312 research outputs found
A Comparison of the Experiences of Economic Adaptation and Integration for Refugees and Asylum Seekers in Maine
The migration of refugees and asylum seekers affects them and the communities where they resettle, as people from different backgrounds and cultures come together. In the United States, the federally funded refugee resettlement program supports refugees with welfare benefits, case management, and other services to assist with integration. However, no such federal program exists for asylum seekers, who are considered displaced people, but who have not received immigration status as refugees. This project sought to answer the question: How is the experience of supporting oneself different and similar for refugees and asylum seekers, in the context of Maine?
Research involved a literature review on the use of social capital within immigrant groups, an analysis of recent local newspaper articles on the migration of asylum seekers to Maine, and eleven semi-structured key informant interviews with asylees, refugees, community leaders, and service providers. It appeared that their communities were an important source of information, temporary housing, and served as a forum from which to celebrate culture, for both refugees and asylum seekers, though perhaps more so for asylum seekers. Many refugees and asylum seekers shared the challenges of integrating into a new culture and seeking better opportunities after their credentials were devalued. This study proposes that NGOs develop mentoring programs for asylum seekers modeled on the mentoring programs organized by Catholic Charities Maine Refugee and Immigration Services. These would build bridges of understanding between refugees and members of the receiving community
Comparison of fatty acids and elemental nutrients in periphyton, invertebrates, and cutthroat trout (Oncorhyncus clarki) in conifer and alder streams of western Washington state
This is the portpriint version of the article. The original publication is available at www.springerlink.comOrganism growth and reproduction are often limited by nutrient availability in freshwater ecosystems where, in some cases, food webs are primarily supported by allochthonous organic matter. Therefore, we hypothesized that the composition of riparian vegetation would influence the variability of N, P and fatty acid content of in-stream consumers. Specifically, we predicted that organisms living in alder streams would have higher levels of N, P, and polyunsaturated fatty acids than organisms in coniferous streams. To determine this, we sampled fresh and aged leaf litter, periphyton, invertebrates, and cutthroat trout (Oncorhynchus clarki) from 6 streams in western Washington state: 3 streams had high densities of nitrogen-fixing red alder (Alnus rubra) in the riparian zone, whereas 3 had high densities of conifers. We found fresh alder litter had twice the total polyunsaturated fatty acid concentrations of hemlock vegetation while there were few statistical differences among aged alder and aged hemlock vegetation. Multidimensional plots showed fatty acid profiles were unique to vegetation and fish while periphyton and invertebrates shared the same multidimensional space. We used a mixed model to determine the relative importance of vegetation type (fixed factor: conifer or alder), trophic levels (fixed factor: periphyton, primary consumer, or fish) and streams (random factor) on individual fatty acid concentrations. Total polyunsaturated fatty acids, 16:0, 20:1, 20:3n6 and total n3 were the only fatty acids influenced by stream vegetation (vegetation + stream model or full model. 67% of the fatty acids were best supported by the trophic +stream model. Nitrogen, P, Ca, Fe, C:N, N:P and C:N:P were all best supported by the trophic level + stream model and Zn was the only nutrient supported best by the full model. Correlations of n3 and n6 fatty acid concentrations between periphyton and primary consumers, and primary consumers with trout indicated several fatty acid metrics, such as n3:n6, showed food resources may affect relative fatty acid abundances of consumers. Although vegetation type did not influence relative fatty acids of stream organisms, the importance of trophic level likely indicates organisms have different physical requirements for fatty acids. The significance of a random factor, ‘stream,’ suggests that the relative abundances of fatty acids in periphyton, invertebrates and trout are more related than similar organisms from another stream
Changing forests-changing streams: Riparian forest stand development and ecosystem function in temperate headwaters
Light availability influences temperature, primary production, nutrient dynamics, and secondary production in aquatic ecosystems. In forested freshwater ecosystems, shading by streamside (riparian) vegetation is a dominant control on light flux and represents an important interaction at the aquatic-terrestrial interface. Changes in forest structure over time, particularly tree mortality processes that gradually increase light penetration through maturing forest canopies, are likely to influence stream light fluxes and associated ecosystem functions. We provide a set of conceptual models describing how stream light dynamics change with the development of complex canopy structure and how changes in light availability are likely to affect stream ecosystem processes. Shortly after a stand-replacing event, light flux to the stream is high, but light fluxes decline as canopies reestablish and close. Tree density, the degree of understory growth, patterns of tree mortality, and small-scale disturbances interact as drivers of multiple pathways of forest structural development. Changes in canopy structure will, in turn, influence stream light, which is expected to impact primary production and stream nutrient dynamics as well as the amount of autochthonous carbon supporting aquatic food webs. Ultimately, these conceptual models stress the importance of recovery from historic forest disturbances as well as future forest change as important factors influencing the long-term trajectories of ecosystem processes in headwaters
Abundance and body condition of sculpin (Cottus spp.) in a small forest stream following recolonization by juvenile Coho Salmon (Oncorynchus kisutch)
Recolonization by native species following reintroduction can affect resident species through a variety of processes. We examined the effects of natural recolonization by coho salmon Oncorhynchus kisutch on sculpin (Cottus rhotus and Cottus gulosus), small benthic fishes, in a small forest stream in Western Washington, USA. Provision fish passage around a small dam allowed coho access to habitat, which had been inaccessible for over 100 years. We found that density (g m−2 and number m−2) was unchanged, and body condition (the slope of the relationship between length and weight) of sculpin tended to increase from before relative to a 5-year period following recolonization. The proportion of sculpin comprising the total fish assemblage decreased after coho colonization relative to before but remained stable for a 5-year period after coho reintroduction, whereas coho density increased over fivefold. Additionally, we used Akaike's information criteria to evaluate the relative importance of physical and biological variables to predict sculpin density in pool habitats during the initial coho recolonization period. Physical microhabitat variables had little support for predicting sculpin density, whereas there was a significant support for stream temperature; cutthroat trout (Oncorhynchus clarkii) density and year were the most important predictors of sculpin density. Coho density was not significant in any model. Our results indicate coho introduction and subsequent recolonization have to date had minimal individual or population level effects on sculpin, therefore demonstrating that species reintroductions into their native range can have no measurable effect on resident organisms. Published 2013. This article is a U.S. Government work and is in the public domain in the USA
Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment
This is an open access article. You can find it online by following this link: http://www.esajournals.org/doi/pdf/10.1890/ES13-00269.1An experiment and a mark-recapture field study of juvenile coho salmon (Oncorhynchus
kisutch) were conducted to identify controls of key energy flow chains in river food webs. In the small-scale
experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as
small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha) on nutrients, algae,
invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural
variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer
growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels
resulted in strong bottom-up effects on select invertebrates including increased population biomass of
chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We
link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.33
higher and coho consumption of these animals 33 higher in salmon-subsidized channels. PHS in
experimental channels was associated with reduced algal biomass, potentially in response to increased
invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was
negatively related to PHS and total fish density and positively related to Diptera drift biomass; however,
the effects of fish density and drift biomass on coho growth were relatively weak. The field study also
indicated that prey resource availability and coho growth were associated with differences in canopy cover,
with prey biomass and coho growth 2–43higher in reaches receiving more sunlight. As in the experiment,
coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that
these taxa and life-stages are a key link between the benthic food web and mobile vertebrate predators. Our
study showed that bottom-up processes initiated by salmon subsidies and possibly light flux determined
key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some
of these interactions indirectly through its effects on the movement of organisms through the environment
Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment
An experiment and a mark-recapture field study of juvenile coho salmon (
Oncorhynchus
kisutch
) were conducted to identify controls of key energy flow chains in river food webs. In the small-scale
experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as
small wood and resource availability (tissue of adult Chinook salmon,
O. tshawytscha
) on nutrients, algae,
invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural
variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer
growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels
resulted in strong bottom-up effects on select invertebrates including increased population biomass of
chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We
link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.3
3
higher and coho consumption of these animals 3
3
higher in salmon-subsidized channels. PHS in
experimental channels was associated with reduced algal biomass, potentially in response to increased
invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was
negatively related to PHS and total fish density and positively related to Diptera drift biomass; however,
the effects of fish density and drift biomass on coho growth were relatively weak. The field study also
indicated that prey resource availability and coho growth were associated with differences in canopy cover,
with prey biomass and coho growth 2–4
3
higher in reaches receiving more sunlight. As in the experiment,
coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that
these taxa and life-stages are a key link between the benthic food web and mobile vertebrate predators. Our
study showed that bottom-up processes initiated by salmon subsidies and possibly light flux determined
key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some
of these interactions indirectly through its effects on the movement of organisms through the environment
Do fall additions of salmon carcasses benefit food webs in experimental streams?
This is the postprint version of the article. The printed version of the article can be found here: http://www.springerlink.com/content/jl0122219v283124/Research showing that salmon carcasses support the productivity and biodiversity of aquatic and riparian ecosystems has been conducted over a variety of spatial and temporal scales. In some studies, carcasses were manipulated in a single pulse or loading rate or manipulations occurred during summer and early fall, rather than simulating the natural dynamic of an extended spawning period, a gradient of loading rates, or testing carcass effects in late fall-early winter when some salmon stocks in the US Pacific Northwest spawn. To address these discrepancies, we manipulated salmon carcass biomass in 16 experimental channels located in the sunlit floodplain of the Cedar River, WA, USA between mid-September and mid-December, 2006. Total carcass loads ranged from 0–4.0 kg/m2 (0, 0.001, 0.01, 0.1, 0.5, 1.0, 2.0 and 4.0 kg/m2, n = 2 per treatment) and were added to mimic the temporal dynamic of an extended spawning period. We found little evidence that carcasses influenced primary producer biomass or fish growth; however, nutrients and some primary consumer populations increased with loading rate. These effects varied through time, however. We hypothesize that the variable effects of carcasses were a result of ambient abiotic condition, such as light, temperature and disturbance that constrained trophic response. There was some evidence to suggest peak responses for primary producers and consumers occurred at a loading rate of *1.0–2.0 kg/m2, which was similar to other experimental studies conducted during summer
Recipes for the derivation of water quality parameters using the high-spatial-resolution data from sensors on board Sentinel-2A, Sentinel-2B, Landsat-5, Landsat-7, Landsat-8, and Landsat-9 Satellites
Beyond cool: adapting upland streams for climate change using riparian woodlands
Managed adaptation could reduce the risks of climate change to the world's ecosystems, but there have been surprisingly few practical evaluations of the options available. For example, riparian woodland is advocated widely as shade to reduce warming in temperate streams, but few studies have considered collateral effects on species composition or ecosystem functions. Here, we use cross-sectional analyses at two scales (region and within streams) to investigate whether four types of riparian management, including those proposed to reduce potential climate change impacts, might also affect the composition, functional character, dynamics and energetic resourcing of macroinvertebrates in upland Welsh streams (UK). Riparian land use across the region had only small effects on invertebrate taxonomic composition, while stable isotope data showed how energetic resources assimilated by macroinvertebrates in all functional guilds were split roughly 50:50 between terrestrial and aquatic origins irrespective of riparian management. Nevertheless, streams draining the most extensive deciduous woodland had the greatest stocks of coarse particulate matter (CPOM) and greater numbers of ‘shredding’ detritivores. Stream-scale investigations showed that macroinvertebrate biomass in deciduous woodland streams was around twice that in moorland streams, and lowest of all in streams draining non-native conifers. The unexpected absence of contrasting terrestrial signals in the isotopic data implies that factors other than local land use affect the relative incorporation of allochthonous subsidies into riverine food webs. Nevertheless, our results reveal how planting deciduous riparian trees along temperate headwaters as an adaptation to climate change can modify macroinvertebrate function, increase biomass and potentially enhance resilience by increasing basal resources where cover is extensive (>60 m riparian width). We advocate greater urgency in efforts to understand the ecosystem consequences of climate change adaptation to guide future actions
- …