Environmental variables, pesticide pollution and meiofaunal community structure in two contrasting temporarily open/closed false bay estuaries

Environmental variables (including natural and anthropogenic stressors) and meiobenthic communities were sampled in a ‘natural’ (Rooiels) and a ‘disturbed’ (Lourens) estuary in the Western Cape, South Africa, bimonthly for 20 months. A primary aim of the study was to assess if the meiobenthic community structure is driven by different variables when comparing ‘natural’ versus ‘disturbed’ system. Due to the much smaller catchment of the Rooiels Estuary, many environmental variables were significantly different (p<0.001) from the variables in the Lourens Estuary, e.g. salinity, temperature, pH, total suspended solids, nitrate and depth. No pesticide concentrations were expected in the Rooiels Estuary due to the absence of agricultural development in the catchment. However, chlorpyrifos (8.9 µg/kg), prothiofos (22.0 µg/kg) and cypermethrin concentrations (0.42 µg/kg) were detected frequently, with the highest concentrations recorded during the summer months. Principal response curve analysis showed that temporal variability between sampling dates explained 42% of the variance in environmental variables and pesticide concentrations and spatial variability between the 2 estuaries explained 58%. Variables contributing most to the differences were higher concentrations of endosulfan, p,p-DDE and nitrate concentrations in the Lourens Estuary and larger grain size and higher salinity at the bottom in the Rooiels Estuary. In general the meiofaunal community in the Rooiels Estuary showed a significantly higher number of taxa (p<0.001), a significantly higher Shannon Wiener Diversity Index (

A Vision for Transdisciplinarity in Future Earth: Perspectives from Young Researchers

Meeting the demand for food, energy, and water as world population increases is a major goal for the food systems of the future. These future challenges, which are complex, multiscalar, and cross-sectoral in nature, require a food systems approach that recognizes the socio-ecological and socio-technical dimensions of food (Ericksen, 2008; Ingram, 2011; Rivera-Ferre, 2012). The United Nations' Future Earth Program aims to provide a new platform for consolidating the knowledge required for societies to transition to global sustainability (Future Earth Transition Team, 2012). In this paper, we explore how Future Earth could become a vehicle for inspiring the production of new research ideas and collaborations for sustainably transforming the future food system. We do this on the basis of a synthesis of views from 28 young (below 40 years old) food system scientists, representing five continents. Their expertise comes from disciplines including food engineering, agronomy, ecology, geography, psychology, public health, food politics, nutritional science, political science, sociology and sustainability science. This paper begins with an outline of the institutional framework of Future Earth and how it might support innovative transdisciplinary research on food systems, and the position of young scientists within this framework. Secondly, we outline the key insights expressed by the young scientists during the Food Futures Conference in Villa Vigoni, Italy, in April 2013, including the core research questions raised during the meeting as well as some of the challenges involved in realizing their research ambitions within their professional spheres

Environmental variables, pesticide pollution and meiofaunal community structure in two contrasting temporarily open/closed false bay estuaries

Environmental variables (including natural and anthropogenic stressors) and meiobenthic communities were sampled in a ‘natural’ (Rooiels) and a ‘disturbed’ (Lourens) estuary in the Western Cape, South Africa, bimonthly for 20 months. A primary aim of the study was to assess if the meiobenthic community structure is driven by different variables when comparing ‘natural’ versus ‘disturbed’ system. Due to the much smaller catchment of the Rooiels Estuary, many environmental variables were significantly different (p<0.001) from the variables in the Lourens Estuary, e.g. salinity, temperature, pH, total suspended solids, nitrate and depth. No pesticide concentrations were expected in the Rooiels Estuary due to the absence of agricultural development in the catchment. However, chlorpyrifos (8.9 µg/kg), prothiofos (22.0 µg/kg) and cypermethrin concentrations (0.42 µg/kg) were detected frequently, with the highest concentrations recorded during the summer months. Principal response curve analysis showed that temporal variability between sampling dates explained 42% of the variance in environmental variables and pesticide concentrations and spatial variability between the 2 estuaries explained 58%. Variables contributing most to the differences were higher concentrations of endosulfan, p,p-DDE and nitrate concentrations in the Lourens Estuary and larger grain size and higher salinity at the bottom in the Rooiels Estuary. In general the meiofaunal community in the Rooiels Estuary showed a significantly higher number of taxa (p<0.001), a significantly higher Shannon Wiener Diversity Index (

Spatial and temporal variability in particle-bound pesticide exposure and their effects on benthic community structure in a temporarily open estuary

Spatial and temporal variations in particle-bound pesticide contamination, natural environmental variables, and benthic abundance were measured during the dry summer season within a temporarily open estuary (Lourens River). This study focused on the effect of particle-associated pesticides on the dynamics of the benthic community (including epi-benthic, hyper-benthic, and demersal organisms) by comparing two runoff events, differing in their change in pesticide concentration and environmental variables. The two chosen sites were situated within the upper and middle reaches of the estuary and differ significantly in salinity (p = 0.001), flow (p = 0.5), temperature (p <0.001) and particulate organic carbon in the sediment (p <0.001). Generally higher particle-bound pesticides were found in the upper reaches. The first runoff event was characterised by an increase in pesticides (chlorpyrifos, endosulfan and cypermethrin) and hardly any change in natural environmental variables, whereas the second runoff event was characterised by no increase in pesticide but a significant change in natural environmental variables like salinity, temperature and flow. The most evident spatial difference in community structure was shown by the use of Principal Response Curve after the first runoff event, whereas no response was shown after the second runoff event. The variables which explained most of the spatial differences are Total Organic Carbon, salinity, chlorpyrifos and endosulfan concentrations. The species contributing most to the spatial differences are the estuarine harpacticoid Mesochra and Canthocamptus (lower abundance at the upper reaches) and the freshwater species Dunhevedia and Thermocyclops (higher abundance within upper reaches). Within the spatial variability (between upper and middle reaches) the authors were able to detect a link between endosulfan, chlorpyrifos exposure, TOC and salinity and community change by comparing the two runoff event

Spatial and temporal variability in particle-bound pesticide exposure and their effects on benthic community structure in a temporarily open estuary

Spatial and temporal variations in particle-bound pesticide contamination, natural environmental variables, and benthic abundance were measured during the dry summer season within a temporarily open estuary (Lourens River). This study focused on the effect of particle-associated pesticides on the dynamics of the benthic community (including epi-benthic, hyper-benthic, and demersal organisms) by comparing two runoff events, differing in their change in pesticide concentration and environmental variables. The two chosen sites were situated within the upper and middle reaches of the estuary and differ significantly in salinity (p = 0.001), flow (p = 0.5), temperature (p <0.001) and particulate organic carbon in the sediment (p <0.001). Generally higher particle-bound pesticides were found in the upper reaches. The first runoff event was characterised by an increase in pesticides (chlorpyrifos, endosulfan and cypermethrin) and hardly any change in natural environmental variables, whereas the second runoff event was characterised by no increase in pesticide but a significant change in natural environmental variables like salinity, temperature and flow. The most evident spatial difference in community structure was shown by the use of Principal Response Curve after the first runoff event, whereas no response was shown after the second runoff event. The variables which explained most of the spatial differences are Total Organic Carbon, salinity, chlorpyrifos and endosulfan concentrations. The species contributing most to the spatial differences are the estuarine harpacticoid Mesochra and Canthocamptus (lower abundance at the upper reaches) and the freshwater species Dunhevedia and Thermocyclops (higher abundance within upper reaches). Within the spatial variability (between upper and middle reaches) the authors were able to detect a link between endosulfan, chlorpyrifos exposure, TOC and salinity and community change by comparing the two runoff event