Rhodolith

About: Rhodolith is a research topic. Over the lifetime, 377 publications have been published within this topic receiving 11206 citations.

The Ecology of Coralline Algal Crusts: Convergent Patterns and Adaptative Strategies

Abstract: Although crustose coralline algae (Rhodophyta, Corallinaceae) are among the most abundant marine organisms to live on hard substratum within the photic zone, relatively little is known about their ecology at the species level. This is due in part to difficulties in identification; strong similarities in appearance exist among phylogenetically distant taxa. The study of such convergent morphological and anatomical properties of corallines provides insight into interpreting the adaptive value of some characters or the "strategies" (55) of some of these plants. Crustose corallines are nonarticulated calcareous red algae that commonly grow prostrate on hard substrata and as epibionts on other plants and animals. Although these algae are globally abundant (18, 109), until recently most coralline research has been taxonomic. Early ecological accounts were largely confined to distributional studies. In the 1960s and 1970s, interest in the ecology of corallines grew as problems with their taxonomy were resolved. The corallines were generally recognized to be abundant (26, 43, 44, 69, 71, 96) and geologically important (14, 18, 74). It was suggested that "once obstacles arising from taxonomic problems are generally overcome, it seems likely that the group will be included more often in ecological studies or may even become 'popular subjects' " (18). However,

Rhodoliths: between rocks and soft places

Abstract: Rhodoliths (maerl) are widely distributed in the worlds' oceans and have an excellent fossil record. Individuals are slow growing, may be long lived (>100 years), and are resilient to a variety of environmental disturbances. Their external morphology and internal growth bands are potential archives of environmental variation at scales of within years to tens of years. At high densities, these free-living non-geniculate coralline algae form rhodolith beds, communities of high diversity that can be severely impacted by resource extraction.

Crustose Coralline Algae: A Re-evaluation in the Geological Sciences

Abstract: The crustose coralline algae are well known in shallow tropical waters as reef frame-builders and sediment producers. Although their abundance at greater depths and in arctic waters has been previously recorded, this knowledge in recent decades has been largely ignored by geologists and marine scientists in general. Many erroneous or misleading ecological and paleoecological statements and conclusions have resulted, and we have endeavored to clarify matters through the citation of the older literature along with more recent ecological studies. A parallel tendency to “simplify” the taxonomic structure of crustose corallines has threatened to add considerable confusion to modern marine studies. We have discussed recent work on anatomy, reproduction, and taxonomy. These and classical data are summarized in the form of keys and an evolutionary tree, which are intended to provide the geologist and marine biologist with a working facility with the group. A number of quantitative ecological studies treating crustose corallines have appeared during the past decade; these results are discussed and possibilities for future ecological work indicated. The occurrence of rhodoliths (maerl, free corallines) and the factors controlling the development of these deposits are also noted.

Growth-forms in non-geniculate coralline red algae (Corallinales, Rhodophyta)

Abstract: Although differences in growth-form have been widely used in delimiting taxa of non-geniculate coralline red algae (Corallinales, Rhodophyta), there has been no consistent application of the more than 100 terms employed to describe the growth-forms present, and considerable confusion has resulted. This study of over 5000 populations of non-geniculate corallines from all parts of the world has shown that an intergrading network of growth-forms with 10 focal points is present: unconsolidated, encrusting, warty, lumpy, fruticose, discoid, layered, foliose, ribbon-like and arborescent. This focal point terminology can be used to describe any specimen or species of non-geniculate coralline in a consistent, easily interpretable manner. Details of the system are provided, the relationships of the system to past proposals are discussed, and the extent to which differences in growth-forms can be used as taxonomic characters in the non-geniculate Corallinales is reviewed.

Rhodolith bed diversity in the Gulf of California: the importance of rhodolith structure and consequences of disturbance

Abstract: Rhodolith beds, unattached coralline reefs, support a high diversity and abundance of marine species from both hard and soft benthos. We used surveys in multiple shallow (3-20 m) beds in the Gulf of California to (1) examine seasonal patterns in associated floral and faunal diversity and abundance, (2) compare differences in faunal associations between rhodolith beds and adjacent sedimentary habitats, (3) examine the importance of complexity of rhodolith structure to community structure, and (4) estimate the impact of anthropogenic disturbance on rhodoliths and associated species. 2. Macroalgal richness was seasonal, and beds supported higher richness in winter (to 36 species) than summer (6-7 species), primarily due to foliose red algae. Strong seasonal variation in the abundance of dominant cover organisms was due to a shift from macroalgae and mat-forming colonial invertebrate species to microalgae. 3. The community in a rhodolith bed of high-density thalli (El Coyote average 11000 thalli/ m 2 ) had higher richness (52 versus 30 species) and abundance of epibenthic and crypto- and in- faunal species compared with an adjacent sand community. Species diversity and abundance was particularly high for unique cryptofaunal organisms associated with rhodolith interstices. Cryptofauna reached average densities of 14.4 organisms/ cm 3 rhodolith, the majority of which were crustaceans, polychaetes and cnidarians along with rhodolith-specific chitons. 4. Results from sampling across a range of rhodolith morphs in the El Requeson bed (with lower average cryptofaunal densities of 2.3 organisms/ cm 3 ) revealed that the total organisms supported by a rhodolith significantly increased with both complexity (branching density) and space available (thallus volume). These data suggest that reducing the population size structure, structural complexity and cover of living rhodoliths could decrease species richness and abundance. 5. While disturbance is a natural feature of these free-living beds, increased anthropogenic disturbance from trawling, anchoring and changes in water quality can directly impact the bed community through substrate alteration. Commercial fishing threatens rhodolith beds in the Gulf of California by decreasing rhodolith size and increasing sedimentation and burial rates. In addition to