18 research outputs found
Summary Data for Cross-Shore Transects (Winter 2016-Summer 2020) - Humboldt Coastal Resiliency Project and Climate Ready Project
Sea level rise and/or extreme events are capable of causing excessive erosion on the beaches and foredunes that line the outer edges of the barriers enclosing Humboldt Bay and the Eel River delta within the Eureka littoral cell. Erosion of these protective barriers threatens the natural and cultural resources and infrastructure behind them in two significant estuaries. A major goal of the Climate Ready Project and the Humboldt Coastal Resilience Project was to quantify present day beach-dune morphodynamics, which could then be used to model the impacts of sea level rise and extreme events. For this purpose, a total of 73 cross-shore transects were established along the littoral cell. Elevation and vegetation data collected on transects will be used in a quantitative model to predict beach, dune and barrier responses to sea level rise and extreme events. The purpose of this report is to present raw data in the form of graphs of elevation change along transects as the basis of qualitative observations of response during the period of data collection, 2016-2020. The primary audience is property owners within the study site. Conclusions of this report are based on qualitative analysis and may change when modeling is complete
Dynamic restoration and the impact of native versus invasive vegetation on coastal foredune morphodynamics, Lanphere Dunes, California, USA
The Lanphere Dunes, part of the Humboldt Bay National Wildlife Refuge, has been the focus of foredune restoration efforts since the 1980s. Efforts have centred around removal of an invasive European beach grass species, Ammophila arenaria, introduced in the early 1900s to stabilize the dunes to protect landward communities from coastal flooding and storm surges. Despite effectively stabilizing the foredune, A. arenaria forms monotypic vegetation stands, with highly dense roots, rhizomes, and above-ground biomass that can lead to pronounced scarping of the seaward slope, alongshore steering of wind and sediment, a lack of landward transfer of sand, and a steeper, more peaked profile.
Effective foredune restoration must consider the coupled interactions between dominant plant type and the geomorphic processes that influence dune form. A 5 ha reach of recently restored foredune was monitored biannually with terrestrial laser scanner and uncrewed aerial systems platforms between 2015 and 2021 to characterize the impacts of dynamic restoration on foredune form and resiliency. This reach included two control plots: (1) native, non-restored and (2) invasive, and three restored plots revegetated with native species: (3) a native grass (Elymus mollis), (4) a low-lying herb and subshrub assemblage, and (5) a mixture of the native grass, herbs, and subshrubs.
After five growing seasons, restored plots exhibited distinct geomorphic and sediment budget differences. Natively vegetated plots recovered from extensive scarping 2 years faster than the invasive plot. Restored plots saw foredune height (0.5–0.7 m) and width increase, landward extension (1 m) while maintaining a similar seaward position, and positive lee-slope sediment budgets that exceeded both control plots. These results suggest that the native vegetation plots allowed increased landward sand transport across the foredune, and increased the capacity of the foredune to recover more quickly following dune scarping
Seed bank persistence of a South American cordgrass in invaded northern Atlantic and Pacific Coast estuaries
Invasive alien plant species impart considerable impacts that contribute to the decline of biodiversity worldwide. The ability of an invasive species to overcome barriers to establish and spread in new environments, and the long-term effects of plant invasions supporting their persistence are keys to invasion success. The capacity of introduced species to form soil seed banks can contribute to their invasiveness, yet few studies of invaders have addressed seed bank dynamics. Improved knowledge of this recruitment process can improve conservation management. We studied temporal and spatial changes in soil seed bank characteristics of the cordgrass Spartina densiflora from two continental invaded ranges. In the Odiel Marshes (Southwest Iberian Peninsula), S. densiflora formed transient seed banks (<1 year). At Humboldt Bay Estuary (California), viable seeds persisted for at least 4 years though the germination percentage fell abruptly after the first year from 29 % to less than 5 % of remaining viable seeds. Total soil seed bank density increased with S. densiflora above-ground cover in both estuaries, pointing to the transient component of the seed bank as a critical component of vegetation dynamics during S. densiflora invasion. Even so, seed densities as high as c. 750 seeds m-2 in Odiel Marshes and c. 12 400 seeds m-2 in Humboldt Bay were recorded in some plots without fruiting S. densiflora plants. S. densiflora spikelet (dispersal unit) density was more than double close to the sediment surface than deeper within soil. Our study shows the importance of evaluating seed banks during the design of invasive species management since seed bank persistence may vary among invaded sites, and can affect the timing and duration required for desired management outcomes
Foredune morphodynamics and sediment budgets at seasonal to decadal scales: Humboldt Bay National Wildlife Refuge, California, USA.
© 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license:
http://creativecommons.org/licenses/by-nc-nd/4.0/
This author accepted manuscript is made available following 24 month embargo from date of publication (June 2018) in accordance with the publisher’s archiving policyCoastal foredunes are shore-parallel ridges that form in the backshore and their morphodynamics are controlled partly by seasonal and spatial variations in the coastal (onshore) sediment budget that, in turn, are driven by oceanic and atmospheric processes and interactions, including regional wave and wind regimes, climatic variability events (e.g., ENSO), sediment availability, beach characteristics (e.g., width, slope), and vegetation type and cover in the backshore. Previous studies on shoreline change in Northern California report only broad rates of erosion and accretion related to regional meteorological regimes. This study presents a more detailed, multi-decadal to seasonal account of shoreline response and foredune morphodynamics along a 2.5 km stretch of coast in the Humboldt Bay National Wildlife Refuge (HBNWR). Analysis of historical aerial photography (1939–2014) reveals trends in shoreline position that are coupled with more detailed assessments of foredune morphodynamics and seasonal scale volumetric changes from cross-shore topographic profiles``. These findings set the historical context of foredune morphodynamics and allow exploration of the implications of seasonal meteorological variation on long-term (75-year) foredune evolution and development at the HBNWR.
DSAS describes maximum foredune progradation in the north (up to +0.51 m a−1) and maximum foredune retreat in the south (up to −0.49 m a−1). Aerial photograph analysis (2004–2014) shows statistically significant larger erosive features in the southern zone than in the northern and central zones. Seasonal volume calculations from cross-shore profiles indicate statistically significant differences in alongshore transect elevation and foredune volume, with larger elevations and volumes in the northern and central zones than in the southern. Combined with evidence of seasonal bidirectional littoral drift, these data support a north to south gradient in sediment availability, foredune position and resulting stages of established foredune development. Seasonal storm energies and climate forcing events introduce variability in erosive patterns but support the persistence of alongshore developmental stages. Future research should explore foredune morphodynamics on a smaller spatial scale and changes related to the presence/absence of multiple vegetation assemblages
Supporting Spartina: Interdisciplinary perspective shows Spartina as a distinct solid genus
In 2014 a DNA-based phylogenetic study confirming the paraphyly of the grass subtribe Sporobolinae proposed the creation of a large monophyletic genus Sporobolus, including (among others) species previously included in the genera Spartina, Calamovilfa, and Sporobolus. Spartina species have contributed substantially (and continue contributing) to our knowledge in multiple disciplines, including ecology, evolutionary biology, molecular biology, biogeography, experimental ecology, environmental management, restoration ecology, history, economics, and sociology. There is no rationale so compelling to subsume the name Spartina as a subgenus that could rival the striking, global iconic history and use of the name Spartina for over 200 years. We do not agree with the arguments underlying the proposal to change Spartina to Sporobolus. We understand the importance of taxonomy and of formalized nomenclature and hope that by opening this debate we will encourage positive feedback that will strengthen taxonomic decisions with an interdisciplinary perspective. We consider the strongly distinct, monophyletic clade Spartina should simply and efficiently be treated as the genus Spartina
Habilidades funcionais, nível de actividade, integração na comunidade e saúde em idosos institucionalizados em lar: resultados preliminares
São escassos os estudos portugueses que avaliam o nível de funcionalidade, o nível de actividade e a saúde em idosos institucionalizados em lar.
Objectivos: Estimar os meses de institucionalização dos idosos e as causas que conduziram à institucionalização em lar, bem como o número de idosos que partilha o seu quarto com outros. Estimar as Habilidades Funcionais dos idosos, o tipo de actividades relatadas, dentro e fora da instituição (Nível de Actividade e Integração na Comunidade) e o grau de saúde (objectiva e subjectiva). Analisar a relação entre estas quatro dimensões e analisar a relação destas com algumas variáveis demográficas (idade, género).
Métodos: 35 idosos institucionalizados em lar (idade média=80.20 anos; DP=6.263) completaram o Questionário de Informação Pessoal (QIP; Fernándes-Ballesteros, 1995; Maia et al., 2013). Para a análise dos dados recorremos ao SPSS 21.
Resultados: A grande generalidade dos idosos está institucionalizada há mais de 16 meses, por motivos maioritariamente de saúde (65,7%), partilha o quarto com terceiros (71.4%) e é autónoma, não necessitando de ajuda (56.7%) em actividades como o cuidado pessoal, comer, vestir/despir, andar, levantar/deitar. Quando se trata das actividades mais complexas, como a administração de dinheiro, uso do telefone ou ida às compras, o grau de dependência aumenta (27.6% dos sujeitos necessitam de muita ajuda e 35.2% de alguma ajuda). Verifica-se que 72.9% da população está inactiva, visto limitar-se a ver televisão ou a ouvir rádio e apenas 14.3% dos idosos se dedicam a actividades fora da Instituição. Os actos religiosos têm uma larga adesão (88.6%). 79.4% dos idosos reporta problemas de mobilidade e 35.3% problemas de foro psicológico. Verifica-se que 45.7% percepcionam a saúde como má, com as mulheres a percepcionarem a sua saúde mais negativamente do que os homens. Nenhum dos idosos, de ambos os géneros, percepciona a sua saúde como boa ou excelente (0%). A dimensão Nível de Actividade apresenta uma correlação positiva com a dimensão Integração na Comunidade (r=.448*). O género apresenta uma correlação significativa com a dimensão Habilidades Funcionais (rho=.383*) e com a dimensão Saúde (r=.414*). O estado civil apresentou uma correlação positiva com as Habilidades Funcionais (rho=.419*) e o grau de escolaridade apresentou uma correlação negativa e com a dimensão Saúde (r=-.446*).
Conclusões: Na nossa amostra a institucionalização é causada maioritariamente devido a problemas de saúde. A maioria dos idosos partilha o seu quarto o que pode afectar a sua intimidade e bem-estar. Apesar da maioria dos idosos ser funcionalmente autónoma, a grande generalidade apresenta uma vida pautada pela inactividade e por fracos laços com o exterior. As mulheres percepcionam a sua saúde mais negativamente do que os homens. Importa assim, desenvolver estratégias que conduzam a um envelhecimento activo destes idosos
<i>Ammophila</i> Invasion Ecology and Dune Restoration on the West Coast of North America
The invasive ecosystem engineer Ammophila arenaria, native to Europe, was first introduced to California (USA) in 1896. More than a century later, it has come to dominate coastal foredune vegetation on the west coast of North America to the near exclusion of native species. A. arenaria builds a narrow, steep, peaked, and densely vegetated foredune, in contrast to the broad, more sparsely vegetated foredunes built by the native Elymus mollis. As such, it has modified dune processes by fixing the foredune and disrupting exchange of sediment between the beach, foredune, and dunefield. In the 1930s the congener A. breviligulata, native to the east coast and Great Lakes USA, was first introduced to Oregon, and has been displacing A. arenaria in southern Washington. Ammophila spp. have drastically reduced biodiversity, outcompeting native plant species, and displacing both invertebrate and vertebrate species. Restoration of west coast dunes through the removal of Ammophila began in the 1990s. Methods usually consist of one or a combination of manual digging, burning/herbicides, or excavation with heavy equipment. There are benefits and disadvantages to each method. Manual removal has proven most effective at restoring foredune form and process but is expensive. Excavation and herbicides may result in the loss of foredune morphology. Managers must articulate goals carefully before selecting restoration methods
Variation in Tussock Architecture of the Invasive Cordgrass Spartina Densiflora along the Pacific Coast of North America
Some introduced species spread rapidly beyond their native range and into novel habitats mediated by a high degree of phenotypic plasticity and/or rapid evolutionary responses. In this context, clonality has been described as a significant factor contributing to invasiveness. We studied the abiotic environment and the responses of different tussock architecture traits of the invasive cordgrass Spartina densiflora Brongn. (Poaceae). A common garden experiment and field studies of S. densiflora in salt marshes across a wide latitudinal gradient from California (USA) to British Columbia (Canada) provided a model system for an integrated study of the potential mechanisms underlying the response of invasive S. densiflora populations to changes in environmental conditions. Our results showed that S. densiflora is able to adjust to widely variable climate (specifically, air temperature and the duration of the growing season) and sediment conditions (specifically, texture and hypoxia) through phenotypical plastic key functional tussock traits (e.g. shoot density, height, above- and below-ground biomass allocation patterns). Root biomass increased in coarser sediments in contrast to rhizomes, which were more abundant in finer sediments. Above-ground biomass and leaf area index increased mainly with air temperature during summer, and more robust (taller and wider) shoots were associated with more oxygenated sediments. In view of our results, S. densifloraappears to be a halophyte with a high degree of phenotypic plasticity that would enable it to respond successfully to changes in the abiotic conditions of salt marshes driven by global climate change, such as increasing salinity and temperatures
The HECT Domain of the Ubiquitin Ligase Rsp5 Contributes to Substrate Recognition*
Ubiquitin modification of endosomal membrane proteins is a signal for active inclusion into the Multivesicular Body (MVB) pathway, resulting in lysosomal degradation. However, the endosome represents a dynamic site of protein sorting with a majority of proteins destined for recycling, rather than MVB targeting. Substrate recognition by ubiquitin ligases is therefore highly regulated. We have investigated substrate recognition by the Nedd4 ortholog Rsp5 as a model for understanding ligase-substrate interactions. Rsp5 interacts directly with its substrate Cps1 via a novel interaction mode. Perturbation of this mode of interaction revealed a compensatory role for the Rsp5 adaptor Bsd2. These results highlight the ability of Rsp5 to interact with substrates via multiple modalities, suggesting additional mechanisms of regulating this interaction and relevant outcomes