Long‐term changes in temperate marine fish assemblages are driven by a small subset of species

• Published in: Global change biology 2022-01, Vol.28 (1), p.46-53
• Main Authors: Gotelli, Nicholas J., Moyes, Faye, Antão, Laura H., Blowes, Shane A., Dornelas, Maria, McGill, Brian J., Penny, Amelia, Schipper, Aafke M., Shimadzu, Hideyasu, Supp, Sarah R., Waldock, Conor A., Magurran, Anne E.
• Format: Article
• Language: English
• Subjects: Animals; baseline; Biodiversity; Community composition; Composition; Dynamics; Ecosystem; Fish; Fishes; long‐term monitoring; Marine fish; marine fish assemblages; Marine fishes; Plants; Primary; Primary s; Species classification; Species composition; temporal beta diversity
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.15947

The species composition of plant and animal assemblages across the globe has changed substantially over the past century. How do the dynamics of individual species cause this change? We classified species into seven unique categories of temporal dynamics based on the ordered sequence of presences and absences that each species contributes to an assemblage time series. We applied this framework to 14,434 species trajectories comprising 280 assemblages of temperate marine fishes surveyed annually for 20 or more years. Although 90% of the assemblages diverged in species composition from the baseline year, this compositional change was largely driven by only 8% of the species' trajectories. Quantifying the reorganization of assemblages based on species shared temporal dynamics should facilitate the task of monitoring and restoring biodiversity. We suggest ways in which our framework could provide informative measures of compositional change, as well as leverage future research on pattern and process in ecological systems. How do individual species contribute to long‐term patterns of compositional change? We devised a canonical classification scheme in which each species in a time series assemblage is assigned uniquely to one of seven different categories (colors) of temporal dynamics. In an analysis of 280 north temperate fish assemblages monitored for 20 or more years, a key result is that only 8% of the species (orange and brown rows) contribute to systematic changes in species composition away from an initial baseline composition (first column).