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Wetland sediment inhabited by a midge larva (Diptera: Chironomidae) in its U-shaped burrow, and oligochaete worms (Oligochaeta: Tubificinae) feeding head-down in sediments. Oligochaete consumption of organic particles from deeper sediment layers and subsequent translocation and accumulation of particles at the sediment–water interface causes a downward movement of sediment, the rate of which is determined by oligochaete size and density. Particles move downward until they reach the zone of oligochaete feeding, where they are ingested and transported rapidly above the sediment–water interface. This process, which may be repeated several times until particles pass below the zone of oligochaete feeding, results in enhanced transport and “conveyor belt” cycling of organic particles between oxic and anoxic layers of sediments. Meanwhile, midge larvae ventilate their U-shaped burrows in shallower layers of sediment, alternately drawing nitrate and oxygen as well as organic particles into burrows, thereby enhancing oxygenation of sediments, nitrification, and denitrification, and the production of N2 and N2O in shallow sediments.
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One of the goals of urban ecology is to link community structure to ecosystem function in urban habitats. Pollution-tolerant wetland invertebrates have been shown to enhance greenhouse gas (GHG) flux in controlled laboratory experiments, suggesting that they may influence urban wetland roles as sources or sinks of GHG. However, it is unclear if the...
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Context 1
... synergistic or antagonistic effects when present in combination, due to their different modes of bioturbation. For example, midge larvae bioirrigate sediments through construction and ventilation of U-shaped tubes, but oligochaetes redistribute sediments to a greater degree and at greater depths than midge larvae, via "conveyor-belt feeding" ( Fig. 1; Lagauz ere et al. 2009). Furthermore, given the variable environmental conditions present in field settings, the degree to which invertebrate effects can be detected relative to other drivers of GHG flux amidst the "noise" in urban environments requires further ...Context 2
... d 13 N (&). A few specimens were removed from each core, allowed to clear their guts for 24 h, and dried at 60°C for 48 h. These were weighed to the nearest lg, and then analyzed for C org and N org content and stable isotope ratios (d 13 C, d 13 N) using the methods already described. Data are provided in the supporting information (Appendix S1: Fig. ...Context 3
... communities in all sites were dominated by oligochaetes and midge larvae. Oligochaetes accounted for ~82% AE 10% and 60% AE 20% (mean AE 95% CI) of average total invertebrate density in treatment wetlands and gc ponds, respectively (Fig. 3, Appendix S1: Table S3). Tubificinae (family Naididae) was the most abundant subfamily of oligochaetes, accounting for 78% AE 9% and 85% AE 14% of all oligochaetes encountered in treatment wetlands and gc ponds (Appendix S1: Table S4). Oligochaete density did not differ significantly between treatment wetlands and gc ponds (F 1,22 = 2.15, P = ...Context 4
... that of the top-performing CO 2 flux model, which included temperature, density of all large oligochaetes and chironomids, and sediment C org content (Table 1, Fig. 4). The improvement of CH 4 flux prediction with the inclusion of benthic invertebrate density in models was even greater, with the RMSE of the best model excluding invertebrates being 29% higher (poorer predictive ability) than that of the top-performing CH 4 flux model, which included temperature, density of large oligochaetes, and sediment C org content (Table 1, Fig. 5). ...Context 5
... the case of N 2 O flux, inclusion of invertebrate density did not substantially improve the predictive ability of models. All of the highest-ranked models (Δi < 2) models included temperature, nitrate + nitrite (NO X ), oxygen % saturation (DO) and an interaction term (NO X 9 DO), but the RMSE of models excluding or including invertebrates were similar (within 4.5%) in predictive ability (Table 1, Fig. 6). ...Context 6
... of dissolved O 2 in water column; NO X 9 DO%, interaction between NO X and DO%. (Figs. 4, 5) is likely due to several factors, including (1) enhanced upward gas transport and diffusion through invertebrate burrows, (2) rapid cycling of organic matter between oxic and anoxic layers of sediment, due to conveyor-belt feeding by oligochaetes (Fig. 1), and (3) simultaneous enhancement of oxygenation and aerobic microbial respiration in upper sediment layers due to increased porosity, and enhanced anoxia (and therefore methane production) in lower layers of sediment due to microbial and oligochaete respiration. While it has been suggested that invertebrates grazing on methanotrophic ...Context 7
... that invertebrates grazing on methanotrophic bacteria have the potential to enhance CH 4 fluxes in aquatic ecosystems ( Kankaala et al. 2007), this seems unlikely in the current study. The d 13 C values as low as À38.4 & suggest the possibility that midge larvae may have consumed methanotrophic bacteria at a few of our study sites (Appendix S1: Fig. S1; Jones et al. 2008), but this was rare and not observed for oligochaetes, which were the only taxa with densities significantly correlated to CH 4 ...Context 8
... laboratory analyses at Monash University, Benedikt Fest and Steve Livesley assisted with greenhouse gas analysis at the University of Melbourne, and Jennifer Gonzalez and Guillermo Mendoza assisted with sorting and identification of preserved invertebrates at Scripps Institution of Oceanography. Meredith K. Meyers assisted with the creation of Fig. 1. We also thank Teresa Mackintosh, and William Steele from Melbourne Water, who fostered discussion and facilitated access to constructed wetland sites in Australia; and Dave Mason, Michael Freeman, Robert Sim, Chris Allen, and Stuart Cooper who generously provided access and resources to facilitate sampling ponds at their golf clubs ...Similar publications
The invasive golden mussel Limnoperna fortunei is known to strongly affect benthic communities in South American freshwaters, but the evolution of these effects after the early invasion stages is poorly understood. Using predator exclusion (covered with 15- and 40-mm meshes) and inclusion (unprotected) substrates, we investigated the interaction be...
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... Nogaro and Burgin (2014) showed that CH 4 release does not significantly increase along with tubificid-oligochaete abundance in organic-rich estuarine sediments. Opposite is the situation of urban wetlands, where CH 4 fluxes are strongly correlated with tubificid abundance (Mehring et al. 2017). Experimental work suggested that Baltic Sea bivalves may induce a seven-to ten-fold increase of CH 4 efflux compared to sediment without macrofauna (Bonaglia et al. 2017). ...
Sediment macrofauna play a vital role in sustaining aquatic food webs and biogeochemical cycles. Previous research demonstrated that bioturbation indirectly affects methane (CH 4 ) dynamics through mobilization of porewater and alteration of microbial processes in the surrounding sediment. However, little is known on the direct contribution of macrofauna holobionts (the assemblage of invertebrate host and associated microbiome) to biogeochemical fluxes. Here, we investigated how 19 taxa of macrofauna holobionts, from different estuarine habitats spanning 40° to 63° latitude, directly contribute to CH 4 fluxes. Deep burrowing infauna and deposit feeders were responsible for the highest CH 4 production, whereas epifauna and filter feeders promoted oxidative CH 4 consumption. Among the different environmental parameters, salinity was inversely correlated with CH 4 production by macrofauna holobionts, with the process suppressed at high salinity (≥ 33). This study provides empirical evidence on how functional traits and environmental factors influence sediment invertebrates' contribution to CH 4 fluxes.
... Higher density of benthic organism at low concentrations of NH 4 + and NO 3 − in low temperature strongly enhanced N 2 O flux; however, higher temperature promotes CO 2 and CH 4 fluxes from sediment bed (Datta et al. 2009). Bioturbation activity promotes redox oscillation at SWI which creates intermediate redox potential, a favorable environment for N 2 O emission (Mehring et al. 2017). Maximum amount of N 2 O emitted either from the burrow wall of the sediment or directly from the anaerobic media of gut of burrowing organisms . ...
Bioturbation is recognized as a deterministic process that sustains the physicochemical properties of the freshwater ecosystem. Irrigation, ventilation, and particle reworking activities made by biotic components on sediment beds influence the flow of nutrients and transport of particles in the sediment–water interface. Thus, the biogenic disturbances in sediment are acknowledged as pivotal mechanism nutrient cycling in the aquatic system. The macroinvertebrates of diverse taxonomic identity qualify as potent bioturbators due to their abundance and activities in the freshwater. Of particular relevance are the bioturbation activities by the sediment-dwelling biota, which introduce changes in both sediment and water profile. Multiple outcomes of the macroinvertebrate-mediated bioturbation are recognized in the form of modified sediment architecture, changed redox potential in the sediment–water interface, and elicited nutrient fluxes. The physical movement and physiological activities of benthic macroinvertebrates influence organic deposition in sediment and remobilize sediment-bound pollutants and heavy metals, as well as community composition of microbes. As ecosystem engineers, the benthic macroinvertebrates execute multiple functional roles through bioturbation that facilitate maintaining the freshwater as self-sustaining and self-stabilizing system.
Graphical abstract
The likely consequences of bioturbation on the freshwater ecosystems facilitated by various macroinvertebrates — the ecosystem engineers. Among the macroinvertebrates, varied species of molluscs, insects, and annelids are the key facilitators for the movement of the nutrients and shaping of the sediment of the freshwater ecosystem.
... Cfb. Oligochaetes and midge larvae are the main invertebrate communities in stormwater wetlands [247]. There is homogenization of macroinvertebrate communities across the study wetlands, with some dependency between receiving wetland conditions and the degree of urbanization of the catchment, but other factors may be important too [248]. ...
... Cfb. Large benthic invertebrates increase in average methane and CO 2 flux, so urban wetlands without control may make greater contributions to the total greenhouse gas budget in cities [247]. ...
... Regulation Services: Climate Change and thermal control: Green swales and permeable pavement can act as temperature regulators [28,114], but other SUDS can emit greenhouse gases due to warmer temperatures [53], the benthic invertebrates metabolism [247], or the use of herbicides to remove aquatic vegetation [210]. ...
Urban green infrastructure such as sustainable urban drainage systems are potential providers of ecosystem services. This paper reviews the field studies that empirically verify the potential benefits of SUDS. The cultural, provisioning, supporting, and regulating ecosystem services investigated in real cases have been studied and classified according to climatology (except for the control of urban hydrology, which has been widely corroborated). Although successful cases of runoff decontamination are numerous, there is heterogeneity in the results of the systems beyond those associated with climatic differences. The other ecosystem services have not been as widely studied, giving very variable and even negative results in some cases such as climate change control (in some instances, these techniques can emit greenhouse gases). Installations in temperate climates are, by far, the most studied. These services derive from the biological processes developed in green infrastructure and they depend on climate, so it would be advisable to carry out specific studies that could serve as the basis for a design that optimizes potential ecosystem services, avoiding possible disservices.
... Although this may have been expected from previous studies (Drake et al. 2006;Depkat-Jakob et al. 2012), it was never confirmed. Furthermore, conditions for methane emission generally occur only in selected niches such as invertebrate guts (Šustr and Šimek 2009) and wetland environments (Mehring et al. 2017). We have shown here that this niche can be extended to the castings of R. alatus and could be expected from castings of other earthworm species, particularly compacting species (sensu Blanchart et al. 1997) and those inhabiting wetlands, whose casts will be more water saturated and with limited O 2 . ...
Greenhouse gas emissions (CO2, N2O, CH4) and chemical, physical and microbiological properties (pH, macro and micronutrients, texture, moisture, exchangeable NH4⁺, NO3⁻, total C and N, organic C, microbial biomass C and metabolic coefficient) were monitored in casts of a large, endogeic native Brazilian earthworm species Rhinodrilus alatus and from non-ingested control soil incubated for up to 32 days. Earthworm casts represented a significantly different chemical and microbiological environment, with higher soil moisture, pH, H + Al, exchangeable NH4, Cu, Fe and Mn contents, lower microbial biomass C and higher metabolic quotient (qCO2), but with few differences in CO2, N2O and CH4 emissions compared with non-ingested control soil. Nonetheless, fermenting, methanogenic and nitrate-reducing microbes encountered ideal conditions for sustained anaerobic activity in the clayey, dense and moist castings of R. alatus, maintaining emission of N2O and CH4 and confirming previous results observed using gut contents. The high exchangeable NH4 and H2O contents influenced the oxy-reduction processes, affected GHG emissions and N transformations and modified soil microbial biomass and activity. In addition, selective ingestion concentrates C and N contents in the casts and transformation processes affect the availability of important plant nutrients, topics that deserve further attention, considering the widespread collection of this species for use as fish-bait in Brazil.
... Benthic invertebrates are abundant in mangrove forests and their bioturbation activities are essential to biogeochemical cycles, ultimately influencing the diagenesis of OC within soils (Aller 1982;Kristensen and Alongi 2006;Kristensen et al. 2008). Bioturbation has only recently been considered important for OC dynamics in coastal wetland soils, with growing evidence that large benthic bioturbators may increase or decrease soil carbon stocks (Andreetta et al. 2014;Atwood et al. 2015;Mehring et al. 2017;Thomson et al. 2019). Increased remineralization of soil carbon may occur when bioturbation increases soil oxygen supply, whereas burial of plant detritus into deep anoxic soil layers by benthic fauna may increase OC sequestration (Lee 1998;Kristensen et al. 2008;Andreetta et al. 2014;). ...
... The importance of geomorphology and physical deposition of OC in tidal flats ) is highlighted by the tidal flats in our study sites which had extremely high rates of OC burial and weak correlation with bioturbation potential. Although bioturbation potential was found here to be unrelated to OC burial, bioturbation is key to microbial remineralization of deposited OC and greenhouse gas emissions in wetlands (Mehring et al. 2017;Cameron et al. 2019; Thomson et al. 2019). ...
The potential of Blue Carbon as an integral part of global climate change adaptation and mitigation strategies requires quantification of drivers and rates of organic carbon (OC) burial and storage. However, there is limited recognition of how land use impacts benthic assemblages, their bioturbation potential, and OC burial in mangrove forests and tidal flats. Here we evaluated the effects of mangrove deforestation on benthic bioturbation potential (BPc), sediment accretion rates (SAR), and OC and total nitrogen (TN) burial in mangrove soils and tidal flat sediments from three estuaries in tropical Brazil. SAR based on 210 Pb dating varied significantly among undisturbed estuaries (2.1 to 18.6 mm.yr-1) and the OC and TN burial rates were respectively 46% and 16% higher than global averages. The cleared mangrove sites had a 2-fold lower SAR, 40-fold lower OC burial and over 100-fold lower TN burial when compared to undisturbed forests, revealing the pervasive impacts of land use. Variation in benthic assemblage structure and BPc among sites suggest that the composition and activity of macrofaunal communities may facilitate OC burial in some cases, yet the global extent and significance of bioturbation requires further study. Our work reveals a strong spatial variability in C burial in undisturbed mangrove forests and a decreased capacity of mangroves to accumulate C and sediments due to land use effects.
... These enhanced CH 4 emissions could be due to new CH 4 inputs from wastewater treatment plants (WWTPs) and storm drains (Alshboul et al., 2016;Hu et al., 2017). Alternatively, internal CH 4 production could increase in response to labile C leached from agricultural fields (Borges et al., 2018b), excess nitrogen (N) and phosphorous (P) increasing biological O 2 consumption and triggering suitably anaerobic conditions and/or producing more labile C (Vivanco et al., 2015), or a more fine-grained and C-rich benthos created by erosion and eutrophication, respectively (Mehring et al., 2017;Stanley et al., 2016). It is therefore difficult to transfer the 'black box' type models where eutrophication indicators like chlorophyll (Chla) and nutrient (nitrogen, N and phosphorous, P) concentrations predict CH 4 emissions developed in freshwater lakes (e.g., Beaulieu et al. (2019)) to other systems. ...
... We hypothesised that eutrophication-induced increases in sediment C content would increase CH 4 emissions from the human-impacted estuaries, as found in freshwater systems (Borges et al., 2018c;Mehring et al., 2017;Romeijn et al., 2019). The expectation that sediment C content predicted F CH4(B) was supported by findings at both the habitat (Fig. 4) and whole-system (Fig. 5b) scale, with F CH4(B) greatest in Maroochy and lowest in Brisbane. ...
Coastal waters are known to emit globally significant quantities of CH 4 , a potent greenhouse gas, but the potential of the rapid and ongoing human alterations to coastal areas to alter these emissions remains undefined. Here we addressed this gap by quantifying water-to-air CH 4 fluxes and δ 13 C-CH 4 values in subtropical estuaries at Low (n = 3), Moderate (n = 2), and High (n = 3) levels of human modification (agricultural land use, wastewater discharge), and sediment-to-water CH 4 fluxes from the major benthic habitats in representative Low, Moderate, and High systems. An increase in water-to-air CH 4 fluxes from 9.7 µmol m-2 d-1 (Low) to 28 µmol m-2 d-1 (Moderate) to 47 µmol m-2 d-1 (High) was accompanied by a shift from hydrogenotrophic to acetoclastic production pathways. Unexpectedly, benthic CH 4 production, which ranged from-48 µmol m-2 d-1 to +180 µmol m-2 d-1 between habitats, estuaries, and seasons, was not the primary driver of this shift. Sediments produced more CH 4 (~600%) than emitted from the Low estuary, ~90% of CH 4 emitted from the Moderate estuary, but only 9% of CH 4 emitted from the High estuary. Instead, a combination of wastewater, groundwater, and apparent water column production caused a ~3-fold increase in estuary CH 4 emissions. Our findings indicate that human alterations to the source, rate, and pathways of CH 4 production are driving a net increase in emissions from estuaries, demonstrating a need to redefine how we quantify 'anthropogenic' CH 4 emissions.
... Therefore, DO carried by the downwelling provides the necessary conditions for a rich community to some extent. Macroinvertebrate metabolism consumes organic matter and produces dissolved inorganic carbon (DIC, mainly the greenhouse gas CO 2 ), affecting surface water quality [80,81]. Downwelling was more correlated with HCO 3 − and CO 3 2− than upwelling (Figure 3a,b). ...
... Water temperature in the Weihe River basin adjusted by upwelling or downwelling to be maintained at 16-27 • C, which is close to the temperature (15-25 • C) found by Lou [72], increases the growth rate of Tubificida. Additionally, Tubificidae is a pollution-tolerant oligochaete that can tolerate the adverse effects of temperature fluctuations and pollutants caused by different exchanges [81]. Therefore, Tubificidae can persist in both upwelling and downwelling sites, promoting the dominance of the burrower in the community (Figure 3a). ...
The effect of hyporheic exchange on macroinvertebrates is a significant topic in ecohydraulics. A field study was conducted during May and June 2017 to investigate the impacts of magnitude and patterns of hyporheic exchange on the sediment macroinvertebrate community in the Weihe River basin. The results demonstrate that upwelling flows cause resuspension of riverbed sediment, increasing the proportion of swimmer groups (such as Baetidae) in the macroinvertebrate community. However, large resuspension of river bed sediment results in a reduced abundance of macroinvertebrates. By controlling the transport processes of dissolved oxygen (DO), dissolved organic carbon (DOC), nutrients, temperature, and different patterns of hyporheic exchange strongly influence the structure of macroinvertebrate communities. Downwelling is more likely to produce rich invertebrate communities than upwelling. The magnitude for the hyporheic flux of 150-200 mm/d was optimal for the macroinvertebrate community in the Weihe River Basin. Above or below this rate results in a decline in community abundance and diversity. We suggest that research is conducted to better understand the effects of hyporheic exchange across bedforms on macroinvertebrate communities. The study supports any activities to preserve the ecological functions and health of rivers dominated by fine-grained sediments.
... The resulting similarity of identified macroinvertebrate community across different land uses is a general trend in urban streams due to higher rates of organic and inorganic solute contamination along altered riparian and stream reaches (Cuffney et al. 2010;Ricart et al. 2010). For instance, the presence of pollution-tolerant taxa (e.g. , Chironomidae, Oligochaeta) and absence of pollution-sensitive taxa (e.g., Perlidae, Psephenidae) may contribute to the similar aquatic invertebrate communities across different land uses, since the former can thrive in urban streams due to higher rates of water stress, while the latter requires pristine environmental conditions (de Paiva Silva et al. 2010;Chang et al. 2014;Mehring et al. 2017). ...
Urban development impacts stream ecosystems primarily via changes in hydrological regime, geomorphology, and in water quality. These changes in turn have biological effects. The University of the Philippines Diliman campus, located at the heart of the highly urbanized Quezon City, has gone through numerous developments in terms of landscape and infrastructure. Unlike the terrestrial environment, the extent to which these developments have impacted the campus waterways is unknown. Hence, our research aims to assess the overall condition of the waterways in the campus based on the benthic macroinvertebrate assemblages. A total of 19 stream reaches were sampled in November 2015 and 2016 in the following land use categories: academic/academic support units (six sites), campus core (eight sites), and parks and open spaces (five sites). One-way analysis of variance (ANOVA) detected significant spatial difference in several macroinvertebrate-based metrics, stream physicochemistry, and in-stream habitat condition elements. Our study reveals that all sampled stream reaches, regardless of their land use categories, are under poor to severe pollution conditions. All macroinvertebrate-based metrics and indices indicate degraded water quality and stream health. Our results are consistent with urban stream studies elsewhere, which suggest that land-based activities can be stressful for some aquatic organisms, and at times, result in reduced abundance and even reduction in species composition.
... Constructed wetlands confer hydrologic (e.g., peak flow reduction) as well as water quality benefits (e.g., removal of suspended solids, microbial pathogens, nutrients, and heavy metals) (Carleton et al., 2001;Karim et al., 2004;Vymazal, 2011). They also perform notable ancillary ecosystem services (e.g., related to aesthetics, recreation, habitat provisioning, biodiversity, and public health (Hsu et al., 2017)) as well as disservices (e.g., greenhouse gas emission, among others (Mehring et al., 2017)). ...
Constructed stormwater wetlands provide a host of ecosystem services, including potentially pathogen removal. We present results from a multi-wetland study that integrates across weather, chemical, microbiological and engineering design variables in order to identify patterns of microbial contaminant removal from inlet to outlet within wetlands and key drivers of those patterns. One or more microbial contaminants were detected at the inlet of each stormwater wetland (Escherichia coli and Enterococcus > Bacteroides HF183 > adenovirus). Bacteroides HF183 and adenovirus concentrations declined from inlet to outlet at all wetlands. However, co-removal of pathogens and fecal indicator bacteria only occurred at wetlands where microbial assemblages at the inlet (dominated by Proteobacteria and Bacteriodetes) were largely displaced by indigenous autotrophic microbial communities at the outlet (dominated by Cyanobacteria). Microbial community transitions (characterized using pyrosequencing) were well approximated by a combination of two rapid indicators: (1) fluorescent dissolved organic matter, and (2) chlorophyll a or phaeophytin a fluorescence. Within-wetland treatment of fecal markers and indicators was not strongly correlated with the catchment-to-wetland area ratio, but was diminished in older wetlands, which may point to a need for more frequent maintenance.
... Recent investigations suggest that chironomid larvae significantly stimulate the sedimentary release of N 2 O to the water column 22 , while N 2 O and CH 4 release does not significantly increase along with tubificid oligochaete abundance 23 . However, a recent study assessing urban wetlands showed that CH 4 and CO 2 fluxes correlated with tubificid abundance 24 . Experimental work with manipulated Baltic Sea sediment suggested that bivalves may induce a seven-to ten-fold increase in CH 4 efflux compared to sediment without macrofauna 16 , but no systematic studies have been conducted to investigate direct CH 4 production by benthic fauna and to quantify their impact on benthic GHG release. ...
Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change.
Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic
invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of
trace gas, isotope, and molecular analyses, we studied the direct and indirect contribution of two
macrofaunal groups, polychaetes and bivalves, to methane and nitrous oxide fuxes from coastal
sediments. Our results indicate that macrofauna increases benthic methane efux by a factor of up to
eight, potentially accounting for an estimated 9.5% of total emissions from the Baltic Sea. Polychaetes
indirectly enhance methane efux through bioturbation, while bivalves have a direct efect on methane
release. Bivalves host archaeal methanogenic symbionts carrying out preferentially hydrogenotrophic
methanogenesis, as suggested by analysis of methane isotopes. Low temperatures (8°C) also stimulate
production of nitrous oxide, which is consumed by benthic denitrifying bacteria before it reaches
the water column. We show that macrofauna contributes to GHG production and that the extent is
dependent on lineage. Thus, macrofauna may play an important, but overlooked role in regulating GHG
production and exchange in coastal sediment ecosystems.
