Schist

Silent walk through Vancouver Island in the middle of winter.

Managing alternative stable states in constructed wetlands using artificial substrates

Algal blooms are a management concern in shallow water bodies. This project investigated the use of artificial substrates to enhance biofilm growth and shift primary production from the open water to artificial surfaces. This resulted in a shift from algal dominated wetland back to a clear water macrophyte dominated wetland.

Asymmetric impact of piscivorous birds on size-structured fish populations

Fish are frequently considered the top predator in freshwater food web models despite evidence that predatory birds can impact fish populations. In this study, we quantified bird predation rates on experimental populations of rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) created by stocking nine small lakes in British Columbia, Canada. Combining estimates of fish mortality with estimated bird predation rates allowed us to partition fish mortality into that due to birds versus cannibalism. Our results indicated that bird predators had significant impacts on age-1 trout populations, but little impact on age-0 trout. Common loons (Gavia immer Brunnich, 1764) were the principle predator among eight predatory bird species present, apparently consuming nearly 50% of all stocked age-1 trout and explaining almost 50% of variation in mortality rates. Age-1 trout mortality did not differ significantly from zero in lakes without loons. Birds consumed a small proportion of age-0 trout, and estimated consumption explained none of the variation in age-0 trout mortality among lakes. We conclude that birds affect fish populations by asymmetric predation on different age (size) classes and can be important top predators that should not be ignored when characterizing freshwater food webs in lakes.

Rigs-to-reefs: Will the deep sea benefit from artificial habitat?

As a peak in the global number of offshore oil rigs requiring decommissioning approaches, there is growing pressure for the implementation of a "rigs-to-reefs" program in the deep sea, whereby obsolete rigs are converted into artificial reefs. Such decommissioned rigs could enhance biological productivity, improve ecological connectivity, and facilitate conservation/restoration of deep-sea benthos (eg cold-water corals) by restricting access to fishing trawlers. Preliminary evidence indicates that decommissioned rigs in shallower waters can also help rebuild declining fish stocks. Conversely, potential negative impacts include physical damage to existing benthic habitats within the "drop zone", undesired changes in marine food webs, facilitation of the spread of invasive species, and release of contaminants as rigs corrode. We discuss key areas for future research and suggest alternatives to offset or minimize negative impacts. Overall, a rigs-to-reefs program may be a valid option for deep-sea benthic conservation. © The Ecological Society of America.

Asynchrony and regional differences in the reproductive cycle of the greenback stingaree Urolophus viridis from south-eastern Australia

Determining the periodicity of the reproductive cycle in chondrichthyan species when the population is recruiting asynchronously, as found for Urolopus viridis, can be problematic. The reproductive cycle generally requires distinguishable trends in reproductive indices across the population. The present study utilised other similar and sympatric urolophid species with synchronous reproductive cycles. Through data collected in the present study and comparisons of maximum total length (TL), periodicity of egg and embryo in utero, ovarian cycles, largest ovarian follicle diameter, and matrotrophic contribution (percentage increase from egg to embryo after maternal histotroph supplement) from similar studies, an annual reproductive cycle can be hypothesised. Sampling across two separate regions of Lakes Entrance (LE) and Western Bass Strait (WBS), U. viridis also showed regionality in several of the reproductive indices. Maximum TL and mass for females, mean size-at-birth, and female size-at-maturity and size-at-maternity in LE were markedly smaller than in WBS. In both regions litter size (1–2) increased with TL, with an exception of one female in WBS producing a litter of 3 which could be attributed to the larger TL. The implication of U. viridis producing such few young annually is they have the lowest biological productivity of any urolophid species in south-eastern Australia.

Use of geographical information system and remote sensing techniques for planning culture-based fisheries in non-perennial reservoirs of Sri Lanka

 The presence of a wide areal extent of small-sized village reservoirs offers a considerable potential for the development of culture-based fisheries (CBFs) in Sri Lanka. To this end, this study uses geographical information systems (GISs) and remote sensing (RS) techniques to determine the morphometric and biological characteristics most useful for classifying non-perennial reservoirs for CBF development and for assessing the influence of catchment land-use patterns on potential CBF yields. The reservoir shorelines at full water supply level were mapped with a Global Positioning System to determine shoreline length and reservoir areal extent. The ratio of shoreline length to reservoir extent, which was reported to be a powerful predictor variable of CBF yields, could be reliably quantified using RS techniques. The areal extent of reservoirs, quantified with RS techniques (RS extent), was used to estimate the ratio of forest cover plus scrubland cover to RS extent and was found to be significantly related to the CBF yield (R2 = 0.400; P < 0.05). The results of this study indicated that morphometric characteristics and catchment land-use patterns, which might be viewed as indices of biological productivity, can be quantified using RS and GIS techniques. © 2014 Wiley Publishing Asia Pty Ltd.

Time-in-area represents foraging activity in a wide-ranging pelagic forager

Successful Marine Spatial Planning depends upon the identification of areas with high importance for particular species, ecosystems or processes. For seabirds, advancements in biologging devices have enabled us to identify these areas through the detailed study of at-sea behaviour. However, in many cases, only positional data are available and the presence of local biological productivity and hence seabird foraging behaviour is inferred from these data alone, under the untested assumption that foraging activity is more likely to occur in areas where seabirds spend more time. We fitted GPS devices and accelerometers to northern gannets Morus bassanus and categorised the behaviour of individuals outside the breeding colony as plunge diving, surface foraging, floating and flying. We then used the locations of foraging events to test the efficiency of 2 approaches: time-in-area and kernel density (KD) analyses, which are widely employed to detect highly-used areas and interpret foraging behaviour from positional data. For KD analyses, the smoothing parameter (h) was calculated using the ad hoc method (KDad hoc), and KDh=9.1, where h = 9.1 km, to designate core foraging areas from location data. A high proportion of foraging events occurred in core foraging areas designated using KDad hoc, KDh=9.1, and time-in-area. Our findings demonstrate that foraging activity occurs in areas where seabirds spend more time, and that both KD analysis and the time-in-area approach are equally efficient methods for this type of analysis. However, the time-in-area approach is advantageous in its simplicity, and in its ability to provide the shapes commonly used in planning. Therefore, the time-in-area approach can be used as a simple way of using seabirds to identify ecologically important locations from both tracking and survey data.

The development of a conceptual model and self-reported measure of occupational health and safety vulnerability

Injuries at work have a substantial economic and societal burden. Often groups of labour market participants, such as young workers, recent immigrants or temporary workers are labelled as being "vulnerable" to work injury. However, defining groups in this way does little to enable a better understanding of the broader factors that place workers at increased risk of injury. In this paper we describe the development of a new measure of occupational health and safety (OH&S) vulnerability. The purpose of this measure was to allow the identification of workers at increased risk of injury, and to enable the monitoring and surveillance of OH&S vulnerability in the labour market. The development included a systematic literature search, and conducting focus groups with a variety of stakeholder groups, to generate a pool of potential items, followed by a series of steps to reduce these items to a more manageable pool. The final measure is 29-item instrument that captures information on four related, but distinct dimensions, thought to be associated with increased risk of injury. These dimensions are: hazard exposure; occupational health and safety policies and procedures; OH&S awareness; and empowerment to participate in injury prevention. In a large sample of employees in Ontario and British Columbia the final measure displayed minimal missing responses, reasonably good distributions across response categories, and strong factorial validity. This new measure of OH&S vulnerability can identify workers who are at risk of injury and provide information on the dimensions of work that may increase this risk. This measurement could be undertaken at one point in time to compare vulnerability across groups, or be undertaken at multiple time points to examine changes in dimensions of OH&S vulnerability, for example, in response to a primary prevention intervention.

Hierarchical analysis of avian re-nesting behavior: mean, across-individual, and intra-individual responses

© 2015, Springer-Verlag Berlin Heidelberg. Anti-predator behavior is a key aspect of life history evolution, usually studied at the population (mean), or across-individual levels. However individuals can also differ in their intra-individual (residual) variation, but to our knowledge, this has only been studied once before in free-living animals. Here we studied the distances moved and changes in nest height and concealment between successive nesting attempts of marked pairs of grey fantails (Rhipidura albiscapa) in relation to nest fate, across the breeding season. We predicted that females (gender that decides where the nest is placed) should on average show adaptive behavioral responses to the experience of prior predation risk such that after an unsuccessful nesting attempt, replacement nests should be further away, higher from the ground, and more concealed compared with replacement nests after successful nesting attempts. We found that, on average, females moved greater distances to re-nest after unsuccessful nesting attempts (abandoned or depredated) in contrast to after a successful attempt, suggesting that re-nesting decisions are sensitive to risk. We found no consistent across-individual differences in distances moved, heights, or concealment. However, females differed by 53-fold (or more) in their intra-individual variability (i.e., predictability) with respect to distances moved and changes in nest height between nesting attempts, indicating that either some systematic variation went unexplained and/or females have inherently different predictability. Ignoring these individual differences in residual variance in our models obscured the effect of nest fate on re-nesting decisions that were evident at the mean level.

Interferência da Brachiaria Decumbens Stapf. sobre plantas daninhas em sistema de consórcio com o milho

Forage plants cultivated in consortium with crop corn, facilitating the weed control in farming and cattle raising ecosystem, interfering not only in your biological productivity, like in your potential of distribution and infestation in area. This experiment was realized with the aim to evaluate the weed suppress by Brachiaria decumbens in intercropping with corn (Zea mays L.). The even was composed by combination of four forage plant density (0, 10, 15 and 20 kg ha(-1)) and three weed species (Ipomoea grandifolia, Digitaria horizontalis and Cenchrus echinatus), planted intercropping with corn. It was constated that B. decumbens was efficient in weed infestation suppress, being the most effective control for D. horizontalis. The leaf area and dry phytomass of weeds were affected (P<0.05) by forage plant presence, with variation between the density curve of Brachiaria only for weed D. horizontalis and I. grandifolia.

Partitioning the relative fitness effects of diet and trophic morphology in the threespine stickleback

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento de cafeeiros (Coffea arabica L. cv. mundo novo) oriundos de ecossistemas diversos, sob condições uniformes

Estudou-se o desempenho de cafeeiros (Coffea arabica L. cv. Mundo Novo) originários de quatro ecossistemas diferentes (sombra, meia sombra, pleno sol e casa de vegetação), quando submetidos a condições de campo. Realizaram-se avaliações da morfologia, desenvolvimento e produtividade biológica do cafeeiro. Efetuaram-se também determinações da nutrição mineral, infestação de pragas e solarização. O crescimento em altura revelou-se superior nas plantas originárias de casa de vegetação e meia sombra. O número de ramos mostrou-se mais elevado em cafeeiros provenientes de locais mais ensolarados, sendo que plantas originárias de locais mais sombreados apresentaram maior número de folhas por ramo. Nestes três parâmetros notou-se uma tendência de recuperação nas condições de campo em cafeeiros provenientes de sombra. O peso da matéria seca foliar revelou-se mais elevado em plantas oriundas de meia sombra e mais baixo naquelas provenientes de casa de vegetação, sendo que nos dois ocorreu adaptação às condições de campo num período de 75 dias. O peso da matéria seca do caule e das raízes mostrou-se mais alto nos cafeeiros originários de casa de vegetação, sendo que a melhor adaptação às condições uniformes também ocorreu com as plantas oriundas da sombra. Quanto ao aspecto nutricional, determinaram-se teores mais elevados de N foliar em plantas oriundas de pleno sol e níveis mais altos de P e Ca em cafeeiros originários de meia sombra. Esse tratamento promoveu também acúmulo de Zn no cafeeiro. O caule dos cafeeiros mostrou teores de nutrientes inferiores às folhas, exceto o nível mais alto de Zn e os níveis semelhantes de Cu. Plantas originárias de pleno sol apresentaram teores mais elevados de Ca e S. As raízes mostraram níveis de nutrientes superiores ao caule e inferiores às folhas, exceto no caso do Cu, Zn e Mn, que se revelaram mais altos no sistema radicular. O nível de infestação de Perileucoptera coffeclla mostrou-se mais elevado nas plantas provenientes de casa de vegetação, sendo que cafeeiros originários de locais sombreados revelaram-se pouco afetados. A infestação de Coccus viridis revelou-se sempre mais elevada em plantas provenientes de meia sombra. Cafeeiros oriundos de pleno sol e ca sa de vegetação não sofreram solarização, sendo que aqueles provenientes de meia sombra e sombra sofreram danos crescentes nas folhas. Sombreamento afetou o desenvolvimento dos cafeeiros em função de sua intensidade e interação com outros fatores bióticos e abióticos do ecossistema.

Specific depth cone resistivity measurements to determine soil engineering properties

The University of British Columbia (UBC) began performing piezocone penetration tests (CPTU) with electrical resistivity measurements (RCPTU) in 1989. Since then, RCPTU research at UBC has focused on obtaining geo-environmental parameters such as fluid resistivity and soil engineering properties such as porosity and degree of saturation from measurements of bulk soil electrical resistivity using the empirical relationship proposed by Archie (1942). Within this framework, the paper illustrates and discusses important design and calibration issues for resistivity modules such as the use of isolated circuitry to achieve linear calibrations over large ranges of resistivity. The suitability of RCPTU measurements for determination of geo-environmental and geotechnical parameters are assessed using typical ranges of soil and groundwater properties and methods of isolating individual factors for study are discussed. Illustrative examples of RCPTU research efforts including the environmental characterization of mine tailings, delineation of saline water intrusions in fresh water aquifers and the quality control of geotechnical ground densification are presented throughout the text. It is shown that groundwater temperature and hence ion mobility is not significantly altered by frictional heat generated during piezocone penetration and that ratio-based approaches to monitoring soil porosity can be used to eliminate the requirement for extensive groundwater sampling programs. Lastly, it is shown that RCPTU measurements above the water table can only be made using resistivity modules that are stable over a large range of resistivities and that such measurements are the most difficult to interpret because of grain surface conduction effects and generally unknown fluid resistivities.

Dinâmica da comunidade microfitoplanctônica relacionada com os parâmetros físico-químicos do estuário do rio Guajará-Mirim (Vigia - PA)

Estuários são ambientes ricos em nutrientes, favorecendo a reprodução e desenvolvimento de diversas espécies. Nestes, o fitoplâncton representa uma considerável parcela da produção primária e, em conjunto com outros fatores, regula os níveis de produtividade biológica. Este estudo teve o objetivo de conhecer a dinâmica do microfitoplâncton e sua correlação com os fatores ambientais no estuário do rio Guajará-mirim, na cidade de Vigia- PA, que é um importante pólo pesqueiro do estado do Pará. Foram realizadas coletas bimestrais de fitoplâncton e parâmetros físico-químicos em quatro estações de coleta ao longo do estuário, durante os períodos de maré vazante e enchente. Foram determinadas a composição específica e densidade do microfitoplâncton (org.L-1) e realizadas análises de frequência de ocorrência, diversidade e equitabilidade, agrupamento e componentes principais (ACP). Sazonalmente, nota-se, principalmente durante a maré vazante, uma considerável variação dos parâmetros físico-químicos que está fortemente relacionada ao ciclo hidrológico da região. Foram registrados 78 táxons pertencentes às Divisões Bacillariophyta (65), Chlorophyta (6), Cyanophyta (3), Dinophyta (3), e Ochrophyta (1). A divisão Bacillariophyta foi predominante em numero de espécies, frequência de ocorrência e densidade (99,89%). A densidade média mensal do microfitoplâncton variou de 9.999 (julho) a 535.411 org. L-1 (janeiro). Durante o mês de janeiro ocorreu uma floração de Skeletonema costatum (máx = 1.996.613 org. L-1). A comunidade microfitoplanctônica caracterizou-se como de diversidade média (média geral anual = 2,40). A variação sazonal dos parâmetros físico-químicos e da densidade das espécies foi o fator preponderante no agrupamento de amostras, tendo se formado dois grandes grupos, o primeiro composto por amostras do período chuvoso e o segundo grupo composto por amostras do período de estiagem. A análise de componentes principais mostrou que, apesar de os parâmetros físico-químicos apresentarem baixa variabilidade espacial e sazonal, a variação do índice de pluviosidade, do teor de sólidos totais dissolvidos e da salinidade foi determinante na variação da densidade de grande parte das espécies e também favoreceu um leve aumento da diversidade no período de estiagem.