Matching the outcome of small-scale density manipulation experiments with larger scale patterns

Thrush, Simon F.; Cummings, Vonda J.; Dayton, Paul K.; Ford, Richard B.; Grant, John A.; Hewitt, Judi E.; Hines, Anson H.; Lawrie, S.; Pridmore, R. D.; Legendre, Pierre; McArdle, Brian H.; Schneider, David C.; Turner, Stephanie; Whitlatch, Robert B.; Wilkinson, M. R.

doi:10.1016/s0022-0981(97)00094-4

Cited by 91 publications

(46 citation statements)

References 21 publications

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“…This scale of variability reflects real-world complexity and should be incorporated into future experiments in order to increase generality and application of conclusions. The way to achieve this is through well replicated gradient designs that consider co-variables (Eberhardt and Thomas, 1991;Ellis and Schneider, 2008;Hewitt et al, 2007;Thrush et al, 1997). Many of the reviewed nutrient enrichment studies had research questions that required categorical type designs; the majority (68%) used only a single fertiliser application rate, the average number of treatment replicates was just five, and more than half the studies (57%) were conducted across spatial scales much less than 1 km (Appendix 1).…”

Section: Tablementioning

confidence: 99%

In situ soft sediment nutrient enrichment: A unified approach to eutrophication field experiments

Douglas

Pilditch

Hines

et al. 2016

Marine Pollution Bulletin

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Adding fertiliser to sediments is an established way of studying the effects of eutrophication but a lack of consistent methodology, reporting on enrichment levels, or guidance on application rates precludes rigorous synthesis and meta-analysis. We developed a simple enrichment technique then applied it to 28 sites across an intertidal sandflat. Fertiliser application rates of 150 and 600 g N m −2 resulted in pore water ammonium concentrations respectively 1-110 and 4-580 × ambient, with greater elevations observed in deeper (5-7 cm) than surface (0-2 cm) sediments. These enrichment levels were similar to eutrophic estuaries and were maintained for at least seven weeks. The high between-site variability could be partially explained by the sedimentary environment and macrofaunal community (42%), but only at the high application rate. We suggest future enrichment studies should be conducted in situ across large environmental gradients to incorporate real world complexity and increase generality of conclusions.

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Section: Tablementioning

confidence: 99%

In situ soft sediment nutrient enrichment: A unified approach to eutrophication field experiments

Douglas

Pilditch

Hines

et al. 2016

Marine Pollution Bulletin

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“…This landscape could represent a stress or disturbance gradient or spatial structure in the density or size of key species or diversity within a functional group. This design and, more generally, the construction of gradients facilitate the use of co-variables to tease apart the effects of different factors on experimental processes and multi-scale analysis (Thrush et al 1997;Thrush et al 2000;Hewitt et al 2007). …”

Section: Identifying Thresholds and Designing Studies To Improve Our mentioning

confidence: 99%

Forecasting the limits of resilience: integrating empirical research with theory

et al. 2009

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Despite the increasing evidence of drastic and profound changes in many ecosystems, often referred to as regime shifts, we have little ability to understand the processes that provide insurance against such change (resilience). Modelling studies have suggested that increased variance may foreshadow a regime shift, but this requires long-term data and knowledge of the functional links between key processes. Field-based research and ground-truthing is an essential part of the heuristic that marries theoretical and empirical research, but experimental studies of resilience are lagging behind theory, management and policy requirements. Empirically, ecological resilience must be understood in terms of community dynamics and the potential for small shifts in environmental forcing to break the feedbacks that support resilience. Here, we integrate recent theory and empirical data to identify ways we might define and understand potential thresholds in the resilience of nature, and thus the potential for regime shifts, by focusing on the roles of strong and weak interactions, linkages in meta-communities, and positive feedbacks between these and environmental drivers. The challenge to theoretical and field ecologists is to make the shift from hindsight to a more predictive science that is able to assist in the implementation of ecosystem-based management.

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“…Secondly, operational measures of habitat heterogeneity, complexity and structure are needed that include the quantification of a variety of different elements. Many studies categorise habitats into simple or structured based on the presence of a single feature rather than treating these as landscape elements (for examples of the latter see Robbins & Bell 1994, Irlandi et al 1995, Thrush et al 1997a). The problem of overgeneralizing results is especially relevant to any general consideration of biodiversity (Huston 1997).…”

Section: Introductionmentioning

confidence: 99%

Fishing disturbance and marine biodiversity: the role of habitat structure in simple soft-sediment systems

Thrush¹,

Hewitt²,

Funnell³

et al. 2001

Mar. Ecol. Prog. Ser.

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Broad-scale anthropogenic disturbances that reduce the density of epifauna and homogenise surficial sediments can have important consequences for seafloor biodiversity. We investigated the habitat structure and macrofaunal diversity of relatively simple soft-sediment habitats over a number of spatial scales (cm to km) to identify the role of habitat structure in influencing macrobenthic diversity and to assess the validity of using habitat structure as a surrogate measure for biodiversity. We sampled 10 locations with differences in habitat structure using a sampling design that nested macrobenthic core samples within videoed transects of the seafloor. This allowed us to determine relationships between observable habitat structure and macrobenthic diversity at a number of spatial scales. We characterised elements of habitat structure based on direct counts of surficial sediment characteristics and the presence of other immobile features, many of which were biogenic in origin. We also used multivariate measures (the relative multivariate dispersion, the mean and range of the Bray-Curtis dissimilarity along the transects) to characterise habitat structure at the transect scale. We developed regression models based on measures of habitat structure that explained 74 to 86% of the variance in macrobenthic diversity. This result suggests that removal of habitat structure in relatively low-structure soft-sediment systems will significantly decrease their biodiversity, and consequently that of the wider marine ecosystem.

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Matching the outcome of small-scale density manipulation experiments with larger scale patterns

Cited by 91 publications

References 21 publications

In situ soft sediment nutrient enrichment: A unified approach to eutrophication field experiments

In situ soft sediment nutrient enrichment: A unified approach to eutrophication field experiments

Forecasting the limits of resilience: integrating empirical research with theory

Fishing disturbance and marine biodiversity: the role of habitat structure in simple soft-sediment systems

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