Prehistoric baseline reveals substantial decline of oyster reef condition in a Gulf of Mexico conservation priority area

Abstract

The Gulf of Mexico (GoM) is home to the world's largest remaining wild oyster fisheries, but baseline surveys needed to assess habitat condition are recent and may represent an already-shifted reference state. Here, we use prehistoric oysters from archaeological middens to show that oyster size, an indicator of habitat function and population resilience, declined prior to the earliest assessments of reef condition in an area of the GoM previously considered pristine. Stable isotope sclerochronlogy reveals extirpation of colossal oysters occurred through truncated life history and slowed growth. More broadly, our study suggests that management strategies affected by shifting baselines may overestimate resilience and perpetuate practices that risk irreversible decline.

Age and growth of one of the world’s largest carnivorous gastropods, the Florida Horse Conch, Triplofusus giganteus (Kiener, 1840), a target of unregulated, intense harvest

“…This study joins others [ 51 , 52 ] in highlighting how life history information necessary for managing species of threatened or declining mollusks can be obtained through stable isotope sclerochronology. This technique can be applied to specimens in historical museum collections, as we have done here, allowing better understanding of species’ maximum growth potential prior to modern human impacts and doing so without the need for sacrificing animals of already scarce species.…”

“…giganteus , the largest, oldest individuals have not been recorded in any modern surveys, which means application of stable isotope sclerochronology to shells in historic and prehistoric collections [e.g. 52 ] is the only way to study the maximum growth potential of the species. This information bottleneck will only get worse and the need for alternative research approaches more dire as species in need of protection become increasingly uncommon.…”

Indigenous oyster fisheries persisted for millennia and should inform future management

“…Indigenous fisheries were largely sustainable and interwoven with Indigenous people’s worldviews and traditional practices. These fisheries reflected traditional knowledge accumulated by Indigenous peoples over thousands of years that structured technology, harvest practices, and consumption patterns that enabled the incredible yields of the capitalist commercial eras 10 , 11 , 48 , 69 , 70 .…”

History's legacy: Why future progress in ecology demands a view of the past

“…Restoration of the consuming capacity of nearshore ecosystems therefore might go a long way toward managing the high influx of nutrients resulting from human activity, likely leading to a decrease in anoxic bottom conditions and an overall higher productivity of the aerobic ecosystem. This potential mitigation should be considered, given the demonstrated fact that consumer biomass in Chesapeake Bay was vastly greater in the recent historical past than it is today (Hesterberg et al, 2020; Lockwood & Mann, 2019).…”