Conclusion - The Great Barrier Reef: An Environmental History - page 227

several ways. First, environmental histories of this type can potentially be used
to identify ecological baselines against which subsequent environmental changes
may be assessed. Second, this account provides evidence of some activities (such
as coral mining) in the Great Barrier Reef that were previously little-known, if not
entirely forgotten, yet which have nevertheless left imprints on the landscapes
of some reefs and islands. Third, this topic contains salutary lessons, such as the
fact that unsustainable industries (such as the commercial humpback whale
fishery based at Tangalooma) can very rapidly - and perhaps catastrophically
- deplete marine populations, even in the presence of regulation and scientific
monitoring of the industry. Yet the scale and intensity of the depletion that
probably characterised other, unregulated and unmonitored fisheries, especially
during the early period of European exploitation of the Great Barrier Reef,
might have eclipsed even those managed fisheries, with unknown ecological
consequences. Therefore, effective, scientific management of reef resources is
critical if the World Heritage values of the Great Barrier Reef are to be protected,
and for some marine species there may now be no sustainable harvest. Fourth, the
evidence assembled in this topic suggests that the cumulative, localised impacts
of many relatively small activities (such as coral and shell collecting), over many
decades, was probably not negligible; on the contrary, they probably transformed
some coral reef areas, albeit in ways that were imperceptible to contemporary
observers. Hence this account provides evidence in support of the concept of
shifting baselines, where successive generations of observers fail to notice that an
environment or ecosystem is gradually changing, and each generation adopts a
new sense of what represents normality for that environment or ecosystem. Many
documentary and oral history sources attest to the problem of shifting baselines;
my research showed that, without the use of scientific methods, only very few
privileged observers - typically those with access to detailed records spanning
several years (if not decades) - were able to detect environmental changes
reliably in the Great Barrier Reef.
Finally, this environmental history suggests that, whilst individual human
impacts (such as military target practice at the Fairfax Islands) can be unequivocally
destructive, in many cases it is the interplay of multiple activities and impacts that
has created particular outcomes for the reefs, islands and organisms of the Great
Barrier Reef. Thus, one of the earliest European impacts in the Great Barrier Reef
- the construction of the navigation beacon at Raine Island in 1844, together
with the subsequent guano mining at that cay - continues, as an unintended
consequence, to cause environmental problems today. This is because the mining
and quarrying activities created small cliffs that now present hazards to the
green turtles that come ashore on the island to nest. The problem is particularly
acute because the cay is the largest and most important green turtle rookery
in the world; it therefore plays a critical role in maintaining the population of
this vulnerable species. Moreover, the problem of additional turtle mortality at
Raine Island is compounded by the increasingly frequent flooding of green turtle
nests by seawater, driven at least in part by rising sea level, which results in the