Multiple sources of nutrients add to the complexities of predicting marine benthic community responses to enrichment

O’Brien, Allyson L.; Morris, Liz; Keough, Michael J.

doi:10.1071/mf10085

Cited by 16 publications

(12 citation statements)

References 40 publications

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“…Previous studies have highlighted the role that macrophyte detrital subsidies play in structuring benthic macrofaunal communities and influencing MPB biomass on temperate intertidal flats (e.g. [ 1 , 16 , 21 , 26 , 27 ]). This study, however, is the first to measure the temporal succession of in situ benthic primary production, community metabolism, and nutrient regeneration following the addition of detritus to the sediments.…”

Section: Discussionmentioning

confidence: 99%

“…Despite these important temporal dynamics, previous studies investigating the role of detrital addition on soft sediment ecosystems have mostly considered responses that occur at one or possibly two fixed points in time (most commonly after 2–3 months; e.g. [ 4 , 9 , 16 , 17 , 21 , 26 , 27 ]). These studies reveal little about the temporal evolution in ecosystem responses to detrital subsidies associated with the changes that occur during decay.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent

et al. 2016

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Detrital subsidies from marine macrophytes are prevalent in temperate estuaries, and their role in structuring benthic macrofaunal communities is well documented, but the resulting impact on ecosystem function is not understood. We conducted a field experiment to test the effects of detrital decay on soft-sediment primary production, community metabolism and nutrient regeneration (measures of ecosystem function). Twenty four (2 m2) plots were established on an intertidal sandflat, to which we added 0 or 220 g DW m-2 of detritus from either mangroves (Avicennia marina), seagrass (Zostera muelleri), or kelp (Ecklonia radiata) (n = 6 plots per treatment). Then, after 4, 17 and 46 d we measured ecosystem function, macrofaunal community structure and sediment properties. We hypothesized that (1) detrital decay would stimulate benthic primary production either by supplying nutrients to the benthic macrophytes, or by altering the macrofaunal community; and (2) ecosystem responses would depend on the stage and rate of macrophyte decay (a function of source). Avicennia detritus decayed the slowest with a half-life (t50) of 46 d, while Zostera and Ecklonia had t50 values of 28 and 2.6 d, respectively. However, ecosystem responses were not related to these differences. Instead, we found transient effects (up to 17 d) of Avicennia and Ecklonia detritus on benthic primary production, where initially (4 d) these detrital sources suppressed primary production, but after 17 d, primary production was stimulated in Avicennia plots relative to controls. Other ecosystem function response variables and the macrofaunal community composition were not altered by the addition of detritus, but did vary with time. By sampling ecosystem function temporally, we were able to capture the in situ transient effects of detrital subsidies on important benthic ecosystem functions.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent

et al. 2016

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“…The lack of any relationships between TN ratio and sediment organic matter content regardless of grain size, is in agreement with the oligotrophic nature of Australian estuaries. Studies experimentally fertilizing sediments have found minimal impacts of enrichment on macrofaunal assemblages of south-east Australian estuaries [57], [58].…”

Section: Discussionmentioning

confidence: 99%

Weak and Habitat-Dependent Effects of Nutrient Pollution on Macrofaunal Communities of Southeast Australian Estuaries

Nicastro

Bishop

2013

PLoS ONE

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Among the impacts of coastal settlements to estuaries, nutrient pollution is often singled out as a leading cause of modification to the ecological communities of soft sediments. Through sampling of 48 sites, distributed among 16 estuaries of New South Wales, Australia, we tested the hypotheses that (1) anthropogenic nutrient loads would be a better predictor of macrofaunal communities than estuarine geomorphology or local sediment characteristics; and (2) local environmental context, as determined largely by sediment characteristics, would modify the relationship between nutrient loading and community composition. Contrary to the hypothesis, multivariate multiple regression analyses revealed that sediment grain size was the best predictor of macrofaunal assemblage composition. When samples were stratified according to median grain size, relationships between faunal communities and nitrogen loading and latitude emerged, but only among estuaries with sandier sediments. In these estuaries, capitellid and nereid polychaetes and chironomid larvae were the taxa that showed the strongest correlations with nutrient loading. Overall, this study failed to provide evidence of a differential relationship between diffuse nutrient enrichment and benthic macrofauna across a gradient of 7° of latitude and 4°C temperature. Nevertheless, as human population growth continues to place increasing pressure on southeast Australian estuaries, manipulative field studies examining when and where nutrient loading will lead to significant changes in estuarine community structure are needed.

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“…Other environmental factors, such as background nutrient loadings, may also play an important role in influencing the variable effects of wrack (O'Brien et al . ). Biological responses to wrack deposits in areas where background nutrient loadings are high ( e.g .…”

Section: Introductionmentioning

confidence: 97%

“…Wrack deposits covering large spatial extents can have widespread negative effects on benthic fauna before they start to decompose (Raffaelli 2000) and in the final stages of decomposition as they assimilate into the sediment (Rossi & Underwood 2002;Kelaher & Levinton 2003). Other environmental factors, such as background nutrient loadings, may also play an important role in influencing the variable effects of wrack (O'Brien et al 2010). Biological responses to wrack deposits in areas where background nutrient loadings are high (e.g.…”

Section: Introductionmentioning

confidence: 99%

Rapid invertebrate responses to macroalgal wrack: two novel field experiments on intertidal mudflats in Southern Australia

2016

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Macroalgal wrack deposition along coasts is highly variable but it plays an important role in the structure and function of marine communities. To date, most research has focused on the effects of decomposing wrack as it assimilates into the system but little is known about the immediate effects of wrack when it is first deposited in the habitat. Freshly deposited wrack may either wash away after a short period (1–2 days) or remain in the habitat and decay depending on tide and weather conditions. To understand the effects of this dynamic resource we experimentally manipulated wrack deposits on intertidal mudflats in Port Phillip Bay, Victoria, Australia. We conducted two experiments using defaunated patches of wrack (300 g wet weight) that were a mixture of seagrass and macroalgae and measured community responses after 2 days. The first experiment included real and artificial wrack patches to differentiate between taxa that responded to the biological and physical structure of the wrack. The second experiment used multiple wrack patches to investigate responses to a focal wrack patch that was surrounded by varying numbers of wrack additional patches (0, 2 or 4 × 300 g wet weight of wrack). Overall, wrack increased abundances of invertebrates and changed their distributions throughout the wrack and underlying sediment habitat. Mechanisms responsible for immediate taxa responses to the wrack related to the physical structure in the habitat and not biological attributes associated with the real patches. Ostracods and leptostracans were the exception to these patterns with colonization only occurring in real wrack and not the artificial wrack. In the multiple patch experiment the majority of the fauna moved vertically into the wrack from the bare sediment and not between surrounding patches of wrack. We suggest that specific characteristics, such as invertebrate mobility, feeding mode and sensitivity to changes in sediment condition, are important factors that influence individual taxa and overall community responses. Understanding the interactive effects of these characteristics with the characteristics of the wrack (magnitude, frequency, spatial arrangement and composition) is the key to developing predictive models that will inform the management of wrack in marine coastal habitats.

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Multiple sources of nutrients add to the complexities of predicting marine benthic community responses to enrichment

Cited by 16 publications

References 40 publications

Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent

Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent

Weak and Habitat-Dependent Effects of Nutrient Pollution on Macrofaunal Communities of Southeast Australian Estuaries

Rapid invertebrate responses to macroalgal wrack: two novel field experiments on intertidal mudflats in Southern Australia

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