Environmental factors affecting Phragmites australis litter decomposition in Mediterranean and Black Sea transitional waters

Abstract

ABSTRACT1. Leaf litter decomposition rates in aquatic ecosystems are known to be related to many abiotic and biotic factors.2. Field experiments were carried out during spring 2005 in 16 ecosystems, each with four sampling sites, using the litter bag technique to investigate the influence of abiotic factors on patterns of reed litter breakdown in different physiographic, hydrological and physico-chemical gradients occurring in transitional water ecosystems in the Eastern Mediterranean and Black Sea.3. Significant differences in leaf litter decomposition were observed among the studied ecosystems along univariate gradients of tidal range, water temperature, salinity and sinuosity index.4. Overall, 71% of variance in the litter breakdown rate was explained by the hydrological, physico-chemical and physiographic components. Specifically, tidal range, salinity and sinuosity index are among the key factors in the most commonly used typological schemes for classifying transitional water ecosystems (i.e. Confinement Concept and Venice System), due to their influence on abundance and distribution of benthic macroinvertebrates and other guilds.5. The patterns observed at the regional scale of the study suggest that certain key abiotic factors are likely to play a major role as drivers of plant detritus decomposition processes, through their influence on the overall metabolism of microorganisms and benthic macroinvertebrates.

Seasonal and multi-annual patterns ofPhragmites australisdecomposition in a wetland of the Adriatic area (Northeast Italy): a three-years analysis

“…The decomposition rates (k) of Phragmites australis leaf litter determined in the present study (k = 0.0066−0.0075 days −1 in autumn; k = 0.0108−0.0158 days −1 in spring; k = 0.0168 days −1 in summer) for a large temporary pond of the Isonzo River Mouth Reserve are consistent with literature data (Table 4) (Sangiorgio et al, 2008a) and experimental conditions, such as different types of leaf bags mesh size (Bedford, 2005;Quintino et al, 2009). The results of the present work highlight the following points: (i) temporal patterns of reed decomposition were observed, resulting in a clearly defined cycle; (ii) a high percentage of the variability in reed decomposition within the studied pond is explained by rainfall and, to a lesser extent, by water temperature and conductivity.…”

“…Temperature is one of the main driving factors in P. australis breakdown, positively influencing the decay rate values (Hanson et al, 1984;Webster and Benfield, 1986;Bedford, 2005;Sangiorgio et al, 2008a;Eid et al, 2014): water temperature increases microbial processing during decomposition and leaves served as a major energy source for invertebrates in aquatic ecosystems (Dudgeon, 1982); the role of microfungi and invertebrates in decomposition is well-known (Gessner and Chauvet, 1994;Graça, 2001;Hieber and Gessner, 2002;Menéndez et al, 2003).…”

“…In the pond under exam, water conductivity reflects salinity levels which could negatively influence P. australis processing (Mendelsshon et al, 1999;Sangiorgio et al, 2008a) and this effect could likely be mediated by the activity of microorganisms and benthic macroinvertebrates (Quintino et al, 2009). Several studies showed that increasing salinity correspond to decreasing microorganism activity (van Bruggen and Semenov, 2000;Rietz and Haynes, 2003;Sardinha et al, 2003;Muhammad et al, 2006;Wichern et al, 2006).…”

“…Plant breakdown rates in aquatic ecosystems have been found to be affected by internal factors, such as distinctive characteristics of the leaves (Kok et al, 1990;Canhoto and Graça, 1996), and by external environmental factors such as water temperature and salinity (Carpenter and Adams, 1979;Reice and Herbst, 1982;Vought et al, 1998;Sangiorgio et al, 2008a;Quintino et al, 2009), pH (Thompson and Bärlocher, 1989), nutrients (Elwood et al, 1981;Sharma and Gopal, 1982;Sangiorgio et al, 2008b), or regional characteristics (Sangiorgio et al, 2008a), such as climate (Murphy et al, 1998) and solar radiation (Denward and Tranvik, 1998). Litter breakdown has been widely studied in streams and rivers (Graça and Pereira, 1995;Diez et al, 2002;Menéndez et al, 2003;Pinna et al, 2003;Pinna et al, 2004;Sangiorgio et al, 2006), lakes (Gupta et al, 1996;van Dokkum et al, 2002) and transitional aquatic ecosystems, such as coastal lagoons or river mouths (Rossi and Costantini, 2000;Menéndez et al, 2004;Sangiorgio et al, 2004;Bayo et al, 2005;Sangiorgio et al, 2008aSangiorgio et al, , 2008b.…”

“…Litter breakdown has been widely studied in streams and rivers (Graça and Pereira, 1995;Diez et al, 2002;Menéndez et al, 2003;Pinna et al, 2003;Pinna et al, 2004;Sangiorgio et al, 2006), lakes (Gupta et al, 1996;van Dokkum et al, 2002) and transitional aquatic ecosystems, such as coastal lagoons or river mouths (Rossi and Costantini, 2000;Menéndez et al, 2004;Sangiorgio et al, 2004;Bayo et al, 2005;Sangiorgio et al, 2008aSangiorgio et al, , 2008b. Otherwise, the decomposition of biomass on temporary freshwater wet sites with seasonally fluctuating water levels has received relatively little attention (Bedford, 2005;Völlm and Tannenberger, 2014).…”