Variation in predation by soft-bodied predators from the tropics to the poles
Supervisors: Dr David Aldridge (Department of Zoology), Professor Lloyd S Peck, Dr Melody S Clark (British Antarctic Survey), Dr Elizabeth M Harper (Department of Earth Sciences)
Importance of the area of research: There has been a long history, and significant effort over many decades in attempting to understand how predation in the sea varies from region to region (Vermeij 1987, Navarette 1996), with latitude and depth and also in past geological periods. The paradigm is that predation pressure is higher in the tropics than the poles (Aronson et al. 2007, Freestone et al. 2011), and the value of prey to predators compared to effort required to overcome defences, and factors such as effects of prey size on predation have been studied (Peck, 1993, Jablonski et al. 1996, Harper et al. 2009) This work has been almost exclusively restricted to analyses of the impacts of crushing and drilling predators, because evidence of attacks is present on skeletons of their prey. Evaluations of impacts of soft bodied predators, e.g. anemones and engulfing worms is scarce to absent. Here we will quantify levels of soft bodied predation pressure on seabed communities across the globe.
What the project will involve: There are three elements to this work: 1. Using literature sources to obtain estimates of numbers and biomass of soft bodied marine predators at sites spanning all latitudes; 2. Analysing the commonest prey items taken by the most abundant soft-bodied predators at any given site, from the literature, from feeding experiments and from gut content analyses. 3. Making measurements of oxygen consumption and absorption efficiencies for a range of soft-bodied predators. From measures of absorption efficiency (mass/energy of food consumed – mass/energy of faeces produced) and metabolic rates we will calculate the mass of food needed to maintain predator body mass. Combining this with data for predator biomass will allow a minimum amount of prey needed to maintain predator populations. All the above will be assessed for polar, temperate and tropical species. This will allow wide scale patterns across regions to be identified
Aronson, R.B. et al. (2007). Ann. Rev. Ecol. Evol. Syst. 38: 129-154.; Freestone A.L. et al. (2011). Ecology 92: 983-993.; Harper, E.M. et al. (2009). Mar Biol 156: 1993-2000.; Jablonski et al. (1996) Evolutionary paleobiology. Univ Chicago Press; Navarette SA (1996). Ecol Monogr 66:301–321; Peck, L.S. (1993). Phil. Trans. Roy. Soc. Lond. B,. 339: 17-32. Vermeij GJ (1987) Evolution and escalation. Princeton Univ Press.