Submerged aquatic vegetation (SAV) provides essential ecosystem services, yet how plant presence and architecture facilitate habitat remains poorly understood in tidal freshwater systems. To address this, we evaluated how differing SAV habitats facilitate macroinvertebrate assemblages in the Pamunkey River, Virginia. We hypothesized that (1) SAV presence supports greater macroinvertebrate abundance and diversity than Bare substrate, and (2) structurally complex non-native SAV beds host more abundant and diverse communities than simply structured native beds. Multiple samplings in April and June 2026 across Bare sediment, native Zannichellia palustris beds, and Mixed non-native (Hydrilla-dominated) meadows yielded 3,948 invertebrates across 44 taxa. These abundant organisms bolster lower-trophic energy transfer, as the dominant taxa (Diaphanosoma sp. J24, Tanypodinae gen. sp. A1, and Gammarus sp. A7) serve as key prey for higher-trophic predators. Habitat type was a significant driver of invertebrate community structure (R2 = 0.327, p = 0.001). Vegetated habitats harbored consistently higher abundance and richness than Bare substrate, but faunal abundance peaked in epibenthic communities of Mixed meadows (20,754 org. m-2) significantly outperforming both native Zannichellia (3,183 org. m-2) and Bare substrate (2,037 org m-2; p < 0.001). However, when normalized by plant biomass, native Zannichellia supported a significantly greater invertebrate density (1,000 g-1) than Mixed meadows (45 g-1; p < 0.001) and uniquely hosted five indicator taxa (Ostracoda ord. fam. gen. sp. A32, Ceratopogonidae gen. sp. A11, Copepoda ord. fam. gen. spp. A30 & A31, and Ephemeridae gen. sp. A13). These findings demonstrate that while high non-native biomass expands gross habitat capacity for dominant prey species, native SAV provides distinct, high-efficiency microhabitats for sensitive taxa, making native plant preservation essential for maintaining estuarine food web integrity.

1. Community assembly in aquatic habitats is heavily influenced by hydrology, but understanding the influence of other habitat conditions is also critical. Most studies focus on comparisons of geographically close communities that exist under diverse hydrological regimes, but this framework limits our ability to understand how conditions other than hydrology shape ephemeral wetland communities. Here, we investigated how macroinvertebrate communities vary with local, landscape, and climate variables in ephemeral wetlands across a large geographic range with few geographic barriers. 2. We sampled ephemeral wetlands in North Dakota, New Mexico, and Texas (USA) in 2021 and in North Dakota and New Mexico in 2022. We used an array of hydrographic, climate, landscape, and spatial variables to relate taxonomic and functional macroinvertebrate community composition and diversity to habitat conditions. 3. Taxonomic composition was overwhelmingly different among states and between years: landscape-scale refuge availability explained variation in taxonomic composition, but local and climate-scale variables only explained variation within the context of other variables. Trait composition was similar between most sampling groups, but distinct trait assemblages occurred in the North Dakota 2021 communities. No predictor variable matrix explained trait composition alone, but local, climate, landscape, and spatial arrangement predicted composition when considering the overlapping influence of other variables. Taxa and trait diversity indices were associated with increased refuge habitat at landscape scale. 4. Our results show consistent trait structure across a large geographical scale in hydrologically similar wetlands, despite almost complete taxonomic turnover between regions. Patterns in taxonomic and functional composition imply that incorporating predictor variables at multiple scales is critical in understanding ephemeral wetland community composition. 5. Despite similar hydrological regimes and potential for connectivity via dispersal, taxa replacement is high in ephemeral wetlands across regions within a single grassland macrosystem. Taxonomic composition and overall diversity change with the context provided by a diverse suite of structuring variables. Further, we show that in most cases, ephemeral hydrology elicits a similar trait response across climate regions.

Biodiversity can confer temporal stability to ecosystem processes through asynchrony in species' abundances and may promote asynchrony and stability of commercial fishing harvests derived from exploited species. However, the linkages between asynchrony in the population dynamics of commercially harvested species and asynchrony of associated harvests have been difficult to resolve due to ecological, social, and economic dynamics that mediate resource extraction. Here, we explored coupled human-ecological relationships and emergent asynchrony using commercial fishing harvest data and fisheries-independent trawl surveys in two regions (Maryland and Virginia) of Chesapeake Bay, USA, from 2002 to 2018. For each region, we sought to identify how seasonal (within-year) asynchrony among harvested fish species contributed to (1) seasonal asynchrony in the harvests of these species and (2) within-year stability and economic value of harvests. We found that, in Maryland, seasonal closure of striped bass (Morone saxatilis) fishing resulted in asynchrony by forcing switching to alternative stocks. In Virginia, seasonal migration of harvested species to and from the Chesapeake Bay promoted harvest compensation and therefore harvest asynchrony. However, this effect was negated by the concurrent effects of an increase in the evenness of species dynamics on harvest compensation, reflecting changes in fishing patterns, primarily following declines in the biomass of Atlantic croaker (Micropogonias undulatus). Our findings show that both social (direct management actions and behavioral responses) and emergent properties of ecological systems can influence asynchrony in dynamics of exploited populations and commercial harvests, with implications for their continued management and sustainability.

Shifting precipitation patterns associated with global climate change are significantly impacting lotic ecosystems worldwide. To understand how these changes influence stream fish community assembly, we conducted a space-for-time study under a steep natural rainfall gradient in the coastal plain region of Texas (USA). Leveraging multi-year intra-annual fish surveys and environmental data from nine streams, we assessed the effects of precipitation regime on functional diversity and trait distributions, focusing on the relative importance of environmental filtering, interspecific interaction, and individual environmental drivers. Fish communities transitioned from functionally underdispersed to overdispersed with increasing precipitation rate, suggesting that filtering was a key assembly mechanism in more arid communities, while species interaction played a more important role under wetter climates. Deviations in functional dispersion across the rainfall gradient were best explained by changes in relative distributions of traits (functional evenness) as opposed to losses or additions of traits (functional richness) between sites, and the best predictors of these deviations were mean annual rainfall, low-flow frequency, and prevalence of hypoxic conditions. Proportional abundances of hypoxia-tolerant, herbivorous taxa within communities were associated mainly with the same predictors, illustrating the importance of these fishes’ increasing prevalence with increased aridity. Relationships between their abundances and benthic primary producer densities may also point to changes in grazing pressure, possibly stemming from top-down trophic processes. The shift from communities with low functional diversity dominated by hypoxia-tolerant, herbivorous taxa to more diverse assemblages as rainfall rates increased was non-linear, which may represent an important precipitation-driven threshold in community assembly. Our observations across this spatial rainfall gradient may translate to similar community-level changes in lotic ecosystems experiencing temporally shifting precipitation patterns, ultimately leading to increased understanding of relationships between functional trait distributions and climate, as well as providing valuable knowledge for predicting the impacts of changing precipitation regimes in freshwater ecosystems worldwide.

Multiple-use conflicts of the marine benthos (“bottom-use conflicts”) are increasing as humans expand use of the coastal zone. These conflicts necessitate balanced policies that consider the economic and ecological benefits of different bottom uses. In the Virginia coastal lagoons on the US east coast, there is a potential bottom-use conflict between hard clam (Mercenaria mercenaria) aquaculture and seagrass (Zostera marina) meadows. We leveraged two decades (2001–2021) of aerial imagery and environmental data to quantify historic trends in bottom use, assess the realized niche of seagrass and clam aquaculture across depth, sand fraction, root mean square (RMS) velocity, fetch, and sea surface temperature (SST) anomaly, and used random forest models to predict the potential extent of seagrass, clam aquaculture, and bottom-use conflict. We found growth in the coverage of both seagrass (+ 3373

Predation is a key process that influences the structure and functioning of ecosystems. Tethering experiments, which involve restraining prey or prey analogs in field settings, are used to evaluate predation with minimal manipulation of predators and the environment. However, tethering experiments alter the behavior of mobile prey, an issue that increases in severity with prey mobility and reliance on that mobility to evade predators, resulting in artifacts that complicate the interpretation of experimental findings. Given their widespread and rapidly evolving use, we review and reconsider the applications of tethering experiments in marine ecosystems, their utility in measuring predation, associated artifacts, theoretical, methodological, and statistical considerations and challenges, and how to overcome these. Breaking down the predation process into its successive stages (encounter, attack, capture, and consumption), we consider that tethering experiments effectively measure two major aspects of predation: (1) relative predation rates (requiring all four stages, and resulting in successful predation) and (2) predation risk (requiring only encounter and attack). We suggest that tethering experiments be designed to test hypotheses that target particular stages or all stages of the predation process and its drivers, through manipulating tethering experimental designs, conducting direct observations of tethering experiments, collecting additional community or environmental data, combining tethering with other experimental approaches, and through statistical analyses. This general approach facilitates both our understanding of the limitations and utility of tethering experiments to compare patterns and identify drivers of predation rates and risk in the field, topics of study that remain underrepresented in the literature.

Disturbances can produce a spectrum of short- and long-term ecological consequences that depend on complex interactions of the characteristics of the event, antecedent environmental conditions, and the intrinsic properties of resistance and resilience of the affected biological system. We used Hurricane Harvey's impact on coastal rivers of Texas to examine the roles of storm-related changes in hydrology and long-term precipitation regime on the response of stream invertebrate communities to hurricane disturbance. We detected declines in richness, diversity and total abundance following the storm, but responses were strongly tied to direct and indirect effects of long-term aridity and short-term changes in stream hydrology. The amount of rainfall a site received drove both flood duration and flood magnitude across sites, but lower annual rainfall amounts (i.e. aridity) increased flood magnitude and decreased flood duration. Across all sites, flood duration was positively related to the time it took for invertebrate communities to return to a long-term baseline and flood magnitude drove larger invertebrate community responses (i.e. changes in diversity and total abundance). However, invertebrate response per unit flood magnitude was lower in sub-humid sites, potentially because of differences in refuge availability or ecological-evolutionary interactions. Interestingly, sub-humid streams had temporary large peaks in invertebrate total abundance and diversity following recovery period that may be indicative of the larger organic matter pulses expected in these systems because of their comparatively well-developed riparian vegetation. Our findings show that hydrology and long-term precipitation regime predictably affected invertebrate community responses and, thus, our work underscores the important influence of local climate to ecosystem sensitivity to disturbances.

Coastal habitat-forming species provide protection and essential habitat for fisheries but their ability to maintain these services are under threat from novel stressors including rising temperatures. Coastal habitat restoration is a powerful tool to help mitigate the loss of habitat-forming species, however, many efforts focus on reintroducing a single, imperilled species instead of incorporating alternatives that are more conducive to current and future conditions. Seagrass restoration has seen mixed success in halting local meadow declines but could begin to specifically utilize generalist seagrasses with climate change-tolerant and opportunistic life history traits including high reproduction rates and rapid growth. Here, we built on decades of successful eelgrass (Zostera marina) restoration in the Chesapeake Bay by experimentally testing seed-based restoration potential of widgeongrass (Ruppia maritima)-a globally distributed seagrass that can withstand wide ranges of salinities and temperatures. Using field experiments, we evaluated which seeding methods yielded highest widgeongrass survival and growth, tested if seeding widgeongrass adjacent to eelgrass can increase restoration success, and quantified how either seagrass species changes restored bed structure, invertebrate communities, and nitrogen cycling. We found that widgeongrass can be restored via direct seeding in the fall, and that seeding both species maximized total viable restored area. Our pilot restoration area increased by 98% because we seeded widgeongrass in shallow, high temperature waters that are currently unsuitable for eelgrass survival and thus, would remain unseeded via only eelgrass restoration efforts. Restored widgeongrass had higher faunal diversity and double animal abundance per plant biomass than restored eelgrass, whereas restored eelgrass produced three times greater plant biomass per unit area and higher nitrogen recycling in the sediment. Synthesis and applications. Overall, we provide evidence that supplementing opportunistic, generalist species into habitat restoration is a proactive approach to combat climate change impacts. Specifically, these species can increase trait diversity which, for our study, increased total habitat area restored-a key factor to promote seagrass beds' facilitation cascades, stability, and grass persistence through changing environments. Now, we call for tests to determine if the benefits of restoration with generalist species alone or in conjunction with historically dominant taxa are broadly transferrable to restoration in other marine and terrestrial habitats. Overall, we provide evidence that supplementing opportunistic, generalist species into habitat restoration is a proactive approach to combat climate change impacts. Specifically, these species can increase trait diversity which, for our study, increased total habitat area restored-a key factor to promote seagrass beds' facilitation cascades, stability, and grass persistence through changing environments. Now, we call for tests to determine if the benefits of restoration with generalist species alone or in conjunction with historically dominant taxa are broadly transferrable to restoration in other marine and terrestrial habitats.image

As climate change continues to shift the distributions of species worldwide, understanding where, why, and how organisms move beyond their historical ranges is of critical importance. Here, we report on the expansion of pinfish Lagodon rhomboides poleward along the mid-western Atlantic in response to rising temperatures. Pinfish are a key interactor in nearshore subtidal habitats like seagrasses in the southwestern Atlantic and Gulf of Mexico, but they have been historically sparse north of the ecotone at Cape Hatteras, North Carolina, USA. Using multi-decadal trawl surveys, we show that while pinfish have been present both below (North Carolina) and above (Virginia and Maryland) this ecotone for many years, they have increasingly intruded into restored eelgrass (Zostera marina) meadows in the coastal bays of Virginia over the past decade. In 2022, for instance, pinfish abundances in Virginia equaled those observed historically in North Carolina. To understand the factors promoting these changes in abundance, we used a passive drifter model to show that these increases are not necessarily tied to changes in offshore currents. Instead, linear models revealed that the local abundance of pinfish in Virginia correlates most with inshore summertime water temperatures. Thus, favorable environmental conditions of the recipient bays appear to encourage greater recruitment and therefore greater abundance of pinfish. Given their outsized ecological role in subtropical ecosystems, and that the climate will continue to warm, our findings suggest that pinfish may soon come to dominate the structure and functioning of temperate seagrass meadows in Virginia and beyond.

Climate change is altering the functioning of foundational ecosystems. While the direct effects of warming are expected to influence individual species, the indirect effects of warming on species interactions remain poorly understood. In marine systems, as tropical herbivores undergo poleward range expansion, they may change food web structure and alter the functioning of key habitats. While this process ('tropicalization') has been documented within declining kelp forests, we have a limited understanding of how this process might unfold across other systems. Here we use a network of sites spanning 23° of latitude to explore the effects of increased herbivory (simulated via leaf clipping) on the structure of a foundational marine plant (turtlegrass). By working across its geographic range, we also show how gradients in light, temperature and nutrients modified plant responses. We found that turtlegrass near its northern boundary was increasingly affected (reduced productivity) by herbivory and that this response was driven by latitudinal gradients in light (low insolation at high latitudes). By contrast, low-latitude meadows tolerated herbivory due to high insolation which enhanced plant carbohydrates. We show that as herbivores undergo range expansion, turtlegrass meadows at their northern limit display reduced resilience and may be under threat of ecological collapse.

Climate change is expected to alter rainfall and temperature regimes across the world. The hydrology and riparian zone vegetation of lotic ecosystems are tightly linked to rainfall and a mechanistic understanding of the effects of rainfall on lotic ecosystems is needed to forecast the ecological impacts of climate change. However, it is difficult to isolate rainfall effects from other environmental variables that covary across climates. To address this, we leveraged a unique steep rainfall gradient with few covarying changes in elevation, temperature, and geology to evaluate the effects of rainfall on stream invertebrate communities. We surveyed nine streams in the Texas Gulf Coast Prairie distributed along a 550-1,350 mm/year rainfall gradient. Four sites were classified as drier semi-arid streams (<750 mm annual rainfall) and five sites were classified as wetter sub-humid streams (>750 mm annual rainfall). A suite of characteristics including benthic invertebrate community metrics, flow conditions, and water quality variables were assessed monthly for 14 months at each site to relate precipitation regime to stream structure and function. Precipitation regime was observed to be a master explanatory variable. As annual rainfall increased, the flow environment became more stable within seasons and predictable across seasons, influencing spatial structure and temporal variability of invertebrate community composition. Wetter streams were dominated by slower growing taxa without adaptions for desiccation resistance and strong dispersal. Wetter sites displayed seasonal variation in community composition and species richness, whereas temporal variation in communities in drier streams was controlled by stochastic variation in flow conditions. These observations show that differences in local annual rainfall correlated with major changes to community structure and functional composition. We hypothesise that this association is related to the connection of rainfall to hydrological stability, particularly the frequency of low flow disturbances, and the subsequent effects on riparian vegetation and temporally available niches to stream invertebrates. Our work adds to evidence that alterations in precipitation patterns associated with climate change have sweeping impacts on lotic fauna.

Biodiversity inventories and monitoring techniques for marine fishes often overlook small (<5 cm), bottom-associated ('cryptobenthic') fishes, and few standardized, comparative assessments of cryptobenthic fish communities exist. We sought to develop a standardized, quantitative survey method for cryptobenthic fishes that permits their sampling across a variety of habitats and conditions. Fish-specific autonomous reef monitoring structures (FARMS) are designed to sample cryptobenthic fishes using a suite of accessible and affordable materials. To generate a variety of microhabitats, FARMS consist of three layers of stacked PVC pipes in three different sizes, as well as a bottom and top level of loose PVC-pipe fragments in a mesh basket. We deployed FARMS across a variety of habitats, including coral reefs, seagrass beds, oyster reefs, mangroves, and soft-bottom habitats across six locations (Hawai'i, Texas, Panama, Saudi Arabia, Brazil, and Curacao). From shallow estuaries to coral reefs beyond 100 m depth, FARMS attracted distinct communities of native cryptobenthic fishes with strong site or habitat specificity. Comparing the FARMS to communities sampled with alternative methods (enclosed clove-oil stations on coral reefs in Panama and oyster sampling units on oyster reefs in Texas) suggests that FARMS yield a subset of cryptobenthic fish species that are representative of those present on local coral and oyster reefs. While FARMS yield fewer individuals per sample, they are efficient sampling devices relative to the sampled area. We demonstrate that FARMS represent a useful tool for standardized collections of cryptobenthic fishes. While natural substrata are bound to yield more mature communities with a larger number of individuals and wider range of specialist species, the potential to deploy and retrieve FARMS in turbid environments, beyond regular SCUBA depth, and where fish collections using anaesthetics or ichthyocides are forbidden suggests that they are a valuable complementary technique to survey fishes in aquatic ecosystems. Deploying FARMS in locations and habitats where cryptobenthic fish communities have not been studied in detail may yield many valuable specimens of unknown or poorly known species.

Global change has converted many structurally complex and ecologically and economically valuable coastlines to bare substrate. In the structural habitats that remain, climate-tolerant and opportunistic species are increasing in response to environmental extremes and variability. The shifting of dominant foundation species identity with climate change poses a unique conservation challenge because species vary in their responses to environmental stressors and to management. Here, we combine 35 y of watershed modeling and biogeochemical water quality data with species comprehensive aerial surveys to describe causes and consequences of turnover in seagrass foundation species across 26,000 ha of habitat in the Chesapeake Bay. Repeated marine heatwaves have caused 54% retraction of the formerly dominant eelgrass ( Zostera marina ) since 1991, allowing 171% expansion of the temperature-tolerant widgeongrass ( Ruppia maritima ) that has likewise benefited from large-scale nutrient reductions. However, this phase shift in dominant seagrass identity now presents two significant shifts for management: Widgeongrass meadows are not only responsible for rapid, extensive recoveries but also for the largest crashes over the last four decades; and, while adapted to high temperatures, are much more susceptible than eelgrass to nutrient pulses driven by springtime runoff. Thus, by selecting for rapid post-disturbance recolonization but low resistance to punctuated freshwater flow disturbance, climate change could threaten the Chesapeake Bay seagrass’ ability to provide consistent fishery habitat and sustain functioning over time. We demonstrate that understanding the dynamics of the next generation of foundation species is a critical management priority, because shifts from relatively stable habitat to high interannual variability can have far-reaching consequences across marine and terrestrial ecosystems.

A tenet of ecology is that temporal variability in ecological structure and processes tends to decrease with increasing spatial scales (from locales to regions) and levels of biological organization (from populations to communities). However, patterns in temporal variability across trophic levels and the mechanisms that produce them remain poorly understood. Here we analyzed the abundance time series of spatially structured communities (i.e., metacommunities) spanning basal resources to top predators from 355 freshwater sites across three continents. Specifically, we used a hierarchical partitioning method to disentangle the propagation of temporal variability in abundance across spatial scales and trophic levels. We then used structural equation modeling to determine if the strength and direction of relationships between temporal variability, synchrony, biodiversity, and environmental and spatial settings depended on trophic level and spatial scale. We found that temporal variability in abundance decreased from producers to tertiary consumers but did so mainly at the local scale. Species population synchrony within sites increased with trophic level, whereas synchrony among communities decreased. At the local scale, temporal variability in precipitation and species diversity were associated with population variability (linear partial coefficient, β = 0.23) and population synchrony (β = -0.39) similarly across trophic levels, respectively. At the regional scale, community synchrony was not related to climatic or spatial predictors, but the strength of relationships between metacommunity variability and community synchrony decreased systematically from top predators (β = 0.73) to secondary consumers (β = 0.54), to primary consumers (β = 0.30) to producers (β = 0). Our results suggest that mobile predators may often stabilize metacommunities by buffering variability that originates at the base of food webs. This finding illustrates that the trophic structure of metacommunities, which integrates variation in organismal body size and its correlates, should be considered when investigating ecological stability in natural systems. More broadly, our work advances the notion that temporal stability is an emergent property of ecosystems that may be threatened in complex ways by biodiversity loss and habitat fragmentation.

When investigating metacommunity dynamics, functional differences among species are often assumed to be as important as environmental differences between sites in determining beta-diversity. However, few studies have examined the influence of functional diversity on beta-diversity. We examine the relative importance of regional functional diversity partitioned by niche dimensions and environmental variation in structuring taxonomic beta-diversity of stream fishes using a large dataset of stream fish assemblages (hereafter, simply beta-diversity). We predicted that both functional diversity and environmental variation play a role in determining beta-diversity. We tested this prediction by modelling the patterns of stream fish beta-diversity as a function of environmental variation, functional diversity and gamma-richness across 10,220 sites for 329 fish species using a series of conceptual path models. Environmental variation consistently affected beta-diversity across all models, whereas functional diversity and gamma-richness influenced beta-diversity only in some models. We show that including relevant trait differences among species in path models can improve their ability to explain beta-diversity, suggesting that functional traits influence beta-diversity. The ability of path models to explain beta-diversity varied depending on the trait grouping included in the model, demonstrating that specific path models representing different niche dimensions can improve the ability of a model to explain beta-diversity. In addition, parsing traits into different niche dimensions revealed alternative patterns of functional diversity-beta-diversity relationships that otherwise would have been missed. The selection of relevant traits and linked niche dimensions is critical for detecting relationships between functional diversity and beta-diversity. Using traits associated with different niche dimensions allows for the identification of niche dimensions most strongly associated with species sorting and the detection of patterns missed by focusing on a single niche dimension. Determining the niche dimensions that influence beta-diversity could provide insights into the processes driving biodiversity and metacommunity dynamics, improving our ability to conserve or restore aquatic communities.

The organic carbon (C org ) stored in seagrass meadows is globally significant and could be relevant in strategies to mitigate increasing CO 2 concentration in the atmosphere. Most of that stored C org is in the soils that underlie the seagrasses. We explored how seagrass and soil characteristics vary among seagrass meadows across the geographic range of turtlegrass ( Thalassia testudinum ) with a goal of illuminating the processes controlling soil organic carbon (C org ) storage spanning 23° of latitude. Seagrass abundance (percent cover, biomass, and canopy height) varied by over an order of magnitude across sites, and we found high variability in soil characteristics, with C org ranging from 0.08 to 12.59% dry weight. Seagrass abundance was a good predictor of the C org stocks in surficial soils, and the relative importance of seagrass-derived soil C org increased as abundance increased. These relationships suggest that first-order estimates of surficial soil C org stocks can be made by measuring seagrass abundance and applying a linear transfer function. The relative availability of the nutrients N and P to support plant growth was also correlated with soil C org stocks. Stocks were lower at N-limited sites than at P-limited ones, but the importance of seagrass-derived organic matter to soil C org stocks was not a function of nutrient limitation status. This finding seemed at odds with our observation that labile standard substrates decomposed more slowly at N-limited than at P-limited sites, since even though decomposition rates were 55% lower at N-limited sites, less C org was accumulating in the soils. The dependence of C org stocks and decomposition rates on nutrient availability suggests that eutrophication is likely to exert a strong influence on carbon storage in seagrass meadows.

Secondary production is tissue formation by animals, regardless of its fate. While estimates of secondary production are central to understanding energy flow patterns and community dynamics in streams, they are still lacking in the literature. Methods of estimating secondary production range from following cohort abundance and biomass through time, to applying estimates of individual growth rates to biomass estimates. The exact procedure used depends on whether clear population cohort structures exist. Secondary production estimates used in conjunction with estimates of ecological efficiencies can serve to construct detailed energy flow food webs. Literature reviews show wide ranges in secondary production estimates among taxa, functional groups, habitats, and climate, with temperature, precipitation, and food availability being particularly important. Our understanding of drivers of secondary production, particularly at larger spatial scales, is hampered by an overall lack of studies, particularly in the tropics and logistically challenging habitats such as large rivers.

Human impacts, particularly nutrient pollution and land-use change, have caused significant declines in the quality and quantity of freshwater resources. Most global assessments have concentrated on species diversity and composition, but effects on the multifunctionality of streams and rivers remain unclear. Here, we analyse the most comprehensive compilation of stream ecosystem functions to date to provide an overview of the responses of nutrient uptake, leaf litter decomposition, ecosystem productivity, and food web complexity to six globally pervasive human stressors. We show that human stressors inhibited ecosystem functioning for most stressor-function pairs. Nitrate uptake efficiency was most affected and was inhibited by 347% due to agriculture. However, concomitant negative and positive effects were common even within a given stressor-function pair. Some part of this variability in effect direction could be explained by the structural heterogeneity of the landscape and latitudinal position of the streams. Ranking human stressors by their absolute effects on ecosystem multifunctionality revealed significant effects for all studied stressors, with wastewater effluents (194%), agriculture (148%), and urban land use (137%) having the strongest effects. Our results demonstrate that we are at risk of losing the functional backbone of streams and rivers if human stressors persist in contemporary intensity, and that freshwaters are losing critical ecosystem services that humans rely on. We advocate for more studies on the effects of multiple stressors on ecosystem multifunctionality to improve the functional understanding of human impacts. Finally, freshwater management must shift its focus toward an ecological function-based approach and needs to develop strategies for maintaining or restoring ecosystem functioning of streams and rivers.

Extreme events such as wildfires, hurricanes, and floods have increased in frequency and intensity. It is no longer a question of if, but rather when and where these events will occur (Stott 2016), with adverse impacts on essential ecosystem services including clean water, harvestable materials, and carbon sequestration. In some cases, extreme events such as wildfires may have positive impacts on populations and ecosystems. Managing these impacts requires understanding how environmental context as well as ecosystem and disturbance characteristics drive system responses (Hogan et al. 2020). However, funding for ecological extreme events research, such as through the US National Science Foundation's (NSF's) RAPID program, is typically reactive. Pre-event data, a RAPID prerequisite, are typically lacking or only sporadically available, and case studies of extreme events often arise from chance disturbances at existing long-term research sites. This reactive stochastic approach has seeded the literature with unplanned case studies describing individual events. While useful for meta-analyses (eg Patrick et al. 2022), such studies provide limited spatiotemporal inference and predictive capacity. Prioritizing the study of extreme events and empirically testing fundamental concepts in disturbance ecology is paramount (Aoki et al. 2022). Although NSF is the logical US funding agency for supporting this type of work, we – the authors – are unaware of any funding model at NSF (or other US federal agencies) for proactive, coordinated, hypothesis-driven research at the spatiotemporal scales needed to effectively study future natural events. Therefore, new funding mechanisms are necessary, ones that combine elements of existing programs in novel ways to provide researchers the flexibility to fill critical knowledge gaps. Advancing our understanding of the drivers and effects of extreme events on Earth's diverse ecosystems requires carefully planned tests of conceptual frameworks in the field. Such mechanistic, empirical studies will necessitate: (1) collection of pre-event data at locations ideal for testing a priori hypotheses; (2) data collection from and maintenance of experimental arrays over timescales sufficient to resolve seasonal and interannual dynamics, pre-event periods, stochastic disturbance events, and post-event recovery periods; and (3) replication across geographically distinct locations to ensure that studies include comparison of impacted and unimpacted sites. Networked experiments and monitoring over sufficient time periods are both critically important to this approach. Networked studies can provide powerful inference and are an efficient way to design investigations of future extreme events. Planning a disturbance study around a future event is inherently risky, as there is no guarantee that a study site will be disturbed during the study period. However, this risk can be greatly reduced. First, working at multiple, geographically distinct study sites increases the probability that one or more sites will be affected during a study period. Second, using historical disturbance frequency data to select locations with the highest chance of a disturbance occurring further increases the probability that a study site will be impacted. For example, there are three hurricane hotspots along the continental US coastline that could serve as sites for a sustained hurricane research network (Landsea and Franklin 2013): Cape Fear in North Carolina, southern Florida, and the central Louisiana coast (Figure 1). During any given five-year interval in the past 20 years there was a 100% chance that one or more sites within these three hotspots would be impacted by hurricanes (Figure 1). Thus, an eight-year networked study of these three high-risk areas with paired control sites in lower-risk areas would almost certainly capture at least one, and likely more, events within the first 5 years, followed by at least 3 years of recovery time. The approach described above can be applied to many types of extreme events, not just hurricanes. However, there is currently no funding solicitation that allows the combination of acceptable risk, funding amount, multi-site approach, and necessary time horizon required to support such a design. Within NSF's Division of Environmental Biology (DEB) and Biological Oceanography–Division of Ocean Sciences (BIO-OCE), there are many funding models. While aspects of the design described above can be found in individual solicitations, no single funding mechanism includes all the components necessary for proactive ecological investigations of extreme events. For instance, standard NSF grants allow for starting new experiments across a network of locations but have a maximum of 5 years of allowable funding, an insufficient time horizon for planning studies around future natural disturbance events. Furthermore, the riskiness of planning for an uncertain future event may prevent favorable review in this funding category. EAGER, a special solicitation type, allows for higher-risk projects but is limited to 2 years and has a modest budget (up to $300K) that precludes a networked or distributed approach. DEB's Long Term Research in Environmental Biology (LTREB) proposals cover 10-year periods (subject to a renewal after the initial 5 years) but are limited to $100,000 per year and require 6 years of pre-existing data, thereby excluding projects selecting new sites that are explicitly designed around disturbance questions. Existing long-term research and monitoring networks funded by NSF (eg National Ecological Observatory Network [NEON], Long Term Ecological Research [LTER]), as well as other federally funded programs like the National Oceanic and Atmospheric Administration's National Estuarine Research Reserve network, provide excellent data on spatiotemporal patterns in ecology, but these sites were not explicitly selected for this type of initiative (Aoki et al. 2022). Likewise, ad hoc experimental networks borne out of LTER (eg NutNet, DroughtNet) are not coordinated to capture complex cross-site responses within regions experiencing dynamic and repeated exposure to extreme events. Lastly, RAPID is designed to provide up to $200K in post-event evaluation in localized areas for 1 year after the event. While pre-event data are typically required, the reactive model effectively precludes the ability to provide funding to design and implement experiments in advance of disturbances. In addition, while multiple RAPID awards can be combined to increase the budget for comparison among multiple sites (Patrick et al. 2020), each proposal is evaluated independently, making networked projects difficult to fund. These limitations illustrate that while the reactive funding model has advanced our understanding of disturbance ecology and remains an essential funding tool, it is insufficient in several important ways. Importantly, existing programs fail to provide the combination of features required to address the need to advance our mechanistic understanding of extreme event ecology. In conclusion, a new funding program for extreme event research is needed. A program that supports the collection of new pre- and post-event data over 10-year periods from networks of frequently impacted sites would advance our understanding of how disturbances are (1) changing the structure and function of ecosystems worldwide and (2) interacting with other long-term environmental changes. Both are greatly needed in this era of unprecedented global change (Aoki et al. 2022), in which we need to rapidly adapt, and develop flexible and proactive funding programs. A shift to funding projects that embrace the uncertainty of the future will lead to important intellectual advancements and convergence in the arena of global change science. The work was supported by NSF Award 20003292. This manuscript is contribution number 4120 from the Virginia Institute of Marine Science and contribution number 1487 from the Institute of Environment at Florida International University. We thank D Wilcox and M Smith for assistance with figure creation and E Blood for reviewing the factual accuracy of our statements regarding features of NSF funding categories.

Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.