| 1. |
- Willman, Sebastian
(författare)
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Testing the role of spines as predatory defense
- 2007
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Ingår i: Journal of Shellfish Research. - 0730-8000 .- 1943-6319. ; 26:1, s. 261-266
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Tidskriftsartikel (refereegranskat)abstract
- Spines are frequently considered to be an important physical defense against predators. This experiment shows that spines do not always function successfully as physical protection. Using natural predators and prey (the drilling muricid gastropod Nucella lamellosa (Gmelin 1791) and the mussel Mytilus trossulus (Gould 1850)) this experiment used artificial spines in different configurations and densities to try to assess the role of spines as predatory defense. The presence of spines did not inhibit the predator from choosing ornamented prey. Greater spine density did not improve the probability of surviving a predator encounter. Although mean handling time increased to some extent with higher spine density, the outcome of the encounter was the same. Presence or density of spines did not deter predators from attacking prey, and experimental prey with greater spine-density experienced greater mortality than did specimens with fewer spines. Drillhole dimensions differed slightly between the treatments, probably as a consequence of difficulties for the gastropod to maneuver its accessory boring organ (ABO) in between the spines.
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| 2. |
- Baden, Susanne Pihl, 1952, et al.
(författare)
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Declining populations of mytilus spp. In north atlantic coastal waters-A swedish perspective
- 2021
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000. ; 40:2, s. 269-96
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Forskningsöversikt (refereegranskat)abstract
- During the past 2–3 decades, the spatiotemporal distribution of Mytilus spp. in coastal waters of the North Atlantic has changed considerably. In general, reduced abundances of Mytilus are observed, but there is a great degree of local variation, and some areas are also experiencing recovery after declining events. In this review, hypotheses regarding the causes behind the changes are presented with focus on a Swedish perspective. Excessive exploitation of mussel banks combined with direct and indirect effects of climate change are most probably the main drivers of Mytilus spp. decline in large parts of the North Atlantic. On the Swedish west coast, the wild stocks have disappeared despite no overfishing. Paradoxically, they thrive in mussel farms and on other non-demersal substrates. Changes in predation from, for example, increased wintering populations of eiders (Somateria molissima; 10-fold) and green crabs (Carcinus maenas; 3-fold), alteration of natural substrates elicited by eutrophica- tion, and exacerbated by climate change (increased sea surface temperature, precipitation and extreme weather events) are most likely the key factors for the decline. Most anthropogenic stressors may not be decisive by themselves, but combined effects can potentially be fatal to Mytilus spp. adults and larvae.
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| 3. |
- Both, Adrianus, 1985-, et al.
(författare)
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Growth and biochemical composition of Mytilus edulis when reared on effluent from a cod, Gadus morhua, aquaculture facility
- 2012
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 31:1, s. 79-85
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Tidskriftsartikel (refereegranskat)abstract
- This study determined the growth and biochemical composition of blue mussels (Mytilus edulis) reared on effluent from Atlantic cod (Gadus morhua) and compared it with mussels reared on a standard shellfish diet. Feeding trials lasted 6 mo, and mussels were sampled on a monthly basis. Dry weight, ash-free dry weight, shell length, and condition index were all significantly higher in algae-fed mussels at the end of the experiment compared with effluent-fed mussels. The carbon content decreased for mussels fed both diets; however, their nitrogen and protein content increased, with effluent-fed mussels having significantly more nitrogen and protein than algae-fed mussels, suggesting that effluent can increase mussel growth. Total lipid and fatty acid (FA) content decreased for effluent-fed mussels at the end of the experiment. There were no significant differences in the lipid class composition between mussels fed the 2 diets. Mussels fed both diets significantly decreased in the amount of 14:0, 16:1ω7, 16:2ω4, 16:4ω1 and 20:5ω3, and effluent-fed mussels also decreased in 18:4ω3 and 21:5ω3, as well as increased in the amount of 17:1, the Zooplankton markers 20:1ω11 and 22:1ω11, and the dienoic nonmethylene-interrupted fatty acids (NMIDs) 20:2a and 22:2b. Significant differences in the amount of individual FAs between mussels fed the 2 diets included a larger amount of 18:2ω6 and 20:4ω6 in algae-fed mussels, and a significantly larger amount of 16:4ω1 in mussels fed effluent. Mussels fed both diets underwent significant increases in the proportion of bacterial FAs, ω6 FAs, Zooplankton markers, and NMIDs. Effluent-fed mussels had a significantly larger proportion of monounsaturated FAs, Zooplankton markers, and NMIDs, as well as a smaller proportion of polyunsaturated FAs, and ω3 and ω6 FAs than algae-fed mussels. The increased presence of Zooplankton markers supports the use of these FAs to track aquaculture wastes.
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| 4. |
- Collin, Betty, 1976, et al.
(författare)
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The origin of vibrio cholerae influences uptake and persistence in the blue mussel Mytilus edulis
- 2012
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 31:1, s. 87-92
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio cholerae may cause diarrheal diseases and wound infections, both of which have the potential to be fatal. Transmission to humans is often linked to consumption of contaminated shellfish/drinking water or dermal exposure to water (e.g. when swimming). In this study, we investigated whether different isolates of Vibrio cholerae differ in terms of accumulation, persistence, and viability when encountering blue mussels (Mytilus edulis). Mussel uptake and elimination of three different V. cholerae strains were compared: one fatal clinical non-O1/O139 isolate, one highly potent El Tor biotype, and one marine strain isolated from blue mussels. The results showed that the uptake of the marine strain was significantly higher than the clinical strain, but the elimination process of the marine strain was also more efficient. The El Tor strain was not at all ingested by the mussels. In addition, the survival of bacteria when incubated together with M. edulis hemocytes was tested in vitro. The viability of clinical strains was unaffected by the presence of hemocytes, and the marine strains were even more resistant and able to multiply. We conclude that the highly virulent El Tor biotype was not taken up by the mussels and could thereby escape the mussels' elimination process. The potentially fatal non-O1/O139 V. cholerae strain may accumulate in low numbers, but could be very persistent in mussels.
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| 5. |
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| 6. |
- Dupont, Samuel, 1971, et al.
(författare)
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First Evidence of Altered Sensory Quality in a Shellfish Exposed to Decreased pH Relevant to Ocean Acidification
- 2014
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 33:3, s. 857-861
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how seafood will be influenced by coming environmental changes such as ocean acidification is a research priority. One major gap in knowledge relates to the fact that many experiments are not considering relevant end points related directly to production (e.g., size, survival) and product quality (e.g., sensory quality) that can have important repercussions for consumers and the seafood market. The aim of this experiment was to compare the survival and sensory quality of the adult northern shrimp (Pandalus borealis) exposed for 3 wk to a temperature at the extreme of its thermal tolerance (11 degrees C) and 2 pH treatments: pH 8.0 (the current average pH at the sampling site) and pH 7.5 (which is out of the current natural variability and relevant to near-future ocean acidification). Results show that decreased pH increased mortality significantly, by 63%. Sensory quality was assessed through semiqualitative scoring by a panel of 30 local connoisseurs. They were asked to rate 4 shrimp (2 from each pH treatment) for 3 parameters: appearance, texture and taste. Decreased pH reduced the score significantly for appearance and taste, but not texture. As a consequence, shrimp maintained in pH 8.0 had a 3.4 times increased probability to be scored as the best shrimp on the plate, whereas shrimp from the pH 7.5 treatment had a 2.6 times more chance to be scored as the least desirable shrimp on the plate. These results help to prove the concept that ocean acidification can modulate sensory quality of the northern shrimp P. borealis. More research is now needed to evaluate impacts on other seafood species, socioeconomic consequences, and potential options.
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| 7. |
- Hernroth, Bodil, 1951-, et al.
(författare)
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Influence on uptake, distribution and elimination of Salmonella typhimurium in the blue mussel, Mytilus edulis, by the cell surface properties of the bacteria
- 2000
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Ingår i: Journal of Shellfish Research. - 0730-8000 .- 1943-6319. ; 19:1, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- This study was carried out to investigate whether the cell surface charge of Salmonella typhimurium could influence the kinetics of uptake, distribution, and elimination in the blue mussel, Mytilus edulis. The bacteria (1 mu m) were labeled with Tc-99(m) in the presence of stannous fluoride. Two different concentrations of stannous fluoride were used to produce differences in the cell surface charges of the bacteria. A set of mussels in the investigation were also given Sn-113-labeled microspheres (15 mu m) together with bacteria to compare the impact between particle size and cell surface properties on the distribution kinetics. The distribution of radiolabeled particles in the mussel was followed and analyzed with a computer-aided gamma camera that can detect two isotopes simultaneously. Finally. the mussels were dissected and the radioactivity in the fractions was measured with a well-shielded NaI(Tl) detector. The reduced cell surface charge of S. typhimurium enhanced the preingestive selection on the gills or labial palps as well as the postingestive selection in the digestive glands in such a way that it became similar to the microspheres, despite the size differences. The uptake of the bacteria labeled in the presence of less stannous fluoride was significantly lower. However, the subsequent absorption of these bacteria in the digestive gland was greater, because the recovery of radioactivity outside the digestive tract was higher than for the more manipulated bacteria and the microspheres. Likewise, the elimination of the more manipulated bacteria was similar to that of the microspheres and significantly higher than that of the less affected bacteria. It is concluded that the cell surface properties of bacteria, possibly the charge, influence the uptake, distribution, and elimination in M. edulis and that this factor could have the same influence as size on the uptake capacity.
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| 8. |
- Joyce, Alyssa, et al.
(författare)
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Experimental effects of temperature and photoperiod on synchrony of gametogenesis and sex ratio in the European oyster Ostrea edulis (Linnaeus)
- 2013
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 32:2, s. 447-458
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Tidskriftsartikel (refereegranskat)abstract
- Insufficient knowledge about physiological processes underpinning reproduction in the European flat oyster, Ostrea edulis (Linnaeus), presents a number of unique challenges when designing a large-scale selective breeding program for hatchery production. The European flat oyster is a larviparous, protandric hermaphrodite wherein asynchronous spawns and variable sex ratios can lead to loss of genetic diversity and inbreeding depression within hatchery populations as a result of disproportionate gametic contributions in mass matings. A better understanding of O. edulis physiology in relation to environmental factors has the potential to improve hatchery processes for synchronization of gametogenesis, thus increasing fertilization potential and maximizing breeding population size of broodstock. This study sought to determine whether specific conditioning procedures-notably, manipulation of temperature and photoperiod-could be used to improve synchrony of gametogenesis and predictability of sex ratios in O. edulis. Two trials of accelerated yearly variations of temperature and photoperiod were conducted to uncouple the specific role of these factors in the timing of gametogenesis and sex of gametes over several spawning cycles. Histological analysis and quantitative analysis of gonad using a gonad filling index allowed for determination of sex ratios and staging of gametogenesis. Temperature was a controlling factor, although experimental results suggested that the effects of photoperiod, uncoupled from temperature, had no effect on the timing or rate of gametogenesis, or on sex ratios during a breeding season. A better understanding of factors affecting sex ratio and synchrony in timing of gamete release will allow for improved conditioning and broodstock handling protocols in the selective breeding of O. edulis.
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| 9. |
- Joyce, Alyssa, et al.
(författare)
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Toward Selective Breeding of a Hermaphroditic Oyster Ostrea chilensis: Roles of Nutrition and Temperature in Improving Fecundity and Synchrony of Gamete Release
- 2015
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 34:3, s. 831-840
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Tidskriftsartikel (refereegranskat)abstract
- Physiological characteristics of gametogenesis, fertilization, and early larval development in Ostrea chilensis (Philippi, 1845) pose a number of challenges for selective breeding, despite strong commercial potential. In wild populations, this larviparous protandric hermaphrodite exhibits asynchronous gonadal maturation and relatively low fecundity. Reproductive success and genetic diversity in a hatchery population are primarily determined by female fecundity and fertility, as well as synchrony of female gonad development. Better hatchery control of the reproductive cycle can lead to more cost-effective and reliable breeding. This study examined factors such as feed and temperature in an attempt to increase reproductive rates and female sex ratios in brood stock. Oysters held under two different hatchery conditioning regimes-flow-through outdoor nursery ponds and temperature-controlled indoor tanks-spawned earlier and had higher reproductive rates than natural or farmed populations. Oysters were sampled over 6 months with histological analysis used to assess seasonal gamete patterns. Magnetic resonance imaging was also trialed and compared with histology findings. Significant increase in female gonad proportion and improved synchrony of egg maturation was observed through manipulation of feed and temperature. The implications of these findings for implementing a cost-effective selective breeding program in this species are outlined.
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| 10. |
- Li, L. S., et al.
(författare)
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CONFLICTING EFFECTS OF PREDATOR CUE AND OCEAN ACIDIFICATION ON THE MUSSEL MYTILUS CORUSCUS BYSSUS PRODUCTION
- 2015
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 34:2, s. 393-400
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the impact of ocean acidification and warming on communities and ecosystems is a researcher priority. This can only be achieved through a combination of experimental and field approaches that would allow developing a mechanistic understanding of impacts across level of biological organizations. Surprisingly, most published studies are still focusing on single species responses with little consideration for interspecific interactions. In this study, the impacts of a 3 days exposure to three parameters (temperature, pH, and presence/absence of the predator cue of the crab Charybdis japonica) and their interactions on an ecologically important endpoint were evaluated: the byssus production of the mussel Mytilus coruscus. Tested temperatures (25 degrees C and 30 degrees C) were within the present range of natural variability whereas pH (8.1, 7.7, and 7.4) covered present as well as near-future natural variability. As expected, the presence of the crab cue induced an antipredator response in Mytilus coruscus (significant 10% increase in byssus secretion rate, 22% increase in frequency of shed byssus, and 30% longer byssus). Decreased pH but not temperature had a significant negative impact on the same endpoints (up to a 17% decrease in byssus secretion rate, 40% decrease in frequency of shed byssus, and 10% shorter byssus at pH 7.3 as compared with pH 8.1) with no significant interactions between the three tested parameters. In this study, it has been hypothesized that pH and predator cue have different modes of action and lead to conflicting functional responses (escape response versus stronger attachment). Functional consequences for ecosystem dynamics still need to be investigated.
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