Aitor Laza - Academia.edu (original) (raw)

Papers by Aitor Laza

Environmental Microbiology, 2021

In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated wit... more In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio-temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulations to: i) establish the current colonization of the species in the Bay of Biscay, ii) assess the spatial connectivity among sampling zones that explain this distribution, iii) identify sentinel zones to monitor future expansion. Throughout a sampling campaign carried out in August-September 2018, microscope analysis showed that the species develops in the south-east of the bay where optimal temperatures foster blooms. Quantitative PCR analyses revealed its presence across almost the whole bay to the western English Channel. An eDNA time-series collected on plastic samplers showed that the species occurs in the bay from April to September. Due to the water circulation, colonization of the whole bay from the southern blooming zones is explained by inter-site connectivity. Key areas in the middle of the bay permit continuous dispersal connectivity towards the north. These key areas are proposed as sentinel zones to monitor O. cf. siamensis invasions towards the presumably warming water of the North-East Atlantic. This article is protected by copyright. All rights reserved.

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.

Aquatic Microbial Ecology, 2015

Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from th... more Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from the Teleaulax/Plagioselmis/Geminigera group via their ciliate prey Mesodinium rubrum, but other cryptophyte and algal sources have occasionally been found. Identifying the specific prey of ciliates fed upon by mixotrophic Dinophysis species is a requisite to improve predictive capabilities of their bloom formation. Here we examined the origin of Dinophysis plastids from Galician waters and their transfer in cross-feeding experiments in the laboratory. Plastid 23S rDNA sequences were obtained from 60 Dinophysis specimens from the Galician Rías Baixas and shelf waters. Most sequences in Dinophysis cells were identical to Teleaulax amphioxeia. Galician shelf samples also yielded T. amphioxeia-type sequences, although one of these was closer to a freshwater cryptophyte, and a few others were related with other taxa (diatoms, red algae and proteobacteria). Mesodinium cf. major, an alternative prey to M. rubrum, was identified. Crossfeeding tests in the laboratory showed that T. amphioxeia, T. minuta, T. gracilis, and Plagioselmis prolonga sustained growth of M. rubrum. D. acuminata cultivated on a M. rubrum-T. amphioxeia system was transferred to M. rubrum fed upon T. minuta, T. gracilis and P. prolonga. After > 2 mo of acclimation, T. amphioxeia plastid 23S rDNA and psbA gene sequences from D. acuminata were replaced by those of secondary cryptophytes. Here we confirm 2 cryptophytes, T. minuta and P. prolonga, as suitable prey for M. rubrum. Nevertheless, field and laboratory results show that, at least for D. acuminata, T. amphioxeia represents the main source of plastids.

European journal of phycology, 2011

The morphological and genetic structure of Western Mediterranean trout Salmo cettii inhabiting ba... more The morphological and genetic structure of Western Mediterranean trout Salmo cettii inhabiting basins in Sardinia was completed to assist the design of its conservation programmes. Genetic analysis of protein-coding LDH-C1 plus sequencing mitochondrial control region gene and analyses of morphological characters described 253 specimens from seven localities in two basins in Southwest Sardinia. Nuclear and mitochondrial analyses revealed all of the fish were pure-bred native S. cettii, with no introgression from allochthonous S. trutta. The novel 18 mtDNA control region haplotypes were clustered in an 'insular' clade, strictly related to the Adriatic haplogroup, and depicted a radial network around two ancestral haplotypes. Completion of discriminant analysis using data on body pigmentation and quantitative morphologic parameters revealed three phenotypic groups within the fish. Each population and phenotype, characterised by high values of nucleotide and haplotype diversity, were not genetically differentiated and not geographically structured according to the two hydrological basins. Geometric morphometric analysis, based on 15 landmarkers, revealed pronounced and highly significant differences in body shape morphology between populations, suggesting S. cettii is locally adapting to extreme environmental conditions and so future management plans for these populations should treat the two basins as distinct morphological units.

Regional Studies in Marine Science

Frontiers in Marine Science

European Journal of Phycology

European Journal of Phycology

Munibe Ciencias Naturales

Environmental Science & Technology

FEMS microbiology ecology, 2018

The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a ... more The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a cosmopolitan distribution. This study explored if strains from different environments and different morphotypes, isolated from three locations in the Atlantic Iberian Peninsula and two from the Mediterranean Sea, showed different responses to varying light regimes, after confirming that all strains belonged to the same ribotype. Growth rates and photosynthetic parameters such as Fo, Fv/Fm, and rETRmax were analysed with a Coulter counter, a water-PAM and a fast repetition rate fluorometer. The photosynthetic properties were investigated in a high light stress experiment using strains acclimated to low light (LL) and high light (HL). The highest growth rate was 0.23 day-1 at 80 and 100 μmol photons m-2 s-1 for strains Dn150EHU and Dn60EHU, originated from different locations. Under control conditions (18°C and 90 μmol photons m-2 s-1), growth rate was on average 0.10 day-1. The HL stress ...

Regional Studies in Marine Science

Environmental Microbiology, 2021

In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated wit... more In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio-temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulations to: i) establish the current colonization of the species in the Bay of Biscay, ii) assess the spatial connectivity among sampling zones that explain this distribution, iii) identify sentinel zones to monitor future expansion. Throughout a sampling campaign carried out in August-September 2018, microscope analysis showed that the species develops in the south-east of the bay where optimal temperatures foster blooms. Quantitative PCR analyses revealed its presence across almost the whole bay to the western English Channel. An eDNA time-series collected on plastic samplers showed that the species occurs in the bay from April to September. Due to the water circulation, colonization of the whole bay from the southern blooming zones is explained by inter-site connectivity. Key areas in the middle of the bay permit continuous dispersal connectivity towards the north. These key areas are proposed as sentinel zones to monitor O. cf. siamensis invasions towards the presumably warming water of the North-East Atlantic. This article is protected by copyright. All rights reserved.

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.

Aquatic Microbial Ecology, 2015

Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from th... more Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from the Teleaulax/Plagioselmis/Geminigera group via their ciliate prey Mesodinium rubrum, but other cryptophyte and algal sources have occasionally been found. Identifying the specific prey of ciliates fed upon by mixotrophic Dinophysis species is a requisite to improve predictive capabilities of their bloom formation. Here we examined the origin of Dinophysis plastids from Galician waters and their transfer in cross-feeding experiments in the laboratory. Plastid 23S rDNA sequences were obtained from 60 Dinophysis specimens from the Galician Rías Baixas and shelf waters. Most sequences in Dinophysis cells were identical to Teleaulax amphioxeia. Galician shelf samples also yielded T. amphioxeia-type sequences, although one of these was closer to a freshwater cryptophyte, and a few others were related with other taxa (diatoms, red algae and proteobacteria). Mesodinium cf. major, an alternative prey to M. rubrum, was identified. Crossfeeding tests in the laboratory showed that T. amphioxeia, T. minuta, T. gracilis, and Plagioselmis prolonga sustained growth of M. rubrum. D. acuminata cultivated on a M. rubrum-T. amphioxeia system was transferred to M. rubrum fed upon T. minuta, T. gracilis and P. prolonga. After > 2 mo of acclimation, T. amphioxeia plastid 23S rDNA and psbA gene sequences from D. acuminata were replaced by those of secondary cryptophytes. Here we confirm 2 cryptophytes, T. minuta and P. prolonga, as suitable prey for M. rubrum. Nevertheless, field and laboratory results show that, at least for D. acuminata, T. amphioxeia represents the main source of plastids.

European journal of phycology, 2011

The morphological and genetic structure of Western Mediterranean trout Salmo cettii inhabiting ba... more The morphological and genetic structure of Western Mediterranean trout Salmo cettii inhabiting basins in Sardinia was completed to assist the design of its conservation programmes. Genetic analysis of protein-coding LDH-C1 plus sequencing mitochondrial control region gene and analyses of morphological characters described 253 specimens from seven localities in two basins in Southwest Sardinia. Nuclear and mitochondrial analyses revealed all of the fish were pure-bred native S. cettii, with no introgression from allochthonous S. trutta. The novel 18 mtDNA control region haplotypes were clustered in an 'insular' clade, strictly related to the Adriatic haplogroup, and depicted a radial network around two ancestral haplotypes. Completion of discriminant analysis using data on body pigmentation and quantitative morphologic parameters revealed three phenotypic groups within the fish. Each population and phenotype, characterised by high values of nucleotide and haplotype diversity, were not genetically differentiated and not geographically structured according to the two hydrological basins. Geometric morphometric analysis, based on 15 landmarkers, revealed pronounced and highly significant differences in body shape morphology between populations, suggesting S. cettii is locally adapting to extreme environmental conditions and so future management plans for these populations should treat the two basins as distinct morphological units.

Regional Studies in Marine Science

Frontiers in Marine Science

European Journal of Phycology

European Journal of Phycology

Munibe Ciencias Naturales

Environmental Science & Technology

FEMS microbiology ecology, 2018

The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a ... more The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a cosmopolitan distribution. This study explored if strains from different environments and different morphotypes, isolated from three locations in the Atlantic Iberian Peninsula and two from the Mediterranean Sea, showed different responses to varying light regimes, after confirming that all strains belonged to the same ribotype. Growth rates and photosynthetic parameters such as Fo, Fv/Fm, and rETRmax were analysed with a Coulter counter, a water-PAM and a fast repetition rate fluorometer. The photosynthetic properties were investigated in a high light stress experiment using strains acclimated to low light (LL) and high light (HL). The highest growth rate was 0.23 day-1 at 80 and 100 μmol photons m-2 s-1 for strains Dn150EHU and Dn60EHU, originated from different locations. Under control conditions (18°C and 90 μmol photons m-2 s-1), growth rate was on average 0.10 day-1. The HL stress ...

Regional Studies in Marine Science