Living Shorelines Support Nearshore Benthic Communities in Upper and Lower Chesapeake Bay

Human population growth and sea-level rise are increasing the demand for protection of coastal property against shoreline erosion. Living shorelines are designed to provide shoreline protection and are constructed or reinforced using natural elements. While living shorelines are gaining popularity with homeowners, their ability to provide ecological services (e.g., habitat provision and trophic transfer) is not well understood, and information is needed to improve coastal and resource management decision-making. We examined benthic community responses to living shorelines in two case-study subestuaries of Chesapeake Bay using a before-after control-impact study design. At Windy Hill, a bulkhead was removed and replaced by three tombolos, sand fill, and native marsh vegetation. At Lynnhaven, 25 m of eroding marsh shoreline was stabilized with coir logs, sand fill, and native marsh vegetation. Communities of large (>?3 mm) infauna adjacent to living shorelines at both locations tended to increase in biomass by the end of the study period. Community compositions changed significantly following living shoreline construction at Windy Hill, reflecting a trend toward higher density and biomass of large bivalves at living shorelines compared to pre-construction. Increasing trends in density and biomass of clams and simultaneously decreasing density and decreasing trends in biomass of polychaetes suggest a transition toward stable infaunal communities at living shorelines over time, though longer-term studies are warranted.     

Mineral ballast and particle settling rates in the coastal upwelling system off NW Africa and the South Atlantic

The ocean off NW Africa is the second most important coastal upwelling system with a total annual primary production of 0.33 Gt of carbon per year (Carr in Deep Sea Res II 49:59–80, 2002). Deep ocean organic carbon fluxes measured by sediment traps are also fairly high despite low biogenic opal fluxes. Due to a low supply of dissolved silicate from subsurface waters, the ocean off NW Africa is characterized by predominantly carbonate-secreting primary producers, i.e. coccolithophorids. These algae which are key primary producers since millions of years are found in organic- and chlorophyll-rich zooplankton fecal pellets, which sink rapidly through the water column within a few days. Particle flux studies in the Mauretanian upwelling area (Cape Blanc) confirm the hypothesis of Armstrong et al. (Deep Sea Res II 49:219–236, 2002) who proposed that ballast availability, e.g. of carbonate particles, is essential to predict deep ocean organic carbon fluxes. The role of dust as ballast mineral for organic carbon, however, must be also taken into consideration in the coastal settings off NW Africa. There, high settling rates of larger particles approach 400 m day⁻¹, which may be due to a particular composition of mineral ballast. An assessment of particle settling rates from opal-production systems in the Southern Ocean of the Atlantic Sector, in contrast, provides lower values, consistent with the assumptions of Francois et al. (Global Biogeochem Cycles 16(4):1087, 2002). Satellite chlorophyll distributions, particle distributions and fluxes in the water column off NW Africa as well as modelling studies suggest a significant lateral flux component and export of particles from coastal shelf waters into the open ocean. These transport processes have implications for paleo-reconstructions from sediment cores retrieved at continental margin settings.     

Barnacle distribution in Lough Hyne Marine Nature Reserve: a new baseline and an account of invasion by the introduced Australasian species Elminius modestus Darwin

The distribution and abundances of the following species of barnacles were established in autumn 2001 within the Lough Hyne Marine Nature Reserve: Cthamalus stellatus, Cthamalus montagui, Semibalanus balanoides, Elminius modestus, Balanus crenatus and Verruca stroemia. The results of the survey showed a clear distinction between the vertical distribution and the abundance of barnacle species inside Lough Hyne, and those sites sampled in the Rapids and outside the Lough. The Lough is now dominated by the introduced Australasian species E. modestus. This species was first recorded outside Lough Hyne in 1956. By 1988 it was found occasionally throughout the Lough, and appreciable numbers were recorded in 1990–1991. It has now replaced all other species in some parts of the North Basin. At sites subject to freshwater influence it is totally dominant, including in the highly sheltered Goleen site where intertidal barnacles have not previously been recorded. It is suggested that, once established in the North Basin, the sheltered nature of the Lough, combined with high summer temperatures and limited circulation, fostered retention of larvae and heavy spatfall of E. modestus.     

Application of geochemical mapping techniques to a complex Precambrian shield area in Labrador, Canada

Lake sediment and water geochemical data from a complex area of the Canadian shield in Labrador, Canada, display spatial variation patterns that can be linked to bedrock geology. Composite variables derived by R-mode factor analysis are effective in discriminating large-scale lithotectonic divisions, but single-element raw or residual data (corrected for effects of lake depth, Fe, Mn and LOI) provide better resolution of smaller-scale features and major tectonic boundaries.Archean high-grade gneiss regions are typified by high pH and Ni, coupled with depletion of U and F. This signature is developed most strongly over mafic igneous rocks, but is present also over Archean granitoid orthogneisses. Archean crust affected by Proterozoic structural and thermal reworking retains a high Ni signature, but is not depleted in U and F. An Early Proterozoic belt of felsic intrusive and extrusive rocks is defined by enrichment in F, U, Mo, Pb and Zn. Single-element variations suggest large-scale zonation of the belt, with the strongest enrichment over blocks interpreted to represent high crustal levels. Prominent geochemical boundaries coincide with major faults within this belt. High-grade metamorphic terranes comprising Early to Middle Proterozoic crust affected by the 1.0-Ga Grenville Orogeny show low geochemical relief, and are characterized by strong depletion in incompatible elements.In addition to reflecting the dominant rock types in each domain, some of these patterns may be related to the age, erosion level and orogenic history of the crust. For example, the Archean signature may reflect fundamental contrasts in the compositions of Archean and Proterozoic crust, suggested also by lithogeochemical and petrogenetic studies. Geochemical zonation over Early Proterozoic igneous rocks may be a function of crustal level, with the most differentiated granites, volcanic rocks and hydrothermal mineralization present in the uppermost levels of the belt. Depletion of incompatible elements over both Archean and Proterozoic high-grade metamorphic rocks may reflect expulsion of these elements by dehydration and anatexis.     

The effects of salinity on the Manila clam (Ruditapes philippinarum) using the neutral red retention assay with adapted physiological saline solutions

This study investigated the internal osmotic regulatory capabilities of the Manila clam (Ruditapes philippinarum) following in vivo exposure to a range of salinities. A second objective was to measure the health status of the Manila clam following exposure to different salinities using the neutral red retention (NRR) assay, and to compare results using a range of physiological saline solutions (PSS). On exposure to seawater of differing salinities, the Manila clam followed a pattern of an osmoconformer, although they seemed to partially regulate their circulatory haemolytic fluids to be hyperosmotic to the surrounding aqueous environment. Significant differences were found when different PSS were used, emphasizing the importance of using a suitable PSS to reduce additional osmotic stress. Using PSS in the NRR assay that do not exert additional damage to lysosomal membrane integrity will help to more accurately quantify the effects of exposure to pollutants on the organism(s) under investigation.     

Challenges and solutions of remote sensing at offshore wind energy developments

Radar is becoming an important tool used to gather data on bird and bat activity at proposed and existing land-based wind energy sites. Radar will likely play an even more important role at the increasing development of wind energy offshore, given both the lack of knowledge about bird and bat activity offshore and the increased difficultly in obtaining offshore information. Most radar studies to date have used off-the-shelf or modified marine radars. However, there are several issues that continue to hinder the potential usefulness of radar at wind energy sites, with offshore sites providing a particular suite of challenges. We identify these challenges along with current or developing solutions.     

Speleoseismology: A critical perspective

Speleoseismology is the investigation of earthquake records in caves. Traces can be seen in broken speleothems, growth anomalies in speleothems, cave sediment deformation structures, displacements along fractures and bedding plane slip, incasion (rock fall) and co-seismic fault displacements. Where earthquake origins can be proven, these traces constitute important archives of local and even regional earthquake activity. However, other processes that can generate the same or very similar deformation features have to be excluded before cave damage can be interpreted as earthquake induced. Most sensitive and therefore most valuable for the tracing of strong earthquake shocks in caves are long and slender speleothems, such as soda straws, and deposits of well-bedded, water-saturated silty sand infillings, particularly in caves close to the earth's surface. Less easily proven is a co-seismic origin of an incasion and other forms of cave damage. The loads and creep movements of sediment and ice fillings in caves can cause severe damage to speleothems which have been frequently misinterpreted as evidence of earthquakes. For the dating of events in geological archives, it is important to demonstrate that such events happened at approximately the same time, i.e. within the error bars of the dating methods. A robust earthquake explanation for cave damage can only be achieved by the adoption of appropriate methods of direct dating of deformation events in cave archives combined with correlation of events in other geological archives outside caves, such as the deformation of lake and flood-plain deposits, locations of rock falls and active fault displacements.     

An approach to the mapping of the statistical properties of gradient winds (over Canada)

This paper describes the preparation of a preliminary set of maps of gradient‐level wind climate over Canada and some neighbouring regions of the United States. The data for this study were drawn from twice‐daily records of radiosonde ascents at a network of ten Canadian upper air stations. The period covered by the data was 1960–69, and this was supplemented by statistical information on upper level winds at fourteen points in the United States.

The analysis and subsequent mapping were carried out for 300 and 500 m above ground level and were based on a number of statistical models: the bivariate Gaussian distribution of wind velocities characterized by the vector mean and standard vector deviation, monthly Weibull distributions of wind speed and a new model of extreme annual wind occurrences developed from a consideration of wind as a stochastic process.