By Mary Gardner
Every day, I look at the frame we picked up at the neighbours’ garage sale. They knew little about it except that years ago, a relative collected seashells and made this assemblage.
When medieval European philosophers pondered seashells, they debated whether art imitates nature or nature art. Naturalists of the 18th and 19th centuries argued about the first scientific names and classifications of such molluscs. But I am left with a more bleak and bewildering task. Where have all the shellfish gone?
From 540 million years ago, bivalves (with two shells) inhabited marine waters. A hundred million years ago, bivalves called rudists built great reefs in waters warmer and saltier than now. When the asteroid wiped out dinosaurs, the seas cooled. These bivalves went extinct, leaving coral to do the rebuilding in the new tropical seas. But new species boomed: many kinds of oysters, clams and mussels.
Oysters built reefs on firm substrates throughout the temperate zones of the marine world. Clams and mussels spread, filling the beds of lakes, lagoons and waterways. They filled the sandy beaches and subtidal areas out to the hydrothermal vents of the deep ocean. Down where dead whales finally sank, they bored into these bones.
From about 125,000 years ago, people were eating oysters and clams. So far, the oldest material proof is a collection of stone tools found in a fossil reef on the Red Sea coast of Eritrea. Living along the shore means that young and old had easy access to high quality food, rich with protein, omega oils and nutrients.
Some specialists believe that in harvesting this and other seafood, people became smarter. Well fed, they learned about the tides and currents, the moon and the behaviours of fish. They created nets, hooks and watercraft. They met with whales and dolphins. Perhaps the marine mammals used their extraordinary ultrasound capacities and recognized the creatures on the shore as kin.
About 6,000 years ago, the Northern Rivers coastal strip stabilised. Aboriginal Australians befriended dolphins and fished together. People harvested shellfish in spectacular numbers. Not only did women and children collect oysters in season, they also helped extend the beds and reefs. They returned empty shells to the edges, encouraging new young oysters to settle and grow.
The women reburied clutches of surf clams and other species for easier access and to replenish areas. They worked with the men so that certain dead trees were stable deep in the waters of the Belongil, Tallow, Brunswick and Richmond. They were encouraging burrowing clams that grew in this water-soaked wood. They even brought tastier species from one waterway to another, knowing these could spread.
The few remaining middens of shells at the Pass and at Tweed, Brunswick, Lennox, Ballina and Evans Head tell part of this coastal story.
The subsequent invasion by Britain dating from the early 1800s was the first blow for Aboriginal Australians, their shellfish and middens. Oysters were appropriated by the colonists. Surf clams were renamed pipi. At first, these were considered best as bait, or an emergency meal. But when money could be made, they were labelled a fishery. As for the burrowing clam: ‘cah-bro’ was called ‘shipworm’ and treated as a marine pest.
Only since the 1960s have Aboriginal Australians been counted as citizens throughout their country. Only since 2000, have scientists labelled oysters, surf and burrowing clams as ‘foundation species’, structuring habitat for many other marine animals as well as being food for them.
Local oyster reefs and middens were lost to cement-making and commercial over-exploitation. Sand mining plus over-exploitation destroyed many beds of surf clams and more middens. The draining of wetlands and deteriorating quality of waterways likely decreased the populations of burrowing clams. These are yet to be assessed here as important local food.
But this story is not complete. I mention only a few shellfish of the many seen in the assemblage.
Also, the plot has a twist. In the past few years, scientists and communities, First Nations and later arrivals together, have started bold projects. Oyster reefs are deliberately rebuilt. Clam beds are reseeded.
Investigating burrowing clams of Cumbebin swamp and elsewhere in Byron shire might be our first step. We may yet learn again how to live as coastal people, supporting marine animals and each other even as we ourselves are supported.