Frontshear and backshear instabilities of the mean longshore current

An analytical model based on Bowen and Holman [1989] is used to prove the existence of instabilities due to the presence of a second extremum of the background vorticity at the front side of the longshore current. The growth rate of the so-called frontshear waves depends primarily upon the frontshear but also upon the backshear and the maximum and the width of the current. Depending on the values of these parameters, either the frontshear or the backshear instabilities may dominate. Both types of waves have a cross-shore extension of the order of the width of the current, but the frontshear modes are localized closer to the coast than are the backshear modes. Moreover, under certain conditions both unstable waves have similar growth rates with close wave numbers and angular frequencies, leading to the possibility of having modulated shear waves in the alongshore direction. Numerical analysis performed on realistic current profiles confirm the behavior anticipated by the analytical model. The theory has been applied to a current profile fitted to data measured during the 1980 Nearshore Sediment Transport Studies experiment at Leadbetter Beach that has an extremum of background vorticity at the front side of the current. In this case and in agreement with field observations, the model predicts instability, whereas the theory based only on backshear instability fai led to do so.

Generation and nonlinear evolution of shore-oblique/transverse sand bars

The coupling between topography, waves and currents in the surf zone may selforganize to produce the formation of shore-transverse or shore-oblique sand bars on an otherwise alongshore uniform beach. In the absence of shore-parallel bars, this has been shown by previous studies of linear stability analysis, but is now extended to the finite-amplitude regime. To this end, a nonlinear model coupling wave transformation and breaking, a shallow-water equations solver, sediment transport and bed updating is developed. The sediment flux consists of a stirring factor multiplied by the depthaveraged current plus a downslope correction. It is found that the cross-shore profile of the ratio of stirring factor to water depth together with the wave incidence angle primarily determine the shape and the type of bars, either transverse or oblique to the shore. In the latter case, they can open an acute angle against the current (upcurrent oriented) or with the current (down-current oriented). At the initial stages of development, both the intensity of the instability which is responsible for the formation of the bars and the damping due to downslope transport grow at a similar rate with bar amplitude, the former being somewhat stronger. As bars keep on growing, their finite-amplitude shape either enhances downslope transport or weakens the instability mechanism so that an equilibrium between both opposing tendencies occurs, leading to a final saturated amplitude. The overall shape of the saturated bars in plan view is similar to that of the small-amplitude ones. However, the final spacings may be up to a factor of 2 larger and final celerities can also be about a factor of 2 smaller or larger. In the case of alongshore migrating bars, the asymmetry of the longshore sections, the lee being steeper than the stoss, is well reproduced. Complex dynamics with merging and splitting of individual bars sometimes occur. Finally, in the case of shore-normal incidence the rip currents in the troughs between the bars are jet-like while the onshore return flow is wider and weaker as is observed in nature.

Influence on present-day coastal dynamics and evolution of a relict subaqueous delta lobe: Sol de Riu lobe, Ebro Delta. Continental Shelf Research, 74: 94-104. doi:10.1016/j.csr.2013.11.021

We used high-resolution swath-bathymetry data to characterise the morphology of the abandoned subaqueous Sol de Riu delta lobe in the Ebro Delta, Western Mediterranean Sea. This study aims to assess the influence of an abandoned delta lobe on present-day coastal dynamics in a micro-tidal environment. Detailed mapping of the relict Sol de Riu lobe also showed a set of bedforms interpreted as footprints of human activities: seasonal V-shaped depressions on the middle shoreface due to boat anchoring and old trawling marks between 16 and 18 m water depth. Estimations of the mobility of bottom sediment showed that the shallowest shoreface (i.e. less than 7 m depth) is the most dynamic part of the relict lobe, while the middle shoreface experienced significant morphological changes since the lobe was abandoned. The deepest shoreface (i.e. water depth in excess of 15 m), which corresponds to the front of the lobe, is defined by a very small potential for morphological change. Simulations showed that while the relict lobe does not significantly affect the typical short period waves (Tp ≈4 s) in the study area, it does interfere with the most energetic wave conditions (Tp ≥ 7 s) acting as a shoal leading to the concentration of wave energy along the shoreline northwest of the lobe. The consequence of such modification of the high-energy wave propagation pattern by the relict lobe is an alteration of the wave-induced littoral sediment dynamics with respect to a situation without the lobe.

1214-008 Clear Lake Watershed Final Report

Clear Lake, Iowa's third largest natural lake, is a premier natural resource and popular recreational destination in north central Iowa. Despite the lake's already strong recreational use, water quality concerns have not allowed the lake to reach its full potential. Clear Lake is listed on Iowa's Draft 2010 303(d) Impaired Waters List for algae, bacteria, and turbidity. Many restoration practices have been implemented to treat the algae and turbidity impairment, but few practices have been installed to treat bacteria. Reducing beach bacteria levels is a priority of the lake restoration partners. Federal, State, and local partners have invested more than $20 million in lake and watershed restoration efforts to improve water clarity and quality. These partners have a strong desire to ensure high bacteria levels at public swim beaches do not undermine the other water quality improvements. Recent bacteria source tracking completed by the State Hygienic Laboratory indicates that Canada Geese are a major contributor of bacteria loading to the Clear Lake swim beaches. Other potential sources include unpermitted septic systems in the watershed. The grant request proposes to reduce bacteria levels at Clear Lake's three public swim beaches by utilizing beach cleaner machines to remove goose waste, installing goose deterrents at the swim beaches, and continuing a septic system update grant program. These practices began to be implemented in 2011 and recent bacteria samples in 2012 are showing they can be effective if the effort is continued.

Descripció geoambiental i paisatgística del sistema platja-duna de cala Borró (cap Ras, Alt Empordà- Costa Brava, Girona)

The geoambiental and landscape description of the beach-dune system of Cala Borró, (Cap Ras), placed in the town of Colera (Alt Empordà), is carried out. The dunar system, developed with orientation and N-S, links three beach pockets following the topographic slopes of the torrential basins. We find coalescence of dunes in the upper zones, which were possibly an object of reafforestation in the 19thC. to avoid erosion

Deu anys de seguiment demogràfic i genètic d’Stachys maritima a Catalunya (2001-2010). Implicacions per a un pla de recuperació

Ten years of demographic and genetic monitoring of Stachys maritima in Catalonia (2001-2010). Implications for a recovery plan.- Stachys maritima is a species typical of the coastal dunes, with a wide distribution within the Mediterranean Basin. In spite of this, the species shows a clear regression. In Catalonia, it has been observed an important reduction of its populations since early 20th century, where it has disappeared from several localities in which it was relatively common (Tarragonès, Barcelonès). Herein we present the results of the demographic monitoring of the species during the last 10 years (2001-2010) in the known localities in Catalonia. Besides corroborating the disappearance (northern Sant Martí d’Empúries), the re-discovering (Llobregat Delta beach) and the detection of new populations (inner dunes of the Montgrí), a large year-to-year fluctuation of the monitored populations is stated; the possible reasons are discussed. In addition, the present work also includes the results of the allozyme diversity analysis of the new detected populations as well as the rediscoveries of the period 2004-2008, which were not included in a former study of genetic diversity carried out in 2002-2003. It is necessary to emphasize that the contribution of the new populations to the genetic diversity of Stachys maritima is very small, which can be attributed to their limited population size and /or to founder effects. Despite that the species is included in the Annex 2 (“En Perill d’Extinció”) within the Catàleg de Flora Amenaçada de Catalunya (Catalogue of Endangered Flora of Catalonia), and some “soft” conservation measures have been applied at local level (signposting of the beach accesses, environmental education, etc.) coupled with other more significant measures (e.g. translocation of individuals discovered in an artificial sandbank), it would be necessary the coordinated action and the scientific support of any initiative of conservation that could be carried out. The general frame to initiate actions of conservation should be the recovery plan of Stachys maritima, whose draft and application is mandatory in accordance to the Catàleg

Impacto de las proliferaciones de medusas en la valoración económica ambiental de las playas de Denia (Sudoeste Mediterráneo), Alicante, España

El actual incremento de medusas en las costas mediterráneas, percibido como un factor negativo en la calidad de las playas, supone un factor reductor de la demanda turística en las ubicaciones costeras, sobre todo en aquellas más afectadas por éstas proliferaciones. Debido a que la época de mayor presencia de fitoplacton disponible (principal fuente de alimento de las medusas), relacionada a la alta incidencia lumínica, coincide con la temporada alta de turismo en el verano; las notificaciones de incidencias por picaduras de medusa en esta época son frecuentes. Ejemplo de ello, es el caso de Denia (Alicante, España) donde, desde 2008, se ha detectado un considerable aumento de incidencias sanitarias a causa de picaduras de medusa, paralela a la aparición de la especie invasora de cubomedusa Carybdea marsupialis (Bordehore et al, 2011). En este estudio se ha realizado una valoración económica de la playa como un bien ambiental recreativo, mediante encuestas semi-estructuradas elaboradas por Paulo Nunes (CIESM), aplicadas a una muestra inicial de 300 individuos; y evaluado cual sería el impacto social y económico en la valoración ambiental de Denia, si las proliferaciones de medusa no se estabilizaran. Se ha estimado el valor económico del impacto sicial causado por las bioinvasiones marinas en las playas recreacionistas según Nunes and Van den Bergh (2004) y Nunes and Markandya (2008); el método que también ha sido aplicado en el mismo estudio aplicado en Israel (B. Galil, J. Gowdy and P. Nunes 2012) y en Cataluña (2013, Paulo Nunes, M. Loureiro, L. Piñol, S. Sastre, L. Voltaire). En ambos casos los resultados en el impacto económico son considerables pero menores a los esperados, al igual que en los resultados obtenidos en Denia (Alicante).

The effect on prices of the attributes of holiday hotels: a hedonic prices approach

This article examines the effect on price of different characteristics of holiday hotels in the sun-and-beach segment. The effect on price is estimated under the hedonic function perspective by means of random effect models, known also as mixed or panel models. Some 82,000 prices were gathered between 1991 and 1998 from tour operator catalogues. The study reveals huge price differences between 4-star hotels and the rest, coupled with practically no difference between 1-star and 2-star hotels. Other attributes with a significant effect on price are town, hotel size, distance to the beach and availability of parking place. The results can assist hotel managers in shaping pricing and investment strategies

Reencontro de Balanoglossus gigas Fr. Muller no litoral brasileiro

Re-finding of Balanoglossus gigas FR. MUULLER on the brasilian sea shore. Balanoglossus gigas, the giant Enteropneusta, has been described for the first time by Fritz Muller in his notes collected and published by Dr. HERMANN VON IHERING (1898, pg. 35). FR. MULLER found the Balanoglossus on the coats of the State of Santa Catarina in 1884. Once again in 1885 several specimens of that animal were captured by FR. MULLER in the same place. Since that time up to now no references on the occurrence of this animal have been found in the zoological bibliography. During the spring of 1948 Prof. W. BESNARD, Director of he Instituto Paulista de Oceanografia saw some signals indicating the existence of Balanoglossus at the beach of São Sebastião, State of São Paulo. From 1948 to now several attempts have been made to catch the animal alive and complete. On the last September during a shorts visit to the beach of São Sebastião one Balanoglossus was captured and brought to the Department of General and Animal Physiology in good conditions. The animal measured 1.80 m in length. It seems to be the largest Balanoglossus known. According to the descriptions of SPENGEL (1893, pg. 158), and VAN DER HORST (1939) pg. 717) it was possible to identify this Enteropneusta as Balanoglossus gigas FR. MULLER, refound at the Brazilian coast sixty six years after its discovery by FR. MÜLLER.

Reformaation historian kertauskurssi lautapelinä

Peliarvostelu

Population ecology of Paepalanthus polyanthus (Bong.) Kunth: demography and life history of a sand dune monocarpic plant

Aspects of population dynamics and life history of Paepalanthus polyanthus (Bong.) Kunth, a sand dune monocarpic plant, were evaluated. A five year study was carried out on three permanent plots (5 m x 5 m) in a sand dune slack at Joaquina beach, Santa Catarina State, Brazil. From December 1986 to June 1989, the population decreased due to the death of the post reproductive plants and a low emergence of seedlings. In June 1989, a great recruitment occurred, but no plants survived. The population re-established itself by 1990-1991. The emergence and high survival of seedlings depended on periods of high pluviosity. Nevertheless, the summer flooding and episodes of drought represented key factors in mortality. The birth and mortality rates varied among the areas. It is suggested that these differences are related with depth of the ground water and with vegetation cover at each site. Paepalanthus polyanthus can reproduce in the second year of life, but few plants do this. The chances of survival and reproduction increase with the size of the basal leaf rosette. Although the production of seeds increases with size, the risk of unexpected flooding, for instance, suggest that a great delay in reproduction might not be the most favorable strategy.

Spatial variation in the structure and floristic composition of "restinga" vegetation in southeastern Brazil

We examined large-scale spatial variation of structural parameters and floristic composition in open Clusia scrub, a vegetation type of the Brazilian "restingas" (sandy coastal plain vegetation). This vegetation is organized in islands separated by sandy stretches with sparse herbaceous vegetation. We located 12 sample areas on three consecutive beach ridges, lying parallel to the coastline and at different distances from the ocean, in close proximity to two lagoons (Cabiúnas and Comprida). Each sample area was divided into three strips. We used the line intercept method to sample all woody plants ³ 50 cm tall. We used nested ANOVA to verify structural variation between different sampling scales. TWINSPAN analysis was performed to examine the variation in floristic composition between areas. The overall diversity index was 3.07. Six species are repeatedly dominant throughout the entire sampling area. There was homogeneity in relation to diversity and species richness between beach ridges but not within beach ridges. Floristic composition and structural parameters did not vary in relation to distance from the sea but floristic composition did vary as a function of proximity to Cabiúnas or Comprida lagoon. Differences in plant cover between sample areas may be related to the paleoformation of this sandy coastal plain.

The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of São Paulo, Brazil

The range of 25-hydroxyvitamin D (25OHD) concentration was determined in a young healthy population based on bone metabolism parameters and environmental and behavioral aspects. We studied 121 healthy young volunteers (49 men, 72 women) living in São Paulo (23º 34' south latitude) belonging to three occupational categories: indoor workers (N = 28), medical school students (N = 44), and resident physicians (N = 49). Fasting morning blood samples were collected once from each volunteer from August 2002 to February 2004, and 25OHD, total calcium, albumin, alkaline phosphatase, phosphorus, creatinine, intact parathyroid hormone, osteocalcin, and type I collagen carboxyterminal telopeptide were measured. Data are reported as means ± SD. Mean subject age was 24.7 ± 2.68 years and mean 25OHD level for the entire group was 78.7 ± 33.1 nM. 25OHD levels were lower (P < 0.05) among resident physicians (67.1 ± 27.0 nM) than among students (81.5 ± 35.8 nM) and workers (94.0 ± 32.6 nM), with the last two categories displaying no difference. Parathyroid hormone was higher (P < 0.05) and osteocalcin was lower (P < 0.05) among resident physicians compared to non-physicians. Solar exposure and frequency of beach outings showed a positive association with 25OHD (P < 0.001), and summer samples presented higher results than winter ones (97.8 ± 33.5 and 62.9 ± 23.5 nM, respectively). To define normal levels, parameters such as occupational activity, seasonality and habits related to solar exposure should be taken into account. Based on these data, we considered concentrations above 74.5 nM to be desired optimal 25OHD levels, which were obtained during the summer for 75% of the non-physicians.

Dynamic ecosystems under anthropogenic stress : how does macrotidal sandy fauna respond to green tides?

Highly dynamic systems, often considered as resilient systems, are characterised by abiotic and biotic processes under continuous and strong changes in space and time. Because of this variability, the detection of overlapping anthropogenic stress is challenging. Coastal areas harbour dynamic ecosystems in the form of open sandy beaches, which cover the vast majority of the world’s ice-free coastline. These ecosystems are currently threatened by increasing human-induced pressure, among which mass-development of opportunistic macroalgae (mainly composed of Chlorophyta, so called green tides), resulting from the eutrophication of coastal waters. The ecological impact of opportunistic macroalgal blooms (green tides, and blooms formed by other opportunistic taxa), has long been evaluated within sheltered and non-tidal ecosystems. Little is known, however, on how more dynamic ecosystems, such as open macrotidal sandy beaches, respond to such stress. This thesis assesses the effects of anthropogenic stress on the structure and the functioning of highly dynamic ecosystems using sandy beaches impacted by green tides as a study case. The thesis is based on four field studies, which analyse natural sandy sediment benthic community dynamics over several temporal (from month to multi-year) and spatial (from local to regional) scales. In this thesis, I report long-lasting responses of sandy beach benthic invertebrate communities to green tides, across thousands of kilometres and over seven years; and highlight more pronounced responses of zoobenthos living in exposed sandy beaches compared to semi-exposed sands. Within exposed sandy sediments, and across a vertical scale (from inshore to nearshore sandy habitats), I also demonstrate that the effects of the presence of algal mats on intertidal benthic invertebrate communities is more pronounced than that on subtidal benthic invertebrate assemblages, but also than on flatfish communities. Focussing on small-scale variations in the most affected faunal group (i.e. benthic invertebrates living at low shore), this thesis reveals a decrease in overall beta-diversity along a eutrophication-gradient manifested in the form of green tides, as well as the increasing importance of biological variables in explaining ecological variability of sandy beach macrobenthic assemblages along the same gradient. To illustrate the processes associated with the structural shifts observed where green tides occurred, I investigated the effects of high biomasses of opportunistic macroalgae (Ulva spp.) on the trophic structure and functioning of sandy beaches. This work reveals a progressive simplification of sandy beach food web structure and a modification of energy pathways over time, through direct and indirect effects of Ulva mats on several trophic levels. Through this thesis I demonstrate that highly dynamic systems respond differently (e.g. shift in δ13C, not in δ15N) and more subtly (e.g. no mass-mortality in benthos was found) to anthropogenic stress compared to what has been previously shown within more sheltered and non-tidal systems. Obtaining these results would not have been possible without the approach used through this work; I thus present a framework coupling field investigations with analytical approaches to describe shifts in highly variable ecosystems under human-induced stress.