Differences in the macrozoobenthic fauna colonising empty bivalve shells before and after invasion by Corbicula fluminea

Bivalve shells can potentially alter the structure of aquatic benthic communities. However, little is known about the effect that different shell morphologies have on their associated fauna. This study aimed to understand how empty shells, from four different freshwater bivalve species, affect macrozoobenthic communities, using the River Minho (Iberian Peninsula) as a study area. Three native (Anodonta anatina, Potomida littoralis, Unio delphinus) and one non-indigenous (Corbicula fluminea) species were used for this research. Comparisons among species and between scenarios (i.e. before and after invasion by C. fluminea) were performed. Our results suggest that macrozoobenthic community structure did not vary among treatments, with the exception of species richness, which was higher on shells of native species. Furthermore, little difference was detected when comparing scenarios with and without C. fluminea shells, despite dissimilarities in size and morphology between species. The empty shells of C. fluminea partially (in terms of density and biomass, but not in species richness) replaced the role of empty shells of native species as a physical substratum for the associated macrozoobenthic community.Martina Ilarri is supported by a Post-doc grant (SFRH/BPD/90088/2012) from the Portuguese Foundation for Science and Technology – FCT through POPH/FSE funds. This study was conducted within the scope of the project ECO-IAS: Ecosystem-level impacts of an invasive alien species, supported by FCT and COMPETE funds (contract: PTDC/AAC-AMB/116685/2010) and was also partially supported by the European Regional Development Fund (ERDF) through COMPETE funds (PEst-C/MAR/LA0015/2011) and by FCT/MEC through Portuguese funds (PIDDAC – PEst-OE/BIA/UI4050/2014).info:eu-repo/semantics/publishedVersio

Distribution of Corbicula fluminea (Müller, 1774) in the invaded range: a geographic approach with notes on species traits variability

Corbicula fluminea is considered one of the most important non-native invasive species (NIS) in aquatic systems mainly due to its widespread distribution and ecological and economic impacts. This species is known to negatively affect native bivalves, also with severe effects on biodiversity and ecosystem functioning. Throughout an exhaustive bibliographic survey and with the aid of Geographic Information Systems tools, this study tracks the species dispersion from its native range, including the description of important physical and environmental barriers. Additional analyses were conducted to examine possible influences of latitudinal/ temperature gradients on important traits (e.g. life span, maximum and mean body length, growth at the end of first year). Altitude and winter minimum temperature appear to be delaying the invasion worldwide, but it seems inevitable that the species will spread across the globe. Latitude and summer temperature show a relationship with growth and life span. Overall, the information gathered in this review may be relevant to forecast future distribution patterns of this NIS, and to anticipate the possible implementation of effective management measures. Moreover, it may constitute a valuabletool inthe prediction of population responses to an increasingly changing environment.This research was supported by FCT (Portuguese Foundation for Science and Technology), through a PhD grant attributed to D. Crespo (SFRH/BD/80252/2011), a post-doc grant attributed to S. Leston (SFRH/BPD/91828/2012) and M Dolbeth (SFRH/BPD/41117/2007) and BIOCHANGED project (PTDC/MAR/111901/2009), subsidized by the European Social Fund and MCTES (Ministério da Ciência, Tecnologia e Ensino Superior) National Funds, through the POPH (Human Potential Operational Programme), QREN (National Strategic Reference Framework) and COMPETE (Programa Operacional Factores de Competitividade).info:eu-repo/semantics/publishedVersio

The role of organisms in hyporheic processes : gaps in current knowledge, needs for future research and applications

Fifty years after the hyporheic zone was first defined (Orghidan, 1959), there are still gaps in the knowledge regarding the role of biodiversity in hyporheic processes. First, some methodological questions remained unanswered regarding the interactions between biodiversity and physical processes, both for the study of habitat characteristics and interactions at different scales. Furthermore, many questions remain to be addressed to help inform our understanding of invertebrate community dynamics, especially regarding the trophic niches of organisms, the functional groups present within sediment, and their temporal changes. Understanding microbial community dynamics would require investigations about their relationship with the physical characteristics of the sediment, their diversity, their relationship with metabolic pathways, their inter- actions with invertebrates, and their response to environmental stress. Another fundamental research question is that of the importance of the hyporheic zone in the global metabolism of the river, which must be explored in relation to organic matter recycling, the effects of disturbances, and the degradation of contaminants. Finally, the application of this knowledge requires the development of methods for the estimation of hydro- logical exchanges, especially for the management of sediment clogging, the optimization of self-purification, and the integration of climate change in environmental policies. The development of descriptors of hyporheic zone health and of new metrology is also crucial to include specific targets in water policies for the long-term management of the system and a clear evaluation of restoration strategies

Life at the extreme: meiofauna from three unexplored lakes in the caldera of the Cerro Azul volcano, Galapagos Islands, Ecuador

Muschiol D, Traunspurger W. Life at the extreme: meiofauna from three unexplored lakes in the caldera of the Cerro Azul volcano, Galapagos Islands, Ecuador. AQUATIC ECOLOGY. 2009;43(2):235-248.On Isla Isabela, Galapagos Archipelago, three so far unexplored lakes were investigated in the caldera of Cerro Azul, one of the most active volcanoes in the world. The lakes face recurrent desiccation and eruption events and showed distinct differences in their water chemistry. Thirty cores from the upper 15 cm of sediment indicate distinct differences in the composition of meiobenthic communities between the lakes. In total, 27 different aquatic metazoan species could be distinguished. Numerically, rotifers dominated in two of the lakes, with mean densities up to 4.56 x 10(6) individuals m(-2) while the third lake was dominated by a gastrotrich of the genus Chaetonotus (0.67 x 10(6) individuals m(-2)). The largest lake harboured up to 14.4 x 10(6) nematodes m(-2), which is the highest nematode density thus far reported for a freshwater habitat. The lakes yielded few nematode species (S = 7, N = 887) and calculation of the Shannon-Wiener index (H') indicated an exceptionally low nematode diversity. The nematode community of one lake was clearly dominated by an undescribed suction-feeding Mesodorylaimus (59.6%), the community of the other lake by the epistrate feeder Achromadora pseudomicoletzkyi (89.3%), whereas the third lake surprisingly contained no nematodes. The benthic nematode biomasses for the two nematode-containing lakes differed by a factor 50. The food webs of the three lakes are presumed to have an exceptionable simply structure

Combined influence of river discharge and wind on littoral nematode communities of a river mouth area of Lake Constance

Witthoeft-Muehlmann A, Traunspurger W, Rothhaupt KO. Combined influence of river discharge and wind on littoral nematode communities of a river mouth area of Lake Constance. AQUATIC ECOLOGY. 2007;41(2):231-242.The littoral nematode community adjacent to a river mouth (River Schussen) on Lake Constance (Germany) was studied from February 1999 to January 2000 in order to determine the influence of stress resulting from fluctuations in river discharge on local nematode assemblages. Additionally, the influence of wind as a second important stress factor was considered. Six sample sites were chosen, reflecting a gradient of river influence within the broader river mouth area. Nematode communities, varying in a mean range from 121 to 165 ind/10 cm(2), were found to differ significantly in terms of abundance, feeding type composition and species diversity. Deposit feeders were most abundant at all sites followed by chewers. Deposit feeders were affected mainly by wind events, while species diversity and the occurrence of chewers were influenced mainly by river discharge. The impact of both these stress factors was modified by a third variable, water level. Moderate and high levels of combined habitat stress led to significant changes in community structure. Under conditions of calm weather and low discharge, reduced species diversity and an increased predominance of deposit feeders were observed. In most cases, species diversity was found to be higher under moderate stress conditions, an observation that offers support for Connel's Intermediate Disturbance Hypothesis