Charting your future by examining the past; Using historical records and maps to describe Fiji’s habitat change since the 1800s

Blog written by Katherine Newcomer Lawson. Read the full paper here.

How do we tell stories that were never written down? Old tales passed down from ancestor to child can sometimes take new forms and new patterns and absorb new meaning in new times when heard by fresh ears. Some stories are forgotten while others no longer resemble the original tale. When this happens to stories of our own past, it can hinder our understanding of the present. Those who cannot remember the past are condemned to repeat it.

When we tell misremembered stories about the natural world, it causes “Shifting Baseline Syndrome.” Communities forget what large groves of trees looked like, how many whales were once in the ocean, and which species used to be where, and we warp our own understanding of what a healthy ecosystem looks like. Then when we try to protect our oceans, forests, and fields, no one now living remembers what they were like before.

As we attempt to respond to climate change and protect the natural world, conservationists and local governments are looking for data to help set the standard for what healthy ecosystems were like in the past. In some places, new tools like carbon dating and sediment coring can reveal glimpses into ecosystems of the past, but these methods can be expensive and difficult to use widely. Many communities hold traditional ecological knowledge (TEK) that can detail how ecosystems have changed over time. However, due in part to ongoing colonial dispossession, this TEK is threatened as communities lose their close ties to the natural world or as the tradition of passing down TEK to younger generations is weakened. In Pacific Island States like Fiji—a place with a long history of local conservation efforts but a lack of long-term spatial data—settling accurate baselines using historical, non-traditional data sources can supplement local efforts to protect the coast.

In order to supplement current knowledge in Fiji and help inform conservation decisions, we used historical navigational charts (Fig. 1), notes and journal entries from explorers and colonizers, and photographs and drawings to better understand how Fiji has changed over the past century and a half. Historical charts and other documents are a creative source of biological information, and our study is one of the first examples of the many ways we can quantify ecological spatial data from these non-traditional sources. We used advanced geographic software to georeference older navigational charts and compare the change in coral reef area and mangrove coastlines from the 1800s to today. Our results have been recently published in the peer reviewed journal Ecology and Evolution (Lawson et al. 2021).

Fig 1. Chart of Fiji from 1840 U.S. Exploring Expedition. Rough detail of coral is outlined in Suva Harbor.

Wilkes, Charles, and United States Exploring Expedition. Suva Harbour [Cartographic Material] : South Side of Viti Levu, 1840 / by the U.S. Exploring Expedition Led by Charles Wilkes. U.S. Exploring Expedition], 1840. Accessed via the Library of New South Wales.

Our results show that specific, quantitative data can help reveal the impact that human activity has had on an ecosystem. Coral habitats in Suva did not greatly change over the course of our study. In contrast, coral habitats near Savusavu saw major losses in both nearshore reefs and across all of Savusavu Bay, which lost 2933 hectares of reef area from 1880 to 2018. In Suva, mangroves represented 79% of the coastline in 1898, but just 35% by 2019. Simultaneously, hardened coastline in Suva grew from 9% to 58%. While we didn’t see major mangrove loss in Savusavu, hardened shoreline increased significantly in 1966 from 7% to 51% of the shore, replacing other forms of natural coastline, like agriculture or coconut groves (Fig. 2).

Fig 2. Postcard rendition of Savusavu Bay, showing mostly plains and coconut groves on the shore, rather than dense mangroves.

Picturesque Fiji, Melbourne: Algred Martin Ebsworth, Artwork, Print published in the Australasian sketcher, Accession no: A/S27/12/88/204, State Library of Victoria, https://viewer.slv.vic.gov.au/?entity=IE786850&mode=browse

These findings suggest that the coastal environments of Suva and Savusavu have become degraded over a century and a half of commercial use. Our results reflect the complex and often idiosyncratic nature of ecological systems and reinforce the need for quantifiable data from historical sources. It’s possible that coral in Suva has not been majorly impacted by the increase in urbanization seen in the country’s major port, a potential bright spot in our work. We did see overall losses in mangrove and increases in hardened shoreline, but extensive mangrove distribution from the 1800s points towards potential suitable habitat for regrowth and conservation efforts (Fig. 3).

Fig 3. Photo of Suva from Charles Kerry in 1890, showing mangroves and a naturalized shoreline before the development of Suva for industrial shipping.

View in Suva, Fiji approximately 1890 by Charles Kerry, Kerry & Co Photo 308 Geo St. Sydney. Bib ID 7248757, National Library of Australia, https://catalogue.nla.gov.au/Record/7248757

Historical ecology analyses are complicated. As historical ecologists, our work depends on the largesse and expertise of our predecessors and there is often much we cannot know about our sources yet accessing non-traditional data can be a useful approach towards marine conservation biology. Historical charts offer otherwise unavailable glimpses into the past and offer potential pathways for the future.

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