Broughton Island Research Articles

Frog Reproduction and Community Structure in relation to Water Attributes: Setting the stage to understand effects of Climatic Variables and Climate Change

ABSTRACT As amphibians have declined more than other vertebrates and are important environmental bio-indicators for aquatic ecosystems, we must understand how attributes of such ecosystems affect individual frogs, populations, and multi-species communities. For aquatic-breeding frogs, pond physical/chemical properties influence all life-stages and therefore populations, species, and communities. However, studies have focussed on tadpoles, considered few water variables, and not considered relationships between water attributes and frog populations or communities. Inter-specific differences in how water attributes affect tadpole populations, and hence possibly adult choice of breeding site, should reflect habitats where different species occur, but has been little investigated. We studied the only frog species on Broughton Island, off the east coast of Australia: the threatened Green and Golden Bell Frog Litoria aurea (GGBF); and the widespread and abundant Striped Marsh Frog Limnodynastes peronii (SMF). Suitability of pond breeding habitat, measured by encounter rates during 57 visits over 17 years with different life stages, depended on depth, salinity, pH and temperature, with responses by the two species in essentially opposite directions. For both species, encounter rates increased with increasing depth and with decreasing salinity. Encounter rates peaked at neutral to alkaline pH for GGBF (i.e., 6.8 to 8.0 or higher) and acidic pH for SMF (i.e., 5.5 to 6.0). As water temperature increased, encounter rates increased for GGBF and decreased for SMF. Frog community structure depended on average pond temperature and how it changed over time. If recorded temperature, averaged over the year, was less than 22°C or declined to below this level, the GGBF population, as indexed by numbers of adults observed and occurrences of earlier life stages, was low or declined, while the SMF population was high or increased. This threshold yearly average temperature translates into a required temperature at onset of spring breeding for the GGBF of about 20°C. The GGBF population on the island has declined since 1998, when our study began, due to increased aquatic vegetation and consequent decline in water temperature in major breeding ponds. As ponds are small, manual vegetation removal should reverse the trend. A comprehensive understanding of the biological effects of climate change, past and future, can now be pursued.

Effects of Opuntia stricta on floristic composition and diversity within Broughton Island Nature Reserve, North Coast, New South Wales

Aeolian sand dunes on the Broughton Island are heavily disturbed by nesting birds and invaded by Opuntia stricta (Prickly Pear). Biological control agents do not establish well on exposed coastal systems and thus herbicide treatment is currently the main control, but it is expensive in terms of resource allocation. Invasive species are generally considered by many to be controlled at all cost but in many situations, they are benign or even beneficial. We test if O. stricta causes significant change to the vegetation on aeolian sands on Broughton Island. 40100m2 plots were placed randomly over areas of differing cover of O. stricta. Within these plots additional six subplots of 4m2 were placed. All flora species were scored for cover. Univariate and multivariate analyses were performed testing the effects of O. stricta on floristic composition and species density and turnover. Regression models showed a non-significant (r2=0.95; P=0.0557) negative effect of O. stricta cover on species density at the 100m2 plot size and at the 4m2 scale (r2=0.013; P=0.0858). Global comparison of species density between plots with and without O. stricta at the 4m2 scale was non-significant. Homogenisation occurred (lowered beta diversity) across plots with O. stricta presence at the 4m2 scale. More species had their average cover reduced by O. stricta presence than those that were benefited. The scale at which the investigation was undertaken (4 or 100m2; species density and beta diversity) affected the magnitude and significance of O. stricta on the results obtained. The scale at which investigations are made was found to be of importance. Overall, although negative changes were noted in flora species diversity and homogenisation was apparent the negative impact may not be sufficient to justify the costs and resources needed to control the species which is unlikely to be eradicated from the site.

Fire, humans and climate as drivers of environmental change on Broughton Island, New South Wales, Australia

In Australia, the drivers of precolonial fire regimes remain contentious, with some advocating an anthropogenic-dominated regime, and others highlighting the importance of climate, climatic variability or alternatively some nexus between climate and human activity. Here, we explore the inter-relationships between fire, humans and vegetation using macroscopic charcoal, archaeology and palynology over the last ~5430 cal. year BP from Broughton Island, a small, near-shore island located in eastern Australia. We find a clear link between fire and the reduction of arboreal pollen and rainforest indicators on the island, especially at ~4.0 ka and in the last ~1000 years. Similarities with comparable palaeoenvironmental records of fire in the region and a record of strong El Niño (dry, fire-prone) events supports the contention that climate was a significant influence on the fire regimes of Broughton Island. However, two periods of enhanced fire activity, at ~4000 years BP and ~<600 years BP have weaker links to climate, and perhaps reflect anthropogenic activity. Changes to the fire regime in the last ~600 years corresponds with the earliest evidence of Indigenous archaeology on the island, and coincides with implications that Polynesian people were present in the region. After the mid-Twentieth Century a human-dominated fire regime is also an obvious feature of the reconstructed fire record on Broughton Island.

Increase in Relative Abundance and Size of Snapper Chrysophrys auratus Within Partially-Protected and No-Take Areas in a Temperate Marine Protected Area

Marine Protected Areas (MPAs) are known to contribute towards the conservation of marine biodiversity, particularly targeted fishery species. Snapper Chrysophrys auratus are an important recreational and commercial fish species in New South Wales (NSW), Australia, and despite fishery management for this species, they are considered ‘growth overfished’ in this region. To assess how C. auratus respond to the implementation of an MPA with several no-take and partially protected areas in temperate NSW, we monitored their populations over a decade (2006-2017) using baited remote underwater video systems (BRUVs). Surveys were conducted in the Port Stephens-Great Lakes Marine Park with BRUVs deployed on rocky reefs in depths of 20 – 50 m. Long term seasonal sampling (winter vs summer) was undertaken at two locations (Broughton and Fingal Island), and changes in C. auratus abundance prior to, and eight years after zoning implementation, were assessed between these two locations. In total, we sampled five no-take areas within the marine park and five comparative nearby partially protected fished areas and three sites located outside the marine park boundaries. The most pronounced changes in abundance and size structure for C. auratus were observed in the Broughton Island no-take area where numbers increased almost 3-fold (2.91 times) over 8 years of protection. Relative abundance showed seasonal variation at two locations, and we consistently recorded increasing abundance within no-take areas at Broughton and Fingal Island compared to nearby sites open to fishing. Surveys across the five no-take areas found a significant increase in the abundance of C. auratus, whilst the five partially-protected locations in the marine park still recorded higher abundances than sites outside the marine park. In addition, length measurements from stereo-BRUVS indicated that C. auratus were significantly larger in no-take areas compared to partially-protected areas in the marine park and sites outside the marine park. This study demonstrates how the implementation of the marine park and the protection afforded by no-take and partially-protected areas provides refuge for this important fishery targeted species.

A tale of two islands: Decadal changes in rocky reef fish assemblages following implementation of no-take marine protected areas in New South Wales, Australia

Marine Protected Areas (MPAs) are used worldwide as a management tool for the protection of marine biodiversity. To assess decadal changes in rocky reef fish assemblages following MPA protection, fish assemblages were monitored regularly in the Port Stephens-Great Lakes Marine Park (PSGLMP), New South Wales, Australia, using Baited Remote Underwater Video (BRUVs) comparing between fished and non-fished zones. Spatial and temporal heterogeneity of fish assemblages and fishery targeted species were assessed from 2006–2016 at two no-take zones at Broughton and Fingal Islands, and compared with nearby fished areas. A total of 102 species from families was observed over the study, with fish assemblage response being dependent on both the spatial scales of MPA zoning and locations within the park, and the temporal scales assessed. Five fishery targeted families, Labridae, Scorpaenidae, Sparidae, Monacanthidae and Cheilodactylidae, increased in relative abundance within no-take zones, compared with fished zones, although the response was variable among families and between locations. While abundance increased at both locations following the implementation of no-take zones, a significant zoning effect was only detected at Broughton Island, with the Labridae and Sparidae displaying the greatest increases in relative abundance within the no-take zone. This study demonstrates that the response of fish assemblages and targeted fishery families to the implementation of no-take MPA zones varies both temporally, and between locations. Differences in the assemblage response between locations are likely driven by the size and habitats within the no-take zones and these factors need to be adequately considered in MPA planning.

Identification of Potential Foraging Areas for Bowhead Whales in Baffin Bay and Adjacent Waters

The bowhead whale (Balaena mysticetus) is the Arctic’s largest and most dependent predator on zooplankton; however, knowledge about its important foraging areas in Baffin Bay and adjacent waters is limited. Data on movement, horizontal velocity (ms-1), dive depth (m), and dive rate (dives h-1) were obtained from 39 bowhead whales (31 females, 6 males, and 2 of undetermined sex) instrumented with satellite-linked time-depth recorders (SLTDRs) in spring 2009 and 2010 in Disko Bay, West Greenland. Thirty-eight whales provided information on dive rates and movement, and potential foraging areas were identified on the basis of low dive rates and stationary behaviour. Nine potential foraging areas were identified: Disko Bay and adjacent region, Clyde Inlet, Isabella Bay, Broughton Island, Cumberland Sound, Frobisher Bay, Hudson Strait, southern Foxe Basin, and northern Foxe Basin. Two females returned to Disko Bay the following spring (duration of tags > 420 days). Their diving behavior indicated that all whales exhibited a large degree of flexibility in their use of potential feeding areas in Baffin Bay and adjacent waters. The variability of habitat selection may buffer against climate-induced changes in the preferred habitats of bowhead whales.

Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

The first comprehensive geological map, a summary of lithologies and new radiogenic isotope data (U–Pb, Rb–Sr) are presented for crystalline rocks of the Sub-Antarctic Snares Islands/Tini Heke, 150 km south of Stewart Island. The main lithology is Snares Granite (c. 109 Ma from U–Pb dating of zircon), which intrudes Broughton Granodiorite (c. 114 Ma from U–Pb zircon) on Broughton Island. Rafts of schist within Snares Granite are common on the outlying Western Chain islets, and rare on North East and Broughton islands. Zircon grains extracted from one schistose raft on Broughton Island are prismatic and yield an essentially unimodal age population of c. 116 Ma that is within error of the granodiorite. These properties suggest that the dated raft represents a meta-igneous rock despite its mica-rich nature. Some schistose rocks on the Western Chain contain coarse relict plagioclase phenocrysts and appear to have an igneous protolith. No conclusive metasedimentary rocks have been identified, although sillimanite-bearing mica-rich schist occurs on Rua. Deformation of the crystalline rocks occurred after Snares Granite intrusion and before cooling below muscovite K–Ar closure at 400 ± 50 °C at 95 Ma. This period overlaps the age of extensional ductile shear zones on Stewart Island. The discovery of several basaltic dykes, which cut across fabrics and are unmetamorphosed, indicates that volcanic rocks are associated with all Sub-Antarctic island groups. The larger of the islands are overlain by peat, which on North East Island also contains gravel deposits.

A successful long-distance aerial pursuit of an Australian Raven Corvus coronoides by a Brown Goshawk Accipiter fasciatus

The Brown Goshawk Accipiter fasciatus has a variable diet comprising mainly avian prey and mammals, and most observations suggest that it employs a range of ambush tactics but rarely uses long-distance aerial pursuits. Here I document a rare instance of a successful long-distance aerial pursuit of an Australian Raven Corvus coronoides by a Brown Goshawk, on 29 March 2015, on Broughton Island, New South Wales. After multiple unsuccessful aerial attacks, the Goshawk eventually succeeded. Although corvids are abundant and widespread throughout Australia and are within the preferred avian prey size range, they are rarely observed in the Goshawk’s diet. Two ecological factors probably contributed to this observation: (1) there is little woodland here and thus little concealment for ambush tactics and (2) prey availability on Broughton Island and the surrounding islands has been altered by programs to eradicate pest mammals, thereby limiting the prey available to this species in this area.

The Winter Infection of Sea Lice on Salmon in Farms in a Coastal Inlet in British Columbia and Possible Causes

An increase in infections with two species of sea lice occurred on farmed salmon farthest up an inlet in the Broughton Island area of British Columbia during the winter of 2005/2006. The increase in the chalimus stage started at the end of November 2005 at a rate of 0.03 lice/day for Lepeophtheirus salmonis and 0.015 lice/day for Caligus clemensi. The increase in the infection started at a time of high salinity and low sea surface temperatures with very few gravid sea lice detected on the farmed fish. The mobile stages increased in early January about one month after the increase in the chalimus stage. Gravid lice increased in abundance about the time the farmed fish were treated with SLICE® in early February. This pattern of an increase in infection in the winter was similar in two nearby farms. In January of 2008 the three farms in the study area were either treated with SLICE® or the fish were harvested. Despite the reduced capacity of the salmon farms to produce sea lice, the juvenile stages remained abundant on sticklebacks ( Gasterosteus aculeatus ) around the farms in February and March of 2008. Sticklebacks were heavily infected with sea lice but were not a host of gravid lice. Trawl studies in the vicinity of the farms did not find an abundance of hosts except for sticklebacks. Some of the infection on the sticklebacks could originate from a low level of gravid lice on the farmed fish in the study area. However, we speculated that a major source of the winter infection on the sticklebacks could result from the transport of infectious stages in the deeper water that flows into the area as a consequence of the estuarine circulation. The source of these lice and the lice in the 2005/2006 study could be natural or from untreated fish farms farther down the inlet or both. Continued research is needed to understand the biology and population ecology of both species of sea lice in order to manage their production

Assessing daytime downward longwave radiation estimates for clear and cloudy skies in Southern Brazil

Several well-known parameterisations for clear-sky and cloudy-sky downward longwave radiation were tested for an experimental site at Ponta Grossa (Paraná State, Brazil) where all radiation components and meteorological data were measured during 279 days in spring, summer, fall and winter (2003/2004). The existing clear-sky parameterisations usually overestimate the measured values, whereas the cloudy-sky formulations underestimate measurements. Best results for clear-sky downward longwave radiation were obtained with Brutsaert's [Brutsaert, W.H., 1975. On a derivable formula for long-wave radiation from clear skies. Water Resour. Res. 11 (5), 742–744] formulation. Jacobs’ [Jacobs, J.D., 1978. Radiation climate of Broughton Island. in: Barry, R.G., Jacobs, J.D. (Eds.), Energy budget studies in relation to fast-ice breakup processes in Davis Strait. Inst. of Arctic and Alp. Res. Occas. Paper No. 26. University of Colorado, Boulder, CO, pp. 105–120] and Crawford and Duchon's [Crawford, T.M., Duchon, C.E., 1999. An improved parameterization for estimating effective atmospheric emissivity for use in calculating daytime downwelling longwave radiation. J. Appl. Meteorol. 38, 474–480] equations gave the best results for cloudy skies. The parameterisations that generated the best fits were further locally calibrated, providing a useful tool for applications requiring downward longwave radiation estimates in Southern Brazil. No significant differences between spring/summer and autumn/winter were found for the coefficients of the Brutsaert's clear-sky parameterisation, whereas some seasonality may be present in Jacobs’ cloudy-sky parameterisation. For practical purposes, however, little is gained in error reduction, and it is sufficient to use year-round calibrated coefficients.

The vegetation of The Snares, islands south of New Zealand, mapped and discussed

A map of the main vegetation communities on The Snares, southern New Zealand, is presented based on stereo‐aerial photographs taken by the RNZAF followed by ground checks during the University of Canterbury's summer expedition, 1969/70. The physiognomic dominant species are the daisy trees Olearia lyallii and Brachyglottis stewartiae, the coastal shrub Hebe elliptica, the maritime grasses Poa astonii and P. tennantiana, and the megaherb Stilbocarpa robusta. Other indigenous vascular plants present include: four ferns, six dicotyledons, and five monocotyledons. Poa annua and Stellaria media are the only adventives which are local. Olearia forest is the principal community, covering some 52% of Main Island and about 18% of Broughton Island. Maritime tussock grassland covers 27% of Main Island and 41% of Broughton. Locations of the uncommon large aniseed Anisotome acutifolia are highlighted. Data on climate, some vegetation changes, and the effects of seabirds on the plant communities are given.

Population size and trends within the two populations of Southern Buller's Albatross Diomedea bulleri bulleri

The abundance and distribution of Southern Buller's Albatross ( Diomedea bulleri bulleri) were investigated at the Solander Islands in February 1996 and at The Snares in March 1997. The total breeding population of this endemic subspecies was estimated at 11 502 breeding pairs. At the Solander Islands, a total of 2625 occupied nests was estimated from aerial and ground counts in the first accurate census that included all islands in the group. Comparisons with the number of chicks counted on Little Solander Island in 1985 indicated a possible decrease of 18.7% or no change in the numbers of breeding pairs during the period 1985–1996. At The Snares, a total of 8242 occupied nests was counted and a further 635 were estimated on North East Island, Broughton Island, and associated islets and stacks. A comparison with the numbers of occupied nests counted on North East Island, The Snares, during 1969 and 1992 indicated population increases of 78% and 8% during the periods 1969–1992 and 1992–1997, respectively. Differences in the rates of change within The Snares population demonstrate the complexity of population parameters within a single seabird species, thus emphasising the need for careful formulation of conservation measures.

Climate and cultural barriers to northern economic development: a case study from Broughton Island, N.W.T., Canada

It is critical to study cllmate and cultural factors Influencing the handicraft industry in order to combat cntlcal levels of unemployment in northern settlements. The purpose of thls paper is to Identify the climate and cultural factors influencing production at the Minnguq Sewing Group in Broughton Island, Northwest Territories, Canada Participatory action research methods, including participation In workshops, observing the decision making processes, and Informal Interviews were used during the field research conducted from January to August 1991. Information was collected on vanous aspects of business including product 11ne development, production techniques, management strategies, and fundlng sources. Cllmate and culture influenced availability of resources, funding, and tralning, isolation from consumers and supplies; and ~ntegration of new technology. This study wlll be of interest to scientists studying rural economy, abonginal economlc development, internatlonal arts and crafts, cross-cultural clothing, histoncal clothing, and other related fields.

High levels of PCBs in breast milk of inuit women from arctic quebec

In the last twenty years polychlorinated biphenyls (PCBs) have been identified as major contaminants of the natural environment. More recently, the presence of such toxic compounds was described in arctic regions. In this regions, PCBs have been found in water, snow, ice and air. The level of PCB contamination was significantly lower than that found at midlatitudes. PCB levels are often monitored because they could also reflect exposure to several other chemical contaminants such as other organochlorines. Other highly toxic compounds such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were found in the blubber from arctic ringed seals caught near the west coast of Spitzbergen. Since the closest known sources of PCDD and PCDF were several thousands of kilometers away, these results were surprising. The consumption of fish and marine mammals by the Inuit people is markedly higher than in the rest of the Canadian population and in some communities, sea mammals represent a significant part of the diet. It is possible that Inuit are exposed to an undesirably high of PCBs and other organochlorinated compounds. Levels of PCBs in the Inuit diet were assessed in Broughton Island, North West Territories, Canada. The present study was designed to assess themore » PCB levels in the breast milk of lactating Inuit women from the Hudson Bay region of Northern Quebec and of women from Southern Quebec.« less

Stratigraphy, amino acid geochronology, and correlation of Quaternary sea-level and glacial events, Broughton Island, arctic Canada

Raised marine and glaciomarine terraces on Broughton Island record regional isostatic adjustments and eustatic sea-level changes. Previous workers proposed three alternative glacial and sea-level chronologies of the region. These conflicts are resolved by the stratigraphic control provided by amino acid ratios (D-allo-isoleucine/L-isoleucine) in marine molluscs collected form cliff exposures. Amino acid ratios, radiometric dates, and relative weathering measurements on geomorphological features provide a basis for regional correlations.Based upon amino acid ratios, the coastal sedimentary sequences, all part of the Broughton Island Formation, can be subdivided into six units to which informal member names have been assigned. These units delimit at least four glacial episodes during which local ice advanced around Broughton Island to the outer coast. The youngest advance is correlative with deposits that are dated > 54 000 BP, and the absolute ages of older events have been estimated from minimum uranium-series dates and amino acid data. Glacial events previously recognized as the Foxe Glaciation represent a much greater portion of the Quaternary than was previously realized.The Tuneek member, the oldest sedimentary unit on Broughton Island, consists of a bouldery, sandy clay diamicton deposited by a major pre-Foxe glacial advance(s) that occurred possibly > 500 000 years BP when ice traversed the island. Subsequent advances were deflected along the southern coast of the island through Broughton Channel. The Anigatalik member, estimated to be between 300 000 and 500 000 years old, consists of a variety of sediment types including bouldery clay diamictons and bedded, coarse sands and gravels. The Platform member represents a subsequent and extensive pre-Foxe glacial advance. It consists of a bouldery, shelly till deposited over a wave-cut platform at the north end of Broughton Island between 250 000 and 350 000 years BP. Correlative tills were deposited along the east coast by glacial ice extending around the southeast corner of the island. Relative sea level was at least 72 m asl during this time.The Cape Broughton member consists of ice-proximal sediments deposited when fiord ice was retreating from Broughton Channel approximately 150 000 – 200 000 years BP. The macrofauna and microfauna within these sediments suggest that subarctic water masses, warmer than present, were adjacent to the northeastern Baffin coast subsequent to the glacial maximum. These deposits may be correlative with a prominent moraine system on either side of Broughton Channel.The Harbour member represents the beginning of the Foxe Glaciation (as it is redefined) and delineates the last major advance of ice to the outer coast. The current best estimate for the age of these sediments is 70 000 – 130 000 years BP. At one locale, Harbour sediments overlie an organic-rich, oxidized horizon containing a pollen assemblage strongly indicative of interglacial conditions. The stratigraphy suggests that a major interglacial period preceded the Harbour advance. Organic horizons near the top of the Harbour member contain a pollen assemblage that suggests a terrestrial climate similar to that of today.The Matsaja member consists of nearshore marine sands and beach facies deposited by an early Holocene transgression to between 7 and 8 m asl that occurred approximately 8000 – 10 000 years BP. A minor transgression of 1–2 m commenced approximately 1000 years BP.

The Broughton Trough on the continental shelf of eastern Baffin Island, Northwest Territories

Bathymetric and seismic surveys of the trough across the continental shelf of Baffin Island at Broughton Island indicate that there were four stages in its development. The first involved deposition of Cretaceous and early Tertiary marine sediments before and during formation of a graben associated with the opening of Baffin Bay. With the uplift of Baffin Island, extensive deltaic deposits at the distal end of the trough were laid down in the second stage. These deposits are thought to represent the products of a river system raised much above grade, flowing in the trough and the fiords to the southwest, and depositing in a sea with a relative level 300–400 m below present. In the third stage during Pliocene–Pleistocene glaciation, the proximal regions of the trough were eroded to more than 700 m below present sea level. Lateral moraines indicate the extension of ice to the edge of the continental shelf, although the relatively small amount of erosion in the distal region suggests that the ice may have been partially floating. Glaciomarine and marine sedimentation following glaciation is the final stage in the evolution of the trough.

Microbiostratigraphy of young Cenozoic marine deposits of the Qivituq Peninsula, Baffin Island

Analysis of assemblages of fossil foraminifera in sediment samples from the wave-cut cliff of the Qivituq Peninsula on the northeast coast of Baffin Island, Arctic Canada, made possible a stratigraphical subdivision of the deposits into nine assemblage zones indicated by letters from zone A, youngest, to zone I, oldest. The paleoecological inference of these zones is discussed and correlation with other stratigraphical units in Baffin Island, viz., at Broughton Island and Clyde Foreland, is carried out. Comparison of 14C-dated and micropaleontologically investigated deposits in Baffin Island with 14C-dated and micropaleontologically distinguished units of the Arctic Soviet Union indicate a Pleistocene age for zones C through F of the Qivituq Peninsula, for the Islandiella islandica zone of the Clyde Foreland Formation, and for the so-called Cape Broughton Interstadial deposits of Broughton Island. Comparison of foraminiferal assemblages of the zones H and I of the Qivituq Peninsula and of the Cibicides grossa zone and the Nonion tallahattensis zone of the Clyde Foreland Formation with foraminiferal assemblages in material from deep borings in the North Sea indicate a Late Tertiary, most probably Pliocene, age for these zones. Zone G of the Qivituq Peninsula and the Cassidulina teretis zone of the Clyde Foreland Formation may form transitional units between the Tertiary and the Quaternary. 14C-dates indicate a Holocene age for zones A and B of the Qivituq Peninsula.

A program package for interactive design of optimal pipe networks for any climatic region in Canada

The program package presented in this paper facilitates the computer-aided design of least-cost pipe distribution networks for any region in Canada. The design algorithms function in an interactive, conversational mode. Three algorithms—for analysing pressure and flow in networks, for computing the 'best' diameter of each pipe in the network, and for computing the best sizes of devices and materials to protect the pipes against freezing—were combined. Here 'best' is taken to be the least equivalent average annual cost.The pipe distribution network may include a wide variety of pipeline components and environmental constraints. The variables that determine the cost of pipe distribution networks in the extreme climatic regions of Canada are identified and their interaction for the many combinations of environmental, economic, and technological constraints are described.The computer program package was employed in the design of a minimum-cost distribution system for Broughton Island, Northwest Territories. The performance of the package indicated that it could be reliable, easy to use, and competitive in design cost.The package is locally accessible through a national computer network to dial-up terminals in or near most cities in North America.

Synoptic controls on the energy budget regime of an ablating fast ice surface

Energy budget studies over fast ice were carried out near Broughton Island N.W.T. from June 13 to July 20, 1972. Turbulent flux calculations have been performed via an aerodynamic profile approach. Two clearly differentiated energy budget regimes can be related to the stage of decay of the fast ice. The division between the two regimes occurs at the beginning of July. Cluster analysis has been used to group together days with similar turbulent flux characteristics within each of these two regimes. In each set one group of days was found that tends to advance, and another that tends to retard, the snow or ice ablation. These groupings are found to be statistically significant. The groups in each regime can also be differentiated in terms of pressure patterns, direction of airflow and average temperature.

Energy balance and ground thermal regime studies broughton Island, Northwest Territories, Canada

This paper examines the relationship between energy balance and ground thermal regime over a variety of tundra surfaces in a low arctic environment. The Bowen ratio and energy balance data emphasized the dominance of latent heat fluxes over the freely evaporating terrain. The sensible heat flux was negative, owing to persistent surface inversions, and supplied energy for evaporation. The ground heat flux was minimal until July 6 and the major increase on that date resulted in a sharp rise in the rate of ground thawing. The deepest measured penetration (80 cm) was achieved in moist sandy soil, compared with 50 cm depth in adjacent clay loam, despite the similarity between Bowen ratios at both sites. Energy balance data do not account for active layer variations and independent soil factors appear to exert the major control on ground ice melt. The paper concludes with a discussion of Bowen ratios and energy balance at the study area vis-a-vis other snowfree tundra environments.