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1. A space‐for‐time framework for forecasting the effects of ocean stratification on zooplankton vertical habitat use and trait composition

   https://doi.org/10.1002/lno.12450  

   Matthews, Stephanie A. ; Ohman, Mark D. ( November 2023 , Limnology and Oceanography)

   The effects of environmental change on zooplankton communities, and more broadly, pelagic ecosystems are difficult to predict due to the high diversity of ecological strategies and complex interspecific interactions within the zooplankton. Trait‐based approaches can define zooplankton functional groups with distinct responses to environmental change. Analyses across multiple mesozooplankton groups can help identify key organizing traits. Here, we use the pronounced cross‐shore environmental gradient within the California Current Ecosystem in a space‐for‐time substitution to test potential effects of ocean warming and increased stratification on zooplankton communities. Along a horizontal gradient in sea‐surface temperature, water column stratification, and light attenuation, we test whether there are changes in zooplankton species composition, trait composition, and vertical habitat use. We employ DNA metabarcoding at two loci (18S‐V4 and COI) and digital ZooScan imaging of zooplankton sampled in a Lagrangian manner. We find that vertical distributions of many mesozooplankton taxa shift to deeper depths in the cross‐shore direction, and light attenuation is the strongest predictor of magnitude of change. Vertical habitat shifts vary among functional groups, with changes in vertical distribution most pronounced among carnivorous taxa. Herbivorous taxa remain associated with the chlorophyll maximum, especially in clear offshore waters. Our results suggest that increased stratification of this ocean region will lead to deeper depths occupied by some components of epipelagic mesozooplankton communities, and may result in zooplankton communities with more specialized feeding strategies, increased egg brooding, and more asexual reproduction.

    

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2. sFDvent: A global trait database for deep‐sea hydrothermal‐vent fauna

   https://doi.org/10.1111/geb.12975  

   Chapman, Abbie S. A. ; Beaulieu, Stace E. ; Colaço, Ana ; Gebruk, Andrey V. ; Hilario, Ana ; Kihara, Terue C. ; Ramirez‐Llodra, Eva ; Sarrazin, Jozée ; Tunnicliffe, Verena ; Amon, Diva J. ; et al ( July 2019 , Global Ecology and Biogeography)

   Traits are increasingly being used to quantify global biodiversity patterns, with trait databases growing in size and number, across diverse taxa. Despite growing interest in a trait‐based approach to the biodiversity of the deep sea, where the impacts of human activities (including seabed mining) accelerate, there is no single repository for species traits for deep‐sea chemosynthesis‐based ecosystems, including hydrothermal vents. Using an international, collaborative approach, we have compiled the first global‐scale trait database for deep‐sea hydrothermal‐vent fauna – sFDvent (sDiv‐funded trait database for theFunctionalDiversity ofvents). We formed a funded working group to select traits appropriate to: (a) capture the performance of vent species and their influence on ecosystem processes, and (b) compare trait‐based diversity in different ecosystems. Forty contributors, representing expertise across most known hydrothermal‐vent systems and taxa, scored species traits using online collaborative tools and shared workspaces. Here, we characterise the sFDvent database, describe our approach, and evaluate its scope. Finally, we compare the sFDvent database to similar databases from shallow‐marine and terrestrial ecosystems to highlight how the sFDvent database can inform cross‐ecosystem comparisons. We also make the sFDvent database publicly available online by assigning a persistent, unique DOI.

   Six hundred and forty‐six vent species names, associated location information (33 regions), and scores for 13 traits (in categories: community structure, generalist/specialist, geographic distribution, habitat use, life history, mobility, species associations, symbiont, and trophic structure). Contributor IDs, certainty scores, and references are also provided.

   Global coverage (grain size: ocean basin), spanning eight ocean basins, including vents on 12 mid‐ocean ridges and 6 back‐arc spreading centres.

   sFDvent includes information on deep‐sea vent species, and associated taxonomic updates, since they were first discovered in 1977. Time is not recorded. The database will be updated every 5 years.

   Deep‐sea hydrothermal‐vent fauna with species‐level identification present or in progress.

   .csv and MS Excel (.xlsx).

    

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3. Shifts in bacterial traits under chronic nitrogen deposition align with soil processes in arbuscular, but not ectomycorrhizal‐associated trees

   https://doi.org/10.1111/gcb.17030  

   Piñeiro, Juan ; Dang, Chansotheary ; Walkup, Jeth G. V. ; Kuzniar, Teagan ; Winslett, Rachel ; Blazewicz, Steven J. ; Freedman, Zachary B. ; Brzostek, Edward ; Morrissey, Ember M. ( November 2023 , Global Change Biology)

   Nitrogen (N) deposition increases soil carbon (C) storage by reducing microbial activity. These effects vary in soil beneath trees that associate with arbuscular (AM) and ectomycorrhizal (ECM) fungi. Variation in carbon C and N uptake traits among microbes may explain differences in soil nutrient cycling between mycorrhizal associations in response to high N loads, a mechanism not previously examined due to methodological limitations. Here, we used quantitative Stable Isotope Probing (qSIP) to measure bacterial C and N assimilation rates from an added organic compound, which we conceptualize as functional traits. As such, we applied a trait‐based approach to explore whether variation in assimilation rates of bacterial taxa can inform shifts in soil function under chronic N deposition. We show taxon‐specific and community‐wide declines of bacterial C and N uptake under chronic N deposition in both AM and ECM soils. N deposition‐induced reductions in microbial activity were mirrored by declines in soil organic matter mineralization rates in AM but not ECM soils. Our findings suggest C and N uptake traits of bacterial communities can predict C cycling feedbacks to N deposition in AM soils, but additional data, for instance on the traits of fungi, may be needed to connect microbial traits with soil C and N cycling in ECM systems. Our study also highlights the potential of employing qSIP in conjunction with trait‐based analytical approaches to inform how ecological processes of microbial communities influence soil functioning.

    

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4. Estimating the effects of non‐native species on nutrient recycling using species‐specific and general allometric models

   https://doi.org/10.1111/fwb.13092  

   Fritschie, Keith J. ; Olden, Julian D. ( February 2018 , Freshwater Biology)

   Non‐native species are now common in community assemblages, but the influence of multiple introductions on ecosystem functioning remains poorly understood. In highly invaded systems, one promising approach is to use functional traits to scale measured individuals’ effects on ecosystem function up to the community level. This approach assumes that functional traits provide a common currency among species to relate individuals to ecosystem functioning.

   The goals of this study were to (i) test whether the relationship between body size and ecosystem functioning (per capita nutrient recycling) was best described by general or species‐specific scaling models; (ii) relate community structure (total biomass, average body size, non‐native dominance) to aggregated, community‐level nutrient recycling rates and ratios; and (iii) determine whether conclusions regarding the relationships between community structure and aggregate ecosystem functioning differed between species‐specific and general scaling approaches.

   By combining experimental incubations and field surveys, we compare consumer‐mediated nutrient recycling of fish communities along a non‐native dominance gradient in the Verde River watershed of central Arizona,USA. Data from ˜340 field‐sampled freshwater fish demonstrated support for general allometric relationships predicted by the metabolic theory of ecology (NH₄‐N scaling coefficient = 0.72 [0.64–0.80];PO₄‐P = 0.67 [0.47–0.86]). However, the best‐fit models for N and P included species‐specific random effects for both allometric slopes and intercepts.

   According to species‐specific models, stream fish communities recycled 1–12 mmolNH₄‐N/hr (median = 2.8 mmol/hr) and 0.02–0.74 mmolPO₄‐P/hr (median = 0.07 mmol/hr) at N:P ratios between 13.3 and 83.5 (median = 28.8). General models generated similar estimates forNH₄‐N recycling but less accurate estimates forPO₄‐P. Stochastic simulations that incorporated error around allometric parameter estimates led to qualitatively similar but larger differences between general and species‐specific results.

   Community structure influenced aggregate nutrient recycling, but specific conclusions depended on the scaling approach. Total biomass explained much of the among‐community variation in aggregateNH₄‐N andPO₄‐P for both model types, whereas non‐native dominance alone best predicted variation in aggregate N:P. Surprisingly, species‐specific and general models both reached significant yet quantitatively opposing conclusions regarding the relationship between N:P supply and non‐native dominance.

   Study results indicate that shifting fish community structure can substantially alter ecosystem functioning in this river system. However, some inferred relationships between community structure and aggregate nutrient recycling varied depending on whether general or species‐specific scaling approaches were taken. Although trait‐based approaches to link environmental change, community structure and ecosystem function hold much promise, it will be important to consider when species‐specific versus general models are necessary to scale from individuals to ecosystems.

    

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5. Liana optical traits increase tropical forest albedo and reduce ecosystem productivity

   https://doi.org/10.1111/gcb.15928  

   Meunier, Félicien ; Visser, Marco D. ; Shiklomanov, Alexey ; Dietze, Michael C. ; Guzmán Q., J. Antonio ; Sanchez‐Azofeifa, G. Arturo ; De Deurwaerder, Hannes P. T. ; Krishna Moorthy, Sruthi M. ; Schnitzer, Stefan A. ; Marvin, David C. ; et al ( October 2021 , Global Change Biology)

   Lianas are a key growth form in tropical forests. Their lack of self‐supporting tissues and their vertical position on top of the canopy make them strong competitors of resources. A few pioneer studies have shown that liana optical traits differ on average from those of colocated trees. Those trait discrepancies were hypothesized to be responsible for the competitive advantage of lianas over trees. Yet, in the absence of reliable modelling tools, it is impossible to unravel their impact on the forest energy balance, light competition, and on the liana success in Neotropical forests. To bridge this gap, we performed a meta‐analysis of the literature to gather all published liana leaf optical spectra, as well as all canopy spectra measured over different levels of liana infestation. We then used a Bayesian data assimilation framework applied to two radiative transfer models (RTMs) covering the leaf and canopy scales to derive tropical tree and liana trait distributions, which finally informed a full dynamic vegetation model. According to the RTMs inversion, lianas grew thinner, more horizontal leaves with lower pigment concentrations. Those traits made the lianas very efficient at light interception and significantly modified the forest energy balance and its carbon cycle. While forest albedo increased by 14% in the shortwave, light availability was reduced in the understorey (−30% of the PAR radiation) and soil temperature decreased by 0.5°C. Those liana‐specific traits were also responsible for a significant reduction of tree (−19%) and ecosystem (−7%) gross primary productivity (GPP) while lianas benefited from them (their GPP increased by +27%). This study provides a novel mechanistic explanation to the increase in liana abundance, new evidence of the impact of lianas on forest functioning, and paves the way for the evaluation of the large‐scale impacts of lianas on forest biogeochemical cycles.

    

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