1,720,986 research outputs found
Trait-mediated processes and per capita contributions to ecosystem functioning depend on conspecific density and climate conditions
No full textThe ecological consequences of environmental change are highly dependent on the functional contributions of the surviving community, but categorical descriptors commonly used to project ecosystem futures fail to capture context dependant response variability. Here, we show that intraspecific variability for a range of sediment-dwelling marine invertebrates is moderated by changes in the density of conspecifics and/or climatic conditions. Although these trait-mediated changes result in modifications to ecosystem properties, we find that the contributions of individuals to functioning are not necessarily additive but, instead, are a result of alterations to per capita performance. Our findings also indicate that trait variation within species can exert a greater influence on functioning than that of trait variation between species. Hence, projections of likely functional outcomes that scale from mean trait values are unlikely to be robust, highlighting a need to account for how and when intraspecific variability results in context-dependent community responses to change
Intraspecific variability across seasons and geographically distinct populations can modify species contributions to ecosystems
No full text1. Environmental change profoundly alters biodiversity and, by extension, species contributions to ecosystem functioning. While it is well-established that these impacts can be geographically and temporally nuanced, most assessments of species contributions to ecosystems assume that species traits are temporally and spatially fixed, and those that do acknowledge intraspecific variability have failed to fully determine its relevance to ecosystem functioning. 2. Here, using three geographically distinct populations of sediment-dwelling invertebrates, we combined a laboratory experiment with Bayesian hierarchical modelling to empirically quantify the prevalence of intraspecific trait variability in relation to geographic locality and seasonal conditions. Furthermore, we assessed the role of intraspecific trait variability in mediating sediment particle mixing, nutrient generation and benthic oxygen uptake. 3. We found that geographic and seasonal variability in body size and sediment particle reworking modified macrofaunal contributions to sediment total oxygen uptake and nutrient generation. These associations, however, were not consistent across all measured traits and ecosystem functions. 4. Our findings highlight asymmetries in both the absolute magnitude and/or direction of species responses to changing seasonal conditions, indicating that the relative functional contributions species make to ecosystems can be temporally or spatially transient and may, therefore, diverge from expectations based on contemporary functional group typologies. 5. These findings highlight a critical knowledge gap in our understanding of the key sources of variability affecting functionally important aspects of species behaviour and physiology and call for the development of dynamic ecological assessment and management approaches that account for individual, as well as species, responses to changing environments.<br/
Mytilus hybridisation and impact on aquaculture: A minireview
No full textThe three species in the blue mussel complex (Mytilus edulis, Mytilus galloprovincialis and Mytilus trossulus) show varying levels of hybridisation wherever they occur sympatrically. The spatial variation in hybridisation patterns is potentially governed by environmental conditions, larval dispersal and aquaculture practices. Commercial mussel cultivation has been shown to increase hybridisation through introduction of non-native species or spat transfer. There is evidence that mussel cultivation may promote commercially less desirable phenotypes (e.g. fragile shells), however, to what extent hybridisation impacts aquaculture is currently not clear. The aim of this review is to summarize the available information on Mytilus hybridisation patterns in Europe and their promotion through aquaculture practices in order to shed light on the overall implications for the aquaculture industry
Environmental hypoxia but not minor shell damage affects scope for growth and body condition in the blue mussel Mytilus edulis (L.)
No full textThe effects of short-term (7 d) exposure to environmental hypoxia (2.11 mg O-2 L-1; control: 6.96 mg O-2 L-1) and varying degrees of shell damage (1 or 2, 1 mm diameter holes; control: no holes) on respiration rate, clearance rate, ammonia excretion rate, scope for growth (SFG) and body condition index were investigated in adult blue mussels (Mytilus edulis). There was a significant hypoxia-related reduction in SFG (>6.70 to 0.92J g(-1) h(-1)) primarily due to a reduction in energy acquisition as a result of reduced clearance rates during hypoxia. Shell damage had no significant affect on any of the physiological processes measured or the SFG calculated. Body condition was unaffected by hypoxia or shell damage. In conclusion, minor physical damage to mussels had no effect on physiological energetics but environmental hypoxia compromised growth, respiration and energy acquisition presumably by reducing feeding rates
High Calcification Costs Limit Mussel Growth at Low Salinity
Full text linkIn coastal temperate regions such as the Baltic Sea, calcifying bivalves dominate benthic communities playing a vital ecological role in maintaining biodiversity and nutrient recycling. At low salinities, bivalves exhibit reduced growth and calcification rates which is thought to result from physiological constraints associated with osmotic stress. Calcification demands a considerable amount of energy in calcifying molluscs and estuarine habitats provide sub-optimal conditions for calcification due to low concentrations of calcification substrates and large variations in carbonate chemistry. Therefore, we hypothesize that slow growth rates in estuarine bivalves result from increased costs of calcification, rather than costs associated with osmotic stress. To investigate this, we estimated the cost of calcification for the first time in benthic bivalve life stages and the relative energy allocation to calcification in three Mytilus populations along the Baltic salinity gradient. Our results indicate that calcification rates are significantly reduced only in 6 psu populations compared to 11 and 16 psu populations, coinciding with ca. 2–3-fold higher calcification costs at low salinity and temperature. This suggests that reduced growth of Baltic Mytilus at low salinities results from increased calcification costs rather than osmotic stress related costs. We also reveal that shell growth (both calcification and shell organic production) demands 31–60% of available assimilated energy from food, which is significantly higher than previous estimates. Energetically expensive calcification represents a major constraint on growth of mytilids in the estuarine and coastal seas where warming, acidification and desalination are predicted over the next century
Decoupling salinity and carbonate chemistry: Low calcium ion concentration rather than salinity limits calcification in Baltic Sea mussels
Full text linkThe Baltic Sea has a salinity gradient decreasing from fully marine (> 25) in the west to below 7 in the central Baltic Proper. Habitat-forming and ecologically dominant mytilid mussels exhibit decreasing growth when salinity < 11; however, the mechanisms underlying reduced calcification rates in dilute seawater are not fully understood. Both [HCO−3] and [Ca2+] also decrease with salinity, challenging calcifying organisms through CaCO3 undersaturation (Ω≤1) and unfavourable ratios of calcification substrates ([Ca2+] and [HCO−3]) to the inhibitor (H+), expressed as the extended substrate–inhibitor ratio (ESIR). This study combined in situ monitoring of three southwest Baltic mussel reefs with two laboratory experiments to assess how various environmental conditions and isolated abiotic factors (salinity, [Ca2+], [HCO−3] and pH) impact calcification in mytilid mussels along the Baltic salinity gradient. Laboratory experiments rearing juvenile Baltic Mytilus at a range of salinities (6, 11 and 16), HCO−3 concentrations (300–2100 µmol kg−1) and Ca2+ concentrations (0.5–4 mmol kg−1) reveal that as individual factors, low [HCO−3], pH and salinity cannot explain low calcification rates in the Baltic Sea. Calcification rates are impeded when Ωaragonite ≤ 1 or ESIR ≤ 0.7 primarily due to [Ca2+] limitation which becomes relevant at a salinity of ca. 11 in the Baltic Sea. Field monitoring of carbonate chemistry and calcification rates suggest increased food availability may be able to mask the negative impacts of periodic sub-optimal carbonate chemistry, but not when seawater conditions are permanently adverse, as observed in two Baltic reefs at salinities < 11. Regional climate models predict a rapid desalination of the southwest and central Baltic over the next century and potentially a reduction in [Ca2+] which may shift the distribution of marine calcifiers westward. It is therefore vital to understand the mechanisms by which the ionic composition of seawater impacts bivalve calcification for better predicting the future of benthic Baltic ecosystems
Calcification in a marginal sea - influence of seawater [Ca2+] and carbonate chemistry on bivalve shell formation
No full textIn estuarine coastal systems such as the Baltic Sea, mussels suffer from low salinity which limits their distribution. Anthropogenic climate change is expected to cause further desalination which will lead to local extinctions of mussels in the low saline areas. It is commonly accepted that mussel distribution is limited by osmotic stress. However, along the salinity gradient environmental conditions for biomineralization are successively becoming more adverse as a result of reduced [Ca2+] and dissolved inorganic carbon (CT) availability. In larvae, calcification is an essential process starting during early development with formation of the prodissoconch I (PD I) shell which is completed under optimal conditions within 2 days.
Experimental manipulations of seawater [Ca2+] start to impair PD I formation in Mytilus larvae at concentrations below 3 mM, which corresponds to conditions present in the Baltic at salinities below 8 g kg-1. In addition, lowering dissolved inorganic carbon to critical concentrations (< 1 mM) similarly affected PD I size which was well correlated with calculated ΩAragonite and [Ca2+][HCO3-]/[H+] in all treatments. Comparing results for larvae from the western Baltic with a population from the central Baltic revealed significantly higher tolerance of PD I formation to lowered [Ca2+] and [Ca2+][HCO3-]/[H+] in the low saline adapted population. This may result from genetic adaptation to the more adverse environmental conditions prevailing in the low saline areas of the Baltic.
The combined effects of lowered [Ca2+] and adverse carbonate chemistry represent major limiting factors for bivalve calcification and can thereby contribute to distribution limits of mussels in the Baltic Sea
Systematic review and meta-analysis investigating osmolyte concentrations of marine osmoconformers under low salinity stress
No full textClimate change is predicted to alter salinity in many coastal regions. This exerts significant physiological stress on coastal invertebrates whose body fluid osmolality follows that of seawater ('osmoconformers'). Osmolytes are the cellular actors in osmoconformers that regulate acclimation to salinity changes. Inspite of their cellular importance in salinity tolerance, cellular volume regulation and its osmotic components, are not sufficiently understood. Which compounds are commonly used as osmolytes? Are inorganic and organic osmolytes used in long-term salinity acclimation? Are there taxonomic- or tissue specific differences? By conducting an extensive literature search, this study aimed to answer these questions. By using a meta-analysis approach over an ordinary literature review we were able to statistically evaluate the individual effect sizes by computing a summary effect for multiple studies to estimate the mean of the distribution of the true effect sizes. Meta-analysis is useful to reveal research gaps, common actors across taxa, or overall effects of biotic factors.
We thus conducted a systematic review and meta-analysis of osmolyte data (both organic and inorganic) utilized by osmoconforming marine invertebrates during a >14-day acclimation to reduced salinity. This study offers a valuable overview of the various listed organic compounds across species and whether and in which organisms they are used as osmolytes under low salinity stress. This study thereby creates a valuable baseline for future research.
2389 studies were screened according to standard systematic review procedures (title scan, abstract scan and full-exam) resulting a total of 56 studies that fulfilled the search criteria. The data includes the list of all papers that underwent a full-exam in the systematic review process and passed the search criteria and study details of the studies used for meta-analysis. For all included studies the input data necessary to conduct a meta-analysis with a hedge's g effect size is given. Namely, mean osmolyte concentrations, variance measure and replicate numbers are given for the high and low salinity treatment. The data for any benthic osmoconforming species and any osmolyte type is included. The data table is sorted by study but gives additional information on taxonomy, experimental details, study design, osmolyte type, tissue type, etc.
Additionally, data is available for a number of studies that reported an extensive osmolyte budget (i.e. multiple compounds). Here, for each study and study organism osmolytes (that were present in more than one study) are listed as percent of the total organic osmolyte pool.
This dataset is the first systematically compiled list of studies investigating osmolyte concentrations in osmoconformers after long-term (>14 days) acclimation to low salinity. Data can be used to compare own osmolyte data (species/osmolyte compound) with a comprehensive list of osmolyte literature data. Additionally, this data can be used to address other hypotheses via meta-analysis.
As this was a systematic review, no biological samples were collected in this study. Information of the origin of the data from each of the included studies can be found in the list of all included studies
Infestation of shore crab gills by a free-living mussel species
Full text linkParasitic and commensal species can impact the structure and function of ecological communities and are typically highly specialized to overcome host defences. Here, we report multiple instances of a normally free-living species, the blue mussel Mytilus edulis Linnaeus, 1758, inhabiting the branchial chamber of the shore crab Carcinus maenas (Linnaeus, 1758) collected from widely separated geographical locations. A total of 127 C. maenas were examined from four locations in the English Channel, one location in the Irish Sea and two locations at the entrance of the Baltic Sea. The branchial chambers of three crabs (one from the English Channel and two from Gullmar Fjord, Sweden) were infested with mussels resembling the genus Mytilus. Sequencing at the Me15/16 locus on the polyphenolic adhesive protein gene confirmed the identity as M. edulis. Bivalve infestation always occurred in larger red male individuals. Up to 16 mussels, ranging from 2 to 11 mm in shell length, were found in each individual, either wedged between gill lamellae or attached to the branchial chamber inner wall. This is one of the first reports of a bivalve inhabiting crustacean gills and is an intriguing case of a normally free-living prey species infesting its predato
Blue mussel shell shape plasticity and natural environments: a quantitative approach
Full text linkShape variability represents an important direct response of organisms to selective environments. Here, we use a combination of geometric morphometrics and generalised additive mixed models (GAMMs) to identify spatial patterns of natural shell shape variation in the North Atlantic and Arctic blue mussels, Mytilus edulis and M. trossulus, with environmental gradients of temperature, salinity and food availability across 3980 km of coastlines. New statistical methods and multiple study systems at various geographical scales allowed the uncoupling of the developmental and genetic contributions to shell shape and made it possible to identify general relationships between blue mussel shape variation and environment that are independent of age and species influences. We find salinity had the strongest effect on the latitudinal patterns of Mytilus shape, producing shells that were more elongated, narrower and with more parallel dorsoventral margins at lower salinities. Temperature and food supply, however, were the main drivers of mussel shape heterogeneity. Our findings revealed similar shell shape responses in Mytilus to less favourable environmental conditions across the different geographical scales analysed. Our results show how shell shape plasticity represents a powerful indicator to understand the alterations of blue mussel communities in rapidly changing environments
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