Response Of Benthic Communities Research Articles

Rapid, detrimental response of estuarine benthic macrofauna communities to pollution by littered cigarette filters and e-liquid

Cigarette butts are amongst the most littered single-use plastics on coasts, yet their impacts on marine ecosystems, especially on a community level, are not well understood. Recently, e-cigarettes have become popular and are a novel litter item in marine habitats. Preliminary research indicates that e-liquid can harm individual organisms, but few studies have been done and none on a community level. In a mesocosm experiment, we tested the impacts of cigarette butts (0.25, 1 butt L−1) or e-liquid (1 mL L−1) on infaunal invertebrate communities using intact sediment cores. After two weeks, the abundance of polychaetes, bivalves, and gastropods was significantly reduced in mesocosms with 1 cigarette butt L−1 compared with controls. Exposure to e-liquid resulted in severe oxygen depletion (<1 mg L−1) and almost complete mortality of sediment infauna after just four days. As litter, cigarette butts and disposable e-cigarettes both pose a threat to estuarine biodiversity.

Benthic diatom community response to the sudden rewetting of a coastal peatland

The coastline of the shallow southern Baltic Sea is a highly dynamic system of spits, lagoonal systems and subtidal flats. On the land side, coastal peatlands are common. Intact peatlands provide important ecosystem services, however, many peatlands have been severely degraded due to human activities. Many coastal peatlands are also separated from the Baltic Sea by artificial dunes or dykes in order to facilitate drainage and coastal protection measures. Due to their potential to act as carbon sinks, as well as buffer zones against sea level rise and flooding events, there is an increasing interest in the restoration and rewetting of coastal peatlands. Microphytobenthic communities are important primary producers in coastal systems and peatlands and diatoms are often the dominant microphytobenthic group in temperate regions. In November 2019, the removal of the dyke that separated the Polder Drammendorf (a drained, oligohaline peatland), from the adjacent Baltic Sea lagoon Kubitzer Bodden represented a unique chance to study the sudden rewetting of a degraded coastal peatland with brackish water and its effect on the microphytobenthos. The aims of this study were to investigate the poorly known diatom community composition of coastal peatlands, to determine the effects of flooding events on diatom composition and biomass in coastal peatlands as well as the effects of nutrient and substance release from the peatlands on the diatom communities of adjacent coastal waters. We investigated and documented the impact of this sudden rewetting on the benthic diatom communities of the peatland and the adjacent lagoon over the course of one year, applying the latest taxonomy and measuring key environmental factors. The results deepen the understanding of diatom community composition, taxonomy and ecology and explore the influence of land-sea exchange processes on the benthic diatoms of the Baltic Sea coast.

Differential spatio-temporal responses of Red Sea coral reef benthic communities to a mass bleaching event

Understanding how coral reefs respond to disturbances is fundamental to assessing their resistance and resilience, particularly in the context of climate change. Due to the escalating frequency and intensity of coral bleaching events, it is essential to evaluate spatio-temporal responses of coral reef communities to disentangle the mechanisms underlying ecological changes. Here, we used benthic data collected from 59 reefs in the Red Sea over five years (2014–2019), a period that encompasses the 2015/2016 mass bleaching event. Reefs were located within three different geographic regions with different environmental settings: north (Duba; Al Wajh), central (Jeddah; Thuwal), and south (Al Lith; Farasan Banks; Farasan Islands). Coral community responses were region-specific, with communities in the south being more promptly affected than those in the northern and central regions, with hard and soft coral cover dropping drastically in several reefs from around > 40% to < 5% two years after bleaching. Coral bleaching effects were particularly evident in the decrease of cover in branching corals. Overall, we documented a shift towards a dominance of macroalgae, turf algae, and crustose coralline algae (CCA). Using remote sensing data, we analyzed sea surface temperature (SST) regimes at the study sites to infer potential drivers of changes in benthic composition. Both SST and Degree Heating Weeks (DHW) only partially aligned with the responses of benthic communities, highlighting the need for more accurate predictors of coral bleaching in the Red Sea. In times of intense coastal development along Saudi Arabia’s Red Sea coast, our study provides crucial baseline information on developments in coral reef community composition, as well as to guide decision-making, namely restoration efforts.

Benthic taxonomic and functional diversity change across a depth gradient in the Southern Benguela Shelf ecoregion

Functional trait-based approaches improve biodiversity assessment and have consequently been gaining traction in ecology, including marine benthic studies. However, taxonomic diversity is still the default biodiversity metric applied to monitor benthic community responses to environmental variation despite not always representing functional diversity change. Therefore, we used Biological Traits Analysis (BTA) to quantify functional diversity for infauna and epifauna communities collected from the same locations across a depth gradient in the Southern Benguela Shelf ecoregion. Infauna experienced an increase in functional uniqueness with depth, whereas epifauna experienced an increase in functional redundancy with depth. As a result, the epifauna species assemblage predicted 43 % of the epifauna trait assemblage, whereas the infauna species assemblage predicted only 8 % of the infauna trait assemblage. These findings suggest that taxonomic diversity and functional diversity changes are not congruent within and between marine benthic faunal groups. We emphasize the need to utilise both biodiversity metrics when quantifying marine biodiversity for conservation and management objectives.

Disentangling the effect of space, time, and environmental and anthropogenic drivers on coastal macrobenthic β diversity in contrasting habitats over 15 years

Coastal zones are biodiversity hotspots and deliver essential ecosystem functions and services, yet they are exposed to multiple and interacting anthropogenic and environmental constraints. The individual and cumulative effects of these constraints on benthic communities, a key component of coastal ecosystems, and their variability across space and time, remains to be thoroughly quantified to guide conservation actions. Here, we explored how the presence of biogenic habitats influences the response of benthic communities to natural and anthropogenic constraints. We investigated this effect in both intertidal and subtidal habitats exposed to different pressures. We used data collected in the North-East Atlantic over 15 years (2005–2019) as part of the REBENT monitoring program, covering 38 sites of bare sediments, intertidal seagrass beds and maerl beds. We collected a range of environmental variables and proxies of anthropogenic pressures and used variation and hierarchical partitioning with redundancy analyses to estimate their relative effect on macrobenthic communities. We used descriptors modeling spatial and temporal structures (dbMEMs) to explore the scale of their effects and potential missing predictors. The selected variables explained between 53 % and 64 % of macrobenthic β diversity depending on habitat and depth. Fishing pressures, sedimentary and hydrodynamics variables stood out as the most important predictors across all habitats while proxies of anthropogenic pressures were overall more important in intertidal habitats. In the intertidal, presence of biogenic habitat strongly modulated the amount of explained variance and the identity of the selected variable. Across both tidal levels, analysis of models' residuals further indicated that biogenic habitats might mitigate the effect of extreme environmental events. Our study provides a hierarchy of the most important drivers of benthic communities across different habitats and tidal levels, emphasizing the prominence of anthropogenic pressures on intertidal communities and the role of biogenic habitats in mitigating environmental changes.

Response of inner shelf benthic foraminiferal community to different concentrations of dissolved oxygen under laboratory culture experiment

Dissolved oxygen, a vital parameter for a majority of marine organisms, may decline in the near future due to anthropogenic eutrophication in coastal waters. The effect of depleting dissolved oxygen on the marine benthic community is difficult to assess from field studies, as dissolved oxygen often co-varies with several other parameters, especially organic matter. The controlled laboratory culture experiments can help to assess the effect of a specific parameter on marine organisms. Foraminifera constitute a substantial fraction of the marine benthic organisms, and a few species are vulnerable to depleted oxygen. A majority of the previous culture experiments have used isolated specimens of individual benthic foraminiferal species. Although such studies helped to understand the response of individual species to a particular parameter, they have to be scaled up to understand the community-level response of benthic foraminifera. Here, we assess the community-level response of the shallow subtidal benthic foraminiferal community to five different oxygen concentrations (1.67 mL/L to 5.01 mL/L) in a laboratory culture experiment. The living benthic foraminiferal abundance was considerably high at the intermediate oxygen concentration, whereas it decreased at both the lower and higher concentrations. The decreasing dissolved oxygen caused poor preservation of dead benthic foraminifera due to a drop in pH. The relative abundance trend of the species belonging to the same genus was different, suggesting a species-specific response to the dissolved oxygen. The maximum abundance at 2.91 mL/L and the varying response of individual species clearly suggest a non-linear response of the benthic foraminiferal community to the dissolved oxygen.

Response of Microbial Communities to Naturally Occurring Radioactive Material-Contaminated Sediments: A Microcosm-Based Study.

There is a growing need to understand the potential ecological impacts of contaminants in offshore oil and gas infrastructure, especially if that infrastructure is to be left in situ as a decommissioning option. Naturally occurring radioactive material (NORM) is one type of contaminant found in solid deposits on internal surfaces of infrastructure that poses potential ecological harm if released into the marine environment. Microbes are important components of marine sediment ecosystems because they provide ecosystem services, yet the impacts of NORM contamination to these communities are not well understood. The present study aimed to investigate the response of benthic microbial communities to NORM-contaminated scale, collected from an offshore oil and gas system, via controlled laboratory microcosm studies. Changes to microbial communities in natural sediment and sediments spiked with NORM at radium-226 activity concentrations ranging from 9.5 to 59.8 Bq/kg (in partial equilibria with progeny) over 7 and 28 days were investigated using high-throughput sequencing of environmental DNA extracted from experimental sediments. There were no significant differences in microbial community composition between control and scale-spiked sediments over 7 and 28 days. However, we observed a greater presence of Firmicutes in the scale-mixed treatment and Chloroflexi in the scale-surface treatments after 28 days. This could suggest selection for species with contaminant tolerance or potential resilience to radiation and metal toxicity. Further research is needed to explore microbial tolerance mechanisms and their potential as indicators of effects of radionuclide-contaminated sediments. The present study demonstrated that microcosm studies can provide valuable insights about the potential impacts of contamination from oil and gas infrastructure to sediment microbial communities. Environ Toxicol Chem 2024;43:1648-1661. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Long‐term environmental flows restore benthic invertebrate communities in a highly regulated river

The construction of dams and other in‐stream structures for human use has altered river ecosystems worldwide. Dams degrade rivers, and environmental flow releases aim to mitigate flow alterations and restore rivers downstream of dams by returning elements of the pre‐regulation flow regime, resulting in an ecosystem that resembles a more natural state. We examined the responses of benthic invertebrate communities in riffles and pool‐edge habitats to an environmental flow regime (EFR) in the highly regulated Snowy River over 17 years (2000–2016). Benthic invertebrate communities significantly changed in response to prolonged increases in the magnitude of all components of the flow regime. The composition of the benthos in the regulated river became more dissimilar to pre‐EFR communities and more closely resembled those of nearby unregulated rivers. These changes were apparent in both riffle and pool‐edge habitats and were most pronounced when flow magnitudes were highest. Scrapers increased as flows increased, and in contrast, the relative abundances of gatherers declined with prolonged high flows and could be attributed to increased daily flows and high flow events mobilizing fine sediment and scouring benthic substrates. These results indicated that the EFR altered abiotic conditions or resources that previously limited invertebrate abundances, facilitating changes to the benthic community. Community changes we observed were in response to a flow regime that remained drastically lower than natural, demonstrating that restoration targets can be achieved with small flow increases that mimic natural flow patterns.

Impact of artificial barriers on benthic macroinvertebrate functional diversity in estuarine ecosystems

AbstractFunctional diversity research enhances our understanding of ecosystems and both their functioning and their responses to environmental variations. This study investigated the biological trait responses of benthic invertebrate communities to various environmental conditions in estuarine habitats. We analyzed benthic macroinvertebrate communities in freshwater and estuarine environments to compare their characteristics between estuary sites with and without artificial barriers. Moreover, we combined taxonomic analyses (species richness, abundance, and four community indices) with functional diversity indices and biological trait analyses. The major results are as follows: (i) the most important environmental factors shaping species distribution in estuarine habitats were salinity and electrical conductivity; (ii) comparing functional diversity indices, tidal estuaries revealed that seawater intrusion induced changes in species distribution and the dispersion of benthic macroinvertebrates; (iii) the presence or absence of artificial barriers in estuaries affected biological traits owing to the influence of specific functional strategies of certain species. Consequently, the presence or absence of artificial barriers in estuaries can lead to significant changes in habitat connectivity and functional diversity related to ecosystem functions. These findings indicate that the presence of artificial barriers can significantly influence the ecological dynamics of estuarine ecosystems, thereby affecting species distribution, functional diversity and habitat connectivity. Understanding these effects contributes to a more comprehensive understanding of ecosystem functionings, as it complements existing taxonomic findings and integrates information about the functional aspects of diverse ecosystems.

Baltic Sea coastal sediment-bound eukaryotes have increased year-round activities under predicted climate change related warming.

Climate change related warming is a serious environmental problem attributed to anthropogenic activities, causing ocean water temperatures to rise in the coastal marine ecosystem since the last century. This particularly affects benthic microbial communities, which are crucial for biogeochemical cycles. While bacterial communities have received considerable scientific attention, the benthic eukaryotic community response to climate change remains relatively overlooked. In this study, sediments were sampled from a heated (average 5°C increase over the whole year for over 50 years) and a control (contemporary conditions) Baltic Sea bay during four different seasons across a year. RNA transcript counts were then used to investigate eukaryotic community changes under long-term warming. The composition of active species in the heated and control bay sediment eukaryotic communities differed, which was mainly attributed to salinity and temperature. The family level RNA transcript alpha diversity in the heated bay was higher during May but lower in November, compared with the control bay, suggesting altered seasonal activity patterns and dynamics. In addition, structures of the active eukaryotic communities varied between the two bays during the same season. Hence, this study revealed that long-term warming can change seasonality in eukaryotic diversity patterns. Relative abundances and transcript expression comparisons between bays suggested that some taxa that now have lower mRNA transcripts numbers could be favored by future warming. Furthermore, long-term warming can lead to a more active metabolism in these communities throughout the year, such as higher transcript numbers associated with diatom energy production and protein synthesis in the heated bay during winter. In all, these data can help predict how future global warming will affect the ecology and metabolism of eukaryotic community in coastal sediments.

Depth variation in benthic community response to repeated marine heatwaves on remote Central Indian Ocean reefs.

Coral reefs are increasingly impacted by climate-induced warming events. However, there is limited empirical evidence on the variation in the response of shallow coral reef communities to thermal stress across depths. Here, we assess depth-dependent changes in coral reef benthic communities following successive marine heatwaves from 2015 to 2017 across a 5-25 m depth gradient in the remote Chagos Archipelago, Central Indian Ocean. Our analyses show an overall decline in hard and soft coral cover and an increase in crustose coralline algae, sponge and reef pavement following successive marine heatwaves on the remote reef system. Our findings indicate that the changes in benthic communities in response to elevated seawater temperatures varied across depths. We found greater changes in benthic group cover at shallow depths (5-15 m) compared with deeper zones (15-25 m). The loss of hard coral cover was better predicted by initial thermal stress, while the loss of soft coral was associated with repeated thermal stress following successive warming events. Our study shows that benthic communities extending to 25 m depth were impacted by successive marine heatwaves, supporting concerns about the resilience of shallow coral reef communities to increasingly severe climate-driven warming events.

Responses of multi-faceted benthic macroinvertebrates alpha and beta diversity to flooding in a highland floodplain

Flooding is an important process in natural fluvial floodplains. How the flood shapes aquatic community diversity in highland floodplains is still poorly understood. The aim of this study was to unravel the multi-faceted responses of benthic macroinvertebrate diversity to flooding and habitat environments in the Baihe River Basin from a taxonomic, phylogenetic, and functional perspective. We examined the alpha and beta diversity patterns of benthic macroinvertebrate communities in the mainstream, tributaries, and oxbow lakes during the normal water and flood periods. The results showed that the traditional alpha taxonomic diversity (TD) varied across habitats, despite minor changes after flood pulse. Alpha phylogenetic diversity (PD) decreased and alpha functional diversity (FD) markedly increased after flooding, with functional traits transiting toward risk avoidance. While all the three facets of beta diversity significantly responded to habitat differences, beta TD and PD shifted in response to flooding. Species turnover prominently increased in beta TD and PD after flood pulse, which contrasted with a weaker response of this process in FD. The explanatory power of significant environmental factors on both alpha and beta diversity was reduced by flooding. Compared with traditional TD, cooperating multi-faceted diversity could better depict the responses of benthic macroinvertebrate communities to flooding. The assessment and conservation of aquatic biodiversity in highland floodplains should take into account the three facets of alpha and beta diversity.

Benthic fauna along sandy beaches enriched by metals after mining disaster

In 2015, 60 million tons of ore tailings from the Fundão dam failure entered the Doce River basin, Brazil, and reached surrounding sandy beaches. This study evaluated the influence of sedimentology and morphology of beaches that received mining tailings on chemical element concentrations and consequent benthic community responses. We collected sediments for physical (granulometry, heavy mineral, and calcium carbonate content) and geochemical (chemical elements) analyses and biological diversity parameters (benthic macro- and meiofauna density, richness, and composition) on 8 beaches with different morphodynamic types. Beaches with more dissipative characteristics retained the highest contents of mud, As, Fe, Mn, V, and heavy minerals, present in the tailings. We also recorded the lowest density and richness of macrofauna on these beaches, compared to more reflective beaches. These results contradict the global trend, suggesting that anthropic disturbances outweigh the effects of morphodynamics in structuring the benthic fauna community, mainly in dissipative sandy beaches.

Responses by benthic invertebrate community composition to dissolved organic matter in lakes decline substantially above a threshold concentration

Abstract Dissolved organic matter (DOM), often measured as dissolved organic carbon (DOC), plays a fundamental role in influencing the structure and function of lake ecosystems. Due to the myriad ecosystem effects of DOM, widespread observations of long‐term increasing DOM concentrations have received much attention from ecologists. DOM positively influences primary production and consumer production at low concentrations due to the fertilising influence of bound nutrients. However, beyond a unimodal peak in production, a reduced light environment may result in a negative effect on production. This unimodal model has been largely developed and tested in lakes with low to moderate DOM concentrations (i.e., typically ≤10 mg/L DOC). To understand ecological responses in lakes across a larger range in DOM concentrations, we examined the response of benthic invertebrate communities in 148 Swedish lakes with DOM concentrations ranging between 0.67 and 32.77 mg/L DOC. We found that increasing DOM concentrations had a strong effect on invertebrate community composition below c. 10 mg/L. Across this range, abundances of individual taxa both increased and decreased, probably in response to environmental change induced by DOM. However, in lakes above this concentration, increasing DOM had minimal influence on community composition. As DOM concentrations continue to increase, faunal communities in lakes below this 10 mg/L DOC threshold are likely to undergo substantial change whereas those above this threshold are likely to be minimally impacted.

Submarine outfall and new sewage treatment plant modulate the response of intertidal benthic communities in a SW Atlantic area

Spatio-temporal responses of the intertidal macrobenthic community to the effects of a submarine outfall (SO) and a new sewage treatment plant (EDAR) were evaluated, analyzing changes in macrofaunal assemblages and community structure. Study was conducted in a SW Atlantic coastal area in 4 stages: BSO (Before the SO), Du (During the construction of the SO), ASO (After the SO start-up) and AEDAR (After the treatment plant start-up). Boccardia proboscidea and Brachidontes rodriguezii contributed most to the differences between all stages at the site nearest to the discharge point. Number of individuals was highest at BSO and Du. Richness and diversity were lowest at the BSO and highest at the Du. Furthermore, the richness decreased slightly, and the diversity increased at AEDAR. Evenness was highest at the BSO and AEDAR. The nestedness was the dominant process driving the differences between the BSO stage community and the rest of the stages. SO affects the composition and structure of the intertidal macrobenthic community near the outfall area, as organic matter discharge further offshore favour the development of a more diverse intertidal community, including species sensitive to organic enrichment.

Seasonal dynamics response mechanism of benthic microbial community to artificial reef habitats

Artificial reefs (ARs) have been globally deployed to enhance and restore coastal resource and ecosystems. Microorganisms play an essential role in marine ecosystems, while the knowledge regarding the impact of ARs on microecology is still limited, particularly data concerning the response of benthic microbial community to AR habitats. In this study, the seasonal dynamics of benthic microbial community in AR and adjacent non-artificial reef (NAR) areas surrounding Xiaoshi Island were investigated with high-throughput sequencing technology. The results revealed that the diversity and structure of microbial community between AR and NAR both displayed pronounced seasonal dynamics. There was a greater influence of season factors on microbial communities than that of habitat type. The microbial communities in AR and NAR habitats were characterized by a limited number of abundant taxa (ranging from 5 to 12 ASVs) with high relative abundance (8.35–25.53%) and numerous rare taxa (from 5994 to 12412 ASVs) with low relative abundance (11.91%–24.91%). Proteobacteria, Bacteroidota and Desulfobacterota were the common predominant phyla, with the relative abundances ranging from 50.94% to 76.76%. A total of 52 biomarkers were discovered, with 15, 4, 6, and 27 biomarkers identified in spring, summer, autumn and winter, respectively. Co-occurrence network analysis indicated that AR displayed a more complex interaction pattern and higher susceptibility to external disturbances. Furthermore, the neutral model and βNTI analyses revealed that the assembly of microbial communities in both AR and NAR is significantly influenced by stochastic processes. This study could provide valuable insights into the impact of ARs construction on the benthic ecosystems and would greatly facilitate the development and implementation of the future AR projects.

Diversity, distribution patterns and indicatory potential of echinoderm communities of the tropical East Atlantic (Gulf of Guinea): Influence of multiple natural and anthropogenic factors along a 25–1000 m depth gradient

All earlier studies of the West African echinoderm fauna have focused on taxonomy, and general knowledge about benthic community responses to various human related threats are poorly diagnosed and not monitored along the whole African coast. Our analysis of diversity and distribution patterns of Ghanaian echinoderms yielded 36 species. Material was collected at nine transects distributed along the coast of Ghana (25–1000 m depth range, total of over 270 samples). Gradual decreases in species richness, diversity, evenness and abundance were observed along the depth gradient, with the most diverse fauna being recorded on the shelf (25–50 m). The most abundant species were Ophiactis luetkeni and Ophiothrix congensis, although both had very patchy distributions. Cluster analysis separated shelf communities (25–100 m) from slope communities (500–1000 m), although on a low level of similarity. Our analysis allowed to select most vulnerable benthic habitats that should be amongst priorities of the future monitoring. Local influence of arsenic was observed at some shelf sites, while slope fauna was affected by elevated levels of hydrocarbons and barium. Changes in salinity and fluorescence also influenced echinoderm assemblages. The most general trend showed patchily distributed, diverse shallow water fauna being influenced by increased microhabitat diversity and food availability, while depauperate slope fauna was affected by local disturbances associated with oil extraction. Tropical echinoderm communities have a great potential as indicators of even minor and local pollution, although high patchiness and low abundance creates difficulties in the multivariate analysis. High sampling effort and high number of replicates allowed to minimise those problems and demonstrated small scale microhabitat diversity.

Macroinvertebrates reveal environmental gradients: methods and method development in the Ob River basin

AbstractThe Ob is the seventh longest river in the world and its length (including the largest tributary Irtysh) is 5410 km. The huge size of the Ob River catchment and diverse natural resources of the region give rise to numerous anthropogenic factors affecting aquatic ecosystems. The patterns of longitudinal changes in the composition aquatic communities are still uncertain, especially for large rivers. To assess the role of environmental factors in the structure of communities, we analyzed longitudinal changes in the species richness, abundance, and biomass of macroinvertebrate communities along a 3363-km section of the Ob River. The trends of longitudinal changes in macroinvertebrate communities differed significantly on sandy, silty, and rocky substrates. For sandy substrates, an important factor in the separation of communities was the Novosibirsk Reservoir, for rocky substrates—the influence of the Altai Mountains, and for silty substrates—the location of large cities. The results emphasize the importance of taking into account the differences in bottom sediments and the patterns of longitudinal changes in bottom communities for bio-assessment of the ecological status of large rivers. Overall, we propose macroinvertebrates for bioindication along the Ob River, with regard to type, anthropogenic impact, stress factors, and response of benthic communities.

How Benthic Sediment Microbial Communities Respond to Glyphosate and Its Metabolite: a Microcosm Experiment.

Glyphosate is the most commonly used agricultural herbicide in the world. In aquatic ecosystems, glyphosate often adsorbs to benthic substrates or is metabolized and degraded by microorganisms. The effects of glyphosate on microbial communities vary widely as microorganisms respond differently to exposure. To help understand the impacts of glyphosate on the sediment microbiome, we conducted a microcosm experiment examining the responses of benthic sediment microbial communities to herbicide treatments. Sediments from a prairie pothole wetland were collected, and 16S rRNA gene sequencing was used to analyze community composition 2-h and 14-days after a single treatment of low (0.07 ppm), medium (0.7 ppm), or high (7 ppm) glyphosate, aminomethylphosphonic acid (glyphosate metabolite), or a glyphosate-based commercial formula. We found no significant differences in microbial community composition across treatments, concentration levels, or day of sampling. These findings suggest that microbial species in the Prairie Pothole Region of North America may be tolerant to glyphosate exposure.

A first look at megabenthic community responses to seasonal change using the new Holyrood Subsea Observatory in Conception Bay, NL

Sub-Arctic seafloor communities rely on seasonal phytoplankton blooms for food, revealing a tight benthic-pelagic coupling. To maximize resource availability for offspring, organisms such as snow crabs, sea stars, and sea cucumbers synchronize their reproductive and feeding behaviours with spring blooms. Due to climate change, spring blooms are occurring earlier in sub-Arctic regions, leading to a possible mismatch between timing of resource availability and important life-history behaviours. Here, we utilize high-frequency time-series observations from the Holyrood Subsea Observatory, a new cabled seafloor observatory deployed in Conception Bay, Newfoundland. We use hourly data collected from environmental sensors (Conductivity-Temperature-Depth, Acoustic Doppler Current Profiler, fluorometer), a near-surface mooring (fluorometer), and a video camera to identify and quantify abundance and diversity of benthic megafauna, and to determine how community composition changed from pre-bloom to full bloom conditions. Data analysis revealed striking temporal changes in benthic activity, with the notable emergence of Psolus cf. phantapus sea cucumbers (up to 289.9 indiv./m2) coinciding with increased chlorophyll-a concentration and seawater temperature. At least three dense schools of forage fish, two Atlantic herring (79 and 144 indiv. frame−1) and one capelin (91 indiv. frame−1), were observed during the main bloom between May 5 and June 16. This study provides the first high-frequency in situ observations of benthic community response to seasonal food input in the region. The high temporal resolution made it possible to record the precise timing of the of Psolus cf. phantapus emergence in relation to the timing of food input to the seafloor, which will provide a baseline to monitor phenology as climate change progresses. Changes to the timing of spring blooms have implications for sub-Arctic fisheries productivity and ecosystem functioning, making continuous long-term monitoring of seafloor communities essential.