Till startsida

Jon Havenhand - Professor in Marine Ecology

Jon Havenhand researches the evolutionary ecology of reproduction in marine invertebrates, focussing on intra-specific variation in fertilization and larval viability and the role of ocean acidification.

Description of research activities

Ongoing research projects

Scientific publications

Curriculum vitae


Description of research activities

Jon Havenhand’s research focuses on the evolution of early life-history characteristics in marine invertebrates. This ranges from investigations of gamete-compatibilties in broadcast-spawning species, to the selective benefits of different larval forms.

Fertilization and Larval Ecology of marine invertebrates

The majority of marine animals release their gametes freely into the water-column, where they fertilize, and develop. This process is neither Photo: Jon Havenhand. Egg and sperm of the tunicate Ascidia mentula. Broadcast spawning of gametes into the water column is common in marine invertebrates.  Much of Jon Havenhand’s work focuses on the selective pressures that have shaped gamete activation, admixing and fertilization.simple nor risk-free: gametes can face many difficulties locating each other and fertilizing successfully. Gamete dilution can be a big problem, but sometimes eggs may also be exposed to too many sperm - leading to death of the embryo. Once gametes have encountered each other successfully, a variety of compatibility mechanisms may determine which individual’s sperm is most likely to bind, penetrate, and fertilize the egg. Not surprisingly, a variety of adaptations have evolved in response to these selective pressures, and much recent theory has focussed on this.

Fertilized embryos also face a number of challenges - not least because they’re usually unprotected and easy prey for many planktivorous predators. In some species embryos may develop rapdily without feeding into larvae that settle and metamorphose within hours of fertilization. In others, embryos develop as longer-term larvae that feed and grow in the plankton for many weeks before settling to the seabed and metamorphosing into a juvenile.

The great variety of larval forms in marine invertebrates was comprehensively classified only 60 years ago by Gunnar Thorson. Since that time the ecology and evolution of reproduction in marine invertebrates has been a focus of research, not least because the different energetic costs, survival probabilities, dispersal capacities and behaviours of these different larval forms have deep significance for population dynamics, gene-flow, and adaptation in marine species. Jon currently works with several closely related aspects of this area:

  • patterns, causes and consequences of variation in sperm:egg compatibility
  • effects of ocean acidification on early life-history stages of marine invertebrates - including the assessment of non-significant results
  • impacts of larval type on the energetics of adult populations

Jon is pursuing these research interests in collaboration with a number of Masters and PhD students as well as several leading international researchers.

Ongoing research projects

Patterns, causes and consequences of variation in sperm:egg compatibility

This project started several years ago when Jon was working at Flinders University in South Australia. Megan Vandepeer, one of Jon’s graduate students investigated fertilization success in Pacific oysters and showed substantial intra-specific variability in fertilization success. Meegan found that fully reciprocal crosses revealed high (> 70%) individual fertilization success with at least one partner, but that many male x female combinations had relatively low fertilization success. Further development of this work showed similar patterns in a wide variety of different species (molluscs, polychaetes, echinoderms, tunicates), and indications that some of this variability may be under balancing selection.

Subsequent work showed that tunicate sperm were activated - and attracted - by chemical cues from the eggs, and that these cues were to some extent species-specific. Sperm that had not been activated by exposure to the chemical cues could still be viable for more than 12 h in seawater (Bolton & Havenhand 1996). This is considerably longer than had previously been assumed, and has potentially far-reaching consequences for fertilization success in these species. Further work in collaboration with Troy Jantzen (graduate student) and Rocky deNys (James Cook University, Australia) showed that the “halo” of chemical attractant produced by the eggs could extend a significant distance around the egg, even in turbulent conditions, resulting in the prediction that chemical (rather than physical) egg size might determine Photo: Jon Havenhand. Dr Craig Styan, a long-term collaborator and visiting researcher from Australia, analyzing sperm motility of the tunicate Ciona intestinalis in the Motion Analysis Laboratory at Tjärnö.marine invertebrates (Jantzen et al 2001).

Developing theory on the evolution of sexual conflict provided a context for these findings. A collaboration with Craig Styan (Univ. Sydney, Australia) and Lena Kupriyanova (Univ. Adelaide, Australia) tested these ideas by investigating variability in fertilization success between populations of intertidal polychaete in Australia. The resulting incompatibilities between populations from different coasts could not be explained by sexual conflict theory, but were perhaps more related to mechanisms to reduce polyspermy. This work is continuing in collaboration with Craig, and Jane Williamson (Macquarie University).

Effects of Ocean Acidification on early life-history stages of marine invertebrates

Although the world’s oceans contain an enormous amount of water (there are some small planets that weigh less than the volume of the oceans!) increasing levels of CO2 in the atmosphere have caused the surface waters of the ocean to become more acidic. This process, a natural - and very well understood - consequence of rising atmospheric CO2 is referred to as When exposed to acidified seawater (pH 7.7) sperm of the sea urchin Heliocidaris erythro-gramma swam more slowly (red bar) and had lower % motility (orange bar) than in control seawater (pH 8.1).  Modeling the effects of these changes on fertilization predicted a reduction of 25% in fertilization success.  This was remarkably similar to observed reductions of 21% and 26% in experimental treatments (blue bars; Havenhand et al 2008, Current Biology 18: R651-R652).“Ocean Acidification”. Since the onset of the industrial revolution, the acidity of the oceans has increased by about 30% (equivalent to an ≈ 0.1 pH unit fall), and predictions for the year 2100 suggest that continued reliance on burning fossil fuels will cause the oceans to become ≤ 3x more acidic (a pH drop of 0.3-0.4 units).[see http://www.ocean-acidification.net for more details].

For the last several years Jon has been working in collaboration with several researchers, including Mike Thorndyke, Sam Dupont, Elin Renborg, and Anna-Lisa Wrange in CeMEB, to investigate the impacts of Ocean Acidification on the early life-history stages of marine invertebrates. At the Tjärnö laboratory, where Jon is based, the work is focussing on fertilization success and the effects of ocean acidification in combination with other environmental stressors on embryos and larvae.
The first results of this work showed that ocean acidification caused significant reductions in sperm swimming - and hence fertilization success - of an Australian sea urchin (Havenhand, Buttler, Thorndyke & Williamson 2008 Curr.Biol. 18:R651-R652; see Figure). This initial research, done in collaboration with Dr Jane Williamson at Macquarie University, Sydney, Australia, has built into a larger collaboration with Prof. Ove Hoegh-Guldberg’s group at the University of Queensland, Australia, to investigate the impacts of ocean acidification on fertilization and larval development in a range of species on the Australian east coast.
Jon’s research group has continued to investigate these processes in blue mussels, seastars, and oysters in Swedish waters and found varying degrees of susceptibility to ocean acidification see eg Havenhand & Schlegel 2008). This work is continuing in collaboration with Elin Renborg, a PhD student within CeMEB, funded by the EU-BONUS project “Ecosupport”. Intriguingly, intra-specific variation in susceptibility of fertilization success and early larval development can bPhoto Jon Havenhand. Anna-Lisa Wrange in the Sven-Lovén Ocean Acidification facility - Tjärnö with her experiment investigating the effects of ocean acidification and salinity on barnacle larvae.e substantial in some species. This latter aspect is the focus of a collaboration with Jane Williamson, Dr Haruko Kurihara, Univ. Nagasaki, Japan and Dr Laura Parker, Univ. W. Sydney, Australia, investigating the effects of ocean acidification on populations of the Pacific oyster Crassostrea gigas from around the world.

Salinity has a marked effect on the effects of atmospheric CO2 on ocean pH: more saline waters are better able to buffer the effects of CO2. [NB this property is actually a function of the total alkalinity of the seawater AT, which is correlated with salinity]. Consequently, increases in atmospheric CO2 will have greater impact on pH in low salinity waters than on the open ocean, and this can be seen from the greater pH variation observed in low-salinity Baltic waters in comparison to the higher salinity Skagerrak, for example. Investigating the adaptational and evolutionary consequences of his is a core aspect of several research projects running within CeMEB, not least among which is the effect of salinity and acidification on the larval stages of the barnacle Amphibalanus improvisus. PhD student Anna-Lisa Wrange is investigating gene-expression and larval settlement in barnacle larvae exposed to these treatments.

Assessing non-significant results from experiments

Designing experiments so that we can maximize our power to infer from the results is a key aspect of any field of science. In Ocean Acidification research this is particularly important because considerable reliance is being placed on an (as yet) small data set. Bringing key concepts of experimental design and analysis to the field has been the focus of a strategic collaboration between Jon, Gerry Quinn (Deakin University, Australia) and Sam Dupont. Together, these researchers have contributed a chapter on experimental design and analysis for the EPOCA Guide to Best Practice in Ocean Acidification Research.

It is often as important to know when a given experiment or treatment has not had an impact as it is to know when it has. Unfortunately, experiments may yield non-significant results for two reasons: i) there was no biological effect of the treatments, or ii) the design of the experiment was not adequate to detect an effect. Distinguishing between these two is not difficult, however many authors fail to do so, preferring instead to conclude that non-significant results are evidence of “no effect”. This is simply wrong - statistically non-significant results are non-conclusive (a principle that was established almost a century ago: Fisher RA 1935 The design of experiments. Hafner, New York).

Some authors have recommended the use of “Power Analysis” to address this issue, however this approach is potentially fatally flawed, and alternative methods that assess confidence intervals around effect size are recommended (see eg Havenhand, Dupont & Quinn (in press) and Nakagawa & Foster 2004 Acta Ethologica).

Impacts of larval type on the energetics of adult populations

Photo Jon Havenhand. A newly hatched veliger larva of the gastropod Bembicium nanum.  The maternal energy invested in each larva is a primary determinant of reproductive success.






Participation in EU-Networks

  • European Project on Ocean Acidification (EPOCA)
Advanced tool for scenarios of the Baltic Sea ECOsystem to SUPPORT decision making (ECOSUPPORT)
  • WreckProtect



Scientific publications

Jon Havenhand has published more than 50 scientific publications including several edited book chapters. The publications have been cited more than 600 times. (H-index = 17.)

Full list of publications as pdf-file

Key publications:

Serrão, EA & JN Havenhand (2009) Fertilization strategies In: M.Wahl (ed) Marine Hard Bottom Communities. Springer, Heidelberg. p 149-164.

Havenhand, JN & Schlegel, P., 2009. Near-future levels of ocean acidification do not affect sperm motility and fertilization kinetics in the oyster Crassostrea gigas. Biogeosciences, 6, 3009-3015.

Dupont, S., J.N. Havenhand, W. Thorndyke, L. Peck, M.C. Thorndyke (2008) CO2-driven ocean acidification radically affects larval survival and development. Marine Ecology Progress Series. 373: 285-294

Johannesson K, Havenhand JN, Jonsson PR, Lindegarth M, Sundin A, Hollander J (2008) Male discrimination of female mucous trails permits assortative mating in a marine snail species. Evolution 62: 3178-3184

Havenhand JN, Buttler F-R, Thorndyke MC, Williamson JE (2008) Near-future levels of ocean acidification reduce fertilization success in a sea urchin. Current Biology 18: R651-R652

Styan, C.A, E. Kupriyanova, J.N. Havenhand (2008) Strong barriers to cross-fertilization between populations of a polychaete species are unlikely to have arisen through gametic compatibility arms-races. Evolution. 62: 3041-3055

Bolton, T.F. & J.N. Havenhand (2005) Physiological acclimation to decreased water temperatures and the relative importance of water viscosity in determining the feeding performance of larvae of a serpulid polychaete. Journal of Plankton Research. 27: 875-879

Gamfeldt, L., J. Wallén, P.R. Jonsson, K.M. Berntsson, J.N. Havenhand (2005) Increasing intraspecific diversity enhances settling success in a marine invertebrate. Ecology. 86: 3219-3244

Hanlon, R.T., M. Naud, P.W. Shaw & J.N. Havenhand (2005) Transient sexual mimicry leads to fertilization. Nature 433: 212-212.

Naud, M., P.W. Shaw, R.T. Hanlon, & J.N. Havenhand (2005) Evidence for biased use of sperm sources in female giant cuttlefish (Sepia apama). Proceedings of the Royal Society of London, Series B. 272: 1047-1051.

Naud, M., R.T. Hanlon, K.C. Hall, P.W.Shaw & J.N. Havenhand (2004) Behavioral and genetic assessment of mating success in a natural spawning aggregation of the giant cuttlefish (Sepia apama) in southern Australia. Animal Behaviour 67: 1043-1050

Kupriyanova, E & J.N. Havenhand (2002) Variation in sperm swimming behaviour and its effect on fertilization success in the serpulid polychaete Galeolaria caespitosa Invert. Repr. & Devt. 41: 21-26.

Jantzen, T.M., R. de Nys, & J.N. Havenhand (2001) Fertilization success and the effects of sperm chemoattractants on effective egg size in marine invertebrates. Mar Biol.138: 1153-1161.

Havenhand, J.N. (1995) Evolutionary ecology of larval types. In: L.R. McEdward (ed.) Ecology of Marine Invertebrate Larvae, CRC Press, N.Y. p. 79-122

Havenhand, J.N. (1993) Egg to juvenile period, generation time, and the evolution of larval type in marine invertebrates. Mar. Ecol. Prog. Ser. 97: 247-260

Curriculum vitae

Curriculum vitae for Jon Havenhand

Contact information

Jon Havenhand

University of Gothenburg

Department of Biological and Environmental Sciences

University of Gothenburg





CeMEB - The Linnaeus Centre for Marine Evolutionary Biology


+46 (0)31 786 96 82



Grafic fish for CeMEB


The Linnaeus Centre for Marine Evolutionary Biology -CeMEB

To the top

© University of Gothenburg, Sweden, Box 100, S-405 30 Gothenburg
Phone +46 31-786 0000, Contact

About the website | Map