Camila Fernanda DA Silva

The Amapá margin, part of the Brazilian Equatorial Margin (BEM), is a key region that plays a strategic role in the global climate balance between the North and South Atlantic Ocean as it is strictly tied to equatorial heat conveyance and the fresh/salt water equilibrium with the Amazon River. We performed a new scientific expedition on the Amapá continental shelf (ACS, northern part of the Amazon continental platform) collecting sediment and using instrumental observation at an unstudied site. We show here the preliminary outcomes following the applied methodologies for investigation. Geophysical, geological, and biological surveys were carried out within the ACS to (1) perform bathymetric and sonographic mapping, high-resolution sub-surface geophysical characterization of the deep environment of the margin of the continental platform, (2) characterize the habitats and benthic communities through underwater images and biological sampling, (3) collect benthic organisms for ecological and taxonomic studies, (4) define the mineralogical and (5) elemental components of sediments from the study region, and (6) identify their provenance. The geophysical data collection included the use of bathymetry, a sub-bottom profiler, side scan sonar, bathythermograph acquisition, moving vessel profiler, and a thermosalinograph. The geological data were obtained through mineralogical, elemental, and grain size analysis. The biological investigation involved epifauna/infauna characterization, microbial analysis, and eDNA analysis. The preliminary results of the geophysical mapping, shallow seismic, and ultrasonographic surveys endorsed the identification of a hard substrate in a mesophotic environment. The preliminary geological data allowed the identification of amphibole, feldspar, biotite, as well as other minerals (e.g., calcite, quartz, goethite, ilmenite) present in the substrata of the Amapá continental shelf. Silicon, iron, calcium, and aluminum composes ~85% of sediments from the ACS. Sand and clay are the main fraction from these sediments. Within the sediments, Polychaeta (Annelida) dominated, followed by Crustacea (Arthropoda), and Ophiuroidea (Echinodermata). Through TowCam videos, 35 taxons with diverse epifauna were recorded, including polychaetes, hydroids, algae, gastropods, anemones, cephalopods, crustaceans, fishes, and sea stars.

Increasing habitat modification and species loss demand consistent efforts to describe and understand biodiversity patterns. The BIOTA/FAPESP Program was created in this context and it has been a successful initiative to promote studies on biodiversity and conservation in Brazil. The BIOTA/Araçá is an interdisciplinary project that provided a detailed evaluation of the biodiversity of Araçá Bay, a coastal seascape located on the North coast of the state of São Paulo, Southeast Brazil. The bay encompasses multiple habitats, such as beaches, mangroves, rocky shores, and a tidal flat, and provides important ecosystem services. Unfortunately, the bay is the subject of complex social-environmental conflicts that oppose economic, social, and environmental demands (i.e., the expansion of neighboring harbor activities vs. small-scale artisanal fisheries and protection of biodiversity). The present study presents a survey of the benthic species occurring in the different habitats of Araçá Bay, including data obtained during the BIOTA/Araçá project and previous assessments of the area. The benthic species play an important role in marine environments and studying the diversity of these organisms that live associated with the bottom is indispensable for comprehending the environment’s functioning. The macrofauna, meiofauna, and microorganisms associated with soft and hard bottom were listed, and additional information, such as the habitat and geographical distribution, were provided for each species. The checklist includes 826 species, almost 70% recorded during the BIOTA/Araçá project. The most speciose taxa were the annelids (225 spp.), mollusks (194 spp.), and crustaceans (177 spp.). Seven benthic species are endemic to Araçá Bay, 14 are considered threatened, and seven are economically exploited. Furthermore, the bay is the type locality of many taxa, and 11 new benthic species were described based on specimens sampled during the project. This project shows the importance of Araçá Bay as a unique biologically rich environment and highlights the need for conservation efforts in light of the current threats.

The Brazilian Continental Margin hosts several deep seafloor landscapes. However, this deep margin is still poorly studied and monitored, compared to coastal and continental shelf areas, historically limited to areas of particular economic interest. Some studies financed by the Brazilian oil and gas company have been conducted off Southeast (SE) Brazil (Espírito Santo and Campos Basins) as part of the environmental licensing process for resource exploration. Similar results showed that annelid polychaetes dominated on the continental shelf and upper slope. Within a wide bathymetric range, Capitellidae species belonging to three different genera represented new records for Brazil: Mastobranchus Eisig, 1887, Peresiella Harmelin, 1968, and Polymastigos Green, 2002. Mastobranchus braziliensis sp. nov. was found in shallow waters (20–147m) of both Espírito Santo and Campos Basins; Peresiella megapapilata sp. nov. occurred from 21 to 446m of both Espírito Santo and Campos Basins; and Polymastigos profundus sp. nov. inhabited greater depths (990–1361m) of the Espírito Santo Basin only. Three new species are described and compared to other species of the respective genus, the diagnosis of some genera amended and the type material of Mastobranchus loii Gallardo, 1968 redescribed. Although the three genera have the same number of thoracic chaetigers, they present several morphological differences, and the current effort being made is to “translate” those differences into characters to be included on the generic diagnosis of each genus. Additionally, two new morphological characters were proposed for the family, the shape of thoracic chaetigers and depth of intersegmental groove.

The genus Leiocapitella was described as having a wide variation on the number of thoracic chaetigers (13–17); however, this variation was added to the diagnosis of the genus based on undescribed species. A shortening in the range of variation of thoracic chaetigers is proposed until a re-examination of these species and a formal description be made. Currently, there are five valid species and a single species has been previously recorded in Brazil. The aim of this study was to investigate the diversity of this genus occurring in the Southeast Brazil. A new species has been found in samples collected on subtidal areas, Leiocapitella sensibilis sp. nov., and it is described and compared to other species of the genus. Leiocapitella atlantica Hartman, 1965 is redescribed after examination of the type material.

Polychaetes are common in coastal and estuarine environments worldwide and constitute one of the most complex groups of marine invertebrates. The morpho-physiology of the female reproductive system (FRS) can be understood by using histological tools to describe reproductive cycle and gametogenesis paths and, among other purposes, aiming to identify and differentiate polychaete species. However, this histology-based approach is rarely combined with molecular tools, which is known to accurately delimitate species. In the same way, the description and understanding of oogenesis and vitellogenesis paths within polychaetes are lacking for most families, narrowing the range of its utility. Therefore, the present study aims to describe the oogenesis in three polychaete species common and abundant on the South American Atlantic coast (Laeonereis culveri, Scolelepis goodbodyi and Capitella biota) and investigate the utility of reproductive features and gametogenesis as a relevant associate knowledge to discriminate species, particularly useful for putative cryptic species, integrated with morphological and molecular data. In a first attempt, the results obtained herein allow the authors to describe two new subtypes of oogenesis, dividing it in extraovarian oogenesis type I and II and intraovarian type I and II. The results also demonstrate that the following histological characters of the FRS can be relevant for the separation of related species: a) oogenesis type, b) occurrence or absence of a true ovary, c) ovary tissue organization, d) type of accessory cells present, and e) oocyte morphology. Additionally, these histological features of FRS, when compared with correlated species studied under this scope, converge with the genetic data. The analysis of cytochrome oxidase I (COI) barcode sequences differentiates between North and South American Atlantic populations of L. culveri (16.78% genetic distance), while in S. goodbodyi and C. biota it discriminates them from their congeneric species. These results highlight the importance of multi-tool approach and shows that both FRS histology and histo-physiology, and DNA barcoding can be used to identify and discriminate cryptic species, which is usually not possible when using morphological characters. Besides, these characters may also be useful in differentiating related species, and/or geographically distinct populations among polychaetes.

Capitellids of the genus Scyphoproctus are most readily identified by the distinctive pygidial region, generally consisting of a number of segments fused with the pygidium, forming a weakly or well-developed anal plaque. To date, there are 17 valid species, however, only one species has been previously recorded in Brazil. The aim of this study was to investigate the diversity of the genus occurring along the Northeast and Southeast coasts and sublittoral areas of Brazil. Three new species have been found in samples collected in a variety of habitats and depths, Scyphoproctus paivai sp. nov., S. profundus sp. nov., and S. robustus sp. nov. The new species are herein described and compared to other species of the genus and type material of two additional species are re-described, Scyphoproctus oculatus Reish, 1959 and S. pseudoarmatus (Silva 1965). The genus Heteromastides Augener, 1914 is herein relocated in Scyphoproctus Gravier, 1904 and the previous species Heteromastides platyproctus Pillai, 1961 (junior homonym) renamed as Scyphoproctus telesphorei n. nov. after the species author Telesphore Gottfried Pillai, because there is already a species named Scyphoproctus platyproctus Jones, 1961 (senior homonym). A taxonomic key of the valid and new species is also given.

The sibling species of Capitella capitata are globally known for their tolerance to disturbed habitats and the C. capitata complex is often used as an ecological indicator. A recent re-description proposed that C. capitata, originally described in Greenland is restricted to the Artic and Subarctic regions. Given their ecological relevance, we conducted a morphological and molecular analyses based on mtDNA sequences to investigate the diversity and distribution of the C. capitata complex along the Brazilian coast. Our morphological and molecular data were congruent and revealed the existence of four new species distinct from C. capitata, collected from the type locality. This study is the first characterization of the biodiversity and distribution of Capitella species made along the Brazilian coast and yielded a set of morphological characters corroborated by the mtDNA sequences for species identification. Our results increase the biodiversity of the genus along the Brazilian coast by describing four new species (Capitella aracaensis sp. n., Capitella biota sp. n., Capitella neoaciculata sp. n. and Capitella nonatoi sp. n.). One species was collected from only one sampling site, while the others are distributed along the coast.