Mark Gall


Job title and place of work

Scientist. Marine Biogeochemist. NIWA, Wellington.

What is your role in the CARIM project? What work package are you contributing to?

RA3 – I am involved in the design, sampling and analysis of large scale mesocosm experiments (4,000 L test tubes) to determine the effects of temperature and pH on natural planktonic (free floating micro-organisms) populations. In particular, I manage the implementation of a novel experimental system called the Mesocosm Automated Flow Through System (MAFTS). MAFTS pumps water 24/7 through several instruments and is used to track hourly changes over the duration of the experiment [nutrients – nitrate, optical properties of the water (beam attenuation), salinity, temperature, pH, oxygen, turbidity, coloured dissolved organic matter, chlorophyll, and phytoplankton photosynthetic characteristic]. Each mesocosm also has light sensors deployed top and bottom to monitor changes in sunlight, sediment traps to assess material falling out of the water column, and strips to monitor growth on the inside of each bag.

What do you do on an average work day?

I bike to work, recover, then juggle the backlog of data to be analysed and processed in cunning and mysterious ways. This typically involves using a statistical and graphically programming language called ‘R’ (or sometimes Rrrrrrrrrrrrrrrrrrrrrr!). The challenge is to masticate data into a palatable form that is easy to analyse and plot effectively for scientific endeavours.  I specialise in optical water quality (water colour and clarity - aquatic optics, ocean colour) and the link to the water column components (phytoplankton, suspended sediment, coloured dissolved organic matter).

Why is studying coastal acidification important?

Man, impact, consequences! One consequence is a predicted increase in ocean acidification due to rising atmospheric carbon dioxide levels dissolving into the water. The coastal ocean is a crucial and sensitive habitat of high ecological and resource value, and we are uncertain of responses to ocean acidification. Researching the effects of coastal acidification on sensitive organisms (micro- and macro-scopic) will assist in assessing impacts and improving knowledge for future planning and mitigation options. 

What study did you do at high school? And after high school?

I was mainly interested in sciences and technical drawing at school. I was initially unsure what I wanted to do in my first year at Massey University (Biotechnology, Biochemistry, Physiology?) and kept my options open. I ended up completing a BSc and MSc in Biochemistry. My MSc involved using ‘pigs’ as a model for humans, researching the digestion and physiological effects of heated foods. This is a bit different from how my science career has ended up in more liquid environs! 

What outcomes from CARIM do you think there will be?

Improve and communicate knowledge in ecosystem resilience to higher temperature and lower pH conditions. In particular how does the planktonic (phytoplankton and zooplankton) community respond, and what might be the food chain consequences of this. This will help guide implications on future resource management.

What excites you about working on this project?

New knowledge and experience. Being part of an inter-disciplinary team and approach to real-world problems. Science is always challenging, particularly with the integration of technology to environmental monitoring. New methods, techniques and instruments are constantly evolving, allowing monitoring in unprecedented detail in space and time. The CARIM mesocosm experiments provide the opportunity to implement new methods and track changes in time under tightly controlled conditions, something that is difficult (or nearly impossible) in its natural, spatially variable state.