Marine Biology @ UKZN

Contact

Room 030, George Campbell Building, Howard College campus

Tel: +27 31 260 7410

Fax: +27 31 260 2029

E-Mail: smitaj(at)ukzn.ac.za

Qualifications

B.Sc. (University of Port Elizabeth)

B.Sc. Hons. (University of Port Elizabeth)

M.Sc. (University of Port Elizabeth)

Ph.D (University of Cape Town)

Modules taught

BIOL101W1 — Smaller Side of Life

BIOL342W1 — Marine Ecophysiology  

BIOL231W2 — Marine Environment

BIOL341W2 — Marine Systems

BIOL784HC — Marine Ecosystem Analysis  

Research Interests

The effect of DMSP in integrated algal-abalone cultivation systems

Algal cultivation

DMSP reportedly functions as anti-oxidant in algae, and its production is mediated by environmentally induced stress that impairs algal photosynthetic performance. We aim to study these stressors in Ulva and Gracilaria cultivation systems and in kelp beds in order to understand algal DMSP production. We plan to evaluate the anti-oxidant role of DMSP through assessing chlorophyll fluorescence. This information will be used to select and produce feeds with an optimal DMSP content that will ensure the production of high-quality abalone meat. We will also validate reports of growth-promoting properties of DMSP in invertebrates, and study other physiological functions of the compound on the physiology of the abalone. This research involves collaboration with the CSIR, various abalone farms, Prof. Richard Hill at Michigan State University, and researchers at the University of Cape Town.

A Micro-PIXE study of DMSP in abalone

A map of S distribution in the epipodial frill of abalone produced by micro-PIXE (M. Desai).

The proposed work will focus on the most likely scenario for DMSP elimination from abalone body tissue: loss via the excretory organs, gills or across the tissue-water interface. Micro-PIXE (Proton-Induced X-ray Emmision spectroscopy) will be used to map the spatial distribution of DMSP in and around these sites by using sulphur concentration as a proxy for DMSP. This study runs in collaboration with Drs Jolanta Mesjasz-Przybylowicz and Wojciech Przybylowicz at iThemba Labs in Somersetwest near Cape Town.

Marine benthic ecology

Sampling kelp in Cape Town

Stable isotope ecology

The measurement of natural abundance stable isotope signals in various ecosystem components provides a powerfully incisive means for identifying sources of natural or anthropogenic carbon (C) or nitrogen (N) entering an ecosystem, for studying its assimilation and transformation by photoautotrophs at the base of a trophic structure, and for following subsequent incorporation and transport through the food web. In some situations, it offers the only feasible tool for studying subtle changes in marine communities resulting from human impacts, but wherever possible it should be used in conjunction with other complementary forms of measurement and acquiring data. One of my main interests is the application of stable isotope measurements to problems related to marine ecosystems in order to better understand their structure and processes. Currently we have such a project in the Greater St. Lucia Wetland Park. Experimental investigations of isotopic fractionation

A hypothetical food web

Meta-analysis of stable isotope data

Stable isotopes of carbon, nitrogen, and sulphur are widely used in ecological studies. The measurement of these ratios in the biota is used for the identification of sources of natural or anthropogenic minerals that enter an ecosystem and which are transformed via several processes as it passes through organisms in the food web. A central premise that underpins our ability to make accurate ecological predictions from stable isotope data is that the degree to which the relative ratio of the heavy to the light isotope changes as it moves from food to consumer organisms is constant and predictable. This change is usually associated with C, N, and/or S flows (because of feeding) from one trophic position to the next and is termed the isotopic fractionation factor, ?δ13C, ?δ15N or ?δ34S (here simply denoted as ?). Nevertheless, a careful survey of the literature reveals that ? ranges widely. Is this due to random error or because of overlooked predictable influences remains uncertain?

We find that a deviation from the assumed constant ? of +1 per mil and +3 to +4 per mil associated with 13C/12C and 15N/14N transfer, respectively, may be underpinned by physiological causes which may be classified into A) variations in tissue specific turnover rates (metabolic and because of isotopic dilution during growth), and B) variations in the consumer-diet isotopic discrimination. Very few studies (with notable exceptions) have attempted to systematically synthesise these findings into a framework that could be applied to isotope studies, thereby reducing or explaining some of the uncertainties surrounding the description of trophic interactions. Uncertainties stemming from the lack of information in ? affect our ability to interpret the data and come to reliable conclusions.

The following broad questions concerning variations in ? are therefore posed, and form the basis of this research proposal: i) Will a more detailed understanding of variations in isotopic turnover rates among animals improve the certainty with which ? can be known? ii) Will knowing the factors controlling the consumer-diet isotopic fractionation among animals improve the certainty of which ? can be known? In the process of answering these questions, large volumes of data will become available which can be used to synthesise ecological theory from the individual studies surveyed. Therefore, iii) can we generalise ecological theory from individual stable isotope ecology studies?

All questions will be addressed by implementing detailed meta-analyses (quantitative literature review), but an experimental approach will be used to address specific hypotheses for which there is a paucity of data.

Environmental impacts of marine pollution

Eutrophication is one of the biggest impacts on coastal marine ecosystems today. It is difficult to generalise about the effects of nutrient enrichment on the environment as it depends largely on where the impact occurs, but in a broad sense it is safe to say that the main effect is on the primary producers. Understanding sources of nutrients entering coastal water bodies via catchments has important implications for management of our natural resources. For this reason I am very interested in the biological (physiological and ecophysiological) effects of nutrient enrichment on algae, and consequent effects on other trophic levels. Particulate matter in riverine discharge is another type of pollution with potentially significant effects (increased sedimentation and turbidity) on marine ecosystems. Since some reefs along the KwaZulu-Natal coastline is susceptible to this type of impact, this research direction will also be a fruitful line of enquiry. There are many 'tools' available for studying marine pollution of which the application of stable isotopes of N and C is one of the most powerful. This work complements my interest in nutrient flow pathways discussed earlier. I am involved in a project with the CSIR that looks at marine pollutants along the KZN coastline.

The biology of commercially important macroalgal species

Kelp and sea urchins, Cape Town

Recent Publications

• Anderson RJ, Bolton JJ, Smit AJ, Gillespie R, Rotmann KWG, Critchley AT (2006) The Seaweed Resources of South Africa. In: Seaweed Resources 1.0 (Critchley AT, Ohno M, Largo D, eds.), ETI BioInformatics, The Netherlands.
• Botes L, Smit AJ, Cook PA (2003) The potential threat of algal blooms to the abalone (Haliotis midae) mariculture industry situated around the South African coast. Harmful Algal Blooms 2: 247-259.
• Gartner A, Lavery P, Smit AJ (2002) Using the ?15N values of different functional forms of macroalgae and filter-feeders to reveal temporal and spatial patterns in sewage distribution. Marine Ecology Progress Series 235: 63-73.
• Rothmann MD, Anderson RJ, Smit AJ (2006) The effect of kelp (Ecklonia maxima) harvesting on kelp population structure, growth rate and recruitment in South Africa. Journal of Aplied Phycology DOI: 10.1007/s10811-006-9036-8.
  
• Smit AJ (2001) Source identification in marine ecosystems: food web studies using ?13C and ?15N. In: (Unkovich MJ, Pate JS, McNeil AM, Gibbs J, eds.), Stable Isotope Techniques in the Study of Biological Processes and Functioning of Ecosystems, Kluwer Academic Publishers.
• Smit AJ (2004) Medical and pharmaceutical applications of seaweed natural products. A review. Journal of Applied Phycology 16: 245-262.
• Smit AJ (2006) Bioactivity and pharmacology of seaweed natural products. In: Seaweed Resources 1.0 (Critchley AT, Ohno M, Largo D, eds.), ETI BioInformatics, The Netherlands.
• Smit AJ, Brearley A, Hyndes GA, Lavery PS, Walker DI (2006) ?15N and ?13C analysis of a Posidonia sinuosa seagrass bed in Western Australia. Aquatic Botany 84: 277-282
• Smit AJ, Brearley A, Hyndes GA, Lavery PS, Walker DI (2005) Carbon and nitrogen stable isotope analysis of an Amphibolis griffithii seagrass bed. Estuarine, Coastal and Shelf Science 65: 545-556
• Smit AJ, Fourie AM, Robertson BL, du Preez DR (2003) Control of the herbivorous isopod, Paridotea reticulata, in tank cultures of Gracilaria gracilis. Aquaculture 217: 385-393
• Vanderklift MA, Kendrick GA, Smit AJ (2006) Differences in trophic position among sympatric sea urchin species. Estuarine, Coastal and Shelf Science 66: 291-29

Links

General biology links

• Darwin Online

Marine biology links

• World Ocean Observatory - Ocean Forum
• Marine Biology
• ReefVid: A resource of free coral reef video clips for educational use

Marine data links

• The NOAA National Oceanographic Data Center

Advice on presentations

• Advice on designing scientific posters
• Scientifically Speaking

R graphics and statistical analysis

• Gallery of R graphics
• R Wiki
• R graphical manual