The functionality and services of the wetlands are being greatly reduced because of the coastal activity of humans. But this process isn’t always obvious to us, and it can be hard for us to notice the harmful impact that we have on the wetlands because we see it as progress.
“We tend to modify a coastal zone for our own gain,” Nathan says. “In terms of urban development, we like to get as close as we possibly can to the coastal zone. Since industry follows people, this means that industrial development is another big thing that happens along the coast. Add our love for recreational and commercial fishing, and you can start to see that we are changing and even removing the services that the wetlands provide to coastal environments.”
Understanding the connectivity and interdependence of freshwater and seascape wetlands as well as our impact on that relationship requires educating ourselves on the cost of our progress. A prime example of what our love for waterfront property can cost is the Mangrove Jack.
The Mangrove Jack is a wildly popular fish among both recreational and commercial fishers. But apart from being considered “good eating”, as Nathan puts it, the Mangrove Jack is quite fascinating for its life cycle. The juvenile Mangrove Jack lives in freshwater areas such as estuaries and mangrove creeks. Once they reach maturity, they move out of these freshwater areas into offshore reefs, where the juveniles will then migrate from nearshore areas, through estuaries and back into freshwater wetlands to complete their lifecycle.
This is a lot of ground to cover for the Mangrove Jack over their life cycle. If the path between freshwater and reef waters was blocked, their life cycle would also be blocked. As we continue to build highways, bridges, and train lines through wetlands and floodplains, we’re reducing the connectivity that allows these fish to live.
“The interconnectedness of the seascape is necessary for the Mangrove Jack just to exist. If that connectivity is lost, then the species is lost as well.”
Dr Nathan Waltham
The Mangrove Jack isn’t the only highly targeted and iconic species at risk. The Barramundi, a staple in tropical Australian environments, also relies on the connectivity of the seascape.
All Barramundi are born in estuaries as males. As they grow and mature, barramundi transform into females (though some remain as males), and will swim towards freshwater floodplains, which provides a rich source of food. When it rains again, both male and female barramundi move downstream to estuaries and coastal areas to reproduce, which thereby completes their lifecycle.
“When we talk about the functionality and the services of wetlands, it can be hard for people to connect with it,” Nathan says. “But the risk of losing two major fish species is a reality that encourages us all to learn more about the importance of the wetlands and how vital it is that we protect them.”