The Department of Biodiversity, Conservation and Attractions (DBCA) advises that elevated levels of algae have been detected in the Swan and Canning rivers. The algae can provide reddish-brown water discolouration and could influence fish kills upstream of Maylands to Middle Swan in the Swan River.

Elevated algae levels have also been detected in the Canning River from Shelley Bridge to Kent Street Weir. This algae can produce toxins that can impact fish by damaging their gills and in severe cases, may cause fish deaths. Blooms of this algae can also make river water appear a reddish-brown colour.

The long weekend weather forecast of hot weather and light winds could assist these algal blooms to grow. DBCA officers are continuing to monitor the blooms and will keep our key Riverpark stakeholders updated.

Information from members of the public is welcome. Anyone who sees dead or sluggish fish in the Swan and Canning rivers are asked to report this to FishWatch on 1800 815 507 and avoid swimming in that area.

The public is also advised to not collect dead fish and to prevent their dogs from consuming dead animals that may appear along the river foreshore.

Wasted Waterways Clean Up Day.

Help clean up Australian waterways on Clean Up Australia Day to keep our beautiful riverways clean and healthy. 

You can register your event here to give back to the environment and the plants and animals who call it home. These wasted Waterways events are happeing all over Australia on Sunday 7th of March 2021 and are a great way to get the community involved in caring for your local waterway. 

So register your event, take lots of photos, tag us and use #cleanourrivers and #cleanupaustraliaday and give back by cleaning our rivers.

Monday 1st of February is the start of Clean our Rivers week and we are encouraging everyone to get down to your favourite riverside location for a few minutes or up to an hour and pick up some rubbish to put in the bin. (This can be done as part of your 1-hour exercise period each day - please ensure you're wearing a mask as it is now mandatory to wear one when you're outside until 6pm on Friday 5 February) 

Show everyone the difference you’ve made by sharing photos of the rubbish you’ve collected to the River Guardians Facebook or Instagram pages (@RiverGuardians) and use the hashtag #cleanourrivers.

Some great news has arrived from Point Walter Spit. The vulnerable Fairy Tern which uses this habitat for nesting has recorded an estimated 150 nests with eggs or small chicks for this breeding season.

These migratory birds build their nests on the beach, leaving them exposed to disturbances such as humans and predators. If the birds are disturbed frequently, they may abandon their nests, resulting in nest failure. With the help and support from Department of Biodiversity, Conservation and Attractions and the City of Melville, several conservation management actions have improved nesting and breeding success, leading to a record number of breeding pairs being recorded at Point Walter Spit this season.

The breeding season is still in full swing, so please continue to avoid the spit for the next few months, to keep the area a safe habitat for these nesting birds.

Freshwater Skin Disease (FWSD) is due to the detrimental effects of freshwater exposure in coastal bottlenose dolphins, and is an emerging cause of morbidity and mortality in many regions. We, for the 1st time, provide a case definition of this disease entity based on two Australian mortality events. The 1st affected Burrunan dolphins (Tursiops australis) in Victoria’s Gippsland Lakes in 2007 (a similar event is currently unfolding - see https://www.abc.net.au/.../burrunan-dolphin.../12900270). The 2nd event occurred in 2009 and affected the resident Indo-Pacific bottlenose dolphins (T. aduncus) in WA's Swan-Canning Riverpark. Simultaneously with the Gippsland Lakes event, the first outbreak of FWSD in US waters was recorded for common bottlenose dolphins (T. truncatus) entrapped in Lake Pontchartrain, Louisiana, USA, following Hurricane Katrina in 2007. However, the dermatopathology was not described for the US event, as post-mortem examinations were not conducted.

By contrast, the Australian events occurred where the resident populations were well documented by long-term and ongoing field ecology, population, and behaviour studies (including Citizen Science projects e.g. WA's River Guardians and Dolphin Watch programs); the waters inhabited by the dolphins were intensively monitored for physical and chemical parameters before, during and after the events; and when mortalities occurred, thorough and systematic post-mortem examinations were carried out. Based on these data, FWSD occurs when there is a sudden (over days) and precipitous (>25ppt to <5ppt) decrease in salinity, persisting for weeks to months. The skin lesions initially appear as patchy pale areas that progress to raised targetoid areas of ulceration and opportunistic colonisation by algae, diatoms, fungi and bacteria. In our paper we detail the gross and histological appearance of the characteristic skin lesions of FWSD. Death may ensue from fluid loss and electrolyte imbalance - because the ulcerative skin lesions are akin to severe third degree burns and often affect a large % of the body surface.

In Australia, the outbreaks followed resumption of seasonal rainfall following a prolonged drought that flooded the Gippsland Lakes (normally brackish to marine saline) with fresh water. In WA, unusually high winter-spring rainfall in the river catchments similarly turned a normally marine/brackish habitat to freshwater. In the Gulf of Mexico, USA, events have followed the heavy rainfall and storm surges in the aftermaths of Hurricanes Katrina and Harvey. Common to all events is a preceding extreme weather event - which are predicted to increase in frequency and severity with Climate Change. Therefore, FWSD is an emerging disease of cetaceans which we are likely to see increasing in frequency in vulnerable estuarine and coastal habitats that continue to be affected by worsening Climate Change.

The research paper is titled ‘Fresh water skin disease in dolphins: a case definition based on pathology and environmental factors in Australia’ published in Nature Scientific Reports. Read the full paper here.

Photo: Case 3 from the paper, a dolphin from Perth’s Swan-Canning Riverpark that died in 2009 (photo credit – Douglas Coughran, AM, DBCA)