It might look like a conspicuous creature but it took Matt Kleczkowski years to capture a mantis shrimp.
The Perth marine scientist and photographer has spent the past decade night-diving in the Swan River but only recently came close enough to take the picture.
“I had dived for a few years but never seen one,” he said. “They are very fast-moving and quite shy.”
Prawns, squid, flathead, blowfish, starfish and anemone are among the species Mr Kleczkowski photographs on his night dives. He regularly encounters “blenny” or Ecsenius australianus, a pint-sized fish that may live in a champagne bottle.
“I dive in Mosman Bay and I photograph blennies in champagne bottles that have fallen off boats,” Mr Kleczkowski said.
“Glass is litter but it can be a great habitat.”
He has snorkelled and fished in the river since he was six and says he has noticed an increase in blowfish.
“When I was younger I remember being able to catch bream a lot more,” Mr Kleczkowski said. “Now there are a lot more blowfish.”
A common response when he tells his friends about his endeavours is “are you crazy?”.
“People get surprised when I tell them I dive in the Swan and they say ‘isn’t it contaminated?’,” Mr Kleczkowski said.
“But in the downstream areas it is quite flushed. I dive in Mosman Bay where it is quite saline, so I see a lot of marine as well as estuarine species.”
Algal blooms in the Swan River have prompted health warnings in the past.
The Department of Biodiversity, Conservation and Attractions said a flood in February last year caused a bloom and was still having an impact.
“The Swan-Canning riverpark is in generally good condition,” a spokeswoman said. “The river is still being influenced by the flood event, (which) resulted in a large drop in the salinity of much of the system and areas of low oxygen across the month or so after the flood eased.
“The flood also resulted in a larger than normal build-up of algal and seagrass matter along some river beaches.”