Urbanization Drives Riparian Scavenging Avian Communities and Salmon Carcass Consumption

This report presents an assessment of the natural area value of eight Aquatic Natural Areas (ANAs) and seven Aquatic Reference Areas (ARAs) on the Oak Ridge Reservation (ORR) in Anderson and Roane Counties in east Tennessee. It follows a previous study in 2009 that analyzed and evaluated terrestrial natural areas on the Reservation. The purpose of both studies was to evaluate and rank those specially designated areas on the Reservation that contain sensitive species, special habitats, and natural area value. Natural areas receive special protections through established statutes, regulations, and policies. The ORR contains 33,542 acres (13,574 ha) administered by the Department of Energy. The surface waters of the Reservation range from 1st-order to 5th-order streams, but the majority of the streams recognized as ANAs and ARAs are 1st- and 2nd-order streams. East Fork Poplar Creek is a 4th-order stream and the largest watershed that drains Reservation lands. All the waters of the Reservation eventually reach the Clinch River on the southern and western boundaries of the ORR. All available information was collected, synthesized, and evaluated. Field observations were made to support and supplement the available information. Geographic information system mapping techniques were used to develop several quantitative attributes about the study areas. Narrative descriptions of each ANA and ARA and tables of numerical data were prepared. Criteria for assessment and evaluation were developed, and eight categories of factors were devised to produce a ranking system. The evaluation factors used in the ranking system were: (A) size of area, (B) percentage of watershed protected, (C) taxa present with protected status, (D) overall biotic diversity, (E) stream features, (F) water quality and use support ratings, (G) disturbance regime, and (H) other factors. Each factor was evaluated on a 5-point ranking scale (0-4), and each area received a composite score, where 32 was the maximum score possible. A highly ranked ANA or ARA is one that is large in size compared to other areas, includes a greater proportion of the watershed within Reservation boundaries, contains a number of status taxa at high densities, exhibits a high overall biodiversity, has very good or excellent habitat and water quality, is well protected and isolated from disturbances, and shows several other characteristics that contribute to natural area value. In this report, the term 'natural area' is loosely defined as a terrestrial or aquatic system that exhibits, or is thought to exhibit, high natural integrity and other significant natural values. The purpose of the present study is to evaluate and rank the currently recognized Aquatic Natural Areas (ANAs) and Aquatic Reference Areas (ARAs) on the Oak Ridge Reservation (ORR) for their natural area value. A previous study (Baranski 2009) analyzed, evaluated, and ranked terrestrial areas (Natural Areas [NAs], Reference Areas [RAs], and Cooperative Management Areas [CMAs]) on the ORR for natural area value, and a precise methodology for natural area evaluation was developed. The present study is intended to be a complement and companion to the terrestrial area study and attempts to employ a similar methodology for aquatic areas so that aquatic and terrestrial areas can be compared on a similar scale. This study specifically develops criteria for assessing the ecological, biodiversity, and natural area importance and significance of aquatic systems on the Reservation in a relevant and consistent manner. The information can be integrated into the Tennessee Natural Heritage Program (http://tn.gov/environment/na/nhp.shtml) system and applied to potential new aquatic areas. Further, the information will be useful in planning, management, and protection efforts on the ORR.

Pacific pink salmon (Oncorhynchus gorbuscha) invasions, thought to originate from populations introduced and established in Russia, occurred along the Norwegian coast in 2017 and 2019. Despite several thousand pink salmon entering and establishing in northern Norwegian rivers, current understanding of the ecological effect of the species in northern Europe is limited. Scavengers feeding on pacific salmon carcasses are important vectors for the transport of marine derived energy and nutrients to terrestrial ecosystems in the Pacific Northwest, North America, where the salmon naturally occur. However the role of terrestrial and aquatic scavengers in the consumption and removal of pink salmon beyond the salmon’s native range is unknown. This study has identified terrestrial and sub-aquatic vertebrate scavengers on pink salmon carcasses in a sub-arctic river in northern Norway. Avian scavengers filmed by a camera placed near sites baited with pink salmon carcasses included the Eurasian magpie (Pica pica), hooded crow (Corvus cornix), common raven (Corvus corax), the European herring gull (Larus argentatus), redwing (Turdus iliacus) and goosander (Mergus merganser). However, the largest carcass weight was removed by red foxes (Vulpes vulpes). Carcasses entering Vesterelv River in 2019 were estimated to provide energy and nutrients to the river ecosystem an order of magnitude lower than in the Pacific Northwest. This study provides some of the first information in northern Europe on the mechanisms and quantification of energy and nutrient transfer from the ocean to riparian environments via introduced Pacific pink salmon. Results help to begin to determine the ecological effect of pink salmon and the development of appropriate management strategies.

Effects of spring prescribed burning and wildfires on watershed nitrogen dynamics of central Idaho headwater areas

The effects of salmon carcasses on dissolved nutrients, epilithic production, leaf decomposition rates, and aquatic invertebrates were examined using 10‐m‐long artificial channels fed by an adjacent natural stream in Hokkaido, northern Japan. Bags containing maple leaf litter were placed in nine channels, each of which was assigned to one of three treatments with three replicates, for 6 weeks in fall 2002. The three treatments were: (1) salmon carcasses+invertebrates, (2) invertebrates only, and (3) control (no salmon carcasses or invertebrates added). Nutrient concentrations, biomass of epilithic algae (chlorophyll), leaf weight loss, abundance and biomass of invertebrates in the leaf packs were compared among the three treatments at 14, 27, and 40 days after the beginning of the experiment. The NH 4 + in stream water and chlorophyll concentrations of epilithic algae were higher in the salmon treatment than the other treatments, and the maple leaves decomposed faster in the salmon treatment than in the other treatments. Moreover, the N content of the leaves was highest and the C/N ratio was lowest in the salmon treatment, although not significantly so. The abundance and biomass of the dominant leaf‐shredding invertebrate Goerodes satoi did not differ between the first two treatments. However, the stable N isotope ratio in G. satoi was nearly 3‰ higher in the salmon treatment, suggesting that around 20% of salmon‐derived N was taken up by this shredder. Our results indicate that salmon carcasses affect stream ecosystems directly by enhancing primary production, indirectly by accelerating woody leaf decomposition, and finally by incorporating into the food web primary consumers that utilize fertilized woody leaves.

Spatial distribution patterns and drivers of above- and below- biomass in Chinese terrestrial ecosystems

Antibiotics in Aquatic and Terrestrial Ecosystems

Feeding niches of riverine and coastal mink (Mustela vison) in southeast Alaska differ in prey composition and abundance and diving medium during spring and summer. In autumn, however, the upstream migration of spawning Pacific salmon (Oncorhynchus sp.) creates a pulse of food for mink. We hypothesized that diets of coastal and riverine mink, and therefore their stable isotope ratios (δ13C, δ15N), would differ significantly during periods when salmon were absent, but that salmon carcasses would constitute a large portion of the diet of both groups during the salmon spawning season. Stable isotope analyses of clotted blood cells from 24 live-captured mink and muscle tissue from 25 mink carcasses were used to indicate the composition of diets of individual mink in 1992 and 1993. These isotope values were then compared with stable isotope ratios of prey, using a multiple-source mixing model. Our results indicate that riverine mink depended on salmon (carcasses and fry), with little seasonal or individual variation, whereas coastal mink relied on intertidal organisms in spring and summer, with measurable (<25%) consumption of salmon carcasses when they became available in autumn. Coastal and riverine mink in southeast Alaska differ strongly in their diets in spring and summer, with both groups relying on the abundant salmon carcasses during autumn.

Biodiversity at many scales (functional group, species, genetic) can result in emergent ecological patterns. Here we explore the influence of tree genotypic variation and diversity on in-stream ecosystem processes and aquatic communities. We test whether genetically diverse inputs of leaf litter interact with a keystone organism, anadromous salmon, to influence in-stream ecosystem function. We used reach-level manipulation of salmon carcasses and leaf litter bags to examine how nutrient inputs interact with genetic variation in leaf litter decomposition. Genotypic variation in black cottonwood (Populus balsamifera ssp. trichocarpa) significantly influenced leaf litter chemistry, litter mass loss, and fungal biomass, but these variables were only weakly influenced by salmon carcass presence or a genotype × salmon (G × E) interaction. Mixtures of genotypes tended to demonstrate antagonistic effects (slower than expected decomposition) in the absence of salmon, but synergistic effects (faster than expected decomposition) when salmon were present. Our findings suggest that the influence of plant genotypic variation in linking aquatic and terrestrial ecosystems may be altered and in some cases intensified in the presence of a keystone vertebrate species.

Pacific salmon and other anadromous salmonids represent a major vector for transporting marine nutrients across ecosystem boundaries (i.e., from marine to freshwater and terrestrial ecosystems). Salmon carcasses provide nutrients and energy to biota within aquatic and terrestrial ecosystems through various pathways. In this paper we review and synthesize the growing number of studies documenting this process in different localities. We also discuss the implications for maintaining the nutrient feedback system. Our findings show that future management will need to view spawning salmon and their carcasses as important habitat components for sustaining the production of fish as well as other salmon-dependent species within watersheds.

Identifying ecosystem service functions, clarifying the spatiotemporal trade-offs and synergies of terrestrial ecosystem services and their driving mechanisms, and exploring differentiated ecological functional zoning are crucial steps in achieving healthy regional ecosystem management, and are conducive to developing diversified ecological restoration strategies, establishing a robust cross-regional collaborative management mechanism, implementing differentiated ecological management strategies, and contributing to the construction of a Beautiful China. This paper, based on the InVEST model, Pearson correlation, GeoDetector, and Spatiotemporal Geographically Weighted Regression models, constructs a spatial quantification model of the trade-offs and synergies among five key ecosystem service functions—habitat quality, soil retention, water conservation, food supply, and carbon sequestration—of China’s terrestrial ecosystems from 2000 to 2020. It explores the influencing factors of terrestrial ecosystem services in China and their spatiotemporal heterogeneity, thereby investigating the future strategies for ecological functional zoning and management of China’s national land space. The results indicate that: (1) during 2000–2020, China’s food supply and soil conservation have increased. However, the habitat quality, water conservation, and carbon sequestration have decreased. (2) Significant spatial and temporal heterogeneities exist in the key ecosystem services of China’s terrestrial ecosystems. (3) Natural, economic, and social factors all impact China’s terrestrial key ecosystem services. Among them, slope, annual average precipitation, land development intensity, and vegetation coverage are the main influencing factors, and different factors exhibit significant spatial heterogeneity. (4) Significant trade-offs/synergy effects among critical terrestrial ecosystem services exist in China. (5) China’s national territory is divided into four ecological protection functional zones: ecological restoration areas, ecological control areas, resilient development areas, and ecological conservation areas, and explores differentiated zoning optimization control paths.

Mechanisms of phosphorus release from coastal sediments driven by organic matter enrichment at high nitrogen concentrations.

Linkages of stoichiometric imbalances to soil microbial respiration with increasing nitrogen addition: Evidence from a long-term grassland experiment

Potential roles of arginine-vasotocin in the regulation of aggressive behavior in the mudskipper (Periophthalmus modestus)

<p>The propagation of environmental stressors from water (source) to land (sink) in aquatic-terrestrial meta-ecosystems, has not been intensively investigated. The other way around has been in the focus of linking terrestrial and aquatic domains. To start bridging that gap, SYSTEMLINK, a DFG Research Training Group, addresses the bottom-up and top-down mediated interactions in terrestrial ecosystems, which origin from anthropogenic impairments on aquatic ecosystems. Micropollutants (fungicides and insecticides) as well as invasive species (riparian plants and invertebrates) are considered as crucial forms of multiple stressors in disturbed aquatic ecosystems. SYSTEMLINK will examine the general hypotheses that 1) invasive invertebrates and insecticide exposure and 2) invasive riparian plants and fungicide exposure cause top-down and bottom-up mediated responses in terrestrial ecosystems, respectively. Collaborative experiments in replicated outdoor aquatic-terrestrial mesocosms (site-scale) amended by joint pot experiments (batch-scale), field studies (landscape-scale), and modelling are used to test these general and several more specific hypotheses. The experimental setups will all represent a multi-stress environment and will be derived from the landscape scale. The regular combination of several scales will allow to overcome scale-specific limitations and to ensure both cause-effect quantification and the environmental relevance of the results. Ultimately, SYSTEMLINK thrives to increase our knowledge on effect translation across ecosystem boundaries. By combining biological subsidies and biogeochemical fluxes we will be able to quantify their relative importance. Furthermore, we will closely incorporate the often separated aquatic and terrestrial research areas.</p>

The latitudinal and elevational patterns of species richness of resident and migrant birds have been of interest to researchers over the past few decades, and various hypotheses have been proposed to explain the factors that may affect these patterns. This study aimed to shed light on the elevational distribution patterns of resident and migrant bird species richness by examining biotic and abiotic factors such as climate, and habitat heterogeneity using a piecewise structural equation model (pSEM). The overall pattern of resident species richness showed a decreasing trend with increasing elevation, whereas that of migrant species richness showed an increasing trend. The mid-peak pattern of species richness was affected by a combination of resident and migrant species and not by either resident or migrant species. Our results showed that resident species were distributed in lower elevation regions with higher mean spring temperatures, whereas migrant species were found in higher elevation regions with lower mean spring temperatures and higher overstory vegetation coverage. Although high elevation conditions might adversely affect the reproduction of migrant birds, higher overstory vegetation coverage at high elevations seemed to compensate for this by providing a better nesting and roosting environment. Despite the significance of habitat diversity and understory vegetation coverage in univariate linear regression models, multiple regression models of the interconnection of ecological processes demonstrated that mean spring temperature and overstory vegetation coverage were more explanatory than other variables.