Natural History of Rhodolith/Maërl Beds: Their Role in Near-Shore Biodiversity and Management

Riosmena‐Rodríguez, Rafael

doi:10.1007/978-3-319-29315-8_1

Cited by 42 publications

(53 citation statements)

References 88 publications

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“…Ecological factors required for the healthy development of rhodolith beds in recent oceans are well-oxygenated bottom conditions, low sedimentation rates, low content of suspended particles, and moderate water energy ( [4,74] and references therein). Except where rhodoliths were transported from shallower settings, rhodoliths in the rest of the study areas formed in oxygenated conditions, as shown by the prolific abundance of accompanying faunas, such as sea urchins, corals, LBF, bryozoans, and mollusks.…”

Section: Rhodolith Beds During the Eocenementioning

confidence: 99%

Middle Eocene Rhodoliths from Tropical and Mid-Latitude Regions

et al. 2020

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During the greenhouse conditions prevailing in the early–middle Eocene, larger benthic foraminifers (LBF) spread out on carbonate platforms worldwide while rhodolith beds were scarcely represented. This reduction in rhodolith beds coincided with a relative decrease in coralline algal diversity and with a drastic decline of coral reef abundance. Middle Eocene rhodoliths from two tropical (San Jacinto Fold Belt in northern Colombia and Bahoruco Peninsula in the Dominican Republic) and two mid-latitude (Salinas Menores Ravine and Sierra del Zacatín in Southern Spain) localities were studied. Rhodolith rudstones in the tropical areas accumulated on relatively deep (several tens of meters) platform environments and were also redeposited in deeper settings downslope. In Salinas Menores, rhodoliths are dispersed in planktic foraminifer-rich marls. Miliolids are common in the infilling of constructional voids in these rhodoliths, indicating that they originally grew in shallow-water inner-shelf settings and afterwards they were transported to deeper environments. In Sierra del Zacatín, rhodoliths are scarce and coralline algae mainly occur as crusts attached to and intergrowing with corals. Here, LBF dominated shallow-water carbonate platforms. In terms of taxonomic composition, coralline algae of the order Hapalidiales are the most abundant in the study areas, followed by Sporolithales. The order Corallinales is poorly represented except in Salinas Menores, where it is relatively abundant and diverse. The impact of high temperatures due to high levels of atmospheric CO2 during the Eocene and widespread oligotrophic conditions, which favored formation of LBF-rich lithofacies, might account for the low abundance of rhodolith beds at mid and high latitudes. In contrast, the more productive equatorial regions would have favored the formation of rhodolith beds.

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Section: Rhodolith Beds During the Eocenementioning

confidence: 99%

Middle Eocene Rhodoliths from Tropical and Mid-Latitude Regions

et al. 2020

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“…Mediterranean RBs are characterized by a higher CA biodiversity than NE Atlantic beds, which are usually monospecific/oligospecific, and mainly composed by Phymatolithon calcareum and Lithothamnion corallioides [ 53 , 65 ]. Moreover, RBs can be structured by a suite of combinations of rhodolith shapes and growth-forms [ 1 , 53 ], depending on the species, sedimentation, hydrodynamism, and seabed morphology [ 8 , 66 , 67 ], concurring to increase the RB complexity, which in turn influences the diversity and abundance of associated assemblages [ 3 , 19 , 68 ].…”

Section: Introductionmentioning

confidence: 99%

Distribution and Characterization of Deep Rhodolith Beds off the Campania coast (SW Italy, Mediterranean Sea)

Rendina

Kaleb

Caragnano

et al. 2020

Plants

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Rhodolith beds (RBs) are bioconstructions characterized by coralline algae, which provide habitat for several associated species. Mediterranean RBs are usually located in the mesophotic zone (below 40 m), and thus are frequently remote and unexplored. Recently, the importance and vulnerability of these habitats have been recognized by the European Community and more attention has been drawn to their investigation and conservation. This study reports the results of an extensive monitoring program, carried out within the Marine Strategy Framework Directive (2008/56/EC), in six sites off the Campania coast (Italy, Mediterranean Sea). New insights were given into the distribution, cover, vitality (i.e., live/dead rhodolith ratio), structural complexity, and coralline algae composition of RBs. Remotely operated vehicles (ROV) investigations allowed the description of several RBs, and the discovery of a RB with rhodolith cover >65% offshore the Capri Island. Only two sites (Secchitiello and Punta Campanella) showed a very low mean cover of live rhodoliths (<10%); hence, not being classifiable as RBs. The collected rhodoliths were mostly small pralines (~2 cm), spheroidal to ellipsoidal, with growth-forms ranging from encrusting/warty to fruticose/lumpy. Coralline algae identification revealed a high diversity within each bed, with a total of 13 identified taxa. The genus Lithothamnion dominated all sites, and Phymatolithon calcareum and Lithothamnion corallioides, protected by the Habitats Directive (92/43/EEC), were detected in all RBs.

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“…Calcifying red algae are key components of many marine ecosystems globally. One of their main values is substrate provision [1,2] via their formation of calcified structures. The Peyssonnelia species mineralise aragonite [3–5], whereas the coralline algae (Corallinales, Sporolithales and Hapalidiales) mineralise Mg-calcite within their cell walls [6–10].…”

Section: Introductionmentioning

confidence: 99%

Coralline algal calcification: A morphological and process-based understanding

et al. 2019

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Research purpose and findingsCoralline algae are key biological substrates of many carbonate systems globally. Their capacity to build enduring crusts that underpin the formation of tropical reefs, rhodolith beds and other benthic substrate is dependent on the formation of a calcified thallus. However, this important process of skeletal carbonate formation is not well understood. We undertook a study of cellular carbonate features to develop a model for calcification. We describe two types of cell wall calcification; 1) calcified primary cell wall (PCW) in the thin-walled elongate cells such as central medullary cells in articulated corallines and hypothallial cells in crustose coralline algae (CCA), 2) calcified secondary cell wall (SCW) with radial Mg-calcite crystals in thicker-walled rounded cortical cells of articulated corallines and perithallial cells of CCA. The distinctive banding found in many rhodoliths is the regular transition from PCW-only cells to SCW cells. Within the cell walls there can be bands of elevated Mg with Mg content of a few mol% higher than radial Mg-calcite (M-type), ranging up to dolomite composition (D-type).Model for calcificationWe propose the following three-step model for calcification. 1) A thin (< 0.5 μm) PCW forms and is filled with a mineralising fluid of organic compounds and seawater. Nanometer-scale Mg-calcite grains precipitate on the organic structures within the PCW. 2) Crystalline cellulose microfibrils (CMF) are extruded perpendicularly from the cellulose synthase complexes (CSC) in the plasmalemma to form the SCW. 3) The CMF soaks in the mineralising fluid as it extrudes and becomes calcified, retaining the perpendicular form, thus building the radial calcite. In Clathromorphum, SCW formation lags PCW creating a zone of weakness resulting in a split in the sub-surface crust. All calcification seems likely to be a bioinduced rather than controlled process. These findings are a substantial step forward in understanding how corallines calcify.

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Natural History of Rhodolith/Maërl Beds: Their Role in Near-Shore Biodiversity and Management

Cited by 42 publications

References 88 publications

Middle Eocene Rhodoliths from Tropical and Mid-Latitude Regions

Middle Eocene Rhodoliths from Tropical and Mid-Latitude Regions

Distribution and Characterization of Deep Rhodolith Beds off the Campania coast (SW Italy, Mediterranean Sea)

Coralline algal calcification: A morphological and process-based understanding

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