Continental-scale nutrient and contaminant delivery by Pacific salmon.

The movement of large amounts of nutrients by migrating animals has ecological benefits for recipient food webs that may be offset by co-transported contaminants. Salmon spawning migrations are archetypal of this process, carrying marine-derived materials to inland ecosystems where they stimulate local productivity but also enhance contaminant exposure. Pacific salmon abundance and biomass are higher now than in the last century, reflecting substantial shifts in community structure that probably altered nutrient versus contaminant delivery.

Mantled howler monkeys (Alouatta palliata) alter activity and spatial cohesion across a continuous forest and forest fragment in Costa Rica.

Habitat loss due to deforestation is a primary threat to global biodiversity. Clearing tropical rainforests for agriculture or development leads to forest fragmentation. Forest fragments contain fewer large trees and provide lower food availability for primates compared to continuous forests.

Density declines, richness increases, and composition shifts in stream macroinvertebrates.

Documenting trends of stream macroinvertebrate biodiversity is challenging because biomonitoring often has limited spatial, temporal, and taxonomic scopes. We analyzed biodiversity and composition of assemblages of >500 genera, spanning 27 years, and 6131 stream sites across forested, grassland, urban, and agricultural land uses throughout the United States. In this dataset, macroinvertebrate density declined by 11% and richness increased by 12.

Behavioral responses to riparian and anthropogenic edge effects in mantled howler monkeys (Alouatta palliata) in a disturbed riverine forest.

Fragmented forests contain natural edges, including riparian zones, and anthropogenic edges. Edges generally have lower plant density and fewer large trees than forest interior. Riparian edges, however, contain gap-specialist trees yielding leaves with high protein content, providing primates with important resources.

In search of microbial indicator taxa: shifts in stream bacterial communities along an urbanization gradient.

A majority of environmental studies describe microbiomes at coarse scales of taxonomic resolution (bacterial community, phylum), ignoring key ecological knowledge gained from finer-scales and microbial indicator taxa. Here, we characterized the distribution of 940 bacterial taxa from 41 streams along an urbanization gradient (0%-83% developed watershed area) in the Raleigh-Durham area of North Carolina (USA). Using statistical approaches derived from macro-organismal ecology, we found that more bacterial taxa were classified as intolerant than as tolerant to increasing watershed urbanization (143 vs 48 OTUs), and we identified a threshold of 12.

The influence of anthropogenic edge effects on primate populations and their habitat in a fragmented rainforest in Costa Rica.

When a forest is fragmented, this increases the amount of forest edge relative to the interior. Edge effects can lead to loss of animal and plant species and decreased plant biomass near forest edges. We examined the influence of an anthropogenic forest edge comprising cattle pasture, coconut plantations, and human settlement on the mantled howler (Alouatta palliata), white-faced capuchin (Cebus capucinus), Central American spider monkey (Ateles geoffroyi), and plant populations at La Suerte Biological Research Station (LSBRS), Costa Rica.

Bacterial community responses to a gradient of alkaline mountaintop mine drainage in Central Appalachian streams.

Microbial community composition and diversity change along chemical gradients, leading to the expectation that microbial community information might provide new gradient characterizations. Here we examine stream bacteria composition and diversity along a strong chemical gradient in Central Appalachian streams. Coal mining in the region generates alkaline mine drainage (AlkMD), causing dramatic increases in conductivity, alkalinity, sulfate and metals sufficient to degrade stream macrobiota communities throughout the ecoregion.

A study of the effect of physical and chemical stressors on biological integrity within the San Diego hydrologic region.

Environmental agencies across the United States have searched for adequate methods to assess anthropogenic impacts on the environment. Biological assessments, which compare the taxonomic composition of an aquatic assemblage to relevant biocriteria, have surfaced as an effective method to assess the ecological integrity of US waterbodies. In this study, bioassessment data were collected and analyzed in conjunction with physical habitat and chemical stressor data for streams and rivers within the San Diego basin from 1998 through 2005.