Biogeochemical response of an intact coastal sediment to organic matter input: a multivariate approach

Abstract

We tested the effect of additions of organic matter of different quality (C:N ratio) and quantity on benthic fluxes of ammonium, nitrate, silicate, oxygen and dissolved inorganic carbon (DIC). Additions were made to intact sediment boxes, according to a 2-level factorial design, and the magnitude and temporal scale of the response were evaluated with Partial Least Square (PLS) regression analysis. Response patterns were followed over a 40 d period following the addition, but only fluxes of ammonium, nitrate, silicate and oxygen for the first 2 d after addition, and nitrate fluxes for the first 8 d after addition, could be used for predictive modelling. The results showed that the response of the microbial community to different qualities and quantities of organic matter may initially be related to its capacity to sequester organic matter, and in the long term, to its growth in response to the respective nutritional supply. The results also suggest that such an experimental approach can be a useful tool for classification of areas with potential risk of eutrophication.

Partial least squares regression as an alternative to current regression methods used in ecology

“…Recent examples of the use of PLSR can be found in some areas of ecology, such as microbial ecology (Stepanauskas et al 2003, Allen et al 2005), paleolimnology (Zhang et al 2007), limnology (Larocque et al 2006, Karle et al 2007, Sobek et al 2007), soil ecology (Ekblad et al 2005), ecotoxicology (Sonesten 2003, Spanos et al 2008), environmental effects on biodiversity (Maestre 2004, Davis et al 2007, Palomino and Carrascal 2007), palaeoclimatological reconstructions and biogeography (Seppa et al 2004), large scale influence of climate (Bergant et al 2006, Finsinger et al 2007), biodiversity mapping (Schmidtlein 2005), definition of ecological indicators (Amand et al 2004, Potapova et al 2004), community ecology (ter Braak and Schaffers 2004, Carrascal and Alonso 2006), modelling of phenology (Gordo et al 2008) and ecomorphology (Hoffsten 2004). Results of Zhang‐yu et al (2007) also demonstrate that PLSR is more effective than stepwise MR or regression analyses with PCA in relating hyperspectral leaf reflectance in rice Oryza sativa crops to the disease severity of the fungus Bipolaris oryzae .…”

Sulfur, carbon, and nitrogen cycling in faunated marine sediments impacted by repeated organic enrichment

“…In these studies, the entire sediment matrix has usually been uniformly enriched (Kristensen & Hansen 1995, Sloth et al 1995, Hansen & Kristensen 1998, Banta et al 1999 or OM was added as a single pulse to the sediment surface (Sloth et al 1995, Pedersen et al 1999, Kristensen & Mikkelsen 2003, Papaspyrou et al 2004, Karle et al 2007. Although these studies have provided knowledge on the general impacts of organic enrichment, they cannot simulate the behavior of e.g.…”

Metabolic threshold and sulfide-buffering in diffusion controlled marine sediments impacted by continuous organic enrichment

“…The effects of OM-enrichment on sediment biogeochemistry have mostly been studied in closed sediment incubations (Holmer and Kristensen 1994a, b;Kristensen and Hansen 1995) or in plug incubations open to an overlying water reservoir (Kristensen and Hansen 1995;Sloth et al 1995;Banta et al 1999;Papaspyrou et al 2004;Karle et al 2007). These batch studies have provided valuable basic knowledge on the impact of organic enrichment on sediment metabolism.…”