The ecology of Egeria densa Planchón (Liliopsida: Alismatales): A wetland ecosystem engineer?

Abstract

Egeria densa Planchon is considered an invasive species in continental aquatic systems in Chile. Its original geographical distribution was limited to the subtropical regions of Brazil, Argentina and Uruguay. Its fast growth and dense canopy-forming habit are associated with the clear water state of shallow water continental ecosystems. As a dominant species in many of the systems in which it occurs, E. densa behaves as an ecosystem engineer by preventing the re-suspension of sediments and controlling the growth of phytoplankton by removing nutrients from the water column. At the same time, this invasive species produces unwanted effects such as: (1) clogging waterways and hydroelectric turbines, (2) out-competing native vegetation, and (3) negatively affecting the sediment seed bank. Given its importance in the recent (2004) change of state of the Río Cruces wetland, Chile, we felt it appropriate to undertake a comprehensive literature review of this species. We conclude by discussing the role of E. densa as an ecosystem engineer while cautioning against the impression that E. densa is always a highly competitive invader.Key words: Egeria densa, ecosystem engineer, invasive species. RESUMENEgeria densa Planchon es considerada una especie invasora en los sistemas acuáticos de Chile. Su distribución geográfica original estaba limitada a regiones subtropicales de Brasil, Argentina y Uruguay. Su crecimiento rápido y su tendencia a formar densas coberturas suelen estar asociadas con el estado de aguas claras en ecosistemas acuáticos continentales de aguas someras. Su dominancia sugiere que E. densa puede comportarse como una especie ingeniera, previniendo la resuspensión de sedimentos y controlando el crecimiento del fitoplancton a través de la utilización de los nutrientes. Sin embargo, al mismo tiempo, como especie invasora produce efectos no deseados tales como: (1) no permitir el crecimiento de otras macrófitas nativas, (2) disminuir la diversidad en el banco de semillas, y (3) interferir con la navegación y generación de electricidad por turbina. Dada su importancia en el reciente (2004) cambio de estado del humedal del Río Cruces, nos ha parecido oportuno realizar una recopilación de artículos científicos disponibles en la literatura sobre esta macrófita. Concluimos con una discusión sobre el rol de E. densa como especie ingeniera; a la vez que indicamos que la especie tiene ciertas vulnerabilidades y que no cumple siempre con la idea que es una especie invasora muy competitiva.Palabras clave: Egeria densa, especie ingeniera, especie invasora.

A Satellite-Based Assessment of the Distribution and Biomass of Submerged Aquatic Vegetation in the Optically Shallow Basin of Lake Biwa

“…In order to assess the SAV classification accuracy for the other images (i.e., 2013, 2015, and 2016), we identified total 17 SAV stations used for validation (i.e., Station 1,5,6,9,15,18,27,34,36,38,41,42,43,45,48, 49 and 52) out of 52 observation points (Figure 1) based on the available data in Table 1 and the in situ survey (2016). We also used the SAV biomass maps available in the literature for the south basin of Lake Biwa, primarily for the SAV growth period (i.e., mainly September) in 2002, 2007, 2012, and 2014 [63,65].…”

A Conceptual Model of the Aquatic Food Web of the Upper San Francisco Estuary

“…(Jacoby et al 2000;Lehman et al 2005Lehman et al , 2008 and the establishment of nuisance aquatic vegetation (largely E. densa and Eichhornia crassipes) (Brown and Michniuk 2007;Sousa et al 2009Sousa et al , 2010Yarrow et al 2009). Stands of E. densa alter the physical structure of Delta channels and support the colonization of non-native fishes such as sunfish (Centrarchidae), which are often able to outcompete or prey upon native fishes (See 2.30 Structure, below) Grimaldo et al 2004;Nobriga et al 2005;Nobriga and Feyrer 2007;Ferrari et al 2014).…”

Limnological variables and nutritional content of submerged aquatic macrophytes in a tropical lagoon

“…in the rainy period) associated with chlorophyll-a high values (between 10.2 and 64.7 µg.L ), suggesting that this genus had been negatively affected by factors such as higher salt concentration mainly, higher total alkalinity values (<2.8 mEq.L -1 ). Yarrow et al (2009) describe E. densa as highly adaptable, being found throughout the world, except Antarctica, in a wide variety of physic-chemical sub-aquatic environments. Hauenstein and Ramírez (1986) found that E. densa tolerated salinities up to 5, growing naturally in the Valdivia river basin, but in laboratory salinity greater than 1 showed a slight inhibition of photosynthesis, growth and adventitious root production.…”