A changing ocean: model performance and Penaeoidea shrimp responses to climate change in the Western Atlantic
Niche modeling; climate change; habitat suitability; fisheries management; IPCC.
Penaeoidea shrimps sustain fisheries of major socioeconomic relevance in the Western Atlantic, but predictive tools to anticipate their responses to environmental pressures remain scarcely explored for this group, and community-level assessments under multiple future climate scenarios are virtually nonexistent, particularly for economically important species. This thesis addresses these gaps in two stages. Because different modeling algorithms can generate contrasting predictions, relying on a single method can compromise the reliability of the resulting forecasts; in this context, the first chapter investigated whether ecological niche models can be successfully applied to model the distribution of marine shrimps, comparing the performance of five individual algorithms and a general ensemble approach in predicting the current distribution of three economically important penaeid shrimp species. Random Forest, Maxent and Full ensemble showed the best performance and the highest ecological plausibility, confirming the viability of this approach for the group, while numerical model evaluation metrics alone proved insufficient to identify spatially unrealistic predictions, reinforcing the need for complementary visual validation. In the second chapter, this validated approach was applied at a larger scale: the niche of ten Penaeoidea shrimp species was modeled under six future climate scenarios, integrating community diversity, habitat extent, and the trajectory of change along a severity gradient. Results indicated a net gain in expected richness increasing with climate severity, contrasting with the loss predominantly reported in the literature for other marine crustaceans. The observed gain, however, was driven by a few species, while others lost suitability, and even range-expanding species lost high-quality habitat. These results suggest that gains in extent do not necessarily translate into real ecological gains, reinforcing the need for species-specific assessments for the responsible management of this fishery resource in the face of climate change.