1,720,965 research outputs found
Figure 3 in Invertebrate communities, sediment parameters and food availability of intertidal soft-sediment ecosystems on the north coast of British Columbia, Canada
No full textFigure 3. Non-metric multidimensional scaling (nMDS) graphs showing infaunal invertebrate community at three intertidal mudflats on the north coast of British Columbia, Canada during the summer of 2017. (a) the infaunal community by mudflat and sampling round and (b) the vector overlay indicates the direction of increased density, with correlations>0.3 shown. CC: Cassiar Cannery. TB: Tyee Banks. WC: Wolfe Cove. Round A: 23 May–June 1. Round B: 21–26 June. Round C: 19–25 July. Round D: 18–24 August.Published as part of Campbell, Lily, Dudas, Sarah E., Juanes, Francis, Allen Gerwing, Alyssa M. & Gerwing, Travis G., 2020, Invertebrate communities, sediment parameters and food availability of intertidal soft-sediment ecosystems on the north coast of British Columbia, Canada, pp. 919-945 in Journal of Natural History 54 (15-16) on page 925, DOI: 10.1080/00222933.2020.1770886, http://zenodo.org/record/502082
Figure 3 in Potential impacts of logging on intertidal infaunal communities within the Kitimat River estuary
No full textFigure 3. Non-metric multidimensional scaling (nMDS) graphs of those abiotic sediment conditions measured at five locations per site (sediment particle size as well as organic matter and water content) at four intertidal mudflats in the Kitimat River Estuary, British Columbia, Canada, during the summer of 2017.Published as part of Gerwing, Travis G., Campbell, Lily, Allen Gerwing, Alyssa M., Allen, Shaun, Cox, Kieran, Rogers, Megan, Gray, Olivia, Drewes, Mitch & Juanes, Francis, 2019, Potential impacts of logging on intertidal infaunal communities within the Kitimat River estuary, pp. 2833-2855 in Journal of Natural History 52 (43-44) on page 2839, DOI: 10.1080/00222933.2018.1553249, http://zenodo.org/record/517807
Passive restoration and non-invasive monitoring of soft-sediment ecosystems on the North Coast of British Columbia, Canada
Get PDFSoft-sediment ecosystems can be degraded through anthropogenic development, leading to reduced habitat suitability for biological communities. On the North Coast of British Columbia, Canada, intensive industrial activity and coastal development has occurred, specifically around the Skeena and Kitimat River Estuaries. In addition to current development, both regions have the potential for further development, while also undergoing passive restoration from historical disturbances. Therefore, I aimed to broaden our understanding of passive restoration and non-invasive monitoring of intertidal soft-sediment ecosystems, by carrying out experiments at mudflats in both estuaries during the summer of 2017. Specifically, I aimed to expand the use of a non-invasive population assessment technique to novel species in soft-sediment ecosystems. Relationships between burrowing decapod abundance and burrow openings have been successfully used to estimate population sizes, but this technique has yet to be applied to large burrowing polychaetes, bivalves, or in regions of high macrofaunal diversity. As such, I assessed mudflats in regions of low (n = 1 species) and high (n = 8 species) biodiversity to determine if macrofauna abundances could be estimated from burrow openings on the sediment surface. Where only one burrowing bivalve species was present, a relationship between burrow openings and population abundance was not feasible, but burrow openings were useful in estimating total macrofaunal community abundance at a high diversity mudflat. This suggests that monitoring through burrow opening counts has the ability to detect overall changes in population abundance. Next, I examined the infaunal community, sediment conditions, and nutrient availability at one intertidal mudflat in the Skeena River Estuary following the cessation of heavy industrial activities (i.e. a salmon cannery and pulp mill) to determine the capacity for passive restoration. Sediment conditions varied spatiotemporally, and nutrient availability showed temporal variation but trends were difficult to relate to historical or current potential disturbances. The legacy of past development is still apparent on the infaunal community in the form of patchy distributions of disturbance-indicating taxa, but the mudflat appears to be in an overall healthy state with a diverse and functioning food web, indicating community recovery from historical activities. Results from these studies indicate passive restoration can be appropriate for estuarine soft-sediment ecosystems, while monitoring population abundance through burrow openings could be a method of detecting disturbances or tracking recovery of macrofaunal populations.Graduate2020-06-2
A freshwater invasive in a salty pond: Investigating the germination of invasive Yellow flag iris (Iris pseudacorus) in saline conditions and risk of invasion in coastal marine habitats
Get PDFNumerous generalities have been derived to explain how and why species become invasive. However, species may demonstrate niche shifts, differing phenotypic plasticity, or seemingly able to persist in novel conditions or interactions in disparate portions of their invaded range. As such, regionally tailored, species-specific understanding of invasive species ecology may be fundamental to deriving effective and efficient early detection monitoring and rapid-response control efforts.
Yellow flag iris (Iris pseudacorus L.) is a typically freshwater invasive aquatic plant that is sufficiently tolerant of saltwater to disperse through, establish in, and reach sexual and asexual maturity in coastal habitats characterized by full marine salinity (~33 practical salinity units [PSU]). Emerging research suggests that I. pseudacorus may display diverse responses to saline environments in different portions of its invaded range. As such, this thesis aims to clarify the germination response of I. pseudacorus seeds exposed to seawater and identify the risk of coastal invasion in southern British Columbia (BC, Canada) to inform where efficient early detection and rapid response management actions are best maximized.
The germination response of I. pseudacorus seeds exposed to saline conditions was evaluated. Seeds were collected from freshwater and coastal marine populations (two experimental source populations) and were immersed in fresh (0 PSU), brackish (13-15 PSU), or marine salinity (33-35 PSU) for 15, 30, 60, or 90 days before recovering in freshwater or remaining in saline conditions for the germination phase. The viability of ungerminated seeds and population-level seed traits (dried weight and testa thickness) were assessed. Gemination was fully inhibited by immersion in salinity unless seeds recovered in freshwater. The freshwater population of seeds consistently achieved higher germination than the coastal population, regardless of immersion salinity or duration. Remarkably high tissue viability among ungerminated seeds and population differences in mean seed coat thickness suggest that population germination differences may arise from dormancy mechanisms rather than seed fitness.
A Maxent species distribution model (SDM) was developed to explore the drivers of I. pseudacorus’s coastal habitat suitability and identify regions most at risk of invasion in southern BC to catalyze early detection monitoring and rapid response management efforts. Precipitation during the driest season (40.6% contribution to model prediction) and proximity to urban landscapes (24.9% contribution) were the strongest determinants of coastal habitat suitability. Habitats near perennial freshwater sources were found suitable, though proximity to these features was not essential (distance to freshwater 7% contribution). More generally, south-facing slopes (aspect 6.2% contribution) at or above the mean high tide extent (elevation 7.9% contribution) will likely facilitate the establishment of I. pseudacorus. Regional invasion hotspots are expected near Tofino and Ucluelet on Vancouver Island’s west coast, the southern Gulf Islands and southern Vancouver Island, and in the backshore of the Fraser River delta.
My research identifies the germination response of saline-exposed I. pseudacorus and key drivers and locations of coastal habitat suitability in southern British Columbia. These insights can inform the efficient execution of early detection and rapid response coastal monitoring and management strategies targeted at the emerging threat of coastal invasion by I. pseudacorus. While the invasion risk for the southern BC coast was derived, I. pseudacorus has a near-global invaded distribution. As such, understandings gleaned here can more broadly inform invasion dynamics of aquatic invasive plants and the invasive potential of other species with similar life history traits.Graduate2024-12-0
Reproductive ecology of the Sitka willow (Salix sitchensis ).
Get PDFSalix sitchensis, Sanson ex Bong, was shown to be ...pollinated by both wind and insect vectors in this study. Vector reliance and efficiency were variable by site as well as year, and pollen limitation was also observed. Asexual propagules had a higher survival rate and abundance compared to seedlings. Low seedling survival, an abundance of asexual propagules, and the presence of linkage disequilibrium suggested that asexual reproduction was occurring. However, all sampled individuals had a unique multilocus genotype and populations had a high level of genetic and genotypic diversity. These factors suggested that sexual reproduction is the dominant strategy in the observed populations of S. sitchensis. High gene flow and non-significant isolation by distance suggested that S. sitchensis exists as a large, continuous, interbreeding population along the sampled waterways in central British Columbia. Successful restoration of riparian habitat is dependent on species specific reproductive information and knowledge of how species interact with other riparian species. The data determined in this study may help future riparian restoration efforts, as the reproductive strategy of a common riparian willow and how it interacted with beavers (Castor canadensis Kuhl) was quantified.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b160050
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
