Emergence of Algal Blooms: The Effects of Short-Term Variability in Water Quality on Phytoplankton Abundance, Diversity, and Community Composition in a Tidal Estuary

<p>Aquaculture is the fastest growing industry in the food sector and demand for aquaculture products is continuing to grow as many wild stocks from capture fisheries continue to decline. It is imperative that water quality in an aquaculture system is closely controlled in order to maintain the health of the species under culture and maximize production. New Zealand Prawns Limited (NZPL) is an aquaculture facility in Wairakei, New Zealand that cultures the freshwater prawn Macrobrachium rosenbergii. Dramatically reduced yields of prawns have been observed in ponds following periodic blooms of benthic algae. In this study, water quality variables were measured in grow out ponds at 9-11 day intervals. I measured temperature, phytoplankton abundance, phytoplankton diversity, turbidity, and concentrations of ammonia, nitrate, orthophosphate, dissolved oxygen and chlorophyll a. This data was combined with information on pond depth and prawn yield in order to investigate what variables influence the abundance and diversity of phytoplankton, benthic algal blooms and prawn yield. The difficulty of combining scientific endeavour with commercial enterprises resulted in only a small data set being available for analysis but it appears that benthic algal blooms at NZPL may be due to excessive light penetration to the benthos due to shallow pond depths, and reduced shading of the benthos when phytoplankton abundance is low. Low phytoplankton abundance may possibly be a result of low orthophosphate. There was insufficient data to determine what impacts, if any, the variables investigated have on prawn yield or how water quality variables change with time. Future studies and experiments are recommended in order to increase knowledge of farming M. rosenbergii; a valuable crustacean that has been shown to have a lower social and environmental impact than many other more common aquaculture species.</p>

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Long-term trends and short-term variability of water quality in Skive Fjord, Denmark – nutrient load and mussels are the primary pressures and drivers that influence water quality

Environmental Monitoring and Assessment ◽

10.1007/s10661-006-9298-2 ◽

2006 ◽

Vol 127 (1-3) ◽

pp. 503-521 ◽

Cited By ~ 19

Author(s):

F. Møhlenberg ◽

S. Petersen ◽

A. H. Petersen ◽

C. Gameiro

Keyword(s):

Water Quality ◽

Nutrient Load ◽

Short Term ◽

Long Term Trends ◽

Short Term Variability

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Study of the seasonality and hydrology as drivers of phytoplankton abundance and composition in a shallow estuary, Weeks Bay, Alabama (USA)

Journal of Aquaculture & Marine Biology ◽

10.15406/jamb.2019.08.00245 ◽

2019 ◽

Vol 8 (3) ◽

Author(s):

Lucie Novoveská

Keyword(s):

Chlorophyll A ◽

Community Composition ◽

River Discharge ◽

Algal Blooms ◽

Harmful Algal Bloom ◽

Land Use Changes ◽

Nutrient Concentrations ◽

Phytoplankton Abundance ◽

Weeks Bay ◽

Shallow Estuary

Small, shallow estuaries can be highly vulnerable to land use changes, eutrophication and habitat loss but are understudied with respect to their larger counterparts. Where they are monitored, the descriptors of their environmental status are typically chlorophyll a as a proxy for phytoplankton abundance and nutrient concentration as a presumed driver of the phytoplankton community. We present data from a shallow estuary, Weeks Bay, Alabama (USA), that demonstrates that chlorophyll a and nutrient concentrations are inadequate descriptors of ecological state. Weeks Bay had relatively high nutrient concentrations (86–169µM total nitrogen and 1.0–5.2µM total phosphorus) and highly variable chlorophyll a concentrations (2.2–160.5μgL-1). The variability in chlorophyll a was most highly correlated with nutrient levels and river discharge. There was no relationship between chlorophyll a and community composition. Two of three maxima in chlorophyll a (> 100 μgL-1) were caused by non-toxic chlorophytes and diatoms; the third was dominated by potentially toxic raphidophyte Heterosigma akashiwo. The phytoplankton were diverse even at the class level and community composition varied on both annual and inter-annual scales. The best overall descriptor of phytoplankton composition was the annual cycle in temperature, but inter-annual variability was correlated with hydrology. In the winter, dominance by dinoflagellates, including several taxa that form harmful algal blooms, was correlated with low river discharge, low turbidity and high zooplankton numbers, while dominance by diatoms was correlated with high and variable river discharge and high turbidity. In the summer, dominance by cryptophytes versus diatoms was consistent with changes in groundwater discharge. The dominance of harmful algal bloom taxa vs non-toxic ones could not be inferred from chlorophyll a and/or nutrient concentrations.

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The Effects of Different Water Quality Parameters on Prawn (Macrobrachium Rosenbergii) Yield, Phytoplankton Abundance and Phytoplankton Diversity at New Zealand Prawns Limited, Wairakei, New Zealand

10.26686/wgtn.16958974.v1 ◽

2021 ◽

Author(s):

◽

Daniel John MacGibbon

Keyword(s):

Water Quality ◽

New Zealand ◽

Algal Blooms ◽

Macrobrachium Rosenbergii ◽

Small Data ◽

Measured Temperature ◽

Phytoplankton Abundance ◽

Data Set ◽

Phytoplankton Diversity ◽

Water Quality Variables

<p>Aquaculture is the fastest growing industry in the food sector and demand for aquaculture products is continuing to grow as many wild stocks from capture fisheries continue to decline. It is imperative that water quality in an aquaculture system is closely controlled in order to maintain the health of the species under culture and maximize production. New Zealand Prawns Limited (NZPL) is an aquaculture facility in Wairakei, New Zealand that cultures the freshwater prawn Macrobrachium rosenbergii. Dramatically reduced yields of prawns have been observed in ponds following periodic blooms of benthic algae. In this study, water quality variables were measured in grow out ponds at 9-11 day intervals. I measured temperature, phytoplankton abundance, phytoplankton diversity, turbidity, and concentrations of ammonia, nitrate, orthophosphate, dissolved oxygen and chlorophyll a. This data was combined with information on pond depth and prawn yield in order to investigate what variables influence the abundance and diversity of phytoplankton, benthic algal blooms and prawn yield. The difficulty of combining scientific endeavour with commercial enterprises resulted in only a small data set being available for analysis but it appears that benthic algal blooms at NZPL may be due to excessive light penetration to the benthos due to shallow pond depths, and reduced shading of the benthos when phytoplankton abundance is low. Low phytoplankton abundance may possibly be a result of low orthophosphate. There was insufficient data to determine what impacts, if any, the variables investigated have on prawn yield or how water quality variables change with time. Future studies and experiments are recommended in order to increase knowledge of farming M. rosenbergii; a valuable crustacean that has been shown to have a lower social and environmental impact than many other more common aquaculture species.</p>

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