GBR-wide Summary 2013 -2014

The 2013-2014 monitoring year was characterised by below average rainfall and discharge of the major rivers of the four NRM regions (Table 7). The ratio of freshwater discharge in 2013-2014 to the long-term median ranged from 0.2 – 3.3 compared to 0.5 – 3.1 in the previous monitoring year (Table 7; Bentley et al, 2012). Notably, only the Daintree River had a ratio of 3.3, whereas all others ranged from 0.2 – 1.3.

Table 7 Comparison of long-term median flows in major rivers with total discharge of 2013-2014

*River discharge data compiled by Michelle Devlin. (Data Source Department of Environment and Resource Management, Stream Gauging Network). Long-term median flow data was provided by Shaffelke et al 2011, and determined from the commencement of river monitoring up to the year 2000. Long-term median water year is from October 1^st to September 30^th the following year.

Overall, the PSII-HEqs of deployed samplers were lower than the previous monitoring year (2012-2013), as periods of high river flow typically coincide with increased PSII-HEq concentrations (see Appendix F, Figures 23 – 27). The PSII herbicides detected at inshore reef locations in the current monitoring year were ametryn, atrazine, bromacil (detected three times only), desethyl atrazine, desisopropyl atrazine, diuron, hexazinone, prometryn (detected once only), simazine and tebuthiuron. The most frequently detected and highest concentration herbicides in this current monitoring year were diuron (maximum concentration of 27 ng L^-1 at Sarina Inlet in the Mackay Whitsunday region), atrazine (maximum concentration of 7 ng L^-1 at Sarina Inlet) and hexazinone (maximum concentration of 12 ng L^-1 at Sarina Inlet). Metolachlor and imidacloprid were also detected frequently although at relatively low concentrations (maximum concentrations of 1.3 and 1.6 ng L^-1 in EDs, respectively). At fixed monitoring sites, no herbicides with an individual Guideline to assess against exceeded its Guideline value (Figure 3).

NRM Region River

Rus s el l -Mul gra ve 1,724,059 2,266,282 1.3

North Johns tone 1,758,717 2,164,524 1.2

23 National Research Centre for Environmental Toxicology

Entox is a joint venture between The University of Queensland and Queensland Health

Diuron was the dominant contributor to the PSII-HEq Max at every fixed monitoring site due to its potency as a PSII inhibitor and its relatively higher concentrations (Figure 3). Diuron contributed an average of 84 % to the PSII-Max in the Wet Tropics (excluding Normanby Island), 82 % in the Burdekin, 84 % in the Mackay Whitsundays (excluding Pioneer Bay) and 97 % at North Keppel Island in the Fitzroy. The contribution of diuron remained relatively consistent between the sites within the Wet Tropics (80 % - 85 %) and Mackay Whitsunday region (81 % - 85 %) but varied more widely within the Burdekin region (72 % at Orpheus Island to 91 % at Magnetic Island).

Figure 3 Maximum concentrations of individual herbicides at fixed monitoring sites from the commencement of sampling to 2013-2014

25 National Research Centre for Environmental Toxicology

Entox is a joint venture between The University of Queensland and Queensland Health

There was a possible decrease in the maximum concentrations of herbicides detected at all sites (with the exception of Low Isles) when compared to the previous monitoring year (Figure 3). The greatest decrease was observed in the Mackay Whitsundays region, with the maximum concentration of diuron decreasing by almost 10 times.

Since monitoring commenced, 73 % of PSII-HEq Max values in the Wet Tropics have been Category 5, and 27% have been Category 4 (Figure 4). As observed in the Wet Tropics, atrazine and diuron concentrations were lower than the previous year, by an average 4.1 and 2.2 times respectively (excluding Low Isles and Normanby Island). The frequency of detection of ametryn, desethyl atrazine and simazine decreased (concentrations remain low) by a factor of 2 or more, when compared to the previous monitoring year (Bentley et al, 2012).

Since monitoring commenced in the Burdekin region, 68 % of PSII-HEq Max values have been Category 5, 28 % of PSII-HEq Max values have been Category 4 on the PSII-HEq Index with a single instance of a Category 3 (Figure 4). Decreases in the maximum concentrations of herbicides were detected at all sites, with the most significant decreases observed at Magnetic Island and Cape Cleveland. Similarly to the Wet Tropics, the abundance of atrazine and diuron decreased when compared to the previous monitoring year by average factors of 12 and 5.8 respectively. For the previous four years, Cape Cleveland has had the highest maximum concentration of herbicides in this region.

Since monitoring commenced, 29 % of PSII-HEq Max values in the Mackay Whitsunday region have been classified as Category 5, 59 % of values have been Category 4 and a further 12 % as either Category 2 or 3 (Figure 4). Sarina Inlet and Outer Whitsunday showed the most significant decrease in PSII-HEq Max values of any site when compared to the previous monitoring year. Despite this decrease, Sarina Inlet remains the most ‘at risk’ site with the most frequent detections of herbicides (atrazine, desethyl atrazine, diuron, hexazinone and tebuthiuron detected in 100 % of samplers) and the highest PSII-HEq Max (34 ng L^-1) of all fixed monitoring sites.

Since monitoring commenced, 78 % of PSII-HEq Max values at North Keppel Island have been Category 5 and 22% have been Category 4 on the PSII-HEq Index (Figure 4). The PSII-HEq Max for this current monitoring year was the lowest of all fixed sites since monitoring commenced. Two deployment periods (November 2013 and March 2014) were found to have no detectable levels of PSII herbicides. Following the spike in tebuthiuron detected in the previous year (57 ng L^-1), concentrations did not exceed 1 ng L^-1 in this current monitoring year.

Figure 4 PSII-HEq Max at each fixed monitoring site since monitoring commenced to 2013-2014

In 2013-2014, the PSII-HEq Max for the regions ranged from 3.3 – 8.5 ng L^-1 in the Wet Tropics (excluding Normanby Island), 2.7 – 8.1 ng L^-1 in the Burdekin Region, 4.9 – 34 ng L^-1 in the Mackay Whitsunday (excluding Pioneer Bay) and was 0.60 ng L^-1 in the Fitzroy region. These values indicate maximum PSII-HEq Index Categories of 5 for the Wet Tropics, Burdekin and Fitzroy regions, and Category 4 and 5 in the Mackay Whitsunday region. The majority of sites in all regions showed a decrease in PSII-HEq Max values compared to the previous monitoring year, with the decrease the most apparent in the Mackay Whitsunday region. Sarina Inlet in the Mackay Whitsunday region, for the fifth consecutive year (since monitoring at Sarina Inlet commenced) had the highest PSII-HEq Max value.