| 1. |
- Carey, N, et al.
(författare)
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One size fits all: stability of metabolic scaling under warming and ocean acidification in echinoderms
- 2014
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 161:9, s. 2131-2142
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Tidskriftsartikel (refereegranskat)abstract
- Responses by marine species to ocean acidification (OA) have recently been shown to be modulated by external factors including temperature, food supply and salinity. However the role of a fundamental biological parameter relevant to all organisms, that of body size, in governing responses to multiple stressors has been almost entirely overlooked. Recent consensus suggests allometric scaling of metabolism with body size differs between species, the commonly cited ‘universal’ mass scaling exponent (b) of ¾ representing an average of exponents that naturally vary. One model, the Metabolic-Level Boundaries hypothesis, provides a testable prediction: that b will decrease within species under increasing temperature. However, no previous studies have examined how metabolic scaling may be directly affected by OA. We acclimated a wide body-mass range of three common NE Atlantic echinoderms (the sea star Asterias rubens, the brittlestars Ophiothrix fragilis and Amphiura filiformis) to two levels of pCO2 and three temperatures, and metabolic rates were determined using closed-chamber respirometry. The results show that contrary to some models these echinoderm species possess a notable degree of stability in metabolic scaling under different abiotic conditions; the mass scaling exponent (b) varied in value between species, but not within species under different conditions. Additionally, we found no effect of OA on metabolic rates in any species. These data suggest responses to abiotic stressors are not modulated by body size in these species, as reflected in the stability of the metabolic scaling relationship. Such equivalence in response across ontogenetic size ranges has important implications for the stability of ecological food webs.
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| 2. |
- 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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| 3. |
- Dupont, Samuel, 1971, et al.
(författare)
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Near Future Ocean Acidification Increases Growth Rate of the Lecithotrophic Larvae and Juveniles of the Sea Star Crossaster papposus
- 2010
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Ingår i: Journal of Experimental Zoology Part B-Molecular and Developmental Evolution. - 1552-5007. ; 314B:5, s. 382-389
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification (OA) is believed to be a major threat for near-future marine ecosystems, and that the most sensitive organisms will be calcifying organisms and the free-living larval stages produced by most benthic marine species. In this respect, echinoderms are one of the taxa most at risk. Earlier research on the impact of near-future OA on echinoderm larval stages showed negative effects, such as a decreased growth rate, increased mortality, and developmental abnormalities. However, all the long-term studies were performed on planktotrophic larvae while alternative life-history strategies, such as nonfeeding lecithotrophy, were largely ignored. Here, we show that lecithotrophic echinoderm larvae and juveniles are positively impacted by ocean acidification. When cultured at low pH, larvae and juveniles of the sea star Crossaster papposus grow faster with no visible affects on survival or skeletogenesis. This suggests that in future oceans, lecithotrophic species may be better adapted to deal with the threat of OA compared with planktotrophic ones with potentially important consequences at the ecosystem level. For example, an increase in populations of the top predator C. papposus will likely have huge consequences for community structure. Our results also highlight the importance of taking varying life-history strategies into account when assessing the impacts of climate change, an approach that also provides insight into understanding the evolution of life-history strategies. J. Exp. Zool. (Mol. Dev. Evol) 314B:382-389, 2010. (C) 2010 Wiley-Liss, Inc.
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| 4. |
- Lindahl, Odd, et al.
(författare)
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Toxicity of Dinophysis spp. in relation to population density and environmental conditions on the Swedish west coast
- 2007
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Ingår i: Harmful Algae. - 1568-9883. ; 6:2, s. 218-231
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study in the field was to investigate whether there are differences between the outer archipelago (Gullmar Fjord) and a semi-enclosed fjord system (Koljo Fjord) in occurrences of D. acuta and D. acuminata as well as in their content of diarrheic shellfish toxin (DST) per cell. When all data pairs of cell toxicity of D. acuminata and the corresponding number of cells l(-1) from the two sites were tested in a regression analysis, a statistically significant negative correlation became evident and was apparent as a straight line on a log-log plot (p < 0.0001). Obviously, there was an overall inverse relationship between the population density of D. acuminata and the toxin content per cell. Plotted on a linear scale, all data-pairs of cell toxicity and cell number made up a parabolic curve. On this curve the data-pairs could be separated into three groups: (i) D. acuminata occurring in numbers of fewer than approximately 100 cells l(-1), and with a toxin content per cell above 5 rho g cell(-1); (ii) cell numbers between 100 and approximately 250 cells l(-1) with a cell toxin content from 5 to 2 rho g cell(-1); (iii) when the population became greater than 250 cells l(-1), the toxicity, with few exceptions, was less than 2 rho g cell(-1). By applying this subdivision, some clear patterns of the distribution of the differently toxic D. acuminata became evident. When comparing the cell toxicity of the two sites, it was obvious that the D. acuminata cells from all depths from the Gullmar Fjord as a mean were significantly more toxic compared to the Koljo Fjord samples. The results have demonstrated that approximately 100 high-toxicity cells in a low-density population at surface may lead to the same accumulation of DST in a mussel as the ingestion of 1500 low-toxicity cells from a high-density pycnocline population. (c) 2006 Elsevier B.V. All rights reserved.
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| 5. |
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| 6. |
- Torgersen, T., et al.
(författare)
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Profiles and levels of fatty acid esters of okadaic acid group toxins and pectenotoxins during toxin depuration. Part II: Blue mussels (Mytilus edulis) and flat oyster (Ostrea edulis)
- 2008
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Ingår i: Toxicon. - : Elsevier BV. - 0041-0101. ; 52:3, s. 418-427
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Tidskriftsartikel (refereegranskat)abstract
- Bivalve molluscs accumulate toxins of the okadaic acid (OA) and pectenotoxin (PTX) groups, which are frequently found in Dinophysis spp. Transformation of the OA-group toxins into fatty acid ester derivatives (often designated "DTX3") is common in many bivalve species but the degree to which these toxins are transformed vary between species, and is also depending on the parent toxin involved. In this paper, detailed profiles and levels of fatty acid esters of OA, DTX1, DTX2 and PTX2 SA were studied in blue mussels (Mytilus edulis) and European flat oysters (Ostrea edulis), collected during a bloom of Dinophysis spp. and after 3 and 6 weeks of depuration. Analysis of samples by HPLC-MS/MS and HPLC-MS2 revealed some differences in identity and abundance of fatty acid moieties of the OA-group esters between species, but the 16:0 fatty acid esters dominated in both oysters and mussels, which is in accordance with the free fatty acid profiles in these species. A wider range of FM SA-esters were detected compared to esters of the CA-group toxins in both mussels and oysters, and in oysters, both 14:0, 18:4 and 20:5 fatty acid side chains were more common than 16:0. OA-group toxins were esterified to a larger degree in oysters (83-93%) compared to mussels (21-41%), and in mussels a higher proportion of OA was esterified compared to DTX1 and DTX2. Contrary to what was observed for CA-group toxins, PTX2 SA was esterified to a larger degree in mussels (81%) compared to oysters (64%). Calculations of depuration rates for all individual esters of each parent compound showed that the esters of DTX1 depurated significantly slower from both mussels and oysters compared to esters of OA, DTX2 and PTX2 SA, but overall the deputation rates of esters of both toxin group were highly similar for both species. This indicated that differences in depuration rates are not causing the large species-specific differences in levels and profiles of these toxins. Instead, the results for the CA-group toxins suggested that a higher rate of esterification in oysters is the main factor causing the observed differences in the proportion of esters to free toxin. For FM SA, large differences in ester profiles and a higher proportion of esters of PTX2 SA in mussels compared to oysters suggested differential assimilation and metabolic rate processes for the PTXs compared to OA-group toxins between these species. Hence, although produced by the same Dinophysis species, conclusions about the dynamics of one toxin group based on results from the other group should be avoided in future studies. (C) 2008 Elsevier Ltd. All rights reserved.
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