Assessing the impact of nutrient enrichment in estuaries: Susceptibility to eutrophication

Painting, S. J.; Devlin, Michelle; Malcolm, S.J.; Parker, E. R.; Mills, Dave; Mills, Craig; Tett, Paul; Wither, A.; Burt, J.; Jones, R. I.; Winpenny, K.

doi:10.1016/j.marpolbul.2006.08.020

Cited by 110 publications

(60 citation statements)

References 16 publications

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“…These can have negative consequences for the timing of phytoplankton bloom initiation, magnitude of primary production, composition of the phytoplankton community composition and the organization of pelagic food webs, for example, shifting the phytoplankton toward harmful algal species. Estuaries are particularly susceptible to nutrient enrichment (e.g., Painting et al 2007;Cloern 2001) and cultural eutrophication, an increase in organic matter production resulting from anthropogenic activity such as fertilizer runoff or sewage discharge (e.g., Fisher et al 2006).…”

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confidence: 99%

Nutrient uptake and primary productivity in an urban estuary: using rate measurements to evaluate phytoplankton response to different hydrological and nutrient conditions

et al. 2015

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The northern San Francisco Estuary (nSFE) is an urban estuary supplied with anthropogenic nutrient inputs, yet spring blooms are uncommon and phytoplankton biomass is low. The low levels of chlorophyll (\5 lg L -1 ) have likely contributed to declines in several native fishes, and there is a need to evaluate the conditions that could allow for increased phytoplankton. Increased ammonium (NH 4 ) loads have been hypothesized to modulate the magnitude of blooms in nSFE (the ''NH 4 hypothesis'') as a result of inhibition of phytoplankton NO 3 uptake that limits access to the greater nitrogen (N) pool of nitrate (NO 3 ). This hypothesis, tested in enclosures, but not in the field until now, is that lack of access to NO 3 limits primary production and consequently the accumulation of chlorophyll. Here, we test this in the field with the following aims: (1) to observe the uptake response of phytoplankton in different flow and N loading conditions, (2) determine whether the sequence of uptake rates suggested by the ''NH 4 hypothesis'' occurs and (3) obtain depth-integrated nutrient uptake rates to better constrain published criteria for bloom formation. Weekly measurements of NH 4 and NO 3 uptake, and primary production rates were made during spring 2011-2012, along with nutrient and chlorophyll concentrations during two contrasting hydrological conditions of high vs low freshwater flow. In conditions with high freshwater flow (maximum of 2405 m 3 s -1 ), there were lower nutrient concentrations than with low/normal flows (e.g., NO 3 of 10 lmol L -1 compared to 30 lmol L -1 ), with low N uptake and primary production rates. With low flow (maximum of 1304 m 3 s -1 ), there was elevated chlorophyll and blooms occurred, especially in shallow well-lit shoals where chlorophyll reached 60 lg L -1 . The higher levels of chlorophyll and primary productivity resulted from uptake of ambient NO 3 by phytoplankton, and f-ratios [0.5. This was enabled by phytoplankton uptake of NH 4 to below inhibitory levels, as proposed by the ''NH 4 hypothesis.'' The depth-integrated uptake rate data were used to refine a model that yields flow and nutrient concentration criteria necessary for bloom formation and confirmed that washout flows were the most useful predictor of blooms. Understanding the interaction of phytoplankton biomass with nutrient variability requires evaluating changes in C and N uptake rates and river flow. These dynamic changes are central to understanding why some urban estuaries have lower productivity than expected, and would be difficult to Handling Editor: Bas W. Ibelings. evaluate using biomass data alone. This study points to the importance of treating inorganic N separately as NH 4 and NO 3 rather than lumping together as DIN and to use rate process data as a mechanistic way to understand, predict and minimize cultural eutrophication impacts.

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confidence: 99%

Nutrient uptake and primary productivity in an urban estuary: using rate measurements to evaluate phytoplankton response to different hydrological and nutrient conditions

et al. 2015

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“…These small coastal lagoons are closed seasonally to surface water due to the formation of sand-bars at their inlets during low freshwater inflow periods (Webb et al 1991;Largier et al 1996). Consequently, they are "lentic," with fresh to brackish water salinity regimes during closure, and increased susceptibility to eutrophication due to restricted flushing (Painting et al 2007;Zaldivar et al 2009). Urbanization of semi-arid Southern California coastal watersheds caused the import of water from Northern California and the Colorado River, dramatically changing regional water budgets and extending dry season river flow late into the season.…”

Section: Study Areamentioning

confidence: 99%

Screening Assessment of Cyanobacteria and Cyanotoxins in Southern California Lentic Habitats

Magrann

Meredith

Sutula

et al. 2015

EMSD

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Harmful bloom-forming cyanobacteria (CyanoHABs) and associated toxins are increasingly prevalent world-wide. We conducted a screening-level study to determine if cyanobacteria and associated cyanotoxins were present in Southern California coastal lakes, ponds, and seasonally tidal lagoons. We evaluated waterbody nutrient status and physiochemical parameters, land use, waterbody type, and habitat type, to determine their utility as screening factors for risk of CyanoHAB blooms. One-time grab samples were collected from 30 sites during July-September 2009. Samples were analyzed for phytoplankton taxonomic composition, nutrients, other physiochemical parameters, and three cyanotoxins: microcystins (MCY), anatoxin-a, and cylindrospermopsin. Cyanobacteria was the predominant taxonomic group in most water bodies in this study, and Microcystis spp. was the predominant genus in 96% of the study sites. Cyanobacteria were equally prevalent among coastal lagoons, depressional wetlands, and lakes in this study. We detected MCY in high concentrations in 10% of our sites, but neither anatoxin-a nor cylindrospermopsin were detected. All of the MCY-positive sites exceeded California action levels for recreational use and World Health Organization (WHO) guidance for human health effects. The prevalence of Microcystis spp. from all study sites indicates a high potential for MCY in these water bodies, although the one-time toxin grab samples likely underestimated the overall toxicity of these sites. Landscape variables, such as developed land use and dominant habitat type, were not found to be predictive indicators of cyanobacterial dominance. However, because cyanobacteria become consistently dominant when chlorophyll-a levels exceed 15 µg L -1 , chlorophyll-a can serve as a significant predictor of MCY.

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“…For example, Devlin et al (2007) propose incorporation of indices of pressure (nutrient concentrations), state (potential primary productivity) and impact (oxygen depletion) into a hierarchy such that high nutrient inputs alone, without evidence of excessive primary production, will define water as good rather than high quality, while if there is also elevated primary production the water body will be defined as moderate or poorer quality. This enables the susceptibility of waters to respond to high nutrient inputs, identified by Painting et al (2007), and linked to light availability and water residence times, to be taken into consideration. Similar indices are being developed with respect to a range of parameters that may be affected by excessive nutrient inputs including benthos and attached macroalgae (Borja et al, 2007;Wilkinson et al, 2007).…”

Section: Nutrient Enrichment and The Occurrence Of Eutrophic Conditiomentioning

confidence: 99%

Estuarine eutrophication in the UK: current incidence and future trends

Maier

Nimmo-Smith

Glegg

et al. 2008

Aquatic Conservation

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ABSTRACT1. Increased inputs of nutrients to estuaries can lead to undesirable effects associated with eutrophication, including algal blooms, changes in species composition and bottom anoxia. Several estuaries and coastal areas around the UK have increased nitrogen (N) and phosphorus (P) concentrations, elevated concentrations of chlorophyll a and changes in algal community composition and abundance. This paper reviews the pressures that lead to high nutrient concentrations in estuaries and considers the likely effectiveness of current and proposed regulatory actions.2. The main sources of nutrients to estuaries are river runoff, sewage discharges, atmospheric inputs and possibly submarine groundwater discharges, although little is known about the latter. Significant reductions in N and P inputs have been realized following application of the EU's Urban Waste Water Treatment Directive. Atmospheric NO x and NH x emissions have also decreased and are expected to decrease further in the next decade as implementation of existing legislation continues, and new controls are introduced for activities such as shipping.3. Agricultural inputs reach estuaries principally through diffuse sources, either in surface water (and in some areas possibly groundwater) or, for N, via the atmosphere. Over 10 years ago the Nitrates Directive was introduced to tackle the problem of N discharges from agriculture but little change in N loads to estuaries has been recorded.4. To meet the aims of the EU Water Framework Directive, for at least 'good' ecological status, more rigorous application and implementation of the Nitrates Directive, together with changes in the Common Agriculture Policy and farming practice are likely to be needed. Even then, the slow response of the natural environment to change and the inherent variability of estuaries means that their responses may not be as predicted. Research is needed into the relationship between policy drivers and environmental responses to ensure actions taken will achieve the planned results.

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Assessing the impact of nutrient enrichment in estuaries: Susceptibility to eutrophication

Cited by 110 publications

References 16 publications

Nutrient uptake and primary productivity in an urban estuary: using rate measurements to evaluate phytoplankton response to different hydrological and nutrient conditions

Nutrient uptake and primary productivity in an urban estuary: using rate measurements to evaluate phytoplankton response to different hydrological and nutrient conditions

Screening Assessment of Cyanobacteria and Cyanotoxins in Southern California Lentic Habitats

Estuarine eutrophication in the UK: current incidence and future trends

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