamentous macroalgae also had low mussel larval settlement, suggesting that chemical factors may also be involved. Seasonal variation had no eVect on inductive activities of C. fastigiata and C. tenerrimum. Treatment of C. fastigiata and C. tenerrimum with formalin, ethanol and heat resulted in the signiWcant decrease or loss of their inductive activities. Survival of algal cells within treated macroalgae also decreased sig-niWcantly. Treatment of the two macroalgae with antibiotics and GeO 2 reduced the numbers of bacteria and diatoms on their surface but did not aVect their inductive activities, indicating that the cue was produced by macroalgae and not by coexisting bacteria and diatoms. However, conditioned water and crude extracts of these two macroalgae did not induce larval settlement and metamorphosis. Thus, larvae of M. galloprovincialis settled and metamorphosed on spe-ciWc Wlamentous macroalgae. The chemical cues produced by C. fastigiata and C. tenerrimum were susceptible to ethanol and heat treatments and were not recovered in the conditioned water nor in the extracts. The Wnding that inactive C. tenerrimum can be produced from culturing its apical segments provides a new tool to elucidate the chemical cue(s) from macroalgae through manipulation of their culture conditions. Communicated by S. Nishida.
Spawning, development, and the duration of larval life in a deep-sea cold-seep mussel
The Biological bulletin, 2009
We describe culturing techniques and development for the cold-seep mussel "Bathymodiolus" childressi, the only deep-sea bivalve for which development has been detailed. Spawning was induced in mature mussels by injection of 2 mmol l(-1) serotonin into the anterior adductor muscle. The mean egg diameter is 69.15 +/- 2.36 microm (+/-S.D.; n = 50) and eggs are negatively buoyant. Cleavages are spiral and at 7-8 degrees C occur at a rate of one per 3-9 h through hatching, with free-swimming blastulae hatching by 40 h and shells beginning to develop by day 12. When temperature was raised to 12-14 degrees C after hatching, larvae developed to D-shell veligers by day 8 without being fed. Egg size and larval shell morphology indicate that "B." childressi has a planktotrophic larva, but we did not observe feeding in culture. Wide distribution of this species throughout the Gulf of Mexico and amphi-Atlantic distributions of closely related congeners suggest that larvae may...
Effect of temperature on survival, growth and development of Mytilus galloprovincialis larvae
Aquaculture Research, 2011
Mussel aquaculture is widely prevalent worldwide, but generally relies on natural seed collection, which does not always meet the needs of the producers. Thus, development of mussel hatcheries is of economic interest in some parts of the world, such as Europe; it provides opportunities not only on annual reliability of seed but also on genetic improvements. To broaden knowledge on mussel larval physiology, we carried out temperature treatments (17, 20 and 24 1C) on Mytilus galloprovincialis larvae under laboratory conditions. The trials ended when 30% of the larval population was in the post-larval stage. The temperature coe⁄cient Q 10 indicated a strong relationship between temperature and increase in growth from 17 to 20 1C, but not between 20 and 24 1C. Exposure of M. galloprovincialis larvae to 17 1C resulted in poor growth, low survival and a delayed development and was considered to be inadequate for M. galloprovincialis larval culture. Rearing the larvae at 20 or 24 1C produced better growth, higher survival rates and faster metamorphosis as compared with 17 1C. The temperature region within 20 and 24 1C was suggested as adequate for the mussel M. galloprovincialis larval culture, and implications of these results on the development of commercial hatcheries were discussed.
Journal of Experimental Marine Biology and Ecology, 2007
The brackish water mussel, Mytilopsis leucophaeata, is a rapidly expanding invasive bivalve in Europe with great biofouling capacities. Being a typical brackish water species with very broad habitat preferences and environmental limits, adults are extremely tolerant to fluctuations in temperature and salinity. The life cycle of mussels however, consists of two phases: (1) from fertilization until larval settlement they are pelagic, only protected by a larval soft shell and (2) after settlement, the individuals become benthic and develop a hard mytiliform shell. The fact that adult mussels can close their protective valves is the major reason why they are important fouling species and are difficult to remove once settled. Therefore, vulnerability of different larval life stages of M. leucophaeata to temperature and salinity was investigated during standardized acute 48 h experimental tests. In addition, the survival limits of the most vulnerable larval life stage were determined at different temperature-salinity combinations. Results indicated that larval stages show a differential vulnerability: 4 h old embryos were more vulnerable to changes in temperature and salinity than 2 day old larvae. Maximal survival of 4 h old embryos was found at 22°C at salinity 15. Surrounding this optimum, conditions stayed good for survival in a rather wide range: only salinities of 0 and 25 and temperatures below 10°C or above 30°C caused high embryonic mortality. Thus, even the most vulnerable larval stage in the life cycle of M. leucophaeata can be considered highly resistant to environmental conditions. Considering the broad environmental limits of adult as well as larval M. leucophaeata, we can expect this species to appear many brackish water bodies worldwide, with only colder regions potentially limiting its invasion success.