Nutrients, carbon and productivity Outcomes summary Concentrations of nutrients, carbon and chlorophyll-a as well as of Gross Primary Production (GPP) and Ecosystem Respiration (ER) are key covariates that account for variability in primary producers (e.g. photosynthetic algae and plants) and dependent higher-trophic indicator organisms such as invertebrates and fish (). Flow plays a critical role in supporting ecosystem metabolic processes both in rivers and wetlands. Samples of nutrients, carbon and chlorophyll-a were collected fortnightly between October 2014 and January 2015 at six sites across the Narrandera and Carrathool zones of the Murrumbidgee River. While in wetlands, concentrations of nutrients, Dissolved Organic Carbon (DOC) and chlorophyll-a were sampled every 2 months across ten sites between September 2014 and March 2015. Relevant objectives relating to environmental water delivery to the Lowbidgee Floodplain (Action 6) include the provision of habitat to support the survival and maintain condition of native fish, waterbirds, and other aquatic vertebrates. In there were no environmental watering actions specifically targeting in-channel or wetland nutrients, carbon and chlorophyll-a and rates of GPP and ER. However, environmental water deliveries to the Lowbidgee floodplain contributed to patterns of in-channel hydrological variability, providing baseline information to help explain the potential role of environmental flows in maintaining ecological beneficial concentrations of nutrients, carbon and chlorophyll-a and rates of GPP or ER. Key findings There were two notable peaks in nutrient levels which coincided with increasing water levels in the Murrumbidgee River. This was explained by increasing water levels during bulk water deliveries which resulted in the inundation of dry sediments and the release of nutrients.
Nutrients, carbon and productivity Outcomes summary Concentrations of nutrients, carbon and chlorophyll-a as well as of Gross Primary Production (GPP) and Ecosystem Respiration (ER) are key covariates that account for variability in primary producers (e.g. photosynthetic algae and plants) and dependent higher-trophic indicator organisms such as invertebrates and fish (). Flow plays a critical role in supporting ecosystem metabolic processes both in rivers and wetlands. Samples of nutrients, carbon and chlorophyll-a were collected fortnightly between October 2014 and January 2015 at six sites across the Narrandera and Carrathool zones of the Murrumbidgee River. While in wetlands, concentrations of nutrients, Dissolved Organic Carbon (DOC) and chlorophyll-a were sampled every 2 months across ten sites between September 2014 and March 2015. Relevant objectives relating to environmental water delivery to the Lowbidgee Floodplain (Action 6) include the provision of habitat to support the survival and maintain condition of native fish, waterbirds, and other aquatic vertebrates. In there were no environmental watering actions specifically targeting in-channel or wetland nutrients, carbon and chlorophyll-a and rates of GPP and ER. However, environmental water deliveries to the Lowbidgee floodplain contributed to patterns of in-channel hydrological variability, providing baseline information to help explain the potential role of environmental flows in maintaining ecological beneficial concentrations of nutrients, carbon and chlorophyll-a and rates of GPP or ER. Key findings There were two notable peaks in nutrient levels which coincided with increasing water levels in the Murrumbidgee River. This was explained by increasing water levels during bulk water deliveries which resulted in the inundation of dry sediments and the release of nutrients.
murumbidgee-ltim-report-technical-appendices.docx