Effects of artificial openings of intermittently opening estuaries on macroinvertebrate assemblages of the entrance barrier

Intermittently opening estuaries are artificially opened to manage flood risk, water quality, recreational amenity, and fisheries; however, the ecological impacts of this management technique are incompletely understood. During 2001 and 2004, this study assessed the impacts of artificial openings on the macroinvertebrates of entrance barriers of intermittently opening estuaries in New South Wales (Australia). In 2001 macroinvertebrates were sampled once before artificial opening and 9 and 25 d after re-formation of the entrance barrier. A multiple before–after-control-impact analysis found that, although entrance barriers were destroyed by the artificial openings and then re-formed naturally by wave action, significant interactions for taxonomic richness, density of the amphipod Paracalliope australis (Gammaridae) and density of the gastropod mollusc Aschoris victoriae (Hydrobiidae) meant that the effects of this disturbance could not be distinguished from the natural variations that occurred in unopened estuaries. Multivariate analyses found that assemblages at both opened and unopened estuaries changed from before to after the openings, and the magnitude of the dissimilarity between times varied between estuaries. In 2004, macroinvertebrates were sampled on three randomly selected days within each of three periods (before, 3 d and 42 d after) at one opened and three unopened estuaries. Asymmetrical analysis of this modified before–after-control-impact study found that the change in taxonomic richness at the opened estuary from before to after opening did not differ from temporal changes that occurred in unopened estuaries. Short-term variation (i.e. between days) in total density of macroinvertebrates and density of P. australis in the re-formed entrance barrier of the opened estuary also did not differ from the variation in the control estuaries. Additionally, assemblage structure was not significantly changed by the opening and assemblages at two control estuaries were also unchanged over the same time. Individual taxa and assemblages of macroinvertebrates in entrance barriers of these intermittently open estuarine systems appear to be resilient to the habitat disturbance caused by artificial openings.     

Carbon neutral policy in action: the case of Bhutan

Climate policy across the world is proceeding at a highly variable pace, with some places very committed to decarbonizing their economies and others just beginning. Emerging nations are generally just starting along this journey. However, among the few nation states that have pledged to achieve carbon neutrality, is Bhutan, a least developed country. Carbon neutrality is an ambitious climate policy that is increasingly being recognized as necessary in order to stabilize global temperature rise at 1.5°C. However, Bhutan is likely to face significant challenges in maintaining this status as the country balances its desire to grow in economic opportunities (GDP) and in human happiness (GNH). Little research has been conducted inside the policy processes to better understand how Bhutan will maintain carbon neutrality. Through open-ended, semi-structured interviews with key stakeholders, this study provides an inside view on the current situation and future challenges that Bhutan may face, along with the complexities associated with implementing and maintaining an ambitious carbon neutral policy. The paper highlights Bhutan's story and how it could be useful for policy learning and knowledge sharing, especially in the context of emerging nations’ climate governance.     

Experimentalist governance in climate finance: the case of REDD+ in Brazil

One of the most significant impacts of the United Nations Framework Convention on Climate Change (UNFCCC) has been the establishment of a participatory process for Reducing Emissions from Deforestation and Forest Degradation (REDD+). We analyse the case of Brazil, the country whose land-use emissions from deforestation and forest degradation have declined the most. Through semi-structured interviews with 29 country policy experts – analysed in full text around 7 categories of activities that existing literature identifies as central elements of an effective governance system – we find weak links between the international REDD+ system and what actually happens on the ground inside Brazil. The greatest weaknesses are rooted in the absence of any formal learning system, which prevents higher-level efforts from obtaining useful feedback from lower-level entities responsible for implementation. Analytically our approach is rooted in the idea of ‘experimentalist governance’ in which local policy experiments map the space of what is possible and effective with transformative land policy. These experiments provide information to broader international initiatives on how local implementation shapes the ability and strategy to reach global goals. The Brazilian experience suggests that even when international funding is substantial, local implementation remains a weak link. REDD+ reforms should focus less on the total amount of money being spent and much more on how those funds are used to generate useful local policy experiments and learning.

Key policy insights

• A nascent system of experimentalist governance to implement REDD+ is taking shape in Brazil. However, the potential for experimentalism to improve policy reforms within Brazil is far from realized;

• Experimentalist problem-solving approaches could have a big impact on REDD+ with stronger incentives to promote experimentation and learning from experience;

• Reforms to REDD+ incentive schemes should focus less on the total amount of money being spent and more on whether those funds are actually generating experimental learning and policy improvement – in Brazil and in other countries struggling with similar challenges.

     

Temporal and spatial changes in grain size on a macro-tidal channel-flat complex: results from Kingsport,Nova Scotia,Bay of Fundy

Ocean Dynamics - Understanding the processes that lead to seasonal changes in grain size on muddy macro-tidal flat and channel complexes will assist efforts to predict future changes caused by...     

The structure of the benthic macrofaunal assemblages and sediments characteristics of the Paraguaçu estuarine system, NE, Brazil

The structure of the benthic macrofaunal assemblages of the estuarine portion of Paraguaçu River, NE, Brazil, and its relationship with surface sediment characteristics (trace metals, PAHs, nutrients and grain size) and physical variables were investigated at ten stations on two contrasting occasions, summer (dry season) and winter (rainy season). A total of 1258 individuals (632 in winter and 626 in summer) and 62 taxa representing polychaetes, crustaceans, bivalves, echinoderms, bryozoans, sponges, cnidarians and cephalochordates were collected. Benthic assemblages in the upper estuary were unlike those in the lower estuary and a clear substitution of benthic taxa along the estuary was observed. Macrofaunal invertebrates in the low salinity region, composed of coarse sediments, were dominated by tellinids, venerids (bivalves), cirolanids (isopods), cyclopoids (copepods), and nereidids (polychaetes). While the high salinity region, composed of fine sediments, were dominated by nuculids (bivalves), cirratulids (polychaetes), and by amphiurids (ophiuroids). The Paraguaçu estuarine system is not severely affected by anthropogenic activities. In the great majority of the study sites, concentrations of trace metals and PAHs in the sediments were near background values. Nutrients values were also low. We formulated new models of taxon distribution and suggested detailed studies on the effects of salinity variation and studies using functional approaches to better understand the processes causing the spatial patterns in tropical estuarine benthic assemblages.     

A Chart for Judging Optimal Sample Spacing for Ore Grade Estimation: Part II

Natural Resources Research - Resources of mineral deposits are commonly estimated using data extracted from rock cores obtained by drilling. Information of good quality and quantity is essential to...     

Satellite-derived estimates of potential carbon sequestration through afforestation of agricultural lands in the United States

Afforestation of marginal agricultural lands represents a promising option for carbon sequestration in terrestrial ecosystems. An ecosystem carbon model was used to generate new national maps of annual net primary production (NPP), one each for continuous land covers of ‘forest’, ‘crop’, and ‘rangeland’ over the entire U. S. continental area. Direct inputs of satellite “greenness” data from the Advanced Very High Resolution Radiometer (AVHRR) sensor into the NASA-CASA carbon model at 8-km spatial resolution were used to estimate spatial variability in monthly NPP and potential biomass accumulation rates in a uniquely detailed manner. The model predictions of regrowth forest production lead to a conservative national projection of 0.3 Pg C as potential carbon stored each year on relatively low-production crop or rangeland areas. On a regional level, the top five states for total crop afforestation potential were: Texas, Minnesota, Iowa, Illinois, and Missouri, whereas the top five states for total rangeland afforestation potential are: Texas, California, Montana, New Mexico, and Colorado. Afforestation at this level of intensity has the capacity to offset at least one-fifth of annual fossil fuel emission of carbon in the United States. These projected afforestation carbon gains also match or exceed recent estimates of the annual sink for atmospheric CO₂ in currently forested area of the country.     

Prediction of the long-term performance of abandoned lead zinc mine tailings in a Welsh catchment

In this study we investigated the sulphidic mine tailings from Frongoch and Grogwynion, two abandoned lead zinc mines in mid-Wales, UK. Despite falling within the same ore field the mine waste characterisation has identified differences in the tailings from the two sites. Bulk concentrations range from 10 to 52 g kg^− 1 for Pb, 1.1 to 2.9 g kg^− 1 for Zn in Grogwynion and from 1.0 to 130 g kg^− 1 for Pb, 11 to 110 g kg^− 1 for Zn in Frongoch. An experimental (European standard leaching tests TS 14429 and TS 14405) and geochemical modelling approach was used to study the leaching composition as a function of pH and liquid/solid ratio. There was little correlation between the tailings bulk metal concentrations and the leachate composition, but variations in Pb and Zn concentrations were found to be consistent with control of dissolved Pb and Zn by secondary minerals and the mechanisms of dissolution/precipitation/sorption involving them. Specifically, the Grogwynion mine tailings with near-neutral pH have predominantly lead and zinc carbonates controlling Pb and Zn solubility in the leachates, whereas the Pb and Zn concentrations in Frongoch leachates are best modelled with a surface complexation model for metal sorption to oxyhydroxides. The different speciation results in a greater sensitivity of Grogwynion tailings to acidification with a potential release of Pb in solution up to 10 times higher than in Frongoch, despite similar bulk Pb concentrations. At acid pH, Zn is similarly dissolved to a greater extent in Grogwynion than in Frongoch tailings. There was no evidence of sulphide oxidation during the batch and column leaching tests and the suitability of using these European leaching standards for the characterisation of sulphidic mine waste materials for waste management purposes has been considered.