Spectral quantification of nonlinear behaviour of the nearshore seabed and correlations with potential forcings at Duck, N.C., U.S.A

Local bathymetric quasi-periodic patterns of oscillation are identified from monthly profile surveys taken at two shore-perpendicular transects at the USACE field research facility in Duck, North Carolina, USA, spanning 24.5 years and covering the swash and surf zones. The chosen transects are the two furthest (north and south) from the pier located at the study site. Research at Duck has traditionally focused on one or more of these transects as the effects of the pier are least at these locations. The patterns are identified using singular spectrum analysis (SSA). Possible correlations with potential forcing mechanisms are discussed by 1) doing an SSA with same parameter settings to independently identify the quasi-periodic cycles embedded within three potentially linked sequences: monthly wave heights (MWH), monthly mean water levels (MWL) and the large scale atmospheric index known as the North Atlantic Oscillation (NAO) and 2) comparing the patterns within MWH, MWL and NAO to the local bathymetric patterns. The results agree well with previous patterns identified using wavelets and confirm the highly nonstationary behaviour of beach levels at Duck; the discussion of potential correlations with hydrodynamic and atmospheric phenomena is a new contribution. The study is then extended to all measured bathymetric profiles, covering an area of 1100m (alongshore) by 440m (cross-shore), to 1) analyse linear correlations between the bathymetry and the potential forcings using multivariate empirical orthogonal functions (MEOF) and linear correlation analysis and 2) identify which collective quasi-periodic bathymetric patterns are correlated with those within MWH, MWL or NAO, based on a (nonlinear) multichannel singular spectrum analysis (MSSA). (...continued in submitted paper)Comment: 50 pages, 3 tables, 8 figure

Movements of Diadromous Fish in Large Unregulated Tropical Rivers Inferred from Geochemical Tracers

Patterns of migration and habitat use in diadromous fishes can be highly variable among individuals. Most investigations into diadromous movement patterns have been restricted to populations in regulated rivers, and little information exists for those in unregulated catchments. We quantified movements of migratory barramundi Lates calcarifer (Bloch) in two large unregulated rivers in northern Australia using both elemental (Sr/Ba) and isotope (87Sr/86Sr) ratios in aragonitic ear stones, or otoliths. Chemical life history profiles indicated significant individual variation in habitat use, particularly among chemically distinct freshwater habitats within a catchment. A global zoning algorithm was used to quantify distinct changes in chemical signatures across profiles. This algorithm identified between 2 and 6 distinct chemical habitats in individual profiles, indicating variable movement among habitats. Profiles of 87Sr/86Sr ratios were notably distinct among individuals, with highly radiogenic values recorded in some otoliths. This variation suggested that fish made full use of habitats across the entire catchment basin. Our results show that unrestricted movement among freshwater habitats is an important component of diadromous life histories for populations in unregulated systems

208Po populated through EC/β+decay

The structure of 208Po resulting from the EC/β + decay of 208At was studied at CERN’s ISOLDE Decay Station (IDS). The high statistics afforded by the high yield of 208At and the high efficiency HPGe clusters at the IDS allowed for greater insight into lower intensity transitions and thus significant expansion of the 208Po level scheme. Furthermore, investigation into the isomeric state yielded a new half life 377(9) ns in addition to uncovering new transitions populating the state.The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 654002. As well as the Science and Technology Facilities Council (UK) through grants ST/P005314/1, ST/L005743/1, ST/J000051/1, ST/L005670/1, and ST/P004598/1 and (PHR) by the UK Department of Business, Energy and Industrial Strategy (BEIS) via the National Measurement System. Further funding was provided by the German BMBF under contract 05P18PKCIA and ”Verbundprojekt 05P2018” as well as the Spanish MINECO grant FPA2015-65035-P.Peer reviewe

The formation of garnet in olivine-bearing metagabbros from the Adirondacks

A regional study of olivine-bearing metagabbros in the Adirondacks has permitted testing of the P(pressure)-T(temperature)-X(composition) dependence of garnet-forming reactions as well as providing additional regional metamorphic pressure data. Six phases, olivine, orthopyroxene, clinopyroxene, garnet, plagioclase and spinel, which can be related by the reactions: orthopyroxene+clinopyroxene+spinel +anorthite=garnet, and forsterite+anorthite=garnet occur together both in coronal and in equant textures indicative of equilibrium. Compositions of the respective minerals are typically Fo 25–72 , En 44–75 , En 30–44 Fs 9–23 Wo 47–49 , Pp 13–42 Alm 39–63 Gr 16–20 , An 29–49 and Sp 16–58 . When they occur in the same rock, equant and coronal garnets are homogeneous and compositionally identical suggesting that chemical equilibrium may have been attained despite coronal textures. Extrapolating reactions in the simple CMAS system to granulite temperatures and making thermodynamic corrections for solid solutions gives equilibration pressures (using the thermometry of Bohlen et al. 1980b) ranging from about 6.5 kb in the Lowlands and southern Adirondacks to 7.0–8.0 kb in the Highlands for the assemblage olivine-plagioclase-garnet. These results are consistent with inferred peak metamorphic conditions in the Adirondacks (Valley and Bohlen 1979; Bohlen and Boettcher 1981). Thus the isobaric retrograde path suggested by Whitney and McLelland (1973) and Whitney (1978) for the formation of coronal garnet in olivine metagabbros may not be required. Application of the same equilibria gives >8.7 kb for South Harris, Scotland and 0.9 kb for the Nain Complex. Disagreement of the latter value with orthopyroxeneolivine-quartz barometry (Bohlen and Boettcher 1981) suggests that the use of iron-rich rocks (olivines ≧Fa 50 ) results in errors in calculated pressures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47335/1/410_2004_Article_BF00371301.pd

Wave-forced dynamics in the nearshore river mouths, and swash zones

The role of wave forcing on the main hydro‐morphological dynamics evolving in the shallow waters of the nearshore and at river mouths is analyzed. Focus is mainly on the cross‐shore dynamics that evolve over mildly sloping barred, dissipative sandy beaches from the storm up to the yearly timescale, at most. Local and non‐local mechanisms as well as connections across three main inter‐related subsystems of the nearshore – the region of generation and evolution of nearshore bars, river mouths and the swash zone – are analyzed. The beach slope is a major controlling parameter for all nearshore dynamics. A local mechanism that must be properly described for a suitable representation of wave‐forced dynamics of all such three subsystems is the proper correlation between orbital velocity and sediment concentration in the bottom boundary layer; while specific dynamics are the wave–current interaction and bar generation at river mouths and the sediment presuspension at the swash zone. Fundamental non‐local mechanisms are both infragravity (IG) waves and large‐scale horizontal vortices (i.e. with vertical axes), both influencing the hydrodynamics, the sediment transport and the seabed morphology across the whole nearshore. Major connections across the three subsystems are the upriver propagation of IG waves generated by breaking sea waves and swash–swash interactions, the interplay between the swash zone and along‐river‐flank sediment transport and the evolution of nearshore sandbars

High turnover of fungal hyphae in incubation experiments

Soil biological studies are often conducted on sieved soils without the presence of plants. However, soil fungi build delicate mycelial networks, often symbiotically associated with plant roots (mycorrhizal fungi). We hypothesized that as a result of sieving and incubating without plants, the total fungal biomass decreases. To test this, we conducted three incubation experiments. We expected total and arbuscular mycorrhizal (AM) fungal biomass to be higher in less fertilized soils than in fertilized soils, and thus to decrease more during incubation. Indeed, we found that fungal biomass decreased rapidly in the less fertilized soils. A shift towards thicker hyphae occurred, and the fraction of septate hyphae increased. However, analyses of phospholipid fatty acids (PLFAs) and neutral lipid fatty acids could not clarify which fungal groups were decreasing. We propose that in our soils, there was a fraction of fungal biomass that was sensitive to fertilization and disturbance (sieving, followed by incubation without plants) with a very high turnover (possibly composed of fine hyphae of AM and saprotrophic fungi), and a fraction that was much less vulnerable with a low turnover (composed of saprotrophic fungi and runner hyphae of AMF). Furthermore, PLFAs might not be as sensitive in detecting changes in fungal biomass as previously thought