Canada's Atlantic Coastal Action Program: A community-based approach to collective governance

The Atlantic Coastal Action Program (ACAP) is a community-based coastal management initiative that has been underway on Canada's east coast for the past 6 years. Coalitions of local stakeholders have been assisted by government in taking a lead role for the planning and management activities in 13 coastal ecosystems throughout Atlantic Canada. The program was initiated and originally facilitated by the federal government (Environment Canada) but has come to be led and owned at the local level. The objective is to have all those affecting and/or affected by local decisions involved in this process. In ACAP, the traditional role of government is shared with the local roundtables that are established in each coastal ecosystem. Instead of government departments being the lead agencies that set policy and priorities, the communities assume this function and the government agencies become partners in responding to their identified needs. ACAP is a practical demonstration of the joint management, or collective governance approach to Integrated Coastal Management and offers lessons to governments and coastal communities looking to establish lasting partnership approaches that have the potential to achieve the sustainable development of coastal ecosystems.     

Invertebrate fossils (Insecta: Trichoptera,Diptera, Coleoptera) from the Pleistocene Scarborough Formation at Toronto,Ontario, and their paleoenvironmental significance

Larval caddisfly, chironomid, and beetle remains have been recovered from the Pleistocene Scarborough Formation in the Toronto region of southern Ontario. Three stratigraphic levels were sampled at the northeastern end of the Scarborough Bluffs; the youngest horizon yielded 16 chironomid taxa, 33 caddisfly taxa, and 28 beetle taxa, whereas the two older levels yielded somewhat less diverse assemblages. Only one taxon in each of the caddisfly and chironomid groups was identified from the presumed correlative beds at Woodbridge, Ontario, but numerous beetle fragments were recovered, several of which have been specifically identified and match species found previously in the upper part of the Scarborough Formation. The youngest sampled assemblage in the Scarborough Formation at the northeastern end of the Scarborough Bluffs is interpreted as indicating cool climatic conditions in a boreal forest environment, given the present-day distributions and feeding habits of these river, lake, and terrestrial taxa. The mean July temperature at this time was probably about 15°C, as compared to the present-day value of 20.5°C. The forest was poorer in deciduous species during deposition of the older part of the formation as preserved here. These results agree well with previous interpretations based on plant remains. We suggest that both aquatic and terrestrial insects are good indicators of macroclimate.     

A spatial and temporal drought risk assessment of three major tree species in Britain using probabilistic climate change projections

Probabilistic climate data have become available for the first time through the UK Climate Projections 2009, so that the risk of change in tree growth can be quantified. We assessed the drought risk spatially and temporally using drought probabilities calculated from the weather generator data and tree species vulnerabilities using Ecological Site Classification model across Britain. We evaluated the drought impact on the potential yield class of three major tree species (Picea sitchensis, Pinus sylvestris, and Quercus robur), which cover around 59 % (400,700 ha) of state-managed forests, across the lowlands and uplands. We show that drought impacts result mostly in reduced tree growth over the next 80 years when using B1, A1B, and A1FI IPCC emissions scenarios, but varied spatially. We found a maximum reduction of 94 % but also a maximum increase of 56 % in potential stand yield class in the 2080s from the baseline climate (1961–1990). Furthermore, potential production over the state-managed forests for all three species in the 2080s is estimated to decrease due to drought by 42 % in the lowlands and by 32 % in the uplands in comparison to the baseline climate. Our results reveal that potential tree growth and forest production on the state-managed forests in Britain is likely to reduce, and indicate where and when adaptation measures are required. Moreover, this paper demonstrates the value of probabilistic climate projections for an important economic and environmental sector.     

Intraspecific Interactions and Risk of Predation for Dyspanopeus sayi (Decapoda: Xanthidae) Living on Polychaete (Filograna implexa,Serpulidae) Colonies*

Abstract. Along the Atlantic coast of the United States, the mud crab Dyspanopeus sayi frequently occurs in crevices and depressions within aggregated calcareous tubes (termed “heads”) of the serpulid polychaete Filograna implexa. In New Jersey, U.S.A., waters, crab number was significantly correlated with the logarithm of worm tube colony volume. Laboratory experiments suggested that crabs compete for shelter within worm colonies. Additional laboratory experiments indicated that colony occupancy greatly decreased the risk of predation by blue crabs (Callinectes sapidus), and field tethering experiments also demonstrated that colony occupancy significantly decreased predation risk. Thus, the consequence of holding space on worm tube heads is a greatly increased probability of survival.     

Breaking rocks made easy. Blending stress control concepts to advance geomorphology

All landscapes are subject to stress fields, conditioned by their formation and ongoing tectonic and geomorphic changes. With this ESEX Commentary we wish to stimulate a debate on this invisible but persistent stress control on landforms, processes and materials in geomorphology. We address the legacy of active and passive stress fields, which translates into the concept of ‘tectonic predesign’, in conjunction with a perspective of geomorphic processes being driven by subcritical stresses. These concepts complement each other as ‘subcritical processes’ are controlled by tectonic predesign and in turn modulate the stress fields. This offers new theoretical and practical perspectives on how landscapes evolve, processes form materials and how rocks break easily. © 2018 John Wiley & Sons, Ltd.     

Carbon Cycling and the Coupling Between Proton and Electron Transfer Reactions in Aquatic Sediments in Lake Champlain

We used fine-scale porewater profiles and rate measurements together with a multiple component transport–reaction model to investigate carbon degradation pathways and the coupling between electron and proton transfer reactions in Lake Champlain sediments. We measured porewater profiles of O₂, Mn²⁺, Fe²⁺, HS⁻, pH and pCO₂ at mm resolution by microelectrodes, and profiles of NO₃ ⁻, SO₄ ²⁻, NH₄ ⁺, total inorganic carbon (DIC) and total alkalinity (TA) at cm resolution using standard wet chemical techniques. In addition, sediment–water fluxes of oxygen, DIC, nitrate, ammonium and N₂ were measured. Rates of gross and net sulfate reduction were also measured in the sediments. It is shown that organic matter (OM) decomposes via six pathways: oxic respiration (35.2%), denitrification (10.4%), MnO₂ reduction (3.6%), FeOOH reduction (9.6%), sulfate reduction (14.9%), and methanogenesis (26.4%). In the lake sediments, about half of the benthic O₂ flux is used for aerobic respiration, and the rest is used for the regeneration of other electron acceptors produced during the above diagenetic reactions. There is a strong coupling between O₂ usage and Mn²⁺ oxidation. MnO₂ is also an important player in Fe and S cycles and in pH and TA balance. Although nitrate concentrations in the overlying water were low, denitrification becomes a quantitatively important pathway for OM decomposition due to the oxidation of NH₄ ⁺ to NO₃ ⁻. Finally, despite its low concentration in freshwater, sulfate is an important electron acceptor due to its high efficiency of internal cycling. This paper also discusses quantitatively the relationship between redox reactions and the porewater pH values. It is demonstrated here that pH and pCO₂ are sensitive variables that reflect various oxidation and precipitation reactions in porewater, while DIC and TA profiles provide effective constraints on the rates of various diagenetic reactions.     

Stratoid granites of Madagascar: structure and position in the Panafrican orogeny

Abstract

Stratoid granites constitute a major feature of the Precambrien basement of Madagascar. A detailed structural study was carried out NNW of Antananarivo. New zircon isotopic data on a typical alkaline granite ascertain their Panafrican age (585 Ma). The sheets of granites metric to kilometric of thickness, are interlayered with migmatitic gneisses and amphibolites. Their internal structures, determined by anisotropy of magnetic susceptibility measurements, everywhere yield foliations gently dipping to the west, and lineations striking WSW-ENE. These structures were mostly acquired at the magmatic stage in the granites, in the country-rocks they resulted from high-temperature plastic deformation.

The very constant structural pattern, interpreted in terms of shear deformation of a section of the crust, as well as the low P (P = 4 - 5 kb) - high T (T # 750°C) conditions, suggest that the emplacement of the stratoid granites was coeval with a late-orogenic stage in the Panafrican Mozambique belt, and possibly linked to the thinning of the lithosphere.     

Effects of Increased Salinity and Inundation on Inorganic Nitrogen Exchange and Phosphorus Sorption by Tidal Freshwater Floodplain Forest Soils, Georgia (USA)

We investigated the effects of increasing salinity and inundation on inorganic N exchange and P sorption/precipitation in soils of tidal freshwater floodplain forests (TFFF) of coastal Georgia, USA. Our objectives were to better understand how sea level rise, increasing inundation, and saltwater intrusion will affect the ability of TFFFs to retain nitrogen (N) and phosphorus (P). We collected soil cores (0–5 cm) from three TFFFs that do not currently experience saltwater intrusion and from one TFFF currently experiencing saltwater intrusion and measured NH₄-N exchange and PO₄-P removal over five simulated 6-h tidal cycles using nutrient-enriched freshwater (30 μM NH₄-N and 5 μM PO₄-P). In a second experiment, we exposed soil cores to three salinities (0, 2, and 5) and two inundation depths (5 and 10 cm) using the same nutrient enrichment. When flooded with nutrient-enriched freshwater, soils from the three TFFFs that do not experience saltwater intrusion removed inorganic N and P in amounts ranging from 5.2 to 10.7 and 2.3 to 4.4 mg/m², respectively, and the TFFF soils experiencing saltwater intrusion removed 2.1 to 3.8 mg P/m². However, TFFF soils experiencing saltwater intrusion released inorganic N to the water column in amounts ranging from 7.1 to 67.5 mg/m². In the second experiment, soils from TFFFs not experiencing saltwater intrusion released NH₄-N to the water column when exposed to 2 and 5 salinity, and the amount of N released increased with salinity and number of tidal cycles. In contrast, the same TFFF soils sorbed two and three times more PO₄-P when exposed to 2 and 5 salinity than when exposed to 0 salinity. P removal on a mass basis was greater under 10 cm of inundation, but the efficiency of removal was greater under the 5 cm flooding depth. Our findings suggest that saltwater intrusion caused by sea level rise will promote N release into the water column through organic matter mineralization and/or ion exchange and may promote P sorption, or precipitation of P with metal cations. In addition, release of N and resulting increased N/P could exacerbate eutrophication of estuaries in the future.     

Lake sediment cores as indicators of historical metal(loid) accumulation – A case study in Mexico

To examine and compare historical accumulation of metal(loid)s in Mexican lakes and reservoirs, ²¹⁰Pb and ¹³⁷Cs dated sediment cores were evaluated: two from the remote Zempoala and Miramar Lagoons and three from Lake Pátzcuaro, and the Intermedia and Silva dams that are affected by human activities. Sediment ecotoxicology was assessed using consensus-based sediment quality guidelines for freshwater ecosystems. The +100 a sediment core from the remote Miramar Lagoon had the highest concentrations of Cr and Ni these being higher than the Probable Effect Levels (PELs). Zinc concentrations were also higher in the Miramar Lagoon compared to the other lakes and reservoirs, with concentrations higher than the Threshold Effect Level (TEL). Mercury concentrations from this lagoon were comparable to those for the Intermedia dam that receives water from urban, industrial and agricultural areas. The higher metal concentrations in the core from the Miramar Lagoon suggest that metal concentrations in the rocks of the watershed are high. Another explanation for the higher metal concentrations is the slow sediment accumulation that causes metals to be accumulated over longer time-periods at the sediment–water interface. A decrease in the concentration of As in the Intermedia dam was observed in sediments corresponding to the last decades. This may be due to an increase in sediment accumulation rate or to the reduction in sources of this metalloid in the watershed. In the Miramar Lagoon, an increase was observed in concentrations of As and Cr in more recent sediments, probably related to increased deforestation in the area or the eruption of El Chichonal volcano in 1982. Concentrations of Pb showed a decreasing tendency over the past decades in the Lake Pátzcuaro, Miramar and Zempoala Lagoons sediment cores while such behavior was not be observed for the Intermedia dam. This reduction in concentrations of Pb was attributed to the decrease in use of leaded gasoline.