The allocation of $95,954 in state funds for Posidonia australis regeneration (Greener pastures for grass, 5/10) creates a public impression that something is being done for the Port’s damaged seagrasses. But it’s too little, too late and obviously misdirected, when recommendations like aerial monitoring of the Flood Tide Delta in the Outer Port (University of Sydney Study 2010) remain unfulfilled. Visiting Marine Ecologist Terry Domico (2003) informs us: ”Seagrass ecosystems are among the most diverse and productive ecosystems in the world. In ecological and economic value they rival tropical rainforests and the richest farmlands. They are a vital natural marine resource supporting near-shore food web relationships”.
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The proposed replanting of seagrass damaged by outmoded chain swing boat moorings is challenging enough but when it comes to the naturally occurring hydrodynamics of tidal, storm and recurring sand events this replanting becomes somewhat doubtful and even futile. A July 2012 Department of Primary Industries factsheet states: “Damaged Posidonia australis plants cease to establish lateral rhizome runners and are very slow to recover, taking up to 50 years to close a gap of 1m following damage”.
While it is important that the replacement of chain swing moorings continues, natural sand inundation is much more challenging and rapidly turning seagrass meadows into sandy beaches.
This is a natural occurring disaster at this time of migrating sands drifting westward and so far impacting our seagrass meadows of mixed seagrass species and more are expected to follow. Similar events from migrating sands have occurred before in the eastern sector of the estuary but have not been addressed with the appropriate actions recommended by marine scientists.
This relentless, inexhaustible source of migratory sand is the natural consequence of a hydrodynamic, unstable and intractable estuary marine system effectively facilitated by the 1.24km entrance attracting big swells of wave energy, consistent south east winds and dynamic east-west tidal flows.
A major allocation of state funds is now urgently needed to address the science-based recommendations arising from extensive studies including those conducted by the University of Sydney led by marine scientist Dr Ana Vila-Concejo et al.
Darrell Dawson is on the Port Stephens Estuary Management Committee and is a Marine Park Advisory Committee member.
