Harvesting Closures Research Articles

Seasonal Early Warning of Impacts of Harmful Algal Blooms on Farmed Shellfish in Coastal Waters of Scotland

AbstractHarmful Algal Blooms (HABs) can produce phycotoxins that accumulate in shellfish and subsequently poison aquatic predators and human consumers, potentially causing significant economic impacts to the shellfish aquaculture industry. HAB events are challenging to foresee as they are driven by complex inter‐annual and seasonal changes in physical, chemical and biological factors. Accounting for these environmental drivers and their interactions in statistical models allows for the development of HAB early warning systems. Typically, these have a forecasting horizon of 1–2 weeks, allowing shellfish businesses and regulators to increase monitoring intensity and take evasive action, including harvesting suspensions to protect consumer health. However, there is critical need for longer‐term predictions of risk, to enable more proactive mitigation, business planning, harvest scheduling and supply chain management. We present a statistical framework for providing seasonal‐scale early warnings of the occurrence and impacts of Dinophysis spp. HABs on shellfish aquaculture in Scotland, UK. We use penalized smooth functions of winter‐spring daily sea surface temperature to predict the severity and impact of ensuing summer blooms, including the percentage of toxicity measurements exceeding the harvesting closure threshold, as well as the anticipated start, end, and overall duration of closures. We illustrate the application of this framework to two Scottish aquaculture regions: One with a high spatial concentration of harvesting sites (Shetland) and one with more dispersed sites (West Scotland and the Hebrides). Through a comprehensive yearly prediction experiment, we demonstrate considerable skill in predicting the impact of unseen HAB seasons at a regional level.

The queen scallop Aequipecten opercularis: A slow domoic acid depurator?

Domoic acid (DA) is a dangerous phycotoxin produced by several strains of diatoms of the genus Pseudo-nitzschia, and responsible for Amnesic Shellfish Poisoning (ASP) in humans. The increasingly intense ASP-outbreaks along the English Channel over the last three decades have forced persistent harvest closures of economically important and highly contaminated bivalve stocks exhibiting slow DA-depuration rates, like the king scallop Pecten maximus. Under this scenario, other pectinid species, such as the queen scallop Aequipecten opercularis have been empirically proposed as alternative resources to redress the high economic losses due to the banning of the exploitation of P. maximus. Nevertheless, the kinetics of DA depuration in A. opercularis have not been assessed so far, and its direct extraction after ASP-episodes could represent a serious threat to public health. Hence, the main objective of this work was to estimate the DA-depuration rate in the digestive gland (DG) of naturally contaminated scallops A. opercularis after a toxic Pseudo-nitzschia australis bloom subjected to experimental depuration in the laboratory for 30 days. This study also intended to go further in the knowledge about the anatomical distribution of DA in scallop tissues, and corroborate the implications of autophagy in DA-sequestration in the DG of this species as recently hypothesized. In the DG, the DA-depuration rate (0.018 day−1) suggested that even with toxin burdens as low as 40 mg⋅kg−1 in the DG, queen scallops may remain contaminated for about 70 days, thus longer under intensely contamination scenarios. The subcellular analyses corroborated DA-sequestration mainly through late-autophagy within residual bodies in the DG, without differences in the frequencies of anti-DA labeled residual bodies across the entire depuration process. These results revealed that A. opercularis cannot be considered a fast DA-depurator, and represent a baseline knowledge for decision-making about harvesting natural beds of queen scallops after toxic Pseudo-nitzschia blooms. The findings of this work also represent a cornerstone for further research to accelerate DA-depuration in this species.

Red tides in the Galician rías: historical overview, ecological impact, and future monitoring strategies.

The Galician rías (NW Iberia, Spain) are coastal embayments at the northern boundary of the Canary Current upwelling system. Their favourable conditions for phytoplankton growth turn them into a suitable area for the development of aquaculture activities and a site of most of the national shellfish production. Phytoplankton blooms, a natural phenomenon inside the rías, under certain conditions eventually lead to seawater discolourations (colloquially known as "red tides"). Because of their transient nature, available records derive mainly from opportunistic samplings or casual observations, and are scattered in the literature. As a rule of thumb, red tides in the NW Iberian Peninsula are of non-toxic nature and are not systematically monitored. However, in recent years striking exceptions such as those of the toxic dinoflagellate Alexandrium minutum, a producer of paralytic shellfish toxins, have been registered. The present study goes through a historical overview of red tides in the Galician rías, describing their colouring, responsible organisms, seasonal and geographical occurrence, and their association with other features (harmful algal blooms, biotoxins and shellfish harvesting closures, bioluminescence, etc.), ending with social challenges and proposals for improving the monitoring of red tides in the future.

Women managers, local wisdom, and customary practice in marine conservation, Raja Ampat, Papua

The critical role of women in natural resource management is becoming increasingly recognized globally. In many Pacific communities, women are highly dependent on natural resources to feed and support their families, and their lives are closely entwined with the quality and quantity of these resources. However, in traditional patriarchal systems, women face multiple challenges related to traditional gender dynamics, including unequal access to natural resources, and lack of decision-making power. Sasi, a customary practice to manage the continuous supply of forest or marine resources by applying temporary harvest closures, has been practiced for more than 400 years in the eastern part of Indonesia, historically by men. In a world-first initiative, a women’s group in West Papua, Waifuna, undertook management of a sasi in 2008, with their rights fully acknowledged by the subvillage government, church, and customary holders. Here, we describe and discuss the group’s management of sea cucumbers and lobsters. We found that, despite the challenges they faced, through sasi management women increased their capacity to participate in conservation activities and decision-making, as well as contribute to marine conservation efforts. In addition, the whole community benefitted from changing perspectives on women’s abilities to manage natural resources because of the deconstruction of the prohibitive social norms that restricted women’s participation in the past.

A Survey of dinophysis spp. and their potential to cause diarrhetic shellfish poisoning in coastal waters of the United States.

Multiple species of the genus Dinophysis produce diarrhetic shellfish toxins (okadaic acid and dinophysistoxins, OA/DTXs analogues) and/or pectenotoxins (PTXs). Only since 2008 have DSP events (illnesses and/or shellfish harvesting closures) become recognized as a threat to human health in the US. This study characterized 20 strains representing five species of Dinophysis spp. isolated from three US coastal regions that have experienced DSP events - the Northeast/Mid-Atlantic, the Gulf of Mexico, and the Pacific Northwest. Using a combination of morphometric and DNA-based evidence, seven Northeast/Mid-Atlantic isolates and four Pacific Northwest isolates were classified as D. acuminata, a total of four isolates from two coasts were classified as D. norvegica, two isolates from the Pacific Northwest coast were identified as D. fortii, and three isolates from the Gulf of Mexico were identified as D. ovum and D. caudata. Toxin profiles of D. acuminata and D. norvegica varied by their geographical origin within the US. Cross-regional comparison of toxin profiles was not possible with the other three species, however within each region, distinct species-conserved profiles for isolates of D. fortii, D. ovum, and D. caudata were observed. Historical and recent data from various State and Tribal monitoring programs were compiled and compared, including maximum recorded cell abundances of Dinophysis spp., maximum concentration of OA/DTXs recorded in commercial shellfish species, and duration of harvesting closures, to provide perspective regarding potential for DSP impacts to regional public health and shellfish industry.

Using a weight of evidence approach to identify sources of microbiological contamination in a shellfish-growing area with “Restricted” classification

Shellfish-growing areas in rural catchments are occasionally affected by elevated faecal contamination from diffuse sources and may be subject to frequent harvest closures/classification downgrades. We combined traditional risk management methods based on sanitary surveys and monitoring of Escherichia coli in seawater and shellfish with faecal source tracking, bacterial source apportionment, and hydrometeorological modelling to determine the causes of elevated E. coli concentrations contributing to harvest closures in Papanui Inlet (Aotearoa New Zealand). These multiple lines of evidence were used to inform a weight of evidence assessment of bacterial contamination in the inlet. Ruminant livestock was estimated to contribute 80% of the faecal coliform loading. Concentrations of E. coli in seawater were low (≤ 87 MPN 100ml-1) whilst concentrations in tuaki/cockles/little neck clams (Austrovenus stutchburyi) occasionally exceeded the "Approved" classification limit (230 MPN 100g-1). The most frequent positive genetic markers in seawater were the seagull (Catellicoccus marimammalium) (54% of seawater samples), and in shellfish, the bovine and seagull markers (both 12.5% of shellfish samples). Solar radiation was negatively correlated with E. coli in tuaki. We found that the growing area is affected by faecal inputs from animal and, to a lesser extent, human (septic tank discharges) sources which elevate contamination to levels detectable in tuaki but not in seawater, particularly in the summer months. The innovative approach can enhance the management of shellfish-growing areas affected by intermittent contamination and enables more targeted action to reduce pollution to improve shellfish water quality.

Quantifying Spatio-temporal risk of Harmful Algal Blooms and their impacts on bivalve shellfish mariculture using a data-driven modelling approach

Harmful algal blooms (HABs) intoxicate and asphyxiate marine life, causing devastating environmental and socio-economic impacts, costing at least $8bn/yr globally. Accumulation of phycotoxins from HAB phytoplankton in filter-feeding shellfish can poison human consumers, prompting harvesting closures at shellfish production sites. To quantify long-term intoxication risk from Dinophysis HAB species, we used historical HAB monitoring data (2009–2020) to develop a new modelling approach to predict Dinophysis toxin concentrations in a range of bivalve shellfish species at shellfish sites in Western Scotland, South-West England and Northern France. A spatiotemporal statistical modelling framework was developed within the Generalized Additive Model (GAM) framework to quantify long-term HAB risks for different bivalve shellfish species across each region, capturing seasonal variations, and spatiotemporal interactions. In all regions spatial functions were most important for predicting seasonal HAB risk, offering the potential to inform optimal siting of new shellfish operations and safe harvesting periods for businesses. A 10-fold cross-validation experiment was carried out for each region, to test the models’ ability to predict toxin risk at harvesting locations for which data were withheld from the model. Performance was assessed by comparing ranked predicted and observed mean toxin levels at each site within each region: the correlation of ranks was 0.78 for Northern France, 0.64 for Western Scotland, and 0.34 for South-West England, indicating our approach has promise for predicting unknown HAB risk, depending on the region and suitability of training data.

HABs in coastal upwelling systems: Insights from an exceptional red tide of the toxigenic dinoflagellate Alexandrium minutum

Alexandrium minutum blooms generally occur in semi-enclosed sites such as estuaries, harbours and lagoons, where enhanced stratification, restricted circulation and accumulation of resting cysts in the sediment set suitable habitat conditions for the proliferation of this paralytic shellfish poisoning toxigenic species. In the Galician Rías Baixas (NW Iberian Peninsula), according to weekly time-series between 1994 and 2020, blooms of A. minutum were recurrent in small, shallow estuarine bays inside the Rías de Vigo and Pontevedra, but rarely detected, and if so at low concentrations, out of these environments. However, from May to July 2018 it developed as usual in the small inner bays but then spread over both Rías (Vigo and Pontevedra) causing discoloured waters during one month and prolonged harvesting closures. Meteorological conditions during that period (rains / runoff higher than climatological averages, sustained temperature increment and oscillating wind pattern –i.e., series of upwelling-relaxation cycles), fostered optimal circumstances for the development of that extensive and massive proliferation: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset and development inside a small inner bay; transport within the surface layer, from these sites towards the interior parts of the Ría; and dispersion all over the embayment. Seedbeds with high concentrations of resting cysts were detected several months after the bloom, which may have favoured flourishment of A. minutum in the following two years, markedly in 2020. The present work contributes to the general understanding of the dynamics of harmful algal blooms (HABs), from which surveillance indicators of the state of marine ecosystems and their evolution can be derived. We hypothesize that the intensity and frequency of A. minutum proliferations in the Galician Rías could increase under projected climate trends.

Harmful Algae and Oceanographic Conditions in the Strait of Georgia, Canada Based on Citizen Science Monitoring

In British Columbia (BC), harmful algal blooms (HABs) regularly cause severe economic losses through finfish mortalities and shellfish harvest closures due to toxin accumulation, gill damage, or hypoxia. As there is no routine governmental monitoring of HAB phenomena in BC, HAB variability, and its potential links to environmental drivers are not well understood. Here we present results from a well-managed citizen science program which collected an unprecedented 4 year, high-resolution (∼bi-monthly, ∼80 stations) dataset of harmful algae (HA) concentrations and corresponding physical and chemical properties of seawater throughout the Strait of Georgia (SoG), BC. Analysis of this dataset revealed statistically significant interannual and seasonal relationships between environmental drivers and the most common HA taxa: Rhizosolenia setigera, Dictyocha spp., Alexandrium spp., Heterosigma akashiwo, Chaetoceros convolutus, and C. concavicornis. HABs exhibited significant interannual variations; specifically, no HABs were found during the summer of 2015, blooms of Dictyocha occurred in 2016 and 2017, and dense blooms of Heterosigma and Noctiluca occurred in 2018. In addition, HA prevalence corresponded with negative effects observed in local aquaculture facilities where higher toxins concentrations (causing Paralytic and Diarrhetic Shellfish Poisonings) in shellfish flesh were detected during years with greater abundance of Alexandrium and Dinophysis. Furthermore, salmon mass mortality at fish farms corresponded to years with high concentrations of Heterosigma and Dictyocha. As such, these results highlight the need for long-term data to evaluate the potential role of HA as a stressor on the SoG ecosystem.

Determinants of Gray Wolf (<i>Canis lupus</i>) Sightings in Denali National Park

Wildlife viewing within protected areas is an increasingly popular recreational activity. Management agencies are often tasked with providing these opportunities, yet quantitative analyses of factors influencing wildlife sightings are lacking. We analyzed locations of GPS-collared wolves and wolf sightings from 2945 trips in Denali National Park and Preserve, Alaska, USA, to provide a mechanistic understanding of how viewing opportunities are influenced by attributes of wolves and physical, biological, and harvest characteristics. We found that the presence of masking vegetation, den site proximity to the road, pack size, and presence of a wolf harvest closure adjacent to the park affected wolf sightings, and the influence of den proximity on sightings depended on harvest management. Wolf sightings increased with den site proximity to the road in years with a harvest closure adjacent to the park but not in the absence of the closure. The effect of the harvest closure on sightings was similar in magnitude to an increase in pack size by two wolves or a more than a two-fold decrease in masking vegetation. These findings were consistent across a 10-fold change in spatial resolution. Quantitative analysis of the factors influencing wildlife sightings provides valuable insight for agencies tasked with managing viewing opportunities.

Distribution and Population Size of Emperor Geese during the Breeding Season on the Seward Peninsula, Alaska

The Emperor Goose (Anser canagicus) is a year-round occupant of northern latitudes, spending its entire annual cycle in coastal habitats of western Alaska and the Russian Far East. Over the last several decades, the Emperor Goose population underwent a pronounced decline, prompting 30 consecutive years of harvest closures, followed by a protracted recovery and the recent reopening of harvest. This recovery was primarily documented on the Yukon-Kuskokwim Delta in western Alaska, where an estimated 80% – 90% of the world’s Emperor Goose population breeds. However, the size and status of their population on the Seward Peninsula, Alaska, which is their only other significant breeding area in North America, remains almost completely unknown. Therefore, to better inform population and harvest management of Emperor Geese in western Alaska, we conducted extensive aerial surveys of Emperor Geese along the northern coast of the Seward Peninsula during the breeding season. During the summer of 2018, we surveyed 150 transects totaling 351 km2, for a total sampled fraction of 7.2% of the 4853 km2 survey area. Using a double-observer technique that accounted for detection probability, we estimated a population of 1226 (95% CI: 792 – 1660) Emperor Geese on the Seward Peninsula, of which 614 (95% CI: 416 – 811) were considered breeding birds based on their observed status as singles or pairs. Most Emperor Geese (61%) were found on barrier islands, even though these islands accounted for just 3.5% of the total survey area; the remaining geese were found in lowland coastal habitats (23%) or upland tundra (16%). Overall, our surveys indicate a small breeding population of Emperor Geese on the Seward Peninsula, which raises some conservation concern. Further reductions or extinction of this small population would leave Emperor Geese with only one significant breeding area in North America. Because Emperor Geese typically display high breeding site fidelity and female natal philopatry, any future growth of this small population will likely to need to come from within.

Thin layers of phytoplankton and harmful algae events in a coastal upwelling system

We combined time-series from a monitoring program and specific field observations in order to: 1) describe the characteristics of thin layers of phytoplankton (TLP) in the Galician Rías Baixas (NW Iberian Peninsula), 2) investigate the relationship between spatially-extended TLP (se-TLP) events and environmental variables, and 3) analyze the relationship between TLP occurrence and cell densities of toxin-producing harmful algal bloom (THAB) species. Between 2012 and 2015, a total of 118 TLP were detected in any of the 39 stations weekly sampled in the study area in the frame of the monitoring program, which represents a frequency of occurrence of 2%. Most TLP (84%) were detected between May-August and located slightly below shallow pycnoclines. Eight se-TLP events, i.e., when at least five stations were simultaneously influenced by the occurrence of a TLP, were identified during the period 2012–2015. Six out eight of these events happened during summer-upwelling conditions, and according to a Principal Component Analysis (PCA) they were positively correlated with thermal stratification. The other two events, detected during spring-downwelling, were positively correlated with haline stratification. A logistic regression model including six variables (surface temperature, relative humidity, bottom salinity, a proxy for the intrusion of the Miño River plume into Ría de Vigo, Miño River flow, and bottom temperature) explained 42% of the variance in the occurrence of se-TLP events. The temporal persistence of TLP events was confirmed by observations carried out during specific cruises, which showed how TLP were formed and disappeared over short periods of time in response to changes in vertical mixing. TLP were more frequently observed in Ría de Pontevedra, which was characterized by longer harvesting closures due to detection of Dinophysis toxins (DSP: diarrhetic shellfish poisoning toxins and pectenotoxins) above regulatory levels. About 25% of the TLP detected in the Rías Baixas were associated with increased cell densities of potentially toxic Pseudo-nitzschia species (ASP: amnesic shellfish poisoning) and of D. acuminata. These results suggest that a relationship may be established between the occurrence of TLP and the growth and/or accumulation of the main THAB species in the Galician Rías Baixas.

Dihydrodinophysistoxin-1 Produced by Dinophysis norvegica in the Gulf of Maine, USA and Its Accumulation in Shellfish.

Dihydrodinophysistoxin-1 (dihydro-DTX1, (M-H)− m/z 819.5), described previously from a marine sponge but never identified as to its biological source or described in shellfish, was detected in multiple species of commercial shellfish collected from the central coast of the Gulf of Maine, USA in 2016 and in 2018 during blooms of the dinoflagellate Dinophysis norvegica. Toxin screening by protein phosphatase inhibition (PPIA) first detected the presence of diarrhetic shellfish poisoning-like bioactivity; however, confirmatory analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) failed to detect okadaic acid (OA, (M-H)− m/z 803.5), dinophysistoxin-1 (DTX1, (M-H)− m/z 817.5), or dinophysistoxin-2 (DTX2, (M-H)− m/z 803.5) in samples collected during the bloom. Bioactivity-guided fractionation followed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) tentatively identified dihydro-DTX1 in the PPIA active fraction. LC-MS/MS measurements showed an absence of OA, DTX1, and DTX2, but confirmed the presence of dihydro-DTX1 in shellfish during blooms of D. norvegica in both years, with results correlating well with PPIA testing. Two laboratory cultures of D. norvegica isolated from the 2018 bloom were found to produce dihydro-DTX1 as the sole DSP toxin, confirming the source of this compound in shellfish. Estimated concentrations of dihydro-DTX1 were >0.16 ppm in multiple shellfish species (max. 1.1 ppm) during the blooms in 2016 and 2018. Assuming an equivalent potency and molar response to DTX1, the authority initiated precautionary shellfish harvesting closures in both years. To date, no illnesses have been associated with the presence of dihydro-DTX1 in shellfish in the Gulf of Maine region and studies are underway to determine the potency of this new toxin relative to the currently regulated DSP toxins in order to develop appropriate management guidance.

The Effect of a Spatial Harvest Closure Area on the Abundance, Movement, and Demographics of an Intensively Fished Population of Dungeness Crabs (Cancer magister) Along Roberts Bank, British Columbia, Canada

In addition to regulating sex, size, and season of harvest, resource managers can implement spatial fishery closures as a management tool to protect Dungeness crab populations. Yet, we have little understanding of the role that spatial closures play in conserving crab populations, especially in fisheries management zones that are subject to intensive harvest. The primary purpose of this study was to evaluate the biological effectiveness of a crab closure area adjacent to an intensive fishery, by examining relative abundance, population demographics, and seasonal movement patterns within and outside of a closure area. Relative abundance and population demographics were assessed weekly from August to October, using standardized trap lines distributed at four locations, stratified by treatment (inside versus outside of closure area) and water depth. To obtain individual male crab movement data within and outside of the closure area, mobile acoustic tracking surveys were conducted one to three times per week in the autumn and winter. Male crabs were larger and in greater abundance inside the closure area than outside. The overall trend in male crab movement was southwest towards deeper water during autumn and winter. Our research supports the hypothesis that fisheries decrease the abundance and size of an exploited species, but closure areas may reduce these effects. Based on the observed seasonal movement patterns of crabs, it appeared that the closure area provided a temporary refuge from harvest. Resource managers should consider seasonal movement patterns, habitat use, and quality of available habitat when selecting closure area boundaries.

Domoic acid depuration by intertidal bivalves fed on toxin-producing Pseudo-nitzschia multiseries.

Domoic acid (DA), a neurotoxin produced by certain species within the diatom genus Pseudo-nitzschia, has caused numerous persistent harvest closures for razor clam Siliqua patula along the outer coast of Washington State (USA) over the last three decades. In comparison, bivalve harvest closures for DA have only occurred three times in Washington's largest inland estuary, Puget Sound, which has a variety of bivalve species excluding razor clam. While differing bloom dynamics in the two locations are responsible for much of the disparity in shellfish harvest closures, species-specific differences in DA depuration may affect the duration of harvest closures in the two regions. Toxin-producing Pseudo-nitzschia multiseries were fed to four species of bivalves, followed by measurement of tissue DA content over time to estimate depuration rate. Experimental species include razor clam and three species of intertidal Puget Sound bivalves: soft-shell clam Mya arenaria, purple varnish clam Nuttallia obscurata and Manila clam Ruditapes philippinarum. Using an exponential decay model, DA depuration rates were estimated as: 0.02·day−1 ±0.08 for razor clam, 0.10·day−1 ±0.07 for purple varnish clam, 0.37·day−1 ±0.03 for soft-shell clam, and 0.44·day−1 ±0.02 for Manila clam. Puget Sound species depurated DA between five and 22 times as fast as outer coast razor clam. Within Puget Sound species, slow DA depuration rates in purple varnish clam indicate that it may be a good sentinel organism for assessing beach-wide maximum DA concentrations in Puget Sound bivalves.

Can offshore HABs hinder the development of offshore mussel aquaculture in the northeast United States?

Shellfish aquaculture is predicted to expand from nearshore locations into US federal waters in response to increased seafood demand and domestic food security concerns. As the industry moves into new areas, risk from offshore harmful algal blooms (HABs) focuses attention on new needs for summary background information about past algal bloom events to guide management decisions and monitoring programs. Indigenous Alexandrium and Pseudo-nitzschia species both have triggered shellfish harvest closures in offshore areas of New England after toxins were measured in bivalve tissues. The information in this short communication summarizes the scope of monitoring and management programs for HABs and their toxins in offshore New England areas where future aquaculture may be located. It also identifies HAB-related challenges to offshore farming development and suggests future research and monitoring directions.

Lipophilic Toxins in Galicia (NW Spain) between 2014 and 2017: Incidence on the Main Molluscan Species and Analysis of the Monitoring Efficiency.

Galicia is an area with a strong mussel aquaculture industry in addition to other important bivalve mollusc fisheries. Between 2014 and 2017, 18,862 samples were analyzed for EU regulated marine lipophilic toxins. Okadaic acid (OA) was the most prevalent toxin and the only single toxin that produced harvesting closures. Toxin concentrations in raft mussels were generally higher than those recorded in other bivalves, justifying the use of this species as an indicator. The Rías of Pontevedra and Muros were the ones most affected by OA and DTX2 and the Ría of Ares by YTXs. In general, the outer areas of the Rías were more affected by OA and DTX2 than the inner ones. The OA level reached a maximum in spring, while DTX2 was almost entirely restricted to the fall–winter season. YTXs peaked in August–September. The toxins of the OA group were nearly completely esterified in all the bivalves studied except mussels and queen scallops. Risk of intoxication with the current monitoring system is low. In less than 2% of cases did the first detection of OA in an area exceed the regulatory limit. In no case, could any effect on humans be expected. The apparent intoxication and depuration rates were similar and directly related, suggesting that the rates are regulated mainly by oceanographic characteristics.

Pseudo-nitzschia Blooms in a Coastal Upwelling System: Remote Sensing Detection, Toxicity and Environmental Variables

The NW coast of the Iberian Peninsula is dominated by extensive shellfish farming, which places this region as a world leader in mussel production. Harmful algal blooms in the area frequent lead to lengthy harvesting closures threatening food security. This study developed a framework for the detection of Pseudo-nitzschia blooms in the Galician rias from satellite data (MERIS full-resolution images) and identified key variables that affect their abundance and toxicity. Two events of toxin-containing Pseudo-nitzschia were detected (up to 2.5 μg L−1 pDA) in the area. This study suggests that even moderate densities of Pseudo-nitzschia in this area might indicate high toxin content. Empirical models for particulate domoic acid (pDA) were developed based on MERIS FR data. The resulting remote-sensing model, including MERIS bands centered around 510, 560, and 620 nm explain 73% of the pDA variance (R2 = 0.73, p < 0.001). The results show that higher salinity values and lower Si(OH)4/N ratios favour higher Pseudo-nitzschia spp. abundances. High pDA values seem to be associated with relatively high PO43, low NO3− concentrations, and low Si(OH)4/N. While MERIS FR data and regionally specific algorithms can be useful for detecting Pseudo-nitzschia blooms, nutrient relationships are crucial for predicting the toxicity of these blooms.

Modeling temporal closures in a multispecies recreational fishery reveals tradeoffs associated with species seasonality and angler effort dynamics

Seasonal closures are commonly used to reduce fishing mortality in recreational and commercial fisheries, but they may be less effective when effort is merely displaced to the open season or in multispecies fisheries that allow for discarding to continue while other species are targeted. The latter is especially true for the valuable multispecies recreational reef fish fishery in the Gulf of Mexico, where discard mortality is high and it can be difficult to avoid catching one species while fishing for others. We evaluated the utility of complete bottom fishing closures (in addition to already mandated harvest closures) that would temporarily prohibit recreational reef fishing as a means to control effort, reduce the amount of dead discards, and improve stock status of multiple species. In this study we developed age-structured population models for six Gulf of Mexico reef fish species that dominate the recreational catch, with each model linked to a monthly effort dynamic model for the recreational fishery. The effect of closing any given month(s) varied across species and resulted in tradeoffs, such that some closures may result in positive effects on biomass of one species and negative effects on others. For example, a spring closure was predicted to have positive effects on Red Snapper Lutjanus campechanus spawning stock biomass but negative effects on Gag grouper Mycteroperca microlepis due to the contrasting patterns in harvest rates during those months. These tradeoffs were associated with seasonal availability patterns and the degree to which anglers might shift effort to the open season. The closure scenarios that were most likely to reduce dead discards without negatively impacting harvest, spawning biomass, or total effort occurred in late winter and early spring (March & April). In evaluating seasonal fishing closures, the gains in biomass and reductions in dead discards must be weighed against the socio-economic tradeoffs, in terms of lost effort-generated revenue at various spatial and temporal scales and angler dissatisfaction.

Factors that predict deep inferior epigastric perforator flap donor site hernia and bulge

Deep inferior epigastric artery perforator (DIEP) flap has become the gold standard in autologous breast reconstruction. Attention is now being focused on the impact of DIEP flap harvest technique on abdominal hernia rates. The aim of this study was to evaluate DIEP abdominal wall morbidity in relation to flap harvest and fascial closure technique. A retrospective analysis of patients undergoing DIEP flap breast reconstruction between 2012 and 2016 was performed. Post-operative evaluation of the abdominal wall integrity was performed by an operating consultant. The rectus fascia was closed using one of three techniques. The study included 202 patients, in whom 234 DIEP flaps were performed. Eight patients (3.4%) developed a clinically evident abdominal bulge post-operatively and one (0.5%) had a hernia. Harvesting two or more perforators was more likely to result in post-operative abdominal hernia/bulge than taking a single perforator (p = .032). Using a perforator from the lateral row or both rows was more likely to result in a hernia/bulge than if a single medial perforator was harvested (p = .026). Comparison of the rectus fascia closure technique did not show any statistically significant difference in abdominal wall morbidity. Consideration should be given towards perforator selection when harvesting a DIEP flap. Where appropriate, a suitable single medial row perforator with a favourable suprafascial course should be chosen. This study has not shown mesh-free fascial closure to be inferior to mesh-supported closure. Careful consideration to the role of synthetic mesh within this patient cohort should be given.