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Wet Tropics summary

The Wet Tropics’ overall inshore marine condition remained poor in 2011-2012 and 2012-2013. Inshore water quality remained poor and seagrass meadows declined from poor in 2010-2011 to very poor in 2011-2012 and 2012-2013. Coral reefs were in poor condition having declined from moderate in 2011.

Wet Tropics marine condition graph

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Wet Tropics snapshot

A standardised scoring system was developed for each of the key indicators in the report card. The scoring system is used to assess and communicate progress towards the management practice and catchment targets as well as current marine condition using the following categories:

Results—colour coding
Very goodGoodModerate
PoorVery Poor 

Management practices

Grazing Sugarcane Horticulture
Proportion of graziers who adopted improved practices between 2009 and 2013.
Target: 50 per cent by 2013
Proportion of growers who adopted improved practices between 2009 and 2013.
Target: 80 per cent by 2013
Proportion of producers who adopted improved practices between 2009 and 2013.
Target: 80 per cent by 2013
Grazing 23% Sugarcane 45% Horticulture 50%

Catchment indicators

Groundcover Nitrogen Sediment Pesticides
Late dry season groundcover as at 2012–2013.
Target: 50 per cent by 2013.
Reduction in annual average total nitrogen load between 2009 and 2013.
Target: 50 per cent
Reduction in annual average sediment load between 2009 and 2013.
Target: 20 per cent by 2020
Reduction in annual average pesticide load between 2009 and 2013.
Target: 50 per cent by 2013
Groundcover 94% Nitrogen 8% Sediment 13% Pesticides 26%

Management practices

Sugarcane

Sugarcane 45% - Moderate resultTarget: 80 per cent by 2013.
From 2009 to 2013, 45 per cent of sugarcane growers (604) are known to have adopted improved land management practices, up from 39 per cent (523) to June 2012.

There are 1,343 growers managing 1,364 square kilometres of land in the Wet Tropics region.

By June 2013, cutting-edge (A) or best management (B) practice systems were used by 61 per cent of sugarcane growers for nutrients, 26 per cent for herbicides and 27 per cent for soil. This was up from 57 per cent for nutrients, 20 per cent for herbicides and 23 per cent for soil in June 2012.

Graph data (.csv, 1KB)

Of the 604 growers who implemented improved practices, 348 completed Reef Rescue Water Quality Grants projects facilitated by Terrain Natural Resource Management, including:

  • 245 growers implemented improved nutrient management practices
  • 218 growers implemented improved herbicide management practices
  • 246 growers implemented improved soil management practices.

Approximately 212 growers were estimated to have progressed from D level nutrient management systems to C level nutrient management systems through a combination of concerted Reef Rescue program extension efforts from a range of sources (Terrain Natural Resource Management, BSES Ltd and local agronomic services providers) and the introduction of the Queensland Government's regulations. A further 44 growers are estimated to have improved management through Queensland Government extension services. The Reef Rescue program improved management practices on over 20,000 hectares of sugarcane farm land in the Wet Tropics region from 2009 to 2013.

Grazing

Grazing 23% -  Poor resultTarget: 50 per cent by 2013.
From 2009 to 2013, 23 per cent of graziers (213) are known to have adopted improved land management practices, up from 19 per cent (176) to June 2012. The grazing industry in the Wet Tropics region has not been a high priority area for Reef Plan due to scale and relatively high year-round groundcover levels.

There are 935 graziers managing 6983 square kilometres of land in the Wet Tropics region.

By June 2013, 77 per cent of graziers were using (A or B) practice systems that are likely to maintain land in good to very good condition or improve land in lesser condition, up from 73 per cent in June 2012.

Graph data (.csv, 1KB)

A total of 187 graziers who implemented improved practices completed Reef Rescue Water Quality Grants projects facilitated by Terrain Natural Resource Management. The Reef Rescue program directly supported a further 25 graziers to complete relevant capacity building through Queensland Government extension services.

Horticulture

Horticulture 50% - Moderate resultTarget: 80 per cent by 2013.
From 2009 to 2013, 50 per cent of horticulture producers (164) are known to have adopted improved land management practices, up from 45 per cent (147) to June 2012.

There are 330 horticulture producers managing 198 square kilometres of land in the Wet Tropics region. Bananas are the dominant sector, with 250 growers accounting for nearly 60 per cent of this total area.

By June 2013, cutting-edge (A) or best management (B) systems were used by 62 per cent of horticulture producers for nutrients, 88 per cent for herbicides and 68 per cent for soil.

All 164 horticulture producers who implemented improved land management practices from 2009 to 2013 did so with the support of Reef Rescue Water Quality Grants, facilitated by Terrain Natural Resource Management and the Growcom Farm Management System (FMS) program. Of these, 94 completed nutrient management projects, three completed herbicide management projects and 94 completed soil management projects.

Graph data (.csv, 1KB)

Industry-wide management system adoption is estimated using the proportions established through the Growcom FMS in each region, and expressed as the percentage of growers with A, B, C or D management systems.

It is important to note that the level of grower participation in the program has increased year by year. As the proportion of the grower population represented in the program increases, so the distribution of A, B, C or D management systems changes over time as a reflection of the larger and more representative sample size. Early participants in the program have often been relatively progressive landholders, and this is apparent in terms of relatively high proportions of A and B in the management system distribution in early years. Increasing program participation over time can have the effect of diluting the percentage of growers in the A and B categories over time. This is not to be seen as a regression of farm management systems.

Catchment indicators

Groundcover

Groundcover 94% - Very good resultTarget: 50 per cent by 2013.
Late dry season mean groundcover for the grazing lands of the Herbert catchment was high (92 per cent by June 2012 and 94 per cent by June 2013). The 26-year mean groundcover was 89 per cent.

Groundcover results for the Herbert catchment (Wet Tropics region)
Catchment/ region 26-year mean groundcover (%) 2012 mean groundcover (%) 2013 mean groundcover (%) Area with less than 50% groundcover averaged over past 26 years (%) Area with less than 50% groundcover in 2012 (%) Area with less than 50% groundcover in 2013 (%)
Herbert (Wet Tropics region) 89 92 94 0.9 0.3 0.2

Groundcover changes over time

The Herbert catchment had consistently high mean groundcover from 1988 to 2013 with a mean groundcover level of 89 per cent and a consistently low proportion of grazing lands under the target of 50 per cent groundcover. The minimum mean groundcover for the monitoring period was 76 per cent in 1988.

Graph data (.csv, 1KB)

The highest percentage of area with groundcover below 50 per cent was 3.2 per cent in 1994 and 1995.

Graph data (.csv, 1KB)

The Herbert catchment is the second wettest of the areas reported (1239 millimetres mean annual rainfall).

Graph data (.csv, 1KB)


Catchment pollutant loads

Nitrogen

Nitrogen 19% - Poor resultTarget: 50 per cent by 2013.
The estimated annual average total nitrogen load leaving catchments reduced by eight per cent (512 tonnes) by June 2013, up from five per cent (325 tonnes) by June 2012. Agricultural fertiliser use is a key source of dissolved inorganic nitrogen. The estimated annual average dissolved inorganic nitrogen load leaving catchments reduced by 13 per cent (257 tonnes) by June 2013.

Phosphorus

Phorphorus 19% - Poor resultTarget: 50 per cent by 2013.
Agricultural fertiliser use is a key source of phosphorus. The estimated annual average total phosphorus load leaving catchments reduced by 19 per cent (189 tonnes) by June 2013, up from 10 per cent (98 tonnes) by June 2012.

Pesticides

Pesticides 26% - Moderate resultTarget: 50 per cent by 2013.
The estimated annual average pesticide load leaving catchments reduced by 26 per cent (2230 kilograms) by June 2013, up from 14 per cent (1205 kilograms) by June 2012.

Sediment

Sediment 13% - Very good resultTarget: 20 per cent by 2020.
The estimated annual average suspended sediment load leaving catchments reduced by 13 per cent (96,400 tonnes) by June 2013, up from six per cent (45,300 tonnes) by June 2012. The large reduction is attributable to the increase in A class management practice area for 2013.

Graph data (.csv, 1KB)

Note: Land management changes in the horticulture and dairy industries have not been modelled.


Marine

Water quality

Inshore water quality (assessed by remote sensing of chlorophyll a and suspended solids) in the Wet Tropics region remained poor in 2011-2012 and 2012-2013. Scores for chlorophyll a were consistently worse than those for suspended solids in all monitoring years.

Chlorophyll a was rated as very poor in both 2011-2012 and 2012-2013. Concentrations exceeded the Great Barrier Reef Water Quality Guidelines for 95 and 53 per cent of the inshore area in the dry and wet season, respectively, in 2012-2013. Total suspended solids were rated as moderate in 2011-2012 and good in 2012-2013; however, concentrations exceeded the guidelines for 54 and 20 per cent of the inshore area in the dry and wet seasons, respectively, in 2012-2013.

Water quality across the region showed a clear gradient of improvement from inshore areas more frequently exposed to flood waters to offshore areas.

Trend in the Water Quality Index from 2011-2012 to 2012-2013. The Water Quality Index is also separated into component scores for concentrations of chlorophyll a and total suspended solids. Trend data is only shown for these two years, because a major change in the remote sensing algorithms mean the historical data is no longer directly comparable. The full historical time-series will be reprocessed for the next report card.

Graph data (.csv, 1KB)

This onshore-offshore gradient was supported by long-term assessments of water quality at specific sites, with variability between sites reflecting local hydrodynamic conditions and biophysical processes. Site-specific water quality was rated as either good or very good at eight out of 11 sites in the region, three of which are located in the midshelf water body. However, water quality at the three sites close to river mouths draining from highly developed catchments was rated as moderate or poor due to high concentrations of particulate phosphorus, chlorophyll and turbidity/water clarity that exceeded the Great Barrier Reef Marine Park Water Quality Guidelines in 2011-2012 and 2012-2013. These site-specific water quality scores are calculated using a long-term integrated assessment of four indicators of water quality relative to the Great Barrier Reef Water Quality Guidelines (GBRMPA 2010).

Scores for site-specific water quality and pesticides at fixed monitoring sites in the Wet Tropics region.

Concentrations of photosystem II (PSII) herbicides were above those known to affect photosynthesis in diatoms (Category 4) at Fitzroy, Normanby and Dunk Islands. The highest PSII herbicide equivalent concentration in flood waters (Category 3) was detected in grab samples collected near the Tully River mouth following a flow event, and lower concentrations (Category 4) were detected in flood waters from the Herbert River. The range of pesticides detected in the Wet Tropics region in 2012-2013 included diuron, atrazine (and its breakdown products), hexazinone, simazine, tebuthiuron, metolachlor, terbutryn, ametryn, galaxolide, imidacloprid and imazapic. Diuron was present at the highest concentrations. When compared to 2011-2012, diuron and atrazine were detected in greater abundance, by average factors of 2.2 and 8.4, respectively.

Seagrass

The overall condition of inshore seagrass in the Wet Tropics region remained very poor in 2011-2012 and 2012-2013, and has generally been poor since 2005-2006. This is due to complex interactions between the three indicators of seagrass condition: abundance, reproductive effort and nutrient status which are highly variable between years and habitats.

Graph data (.csv, 1KB)

Dominant influences on seagrass communities in the Wet Tropics region include elevated temperatures, seasonal run-off and disturbance from wave action and associated sediment movement. The abundance of inshore seagrass in both coastal and reef habitats in the Wet Tropics remained very poor overall, although there were localised increases in the abundance of fast-growing pioneer species at some sites. Reproductive effort across the region remained very poor in 2012-2013 and there is little evidence of recovery of meadows that were directly affected by Cyclone Yasi in 2011. The very low abundance coupled with very low reproductive effort of seagrass in the region indicates that meadows will be at risk from further impacts and will take many years to fully recover even if conditions were optimum. Leaf tissue nutrient ratios were rated poor overall, indicative of poor water quality.

Graph data (.csv, 2KB)

Graph data (.csv, 1KB)

Graph data (.csv, 1KB)

Graph data (.csv, 1KB)

Coral

The overall condition of inshore coral reefs in the Wet Tropics was poor in 2011-2012 and 2012-2013, and the underlying scores decreased markedly from 2009-2010. In the northern Wet Tropics, coral reef communities declined to poor condition in the Barron Daintree area and remained in moderate condition in the Johnstone Russell-Mulgrave area, while those in the more southerly Herbert Tully area remained in poor condition.

Graph data (.csv, 1KB)

In the more northerly reefs of the Barron-Daintree and Johnson Russell-Mulgrave areas, high levels of coral disease in 2010 and 2011 resulted in slow rates of coral cover increase that, in combination with an increase in crown-of-thorns starfish outbreaks, have reduced coral cover. The density of juvenile corals also declined to low levels in these sub-regions. Coral cover remained very low in southerly reefs in the Herbert Tully area, following severe reductions caused by Cyclone Yasi in 2011. However, an increase in the number of juvenile corals indicates some level of recovery. There has been an increase in the cover of macroalgae in all sub-regions, which contributed to the overall poor condition assessment of reefs in the Wet Tropics.

Graph data (.csv, 1KB)

Graph data (.csv, 1KB)

Graph data (.csv, 1KB)

Average cover of hard corals, cover of macroalgae and density of hard coral juveniles in the Wet Tropics region from 2005 to 2013.

Last updated:
31 March, 2015
Last reviewed:
8 September, 2014

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