RESUMO

Climate change is reshaping biological communities, as species track environmental temperature. Assemblage reorganization is underpinned by shifts in species abundance and distribution, but studies often focus on documenting compositional turnover. As a consequence, phenomena such as the tropicalization of temperate communities have been widely associated with increased occupancy of warm-affinity species. Abundance-weighted change in thermal affinity can be tracked with the Community Temperature Index (CTI), and decomposed into four processes: tropicalization (increasing warm-affinity), borealization (increasing cold-affinity), deborealization (decreasing cold-affinity), and detropicalization (decreasing warm-affinity). Further evaluation of these processes according to species persistence (i.e., immigrant, emigrant, and resident) may provide insights on whether novel communities emerge primarily from local shifts in species abundance or distribution. Using long-term data on fish assemblages undergoing climate change's effects across 19 temperate estuaries surveyed for at least 20 years, we hypothesized (1) deborealization is the main process reshaping communities under climate change, and (2) the contribution of resident species to processes reshaping communities surpass the ones from immigrants and emigrants. Community dissimilarity was calculated through the Temporal Beta Index (TBI), which was further decomposed into species and individual losses and gains. These values were then used as effect sizes in the meta-analyses performed to detect systematic trends in assemblage reorganization in response to climate change. We also calculated CTI and the strength of temperature-related processes for resident, immigrant and emigrant species. Species and individual gains outweighed losses in estuaries. Temperature was correlated with changes in species abundance, but not occurrence. Fish abundance decreased with warming, and initially cooler estuaries gained more fish than warmer ones. Novel communities were shaped by a variety of processes, but mainly tropicalization. Assemblage reorganization was primarily driven by shifts in abundance of resident species with distinct thermal affinities, while contributions of arriving and exiting species played a secondary role. These findings reveal that novel communities are drawn primarily from the local species pool, due to changes in climate-related drivers that favor distinct resident species.

Assuntos

RESUMO

Canola (Brassica napus L. var oleifera) is a potential crop due to the growing world demand for vegetable oil. This work aims to evaluate the performance of five canola hybrids in three sowing dates in Jataí-GO. The experiment was conducted in the year of 2017, in a randomized block design, with subdivided plots and four replications. Plots were composed by three sowing dates (03/03, 03/10 and 03/17) and subplots by the canola hybrids Hyola 50, Hyola 61, Hyola 433, Hyola 571CL and Hyola 575CL. Seedling emergence, inicial and final plant population, flowering, maturation, plant height, plant survival index and grain yield were evaluated. The thermal sum calculation was performed with the phenological data. Results were submitted to analysis of variance and means were compared by Scott Knott test at 5% of probability. The plants survival index highlighted Hyola 433, Hyola 571CL and Hyola 575CL hybrids. Grain yield varied according to hybrid and sowing date. In the edaphoclimatic conditions of this study, in the year of 2017, the best agronomic performance was observed in the first sowing date for the canola hybrids Hyola 433 and Hyola 575CL and in the second sowing date for the canola hybrid Hyola 571CL. (AU)

Canola (Brassica napus L. var oleífera) é uma cultura de potencial devido a crescente demanda mundial por óleo vegetal. Diante disso, objetivou-se com este trabalho avaliar o desempenho de cinco híbridos de canola, em três épocas de semeadura em Jataí-GO. O experimento foi conduzido em delineamento de blocos casualizados, com parcelas subdivididas com quatro repetições. Nas parcelas foram avaliadas as três épocas de semeadura (03/03, 10/03 e 17/03) e nas subparcelas os híbridos (Hyola 50, Hyola 61, Hyola 433, Hyola 571CL e Hyola 575CL) no ano de 2017. Foram avaliadas: emergência de plântulas, populações inicial e final, florescimento, maturação, altura de planta, índice de sobrevivência de plantas e produtividade de grãos. Com os dados fenológicos foi realizado o cálculo da soma térmica. Foram efetuadas as análises de variância e as médias foram comparadas pelo teste de Scott Knott a 5% de probabilidade. Para o índice de sobrevivência, destacaram-se os híbridos Hyola 433, Hyola 571CL e Hyola 575CL. A produtividade variou de acordo com híbrido e época. Nas condições edafoclimáticas deste estudo, no ano de 2017, o melhor desempenho agronômico foi observado na primeira época de semeadura para os híbridos de canola Hyola 433 e Hyola 575CL e na segunda época de semeadura para o híbrido de canola Hyola 571CL. (AU)

Assuntos

RESUMO

Interactions among species are likely to change geographically due to climate-driven species range shifts and in intensity due to physiological responses to increasing temperatures. Marine ectotherms experience temperatures closer to their upper thermal limits due to the paucity of temporary thermal refugia compared to those available to terrestrial organisms. Thermal limits of marine ectotherms also vary among species and trophic levels, making their trophic interactions more prone to changes as oceans warm. We assessed how temperature affects reef fish trophic interactions in the Western Atlantic and modeled projections of changes in fish occurrence, biomass, and feeding intensity across latitudes due to climate change. Under ocean warming, tropical reefs will experience diminished trophic interactions, particularly herbivory and invertivory, potentially reinforcing algal dominance in this region. Tropicalization events are more likely to occur in the northern hemisphere, where feeding by tropical herbivores is predicted to expand from the northern Caribbean to extratropical reefs. Conversely, feeding by omnivores is predicted to decrease in this area with minor increases in the Caribbean and southern Brazil. Feeding by invertivores declines across all latitudes in future predictions, jeopardizing a critical trophic link. Most changes are predicted to occur by 2050 and can significantly affect ecosystem functioning, causing dominance shifts and the rise of novel ecosystems.

Assuntos

RESUMO

Seagrasses may enhance the abundance and diversity of benthic invertebrates through trophic facilitation. We investigated this potential ecological function for two seagrasses in SE Brazil: Halodule emarginata, a native species, and Halophila decipiens, a tropical seagrass recently established in the region. At Halophila sites, the organic matter (or carbon) in sediments decreased steadily from seagrass patches to isolated bare grounds, indicating surplus primary production. This was not observed at Halodule sites. At one of the two Halophila sites, localized trophic enrichment was also consistently linked to increased invertebrate abundance within patches, chiefly through increased carrying capacity of small mesoherbivores. Rather than spillover, edge effects were observed at bordering bare habitats, where polychaete predators were abundant. The transition from seagrass edges to isolated bare habitats was marked by an increase of the density of sipunculid worms. The current spread of Halophila may thus change the spatial distribution of benthic ecological functions.

Assuntos

RESUMO

Winter climate change is expected to lead to the tropicalization of temperate ecosystems, where tropical species expand poleward in response to a decrease in the intensity and duration of winter temperature extremes (i.e., freeze events). In the southeastern United States, freezing temperatures control the northern range limits of many invasive nonnative species. Here, we examine the influence of freezing temperatures and winter climate change on the northern range limits of an invasive nonnative tree-Schinus terebinthifolius (Brazilian pepper). Since introduction in the 1800s, Brazilian pepper has invaded ecosystems throughout south and central Florida to become the state's most widespread nonnative plant species. Although Brazilian pepper is sensitive to freezing temperatures, temperature controls on its northern distribution have not been adequately quantified. We used temperature and plant occurrence data to quantify the sensitivity of Brazilian pepper to freezing temperatures. Then, we examined the potential for range expansion under three alternative future climate scenarios (+2°C, +4°C, and +6°C). Our analyses identify a strong nonlinear sigmoidal relationship between minimum temperature and Brazilian pepper presence, with a discrete threshold temperature occurring near -11°C. Our future scenario analyses indicate that, in response to warming winter temperatures, Brazilian pepper is expected to expand northward and transform ecosystems in north Florida and across much of the Gulf of Mexico and south Atlantic coasts of the United States. These results underscore the importance of early detection and rapid response efforts to identify and manage the northward invasion of Brazilian pepper in response to climate change. Looking more broadly, our work highlights the need to anticipate and prepare for the tropicalization of temperate ecosystems by tropical invasive species.

Assuntos