Read about our great community theatre, Theatre Antigonish (and even read one of my scripts.)

A Look Back

As I begin to wind down my time at StFX, let me take a moment to reflect on some of the high points of my teaching and research career.

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Thomas MacLellan, from Halifax, Nova Scotia, spent two summers exploring the effect of catchment liming on streams and ponds in a tributary basin (Barren Brook) to the St. Mary's River in Guysborough County. His work complemented experiments by Ryan Small (see below), who evaluated conditions before lime was applied. Thomas assessed whether the increase in pH that followed application of lime by helicopter over key areas of the drainage basin led to changes in invertebrate communities and litter decomposition, a key ecological process. He found no difference in streams but a small, temporary increase in litter decay rates in ponds. Thomas’s work is relevant to evaluating both the practice of catchment liming to reverse acidification, and the use of litter decomposition as an environmental indicator.

Evelyn Pequenera-Griffen, from Huntsville, Ontario, managed preliminary laboratory experiments on food-finding behaviour of a large, litter-feeding caddisfly, Pycnopsyche guttifer, which has recently become abundant in local streams. Evelyn tested the hypothesis that larvae sometimes abandon suitable patches of food (leaf litter) in the prospect of randomly finding better ones. Evelyn designed and set up a recirculating laboratory stream to observe how individual larvae respond when presented with two food patches of differing quality. Unfortunately, the life cycle of P. guttifer deprived us of larvae before Evelyn's experiments could produce firm results.

Melissa Pacheco, from Machala, Ecuador, an Honours student in the BASc program in Climate and Environment, spent a summer researching food choices by a large, litter-feeding caddisfly, Pycnopsyche guttifer in South River. Work by previous students in my laboratory showed how an irruption of these historically rare insect larvae led to dramatic increases in leaf litter decay rates. Melissa conducted a set of field experiments to see whether P. guttifer chose food at random or preferred particular litter types. Her experiments confirmed that the larval preferences (alder>maple>aspen>oak) exactly match the fungal abundance and decomposition rates of leaves from these species.

Since graduating in 2022, Melissa has been working in the Department of Earth Science and Environment here at StFX.

Ryan Small, from St. John, New Brunswick, completed his Honours Biology project studying the effect of catchment liming on aquatic ecosystems in Guysborough County. Lime dropped from helicopters onto the forest helps combat the effects of historical acid rain. Ryan monitored temperature and pH in streams and ponds before liming, and followed the progress of leaf litter decomposition to see how ecosystem processes would respond to the lime additions. Ryan's data suggest that decomposers and steam invertebrates are sensitive to pH, so a measurable response to liming is likely to occur.

Ryan took some time off to teach in Spain and travel. He is now pursuing a Master's degree in environmental science and social justice.

Jaclyn Porter, from Saskatoon, Saskatchewan, is a graduate of the Interdisciplinary Studies in Aquatic Resources program at StFX. Her Senior Project concerned the unexpected appearance of a large, voracious leaf-shredding insect, Pycnopsyche guttifer, in streams around Antigonish. These previously rare caddisfly larvae dramatically increase the rate of litter decomposition, much like Lepidostoma togatum (see Erin Wilson, below). Working in the aptly named Porter River, Jaclyn studied how the larvae find food, how quickly they consume it, and which kind of litter they prefer. The irruption of these two leaf-shredding species in reginal streams suggests that a profound reshaping of stream communities is underway.   Abstract

Jaclyn is now pursuing an M.Sc. degree at the University of Saskatchewan.

Jayden Marion was another student in the Interdisciplinary Studies in Aquatic Resources program at StFX. Jayden spent two summers examining aquatic hyphomycete fungi colonizing decomposing leaf litter. He compared community structure inferred from DNA sequencing against the traditional taxonomy based on distinctive spore shapes of each species. He also examined how communities of fungi decomposing leaf litter varied among litter types, streams and seasons. Jayden's work contributes to our understanding of fungal community ecology while also advancing laboratory methods for DNA extraction.    Abstract

Marion is now a Marine Spatial Planning Liaison Officer for the Confederacy of Mainland Mi'kmaq.

Theora Holden, from here in Antigonish (picture at right is the Irish vocalist Enya), completed her Honours Biology project on the distribution of the rare floodplain plant Triosteum aurantiacum (Coffee-weed). Theora surveyed the floodplain forests of four river systems in Antigonish County, using GIS-based predictive maps to greatly expand our records of where the plant occurs. She used PAM fluorometry to determine whether plants were stressed in suboptimal habitat, and used camera traps to establish that seeds are probably distributed by white-tail deer, not birds as previously thought. Theora's work is relevant not only to conservation of this and related rare species, but also contributes to our understanding of rarity generally.    Abstract

Erin Wilson, from Ottawa, Ontario, a recent graduate of the Interdisciplinary Studies in Aquatic Resources program, spent her summer (and autumn!) studying how leaf litter decomposition in regional rivers and streams is influenced by leaf-feeding insects.   Erin's experiments demonstrated remarkable acceleration of leaf decay by larvae of the caddisfly Lepidostoma togatum, which congregate by the dozens on leaf litter in the spring.  These experiments demonstrate unusual dominance of a key ecosystem process by a single species (a "keystone shredder") and suggest severe resource scarcity for aquatic organisms in the highly disturbed rivers of Nova Scotia.    Abstract

Erin has now earned a Master's in Enviromental Management from Dalhousie University.

Gabrielle MacLaughlin, shown here standing by the Cabot Trail, completed a Directed Studies project looking for caddisflies and mayflies in ponds under winter ice. Recent work with Randy Lauff, has revealed a surprising diversity of insects and other organisms active under ice in Nova Scotia ponds. Gabrielle used a variety of novel sampling approaches, including underwater video, to identify and quantify the sub-ice organisms, especially the grazing caddisfly Platycentropus radiatus, and explore their distribution in the ponds. Her work revealed that insects are active and abundant under ice, and may even reside on the under-ice surface. 

Gabrielle completed an M.Sc. degree on cryptic diversity of European bees at the University of Neuchâtel, Switzerland.

Mallory MacDonnell, from Dartmouth, Nova Scotia, a student in the Interdisciplinary Studies in Aquatic Resources program, spent the summer after her junior year helping catch predacious diving beetles (Dytiscidae) in a joint project with Randy Lauff.  These large, predatory beetles are common in ponds and wetlands but their variety and distribution in Nova Scotia are poorly known.  She also tested a novel method of capturing beetles and other aquatic insects using minnow traps baited with light sticks.  Mallory spent many evenings canoeing about in local wetlands, setting traps, and many mornings emptying them.    Abstract

Mallory has since completed an M.Sc. project on spruce budworm at University of New Brunswick.

I am on the cusp of retirement now, so I am no longer taking on new students.