The Gulf Stream Front, Its Role in Larval Fish Survival and Recruitment in Florida: Hydrographic Station and Plankton Data

The goal of this project was to develop a clearer understanding of the role that the Gulf Stream system plays in larval fish survival and recruitment in Florida waters. The specific objectives of this study were to: Determine whether the biomass of fish larva, other zooplankton, microzooplankton and phytoplankton is higher at the shoreward front of the Gulf Stream than on either side of it. Characterize the assemblages of fish larvae predators and prey both at the front and on either side of it. Determine if the composition, abundance and size frequency distribution of larval and juvenile fishes in the front is different from that in the coastal zone or in the Gulf Stream. Monitor the position of the Gulf Stream by continuous measurements of physical variables at moorings located in the Gulf Stream off Fort Lauderdale and within Port Everglades. This project was a first effort to characterize the coupling between physical and biological processes that may influence the early life histories of fishes in Florida\u27s coastal waters. This report contains the hydrographic and plankton data from the project. It is intended to facilitate data access by the scientific and management communities. Interpretations and detailed analyses of these data are being given in meeting presentations, peer-reviewed journal articles (Stone et al. draft manuscript, Braker et al. draft manuscript, Frazel et al. in preparation) and graduate theses (Stone 1993; Braker 1993)

Seaweed fertilisation impacts the chemical and isotopic composition of barley : Implications for analyses of archaeological skeletal remains

This research was partially funded by the European Social Fund and Scottish Funding Council as part of Developing Scotland's Workforce in the Scotland 2014–2020 European Structural and Investment Fund Programme. The contribution of staff from the University of the Highlands and Islands' Agronomy Institute and the James Hutton Institute to the field trial was supported by Rural and Environment Science and Analytical Services (RESAS) funding from the Scottish Government. GPS geolocation was performed by archaeologists of the Orkney Research Centre for Archaeology (ORCA). Stable isotope ratio measurements were performed at the Scottish Universities Environmental Research Centre (SUERC), East Kilbride, and elemental composition analysis was performed at the Trace Element Speciation Laboratory, Aberdeen (TESLA). MB would like to thank IM's family for their help collecting and storing the decomposing seaweed.Peer reviewedPostprintPostprin

Owning the land, but at what cost? Changes in power relations and land accumulation in cattle ranching in wartime Colombia

Given the length of the conflict and multiplicity of actors embedded in the Colombian war, it becomes necessary to understand the impact that violence, displacement and dispossession have amongst rural producers and in the agroeconomic sector in general. The struggle for land tenure, the management of natural resources, and the economic and social centrality of cattle ranching for various armed actors, are therefore vital aspects to consider in understanding the effects of the conflict in rural Colombia. Important contributions have been made, shedding light on the nature of war in Colombia and its negative societal effects, as well as a vast theoretical corpus has been established on the importance of livestock, not only for producing families, but also for rural elites and other active agents of armed confrontation. However, in addition to the already known effects, both of war (such as dispossession, displacement, loss of social order, poverty, etc.), and the role of livestock in it (as a means of financing confrontation, among others), the information available in Colombia suggests that other important and unexpected changes take place in land tenure, especially for women farmers. This research thus delves into the transformations in the ownership of the agricultural production units (UPA) dedicated to livestock production during the escalation of conflict in Colombia (2001-2012), to understand the relationship between war and societal dynamics of land tenure through a quantitative approach. Available data indicates that dynamics such as displacement, increasing violence rates and territorial instability contribute, at least to a certain extent, to transforming family dynamics and patterns in land tenure and administration. This is relevant not only for understanding the complexity of women's roles and functions within livestock farming, and for the analysis of their contingent agency in war contexts, but also contributes to a larger narrative on the unexpected outcomes of a longstanding war. Here we revisit the narratives about the role and participation of women in conflict and in livestock farming, while also exploring the circumstances in which gender roles, family relations and land ownership can shift

Applying co-integrated panel models to estimate long-term relationships between cattle production and greenhouse gas emissions for Latin America

The cattle sector is key to the economy of several Latin American countries, however, it strongly contributes to environmental degradation through the emission of greenhouse gases and deforestation, among others. The objective of this study is to analyze the long- and short-term relationships of variables such as population growth, expansion of pastureland, and deforestation with cattle greenhouse gas emissions and beef and dairy production for 15 Latin American countries. Using information consolidated by FAOSTAT for the period between 1990-2019, a cointegrated panel method (Pooled Median Group) was applied, with which six specifications were estimated. The main results show that, in the long-term, a population growth of 1% decreases methane emissions derived from manure management in beef production by 1.41% and increases those derived from enteric fermentation by 0.97%. Likewise, a 1% expansion of pastureland increases methane emissions from manure management by 2.66% and decreases those related to enteric fermentation by 2.15%. The results indicate that at the aggregate level for the region there is evidence of stable long-term relations. This means that the effects population growth, the expansion of pastureland, and deforestation have on greenhouse gas emissions from cattle production tend to decrease over time. This long-term behavior may be marked by those countries that have a more developed cattle sector, aimed at reducing the impacts of cattle production on the environment, for example, by supporting the adoption of improved forage technologies, silvo-pastoral systems, grazing management practices, and regulatory frameworks and incentives. The cattle sector of these countries can be used as a regional benchmark and its lessons learned as inputs for sustainable intensification processes in countries with a developing cattle sector

The Determinants of Activity and Specificity in Actinorhodin Type II Polyketide Ketoreductase

SummaryIn the actinorhodin type II polyketide synthase, the first polyketide modification is a regiospecific C9-carbonyl reduction, catalyzed by the ketoreductase (actKR). Our previous studies identified the actKR 94-PGG-96 motif as a determinant of stereospecificity. The molecular basis for reduction regiospecificity is, however, not well understood. In this study, we examined the activities of 20 actKR mutants through a combination of kinetic studies, PKS reconstitution, and structural analyses. Residues have been identified that are necessary for substrate interaction, and these observations have suggested a structural model for this reaction. Polyketides dock at the KR surface and are steered into the enzyme pocket where C7–C12 cyclization is mediated by the KR before C9-ketoreduction can occur. These molecular features can potentially serve as engineering targets for the biosynthesis of novel, reduced polyketides

Vertical profiles of light absorption and scattering associated with black carbon particle fractions in the springtime Arctic above 79◦ N

Despite the potential importance of black carbon (BC) for radiative forcing of the Arctic atmosphere, ver- tically resolved measurements of the particle light scatter- ing coefficient (σsp ) and light absorption coefficient (σap ) in the springtime Arctic atmosphere are infrequent, espe- cially measurements at latitudes at or above 80◦ N. Here, re- lationships among vertically distributed aerosol optical prop- erties (σap, σsp and single scattering albedo or SSA), par- ticle microphysics and particle chemistry are examined for a region of the Canadian archipelago between 79.9 and 83.4◦ N from near the surface to 500 hPa. Airborne data collected during April 2015 are combined with ground- based observations from the observatory at Alert, Nunavut and simulations from the Goddard Earth Observing Sys- tem (GEOS) model, GEOS-Chem, coupled with the TwO- Moment Aerosol Sectional (TOMAS) model (collectively GEOS-Chem–TOMAS; Kodros et al., 2018) to further our knowledge of the effects of BC on light absorption in the Arctic troposphere. The results are constrained for σsp less than 15 Mm−1, which represent 98 % of the observed σsp, be- cause the single scattering albedo (SSA) has a tendency to be lower at lower σsp, resulting in a larger relative contribution to Arctic warming. At 18.4 m2 g−1, the average BC mass ab- sorption coefficient (MAC) from the combined airborne and Alert observations is substantially higher than the two aver- aged modelled MAC values (13.6 and 9.1 m2 g−1) for two different internal mixing assumptions, the latter of which is based on previous observations. The higher observed MAC value may be explained by an underestimation of BC, the presence of small amounts of dust and/or possible differences in BC microphysics and morphologies between the obser- vations and model. In comparing the observations and simulations, we present σap and SSA, as measured, and σap/2 and the corresponding SSA to encompass the lower modelled MAC that is more consistent with accepted MAC values. Me- dian values of the measured σap, rBC and the organic com- ponent of particles all increase by a factor of 1.8 ± 0.1, going from near-surface to 750 hPa, and values higher than the sur- face persist to 600 hPa. Modelled BC, organics and σap agree with the near-surface measurements but do not reproduce the higher values observed between 900 and 600 hPa. The dif- ferences between modelled and observed optical properties follow the same trend as the differences between the mod- elled and observed concentrations of the carbonaceous com- ponents (black and organic). Model-observation discrepan- cies may be mostly due to the modelled ejection of biomass burning particles only into the boundary layer at the sources. For the assumption of the observed MAC value, the SSA range between 0.88 and 0.94, which is significantly lower than other recent estimates for the Arctic, in part reflecting the constraint of σsp < 15 Mm−1. The large uncertainties in measuring optical properties and BC, and the large differ- ences between measured and modelled values here and in the literature, argue for improved measurements of BC and light absorption by BC and more vertical profiles of aerosol chemistry, microphysics and other optical properties in the Arctic