There are approximately 3,000 square kilometres of coral reefs in the region with approximately 340 hard coral species , 60 genera of soft corals and 1,500 species of fish . Reefs in the Burdekin Region (~ 20 ° S ), together with reefs in the Far Northern region (~ 14 ° S ), exhibit the highest hard coral species richness on the GBR . All reefs in the region are within the Great Barrier Reef Marine Park ( GBRMP ) and zoned General Use , Habitat Protection , Conservation Park , Marine National Park or Preservation Zones .
Seagrasses are a key ecosystem within the Burdekin Region supporting populations of dugong , turtle , seabirds and fisheries of commercial and recreational importance . A composite of seagrass monitoring surveys since 1985 indicates that there are 551 square kilometres of shallow seagrass areas (< 15 m depth ) in the region , which represent 45 per cent of the total shallow seagrass area in the GBR ( excluding the Cape York region ). No estuarine or deep water seagrass communities are monitored in this region , however , they are considered to be present .
The most significant species of conservation concern in the Burdekin Region are dugong , cetaceans , turtles and seabirds . The region includes four Dugong Protection Areas ; Cleveland Bay , Bowling Green Bay , Cape Upstart Bay and part of Edgecumbe Bay . High priority cetaceans in the region include the humpback whale ( vulnerable ), dwarf minke whale ( No Category Assigned ( NCA ) - insufficient information ), Australian snubfin dolphin ( NCA - insufficient information ) and the Indo-Pacific humpback dolphin ( NCA - insufficient information ). The Australian snubfin dolphin and Indo-Pacific humpback dolphin are coastal species that are particularly vulnerable to water quality decline and populations are known to inhabit Cleveland Bay .
Five of the world ’ s seven sea turtle species are likely to occur in the Burdekin Region . Scattered and periodic nesting of Flatback Turtles occurs on mainland and inshore islands between Townsville and Torres Strait . Cleveland Bay is considered an important foraging grounds and juvenile habitat for Green Turtles .
5.3 Influence of Burdekin River discharge , sediments and nutrients within the Great Barrier Reef lagoon
Prominent luminescent lines in massive Porites corals from the central GBR highlight the area of influence of the Burdekin River in the marine environment and also provide a valuable record of historical annual discharge and Queensland rainfall variability ( Hendy et al . 2003 ; Lough , 2007 ; Lough et al . 2015 ). The records show that the inshore reefs of the central GBR ( i . e . fringing reefs of Magnetic Island and the Palm Island Group ) are influenced by Burdekin River discharge most years while mid-shelf reefs such as Britomart Reef are influenced once every five to ten years ( Hendy et al . 2003 ; Lough , 2007 ; Lough et al . 2015 ).
The Burdekin River discharge , and associated particulate constituents , influences photic depth and turbidity on the inner central GBR ( Logan et al . 2013 , 2014 ; Fabricius et al . 2014 ). Specifically , the years following large Burdekin discharge and elevated particulate constituent loads coincided with considerable reductions in photic depth ( Fabricius et al ., 2014 ). In turn , reduced photic depth was implicated in the alarming decline of seagrass meadow area ( 84 % loss ) in Cleveland Bay following a series of large Burdekin flow events from 2007 / 08 to 2010 / 11 ( Petus et al . 2014 ). Furthermore , Fabricius et al . ( 2013 ) has shown that turbidity levels were considerably higher in months following large river inputs than levels following lower river inputs . This finding suggests that the inputs of newly delivered terrestrial materials influence the turbidity regime on the inner GBR which contrasts previous assertions ( e . g . Orpin and Ridd , 2012 ), although newly delivered sediments can be ‘ flushed out ’ of embayments during the dry season and in cyclonic conditions ( Lambrechts et al . 2010 ). In the years since , seagrass has reportedly shown signs of recovery within Cleveland Bay ( R . Coles pers . comm ., 2014 ) following a series of drier
years and relatively lower discharge from the Burdekin River .
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