As algas calcárias crostosas ou CCA (do inglês Crustose Coralline Algae) têm como principal característica a impregnação de carbonato de cálcio em suas paredes celulares. Este grupo é formado atualmente por três ordens, Corallinales, Hapalidiales e Sporolithales, cuja taxonomia é historicamente problemática por se basear na fase tetrasporofítica, fundamental para qualquer identificação até mesmo em nível de ordem. Em virtude disso, diversos estudos, principalmente nos últimos 10 anos, têm incluído ferramentas moleculares como auxílio à taxonomia morfoanatômica deste grupo. O objetivo deste estudo foi investigar a diversidade e a distribuição das CCA ao longo da costa Brasileira, através de dados moleculares e morfoanatômicos. Para isso, foram utilizados quatro marcadores moleculares, UPA, rbcL-3P, COI-5P e psbA, aliados à imagens de microscopia óptica e microscopia eletrônica de varredura, que resultaram na identificação de pelo menos 37 espécies entre Corallinales, Hapalidiales e Sporolithales. Os resultados obtidos a partir das análises de agrupamento dos quatro marcadores demonstraram que as ordens Corallinales e Sporolithales são monofiléticas, e Hapalidiales constitui um grupo não-monofilético (com exceção do marcador psbA, que resolveu a ordem como grupo monofilético). Os resultados também revelaram existência de uma grande diversidade de espécies e gêneros destas ordens no Brasil, além de espécies novas e ao menos um potencial gênero novo para ciência. O estudo também revelou relações filogeográficas entre espécies do Brasil e do Golfo do México e do Indo-Pacífico. Considerando as três ordens de CCA (Corallinales, Hapalidiales e Sporolithales), este estudo representa a primeira tentativa de desvendar de forma mais ampla a diversidade de espécies CCA encontradas ao longo da costa brasileira, utilizando dados moleculares / The Crustose Coralline Algae (CCA) has as a main distinguishing characteristic the calcium carbonate impregnation in their cell walls. This group currently encompasses three orders, the Corallinales, Hapalidiales and Sporolithales, whose taxonomy is historically problematic because it is based on the tetrasporophytic phase, fundamental to any classification, even at the ordinal level. Therefore, many studies, especially in the last 10 years, have included molecular tools to assist the morphological taxonomy of this group. This study aims to investigate the diversity and distribution of the CCA along the Brazilian coast, through molecular and morphoanatomical data. In order to achieve this aim, four markers were used, UPA, rbcL-3P, COI-5P and psbA, allied to light and scanning electron microscopy, that resulted in the identification of at least 37 species between Corallinales, Hapalidiales and Sporolithales. The results of the cluster analyses of the four markers showed that Corallinales and Sporolithales are monophyletic, and Hapalidiales comprises a non-monophyletic group (with the exception of psbA, which resolved the order as a monophyly). Our results also revealed a great diversity of species and genera of these three orders in Brazil, as well as putative new species and at least a new genus. This study also revealed phylogeographic relationships between Brazilian species and species from Gulf of Mexico and from Indo-Pacific oceans. Considering all the three orders of CCA, this study represents the first broad attempt and effort to unveil the diversity of CCA species found on the Brazilian coast using molecular data

As algas calcárias crostosas ou CCA (do inglês Crustose Coralline Algae) têm como principal característica a impregnação de carbonato de cálcio em suas paredes celulares. Este grupo é formado atualmente por três ordens, Corallinales, Hapalidiales e Sporolithales, cuja taxonomia é historicamente problemática por se basear na fase tetrasporofítica, fundamental para qualquer identificação até mesmo em nível de ordem. Em virtude disso, diversos estudos, principalmente nos últimos 10 anos, têm incluído ferramentas moleculares como auxílio à taxonomia morfoanatômica deste grupo. O objetivo deste estudo foi investigar a diversidade e a distribuição das CCA ao longo da costa Brasileira, através de dados moleculares e morfoanatômicos. Para isso, foram utilizados quatro marcadores moleculares, UPA, rbcL-3P, COI-5P e psbA, aliados à imagens de microscopia óptica e microscopia eletrônica de varredura, que resultaram na identificação de pelo menos 37 espécies entre Corallinales, Hapalidiales e Sporolithales. Os resultados obtidos a partir das análises de agrupamento dos quatro marcadores demonstraram que as ordens Corallinales e Sporolithales são monofiléticas, e Hapalidiales constitui um grupo não-monofilético (com exceção do marcador psbA, que resolveu a ordem como grupo monofilético). Os resultados também revelaram existência de uma grande diversidade de espécies e gêneros destas ordens no Brasil, além de espécies novas e ao menos um potencial gênero novo para ciência. O estudo também revelou relações filogeográficas entre espécies do Brasil e do Golfo do México e do Indo-Pacífico. Considerando as três ordens de CCA (Corallinales, Hapalidiales e Sporolithales), este estudo representa a primeira tentativa de desvendar de forma mais ampla a diversidade de espécies CCA encontradas ao longo da costa brasileira, utilizando dados moleculares / The Crustose Coralline Algae (CCA) has as a main distinguishing characteristic the calcium carbonate impregnation in their cell walls. This group currently encompasses three orders, the Corallinales, Hapalidiales and Sporolithales, whose taxonomy is historically problematic because it is based on the tetrasporophytic phase, fundamental to any classification, even at the ordinal level. Therefore, many studies, especially in the last 10 years, have included molecular tools to assist the morphological taxonomy of this group. This study aims to investigate the diversity and distribution of the CCA along the Brazilian coast, through molecular and morphoanatomical data. In order to achieve this aim, four markers were used, UPA, rbcL-3P, COI-5P and psbA, allied to light and scanning electron microscopy, that resulted in the identification of at least 37 species between Corallinales, Hapalidiales and Sporolithales. The results of the cluster analyses of the four markers showed that Corallinales and Sporolithales are monophyletic, and Hapalidiales comprises a non-monophyletic group (with the exception of psbA, which resolved the order as a monophyly). Our results also revealed a great diversity of species and genera of these three orders in Brazil, as well as putative new species and at least a new genus. This study also revealed phylogeographic relationships between Brazilian species and species from Gulf of Mexico and from Indo-Pacific oceans. Considering all the three orders of CCA, this study represents the first broad attempt and effort to unveil the diversity of CCA species found on the Brazilian coast using molecular data

Over the past few decades, coral cover has declined worldwide due to overfishing, disease, and storms, and these effects have been exacerbated by ocean warming and acidification. Corals are extremely susceptible to these changes because they are already living close to their thermal and aragonite saturation thresholds. Ocean warming and acidification (OAW) may also impact coral survival and growth by impacting their settlement cues. Coral larvae use crustose coralline algae (CCA) and their associated biofilms as cues for settlement, i.e., habitat selection. Settlement cues can also be negatively affected by increased water temperature and acidity. It was hypothesized that the impacts of OAW on settlement substrate can further threaten coral persistence by altering/inhibiting larval settlement and potentially decreasing the post-settlement survival and growth of coral recruits. In this study, we 1) assessed the effect of substrate quality (substrate conditioned in ambient or OAW conditions) on settlement of A. agaricites larvae, 2) determined the effect of substrate quality on post-settlement survival and growth of A. agaricites recruits, and 3) determined the effect of ocean warming and acidification on the post-settlement survival and growth of A. agaricites recruits. Aragonite settlement tiles were placed offshore for one month to accrue CCA and associated biofilms, and were then conditioned in either ambient (29°C, 8.2 pH) or predicted future oceanic conditions (31°C, 7.9 pH) conditions for 7 – 10 days. Agaricia agaricites larvae were then introduced to the settlement tiles, and their settlement percentage was calculated. Once a week for 12 weeks after larval settlement, the size, survival, and pigmentation of A. agaricites recruits was recorded. Larvae settled marginally more on optimally conditioned tiles than on tiles previously exposed to OAW conditions (p=0.053). The survival of coral recruits in OAW conditions was greatly reduced, their growth was very limited, and they became paler over time. When reared in ambient conditions, recruits on OAW treated substrate initially displayed higher survival rates than recruits on ambient treated substrate. After 3 weeks in ambient conditions, however, survival rates were similar for recruits on ambient and OAW treated substrate; their growth curves were very similar, and coral recruits became more pigmented over time. Ocean warming and acidification conditions not only directly impacted the growth, survival, and pigmentation of A. agaricites recruits, but it also indirectly affected larval 5 settlement by likely altering microbial composition in bacterial biofilms on the settlement tiles. These results indicate that future conditions of ocean warming and acidification can be deleterious for A. agaricites, particularly after settlement. If the early life stages of scleractinian corals are negatively affected by OAW conditions, successful recruitment throughout the Caribbean and Florida Reef Tract could decrease. As a result, recovery from disturbances could be hindered, thus compromising the sustainability of many coral species and other marine ecosystems that depend on coral reefs for protection, habitat, and food.