Browsing by Author "Horta, P. A."
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- Extinction risk of the endemic soft coral Phyllogorgia dilatata (Esper, 1806) in a remote island of the Brazilian coastPublication . Anderson, A. B.; Gouvêa, Lidiane; Assis, Jorge; Serrao, Ester A.; Pinheiro, H. T.; Vilar, C.; Francini-Filho, R. B.; Horta, P. A.; Bernardino, A. F.; Cordeiro, C. A. M. M.; Gomes, L. E. O.; Joyeux, J.-C.; Ferreira, C. E. L.The Brazilian endemic octocoral Phyllogorgia dilatata (elephant ear sea fan) plays a crucial ecological role in the marine ecosystems of the Brazilian coast. Our work investigates the local extinction of P. dilatata on Trindade Island, a remote oceanic island in the Southwestern Atlantic, and assesses the potential impacts of climate change on its distribution. Field surveys conducted over two years (2016-2019) revealed no live individuals of P. dilatata, with only dead peduncles remaining, marking the first observed local extinction of this species. Species distribution models (SDMs) incorporating current and historical climate data were used to estimate the species' habitat suitability and project future distribution under different climate scenarios. Results indicate that P. dilatata currently inhabits approximately 93,090 km2 of suitable area, primarily within tropical ecoregions, but faces significant habitat loss under future climate projections. By 2090-2100, models predict a 63.38 % loss of habitat under the high-emission RCP 8.5 scenario, with severe impacts on tropical regions, including Trindade Island. Environmental variables such as temperature, oxygen concentration, and salinity were identified as key drivers of the species' distribution, while non-climatic factors like seawater velocity, were also significant. The extinction on Trindade Island is attributed to a combination of historical isolation, climate change, and local anthropogenic stressors, including pollution and overfishing. The current investigation highlights the urgent need for conservation efforts, including the establishment of marine protected areas and restoration programs, to protect this vulnerable species and similar marine organisms again climate change.
- Rhodolith primary and carbonate production in a changing ocean: The interplay of warming and nutrientsPublication . Schubert, N.; Salazar, V. W.; Rich, W. A.; Vivanco Bercovich, M.; Almeida Saa, A. C.; Fadigas, S. D.; Silva, João; Horta, P. A.Rhodolith beds, like many other marine ecosystems, are affected by climate change that is causing an increase in the magnitude and frequency of extreme high temperature events (heat waves). Unfortunately, this does not represent the sole peril for these communities, as coastal urbanization in conjunction with altered precipitation patterns can increase terrestrial-derived nutrient input. In Brazil, rhodolith beds are among the most extensive coastal benthic ecosystems, but despite their vast distribution and great ecological and economic importance, studies on the productivity of these communities and the impact of changing environmental conditions are almost non-existent. This study addressed the individual and combined effects of increases in temperature and nutrient concentration on the physiological performance of two widely distributed rhodolith species, Lithothamnion crispatum and Melyvonnea erubescens. The results showed species-specific responses in net photosynthetic performance, with no response in L. crispatum, while M. erubescens responded negatively to both increase in temperature and nutrients. In contrast, calcification in both species showed a significant decline at high temperature. No interactive effects were found between temperature and nutrients, yet their combined negative effects were additive, resulting in negative daily-integrated net productivity and a large decline in daily carbonate production in both species. This has strong implications for rhodolith bed primary productivity and carbonate production, as heat waves may potentially cause a strong decline in carbonate production (ca. 50% loss), accompanied by a severe drop in primary productivity that will be even more pronounced under high-nutrient conditions. Also, the species-specific responses to changes in temperature and nutrient concentration suggest that the magnitude of impact of these factors on rhodolith bed productivity will depend on the species dominating the community and may finally result in changes in rhodolith community composition. (C) 2019 Elsevier B.V. All rights reserved.