The invertebrate colonization during decomposition of Eichhornia azurea kunth in a lateral lake in the mouth zone of Paranapanema River into Jurumirim Reservoir (São Paulo, Brazil)

Abstract

The invertebrate colonization during decomposition of Eichhornia azurea was observed in a lateral lake in the mouth zone of Paranapanema River into Jurumirim Reservoir in two periods of the year. The litter bags method was used for measuring the decomposition rate as well as to evaluate the invertebrates colonization. Forty-two litter bags, measuring 15 × 20 cm in size and 2 mm mesh net, were incubated "in situ". Six litter bags (three for colonization and three for decomposition measurements) were removed after the 1 st , 3 rd , 7 th , 14 th , 28 th , 56 th and 72 nd days of incubation. After each day, the material was carefully cleaned for detritus removal and invertebrate sampling. The biological material was fixed with 4% formaline and then sorted and identified. The remaining plant material was dried in an oven (at 60 o C) and weighed. A fast material loss occurred during the first 24 hours and the decomposition rate was higher during the rainy season than in the dry season. A peak on invertebrate density (110 ind.g.DW -1 ) on the remaining detritus of Eichhornia azurea was recorded in the 56 th day of dry season, when the polyphenol concentration of plant detritus was 0.57 UDO.g.DW -1 . In the rainy season, higher density was found in the 28 th day of incubation, when the polyphenol concentration was 4.36 UDO.g.DW -1 . Apparently, the reduction in the polyphenol concentration was followed by an increase in invertebrate densities. The majority of the species observed in the detritus belongs to the collector group that was dominant after the 7 th and 14 th days in the rainy and dry seasons, respectively.Key words: decomposition, colonization, invertebrate, Eichhornia azurea, lake. RESUMO Decomposição de Eichhornia azurea e colonização por invertebradosA colonização por invertebrados durante o processo de decomposição de Eichhornia azurea foi examinada em duas épocas do ano na zona de desembocadura do Rio Paranapanema,

Colonization by oligochaetes (Annelida: Clitellata) in decomposing leaves ofEichhornia azurea(SW.) Kunth (Pontederiaceae) in a neotropical lentic system

“…The breakdown coefficient of E. azurea leaves found in the present study (k = 0.018 d x1 ) was higher than the values reported for this species in other studies of Brazilian lentic systems: Roland et al (1990) in the Inferna˜o Lagoon (k = 0.011 d x1 ); Pagioro and Thomaz (1998) in the Garc¸as Lagoon (k = 0.0048 d x1 ); Stripari and Henry (2002) in a marginal lake of the Paranapanema River (dry season: k = 0.014 d x1 ; rainy season: k = 0.018 d x1 ). Differences in leaf decomposition rates of the same species can be attributed to different environmental conditions (Schulze and Walker, 1997), such as water temperature, electrical conductivity and dissolved oxygen.…”

Chironomidae larvae associated with Eichhornia azurea leaf detritus: decomposition community structure and colonization dynamics

“…Herbivory in aquatic macroinvertebrates and its effects on the macrophyte biomass are well documented (Lodge 1991;Nachtrieb et al 2011). The biomass of fungus associated with E. azurea leaf detritus had the greatest number of positive correlations with Chironomidae genera in this study, which affirms that the degradation of plant organic matter leads to a reduction of the polyphenol content and the simultaneous colonization by bacteria and fungi, which in turn improves the palatability and nutritional value of detritus (Newman 1991;Stripari and Henry 2002).…”

Structure and density population of the invasive mollusc Limnoperna fortunei associated with Eichhornia crassipes in lakes of the Middle Paraná floodplain

“…Bodamer and Ostrofsky (2010) found that juvenile D. polymorpha leave their attachment to Nuphar stems as a consequence of a deterioration of substrate quality to the mussel. There are some studies about the decomposition of Eichhornia that point out a high loss of allelochemicals (polyphenols) which can benefit or harm the surrounding organisms (Roland et al, 1990;Stripari and Henry, 2002). However, this has not yet been studied with L. fortunei.…”