Amnesic shellfish poisoning in the king scallop, Pecten maximus, from the west coast of Scotland

Copyright © 2001 D.A. Campbell et al. This is distributed under the Creative Commons Attribution License, which permits use provided the original work is properly cited. Peer reviewed.The king scallop, Pecten maximus, is a valuable economic resource in the UK. The industry relies on supplying premium "roe-on" processed scallops to the continental market. In July 1999, king scallops harboring the amnesic shellfish poisoning (ASP) toxin, domnic acid (DA), in gonadal tissue at levels above the regulatory limit (20 μg DA g-1) were detected across a wide area of northern and western Scotland. In response, a survey of the southern extent of the closed harvest areas was initiated to describe variability of ASP toxin levels over varying spatial scales (5 km); determine the anatomical distribution of the toxin, and identify, isolate, and culture causative Pseudo-nitzschia species. Toxin analysis was conducted using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) procedure. The DA content of tissues followed the predictable rank order: all other tissue -1 gonad -1 adductor. The toxin levels within all other tissue (95% Cl = 580-760 μg DA g-1, n = 170) consistently accounted for 99% of the total individual toxin burden. DA levels in the gonad (95% CI = 8.2-11.0 μg DA g- 1, n = 170) were an order of magnitude below levels in all other tissue and contributed to less than 0.5% of the total individual toxin burden, although levels above the regulatory limit were detected in individual gonad samples. Adductor muscle tissue contained the lowest concentration of DA (95% Cl = 0.38-0.82 μg DA g- 1, n = 170), and was typically within two to three orders of magnitude below levels in all other tissue. None of the scallops examined had DA toxicities in adductor muscle tissue exceeding the regulatory limit. Toxin variability among individuals and sites was high (range of coefficients of variation (CV) in all other tissue = 29&-l20% and gonadal = 45%-85%). The results do give an indication of the scale on which microhabitat differences may influence ASP toxicity in P. maximus populations, because significant differences were found in all other and gonadal tissue toxin levels between groups of individuals only 25-m apart. In total, seven species of Pseudo-nitzschia were identified from west coast waters. A suspected causative species, P. australis, was found to produce high levels of DA, in culture. The high individual variation in toxicities and the occurrence of DA in the gonad at levels above the regula1ory limit clearly demonstrate the complexity of managing the king scallop fishery during ASP events.The Scallop Association, the Highlands and Islands Enterprise, PESCA, and the Highland Council

Interactions between arbuscular mycorrhizal fungi and intraspecific competition affect size and size inequality of Plantago lanceolata L.

Intraspecific competition causes decreases in plant size and increases in size inequality. Arbuscular mycorrhizas usually increase the size and inequality of non-competing plants, but mycorrhizal effects often disappear when plants begin competing. We hypothesized that mycorrhizal effects on size inequality would be determined by the experimental conditions, and conducted simultaneous field and glasshouse experiments to investigate how AM fungi and intraspecific competition determine size inequality in Plantago lanceolata. 2 As predicted, plant size was reduced when plants were competing, in both field and controlled conditions. However, size inequality was unexpectedly reduced by competition. Plants may have competed in a symmetric fashion, probably for nutrients, rather than the more common situation, in which plant competition is strongly asymmetric. 3 Mycorrhizas had no effect on plant size or size inequality in competing plants in either field or controlled conditions, possibly because competition for nutrients was intense and negated any benefit the fungi could provide. 4 The effects of mycorrhizas on non-competing plants were also unexpected. In field-grown plants, AM fungi increased plant size, but decreased size inequality: mycorrhizal plants were more even in size, with few very small individuals. In glasshouse conditions, mycorrhizal colonization was extremely high, and was generally antagonistic, causing a reduction in plant size. Here, however, mycorrhizas caused an increase in size inequality, supporting our original hypothesis. This was because most plants were heavily colonized and small, but a few had low levels of colonization and grew relatively large. 5 This study has important implications for understanding the forces that structure plant communities. AM fungi can have a variety of effects on size inequality and thus potentially important influences on long-term plant population dynamics, by affecting the genetic contribution of individuals to the next generation. However, these effects differ, depending on whether plants are competing or not, the degree of mycorrhizal colonization and the responsiveness of the plant to different colonization densities

Global hindcasts and future projections of coastal nitrogen and phosphorus loads due to shellfish and seaweed aquaculture

A model was developed to estimate nitrogen and phosphorus budgets for aquaculture production of crustaceans, bivalves, gastropods, and seaweed, using country production data for the 1970–2006 period from the Food and Agriculture Organization and scenarios based on the Millenium Assessment for 2006–2050. Global production of crustaceans (18% yr−1), molluscs (7.4%), and seaweed (8%) increased rapidly during the 1970–2006 period. Scenarios indicate that annual nutrient release from all shellfish (crustaceans, bivalves, and gastropods) aquaculture will rapidly grow from 0.4 to up to 1.7 million tonnes of nitrogen and from 0.01 to 0.3 million tonnes of phosphorus between 2006 and 2050. The nitrogen and phosphorus releases from global freshwater shellfish aquaculture will increase from 1% of river export in 2006 to up to 6% in 2050. Marine shellfish production is an important contributor to nutrient loading of coastal seas, particularly in Eastern Asia. Nitrogen (7% of marine aquaculture + river export in 2006 and up to 19% in 2050) and phosphorus (12% in 2006 and up to 30% in 2050) releases from Chinese marine shellfish aquaculture are important and growing contributors to total nutrient inputs to coastal seas. Production of crustaceans and bivalves causes changes in nutrient stoichiometry and increasing reduced and organic nitrogen forms, which are of concern because of their preferential use by some harmful algae. Nutrient withdrawal by seaweed is projected to increase rapidly over the coming decades. To overcome effects of increasing nutrient release from shellfish production, integrated systems that include seaweed may play an important role in reducing this nutrient load

Peer review: journal articles versus research proposals

The focus of this Theme Section is peer review of journal manuscripts versus that of research proposals, both of which can be intellectually rewarding. A number of well-established scientists who were invited for comments underlined that whereas a manuscript submitted to a journal is a completed piece of work, suitable to be peer reviewed using well-defined criteria, a research proposal is a plan of action and not an end product in itself, and so requires different assessment criteria. Although it is often transparent how reviewers’ comments on a manuscript are translated into editorial decisions, this may not always be the case with the verdicts of funding agencies on research proposals. Financial compensation may play a role in the willingness of reviewers to undertake the task, and most (but not all) of the scientists thought that such remuneration would be a fair reward. Compensation may be a practical incentive for reviewers who are not citizens of the country served by a particular funding agency, and who are excluded from applying for related funds. Grant awarding agencies in different countries should compare their procedures to assess the merits of different approaches to assessing research proposals