Autor(es):
Lillebø, Ana Isabel 
; Flindt, Mogens R. ; Pardal, Miguel Ângelo ; Marques, João Carlos
Data: 1999
Identificador Persistente: http://hdl.handle.net/10316/13092
Origem: Estudo Geral - Universidade de Coimbra
Assunto(s): Spartina maritima; Decomposition; Fauna; Nutrient mass balance
Descrição
Decomposition of salt marsh plants results from physical, chemical and biological processes including abiotic and biotic
fragmentation, microbial decay and chemical transformation. According to literature data, only a few species have the ability to feed directly
on living plant material, so fungi and bacteria seem to be the principal competitors for the organic substrates. Nevertheless, by consuming
bacteria, protists and fungi associated to the detritus, macrofauna and meiofauna recycle the incorporated nutrients. Moreover, this nutrient
regeneration may be seen as an effective factor in maintaining and stimulating bacterial production. In fact, it is well known that many detritus
feeding species have very low assimilation efficiencies. The objective of the present study was to compare the nutrient mass balance of carbon;
nitrogen and phosphorus in Spartina maritima covered areas and bare bottom sediment, with and without contribution of macrofauna, meiofauna
and microbial populations. Nutrients mass balance was studied taking into account the initial and final nutrient concentrations in the sediment,
water and plant material. Faunal activity was measured as a function of remineralised carbon, nitrogen and phosphorus. The experimental set-up
included sixteen sub-experiments, which varied with respect to type of fauna, plant biomass and oxic status. Each sub-experiment was
performed in small glass containers (3 L) containing about 900 g wwt sediment and 2.5 L estuarine water. Plant material, cut from intact plants,
sediment cores and estuarine water were brought from the southern arm of the Mondego estuary (Portugal). The results showed that although
the bacterial activity was responsible for the Spartina maritima degradation, the presence of meiofauna and macrofauna significantly enhanced
the process. Moreover, the presence of Spartina maritima positively affected the mineralisation of the sediment carbon and nitrogen, especially
when the three faunal components were present, and denitrification rates were highest in the presence of the macrofauna and meiofauna. The
present study suggests that macrofauna and meiofauna have an important role on the ecosystem nutrient flux and that fauna might function as
a sink for excess nutrients, that otherwise could be exported to the coastal waters http://dx.doi.org/10.1016/S1146-609X(99)00141-1
