Short-Term Dinoflagellate Bloom in a Shrimp Pond in Bahía de La Paz, Gulf of California

From mid-August to mid-September 1998, a dinoflagellate bloom in a shrimp pond near La Paz, Baja California Sur, was studied. Daily samples were taken of phytoplankton, dissolved oxygen, nutrient concentrations, photosynthetic pigments and proteins. The bloom occurred at temperatures of 29.7 to 33.2 °C. High densities of a Scrippsiella-like dinoflagellate (15.9 × 10 ⁶ cells/L) occurred on the first day of sampling, reaching a peak of 249 × 10 ⁶ cells/L on Day 13, and declining to 4 to 7 × 10 ⁶ cells/L by Day 26. Chlorophyll a varied from 8.63 mg/m ³ on Day 4 to 141.38 mg/m ³ on Day 13. Total nitrogen varied widely (0.2-11.50 μM) while phosphates peaked only once on Day 13 (4.14 μM). Proteins ranged from 523 to 6387 μg/L; the latter value occurred two days after the maximal peak of nitrates and coinciding with the highest level of phosphates. Fertilizers added to the ponds increased nutrient concentration and stimulated phytoplankton growth. In turn, the food supply to cultured shrimp noticeably increased throughout the bloom.