No abstract

Lepraliomorph-grade ascophorans are the dominant group of bryozoans in most modern faunas. Here we describe five new species (Parasmittina alba sp. nov., Microporella proxima sp. nov., Reteporella antennata sp. nov., Stephanollona robustaspinosa sp. nov. and Turritigera buski sp. nov.) and record an additional five lepraliomorph species [Watersipora subovoidea (d'Orbigny, 1852), Schizoporella errata (Waters, 1878), Arthropoma cecilii (Audouin, 1826), Celleporina diota (Marcus, 1938) and Reteporellina evelinae Marcus, 1955] from the coastal waters off Rio de Janeiro State in Brazil. This increases the biodiversity of the bryozoan fauna from Brazil, and the number of species known from Rio de Janeiro State now totals 79.

In major modern reef regions, either in the Indo-Pacific or the Caribbean, scleractinian corals are described as the main reef framework builders, often associated with crustose coralline algae. We used underwater cores to investigate Late Holocene reef growth and characterise the main framework builders in the Abrolhos Shelf, the largest and richest modern tropical reef complex in the South Western Atlantic, a scientifically underexplored reef province. Rather than a typical coralgal reef, our results show a complex framework building system dominated by bryozoans. Bryozoans were major components in all cores and age intervals (2,000 yrs BP), accounting for up to 44% of the reef framework, while crustose coralline algae and coral accounted for less than 28 and 23%, respectively. Reef accretion rates varied from 2.7 to 0.9 mm yr−1, which are similar to typical coralgal reefs. Bryozoan functional groups encompassed 20 taxa and Celleporaria atlantica (Busk, 1884) dominated the framework at all cores. While the prevalent mesotrophic conditions may have driven suspension-feeders’ dominance over photoautotrophs and mixotrophs, we propose that a combination of historical factors with the low storm-disturbance regime of the tropical South Atlantic also contributed to the region’s low diversity, and underlies the unique mushroom shape of the Abrolhos pinnacles.

The abundance of reef builders, non-builders and the calcium carbonate produced by communities established in Calcification Accretion Units (CAUs) were determined in three Abrolhos Bank shallow reefs during the period from 2012 to 2014. In addition, the seawater temperature, the irradiance, and the amount and composition of the sediments were determined. The inner and outer reef arcs were compared. CAUs located on the inner reef shelf were under the influence of terrigenous sediments. On the outer reefs, the sediments were composed primarily of marine biogenic carbonates. The mean carbonate production in shallow reefs of Abrolhos was 579 ± 98 g m-2 y-1. The builder community was dominated by crustose coralline algae, while the non-builder community was dominated by turf. A marine heat wave was detected during the summer of 2013–2014, and the number of consecutive days with a temperature above or below the summer mean was positively correlated with the turf cover increase. The mean carbonate production of the shallow reefs of Abrolhos Bank was greater than the estimated carbonate production measured for artificial structures on several other shallow reefs of the world. The calcimass was higher than the non-calcareous mass, suggesting that the Abrolhos reefs are still in a positive carbonate production balance. Given that marine heat waves produce an increase of turf cover on the shallow reefs of the Abrolhos, a decrease in the cover represented by reef builders and shifting carbonate production are expected in the near future.

This is the first of two comprehensive taxonomic works on the early Miocene (ca. 23–20 Ma) bryozoan fauna associated with coral reefs from the Siamaná Formation, in the remote region of Cocinetas Basin in the La Guajira Peninsula, northern Colombia, southern Caribbean. Fifteen bryozoan species in 11 families are described, comprising two cyclostomes and 13 cheilostomes. Two cheilostome genera and seven species are new: Antropora guajirensis n. sp., Calpensia caribensis n. sp., Atoichos magnus n. gen. n. sp., Gymnophorella hadra n. gen. n. sp., Cribrilaria multicostata n. sp., Cribrilaria nixor n. sp., and Figularia bragai n. sp. Eight species are identified only at genus level and remain in open nomenclature. Of the species found, 27% have erect colonies and 73% encrusting colonies. Both types contributed to the reef framework and produced sediment. The observed bryozoan diversity was higher in the barrier reefs than in the lagoonal patch reefs. UUID: http://zoobank.org/5c8468ef-31b0-4e7e-ba93-60a2e2f30b76.