Rhodoliths and Rhodolith Beds in the Rock Record

Aguirre, Julio; Braga, Juan C.; Bassi, Davide

doi:10.1007/978-3-319-29315-8_5

Cited by 54 publications

(52 citation statements)

References 138 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…) suggests background low‐moderate energy conditions, good oxygenation, low sedimentation rates and low turbidity enabling suitable light penetration; the assemblage of melobesioids and lithophylloids (Fig. D to F) suggests depths in the order of several tens of metres (Aguirre et al ., , ). Moreover, the characteristic macroinvertebrate species in this facies (Table ; Fig.…”

Section: Description Of Faciesmentioning

confidence: 99%

High‐frequency cycles of brachiopod shell beds on subaqueous delta‐scale clinoforms (early Pliocene, south‐east Spain)

García‐Ramos

Zuschin

2019

Sedimentology

View full text Add to dashboard Cite

During the early Pliocene, subaqueous delta-scale clinoforms developed in the Aguilas Basin, in a mixed temperate carbonate-siliciclastic system. The facies distribution is consistent with the infralittoral prograding wedge model. Stacking patterns and bounding surfaces indicate that the clinoforms formed during the highstand and falling sea-level stages of a high rank cycle. Twenty-two prograding clinothems were recognized over a distance of ≥1 km. Biostratigraphic data indicate a time span shorter than 700 kyr for the whole unit (MPl3 biozone of the Mediterranean Pliocene). Cyclic skeletal concentrations and occasional biostromes of suspension feeders (terebratulid brachiopods, modiolid bivalves and adeoniform bryozoan colonies), slightly evolved glauconite and occasional Glossifungites ichnofacies formed on the clinoforms during high-frequency pulses of relative sea-level rise. During such stages, increased accommodation space in the topsets of the clinoforms caused a strong reduction of terrigenous input into the foresets and bottomsets. This provided favourable conditions for the development of these suspension feeder palaeocommunities. During stillstand stages, however, reduced accommodation space in the topsets eventually resumed progradation in the foresets. There, the abundance of Ditrupa tubes indicates frequent siltation events that extirpated the terebratulid populations and other epifaunal suspension feeders in the foreset and bottomset subenvironments. The occurrence of shell beds on the clinoforms suggests that this case study represents lower progradation rates than standard examples where shell beds bound the clinobedded units at their base and top only. Importantly, the distributions of biofacies and ichnoassemblage associations contribute significantly to the understanding of the effects of relative sea-level fluctuations on the evolution of subaqueous delta-scale clinoform systems.

show abstract

Section: Description Of Faciesmentioning

confidence: 99%

High‐frequency cycles of brachiopod shell beds on subaqueous delta‐scale clinoforms (early Pliocene, south‐east Spain)

García‐Ramos

Zuschin

2019

Sedimentology

View full text Add to dashboard Cite

show abstract

“…Rhodoliths are incrusting, non-articulate aggregates of calcareous algae that usually occur in shallow waters, providing hard substrate for other organisms (Foster et al, 2007;. These algae retain calcium carbonate, and provide important information on paleoclimatic and paleoenvironmental conditions in a particular area (Amado-Filho & Pereira-Filho, 2012;Aguirre, Braga, & Bassi, 2017). Rhodolith banks are recorded from several regions in the world, mainly in the Gulf of California, in the Caribbean, along the Atlantic coast of Canada, in Great Britain, Norway, Japan, and Australia (Foster, 2001;Amado-Filho & Pereira-Filho, 2012).…”

mentioning

confidence: 99%

Is tourism affecting polychaete assemblages associated with rhodolith beds in Northeastern Brazil?

Costa

Silva²,

Silva

et al. 2019

RBT

View full text Add to dashboard Cite

ABSTRACT. Introduction: Rhodoliths are biogenic structures distributed worldwide, formed by several types of calcareous algae. They may host a great diversity of marine invertebrates, among which polychaetes are conspicuous and diversified representatives. Rhodolith beds are notwithstanding vulnerable to several human activities (e.g. exploitation of commercial species associated with rhodoliths, petroleum exploration, fishing activities, effluent discharges, and tourism), which may compromise that diversity. Tourism is presently increasing its impact on rhodolith beds. Global warming and ocean acidification are also determinant factors in faunal change. Objective: to analyse the polychaete assemblages associated with rhodolith beds subject to different intensities of touristic pressure at Seixas Beach (NE Brazil), where tourism is gradually increasing over time. Methods: Effects were evaluated at two depths, 1.5 m and 4.0 m. Sampling was done every two months during 2015, encompassing the two marked seasons of the year in the region (rainy and dry). Quadrats of 15 x 15 cm were placed in each depth during sampling. All rhodoliths present within the quadrat were collected (usually four to five rhodoliths). Our hypothesis was that the deeper depth and the samples from the dry season months would be increasingly subject to the impact of tourism. Results: Overall, 49 species were found (from 21 different families), and a total of 733 individuals were collected. The most abundant species was Eunice wasinensis (280 individuals, 38.2% of total abundance). The species Eurythoe complanata, Eunice biannulata, E. wasinensis, Lysidice ninetta, Oxydromus pugettensis and Ceratonereis (Ceratonereis) singularis appeared in all months. The study detected a tendency for higher diversity to occur at the depth of 1.5 m for all indices, but only the Shannon-Wiener values were significantly higher there (p < 0.05). No clear differences were found regarding months or season. Conclusions: These results suggest that a higher potential pressure due to tourism may occur at 4.0 m due to more intense craft shipping activities (traffic of catamaran boats transporting tourists to and from the reefs) in that area.

show abstract

“…Spheroidal to ellipsoidal forms indicate moderate‐ to high‐energy settings as hydrodynamics foster overturning (Aguirre et al . ). However, Lund et al .…”

Section: Palaeobiology and Palaeoecologymentioning

confidence: 97%

“…8), whatever their origin and components. Spheroidal to ellipsoidal forms indicate moderate-to high-energy settings as hydrodynamics foster overturning (Aguirre et al 2017). However, Lund et al (2000) show that there are no clear relationships between hydrodynamics and morphology because density and gravity point of the macroid has to be taken into account.…”

Section: Palaeobiology and Palaeoecologymentioning

confidence: 99%

From rolling stones to rolling reefs: a Devonian example of highly diverse macroids

Denayer

2018

LET

View full text Add to dashboard Cite

The upper carbonate member of the Aisemont Formation (Upper Frasnian, Belgium) yielded a surprisingly diverse assemblage of macroids varying in size, shape and composition, from simplest microbial oncoid to complex, polytaxic circumrotatory macroid. A descriptive classification combining composition and geometry of macroids is proposed. It suits for sedimentological and palaeobiological analyses. Five categories forming a continuum are distinguished as follows: (1) simple oncoids, consisting of microbial coating of various nuclei; (2) composite oncoids, involving several encrusting taxa and microbes‐induced precipitates; (3) simple circumrotatory macroids, constructed by one or few different organisms and forming free‐rolling particle; (4) polytaxic circumrotatory macroids, constructed by diverse organisms, usually in sequential coating and form free‐rolling object; and, (5) polytaxic domed macroids, polytaxic assemblage of encrusting organism forming domed or columnar anchored bioconstructions. The dominant (in number and volume) encrusting organisms are the tabulate corals and stromatoporoids that both possessed the ability to attach to any hard substrate. Microbes also contributed to the formation of macroids although the volume they occupy is relatively limited. Skeletal invertebrates likely grew during the good season when environmental conditions were suitable for the growth, then partly or totally died and was colonized by microbes during the bad season. The surface of the macroid (after rolling or not) was subsequently re‐coated with skeletal organisms when suitable conditions re‐established. Final burial of the macroid occurred during the good season as their outermost surface is rarely coated with microbes. Geopetal sediment filling of cavities displays various directions indicating the rolling of the objects during their formation. Periodical rolling or tilting may be related to seasonal storms and the resulting assemblage formed genuine rolling reefs of crucial importance for birth palaeoecological and sedimentological analysis.

show abstract

Rhodoliths and Rhodolith Beds in the Rock Record

Cited by 54 publications

References 138 publications

High‐frequency cycles of brachiopod shell beds on subaqueous delta‐scale clinoforms (early Pliocene, south‐east Spain)

High‐frequency cycles of brachiopod shell beds on subaqueous delta‐scale clinoforms (early Pliocene, south‐east Spain)

Is tourism affecting polychaete assemblages associated with rhodolith beds in Northeastern Brazil?

From rolling stones to rolling reefs: a Devonian example of highly diverse macroids

Contact Info

Product

Resources

About