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1.
The influence of wave exposure and of tidal height on mussel (Perna perna Linnaeus) population structure (size, density, biomass and adult/juvenile correlations) was examined at 18 sites along the
south coast of South Africa. Sites were classified as exposed or sheltered prior to sampling, without reference to the biota,
on the basis of aspect, topography and wave regime. A single set of samples was collected from each site during three spring
tide cycles. Adult mussels on these shores almost always attach directly to the rocks, and layering of mussels is virtually
absent. Shore height always had a strong influence on population structure, but exposure had significant effects only lower
on the shore, and almost exclusively on mussel sizes. Principal component analysis (PCA), based on size distribution data
for each population, revealed a general upshore decrease in the modal size of the adult cohort. The effects of exposure on
size distribution, however, varied with tidal height. PCA separated exposed zones, with larger mussels, from sheltered zones
on the low-shore. Farther upshore the two shore types were increasingly confounded. The maximum size of mussels showed a similar
pattern, with significant differences (ANOVA, p < 0.05) between exposed and sheltered sites only on the low- and mid-shores. Density was calculated from randomly placed
quadrats (i.e. not necessarily from areas of 100% cover) and showed a different pattern. Adult (>15 mm) densities decreased
up the shore, with low-, mid- and high-shore zones being significantly different from one another (ANOVA, p < 0.0001; followed by multiple range tests). However, exposure had no significant effect on density, nor was there a significant
interaction with zone. Recruit (<15 mm) densities were positively correlated with adult (>15 mm) densities in all zones and
for both exposure regimes ( p < 0.05 in all cases), but there was considerable variability and extremely low predictability in these relationships (r
2 generally <0.2). Predictability tended to be greater towards the high-shore, where adults were more clumped. As with density,
biomass was not affected by exposure, but decreased upshore as mean size and density decreased. A reduction in the influence
of exposure farther upshore may be caused by greater emersion overriding the effects of exposure. The presence of free space
within mussel beds and significant correlations between recruit and adult densities suggest that these mussel populations
are recruit limited.
Received: 7 January 2000 / Accepted: 6 July 2000 相似文献
2.
Habitat-forming, ecosystem engineer species are common in most marine systems. Still, much uncertainty exists about how individual
and population-level traits of these species contribute to ecosystem processes and how engineering species jointly affect
biodiversity. In this manipulative field experiment, we examined how biodiversity in marginal blue mussel beds is affected
by blue mussel (1) body size, density and patch context and (2) presence of fucoid and algal structures. In the study area,
bladder-wrack (Fucus
vesiculosus), filamentous algae and blue mussels (Mytilus edulis) coexist at shallow depths in a variety of patch configurations and offer complex habitats with a high variability of resources.
We hypothesized that complexity in terms of mussel bed structure and algal presence determines species composition and abundance.
Results from the experiment were compared with macrofaunal communities found in natural populations of both engineering species.
Results show that the physical structure and blue mussel patch context are important determinants for species composition
and abundance. Results further show that the presence of algal structures positively affects diversity in blue mussel habitats
due to increased surface availability and complexity that these algae offer. This study shows that blue mussel beds at the
very margin of their distribution have an indisputable function for promoting and maintaining biodiversity and suggest that
facilitative effects of habitat-modifying species are important on Baltic Sea rocky shores with fundamental importance to
community structure. 相似文献
3.
The blue mussel, Mytilus edulis, is the most conspicuous animal species in the northern Baltic rocky sublittoral. In the studied area the species lives at the margin of its salinity tolerance. Although dwarfed by the low-salinity conditions, blue mussels in the northern Baltic are very abundant and have a decisive role in the benthic and pelagic ecosystems. We studied abundance, size distribution, biomass and growth rate of blue mussels along a 270 km salinity gradient in the northern Baltic Sea. Samples (n=317, 1998-1999) from moderately exposed and exposed rocky shores at seven study areas were collected in the southern Archipelago Sea in the west and into the central Gulf of Finland in the east, where the species is becoming increasingly rare. The results show a marked decline in mean mussel size and biomass from the saline west to the less saline east. The growth rate also decreased with lower ambient salinity. However, abundance of small mussels was considerably higher in the central and eastern parts of the study area. Vertically, the highest biomass was recorded at intermediate depths (5 and 8 m), being lower at both shallower (3 m) and deeper bottoms (12 m). It is concluded that salinity is the foremost factor determining size structure and growth rate among populations within the area. The results suggest that predation further influences the population structure of blue mussels living at the edge of their range in the central Gulf of Finland ultimately set by their salinity tolerance. 相似文献
4.
Suspension-feeding bivalves are organisms of major functional importance in several aquatic environments around the world. They are also important food items for many fish and benthivorous seabirds. It has commonly been thought that predation pressure on blue mussel (Mytilus edulis) populations is negligible in the Baltic Sea, owing to the scarcity of major invertebrate predators such as starfish and crabs. It has recently been shown, however, that the blue mussel is the main food item for roach (Rutilus rutilus) in the archipelago areas of the western Gulf of Finland, where this freshwater fish species has become increasingly abundant, mainly due to increased eutrophication. To quantify the influence of roach predation on blue mussel populations we measured the standing biomass and size structure of the local blue mussel population and used a bioenergetic model to estimate mussel consumption by individual roach during two consecutive summers, 1997 and 1998. The results of the model were combined with existing data on roach abundance, giving annual consumption estimates of 75–105 kg blue mussel dry weight ha–1 in the study area, approximately two-thirds of these consumed mussels being >10 mm. This corresponds to approximately one-third of the standing population of mussels >10 mm in the area. Our results suggest that the predation effects of vertebrates on Baltic blue mussel populations are not insignificant, as previously believed. Predation by roach and other predators may have an important structuring effect on unstable blue mussel communities within the Gulf of Finland, where the species lives at the edge of its range.Communicated by M. Kühl, Helsingør 相似文献
5.
Neil LeBlanc Réjean Tremblay Jeff Davidson Thomas Landry Mary McNiven 《Marine Biology》2008,153(6):1141-1152
This study examined the effects of two selection treatments (elevated water temperature and air exposure) on the genetic and
physiological characteristics of the juvenile marine mussel, Mytilus edulis (<10 mm). Genetic effects were measured on five allozymes and fitness assessed using physiological tests to estimate energy
balance (scope for growth) as well as size, growth and survival. The in vitro treatments resulted in 48% mortality from an
air exposure of 11 h at 27°C and 76% mortality from a 6-h exposure to 33°C water. Survivors (n = 1,152) of each treatment along with controls (n = 2,304) were measured and randomly placed in compartmentalized cages. Mussels were deployed to three bays in Prince Edward
Island, Canada and monitored over a 10-month period. Initially, both of the treatments had an effect on mussel size and increased
the heterozygosity of the surviving mussels. Physiological analyses after 3 months in the field showed that the two treated
mussels showed lower metabolic rate that the control group. After 10 months in the field, the treated mussels were larger
and had lower mortality than the untreated control mussels. Unexplained environmental interaction in each of the bays had
an effect on allelic frequencies and heterozygosity. Overall, the results demonstrate that simple husbandry techniques can
be used to increase the productivity of mussel seed and heterozygosity measures can be used to assess fitness. However, more
field data is needed to determine the consistency of the increased productivity and if the increased productivity justifies
the costs of a selective treatment. Furthermore, because the level of heterozygosity in juvenile mussel populations can vary
considerably, both spatially and temporally, it may be effective as a warning of future natural mass mortality when overall
heterozygosity levels are found to be low. 相似文献
6.
Recruitment and population structure of Perna perna in low shore mussel beds were investigated over 15 months at six sites along the south coast of South Africa. Initial, subjective
classification of sites as wave exposed or wave sheltered (three of each) was confirmed using the dissolution of cement blocks
to measure average water flux and dynamometers for maximum wave force. Recruitment occurred throughout the year, but recruit
(1–5 mm) densities were significantly higher from January to April 1996 on both shore types. Recruit densities were positively
correlated with adult (>15 mm) densities for both shore types (P < 0.05) but the correlations were extremely weak (r
2 < 0.06 in each case). In areas with 100% cover, adult size (mean and maximum lengths) was greater on exposed sites, but density
showed the reverse and was negatively correlated with maximum wave strength (r = −0.84). Despite differences in adult densities and sizes, biomass, which is a product of the two, showed no significant
difference between the two shore types (ANOVA P > 0.05). Thus wave exposure dramatically affects density, recruitment and mussel size, but not recruitment timing or biomass
where there is 100% cover, and mediates a three-way interaction among food supply, larval supply and intraspecific competition
for space. In contrast to shores with saturation recruitment, mussel biomass here appears to be limited by recruit supply
and constraints of food, especially on sheltered shores, while density is regulated through intraspecific competition for
space primarily on exposed shores and at small spatial scales. 相似文献
7.
D. E. Pollock 《Marine Biology》1979,52(4):347-356
The natural diet and mode of feeding of the rock lobster Jasus lalandii (H. Milne Edwards) was determined in a rock-lobster sanctuary near Cape Town, South Africa. Field observations were tested and confirmed by means of aquarium studies. Rock lobsters feed mainly upon ribbed mussels Aulacomya ater (Molina), which comprise the largest component of the sessile benthic fauna. Mussel remains were found as the major constituent in 97% of the rock-lobster stomachs examined. The density of rock lobsters averaged 8,100 per hectare (0.81 m-2), while mussel biomass averaged more than 5 kg (wet whole weight) m-2 within the same depth range (12 to 30 m). More than 80% of the mussel biomass comprised large individuals between 60 and 90 mm in length. Large rock lobsters (mainly males) were capable of feeding on all sizes of mussels, although many of these were inaccessible to predation. Smaller rock lobsters became progressively more limited in the size range of mussels which they could crack open and consume. Competition between rock lobsters for small mussels appeared to be intense, as mussels of suitable size for feeding were generally in short supply to most of the rock-lobster population. Hence, feeding and growth rates of rock lobsters are likely to be affected by the relative population densities of predator and prey. Growth rates of rock lobsters could be limited by food supplies even in areas where mussel biomass is comparatively large. 相似文献
8.
We employed a novel technique to quantify how blue mussels Mytilus edulis react to predation risk in their environment by quantifying mussel gape using a Hall sensor attached to one shell valve reacting
to a magnet attached to the other. Change in gape angle per second (CHIGA) versus gape angle plots resulted in a distribution
with a boundary, which defined the maximum CHIGA of a mussel at all gape angles. CHIGA boundary plots for all individual mussels
were similar in form. However, the CHIGA boundary increased in extent with mussel length (maximum CHIGA for mussel valve closures
for mussels 2.98 and 79.6 mm long were −1.5 and −11°s−1, respectively), showing that larger mussels opened and closed most rapidly. Mussel extract added to the seawater, a factor
believed to signal predation, caused mussels to close significantly faster than otherwise (P < 0.001). This approach for assessing how mussels react to their environment indicates that mussel response to predation
is graded and complex and may well indicate animal-based assessments of the trade-off between effective feeding and the likelihood
of predation. 相似文献
9.
This study investigates effects of wave exposure on beds of the mussel Mytilus galloprovincialis and the infaunal communities associated with them. Nine sites of varying wave exposure were sampled near Groenrivier, on the west coast of South Africa. Wave exposure was measured using a Palumbi device, and exposure ranged from 7.17×103 to 18.49×103 N m–2. Percentage mussel cover at each site was measured using 50×50 cm quadrats, and three 10×10 cm samples were removed from the mussel beds in the mid-intertidal zones of each site for examination of infauna. Percentage mussel cover, mean mussel length, mussel biomass and mussel bed depth all peaked at intermediate exposures, declining towards both the most sheltered and most exposed sites. Infaunal species diversity and richness both showed the reverse trend, peaking at the most sheltered and most exposed sites, and declining at intermediate exposures. Neither infaunal abundance, nor biomass, was significantly correlated to wave exposure, although abundance was highest at sheltered sites and biomass greatest at the most exposed site, which was dominated by limpets and large robust polychaetes.Communicated by J.P. Thorpe, Port Erin 相似文献
10.
Effect of environmental factors on byssal thread formation 总被引:1,自引:0,他引:1
W. Van Winkle Jr. 《Marine Biology》1970,7(2):143-148
The effects of various factors on byssal thread formation have been examined in the laboratory using Modiolus demissus and Mytilus edulis. With M. demissus thread formation (threads/mussel/h0 and proportion of mussels forming threads decreased with increasing size; prior exposure to air enhanced subsequent thread formation; mechanical agitation reduced thread formation. In addition, low salinity acclimated mussels adapted more rapidly to 32 ppt than high salinity acclimated mussels did to 16 ppt; threads were not formed in the absence of calcium and/or magnesium; and there was no reduction in thread formation at temperatures as high as 27° to 28°C. M. edulis died and thread formation approached zero at temperatures exceeding 26°C. 相似文献
11.
Biochemical genetic variation at a leucine aminopeptidase (LAP) locus is related to salinity variation in several marine
bivalve molluscs. This paper details an investigation of the Long Island Sound model of LAP selection (LAP genotype-dependent
mortality occurring among newly settled Mytilus edulis mussels) carried out in 1997 among three M. galloprovincialis mussel populations along the salinity gradient of Wellington Harbour, New Zealand. Significant LAP genotypic heterogeneity
was observed at the LAP locus between small (<25 mm shell length) and large (>25 mm shell length) M. galloprovincialis from Petone and Eastbourne (the two sites experiencing the greatest salinity variation), whereas genotypic heterogeneity
was not significantly different between small and large mussels from Seatoun (the site experiencing the least salinity variation).
The Lap
3 allele decreased in frequency and the Lap
4 allele increased in frequency at Petone and Eastbourne, whereas the Lap
3 and Lap
4 allele frequencies remained effectively constant at Seatoun. Both these findings are consistent with the Long Island Sound
model of selection. At all three locations, the Lap
3,3 genotype decreased in frequency from small to large mussels, whereas the Lap
3,4 genotype increased in frequency from small to large mussels. All other LAP genotypes occurred at low frequencies (<0.10)
at all three locations and showed no evidence of frequency change from small to large-size mussels nor evidence of clinal
change among the three locations. These genotype frequency data possibly indicate that the Lap
3,3 genotype is at a selective disadvantage compared to the Lap
3,4 genotype at all three locations, and that this selective disadvantage is related to the extent of salinity variation which
exists at each location. Further investigation is required before it can be determined if the Long Island Sound model of selection
best describes the size-dependent and location-specific changes in LAP allele and genotype frequencies along this salinity
gradient. Comparison of the population genetic structure at the LAP locus in 1995 and in 1997 revealed a profound change from
heterozygote excesses to heterozygote deficiencies for all three M. galloprovincialis populations. The reason for the change is unknown, but the change indicates that population genetic structure at the LAP
locus is highly variable in time, but consistent in space, among these M.␣galloprovincialis populations.
Received: 5 February 1998 / Accepted: 27 May 1998 相似文献
12.
Marine communities are experiencing unprecedented rates of species homogenization due to the increasing success of invasive
species, but little is known about the mechanisms that allow a species to invade and persist in a new habitat. In central
California, native (Mytilus trossulus Gould 1850) and invasive (Mytilus galloprovincialis Lamarck 1819) blue mussels and their hybrids co-exist, providing an opportunity to analyze the mechanisms that determine
the distributions of these taxa. Spatial and temporal variation in temperature and salinity and the relative frequencies of
these mussel taxa were examined between 2000 and 2004 at four sites in San Francisco Bay and four in Monterey Bay, which were
chosen for their different positions along inferred estuarine/oceanic gradients in the hybrid zone. Mussels were genetically
identified as the parent species or hybrids by amplifying regions of two species-specific loci: the adhesive byssal thread
protein (Glu-5′) and the internal transcribed spacer region of ribosomal DNA (ITS 1). The proportion of M. trossulus at the eight hybrid zone sites correlated negatively with average salinity (R
2=0.60) and positively with maximal temperature (R
2≥0.72), a somewhat unexpected result given what is known about the phylogeography of this species. The proportion of M. galloprovincialis showed the opposite pattern. The proportion of hybrids was correlated neither with habitat temperature nor salinity. Genotypes
of mussel populations at an additional 13 sites from Coos Bay, Oregon (latitude 43.35°N) to Long Beach, California (latitude
33.72°N), sampled at various intervals between 2000 and 2004, were also determined. This survey confirmed previous reports
that the hybrid zone lies between Monterey and the Cape Mendocino region (latitudes 36.63°N–40.5°N). Within Monterey and San
Francisco Bays, however, the temporal comparisons (1990s vs. 2000s) revealed abrupt changes in the proportions of the two
parent species and their hybrids on annual and decadal time scales. These changes indicate that the blue mussel populations
are in a highly dynamic state. The survey also showed that, regardless of habitat, M. trossulus is consistently of smaller average size than either M. galloprovincialis or hybrids.
相似文献
Caren E. BrabyEmail: |
13.
Within beds of blue mussel (Mytilus edulis L.), individuals are aggregated into small patches, which in turn are incorporated into bigger patches, revealing a complex hierarchy of spatial structure. The present study was done to find the different scales of variation in the distribution of mussel biomass, and to describe the spatial heterogeneity on these scales. The three approaches compared for this purpose were fractal analysis, spatial autocorrelation and hierarchical (or nested) analysis of variances (ANOVA). The complexity (i.e. patchiness) of mussel aggregations was described with fractal dimension, calculated with the semivariogram method. Three intertidal mussel beds were studied on the west coast of Sweden. The distribution of wet biomass was studied along transects up to 128 m. The average biomasses of blue mussels on the three mussel beds were 1825낚, 179ᆩ and 576ᇖ g per0.1 m2, respectively, and the fractal dimensions of the mussel distribution were 1.726ǂ.010, 1.842ǂ.014 and 1.939ǂ.029 on transects 1-3, respectively. Distributions of mussels revealed multiscaling behaviour. The fractal dimension significantly changed twice on different scales on the first bed (thus showing three scaling regions), the second and third beds revealed two and three scaling regions, respectively. High fractal dimension was followed by significant spatial autocorrelation on smaller scales. The fractal analysis detects the multiple scaling regions of spatial variance even when the spatial structure may not be distinguished significantly by conventional statistical inference. The study shows that the fractal analysis, the spatial autocorrelation analysis and the hierarchical ANOVA give complementary information about the spatial variability in mussel populations. 相似文献
14.
Two species of blue mussel, Mytilus galloprovincialis and M. trossulus, co-occur and hybridize along the Pacific coast of North America. Using a set of polymerase chain-reaction (PCR)-based genetic
markers which diagnostically identify these species, we show that they are sympatric from the Cape Mendocino region to the
Monterey Peninsula in northern and central California, USA. Mussels with hybrid genotypes were detected in all populations
sampled in the region of sympatry, and the frequency of hybrid genotypes in individual hybrid populations ranged from 13 to
44%. Significant frequencies of first-generation backcross genotypes were detected in two individual hybrid zone populations
(Berkeley and Monterey Marina) and in the hybrid zone as a whole, indicating that the potential exists for introgression between
M. galloprovincialis and M. trossulus. Despite this potential, we found no evidence of advanced introgression beyond first-generation backcrosses, suggesting that
gene flow between M. galloprovincialis and M. trossulus has been quite limited. The frequency of mussels with M. trossulus and hybrid genotypes declined abruptly south of Monterey Peninsula, while the frequency of mussels with M. galloprovincialis and hybrid genotypes declined precipitously north of Cape Mendocino. These abrupt genetic discontinuities indicate that this
blue mussel hybrid zone is presently positioned between two prominent coastal features and there is little, if any, export
of alleles from the hybrid zone into bordering parental populations.
Received: 20 August 1997 / Accepted: 26 October 1998 相似文献
15.
The blue mussels Mytilus edulis L. and M. galloprovincialis Lmk. hybridize in western Europe. Within hybrid populations nuclear alleles specific to M. galloprovincialis increase in frequency with age and size. This relationship changes with tidal height; alleles from M. galloprovincialis occur more frequently high in the intertidal zone, while M. edulis alleles predominate in the low intertidal zone. We tested the hypotheses that larvae with M. galloprovincialis alleles tend to settle higher in the intertidal zone, or that mussels redistribute themselves with respect to tidal height
after initial larval settlement. We sampled recently metamorphosed mussels every 2 weeks in a hybrid mussel population at
Whitsand Bay in southwest England throughout the summer of 1996. We observed four cohorts of newly settled mussels. There
was no evidence of differential settlement of mussels with different genotypes in connection with tidal height, or into shaded
versus unshaded microsites. Therefore, we rejected the preferential settlement hypothesis. There was substantial movement
of juvenile mussels in the first 4 weeks following initial settlement, but this “secondary settlement” did not result in genetic
differentiation with respect to tidal height. Further, significant differences in allele frequencies were found between primary
and secondary spat. This allele frequency change was in the opposite direction of that seen in the adult population, suggesting
newly settled larvae may be experiencing different selective pressures than adults. We propose that the genetic structure
of hybrid mussel populations with respect to tidal height is the consequence of differences in selection intensity.
Received: 30 April 1999 / Accepted: 5 May 2000 相似文献
16.
M. Peharda C. A. Richardson I. Mladineo S. Šestanović Z. Popović J. Bolotin N. Vrgoč 《Marine Biology》2007,151(2):629-638
Age, growth and population structure of Modiolus barbatus from Mali Ston Bay, Croatia were determined using modal size (age) classes in length frequency distributions, annual pallial
line scars on the inner shell surface, internal annual growth lines in shell sections of the middle nacreous layer and Calcein
marked and transplanted mussels. The length frequency distributions indicated that M. barbatus attain a length of ∼40 mm in 5–6 years indicating that a large proportion of the population in Mali Ston Bay is <5 years
old. Some mussels of ∼60 mm were predicted to be 14 years old using the Von Bertalanffy growth (VBG) equation. Up to the first
6 pallial line scars were visible in young (<6 years) mussels but in older shells the first scars became obscured by nacre
deposition as the mussel increased in length and age. The age of the older shells (>6 years) was determined from the middle
nacreous lines in shell section, which formed annually in winter between February and March; the wider dark increments forming
during summer (June to September). The oldest mussel, determined from the middle nacreous lines, was >12 years, with the majority
of mussels aged between 3 and 6 years of age. The ages of mussels ascertained using the growth lines were not dissimilar to
the ages predicted from the length frequency distributions. Age at length curves produced using modal size class data were
not different from the data obtained using the pallial scar rings and internal growth lines. Taken together these data suggest
that M. barbatus attains a length of 40 and 50 mm within 5 and 8 years, respectively. Eighty one percent of individual M. barbatus injected with a Calcein seawater solution (300 mg Calcein l−1), into their mantle cavity successfully deposited a fluorescent line, which was visible in suitably prepared shell sections
under ultra violet light. Incorporation of Calcein into the mussel shells was seasonally variable with the lowest frequency
of incorporation in mussels marked in February and recovered in May. Seasonal shell growth was observed with significantly
higher growth rates in mussels marked in May and removed in August (ANCOVA, F
3,149 = 23.11, P < 0.001). Mussels (∼18 to 22 mm) marked in May and recovered in August displayed maximal growth rates of >2.5 mm month−1 compared with a mean mussel growth rate of 1.2 ± 0.6 mm month−1. At other times of the year mussel shell growth ranged from immeasurable to 1.48 mm month−1. 相似文献
17.
Many South African populations of the brown mussel Perna perna have been depleted through over-exploitation by subsistence harvesters. This is problematic because recovery after disturbance
is very slow, partly because recruits are largely associated with adult mussels. However, unlike large recruits of 3.5–10 mm
that exhibit spatial structure related to that of adults, a very high proportion of settlers and small recruits (0–3.5 mm)
occur on foliose algae. We tested the hypothesis that recruits on algae move to adult mussel beds after a period of growth,
with the null hypothesis that they die at a certain size. We conducted an indirect field study comparing the ratios of large
to small recruits in 100% cover mussel patches at locations with high and low algal cover. A second laboratory experiment
analysed whether the size of recruits on algae affects their active movement behaviour in response to nearby mussel patches.
Large/small recruit ratios were slightly, but not significantly greater in high than low algal cover locations. Both small
(2–2.5 mm) and medium (4.5–5.5 mm) recruits remained on algae and moved very short distances throughout the laboratory experiment,
while larger recruits (9–10 mm) moved significantly further distances and more often into mussel patches. The results suggest
that very large recruits are able to migrate actively to nearby mussel patches, indicating ontogenetic shifts in this behaviour.
However, the absence of a significant difference in ratios between field locations with high and low algal cover suggests
many large recruits are accidentally dislodged from the algae and presumably die. Thus settlement of P. perna onto algae is likely to be wasted, with consequences for sustainable management of the mussel resource. 相似文献
18.
Simone Cappello Santina Santisi Rosario Calogero Christoph Gertler Francesca Crisafi 《Chemistry and Ecology》2013,29(3):239-252
A number of previous studies have shown that the relationships of symbiosis existing between mussels and microorganisms are directly dependent on the environmental conditions. However, little is known about existing relationships between mussels and bacteria in hydrocarbon-impacted marine environments. The aim of this preliminary study is to investigate the presence of oil-degrading bacteria in the mussel Mytilus galloprovincialis during growth in polluted ecosystems. All the experiments were carried out in a mesocosm system designed to simulate chronic pollution and to enable direct exposure of mussels to chemicals. Quantitative (4′,6-diamidino-2-phenylindole, colony-forming units, Most Probable Number) analyses and screening (presence/absence) of metabolic functional genes were performed to analyse bacterial populations inside the gills of mussels exposed and not exposed to hydrocarbons. The data obtained show that the presence of hydrocarbons affected the abundance of bacteria inside the gills of specimens and determines selection for specific (hydrocarbon-degrading) bacteria (i.e. Alcanivorax sp. and Marinobacter sp.). However, is not yet clear whether the presence of such genera of bacteria inside the mussel is due to symbiosis or as a result of filtration. 相似文献
19.
C. G. N. de Vooys 《Marine Biology》2003,142(6):1119-1123
Aggregation of blue mussels (Mytilus edulis ) is stimulated by environmental chemical stimuli. Experiments carried out in a basin with a one-way current showed that individual mussels were attracted to upstream mussel concentrations and moved actively in their direction. The involvement of a tripeptide in this migration was implicated by experiments demonstrating that individual mussels were effectively attracted and moved actively towards a source of glycine–glycine–arginine at concentrations of 0.56–3.78×10–10 M. A distinct seasonal difference in the extent of movement towards mussel concentrations was found. From the beginning of autumn, movement decreases linearly towards zero movement in winter. 相似文献
20.
Structure and complexity of the substrate are important habitat characteristics for benthic epifauna. The specific growth and mortality rates and inducible defence characters on medium-sized blue mussels (Mytilus edulis L.) exposed to shore crabs (Carcinus maenas L.) were examined on three different substrate types in combined field and laboratory experiments. The experiments showed that complexity of the substrate increased blue mussel survival significantly, through a decrease in predation pressure. However, increased intraspecific competition for food on the complex substrate resulted in significantly lower growth rates of the mussels. Inducible defence characters were also influenced by substrate type. Blue mussels were more affected by predators on the structurally simple substrate, where they developed thicker shells and a larger posterior adductor muscle. 相似文献