Temporal and spatial variability in the characteristics of Alexandrium fundyense blooms in the coastal zone of the Bay of Fundy, eastern Canada

Abstract

The abundance of the dinoglagellate Alexandrium fundyense has been monitored at four locations in the Bay of Fundy, eastern Canada, at weekly to monthly intervals since 1988. The date of first appearance of A. fundyense varied each year from Day 105 to Day 179. Between stations, the mean and median dates of first appearance of A. fundyense varied by only a few days. Overall, the mean (median) date of first appearance was Day 136 (134). The null hypothesis that the date of first appearance varies randomly from year to year could not be rejected (α = 0.05) by a two-sided runs test. The date of maximum cell concentration varied, between stations and years, by about 30 days. Maximum cell concentrations occurred earliest at the inshore estuarine station (Day 172–175) and latest offshore (Day 197–203). The annual maximum concentration of A. fundyense varied among stations by about three orders of magnitude and the median value differed from offshore to inshore by about two orders of magnitude. The total annual duration of the presence of A. fundyense ranged from 50 days to 200 days and had a mean of 120 days, whereas the duration of the bloom containing the annual maximum concentration varied from 10 days to 160 days. The temporal character of the A. fundyense bloom also varied between years and stations with the number of blooms or abundance pulses varying from one per year to three per year.