Rays digging for shellfish would create a lot of commotion in the shallows.
They are not dangerous, unless you step on them in which case, they may cause you an ugly injury with their tail barb.

So, don't step on them

not wanting to alarm but I recall there were reports of a shark[s] [presumably small bull / SR whaler] taking birds up that way last year early morning. There are some shallow spots where pelicans, terns etc roost at lower tides. Dog walker or similar early morning venturer reported it.

I would not recomend complacency around rays even very small ones ,I trod on one(3 weeks ago at cervantes) buried in the sand as they do, it was about the size of a dinner plate it arched itself over and drove its barb into the top of my foot leaving a cocktail of poisions one that has a cobbler like effect (couple of hrs of intense pain) the other toxins have a necrotic effect killing the flesh in the area, this coupled with the bacteria present even with antibiotics can lead to infection that is very difficult to deal with,amputations are not uncommon as a result of stingray barb wounds in less piveledged parts of the world.I ended up in hospital a week after the wounding, they cut it open scraped all the dead smelly stuff out stitched it up and drained several litres of antibiotics into my arm and sent me home the next day,that was a week ago still got another week of antibiotics to go and another couple of weeks before its healed enough to attempt sailing.Best case at this point will be 6 weeks of the water.
My advice if you every suffer a ray barb go straight to emergency (not to a gp for a antibiotics as I did) where they will treat it more aggressively.

Best wishes for your recovery Recycle.