Bryozoans are Major Modern Builders of South Atlantic Oddly Shaped Reefs

Bastos, Alex Cardoso; Moura, Rodrigo L.; Moraes, Fernando C.; Vieira, Laura S.; Braga, Juan C.; Ramalho, Laís V.; Amado‐Filho, Gilberto M.; Magdalena, Ulises Rodrigo; Webster, Jody M.

doi:10.1038/s41598-018-27961-6

Cited by 47 publications

(27 citation statements)

References 41 publications

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“…In the present work, we characterized the RBs and surrounding biogenic formations as bryozoans and reefs covered by CCA. Bryozoans were also found previously as the dominant group building the Abrolhos Bank pinnacles in Brazil [62]. Our study identified bryozoans as the main component between depths of 35 and 50 m on the DRS.…”

Section: Discussionsupporting

confidence: 83%

Structure of Rhodolith Beds and Surrounding Habitats at the Doce River Shelf (Brazil)

et al. 2020

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The world's largest rhodolith beds have been reported from the Brazilian continental shelf. Highly biodiverse beds are located in Southeast Brazil, but ecological aspects of these beds remain unknown. Despite their ecological importance, rhodolith beds (RBs) have recently been subjected to a severe threat, when more than 35 million cubic meters of mining residues slid down a mountainside on 5 November 2015, after a collapse of a gigantic dam upstream (the Mariana disaster), causing a huge impact on the Doce River. Our aim is to assess rhodolith beds and adjacent coralline formations on the Doce River Shelf (DRS) after the dam collapse. This paper describes the distribution, abundance, vitality, size and shape, as well as unmapped bryozoan rich sediment formations in this area, serving as baseline knowledge for environmental monitoring. Four distinct biogenic sea bottom habitats (bryozoan bottoms, rhodolith beds, carbonate concretions, and reefs) were recognized at different depth ranges with distribution indicated to be mostly related to the local sedimentary regime. Mud sediments dominated the seafloor up to 35 m depth. On the mid shelf, bryozoan bottoms were recorded from 35 to 45 m depth. Crustose coralline algae (CCA) occurring as rhodoliths and carbonate concretions extend over 1953 km 2 in the mid and outer shelf. Rhodolith beds predominate in these areas, totaling 1521 km 2 of sea bottom and were more abundant at depths between 45 and 65 m, occupying an extensive area south of the Doce River mouth. Northward, rhodolith beds are less abundant or absent likely due to the long-term deposition of fine sediments in this region. Carbonate concretions and reefs covered by CCA occupy sparse areas on the outer shelf (65-105 m depth). Differences in rhodolith features recorded, including coverage, density and size, may be related to the Doce River sedimentation and related factors (e.g., hydrodynamics, depth, and light). However, since there are no previous detailed studies on RBs along the DRS, we could not assess the impact of sedimentation of dam wastes on RBs' abundance and density. In any case, these are valuable results for the further monitoring of long-term effects. Considering that the growth of these rhodoliths is relatively slow, and that they are affected by the sedimentation from the Doce River, the implementation of a management and conservation plan for this area is necessary in order to preserve this ecosystem.

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Section: Discussionsupporting

confidence: 83%

Structure of Rhodolith Beds and Surrounding Habitats at the Doce River Shelf (Brazil)

et al. 2020

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“…The Abrolhos Bank (16°40′–19°40′ S, 39°10′–37°20′ W) comprises a 40,000 km 2 benthic mosaic of reefs, rhodolith beds and unconsolidated sediments, encompassing the largest and richest reefs within the South Atlantic ( Moura et al, 2013 ). The reefs are remarkable for their mushroom-shaped pinnacles with flat tops, which result in strong habitat variation at relatively small spatial scales (pinnacles’ walls and tops) ( Bastos et al, 2008 ). Pinnacles are dominated by massive and encrusting corals, reaching up to 30% of the benthic cover ( Francini-Filho et al, 2013 ).…”

Section: Methodsmentioning

confidence: 99%

Long-term effects of competition and environmental drivers on the growth of the endangered coral Mussismilia braziliensis (Verril, 1867)

Ribeiro

Sá

Fistarol

et al. 2018

PeerJ

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Most coral reefs have recently experienced acute changes in benthic community structure, generally involving dominance shifts from slow-growing hard corals to fast-growing benthic invertebrates and fleshy photosynthesizers. Besides overfishing, increased nutrification and sedimentation are important drivers of this process, which is well documented at landscape scales in the Caribbean and in the Indo-Pacific. However, small-scale processes that occur at the level of individual organisms remain poorly explored. In addition, the generality of coral reef decline models still needs to be verified on the vast realm of turbid-zone reefs. Here, we documented the outcome of interactions between an endangered Brazilian-endemic coral (Mussismilia braziliensis) and its most abundant contacting organisms (turf, cyanobacteria, corals, crustose coralline algae and foliose macroalgae). Our study was based on a long (2006–2016) series of high resolution data (fixed photoquadrats) acquired along a cross-shelf gradient that includes coastal unprotected reefs and offshore protected sites. The study region (Abrolhos Bank) comprises the largest and richest coralline complex in the South Atlantic, and a foremost example of a turbid-zone reef system with low diversity and expressive coral cover. Coral growth was significantly different between reefs. Coral-algae contacts predominated inshore, while cyanobacteria and turf contacts dominated offshore. An overall trend in positive coral growth was detected from 2009 onward in the inshore reef, whereas retraction in live coral tissue was observed offshore during this period. Turbidity (+) and cyanobacteria (−) were the best predictors of coral growth. Complimentary incubation experiments, in which treatments of Symbiodinium spp. from M. braziliensis colonies were subjected to cyanobacterial exudates, showed a negative effect of the exudate on the symbionts, demonstrating that cyanobacteria play an important role in coral tissue necrosis. Negative effects of cyanobacteria on living coral tissue may remain undetected from percent cover estimates gathered at larger spatial scales, as these ephemeral organisms tend to be rapidly replaced by longer-living macroalgae, or complex turf-like consortia. The cross-shelf trend of decreasing turbidity and macroalgae abundance suggests either a direct positive effect of turbidity on coral growth, or an indirect effect related to the higher inshore cover of foliose macroalgae, constraining cyanobacterial abundance. It is unclear whether the higher inshore macroalgal abundance (10–20% of reef cover) is a stable phase related to a long-standing high turbidity background, or a contemporary response to anthropogenic stress. Our results challenge the idea that high macroalgal cover is always associated with compromised coral health, as the baselines for turbid zone reefs may derive sharply from those of coral-dominated reefs that dwell under oligotrophic conditions.

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“…Where they occur, these extensive algal build‐ups constitute an important component of the MEs, with the coalescence of rhodoliths having been hypothesized as a possible mechanism for the formation of carbonate reefs (Amado‐Filho et al., ). In fact, many Brazilian biogenic reefs are primarily formed by the growth of calcareous red algae, bryozoans, milleporids and scleractinian corals (Bastos et al., ; Leão et al., ).…”

Section: South Atlantic Mesophotic Ecosystemsmentioning

confidence: 99%

Mesophotic ecosystems: Distribution, impacts and conservation in the South Atlantic

Soares

Tavares

Carneiro

2018

Diversity and Distributions

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Aim: This study reviews recent research on the South Atlantic Mesophotic ecosystems (MEs) and the pressures threatening them, and offers suggestions for their management and conservation. Location:The South Atlantic Ocean. Methods:A comprehensive compilation of the scientific literature was performed to examine the distribution, human impacts and conservation status of the South Atlantic MEs. Results: Our review indicated that the South Atlantic Ocean (SAO) is one of the majorMEs areas in the world's oceans. The South Atlantic MEs are composed of a mosaic of distinct seascapes, mainly rhodolith beds, mesophotic reefs (i.e., rocky and biogenic) and marine animal forests (e.g., sponge aggregations, octocoral and black coral forests) that occur along the East South American and West African coasts, seamounts and oceanic islands. Throughout the SAO, the distinct seascapes of MEs are usually formed on the middle and outer continental shelves, shelf-edge, seamounts, submarine canyons, incised valleys and paleochannels, reef structures and insular shelves. We highlighted sea temperature anomalies, ocean acidification, extreme floods and droughts, fisheries, invasive species, marine debris, mining, and oil and gas exploitation as major threats to these ecosystems. Main conclusions:Given the threats to the South Atlantic MEs, growing human pressures may degrade these ecosystems in the next years and undermine their unique biodiversity as well as their potential to provide connectivity between regions and depths. Our review revealed the existence of some extensive and unprotected formations, which urgently demand in-depth investigations and conservation action. K E Y W O R D S climate change, coral reef, deep-sea refugia, marine biogeography, marine conservation, rhodolith bed 1 | INTRODUC TI ON Developments in the marine sciences, especially in terms of methodology and equipment, have allowed the exploration of progressively deeper oceanic zones, providing a more detailed picture of the hidden biodiversity in mesophotic ecosystems (MEs; Loya, Eyal, Treibitz, Lesser, & Appeldoorn, 2016). These ecosystems are characterized by the presence of light-dependent corals and associated species (e.g.,

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Bryozoans are Major Modern Builders of South Atlantic Oddly Shaped Reefs

Cited by 47 publications

References 41 publications

Structure of Rhodolith Beds and Surrounding Habitats at the Doce River Shelf (Brazil)

Structure of Rhodolith Beds and Surrounding Habitats at the Doce River Shelf (Brazil)

Long-term effects of competition and environmental drivers on the growth of the endangered coral Mussismilia braziliensis (Verril, 1867)

Mesophotic ecosystems: Distribution, impacts and conservation in the South Atlantic

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