Bravo, I. (Isabel)

Díaz, P.A. (Patricio Andrés)

Fraga, S. (Santiago)

Reguera, B. (Beatriz)

Ruiz-Villarreal, M. (Manuel)

English

Repositorio Institucional Digital del IEO

ICES  CM  2014/H:25  Conditions  associated  with  unusual  summer  blooms  of  Dinophysis  acuta  in  an  upwelling  area    Patricio  A.  Díaz  (1),  Beatriz  Reguera  (1),  Isabel  Bravo  (1),  Manuel  Ruiz-­‐‑Villarreal  (2),  Santiago  Fraga  (1)  (1)  Instituto  Español  de  Oceanografía,  Centro  Oceanografico  de  Vigo,  Vigo,  Spain;  (2)  Instituto  Español  de  Oceanografía,  Centro  Oceanografico  de  A  Coruña,  A  Coruña,  Spain.  Presenter  contact  details:  patricio.diaz@vi.ieo.es,  Phone  +34  986  492  111    Summary  Dinophysis   acuta   is   an   important   producer   of   diarrhetic   shellfish   poisoning   (DSP)   toxins   and  pectenotoxins  in  European  Atlantic  coastal  waters.  Blooms  (>  103  cell  l-­‐‑1)  of  this  species  in  the  Galician  Rías  Baixas  (NW  Spain)  are  very  seasonal  (early  autumn).  They  have  been  associated  with  alongshore  transport,  at  the  end  of  the  upwelling  season,  of  a  population  with  its  “centre  of  gravity”  100  nm  south  (off   Aveiro,   Portugal).   Exceptional   blooms   of  D.   acuta   developed   in   situ   in   August   1989   and   1990  under  moderate  upwelling  and  stratification,  following  a  temporal  pattern  that  has  not  been  observed  since.   A   second   “normal”   bloom   occurred   at   the   end   of   the   upwelling   season   co-­‐‑occurring  with   a  paralytic   shellfish   poisoning   (PSP)   outbreak   of   Gymnodinium   catenatum.   One   objective   of   the   EU  ASIMUTH   project   was   “identification   of   key   past   events   which   will   be   re-­‐‑analysed   and   used   for  training   the   modelling   system”.   Here   we   re-­‐‑analyze   oceanographic   data   from   cross-­‐‑shelf   transects  sampled  during  3  mini-­‐‑cruises  on  September  13,  27  and  October  11,  1990,  before,  during  and  after  the  autumn  transition,  and  from  weekly  monitoring  in  Ría  de  Vigo  and  Ría  de  Pontevedra.  Our  objective  was   to   parameterize   shelf   conditions   associated   with   the   onset,   development   and   decline   of   this  exceptional  summer  bloom  of  D.  acuta.    Introduction  Several   species   of   the   genus  Dinophysis  are   known  producer   of   diarrhetic   shellfish  poisoning   (DSP)  toxins   and   pectenotoxins   leading   to   lengthy   shellfish   harvesting   bans   in   European   Atlantic   coastal  waters  (Van  Egmond  et  al.  1993).  These  harmful  events  are  especially  damaging  in  the  Galician  Rías  (NW  Spain)  where   they  represent   the  main  threat   for   the  mussel  aquaculture   industry  (Blanco  et  al.  2013).  Dinophysis   acuminata   Claperède  &   Lachmann   and  D.   acuta   Ehrenberg   are   the  main   agents   of  DSP  outbreaks  (Reguera  et  al.  2014)  in  Western  Iberia  coastal  waters.  The  former  occurs  through  the  whole   upwelling   season   (spring   to   early   autumn),   but   blooms   of   the   latter   are   very   seasonal   (early  autumn).  Two  different  mechanisms  have  been  proposed  to  explain  blooms  of  D.  acuta  in  the  Galician  Rías   Baixas:   i)   in   situ   growth   favoured   by   moderate   upwelling   conditions   and   strong   thermal  stratification   during   exceptionally   hot   and   dry   summers   (Reguera   et   al.   1995)   and   ii)   physical  transport   observed   during   downwelling   conditions   after   the   autumn   transition   resulting   from   a  combination  of    poleward  longshore  and  cross-­‐‑shelf  transports  (Sordo  et  al.  2001;  Escalera  et  al.  2010).  Here   we   re-­‐‑analyse   oceanographic   data   from   shelf   transects   sampled   during   3  mini-­‐‑cruises   in   late  summer   and   early   autumn   1990   and   from   weekly   monitoring   data   from   Ría   de   Vigo   and   Ría   de  Pontevedra,   to   identify   and   parameterize   environmental   conditions   that   may   have   triggered   the  exceptional  bloom  of  D.  acuta  in  1990.    Material  and  Methods  The  survey  was  carried  out  on  board  R.V.  Francisco  de  Paula  Navarro  during  three  one-­‐‑day  cruises  over  shelf   transects,   which   took   place   on   September   13,   27   and   October   11,   1990.   Water   samples   for  phytoplankton   counts  were   collected  with  Niskin   bottles.   Vertical   profiles   of   temperature,   salinity,  and  pressure  were  obtained  with  a  SeaBird  SBE-­‐‑19  CTD.   In  addition,  Sippican  XBTs  were   launched  along  a  diagonal   transect   from  Ría  de  Vigo   to   its  adjacent   shelf.  Weekly  samples   for  phytoplankton  counts   within   the  monitoring   programme  were   collected  with   a   dividable   (0-­‐‑5,   5-­‐‑10,   10-­‐‑15m)   hose  sampler  at   two  stations   located  in  Ría  de  Vigo  and  Ría  de  Pontevedra.  Upwelling   indexes  every  6  h  were  obtained  from  the  Spanish   Institute  of  Oceanography  (www.indicedeafloramiento.ieo.es).  Data  analysis  and  representation  were  performed  using  the  statistical  and  programming  software  R  2.1.12.    Results  and  Discussion  During   the   first   cruise   (13   Sept.)   there  was   an   offshore   Ekman   transport  generated   by   northerly  winds.   From   20  to   30  September   there  was  a  wind   shift  and   southerlies   became   predominant  resulting   in   onshore   Ekman   transport  and   a   significant   increase   of  temperature   with   maximum   values  close   to   19°C   at   surface   (Figure   1).  Results   from   the  second  mini-­‐‑cruise   (27  September)   strong   thermal   gradients  were   associated  with   a   dense   bloom   of  D.   acuta.   Maximum   cell   densities  (5.4x104      cells  l-­‐‑1)  were  found  at  20m  on  a   shelf   station   off   Ría   de   Vigo.   Dense  blooms  of  D.  acuta  have  been  described  to   result   from   a   combination   of  stratification   and   physical   advection   by  local   winds   patterns   (Reguera   et   al.  2012).  Our  results  suggest  that  persistent  thermal   stratification   combined   with  moderate   upwelling   during   mid-­‐‑late  summer   1990   in   the   Galician   shelf  created   the   conditions   for   unusual  summer   blooms   of   D.   acuta.   Bloom  erosion   was   associated   with   the   shift  from   southerly   to   northerly   winds   (from   1   October),   a   common   mechanism   for   dissipation   of  physically-­‐‑induced  autumn  blooms   in   the   Iberian  upwelling   system  resulting   in  an  offshore  Ekman  transport  with  maximum  values  2000  m3  s-­‐‑1  km-­‐‑1  on  7  October.    References  Blanco,  J.,  Correa,  J.,  Muñíz,  S.,  Mariño,  C.,  Martín,  H.,  Arévalo,  F.,  2013.  Evaluación  del  impacto  de  los  métodos  y  niveles  utilizados  para  el  control  de  toxinas  en  el  mejillón.  Revista  Galega  dos  Recursos  Mariños  3,  1-­‐‑55.  Escalera,  L.,  Reguera,  B.,  Moita,  T.,  Pazos,  Y.,  Cerejo,  M.,  Cabanas,  J.M.,  Ruiz-­‐‑Villarreal,  M.,  2010.  Bloom  dynamics  of  Dinophysis  acuta  in  an  upwelling  system:  In  situ  growth  versus  transport.  Hamrful  Algae  9,  312-­‐‑322.  Reguera,   B.,   Bravo,   I.,   Fraga,   S.,   1995.  Autoecology   and   some   life   history   stages   of  Dinophysis   acuta   Ehrenberg.  Journal  of  Plankton  Research  17(5),  999-­‐‑1015.  Reguera,  B.,  Velo-­‐‑Suárez,  L.,  Raine,  R.,  Park,  M.,  2012.  Harmful  Dinophysis  species:  A  review.  Harmful  Algae  14,  87-­‐‑106.  Reguera,   B.,   Riobó,   P.,   Rodríguez,   F.,   Díaz,   P.A.,   Pizarro,   G.,   Paz,   B.,   Franco,   J.M.,   Blanco,   J.,   2014.  Dinophysis  toxins:  causative  organisms,  distribution  and  fate  in  shellfish.  Marine  Drugs  12,  394-­‐‑461.  Sordo,   I.,   Barton,   E.D.,   Cotos,   J.M.,   Pazos,   Y.,   2001.   An   inshore   poleward   current   in   the   NW   of   the   Iberian  Peninsula  detected  form  satellite  images,  and  its  relation  with  G.  catenatum  and  D.  acuminata  blooms  in  the  Galician  Rias.  Estuarine,  Coastal  and  Shelf  Science  53,  787-­‐‑799.  Van   Egmond,  H.P.,  Aune,   T.,   Lassus,   P.,   Speijers,  G.J.A.,  Waldock,  M.,   1993.   Paralytic   and  diarrhoeic   shellfish  poisons:  Occurrence  in  Europe,  toxicity,  analysis  and  regulation.  Journal  of  Natural  Toxins  2,  41-­‐‑82.  Figure   1.   Time   series   of   upwelling   index   (upper),   temperature  and  D.  acuta  cell  densities  (middle)  recorded  from  4  September  to  31  October  at  Ría  de  Vigo  station.  Vertical  profiles  of  salinity,  temperature   and   D.   acuta   (lower)   during   the   three   one-­‐‑day  cruises  at  a  shelf  station.  

Conditions associated with unusual summer blooms of Dinophysis acuta in an upwelling area

Conditions  associated  with  unusual  summer  blooms  of  	Dinophysis  acuta  in  an  upwelling  area	Patricio  A.  Díaz1,  Beatriz  Reguera1,  Isabel  Bravo1,    Manuel  Ruiz-­‐‑Villarreal2,  Santiago  Fraga1	1Instituto  Español  de  Oceanografía,  Centro  Oceanográﬁco  de  Vigo,  Vigo,  Spain	2Instituto  Español  de  Oceanografía,  Centro  Oceanográﬁco  de  A  Coruña,  A  Coruña,  Spain	Increased  predictive   capabilities  of   toxic  microalgae  outbreaks   is   a  major  objective  of  harmful   algae   experts  from  any  region  subject  to  their  detrimental  eﬀects  on  aquaculture  exploitations.  In  this  context,  one  objective  of   the  EU  ASIMUTH  project  was   “identiﬁcation  of   key  past   events  which  will   be   re-­‐‑analysed  and  used   for  training   the  modelling   system”.  Here  we   re-­‐‑analyze   oceanographic  data   from   cross-­‐‑shelf   transects   sampled  during   3   mini-­‐‑cruises   on   September   13,   27   and   October   11,   1990,   before,   during   and   after   the   autumn  transition,   and   from   weekly   monitoring   in   Ría   de   Vigo   and   Ría   de   Pontevedra.   Our   objective   was   to  parameterize  shelf  conditions  associated  with  the  onset,  development  and  decline  of     an  exceptional  summer  bloom  of  D.  acuta  occurring  in  late  summer  1990.	Fig.   1.   The   study   area   in   the  Galician   Rías   Baixas   (NW  Spain)   and   shelf   stations  visited  during  the  cruises.  	ICES  CM  2014/H:25	Presenter  contact  details:  patricio.diaz@vi.ieo.es,  Phone  +34  986  492  111 Dinophysis   acuta   is   an   important   producer   of  diarrhetic   shellﬁsh  poisoning   (DSP)   toxins  and  pectenotoxins,   which   cause   lengthy   shellﬁsh  harvesting   bans   in   European   Atlantic   coastal  waters  (Van  Egmond  et  al.  1993).  These  shellﬁsh  closures   are   especially   damaging   in   the  Galician  Rías  (NW  Spain),  site  of  intense  mussel  aquaculture  with  an  annual  production  of  up  to  300,000  t  (Blanco  et  al.  2013).  Usually,  blooms  (>  103  cell  l-­‐‑1)  of  D.  acutain  the  Galician  Rías  Baixas  are  very  seasonal   (early  autumn),  appearing  at  the  end  of  the  upwelling  season.  	Introduction	Material  &  Methods	Results  and  Discussion	The   survey   was   carried   out   on   board   R.V.  Navarro  during  three  one-­‐‑day  cruises  over  shelf  transects,  which  took  place  on  September  13,  27  and   October   11,   1990.   Water   samples   for  phytoplankton   counts   were   collected   with  Niskin  boiles.  Vertical  proﬁles  of   temperature,  salinity,   and   pressure   were   obtained   with   a  SeaBird   SBE-­‐‑19   CTD.   In   addition,   Sippican  XBTs  were   launched   along   a   diagonal   transect  from  Ría   de  Vigo   to   its   adjacent   shelf.  Weekly  samples   for   phytoplankton   counts   within   the  monitoring   programme   were   collected   at   two  stations   located   in   Ría   de   Vigo   and   Ría   de  Pontevedra.  	References	 Acknowledgments	Blanco,   J.,  Correa,   J.,  Muñíz,   S.,  Mariño,  C.,  Martín,  H.,  Arévalo,  F.,   2013.  Evaluación  del  impacto  de  los  métodos  y  niveles  utilizados  para  el  control  de  toxinas  en  el  mejillón.  Revista  Galega  dos  Recursos  Mariños  3,  1-­‐‑55.	Van  Egmond,  H.P.,  Aune,  T.,  Lassus,  P.,  Speijers,  G.J.A.,  Waldock,  M.,  1993.  Paralytic  and  diarrhoeic   shellﬁsh   	 poisons:      Occurrence   in   Europe,   toxicity,   analysis   and  regulation.  Journal  of  Natural  Toxins  2,  41-­‐‑82.	Funded  by  project  Applied  Simulations  and  Integrated  Modelling  for   the  Understanding  of   Toxic   and   Harmful   algal   blooms   (ASIMUTH)   from   the   7th   Framework   Programme  (ASIMUTH/  SPACE-­‐‑Grant  Agreement  261860)  of  the  European  Commission.  	Patricio   A.   Díaz   is   supported   by   a   PhD   student   fellowship   from   the   BECAS–CHILE  Programme   of   the   National   Commission   for   Scientiﬁc   and   Technological   Research  (CONICYT),  Chile.	Fig.  2.  Time  series  of  upwelling  index  (upper),  temperature  and  D.  acuta  cell  densities  recorded   from   4   September   to   31   October   at   Ría   de   Vigo   (middle)   and   Ría   de  Pontevedra  (lower)  monitoring  stations.  	During   the   ﬁrst   cruise   (13   Sept.)   there  was   an  oﬀshore   Ekman   transport   generated   by  northerly   winds   (Fig.1).   From   20   to   30  September   there   was   a   wind   shift   and  southerlies   became   predominant   resulting   in  onshore   Ekman   transport   and   a   signiﬁcant  increase  of   temperature  with  maximum  values  close   to   19°C   at   surface   (Fig.   2).   Results   from  the   second   mini-­‐‑cruise   (27   Sept.)   showed   a  dense   bloom   of   D.   acuta   with   its   maxima  associated  with  strong  thermal  gradients   (Figs.  3-­‐‑4).   In   the   outer  Rías,   the   autumn  peak   of  D.  acuta   was   detected   5-­‐‑d   before   that   of   G.  catenatum,   suggesting   diﬀerent   distribution   of  the  source  populations.	Conclusions	•  Persistent  thermal  stratiﬁcation  (1-­‐‑2  months)  combined  with  moderate  upwelling  during  mid-­‐‑late  summer  1990  in  the  Galician  shelf  created  the  conditions  for  unusual  summer  blooms  of  D.  acuta.  	•  Maximum   cell   densities   of  D.   acuta,   vertically   segregated   from   G.   catenatum  maxima,  were   observed   at   the  maximum  thermal  gradient.	•  D.  acuta  was  restricted  to  a  narrow  band  of  20  km  on  the  shelf  (stations  between  50-­‐‑130    m  isobaths).	•  A  5-­‐‑d   time   lag  was  observed  between   the  quick  onset   (presumably   resulting   from   long-­‐‑shore   transport)   of  D.  acuta  and  G.  catenatum  cell  maxima.	Fig.  4.  Vertical  proﬁles  of  salinity,  temperature  and  D.  acuta  cell  densities  during  the  three  one-­‐‑day  cruises    at  a  shelf  station.	Fig.   3.   Vertical   distribution   of   temperature   (ºC)   through   a   diagonal   (left)   and  perpendicular  (right)  transect  on  the  Galician  shelf  during  September  13,  27  and  October  11,  1990.  D.  acuta  cell  densities  are  indicated  in  the  left  panel.	0 1-100 100-1000 1000-10000 Longitude W   Longitude W   cells L-1 Maximum   cell   densities   (5.4x104   cells   l-­‐‑1)  were  found  at  20m  (15.27  °C,  35.82  psu)  on  a   shelf   station   oﬀ   Ría   de   Vigo,   with   a  vertical   gradient   of   0.2°C   m-­‐‑1   on   the   top  20m.   Our   results   suggest   that   persistent  thermal   stratiﬁcation   combined   with  moderate   upwelling   during   mid-­‐‑late  summer   1990   in   the   Galician   shelf   created  conditions   similar   to   those   in   the   gravity  centre   (oﬀ  Aveiro)   of  D.   acuta   populations  further  south  in  Portugal.	

Conditions associated with unusual summer blooms of Dinophysis acuta in an upwelling area.

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Conditions associated with unusual summer blooms of Dinophysis acuta in an upwelling area

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