Ecological Applications最新文献

While it is widely recognized that reduced river-floodplain connectivity has contributed to the decline of biodiversity in floodplain rivers, surprisingly few studies have quantified the relationship between connectivity, pool persistence, and fish assemblage structure to the level required to generate measurable targets for management. The task is further complicated by the inherent complexity of accurately describing fish assemblages. We maximized our capacity to describe unbiased hydrology–fish relationships by sampling fish assemblages in floodplain pools with a variety of connection histories (60 sampling events), and by using a hierarchical multispecies occupancy model that accounts for changes in sampling design and species detection. Our study was conducted in a tropical wet-dry river threatened by water resource development and elevated temperatures associated with climate change, the Fitzroy River (Western Australia). Our results revealed that wet season (river-floodplain connectivity) and dry season (pool persistence) components of the hydrological cycle influenced fish occurrence in floodplain pools. Pools that were connected to the river by short distances were substantially more species rich than distal pools. This effect was strong at distances <2000 m but negligible at distances greater than 3000 m. Species richness in floodplain pools increased when wet season connection to the river lasted more than 25 days, and when river stage height exceeded 6 m. Prolonged connection to the river (up to 90 days) during overbank flooding (river stage height >11 m) maximized fish species richness in floodplain pools. Dry season components of the hydrological cycle also influenced fish assemblage structure, with pools that persisted during the preceding dry season twice as species rich as those that dried. Our model revealed that sampling gear influenced species detectability, indicating that accounting for variable detection is critical when assessing fish assemblage structure. Given that large flood events are less likely to be impacted by water take, we recommend that managers seeking to maintain floodplain fish diversity ensure that water resource development does not negatively impact pool persistence during the dry season.

Seamounts are unique habitats in the deep sea facing anthropogenic stressors, including future deep-sea mining. To conserve patchy marine habitats such as seamounts, it is critical to design conservation area networks that maintain connectivity by larval dispersal. This study conducted biophysical modeling to quantify larval dispersal among 18 seamounts in the Northwest Pacific, within the scope of a regional environmental management plan for mining under development by the International Seabed Authority. Seamounts formed a single dispersal network, but excluding seamounts with mining potential showed the network could become fragmented. Two seamounts whose mining potential was relinquished in 2024 were identified as key stepping stones, suggesting that environmental conservation at these two seamounts can contribute to maintaining a single dispersal network. Predominant eastward or westward currents, likely related to the North Equatorial Intermediate Current, made the upstream, distant seamounts vital larval sources. Trajectories of Argo floats and gene flows of amphipods provided physical and biological support for the modeled dispersal. This study highlights the potential for effective conservation area placement based on a seamount network connected by upstream-based larval dispersal.

River-floodplain ecosystems near urban centers are heavily engineered for flood protection and water delivery, which has led to a loss of lateral hydrologic connectivity between rivers and their floodplains. This study has two objectives: (1) Does increased lateral connectivity resulting from floodplain inundation increase chlorophyll a biomass? (2) Does that bump in chlorophyll a get transported downstream? The San Francisco Estuary in California, USA, has a robust and long-term monitoring network for water quality. We integrated water temperature, chlorophyll a, flow, and floodplain inundation data from multiple sources creating a continuous dataset with fine temporal resolution spanning two decades. We used a consistent generalized additive mixed model structure across three regions: the floodplain, the mainstem of the river adjacent to the floodplain, and the section of the river downstream from both the floodplain and mainstem. We found that when the floodplain is not inundated, chlorophyll a biomass is mainly influenced by water temperature. However, when the floodplain is laterally connected during periods of inundation, water spreads over a larger surface area in the floodplain, flows decrease and water temperatures increase creating favorable conditions for chlorophyll a production. High flows during the flood pulse quickly transport chlorophyll a downstream, flushing the estuary with food. Under optimal conditions, tidal mixing in the downstream portion of the estuary can continue to boost chlorophyll a biomass in the system even after the flood waters have retreated. This study can guide the design, enhancement, and management of water conveyance structures to meet environmental flow regulations and to benefit the estuarine food web.

Quantifying the impact of lower trophic level species abundance on higher trophic level predators (and vice versa) is critical for understanding marine ecosystem dynamics and for implementing ecosystem-based management. Trophic ecosystem models generally predict a tight coupling between prey and fish predators, such that higher abundance of lower trophic species increases the abundance of higher trophic level predators. This assumes that predator feeding rates are limited by prey availability to some degree. Despite being a key component of predator–prey interactions and multispecies fisheries management, relatively few studies have assessed the impacts of prey availability on predation patterns of mobile, generalist fish predators using spatiotemporal models and local-scale stomach content, predator, and prey data. In this study, we explore the association between local density of key prey and predator stomach contents, and predator–prey spatiotemporal overlap and predation indices, using the Baltic Sea as a case study. We use three decades of spatially resolved biomass and stomach content data on Atlantic cod (Gadus morhua), and biomass data on three of its key prey: herring (Clupea harengus), the isopod Saduria entomon, and sprat (Sprattus sprattus). Using geostatistical generalized linear mixed-effects models fitted to relative biomass density and prey-mass-per-predator-mass, we estimate spatiotemporal trends and annual indices of biomass- weighted and area-expanded per-capita and population-level predation, predator–prey overlap, and the correlation between these indices. Range shifts have resulted in reduced predator–prey overlap over time, which is now the lowest in three decades. For Saduria, we find an association between prey availability and stomach contents, but not for herring or sprat. Similarly, only in Saduria do we find a positive correlation between population-level predation indices and the spatiotemporal overlap. Although behavioral interactions with pelagic prey are challenging to infer from stomach content and acoustic data due to high mobility leading to fine-scale spatiotemporal mismatch, the weak connection with local-scale availability, and low correlation between population-level predation and spatial overlap, could imply weaker coupling between pelagic prey and cod than previously thought. These findings provide key information on the strength of species interactions, which is crucial for the continued development of multispecies models and ecosystem-based fisheries management.

Across much of the semiarid conifer forests of western North America (“dry conifer forests”), the dominant tree species are non-serotinous, lack soil seedbanks, and rarely disperse seeds much farther than 100 m, so tree regeneration in large, high-severity burned patches is expected to be highly seed-limited. Conifer seedlings do, however, sometimes establish at high densities deep within high-severity patches in these forests, implying that seeds can sometimes survive intense wildfire even when all overstory trees die. Does seed survival in the canopies of non-serotinous trees provide an unexpected source of forest resilience? To answer this question, we surveyed tree survival, fire severity, and seedling abundance across two very large wildfires in the first year after fire. Several of the study species had a good seed cone production year at the time of the fires. We stratified many of our plots deep within high-severity patches far from surviving trees, where existing models predict regeneration failure due to lack of viable seeds. Contrary to such expectations, we found that conifer seedling densities in these areas were generally far greater than needed to replace the fire-killed stand and sometimes approached seedling densities observed near surviving trees. Seedling densities in high-severity areas far from surviving trees correlated negatively with local burn intensity (canopy foliage consumption), supporting the idea that the seeds originated locally and highlighting a critical driver of post-fire recovery that is easily missed by traditional surveys conducted >2 years following fire. Seedling density was also strongly associated with burn date, suggesting that persistence of viable canopy seeds depends on synchrony between wildfire and cone ripening dates. Together, our results demonstrate that under the right conditions, canopy seed survival can lead to dense seedling establishment across large severely burned areas and may substantially support the resilience of dry conifer forests to the uncharacteristically severe fires that are becoming increasingly prevalent in this system.

Understanding the mechanisms that maintain the productivity of grassland communities is crucial for ecosystems to provide functions and services under climate change and for developing grassland management and restoration strategies. Plant traits, such as phenological (timing) and morphological (size) traits, are essential for predicting ecosystem function under climate change. However, how plant traits respond to warming and precipitation change and their combined consequences on ecosystem function (e.g., biomass) remain poorly understood. Here, we conducted a 5-year field warming and precipitation change experiment in an alpine meadow on the Tibetan Plateau, and measured six plant phenological and morphological traits of 10 common species to research how functional traits regulate plant biomass under warming and precipitation change. Warming rather than precipitation advanced plant leaf emergence and lengthened the growing season and reduced mean plant height for sedges and forbs, while it reduced leaf area of sedges and grasses. Moreover, the negative effects of warming-induced reductions in plant height and leaf area on sedge biomass were offset by the positive effects of advanced leaf emergence, which did not completely mitigate the negative effects of low plant height on forb biomass production. Our results suggest that the negative effect of warming on the biomass of sedges and forbs through reduced plant size will be partially mitigated by the compensatory effect of advanced leaf emergence. This finding further emphasizes that the crucial and opposing roles of phenological and morphological traits should be considered when assessing biomass production and sustainable services in alpine grasslands under climate change.

Natural recovery of degraded coral reefs is constrained by low larval recruitment, limiting restoration at ecologically meaningful scales. While propagule-based approaches have proven effective in plant-dominated systems, scaling larval restoration for sessile invertebrates like corals remains challenging. Traditional coral larval methods rely on net enclosures, restricting impact to small areas (<75 m²). We developed and tested a modular, passive larval delivery system—the larval seedbox—to overcome these spatial constraints. Each unit (600 × 500 × 300 mm; 11 kg) enables delayed release of competent larvae near the benthos, enhancing substrate encounter rates over broader areas. At Lizard Island (Great Barrier Reef), five seedboxes delivered ~14 million larvae across ~2 ha of degraded reef. Larval release coincided with slack currents to facilitate local retention and subsequent dispersal. Settlement was assessed on 234 tiles placed in concentric arrays around each seedbox. After 48 h, 85% of tiles had settlers (up to 1041 per tile), with mean densities 24 times greater than background levels. Enhanced settlement was directly quantified across ~470 m², with spatial modeling estimating >3000 m² via tidally driven dispersal. The larval seedbox enables unrestrained, scalable coral larval seeding and represents a practical advance toward broad-scale reef restoration.

Early studies and theory suggested that complex landscapes harboring remnants of natural land should support natural enemy populations and reduce pest buildup in adjacent crops, whereas landscapes interspersed with urban land often provide alternate host plants of crop pests, facilitating pest spillover and amplifying pest pressure. However, recent meta-analyses have demonstrated that both pest and beneficial agricultural arthropods respond inconsistently to surrounding landscapes. These meta-analyses relied on studies of one to two pests per crop across many different crop and landscape contexts, which limits inferences about how growers might design landscapes for effective control of a full suite of pests attacking a given crop. Here, we harnessed an ecoinformatics dataset from California Citrus to examine the effects of surrounding natural and urban land on the densities of a complete suite of seven major pest species (6489 observations) and one beneficial predator (346 observations). We also explored landscape effects on pesticide use and fruit production. Despite restricting this analysis to data collected in the same region and cropping system, we found that arthropods still exhibited mixed responses to surrounding landscapes. Among the eight Citrus-associated arthropods surveyed, greater amounts of nearby natural land resulted in two beneficial outcomes for farmers (lower pest densities or fewer pesticide applications targeting that pest), three adverse outcomes, and three neutral outcomes. Similarly, greater amounts of urban land resulted in two beneficial outcomes, four adverse outcomes, and two neutral outcomes for farmers. Our economic analysis demonstrated that Citrus groves with more nearby natural land resulted in increased total pesticide use and reduced total fruit yield. More urban land resulted in reduced total pesticide use and no effect on total fruit yield. Neither land use type significantly impacted fruit quality. Taken altogether, our results do not demonstrate clear support for the retention of natural habitat or minimization of urban land near cropland solely for the purpose of enhancing conservation biocontrol. Nonetheless, the value of natural land extends far beyond its utility for conservation biocontrol, and agricultural landscapes must still be managed to strike a balance between crop production and the preservation of biodiversity and ecosystem function.

Movement is essential for animal life and significantly influences community dynamics. Landscape-scale disturbances, such as mining, alter habitat structure, introducing new stressors that can severely disrupt animal movement. Understanding how landscape modification impacts animal movement and landscape connectivity is vital for effective conservation in the Anthropocene. Here, we used movement simulations and landscape scenarios to evaluate how mining influences movement, using an endangered mesopredator as a focal species. We aimed to determine the effects of different configurations of mining on the movement costs, habitat accessibility, and landscape connectivity of this species. We used GPS data collected from a mining landscape in the Pilbara region of Western Australia to assess temporally dynamic habitat selection. This informed movement simulations across four landscape scenarios: current mining, dispersed mining, aggregated mining, and non-mining. We compared animal movements, energetic costs, and landscape connectivity across all landscape scenarios. The presence of mining habitats increased energetic movement costs through unfavorable habitats and led to significant changes in landscape connectivity. For example, simulated movements visited fewer favorable habitat patches in mining landscapes and required more steps between them. Mining configuration affected movement differently, with current mining conditions having the greatest impact on movement, increasing simulated home ranges and funneling movement through unfavorable habitats more than the other landscapes. Our study highlights the influence of disturbance configuration and altered habitat structure on animal movement. It also emphasizes that effective management and development planning must consider impacts on animal movement and landscape connectivity.