Estimating adult-stage abiotic suitability and climate-driven distributional shifts for the threatened queen conch (Aliger gigas) in the Caribbean

The queen conch (Aliger gigas) is a key native species of the Caribbean Sea and a primary source of income for thousands of fishers. Historically, it has been a highly valuable resource for the fishing sectors of countries such as the Bahamas, Turks and Caicos, Honduras, and Nicaragua. However, the species has been extensively overfished across the region due to its high economic value and inherent susceptibility to harvest. Overfishing, combined with limited larval dispersal, low recruitment, and poor population connectivity, has led to a drastic decline in population numbers of the species, resulting in its current classification as Threatened. Despite this status, likely impacts of climate change on its populations remain poorly understood, posing significant challenges to conservation efforts. To address this gap, we integrated adult occurrence records with both benthic- and surface-level, data on ocean temperature, salinity and pH to develop ecological niche models evaluating adult-stage abiotic suitability in the Western Atlantic and potential distributional changes under three climate change scenarios of Shared Socioeconomic Pathways (optimistic, moderate, and extreme). Suitability estimates were later analyzed in light of seagrass habitats and the distribution of Marine Protected Areas (MPAs) in the region. Our analyses suggested a high spatial stability in abiotically suitable areas at the benthic level across all time horizons under the optimistic climate change scenario. Conversely, benthic-based models under the moderate and extreme scenarios are less consistent between modeling frameworks and their estimations diverge substantially, impeding accurate interpretations. Surface-derived models estimated substantial losses of abiotically suitable areas for queen conch (i.e., areas projected to transition to abiotic conditions that fall outside of the suitable conditions defined by the recorded occurrences of the species), projecting abrupt declines from 2020–2040 across all climate change scenarios. This work aims to enhance existing knowledge about the abiotic suitability of several areas in the Western Atlantic for queen conch and provide relevant insights about the potential changes in the geographic distribution of the species over the next decades. Ultimately, anticipating future habitat availability will be key for guiding the conservation and management of this economically and ecologically critical species.