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- Chauvaud, L., et al.
(författare)
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Variation in Size and Growth of the Great Scallop Pecten maximus along a Latitudinal Gradient
- 2012
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the relationship between growth and temperature will aid in the evaluation of thermal stress and threats to ectotherms in the context of anticipated climate changes. Most Pecten maximus scallops living at high latitudes in the northern hemisphere have a larger maximum body size than individuals further south, a common pattern among many ectotherms. We investigated differences in daily shell growth among scallop populations along the Northeast Atlantic coast from Spain to Norway. This study design allowed us to address precisely whether the asymptotic size observed along a latitudinal gradient, mainly defined by a temperature gradient, results from differences in annual or daily growth rates, or a difference in the length of the growing season. We found that low annual growth rates in northern populations are not due to low daily growth values, but to the smaller number of days available each year to achieve growth compared to the south. We documented a decrease in the annual number of growth days with age regardless of latitude. However, despite initially lower annual growth performances in terms of growing season length and growth rate, differences in asymptotic size as a function of latitude resulted from persistent annual growth performances in the north and sharp declines in the south. Our measurements of daily growth rates throughout life in a long-lived ectothermic species provide new insight into spatio-temporal variations in growth dynamics and growing season length that cannot be accounted for by classical growth models that only address asymptotic size and annual growth rate.
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- Praetorius, A., et al.
(författare)
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Strategies for determining heteroaggregation attachment efficiencies of engineered nanoparticles in aquatic environments
- 2020
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Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 7:2, s. 351-367
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Tidskriftsartikel (refereegranskat)abstract
- Heteroaggregation of engineered nanoparticles (ENPs) with suspended particulate matter (SPM) ubiquitous in natural waters often dominates the transport behaviour and overall fate of ENPs in aquatic environments. In order to provide meaningful exposure predictions and support risk assessment for ENPs, environmental fate and transport models require quantitative information about this process, typically in the form of the so-called attachment efficiency for heteroaggregation alpha(hetero). The inherent complexity of heteroaggregation-encompassing at least two different particle populations, various aggregation pathways and several possible attachment efficiencies (alpha values)-makes its theoretical and experimental determination challenging. In this frontier review we assess the current state of knowledge on heteroaggregation of ENPs with a focus on natural surface waters. A theoretical analysis presents relevant equations, outlines the possible aggregation pathways and highlights different types of alpha. In a second part, experimental approaches to study heteroaggregation and derive alpha values are reviewed and three possible strategies are identified: i) monitoring changes in size, ii) monitoring number or mass distribution and iii) studying indirect effects, such as sedimentation. It becomes apparent that the complexity of heteroaggregation creates various challenges and no single best method for its assessment has been developed yet. Nevertheless, many promising strategies have been identified and meaningful data can be derived from carefully designed experiments when accounting for the different concurrent aggregation pathways and clearly stating the type of alpha reported. For future method development a closer connection between experiments and models is encouraged.
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