Importance of long-term surveys to monitor ecosystems: the case study of coral reefs in the South Pacific

Long-term surveys provide essential data on ecosystems change, climate trends, and the impact of human activities on ecosystems. Collecting data consistently over extended periods prevents misleading or speculative interpretations linked with interannual variability and reveals shifts those short-term studies might overlook. The CRIOBE – SNO CORAIL conduct numerous monitoring programs in tropical islands in the South Pacific, some of which have been ongoing for more than 50 years. Constantly evolving since 1987, this monitoring covers a vast region, including French Polynesia (with 10 islands across different archipelagos) as well as several neighboring Polynesian island nations (Cook Islands, Kiribati, Pitcairn, Samoa, Tonga). Coral reefs are critical ecosystems for these countries as they provide protection against rising wave submergence in a context of global warming and play and essential role in the economy, both as a driver of tourism and as a primary income source for fisheries and aquaculture. Additionally, they are crucial for the global biodiversity, hosting 25% of all marine species. These surveys allow us to identify trends, helping in developing more accurate models and predictions essential for stakeholders to develop effective mitigation and adaptation strategies. Our findings revealed that coral reef demonstrate a notable level of resilience, with a capacity for regeneration within less than 10 years in the absence of additional stress. However, the increasing frequency in bleaching events along with the global increase of temperature, is inducing a shift in fish communities that could reduce this recovery capacity. Therefore, we need to implement solution that support coral reef recovery to maintain areas large enough and in sufficient health to enable recovery when environmental conditions improve.