22
A.B. Goya and S. Maldonado
According to a study conducted during 2006 and 2007 (Almandoz et al. 2011),
low phytoplankton densities were present in the channel during fall and winter.
The phytoplankton was mainly composed of unidentified tiny phytoflagellates. By
late spring, large species of dinoflagellates increased in biomass, representing about
50 % of the total phytoplankton biomass in December. One of the species identified
was A. catenella.
PSP outbreaks in molluscs which began in the spring of 2009 and 2010 reached
toxicity peaks just in late February 2010 and 2011. These findings may indicate
that episodes of toxic blooms could have extended in time. On the other hand, the
persistence of unusually high toxicity through the autumn and early winter could
be due to low water temperatures which, by lowering shellfish metabolic activity,
decrease the rate of shellfish detoxification.
Conclusions
Until 1992, the Beagle Channel was considered to be free of toxicity episodes
caused by biotoxins, which impacted positively on the commercial harvesting
activities of molluscs. Harvest volumes were significant and in the years 1989, 1990
and 1991, it exceeded coastal fish catches (Subsecretar´ ıa de Recursos Naturales
y Ambiente Humano, Tierra del Fuego, Argentina n.d.). The toxic bloom which
occurred in January 1992 constituted a watershed in the sanitary management of
shellfish harvesting areas. Since then, monitoring activities have intensified, and a
large number of samples need to be analyzed periodically in order to safeguard
public health. Additionally, due to an unusual persistence of toxicity in molluscs
during 2010 and 2011, many areas had to remain closed until winter. A consequence
of this situation is that shellfish harvesting periods have been shortened, with
consequential economic losses for producers. The potential sanitary consequences
call for a closer monitoring of this phenomenon. Effective monitoring plans for
molluscs have been carried out by sanitary authorities, who have implemented
all necessary safety measures to protect public health. However, there is little
information on the phytoplankton species involved in toxic outbreaks, and there is
no current data on toxin profiles in contaminated molluscs. Future toxin monitoring
efforts should include regular analysis of phytoplankton samples along with the
monitoring of toxins in shellfish as well as retrieval of data that provide further
insight into the nature of toxic events.
Acknowledgments The authors thank Andrea Rossini, D´ ebora Bellonio, Ana Luz Candelo and
Sergio Ledo for their help with data processing. The authors are also grateful to Ms. Silvina Parma
for valuable assistance with maps design as well as the valuable contribution provided by the staff
of the Centre for Documentation and Information (CdeI) of SENASA.
A.B. Goya and S. Maldonado
According to a study conducted during 2006 and 2007 (Almandoz et al. 2011),
low phytoplankton densities were present in the channel during fall and winter.
The phytoplankton was mainly composed of unidentified tiny phytoflagellates. By
late spring, large species of dinoflagellates increased in biomass, representing about
50 % of the total phytoplankton biomass in December. One of the species identified
was A. catenella.
PSP outbreaks in molluscs which began in the spring of 2009 and 2010 reached
toxicity peaks just in late February 2010 and 2011. These findings may indicate
that episodes of toxic blooms could have extended in time. On the other hand, the
persistence of unusually high toxicity through the autumn and early winter could
be due to low water temperatures which, by lowering shellfish metabolic activity,
decrease the rate of shellfish detoxification.
Conclusions
Until 1992, the Beagle Channel was considered to be free of toxicity episodes
caused by biotoxins, which impacted positively on the commercial harvesting
activities of molluscs. Harvest volumes were significant and in the years 1989, 1990
and 1991, it exceeded coastal fish catches (Subsecretar´ ıa de Recursos Naturales
y Ambiente Humano, Tierra del Fuego, Argentina n.d.). The toxic bloom which
occurred in January 1992 constituted a watershed in the sanitary management of
shellfish harvesting areas. Since then, monitoring activities have intensified, and a
large number of samples need to be analyzed periodically in order to safeguard
public health. Additionally, due to an unusual persistence of toxicity in molluscs
during 2010 and 2011, many areas had to remain closed until winter. A consequence
of this situation is that shellfish harvesting periods have been shortened, with
consequential economic losses for producers. The potential sanitary consequences
call for a closer monitoring of this phenomenon. Effective monitoring plans for
molluscs have been carried out by sanitary authorities, who have implemented
all necessary safety measures to protect public health. However, there is little
information on the phytoplankton species involved in toxic outbreaks, and there is
no current data on toxin profiles in contaminated molluscs. Future toxin monitoring
efforts should include regular analysis of phytoplankton samples along with the
monitoring of toxins in shellfish as well as retrieval of data that provide further
insight into the nature of toxic events.
Acknowledgments The authors thank Andrea Rossini, D´ ebora Bellonio, Ana Luz Candelo and
Sergio Ledo for their help with data processing. The authors are also grateful to Ms. Silvina Parma
for valuable assistance with maps design as well as the valuable contribution provided by the staff
of the Centre for Documentation and Information (CdeI) of SENASA.