Historical Maps provide insight into a century and a half of habitat change in Fijian coasts

Abstract

Meaningful conservation goals require setting baselines derived from long-term ecological records and information that is rare in many regions of the world. Historical data allow us to shift baselines back in time in order to strengthen conservation outcomes in the future. To explore how different histories of land use and development influenced coastal ecosystems in two Fijian cities (Suva and Savusavu), we compared a series of historical navigational charts. These charts recorded change in coral reef area and coastal mangrove forests, as well as expansions of hardened shorelines. We used geographic information systems (GIS) to georeference and make quantitative comparisons starting in 1,840 in Suva and 1876 in Savusavu. Our findings show that, despite increasing urbanization in the capital Suva, available coral reef habitat has not significantly changed in over 150 years, but development has hastened a nearly 50% loss of mangroves. Meanwhile, in the smaller city of Savusavu, coral habitats suffered significant loss in area and an increase in patchiness. As in Suva, shoreline hardening increased in Savusavu, but this change was not accompanied by a loss of mangroves. Nautical charts provided hitherto unavailable information on the long-term loss and alteration of coastal habitats in Fiji. Historical ecology allows scientists to combat shifting baseline syndrome and set measured standards for conservation objectives.