In:
Journal of the Marine Biological Association of the United Kingdom, Cambridge University Press (CUP), Vol. 97, No. 7 ( 2017-11), p. 1483-1494
Abstract:
Spatial and temporal variability and bloom formation of the potentially toxic diatom Pseudo-nitzschia spp. was investigated weekly to monthly from October 2009 to October 2010 in a eutrophic estuary, the Golden Horn. Pseudo-nitzschia spp. were detected in 195 of 512 samples (38%) collected throughout the year. Two species, P. calliantha and P. pungens , were identified based on the SEM examination. Blooms of Pseudo-nitzschia occurred in the lower and middle estuary in January and May. The bloom in January mainly comprised P. calliantha . In the bloom in early May, P. calliantha made up 72% of the Pseudo-nitzschia cells and P. pungens 28%. However, the contribution of P. pungens increased to 83% in late May. The Pseudo-nitzschia blooms occurred at low temperature (9–15°C) and moderate salinity (17–18), and for P. calliantha a significant negative correlation was found with temperature and a significant positive correlation with salinity. The percentage of Pseudo-nitzschia cells decreased gradually from lower to upper estuary (59–14%), correlating with a decrease in Secchi depth (5.5–0.5 m). Principal components analyses (PCA) were used to explore the spatial and temporal variability of environmental factors in relation to Pseudo-nitzschia abundances, and showed that NH 4 , pH, Secchi depth and DO values were the most important factors reflecting spatial differences, while temperature, salinity, Chl- a and Si:N were more important factors showing temporal differences. High abundances of P. pungens correlated mainly with pH, Secchi depth and DO values, whereas P. calliantha also correlated with NO 3 + NO 2 . Low light availability due to high concentrations of suspended material and very variable environmental conditions (e.g. pH, DO and NH 4 ) may have limited growth of Pseudo-nitzschia in the upper estuary. Regular monitoring of Pseudo-nitzschia is important for improving the understanding of the influence of environmental parameters on bloom dynamics in the study area.
Type of Medium:
Online Resource
ISSN:
0025-3154
,
1469-7769
DOI:
10.1017/S0025315416000837
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2017
detail.hit.zdb_id:
1491269-7
detail.hit.zdb_id:
281325-7
SSG:
12
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