If you’ve been out this winter, you might have noticed an abundance of cormorants. Did you know, that Bayside cormorants are important for our whole coastline. Protecting and potentially building their populations, will boost fish abundance and improve reef health. If we are going to resore Port Phillip Bay to its former glory, our seabirds are of phenomenal significance, yet often ignored. There is very little information on their abundance and distribution in the Bay. However, it is the seabirds that are helping to maintain fish abundance, as we will discover.
Seabirds and reef health
For a long time we have known about the connection between seabirds and coastal reef health. This study for the Royal Society journal, which is one of the latest roundups of knowledge, says:
Seabird biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More was particularly important for terrestrial and near-shore subsidies and enhancing fish biomass.
Fish biomass translates into better functioning reefs and in turn, a stronger economy. We need reefs that are more resilient to effects like storms and climate. The guano that our cormorants (and other seabirds) create is at the correct ratio to be absorbed by reef life. It’s also at huge concentrations that can even influence local weather. It’s hardly surprising that the amount of guano seen pouring off rocks into the sea, is also a substantial contribution to the regrowth of our coastal seaweeds and coral.
Bayside cormorants
Pied Cormorants, which are our most abundant species, breed on Mud Island and at the Western Treatment Plant. There are 700-1000 breeding pairs in the latter location alone.
The other species generally breed in freshwater lakes and can move in and out of the region seasonally and following inland rains.
Human sewage outflows like what we saw last year, overwhelms reefs. Since we ourselves can’t fertilise reefs effectively, we are dependent on the birds pictured above. Among the many things we can do, is nurture a thriving population and encourage them by creating safe roosts along the coast.
Bayside cormorants are important but this goes too for the variety of other species that call our north shore home, including the Black Swans (pictured). Though I am concerned about one factor, which I’ll explore in another blog: freshwater. It’s plain to see all along our coast and has just caused an enormous die-off of reef life nearby.
