Mass fish die-off during a diatom bloom in the Bahia de La Paz, Gulf of California

作者：Javier Lopez Cortes David; Julian Nunes Vazquez Erick; Johanna Band Schmidt Christine; Garate Lizarraga Ismael; Eduardo Hernandez Sandoval Francisco; Jesus Bustillos Guzman Jose

来源：Hidrobiologica, 2015, 25(1): 39-48.

• Domoic acid
• fish mortality
• Gulf of California
• Pseudo-nitzschia
• Thalassiosira

An unusual fish die-off occurred during a bloom of diatoms from June 10th-July 3rd 2006 in Bahia de La Paz in the Gulf of California. The prevalent organisms were Pseudo-nitzschia spp. (2.4 x 10(6) cells L-1), Thalassiosira eccentrica (2.3 x 10(6) cells L-1) and Chaetoceros spp. (9.65 x 10(5) cells L-1). Three toxic species were identified: P pseudodelicatissima-complex, P fraudulenta, and P. pungens. Fucoxanthin was the dominant pigment during the bloom, peaking at 9.3 mu g L-1. Sea surface temperature dramatically increased from 19.0 degrees C to 27.0 degrees C during the bloom, with inorganic nitrogen (1.0 +/- 0.6 mu M) and Si(OH)(4) (15.5 +/- 8.0 mu M). Low content of domoic acid measured by HPLC-UV from net samples ranged from 24.0 to 52.0 ng per filter and tissue of the chocolate clam Megapitaria squalida (0.55 mu g g(-1)) and the white clam Dosinia ponderosa (0.06 mu g g(-1)). Domoic acid analysis of dead fish tissues was negative. Fish necropsy indicated that death by asphyxia was probably caused by Thalassiosira eccentrica and Chaetoceros spp. Alternate mixing processes and instability of the water column, as well as sudden changes of both temperature and nutrients created conditions for proliferation of the diatoms.

• 出版日期2015-4