De Mesel, I.

Moens, T.

Vincx, M.

Open Marine Archive

The influence of nematode diversity on the decomposition of organic matter 
and on the associated bacterial community: an experimental approach 
De Mesel I., T. Moens, and M. Vincx 
Ghent University, Biology Department, Marine Biology Section 
K.L. Ledeganckstraat 35, B-9000 Gent, Belgium 
E-mail : Ilse.DeMesel@rug.ac.be 
The last few years, biodiversity is a hot topic in biological research. Most studies concentrate on 
describing and comparing diversity in different (micro)habitats. Only few studies have examined the role 
of biodiversity, i.e. the relationship between diversity and process rates. 
This project aims to characterise the role of free-living nematodes in the decomposition of plant-derived 
particulate detritus in a brackish saltmarsh. Nematodes are the dominant metazoan group in saltmarshes 
and are characterized by a high species diversity. A stimulatory effect of nematodes as a group or of 
single nematode species on decomposition is known, but this proiect focuses on the relationship between 
nematode species diversity and decomposition rate. 
Most nematodes associated with cordgrass (Spartina townsendii) belong to the same trophic guild 
('deposit feeders') and bacteria are representing their main food source. Because of their seemingly low 
functional diversity, these nematode communities are ideal for the study of species redundancy in 
ecosystems. The central hypothesis in this project is that nematodes will affect the decomposition process 
of Spartina-detritus, but that this will be independent of species identity or diversity; in other words, 
nematodes in this decomposition system have a single 'function' that can be maintained by a single 
- a - "  - 
species, others thus being redundant. 
In order to test this hypothesis, laboratory incubations of Spartina-detritus with and without nematodes 
have been performed. A total of seventeen treatments were kept under controlled abiotic conditions for 
100 days: 4 single species additions, 6 two-species combinations, 4 three-species combinations, one 
four-species combination, one five-species combination and one controle treatment without nematodes. 
Samples were taken every 10 days. In every sample the nematode community, the bacterial community 
and the decomposition will be analysed. 
Nematodes are being counted and biomasses calculated. The decomposition process will be followed by 
measurements of weight loss, C/N/P-content and protein content of the organic matter. Bacterial activity 
is represented by respiration rates, enzyme activity and ATP-measurement. The composition and diversity 
of the bacterial community will be revealed by the molecular technique DGGE (Denaturing Gradient Gel 
Electrophoresis). 
Future experiments will consist of supplementary laboratory experiments and in situ incubations using 
litter bags. 


The influence of nematode diversity on the decomposition of organic matter and on the associated microbial community: an experimental approach

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