Remote sensing in seagrass ecology: coupled dynamics between migratory herbivorous birds and intertidal meadows observed by satellite during four decades

• Published in: Remote Sensing in Ecology and Conservation
• Main Authors: Zoffoli, Maria, Laura, Gernez, Pierre, Oiry, Simon, Godet, Laurent, Dalloyau, Sébastien, Davies, Bede Ffinian Rowe, Barillé, Laurent
• Other Authors: Istituto di Science Marine (ISMAR ), National Research Council of Italy, Institut Des Substances et Organismes de la Mer - UR 2160 (ISOMER), Nantes Université - UFR des Sciences Pharmaceutiques et Biologiques (Nantes Univ - UFR Pharmacie), Nantes Université - pôle Santé, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Santé, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ), Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes ), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Nantes Université (Nantes Univ)-Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Ligue pour la Protection des Oiseaux (LPO), This research was supported by the BiCOME project (Biodiversity of the Coastal Ocean: Monitoring with Earth Observation) funded by the European Space Agency under ‘Earth Observation Science for Society’ element of FutureEO-1 BIODIVERSITY+ PRECURSORS call, contract No. 4000135756/21/I-EF.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: Branta bernicla bernicla; trophic relationships; Earth observation; essential biodiversity variables; time-series; Zostera noltei; [SDV.EE.ECO]Life Sciences [q-bio]/Ecology; environment/Ecosystems; [SHS.GEO]Humanities and Social Sciences/Geography; Branta bernicla; brent geese; Brent goose
• Online Access: https://hal.science/hal-03905797; https://hal.science/hal-03905797/document; https://hal.science/hal-03905797/file/zoffoli_et_al_clean_version.pdf; https://doi.org/10.1002/rse2.319

International audience Taking into account trophic relationships in seagrass meadows is crucial to explain and predict seagrass temporal trajectories, as well as for implementing and evaluating seagrass conservation policies. However, this type of interaction has been rarely investigated over the long term and at the scale of the whole seagrass habitat. In this work, reciprocal links between an intertidal seagrass species, Zostera noltei, and a herbivorous bird feeding on this seagrass species, the migratory goose Branta bernicla bernicla, were investigated using an original combination of long-term Earth Observation (EO) and bird census data. Seagrass Essential Biodiversity Variables (EBVs) such as seagrass abundance and phenology were measured from 1985 to 2020 using high-resolution satellite remote sensing over Bourgneuf Bay (France), and cross-analysed with in situ measurements of bird population size during the goose wintering season. Our results showed a mutual relationship between seagrass and Brent geese over the four last decades, suggesting that the relationship between the two species extends beyond a simple grass—herbivore consumptive effect. We provided evidence of two types of interactions: (i) a bottom-up control where the late-summer seagrass abundance drives the wintering population of herbivorous geese and (ii) an indirect top-down effect of Brent goose on seagrass habitat, where seagrass development is positively influenced by the bird population during the previous wintering season. Such a mutualistic relationship has strong implications for biodiversity conservation because protecting one species is beneficial to the other one, as demonstrated here by the positive trajectories observed from 1985 to 2020 in both seagrass and bird populations. Importantly, we also demonstrated here that exploring the synergy between EO and in situ bird data can benefit seagrass ecology and ecosystem management.