Thresholds of Adverse Effects of Macroalgal Abundance and Sediment Organic Matter on Benthic Habitat Quality in Estuarine Intertidal Flats

Sutula, Martha; Green, Lauri; Cicchetti, Giancarlo; Detenbeck, Naomi E.; Fong, Peggy

doi:10.1007/s12237-014-9796-3

Cited by 28 publications

(30 citation statements)

References 48 publications

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“…Other studies which sampled sediments in the AHE (Burge 2007;Bolton-Ritchie 2015;Robertson et al 2015) also found low %OM and %C and %N. The low AHE %C values were within the 'reference condition' ranges defined for healthy sediments in Californian lagoon-type estuaries by Sutula et al (2014): 0.2-0.7%, and by Pelletier et al (2011): 0.2-0.9% for eastern US estuaries. These %C values were well below the 'enrichment thresholds' range of 1-1.5% defined by Sutula et al (2014) to cause impairment of macrobenthic communities, and below the threshold defined for incipient macrobenthic impairment by Robertson et al (2016) of 1.2%, using a large dataset of NZ lagoon-type estuaries.…”

Section: Sediment and Porewater Propertiesmentioning

confidence: 52%

“…and Gracilaria spp.) (Bolton-Ritchie and Main 2005; Barr et al 2012), as often seen in enriched shallow estuaries (Sutula et al 2014). Benthic microalgae (BMA) were also very abundant in the AHE, forming thick, highly visible films, again like other eutrophic estuaries (MacIntyre et al 1996;Tyler et al 2003).…”

Section: Introductionmentioning

confidence: 91%

“…They can be compared with higher values in other NZ estuaries (%C: 0.25-1.25; Robertson et al (2015)), Californian estuaries (%C: 0.1-9.5, %N: 0.02-0.77; Sutula et al (2014)) and Swedish estuaries (%OM: 2.6-18;Engelsen et al 2008). Other studies which sampled sediments in the AHE (Burge 2007;Bolton-Ritchie 2015;Robertson et al 2015) also found low %OM and %C and %N.…”

Section: Sediment and Porewater Propertiesmentioning

confidence: 96%

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Trophic Indicators of Ecological Resilience in a Tidal Lagoon Estuary Following Wastewater Diversion and Earthquake Disturbance

Zeldis

Depree

Gongol

et al. 2019

Estuaries and Coasts

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Estuary ecological resilience can be gauged by response of estuary trophic state to abatement of nutrient pollution. Changes in trophic indicators were studied in the Avon-Heathcote Estuary (AHE) in Christchurch, New Zealand, over 6 years, spanning diversion of city wastewater inputs to an offshore outfall in 2010, and to temporary enrichment caused by the 2011 Christchurch earthquake. It was hypothesised that the tidally well-flushed and sandy AHE would not harbour a 'legacy' of eutrophication and would rapidly gain improved ecological function following the diversion. AHE sediments were coarse (156 μm median grain size) with low organic matter (OM 1.2%, N 0.03%, C 0.3%), which changed little either with diversion or earthquake. Upon diversion, median water column and porewater ammonium (36, 185 μmol) decreased by 87% and 57%, respectively, benthic microalgae (269 mg chlorophyll-a m −2) fell by 58%, and enrichment-affiliated polychaetes (3700-8000 m −2) fell by 60-80% at sites with largest benthic microalgal reductions, all within < 1-2 years. Oxygen and ammonium fluxes were usually oligotrophic and changed little upon diversion, except near the historic wastewater discharge site. Denitrification became more important for N loss, increasing from 5 to 29% of estuary N load. Responses to earthquake-driven enrichment were transient. Despite decades of heavy N loading and eutrophic growths of benthic microalgae and macroalgae, the AHE did not store a eutrophic legacy in its sediments. It reacted rapidly to improved water quality allowed by the outfall, showing that this common estuary type (sandy, well-flushed tidal lagoon) was resilient to eutrophication upon stressor removal.

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Section: Sediment and Porewater Propertiesmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 91%

Section: Sediment and Porewater Propertiesmentioning

confidence: 96%

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Trophic Indicators of Ecological Resilience in a Tidal Lagoon Estuary Following Wastewater Diversion and Earthquake Disturbance

Zeldis

Depree

Gongol

et al. 2019

Estuaries and Coasts

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“…Methods and results of surveys to determine abundances of macroalgae used in the three experimental treatments (1, 3 and 12 kg ww m −2 ) are presented in Supplementary material Appendix 3. These treatments were within the range of macroalgal densities found across intertidal flats on California (Sutula et al ) and the Pacific northwest of the United States (Nelson et al ). All macroalgal treatments were comprised of U. intestinalis as that was the only alga found in the lagoon at the time.…”

Section: Methodsmentioning

confidence: 93%

“…Additionally, the microphytobenthos (MPB), an important producer community which consists of epipelic bacteria, diatoms (Sdrigotti and Welker ) and sporeling macroalgae living on the sediment surface (Sundback et al , ), may be negatively affected by persistent macroalgal cover (Sundback et al ). Thus far, field surveys examining thresholds of macroalgal abundance on benthic habitat characteristics lacked data on the macrobenthic community (Sutula et al ), whereas experiments evaluating effects of macroalgae on the benthic community (Hull , Green et al ) lacked causal mechanisms to explain shifts in macrobenthic community structure. Finally, researchers who evaluated the effects of macroalgal abundance on stimulating sediment pore water sulfides utilized presence absence studies (Auffrey et al , Gribben et al ) and mesocosms (Nedergaard et al ) rather than density dependent field experiments that could identify thresholds at which macroalgae shifts from positive to negative effects.…”

mentioning

confidence: 99%

The good, the bad and the Ulva: the density dependent role of macroalgal subsidies in influencing diversity and trophic structure of an estuarine community

Green¹,

Fong²

2015

Oikos

Self Cite

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Worldwide, ecological subsidies enhance ecosystem productivity and therefore trophic support for greater biodiversity of taxa. While studies in terrestrial and aquatic ecosystems demonstrate that the magnitude of subsidies into ecosystems diff ers widely, the thresholds where subsidies may switch from exerting positive to negative eff ects are poorly understood. In estuaries, eutrophication promotes drift macroalgae that deposit on the benthos, cover intertidal fl ats for months and serve as pressed resource subsidies for benthic consumers. We hypothesized there would be a critical threshold of macroalgal biomass where ecosystem-level eff ects would turn from positive to negative. We used manipulative fi eld experiments varying macroalgal mat thickness (0.5, 1.5 and 4 cm) over eight weeks and quantifi ed eff ects on macrofauna on a lagoon mudfl at in California. We documented that plots with mat depths of 0.5 and 1.5 cm had higher diversity by supporting both surface feeding and burrowing detritivores. Non-metric multidimensional scaling showed that the benthic community diverged with mat depth over the course of the experiment. After eight weeks, surface deposit feeders were associated mainly with 0.5 cm macroalgal subsidies, whereas subsurface deposit feeding capitellids were closely linked with 4 cm mats. Depth profi les of pore water sulfi de concentration collected from 4 cm mats were 7622 Ϯ 5294 μ M, mean Ϯ SE, (mean of means across depth profi les), whereas 0.5 cm treatments resulted in sulfi de concentrations that were 0.25% of the 4 cm treatments. Th is suggests that the mechanism of negative eff ects for elevated macroalgal subsidies was development of anoxic conditions promoting sulfi de accumulation. Th us, our study was the fi rst to fi nd a critical threshold, or ecological tipping point, beyond which the eff ects of anthropogenically enhanced subsidies to estuarine mudfl at communities switched from positive to negative and to describe the mechanism by which elevated subsides altered the abiotic environment and likely reduced ecosystem functioning.

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Harmful Macroalgal Blooms in a Changing World: Causes, Impacts, and Management

Lapointe

Burkholder

Alstyne

2018

Harmful Algal Blooms

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Thresholds of Adverse Effects of Macroalgal Abundance and Sediment Organic Matter on Benthic Habitat Quality in Estuarine Intertidal Flats

Cited by 28 publications

References 48 publications

Trophic Indicators of Ecological Resilience in a Tidal Lagoon Estuary Following Wastewater Diversion and Earthquake Disturbance

Trophic Indicators of Ecological Resilience in a Tidal Lagoon Estuary Following Wastewater Diversion and Earthquake Disturbance

The good, the bad and the Ulva: the density dependent role of macroalgal subsidies in influencing diversity and trophic structure of an estuarine community

Harmful Macroalgal Blooms in a Changing World: Causes, Impacts, and Management

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