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Papers by Sarah Swan

ABSTRACT Sagittal otoliths of Coryphaenoides rupestris(roundnose grenadier), Helicolenus dactylop... more ABSTRACT Sagittal otoliths of Coryphaenoides rupestris(roundnose grenadier), Helicolenus dactylopterus(bluemouth) and Merluccius merluccius(European hake) were collected using a variety of handling and storage treatments and their elemental composition was examined using inductively coupled plasma mass spectrometry. Some differences between element concentrations were identified between the control and treatment groups, most notably for the element Li. For H. dactylopterus and M. merluccius, Li concentrations were significantly higher in the otoliths extracted with metal forceps and stored in paper envelopes (treatment), compared to those from the same fishes that had been extracted using plastic forceps and stored in polyethylene vials (control). Lower concentrations of Ba and Cr were found in M. merluccius otoliths extracted from fish that had been stored frozen. The presence or absence of elemental concentrations above the instrumental limits of detection was noted, but no significant differences were identified between otolith pairs for any of the treatments. The differences between otolith pairs attributable to storage and handling effects are small compared to between-area differences. (c) 2006 The Fisheries Society of the British Isles.

Risk assessment of the Scottish monitoring programme for the marine biotoxins in shellfish harves... more Risk assessment of the Scottish monitoring programme for the marine biotoxins in shellfish harvested from classified production areas Holtrop,

Harmful algae, 2018

Official control biotoxin testing of bivalve molluscs from Great Britain has been conducted by Ce... more Official control biotoxin testing of bivalve molluscs from Great Britain has been conducted by Cefas for over a decade. Reflecting the changes in legislation, bioassays were gradually replaced by analytical methods, firstly for analysis of Paralytic shellfish toxins, followed by introduction of liquid chromatography tandem mass spectrometric (LCMS/MS) method for lipophilic toxins (LTs) in 2011. Twelve compounds, representing three main groups of regulated lipophilic toxins, as well as two non-regulated cyclic imines were examined in over 20,500 samples collected between July 2011 and December 2016. The toxins belonging to Okadaic acid (OA) group toxins were the most prevalent and were quantified in 23% of samples, predominantly from Scotland. The temporal pattern of OA group occurrences remained similar each year, peaking in summer months and tailing off during autumn and winter, however their abundance and magnitude varied between years significantly, with concentrations reaching u...

Centro Oceanográfico de Vigo, 2000

Publicado

Frontiers in Marine Science, 2021

Consistent patterns of Harmful Algal Bloom (HAB) events are not evident across the scientific lit... more Consistent patterns of Harmful Algal Bloom (HAB) events are not evident across the scientific literature, suggesting that local or regional variability is likely to be important in modulating any overall trend. This study summarizes Scotland-wide temporal and spatial patterns in a robust 15-year high temporal frequency time series (2006–2020) of the incidence of HABs and shellfish biotoxins in blue Mussels (Mytilus edulis), collected as part of the Food Standards Scotland (FSS) regulatory monitoring program. The relationship between the countrywide annual incidence of HAB events and biotoxins with environmental variables was also explored. Temporal patterns exhibited interannual variability, with no year-on-year increase, nor any correlation between annual occurrences. Within years, there was a summer increase in bloom frequency, peaking in July for Dinophysis spp. and Pseudo-nitzschia spp., and a plateau from May to July for Alexandrium spp. Temporal-spatial patterns were analyzed ...

Harmful Algae, 2021

The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and s... more The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies 'Dinophysis acuminata complex' and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Harmful Algae, 2019

Variability of Amnesic Shellfish Toxin and Pseudo-nitzschia occurrence in bivalve molluscs and wa... more Variability of Amnesic Shellfish Toxin and Pseudo-nitzschia occurrence in bivalve molluscs and water samples-Analysis of ten years of the official control monitoring programme

Journal of Northwest Atlantic Fishery Science, 2003

The black scabbardfish (Aphanopus carbo: family Trichiuridae) is widely distributed in the North ... more The black scabbardfish (Aphanopus carbo: family Trichiuridae) is widely distributed in the North Atlantic at depths between about 700 and 1 000 m. There is a long-established longline fishery off the island of Madeira, and another that began off mainland Portugal in 1983. It is an important species in the landings from the mixed bottom trawl fishery that developed in the Rockall Trough in the 1990s. The stock composition of this species is unknown, as are the eggs, larvae and smallest juveniles. Length composition and reproductive maturity vary between areas and these were among the criteria that led the ICES Deep-water Study Group to carry out preliminary assessments on tentative southern and northern stocks. An objective of the BASBLACK Project (EC DG Fisheries 97/0084) was to investigate stock discrimination in this species. The hypothesis to be tested was that there is one stock of black scabbardfish, which has a main spawning area in the south and a sub-adult feeding area in the north. One method used was otolith microchemistry and this paper describes the methodology and some of the results. The elemental composition of the otoliths was determined using solution-based ICP-MS. The method used to minimize suppression or enhancement effects of the otolith matrix is described. Multivariate analysis was used to compare the results between areas, after taking into account possible differences in element concentration associated with fish length. Although the results are inconclusive, they suggest that this could be a useful technique for this species.

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Toxins, Jan 28, 2018

Diarrhetic shellfish toxins produced by the dinoflagellate genus are a major problem for the shel... more Diarrhetic shellfish toxins produced by the dinoflagellate genus are a major problem for the shellfish industry worldwide. Separate species of the genus have been associated with the production of different analogues of the okadaic acid group of toxins. To evaluate the spatial and temporal variability of species and toxins in the important shellfish-harvesting region of the Scottish west coast, we analysed data collected from 1996 to 2017 in two contrasting locations: Loch Ewe and the Clyde Sea. Seasonal studies were also undertaken, in Loch Ewe in both 2001 and 2002, and in the Clyde in 2015. was present throughout the growing season during every year of the study, with blooms typically occurring between May and September at both locations. The appearance of was interannually sporadic and, when present, was most abundant in the late summer and autumn. The Clyde field study in 2015 indicated the importance of a temperature front in the formation of a bloom. A shift in toxin profiles...

Harmful Algae, 2017

Fjordic coastlines provide an ideal protected environment for both finfish and shellfish aquacult... more Fjordic coastlines provide an ideal protected environment for both finfish and shellfish aquaculture operations. This study reports the results of a cruise to the Scottish Clyde Sea, and associated fjordic sea lochs, that coincided with blooms of the diarrhetic shellfish toxin producing dinoflagellate Dinophysis acuta and the diatom genus Chaetoceros, that can generate finfish mortalities. Unusually, D. acuta reached one order of magnitude higher cell abundance in the water column (2840 cells L-1) than the more common Dinophysis acuminata (200 cells L-1) and was linked with elevated shellfish toxicity (maximum 601 ± 237 μg OA eq/kg shellfish flesh) which caused shellfish harvesting closures in the region. Significant correlations between D. acuta abundance and that of Mesodinium rubrum were also observed across the cruise transect potentially supporting bloom formation of the mixotrophic D. acuta. Significant spatial variability in phytoplankton that was related to physical characteristics of the water column was observed, with a temperature-driven frontal region at the mouth of Loch Fyne being important in the development of the D. acuta, but not the Chaetoceros bloom. The front also provided significant protection to the aquaculture located within the loch, with neither of the blooms encroaching within it. Analysis based on a particle-tracking model confirms the 2 importance of the front to cell transport and shows significant inter-annual differences in advection within the region, that are important to the harmful algal bloom risk therein.