Search

As a consequence of anthropogenic activities and climate change, accelerated terrestrial sediment runoff is causing the gradual mudification of soft sediment estuarine habitats worldwide. Increased sediment mud content (< 63 µm) has been recognised to alter seagrass morphology and cause declines in primary production in unvegetated habitats. However, the effect of increased mud content on primary production in seagrass meadows remains largely unknown. To address this, primary production in intertidal seagrass meadows (Zostera muelleri) and adjacent unvegetated habitats was measured in situ using benthic incubation chambers across an existing sedimentary gradient (nine sites spanning 5–33% mud content). An additional two unvegetated mudflat sites (39–49% mud content) were also sampled to expand the gradient. Seagrass net (NPP) and gross primary production (GPP) was greater than in the adjacent unvegetated habitat and did not vary with mud content, even after standardising GPP by photosynthesising biomass (i.e. photosynthetic efficiency). In contrast, in the adjacent unvegetated habitat, photosynthetic efficiency declined with increasing mud content. Inclusion of the additional mudflat sites negatively impacted NPP, GPP, and photosynthetic efficiency in the unvegetated habitat. Thus, while primary production in seagrass meadows may have some resilience to future increases in mud content (up to ~33%), further degradation and loss of seagrass habitats could result in the expansion of unvegetated habitats and ultimately lead to production losses, likely to be most acute in areas with high mud content (≥ 39%). [ABSTRACT FROM AUTHOR]

Antarctic marine ecosystems are largely thought to be among the planet's least impacted, yet habitats adjacent to research stations can be heavily polluted. Despite long-term monitoring and remediation being high priorities for international environmental protection, the ecological responses to contaminants and stressors remains poorly characterised, limiting our ability to manage and reduce human impacts. This study compares epifaunal community composition at two sites close to Scott Base with a reference site further away. We couple these data with environmental characteristics, including current data, sediment properties, and contaminant concentrations within the sediment and in the tissues of two epifaunal species, both from this survey and those previously reported. Previously high concentrations of polychlorinated biphenyls and polyaromatic hydrocarbons are now undetectable and concentrations of heavy metals were mostly similar or reduced compared to previous data from 2002. High within-site variance suggests localised contamination footprints from being situated within a deposition zone and/or from the erosion of anthropogenic debris. Despite the persistence of some metals (arsenic, copper and lead) at one site, our study revealed high biodiversity at all three sites (22–28 taxa per 0.25 m2). Benthic community structure was influenced by a combination of factors, including sea ice characteristics, sediment type and habitat complexity. Overall, our study clearly highlights the influence of human activities on the benthos in adjacent marine habitats. The established monitoring protocols coupling diver and remote sampling will enable regular monitoring, filling a critical need for time-series data in order to detect long-term trends and interactions with climate drivers. [ABSTRACT FROM AUTHOR]

Macrobenthic traits, for example feeding mode, life history, morphology, are increasingly used for determining responses of macrobenthic fauna to environmental change and influences on ecosystem functioning. Yet, trait information is scarce or non-existent in several parts of the world, such as New Zealand. This deficit makes collecting trait data a difficult and time-consuming task, limiting its potential use in trait-based assessments. Here, we present the New Zealand Trait Database (NZTD) for marine benthic invertebrates, the first comprehensive assessment of macrobenthic traits in New Zealand. The NZTD provides trait information for more than 700 macrobenthic taxa, categorised by 18 traits and 77 trait modalities. The NZTD includes five freely downloadable datasets, (1) the macrobenthic trait dataset, with outcomes from a fuzzy coding procedure, (2) the trait source information, (3) the references by taxa, (4) the full references list, and (5) the full taxa list used in the NZTD. Establishing the NZTD closes the trait knowledge gap in New Zealand and facilitates future research applying trait-based approaches to New Zealand's coastal macrofauna. [ABSTRACT FROM AUTHOR]

There is substantial evidence that biodiversity underpins ecosystem functioning, but it is unclear how these relationships change with multiple stressors in complex real-world settings. Coastal zones are affected by numerous stressors (for example, sediment input and nutrient runoff from land) and the cumulative effects of these stressors may result in pronounced and unexpected changes in the functioning of ecosystems. To investigate the cumulative effects of turbidity and elevated nutrients on coastal biodiversity-ecosystem functioning relationships, we performed a large-scale field experiment manipulating in situ sediment porewater ammonium concentrations and measured multiple ecosystem functions related to carbon fixation and mineralisation in 15 estuaries with varying levels of turbidity. The results indicated that the benthic macrofauna diversity (species richness, abundance, and functional richness) declined with increased porewater ammonium concentrations and there were clear thresholds in light levels at the seafloor in relation to the biodiversity-ecosystem function relationships. Multifunctionality indices (an integrated index of all measured functions) in moderately turbid and turbid estuaries (daily mean seafloor PAR < 420 µmol m−2 s−1) decreased with the loss of macrofauna biodiversity. Functioning in low-turbidity estuaries (daily mean PAR > 420 µmol m−2 s−1) however remained relatively constant, suggesting that they were more resilient against the nutrient-induced biodiversity loss. Our results demonstrate that ecosystems already stressed by stressors that alter functional performance (turbidity) may be more prone to loss of overall functioning if biodiversity is reduced by another stressor (nutrient enrichment), highlighting the potential snowballing effects of cumulative change. [ABSTRACT FROM AUTHOR]

Similar to other coastal biogenic habitats (e.g. tidal marshes, kelp forests, mangroves and coral reefs), a key function of seagrass meadows is the enhancement of biodiversity. Variability at multiple spatial scales is a driver of biodiversity, but our understanding of the response of macrofauna communities to variability of seagrass meadows is limited. We examined the macrofauna community structure (abundance and biomass) and diversity patterns (α- and β-diversity) across a seascape gradient of eleven seagrass meadows differing in the number, composition and density of plant species. The variability of the macrobenthic communities was regulated by a combination of sedimentary (mainly for the infauna) and macrophyte (mainly for the epifauna) predictors. We demonstrate that the natural occurrence of drifting algae trapped in the aboveground complexity of the meadows benefits seagrass macrofauna. Seagrass-associated macrofauna showed a clear increase in abundance and α-diversity metrics with increasing habitat complexity attributes (i.e. shoot density, plant biomass and canopy height). Furthermore, partitioning of β-diversity (i.e. the variation of species composition between sites) implied the replacement of some species by others between sites (i.e. spatial turnover) instead of a process of species loss (or gain) from site to site (i.e. nestedness). Therefore, the enhancement of macrofauna diversity across an increasing gradient of seagrass complexity, and the dominance of the turnover component suggest that devoting conservation efforts on many different types of meadows, including the less diverse, should be a priority for coastal habitat-management. [ABSTRACT FROM AUTHOR]

To cope with increasing nitrogen loading to estuarine systems, the demand for removal via denitrification is rising. Understanding how the connections between biogeochemistry and ecology regulate denitrification rates along gradients of nutrient and sediment loading is necessary to predict ecosystem function. Previous studies have shown that denitrification rates are typically highest in muddy, nutrient-rich sediments and decrease in sandy, nutrient-poor sites. Denitrification rates were measured at four subtidal sites positioned from the upper to lower estuary. Site 1 was closest to the primary riverine nutrient supply with the highest suspended sediment and benthic mud content that decreased with distance downstream. Contrary to expectations, denitrification rates were lowest at the most upstream site (22.35 ± 13.34 μmol N2 m−2 h−1) and higher downstream (57.84 ± 5.72 μmol N2 m−2 h−1). While respiration, primary production, and sediment characteristics affected net denitrification rates and efficiency, results indicated that macrofaunal abundance (Site 1, 60.8 ± 7.3 individuals/core; Sites 2–4, 177.7 ± 10.8 individuals/core), primarily tube-dwelling polychaetes (Site 1, 0.5 ± 0.5 individuals/core; sites 2–4, 122.5 ± 8.0 individuals/core), played an important role. Their influence was highest in muddier sediments (median grain size < 85 μm) where an increase in pseudopolydorid abundance (0.5 ± 0.5 to 149.5 ± 13.4 individuals per core) resulted in a ~ 3-fold rise in denitrification rate (22.3 ± 13.3 to 62.24 ± 11.1 μmol N2 m−2 h−1). The linkage between macrofauna and denitrification demonstrates their role in maintaining ecosystem function and bolstering resilience in sites affected by sediment and nutrient pollution. [ABSTRACT FROM AUTHOR]

The need for sound baseline information about community structure and composition against which changes can be detected and quantified is a well-recognised priority in Antarctica. Here, the collection of such data is challenging, especially at sea, where long-term monitoring is usually logistically feasible only in the proximity of permanent research stations. In recent years, underwater photogrammetry has emerged as a non-destructive and low-cost method for high-resolution topographic reconstruction. We decided to apply this technique to videos, recorded during standard SCUBA surveys of Antarctic benthos in Tethys Bay (Ross Sea, Antarctica) in 2006 and 2015 and originally not meant for photogrammetry. Our aim was to assess the validity and utility of the photogrammetric method to describe benthic communities from the perspective of long-term monitoring. For this purpose, two of the transects surveyed in 2015 were revisited in 2017. Videos were processed with photogrammetric procedures to obtain 3D models of the seafloor and inhabiting organisms. Overall, a total of six 20 m-long transects, corresponding to a total area of ~ 200 m2 of seafloor were analysed. Accuracy of the resulting models, expressed in terms of Length Measurement Error (LME), was 1.9 mm on average. The 2017 transects showed marked differences in some species, such as a 25–49% increase in the number of sea urchins Sterechinus neumayeri (Meissner, 1900) and the complete disappearance of some sponges Mycale (Oxymycale) acerata Kirkpatrick, 1907. Our analyses confirm the efficacy of photogrammetry for monitoring programmes, including their value for the re-analysis of legacy video footage. [ABSTRACT FROM AUTHOR]

As coastal catchment land use intensifies, estuaries receive increased nutrient and sediment loads, resulting in habitats that are dominated by muddy organic-rich sediments. Increased mud (i.e. silt-clay (particles < 63 μm)) content has been associated with negative effects on soft sediment biodiversity and ecosystem functioning, but the simultaneous impact of nutrient enrichment on ecosystem response is unclear. Nutrient recycling and denitrification in estuarine soft sediments represent important ecosystem functions regenerating nutrients for primary producers and regulating the ability to remove excess terrestrially derived nitrogen. To test the effect of sedimentary environment on ecosystem resilience to nutrient perturbation, we experimentally enriched sediments with slow release fertiliser across an intertidal sedimentary gradient (0-24% mud content). The enrichment successfully elevated pore water ammonium concentrations (median 36 × control) to levels representative of enriched estuaries. Findings show that the sedimentary environment can influence ecosystem function response to nutrient stress. In particular, denitrification enzyme activity was suppressed by nutrient enrichment, but the effect was greater as sediment mud content increased. Furthermore, compared with sandy sediments, sediments with high mud content may restrict nutrient processing (release, uptake or transformation of organic nutrients by the benthos) facilitating ecosystem shifts toward eutrophication. These results show the value of investigating the impacts of stressors in different environmental settings and demonstrate that land use practices that increase the proportion of muddy habitats in estuaries may reduce denitrification which in turn may reduce ecosystem resilience to eutrophication. [ABSTRACT FROM AUTHOR]

The degradation of ecosystems is often associated with losses of large organisms and the concomitant losses of the ecological functions they mediate. Conversely, the resilience of ecosystems to stress is strongly influenced by faunal communities and their impacts on processes. Denitrification in coastal sediments is a process that may provide ecosystem resilience to eutrophication by removing excess bioavailable nitrogen. Here, we conducted a large-scale field experiment to test the effect of macrofaunal community composition on denitrification in response to two levels of nutrient enrichment at 28 sites across a biologically heterogeneous sandflat. After 7 weeks of enrichment, we measured denitrification enzyme activity (DEA) along with benthic macrofaunal community composition and environmental variables. We normalised treatment site specific DEA values by those in ambient sediments (DEA) to reveal the underlying response across the heterogeneous landscape. Nutrient enrichment caused reductions in DEA as well as functional changes in the community; these were both more pronounced under the highest level of nutrient loading (on average DEA was reduced by 34%). The degree of suppression of DEA following moderate nitrogen loading was mitigated by a key bioturbating species, but following high nitrogen loading (which reduced the key species density) the abundance and diversity of other nutrient processing species were the most important factors alleviating negative effects. This study provides a prime example of the context-dependent role of biodiversity in maintaining ecosystem functioning, underlining that different elements of biodiversity can become important as stress levels increase. Our results emphasise that management and conservation strategies require a real-world understanding of the community attributes that facilitate nutrient processing and maintain resilience in coastal ecosystems. [ABSTRACT FROM AUTHOR]

The density, spatial structure and functional roles of macrofaunal and microphytobenthic (MPB) communities change across sedimentary gradients. Grazing by macrofauna can impose considerable top-down control on MPB biomass at the scale of the animal's feeding ambit (cm scale), yet how relationships between deposit feeders and MPB scale up across such transitional environments (10's m scale) is poorly understood. We determined the relationship between sediment chlorophyll- a concentration (a proxy of MPB biomass), distance to feeding traces (a proxy of recent deposit feeding activity) made by the tellinid bivalve Macomona liliana (at cm scale) and macrofaunal densities (at 10's m scale) across a sediment mud content gradient. Correlative relationships, estimated by generalised least-squares regression, between recent deposit feeding activity and MPB biomass were scale dependent and significant only at the site (10's m) scale. MPB biomass declined by 28 % as coverage of feeding traces increased from 2 to 28 %, with feeding trace area contributing significantly to variation in chlorophyll- a (std. coefficient = −0.24, p = 0.01). However, the interaction term between the density of the suspension-feeding clam Austrovenus stutchburyi and sediment mud content explained a larger amount of the variability (std. coefficient = 0.72, p < 0.001). Our results demonstrate that significant effects on MPB biomass can emerge across large, spatially heterogeneous areas of tidal flat, despite appearing stochastic at small scales. They also highlight the need to consider interactions between MPB and macrofauna across abiotic gradients and the potential roles of non-deposit feeding taxa. [ABSTRACT FROM AUTHOR]

The Portunid crab Charybdis japonica was first found in Waitemata Harbour, New Zealand, in 2000. It has established breeding populations and has been spreading, yet information on its dietary preferences in New Zealand are unknown. We conducted field caging experiments to elucidate prey choices and potential impacts of Charybdis on benthic communities. We tested the hypothesis that Charybdis would reduce the previously demonstrated positive influence of native pinnid bivalves, Atrina zelandica, on the abundance and richness of surrounding soft-sediment macrofauna. Adult male Charybdis were introduced to cages with and without Atrina that included soft-sediment macrofaunal communities of ambient composition and abundance. After leaving the crabs to feed overnight, changes in community structure (relative to sediments without crabs) were determined by coring the sediment and analysing the resident macrofauna. Prey choices were verified by extracting taxa from the stomachs of crabs collected from the cages in which they had been feeding. The abundance of large taxa including burrowing urchins, bivalves and native crabs was lower in the presence of Charybdis compared to areas without this invader. The stomach contents of Charybdis were dominated by these same three taxa, constituting 85 % of the prey abundance when using stomach fullness as a weighting factor. Our hypothesis was supported with the greatest net losses occurring in cages with Charybdis and Atrina. Reduction in the abundance of Echinocardium cordatum by Charybdis could have cascading ecological effects, as these urchins play a critical role in benthic soft-sediment ecosystems in New Zealand via bioturbation and biogenic disturbance. [ABSTRACT FROM AUTHOR]

The world's oceans are changing, and dramatic shifts have been documented in the Southern Ocean. The consequences of these shifts to coastal benthic organisms are difficult to predict at present, as ocean warming may increase primary production and food resources for benthic consumers, whilst OA may have negative impacts that differentially affect various species and life stages. A model was developed to investigate how different scenarios of change may influence population size of the Antarctic bivalve Laternula elliptica. The model describes potential implications of both pH and temperature change on survivorship and reproductive output of a population of this bivalve species in McMurdo Sound, Ross Sea. Implications of increases and decreases in mortality rate across different life stages of the population (early, mid and late) were assessed. Additionally, effects on energetic resource partitioning and dictating reproductive potential (RP) were also investigated. Significant declines in RP, due to increased basal metabolic demand, were associated with even relatively small changes in temperature and pH, resulting in populations declining to 25 % of the starting equilibrium density within 60 years. As L. elliptica is a pivotal species to the functionality of the Antarctic coastal benthic ecosystem, wide spread repercussions are expected if populations are impacted as the model predicts. Although further model development is required to explore the ecosystem implications of the population decline described in this paper, this work allows a better understanding of the consequences of change as soon as data on the direction and magnitude of the changes affecting Antarctic seas become available. [ABSTRACT FROM AUTHOR]

The input of terrestrial silt and clay (hereafter mud) into coastal environments can alter sediment grain size distribution affecting the structure and functioning of benthic communities. The relationship between sediment mud content and macrofaunal community structure has been well documented, but not the effects on ecosystem function. In 143 plots from the mid-intertidal sites in 9 estuaries, we measured sediment properties, macrofaunal community composition and fluxes of O and NH across the sediment-water interface to derive process-based measures of ecosystem function across the sand-mud gradient. We observed reductions in measures of macrofaunal diversity and decreases in the maximum density of key bioturbating bivalves ( Austrovenus stutchburyi and Macomona liliana) with increased mud content. Concurrently, the maximum rates of sediment oxygen consumption (SOC), NH efflux (NH) and biomass standardized gross primary production (GPP) also decreased with increasing mud content. Environmental predictors explained 34-39% ( P = 0.005-0.01) of the total variation in ecosystem function in distance-based linear models. After partitioning out the effect of mud, A. stutchburyi abundance was positively correlated and explained 25 and 23% ( P = 0.0001) of the variation of SOC and NH, respectively. Also, mud content (negatively correlated) and temperature (positively correlated) explained 26% of variability in GPP ( P = 0.0001). Our results highlight the importance of increased mud content and the associated reduction in the abundance of strongly interacting key species on the loss of ecosystem function in intertidal sand flats. [ABSTRACT FROM AUTHOR]

Antarctic sea ice and the cold waters surrounding the continent are key elements of the global climate system, influencing heat redistribution, oceanic circulation and the absorption of carbon dioxide from the atmosphere. However, the Southern Ocean is predicted to warm by 1-6°C over the next century, altering sea ice extent, thickness and permanence. To better understand the connections between coastal sea ice conditions and the functioning of Antarctica's unique marine benthic ecosystems, we performed manipulative experiments on the seafloor at two southwestern Ross Sea sites with contrasting sea ice conditions. Benthic systems at both study sites were net heterotrophic during the study period (early November), with primary production most likely limited by light availability rather than nutrients. There was five times more fresh algal detrital material in benthic sediments at the site with the thinner, snow-free, annually formed sea ice, relative to the site with thicker, multiyear sea ice. This elevated quantity and quality of algal detrital matter corresponded with a significantly greater rate of sediment oxygen utilization by the benthos and an altered pathway of nitrogen regeneration (tighter coupling between nitrification and denitrification). Large benthic animals (brittle stars, Ophionotus victoriae) enhanced the efflux of dissolved inorganic nutrients from the sediment to the water column and played a greater role in nutrient regeneration at the site with more food. Although changes in sea ice characteristics in the Western Ross Sea are difficult to predict at present, large benthic organisms can be expected to have an expanded role in mediating the effects of elevated coastal productivity and detritus supply on ecosystem dynamics in this part of Antarctica. [ABSTRACT FROM AUTHOR]

Species are often grouped according to their biological or functional traits to better understand their contribution to ecosystem functioning. However, it is becoming clear that a single species can perform different roles in different habitats. Austrohelice crassa, a burrow-building mud crab shifts its primary bioturbational role to that of a vertical mixer in non-cohesive sediments as frequent burrow collapse greatly enhances sediment reworking. We conducted in situ crab density manipulations in two sediment environments (a non-cohesive sand and a cohesive muddy-sand) to examine if the context-specific functional roles were linked to changes in solute fluxes across the sediment-water interface. Across both habitats, we show that A. crassa regulated nutrient cycling, creating strong density driven effects on solute exchanges. Increasing crab density increased sediment O demand and the flux of NH from the sediment, indicating much of the response was physiologically driven. Clear interactions between A. crassa and microphytobenthos were also detected in both habitats. Despite lowering microphyte standing stock through deposit feeding, A. crassa increased benthic primary production per unit of chlorophyll a. Our experiment also revealed important context-specific differences, most notably for NH fluxes, which were higher where burrows and their associated microbial communities were most stable (muddy-sand). This study highlights the need to integrate interactions between organism behavior and habitat type into functional group studies to broaden conceptual frameworks and avoid oversimplification of highly complex organism-sediment interactions. [ABSTRACT FROM AUTHOR]

The threat of homogenisation to biodiversity is generally considered to occur at broad scales or in response to high-intensity impacts. Therefore, most biodiversity studies estimate local average or total species richness rather than local heterogeneity. Here we consider the potential for relative shifts between these different aspects of biodiversity at small spatial scales to be an early warning signal for biodiversity loss. In response to chronic, very low-level pollution, we observed a disjunctive response with gamma diversity (total species richness) and beta diversity (heterogeneity) decreasing while alpha diversity (average species richness) was still increasing. Homogenisation may, therefore, affect biodiversity through thresholds that alter the relationship between the average species richness and its heterogeneity, leading to the potential for regime shifts. Our stressor also had a strong negative effect on rare species, meaning that the purported importance of rare species as ''insurance'' in the face of environmental change may be overstated. [ABSTRACT FROM AUTHOR]

Predicting the consequences of species loss is critically important, given present threats to biological diversity such as habitat destruction, overharvesting and climate change. Several empirical studies have reported decreased ecosystem performance (for example, primary productivity) coincident with decreased bio-diversity, although the relative influence of biotic effects and confounding abiotic factors has been vigorously debated. Whereas several investigations focused on single trophic levels (for example, grassland plants), studies of whole systems have revealed multiple layers of feedbacks, hidden drivers and emergent properties, making the consequences of species loss more difficult to predict. Here we report functionally important organisms and considerable biocomplexity in a sedimentary seafloor habitat, one of Earth's most widespread ecosystems. Experimental field measurements demonstrate how the abundance of spatangoid urchins—infaunal (in seafloor sediment) grazers / deposit feeders—is positively related to primary production, as their activities change nutrient fluxes and improve conditions for production by microphytobenthos (sedimentary microbes and unicellular algae). Declines of spatangoid urchins after trawling are well documented, and our research linking these bioturbators to important benthic-pelagic fluxes high- lights potential ramifications for productivity in coastal oceans. [ABSTRACT FROM AUTHOR]

The exotic Asian shore crab, Hemigrapsus sanguineus, was recently introduced to the northeastern coast of North America and during the 1990's breeding populations were established throughout southern New England. In 1997–1998, ecological studies of several co-occurring brachyuran crabs were conducted and in native (Tanabe Bay, Japan) and invaded (Long Island Sound, USA) habitats of H. sanguineus. Standardized comparisons of H. sanguineus were made between the 2 habitats using data on crab sizes, utilization of space, and food habits. Results revealed that (1) the resource use of H. sanguineus was quite different from that of other resident species in its invaded habitat, and (2) there were no substantial changes in resource utilization by H. sanguineus after it became established in the invaded habitat (relative to native Tanabe Bay). Differing patterns of resource use by H. sanguineus and other crabs in the invaded habitat, the lack of restriction in resource use by H. sanguineus following its introduction, and the climatological and physical similarities between native and invaded regions likely contributed to the successful invasion of H. sanguineus into rocky intertidal habitats in southern New England. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 concentrations are contributing to ocean acidification (reduced seawater pH and carbonate concentrations), with potentially major ramifications for marine ecosystems and their functioning. Using a novel in situ experiment we examined impacts of reduced seawater pH on Antarctic sea ice-associated microalgal communities, key primary producers and contributors to food webs. pH levels projected for the following decades-to-end of century (7.86, 7.75, 7.61), and ambient levels (7.99), were maintained for 15 d in under-ice incubation chambers. Light, temperature and dissolved oxygen within the chambers were logged to track diurnal variation, with pH, O2, salinity and nutrients assessed daily. Uptake of CO2 occurred in all treatments, with pH levels significantly elevated in the two extreme treatments. At the lowest pH, despite the utilisation of CO2 by the productive microalgae, pH did not return to ambient levels and carbonate saturation states remained low; a potential concern for organisms utilising this under-ice habitat. However, microalgal community biomass and composition were not significantly affected and only modest productivity increases were noted, suggesting subtle or slightly positive effects on under-ice algae. This in situ information enables assessment of the influence of future ocean acidification on under-ice community characteristics in a key coastal Antarctic habitat. [ABSTRACT FROM AUTHOR]

Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass sediment chlorophyll a content (Chla) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings. [ABSTRACT FROM AUTHOR]