18
A.B. Goya and S. Maldonado
Results
High levels of toxicity that occurred during the summer of 1992 throughout the
Channel, declined gradually in subsequent months, although they rarely fell below
80 g STX eq.100 g
1 . The toxicity levels reported in molluscs from several areas
of the channel during February 1992 reached particularly high values in Bah´ ıa
Golondrina and Bah´ ıa Ensenada (Table 2.1).
From that exceptional year onwards there was an upward trend in PSP toxicity in
shellfish sampled from October to November, with peaks in December, January or
February (Table 2.2), with a subsequent decrease during the autumn. An exception
was the peak of toxicity recorded in March 1996 in Isla Redonda, although in midApril it had fallen to 59 g STX eq.100 g
1 .
In 2009, toxin levels in shellfish began to rise slightly in October, with increases
in November and December, when shellfish harvesting was banned along the
entire Beagle Channel. During January and February, 2010, high PSP levels were
recorded, reaching a toxicity peak in late February (5,600 g STX eq.100 g
1 ). The
toxicity decreased slowly during the autumn and early winter. At several points the
values remained above 80 g STX eq.100 g
1 up to the end of July and several
collection areas had to remain closed for longer than in previous years. In the period
spanning from spring 2010 to summer 2011 a similar pattern was observed, with
high concentrations of PSP between January and February, and retention levels in
molluscs above the safety limit being recorded until May.
Figures 2.2 and 2.3 show the results in samples from two areas of the Channel,
Bah´ ıa Brown and Punta Paran´ a, where this pattern is readily observable.
In Table 2.2, the two lines for years 2009 and 2010 represent a two-step rise
in PSP levels with a first peak detected in Dec 14, 2009 which was followed by a
plateau ending in a second peak in Feb 22, 2010. PSP levels fell back to safe levels
in July, 2010.
Table 2.1 Levels of PSP
recorded from several zones
along the Beagle Channel
during February 1992
Date
Molluscs
Zone
PSP level
02/02/92 Aulacomya ater
I. Up´ u
4,342
02/02/92 M. edulis chilensis Pta. Paran´ a
5,524
02/04/92 M. edulis chilensis Is. Bridges
44,119
02/05/92 M. edulis chilensis B. Golondrina 120,846
02/07/92 M. edulis chilensis B. Ensenada
86,201
02/18/92 M. edulis chilensis Almanza
22,120
02/18/92 M. edulis chilensis Ea. Harberton
22,647
02/20/92 M. edulis chilensis Moat
51,984
02/20/92 Aulacomya ater
P. Guaran´ ı
12,632
02/24/92 M. edulis chilensis B. Lapataia
48,790
PSP levels are expressed in g STX eq.100 g
1
A.B. Goya and S. Maldonado
Results
High levels of toxicity that occurred during the summer of 1992 throughout the
Channel, declined gradually in subsequent months, although they rarely fell below
80 g STX eq.100 g
1 . The toxicity levels reported in molluscs from several areas
of the channel during February 1992 reached particularly high values in Bah´ ıa
Golondrina and Bah´ ıa Ensenada (Table 2.1).
From that exceptional year onwards there was an upward trend in PSP toxicity in
shellfish sampled from October to November, with peaks in December, January or
February (Table 2.2), with a subsequent decrease during the autumn. An exception
was the peak of toxicity recorded in March 1996 in Isla Redonda, although in midApril it had fallen to 59 g STX eq.100 g
1 .
In 2009, toxin levels in shellfish began to rise slightly in October, with increases
in November and December, when shellfish harvesting was banned along the
entire Beagle Channel. During January and February, 2010, high PSP levels were
recorded, reaching a toxicity peak in late February (5,600 g STX eq.100 g
1 ). The
toxicity decreased slowly during the autumn and early winter. At several points the
values remained above 80 g STX eq.100 g
1 up to the end of July and several
collection areas had to remain closed for longer than in previous years. In the period
spanning from spring 2010 to summer 2011 a similar pattern was observed, with
high concentrations of PSP between January and February, and retention levels in
molluscs above the safety limit being recorded until May.
Figures 2.2 and 2.3 show the results in samples from two areas of the Channel,
Bah´ ıa Brown and Punta Paran´ a, where this pattern is readily observable.
In Table 2.2, the two lines for years 2009 and 2010 represent a two-step rise
in PSP levels with a first peak detected in Dec 14, 2009 which was followed by a
plateau ending in a second peak in Feb 22, 2010. PSP levels fell back to safe levels
in July, 2010.
Table 2.1 Levels of PSP
recorded from several zones
along the Beagle Channel
during February 1992
Date
Molluscs
Zone
PSP level
02/02/92 Aulacomya ater
I. Up´ u
4,342
02/02/92 M. edulis chilensis Pta. Paran´ a
5,524
02/04/92 M. edulis chilensis Is. Bridges
44,119
02/05/92 M. edulis chilensis B. Golondrina 120,846
02/07/92 M. edulis chilensis B. Ensenada
86,201
02/18/92 M. edulis chilensis Almanza
22,120
02/18/92 M. edulis chilensis Ea. Harberton
22,647
02/20/92 M. edulis chilensis Moat
51,984
02/20/92 Aulacomya ater
P. Guaran´ ı
12,632
02/24/92 M. edulis chilensis B. Lapataia
48,790
PSP levels are expressed in g STX eq.100 g
1