In my back yard

In My Back Yard is a documentary film that explores the changing landscape of the Mount Dennis neighbourhood in Toronto. This change is represented by the 54-acre Kodak site that is being transformed into the second largest transportation hub in the Greater Toronto Area. The film employs a series of visual strategies and retells recent observations related to the impact of this massive infrastructure project on the people, the land and the urban wildlife. Local residents, politicians and community leader were consulted. Their interviews are combined with dioramas, archival photographs and time-lapse photography to express the multi-facetted list of community concerns. This support paper attempts to define and analyse these struggles within the context of Leo Marx’s 1964 work The Machine in the Garden: Technology and the Pastoral Ideal in America. This paper proposes that Marx’s concept of the “middle landscape” helps to define the current struggle in Mount Dennis.

In my back yard

In My Back Yard is a documentary film that explores the changing landscape of the Mount Dennis neighbourhood in Toronto. This change is represented by the 54-acre Kodak site that is being transformed into the second largest transportation hub in the Greater Toronto Area. The film employs a series of visual strategies and retells recent observations related to the impact of this massive infrastructure project on the people, the land and the urban wildlife. Local residents, politicians and community leader were consulted. Their interviews are combined with dioramas, archival photographs and time-lapse photography to express the multi-facetted list of community concerns. This support paper attempts to define and analyse these struggles within the context of Leo Marx’s 1964 work The Machine in the Garden: Technology and the Pastoral Ideal in America. This paper proposes that Marx’s concept of the “middle landscape” helps to define the current struggle in Mount Dennis.

Effects of dead conspecifics, hunger states, and seasons on the foraging behavior of the purple urchin Heliocidaris crassispina

Trophic cascades are a powerful result of predator-prey relationships in an ecosystem. In aquatic environments, the signals associated with predators and predation are used by prey as a cue to avoid encountering predators when foraging for food. These behavioral cues can be powerful enough to control prey populations and indirectly protect primary producers. Here, we evaluated the effects of cues associated with predation on the purple urchin Heliocidaris crassispina and examined effects of hunger state and season, using time-lapse photography. A series of laboratory and in situ manipulative experiments were conducted to determine patterns of foraging behavior and behavioral modifications. We showed that starved urchins were less sensitive to predation cues compared to normally fed urchins. Field experiments indicated that 70% of fed urchins fled when exposed to a predation cue (presence of a dead urchin) whereas starved urchins remained regardless of the cue, supporting results from the laboratory using dead urchin and algal cues. Sea urchin activity and feeding rates were lower in winter-spring than in summer-autumn. Results suggest that hunger state has a large influence over the behavioral response of sea urchins, while also being affected by season due to metabolic control. In general, starvation appears to override predator avoidance behaviors, which exposes prey species to higher risks of predation.

Buoyant calving and ice-contact lake evolution at Pasterze Glacier (Austria) in the period 1998–2019

Rapid growth of proglacial lakes in the current warming climate can pose significant outburst flood hazards, increase rates of ice mass loss, and alter the dynamic state of glaciers. We studied the nature and rate of proglacial lake evolution at Pasterze Glacier (Austria) in the period 1998–2019 using different remote-sensing (photogrammetry, laser scanning) and fieldwork-based (global navigation satellite system – GNSS, time-lapse photography, geoelectrical resistivity tomography – ERT, and bathymetry) data. Glacier thinning below the spillway level and glacier recession caused flooding of the glacier, initially forming a glacier-lateral to supraglacial lake with subaerial and subaquatic debris-covered dead-ice bodies. The observed lake size increase in 1998–2019 followed an exponential curve (1998 – 1900 m2, 2019 – 304 000 m2). ERT data from 2015 to 2019 revealed widespread existence of massive dead-ice bodies exceeding 25 m in thickness near the lake shore. Several large-scale and rapidly occurring buoyant calving events were detected in the 48 m deep basin by time-lapse photography, indicating that buoyant calving is a crucial process for the fast lake expansion. Estimations of the ice volume losses by buoyant calving and by subaerial ablation at a 0.35 km2 large lake-proximal section of the glacier reveal comparable values for both processes (ca. 1×106 m3) for the period August 2018 to August 2019. We identified a sequence of processes: glacier recession into a basin and glacier thinning below the spillway level; glacio-fluvial sedimentation in the glacial–proglacial transition zone covering dead ice; initial formation and accelerating enlargement of a glacier-lateral to supraglacial lake by ablation of glacier ice and debris-covered dead ice forming thermokarst features; increase in hydrostatic disequilibrium leading to destabilization of ice at the lake bottom or at the near-shore causing fracturing, tilting, disintegration, or emergence of new icebergs due to buoyant calving; and gradual melting of icebergs along with iceberg capsizing events. We conclude that buoyant calving, previously not reported from the European Alps, might play an important role at alpine glaciers in the future as many glaciers are expected to recede into valley or cirque overdeepenings.

Tidal monitoring on sandy beaches using perpendicular time-lapse photography

<p><span>Long term time-lapse photography has proven to be a key tool in monitoring changes in coastal environments, particularly in terms of morphology. The present study adapts and simplifies the approach of some precedents, such as the Argus and CoastSnap systems, to remotely monitor tidal inundation on a sandy beach at Magilligan on the north coast of Northern Ireland. Such a system could prove essential in the study of the effect of waves and tides on groundwater flow and saline intrusion in coastal aquifers, its consequences for sensitive subsurface infrastructure (such as water supply wells), and in the reconciliation of continuous data from same. Photographic data in this study have been gathered using a remote, solar powered time-lapse camera over a six-month period, capturing full neap and spring tidal cycles. Images are captured at hourly intervals and automatically uploaded to the cloud for remote access. The camera is located just 25 metres from the high water mark, overlooking the beach and perpendicular to the sea. This setup contrasts with previous studies where there is a need to find an elevated location at greater distance from the area of investigation. The extent to which a tide inundates up a sandy beach is governed primarily by astronomical effects, which are considered in this study, but also beach slope and atmospheric conditions. It is known that the beach at Magilligan has both a shallow grade (0.02 m) and a high tidal variation (> 150 m between spring and neap tides). Profiles of beach slope are gathered using a differential GPS, while a solar weather station on site, which also uploads data to the cloud, is used to gather atmospheric data. For tidal reference, a traditional tide gauge measuring tide levels at a pier 15 km east of the site is used. Captured images are post-processed using image analysis techniques based around characterising the tidal front against the visual contrast between pixels of sand and pixels of seawater using a routine in MATLAB</span><span><sup>®</sup></span><span>. From this analysis, a numerical value for tidal inundation is extracted. Analysis of these data indicates that the tide times (timing of high and low tides) correspond well with those measured at the nearby tide gauge, however important differences exist in terms of magnitude. In comparing these differences with atmospheric data from the site, it is possible to align larger and smaller inundation events with shifts in wind direction and speed. The calibration process involved in digitising the captured images is time-consuming, however, it may be possible to predict tidal inundation from a site using only a remote weather station — knowing how a change in wind speed or direction will affect inundation on the beach. It has already been shown that such instrumentation can be used to detect changes in beach morphology (as a key element in tidal inundation), this research therefore represents an important development in the low-cost remote monitoring of tidal inundation, particularly in locations where regular ground surveying is challenging. </span></p>

Snow depth time series retrieval by time-lapse photography: Finnish and Italian case studies

The capability of time-lapse photography to retrieve snow depth time series was tested. Historically, snow depth has been measured manually by rulers, with a temporal resolution of once per day, and it is a time-consuming activity. In the last few decades, ultrasonic and/or optical sensors have been developed to obtain automatic and regular measurements with higher temporal resolution and accuracy. The Finnish Meteorological Institute Image Processing Toolbox (FMIPROT) has been used to retrieve the snow depth time series from camera images of a snow stake on the ground by implementing an algorithm based on the brightness difference and contour detection. Three case studies have been illustrated to highlight potentialities and pitfalls of time-lapse photography in retrieving the snow depth time series: Sodankylä peatland, a boreal forested site in Finland, and Gressoney-La-Trinité Dejola and Careser Dam, two alpine sites in Italy. This study presents new possibilities and advantages in the retrieval of snow depth in general and snow depth time series specifically, which can be summarized as follows: (1) high temporal resolution – hourly or sub-hourly time series, depending on the camera's scan rate; (2) high accuracy levels – comparable to the most common method (manual measurements); (3) reliability and visual identification of errors or misclassifications; (4) low-cost solution; and (5) remote sensing technique – can be easily extended in remote and dangerous areas. The proper geometrical configuration between camera and stake, highlighting the main characteristics which each single component must have, has been proposed. Root mean square errors (RMSEs) and Nash–Sutcliffe efficiencies (NSEs) were calculated for all three case studies comparing with estimates from both the FMIPROT and visual inspection of images directly. The NSE values were 0.917, 0.963 and 0.916, while RMSEs were 0.039, 0.052 and 0.108 m for Sodankylä, Gressoney and Careser, respectively. In terms of accuracy, the Sodankylä case study gave better results. The worst performances occurred at Careser Dam located at 2600 m a.s.l., where extreme weather conditions and a low temporal resolution of the camera occur, strongly affecting the clarity of the images.

Homing behaviour by destructive crown-of-thorns starfish is triggered by local availability of coral prey

Corallivorous crown-of-thorns starfishes ( Acanthaster spp.) can decimate coral assemblages on Indo-Pacific coral reefs during population outbreaks. While initial drivers of population irruptions leading to outbreaks remain largely unknown, subsequent dispersal of outbreaks appears coincident with depletion of coral prey. Here, we used in situ time-lapse photography to characterize movement of the Pacific crown-of-thorns starfish ( Acanthaster cf. solaris ) in the northern and southern Great Barrier Reef in 2015, during the fourth recorded population outbreak of the starfish, but prior to widespread coral bleaching. Daily tracking of 58 individuals over a total of 1117 h revealed all starfish to move a minimum of 0.52 m, with around half of all tracked starfish showing negligible daily displacement (less than 1 m day −1 ), ranging up to a maximum of 19 m day −1 . Movement was primarily nocturnal and daily displacement varied spatially with variation in local availability of Acropora spp., which is the preferred coral prey. Two distinct behavioural modes emerged: (i) homing movement, whereby tracked paths (as tested against a random-walk-model) involved short displacement distances following distinct ‘outward' movement to Acropora prey (typically displaying ‘feeding scars') and ‘homebound' movement to nearby shelter; versus (ii) roaming movement, whereby individuals showed directional movement beyond initial tracking positions without return. Logistic modelling revealed more than half of all tracked starfish demonstrated homing when local abundance (percentage cover) of preferred Acropora coral prey was greater than 33%. Our results reveal facultative homing by Acanthaster with the prey-dependent behavioural switch to roaming forays providing a mechanism explaining localized aggregations and diffusion of these population irruptions as prey is locally depleted.

Buoyant calving and ice-contact lake evolution at Pasterze Glacier (Austria) in the period 1998–2019

Rapid growth of proglacial lakes in the current warming climate can pose significant outburst flood hazards, increase rates of ice mass loss, and alter the dynamic state of glaciers. We studied the nature and rate of proglacial lake evolution at Pasterze Glacier (Austria) in the period 1998–2019 using different remote sensing (photogrammetry, laserscanning) and fieldwork-based (GPS, time-lapse photography, geoelectrical resistivity tomography/ERT, and bathymetry) data. Glacier thinning below the spillway level and glacier recession caused flooding of the glacier, initially forming a glacier-lateral to supraglacial lake with subaerial and subaquatic debris-covered dead-ice bodies. The observed lake size increase in 1998–2019 followed an exponential curve (1998: 1900 m2; 2019: 304,000 m2). ERT data from 2015 to 2019 revealed widespread existence of massive dead-ice bodies exceeding 25 m in thickness near the lake shore. Several large-scale and rapidly occurring buoyant calving events were detected in the 48 m deep basin by time-lapse photography, indicating that buoyant calving is a crucial process for fast lake expansion. We identified a sequence of processes: glacier recession into a basin and glacier thinning below spillway-level; glacio-fluvial sedimentation in the glacial-proglacial transition zone covering dead ice; initial formation and accelerating enlargement of a glacier-lateral to supraglacial lake by ablation of glacier ice and debris-covered dead ice forming thermokarst features; increase in hydrostatic disequilibrium leading to destabilization of ice at the lake bottom or at the near-shore causing fracturing, tilting, disintegration or emergence of new icebergs due to buoyant calving; and gradual melting of icebergs along with iceberg capsizing events. We conclude that buoyant calving, previously not reported from the European Alps, might play an important role at alpine glaciers in the future as many glaciers are expected to recede into valley or cirque overdeepenings.