Cristiane Xerez Barroso

Mollusks from two estuarine areas in Ceará state, northeastern Brazil, with new state records for four species

We analyzed qualitatively the malacofauna found in the tidal zones of Banco dos Cajuais and Ilha Grande estuarine complex, both in Ceara State, northeastern Brazil. Qualitative data on the malacofauna from Banco dos Cajuais and the Ilha Grande estuarine complex were obtained by systematic sampling in 2008 and 2009 during field activities for the “Migratory Shorebirds Conservation and Shrimp Farming in Northeast Brazil” project. Twenty-two species of mollusks (13 bivalves and 9 gastropods) were found in Banco dos Cajuais, and 25 species (18 bivalves and 7 gastropods) were found in the Ilha Grande estuarine complex. Four species, Lucina muricata (Spengler, 1798), Tagelus divisus (Lightfoot, 1786), Crassinella martinicensis (d’Orbigny, 1853), and Periploma ovata Kuroda and Horikoshi, 1958 were recorded from Ceara for the first time.

Spawning and intra-capsular development of Neritina zebra (Bruguière, 1792) (Mollusca: Gastropoda: Neritidae) under laboratory conditions

Abstract The gastropod Neritina zebra is distributed in Suriname and along the coast of Brazil, where it lives on muddy bottoms of brackish water environments. The objectives of this study were to describe the spawning of N. zebra and to investigate its embryonic and larval development under laboratory conditions. The egg capsules are oval. The surface of the capsule in contact with the substratum is flat, while the opposite surface is convex and covered by sand grains. One end has a small suture. A thin membrane surrounds the eggs. Inside the capsules, the developing embryos and larvae are surrounded by fluid (albuminous liquid). N. zebra has mixed development. It was not possible to observe settlement and metamorphosis of veligers in the laboratory due to their death a few days after hatching. In the 2007 experiment, the capsules opened, releasing veligers, after 21 days. In 2008, the capsules opened after 26 or 27 days after the salinity was reduced from 15 to 10 ppt. N. zebra may be amphidromous, as are others of the same genus which inhabit environments with a strong freshwater influence and have planktotrophic larvae.

Holocene invertebrates from the Rocas Atoll: A contribution for the ecological history of South Atlantic islands

The South Atlantic Ocean is the youngest of the world’s oceans and one of the most important biodiversity hotspots; however, there is a lack of scientific knowledge about its ecological history. Here, we present the first results of a fossil invertebrate survey from the Rocas Atoll. By using radiometric dating (C) and a survey of fossilized benthic invertebrates on this atoll, we provide new paleobiogeographic and paleoceanographic information. The results suggest eight taxa (five mollusks, two corals, and one decapod). Dates ranged from 3449 ± 790 y BP to 3033 ± 620 y BP. The data represent new invertebrate records for the middle Holocene in this atoll, and evidence of sea-level changes in this period. Considering that the Rocas Atoll is one of the newest marine atolls in the world, these results suggest recent colonization by species from the Southwestern Atlantic Coast and Fernando de Noronha Archipelago.

Marine benthic communities affected by the Doce River (southwestern Atlantic): Baseline before a mining disaster

Prior to Brazils worst environmental disaster, caused by a mining dam collapse, we had carried out a study of the marine benthic macrofauna (11-51 m depth) under the influence of the Doce River. Our results showed significant diversity, in which mollusks, polychaetes, and crustaceans had the highest frequency, density, and abundance, represented by 162 families in summer and 173 in winter. Our results suggested that richness, abundance, and diversity increase with distance from the coast. Furthermore, with increasing distance from the coast and river mouth, in addition to increasing depth, there was a differentiation in composition and abundance. Multivariate analyses showed depth, carbonate, and organic matter as important factors that explain variations in composition and diversity across the continental shelf. The results could provide an invaluable baseline for measuring the effects on shallow and mesophotic communities of one of the largest tailings dam failures worldwide.

Septibranchia (Mollusca: Bivalvia) from the North and Northeast Coasts of Brazil

BackgroundSeptibranchia comprises groups of bivalves that have developed a series of anatomical and conchological modifications toward a carnivorous and/or saprophagic lifestyle. The present study aims to identify the species of the families Poromyidae, Cuspidariidae and Verticordiidae found off the northern and north-eastern coasts of Brazil, reducing the gaps in the geographic distribution and adding new morphological data of the analysed shells.ResultsSix genera and eight species were found in the 54 examined lots: Cardiomya cleryana, Cardiomya ornatissima, Cardiomya perrostrata, Cuspidaria sp., Plectodon braziliensis, Myonera aff. paucistriata, Poromya cf. granulata and Trigonulina ornata. The present study adds new conchological and morphometric characteristics to descriptions of species, redulces the gap in the distribution of Plectodon braziliensis in the Southwestern Atlantic, and extends the northern distribution limit of P. braziliensis and C. cleryana with new records for off the north-north-east coast of Brazil.ConclusionsBy adding new morphological and morphometric data of the shells, the present study may help in the taxonomy of these septibranch species. New collections in the region will probably lead to the discovery of new records of Septibranchia.

An extended geographical distribution of Donax gemmula Morrison, 1971 (Bivalvia: Donacidae): new record from the Brazilian Northeastern coast

This study provides the first record of Donax gemmula Morrison, 1971 (Bivalvia: Donacidae) from the Ceara State, Northeast Brazil; up to now it was only known from the Southeastern and Southern Brazilian coast. Shells larger than ~2 mm in length of this species can be distinguished from those of D. striatus Linnaeus, 1767. Both species were collected in the same beaches: Banco dos Cajuais and Pecem. The occurrence of D. gemmula remains unnoticed for others States of the Northeast Brazil, and so we suggest two possible explanations for this finding from Ceara State: i) a recent introduction (e.g., by ballast water); or ii) this species has a continuous distribution along the Brazilian coast (Ceara to Rio Grande do Sul), being not recorded until now because this is not easily collected (the animals are small and bottom samples need to be sieved to obtain them) and may be confused with young specimens of other species of Donax , such as D. striatus .