The comb jelly Mnemiopsis leidyi is an invasive comb species which has successfully established itself in European seas. We analyze numerous data on this species eco-physiology to understand how it partitions its energy between essential functions such as maintenance, development, growth and reproduction. This is done with the longer term aim to better understand its dynamics in the field.
This comb jelly is renowned for producing spectacular blooms whereby sampling nets capture mind boggling amounts of these species. In between blooms little or no individuals are found in the water column. We know that this species remains somewhere in the water column from egg to adult: it has no resting or sedentary life-stages. Thus, two very relevant questions are: how does this species persist in between blooms and how can so many individuals appear so rapidly.
We contribute to these two questions in our study by modelling how the metabolism of this species actually responds to environmental changes in food and temperature over its different life-stages. The model is tested for realism by comparing the predictions with many different data sets published as far back as 1974 up to the present.
This is to our knowledge a first modelling attempt to describe the maintenance, development, growth and reproduction of this species with a same model and a same set of parameters. Three main exciting results stem from this exercise.
First, we found that 12 degrees C might already be below this species optimum thermal tolerance range. That means that future studies need be really careful when comparing results across studies performed at different temperatures. We provide concrete improvement for how future studies can temperature correct their data.
Next, we discovered that M. leidyi seems to undergo a so-called metabolic acceleration after hatching. Intriguingly, the onset of the acceleration appears to be delayed and the data do not yet exist which allows determining what actually triggers it. It is hypothesized that this delay confers a lot of metabolic flexibility by controlling generation time.
Last, we compared the DEB model parameters for this species with those of another gelatinous zooplankton species (Pelagia noctiluca). Both species turn out to have very different energy allocation strategies: P. noctiluca has an extremely high reserve capacity, low turnover times of reserve compounds and high resistance to shrinking. M. leidyi adopts the opposite strategy: it has a low reserve capacity, high turnover rates of reserve compounds and fast shrinking.
This last exercise supports the idea that the DEB model parameters for this species actually reflect important eco-physiological properties meaning that if one were to obtain such parameters for many different species within an eco-system then one could reflect on the link between ‘properties’ or ‘traits’ of a species and their function in the system. This information alongside knowledge of which ‘functions’ are relevant for an eco-system would help predict changes in structure and functioning of eco-systems on the basis of changes in distributions of traits.
This study is published in the 2014 special issue on Dynamic Energy Budget theory in the Journal of Sea Research
Information about the Dynamic Energy Budget theory research program and its results can be found at http://www.bio.vu.nl/thb/deb/
Reference:
Augustine, S., Jaspers, C., Kooijman, S. A. L. M., Carlotti, F., Poggiale, J.-C., Freitas, V., van der Veer, H. and van Walraven. L. Mechanisms behind the metabolic flexibility of an invasive comb jelly. (2014) Journal of Sea Research, DOI:10.1016/j.seares.2014.09.005