Associate Professor Marc Schallenberg

Contact

Email marc.schallenberg@otago.ac.nz

Research Interests

I grew up in Canada and, after a false start studying to be a medical doctor, I did a PhD in Limnology at McGill University in Montreal.

In 1994, I arrived in New Zealand to take up a postdoc with the National Institute of Water and Atmospheric Research in Christchurch and a year later I carried on my lake research career at the University of Otago, working with Professor (now Emerita Professor and Dame) Carolyn Burns.

In my more than 30 years of working on New Zealand’s lakes, ponds, wetlands, and lagoons, I have had over 100 study sites from Northland to Campbell Island, as well as in Antarctica. I’m interested in a wide range of scientific approaches including empirical (field-based) and experimental studies, as well as inferential research (e.g., palaeolimnology) and modelling (statistical and deterministic). I have an extensive network of collaborators and have mentored (supervised) over 20 graduate students through their dissertations. I’ve been the president of the New Zealand Freshwater Sciences Society and have been advising Central Government and Regional Councils on freshwater science and policy for over 20 years. There is a great demand for scientific advice to support monitoring and restoration. I undertake pro bono work with a number of lake care, land care, and citizen science groups as well as with schools in Otago and Southland.

I am always looking for keen and capable graduate students with a focus on pretty much any aspect of freshwater science. I always have a few ideas for research projects, whether they be for Honours, Masters, or PhD students (see below for some examples).

Past and current projects

My past and current projects tend to fall into the following general areas:

• Anthropogenic impacts on lake ecosystems (mainly eutrophication but also other contaminants and climate change)
• How environmental gradients structure freshwater communities, including keystone and indicator species
• Microbial carbon, nitrogen, phosphorus, and oxygen cycling
• Inferring past lake conditions from the study of sediment archives (palaeolimnology)

Current pet research themes

• Drivers of mucilage production by freshwater diatoms (“lake snow”)
• Food webs and energy flow in deep, pre-alpine lakes (e.g., Lakes Wakatipu, Wanaka, Hawea)
• Quantification of microbial nutrient cycling
• Operationalising stressor-response relationships for management and restoration

Current and Recent Postgraduate Students

As main supervisor

• Ashimi Dilhara (PhD current) Ecosystem function and species response in intermittently closed estuaries: Integrating hydrology, nutrient dynamics, and organic matter quality
• George Brookland (PGDipSci current) Analysis of the relationship of waterfowl abundance, land use and water quality of intermittently closed estuaries
• Helen Trotter (MSc 2022) Potential use of biomanipulation to improve water quality in a eutrophic Central Otago lake
• Sami Khan (PhD 2021) Pelagic food web resilience and potential of biomanipulation techniques to help restore ecological integrity in two eutrophic lakes in New Zealand
• Amy Weaver (PhD 2016) Low-intensity land use in grassland catchments: Effects on a large, oligotrophic lake
• Tina Bayer (PhD 2013) Effects of climate change on two large, deep oligotrophic lakes in New Zealand

As co-supervisor

• Grace Fortune-Kelly (PhD current) Fish communities in lakes on Rēkohu/Chatham Islands
• Fasil Teddese Wolebu (PhD 2019) Fish assemblages and life history patterns in estuaries along the Otago coastline, New Zealand

Potential areas for Postgraduate Research

Any topics mentioned above plus research areas below that I am currently exploring:

• Non-determinism in complex systems: New approaches to modelling emergent phenomena in lakes (e.g., algal blooms, mucilage events, trophic cascades, outcomes of species invasions, etc.)
• Enhancement of nutrient acquisition via chitin microfibrils production by the nuisance freshwater diatoms, Didymosphenia geminata and Lindavia intermedia
• Nitrogen fixation in lake snow: Can the nuisance pelagic diatom, Lindavia intermedia, fix atmospheric nitrogen?
• Here to stay: Accounting for ecosystem services provided by invasive species
• Marine subsidies: How much did seabirds and sea lions elevate the productivity of coastal lakes and wetlands in pre-human times?
• Dead zones: Linking terrestrial carbon inputs to anoxic bottom waters in lakes
• The importance of silicon (re)cycling in lakes dominated by diatoms
• Holistic thinking: Using Bayesian causal inference for environmental decision making

Marc's Up-to-date publications and citations via Google Scholar