Self-organization on mudflats

PhD ceremony: Mr. E.O. Folmer, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Self-organization on mudflats

Promotor(s): prof. T. Piersma, prof. H. Olff

Faculty: Mathematics and Natural Sciences

Self-organization – the process of repeated interactions or feedbacks among elements that make up the system resulting in the spontaneous development of an element-transcending, higher level structure or function, without the intervention of an external regulator – underlies various natural phenomena. Eelke Folmer studied two ecological examples: site choice of foraging shorebirds and the development of seagrass meadows.

Folmer investigated the first case by means of simulations and spatial statistical models on the basis of observations in the Wadden Sea. His research confirms the hypothesis that foraging distributions result from the availability of resources and social attraction between individuals. The latter derives from the fact that the presence of conspecifics signals the presence of food and decreases the risk of becoming prey. Another result from his research is the development, testing and application of a method to estimate the level of attraction while accounting for exogenous factors. An important conclusion is that the current distribution models, which are based on competition and exogenous factors only, do not adequately capture foraging behaviour and its spatial distribution.

Folmer investigated the second case on the basis of remote sensing data and local measurements in intertidal seagrass beds in the Banc d’Arguin in Mauretania. This research - in which he applied structural equation models - shows that seagrass controls its own development by means of capturing fine sediments which is detrimental to seagrass density. This system is also characterized by interaction between endogenous and exogenous factors. An important conclusion is that non-recursive structural models, based on cross section data of different development stages, may provide insight into the development of seagrass through time.