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The Nature of Crustose Coralline Algae and Their Interactions on Reefs
... The coralline algae also noticed on coral frame surfaces. This coralline is a good indicator since the presence of coralline algae might attract the coral spat to attach on the substrate and start metamorphosis (Brown et al., 2017;Littler & Littler, 2013;Villas et al., 2005). During the observation, it was found that this area has started to become a habitat for coral reef fish. ...
Coral transplantation is a widely used technique for restoring damaged reefs in order to restore coral
abundance, recruitment, and species diversity. However, its limited evidence to prove the impacts on coral reef
fish. In this study, the fish abundance was determined before and after a coral transplant project at Geluk island,
Terengganu. Prior to the study, branching coral from acropora formosa species were propagated and evaluated for
2 years. The experimental design included a mortality percent and the growth rate of coral fragment used.
Correspondingly, quantify the differences in reef fish diversity indices before and after the propagation. Overall,
the coral fragment survived at rate of 96%, and the growth rates of fragment ranged between 6.4 ± 0.6 cm/year to
9.5 ± 1.1 cm/year. Pomacentridae was determined to be dominant family for coral reef fish, and the fish species
increased in term of their species diversity (H1) from 0.000 (2016) to 1.053 (2017) and 2.076 (2018) respectively.
High growth and survival rates of acropora formosa coral fragments and the increases pattern of fish diversity
found in this study suggested that the coral propagation is successful and feasible in increasing the fish
assemblages
Bioactive compounds derived from marine algae drawn increasing interest in pharmaceuticals, nutraceuticals, and cosmetics due to their wide range of therapeutic properties. These natural molecules, which include polysaccharides, polyphenols, phlorotannins, carotenoids, and pigments, exhibit potent antioxidant, antimicrobial, anti-inflammatory, antiviral, and antitumor activities. Algal bioactives are safer and more sustainable options for drug discovery since they often have less negative effects than synthesized compounds. This review highlights the structural diversity of algal biomolecules and their mechanisms of action, with emphasis on validated bioactivities supported by recent studies. It also critically examines challenges such as the low bioavailability of high-molecular-weight compounds like fucoidans, variability in metabolite production linked to environmental factors, and limitations in scalable extraction processes. Recent advances in nano-encapsulation, metabolic engineering, and eco-friendly extraction methods are explored as promising strategies to enhance bioavailability and industrial applicability. By integrating traditional knowledge with biotechnological innovations, this review underscores the underexploited potential of macroalgae in addressing chronic diseases and the urgent need for standardized protocols to facilitate the clinical translation of algal-derived bioactives.
Coral reefs host immense biodiversity. The species that live concealed within the reef matrix, the cryptobiome, represent a major component of this diversity and are essential to reef functioning. However, the drivers of their composition and distribution remain incompletely understood. We deployed 27 autonomous reef monitoring structures (ARMS) for 2 yr at 9 outer slope sites on the fringing reefs along the west and southwest coasts of Reunion Island (south-west Indian Ocean). Photo-analysis of the sessile cryptobenthic communities (SCCs) on ARMS plate faces revealed that Rhodophyta, Annelida, Bryozoa, Porifera, Foraminifera, and Ascidiacea were the most abundant taxa. Oceanic distance, habitat characteristics, and environmental parameters were analysed to assess factors controlling the SCCs at various spatial scales. Presence-absence and abundance-based dissimilarity metrics revealed the relative contributions of deterministic and stochastic processes driving SCC beta diversity. At the ARMS unit scale, SCC composition was strongly linked to plate face orientation and exposure to the environment. Along the Reunion coral reef coast, community dissimilarity was associated with discontinuities of reef habitat, grouping SCCs into 4 geographical zones based on environmental factors (sea surface temperature, wave height, water flow velocity). Our results suggest that the SCC membership of taxa may be primarily driven by stochastic processes such as random larval dispersal and settlement on each reef, while their relative abundance within the community may be influenced by deterministic niche-based processes. These findings improve our understanding of the drivers of coral reef biodiversity in support of the conservation of these ecosystems.
Successful larval recruitment is essential to the growth of coral reefs and therefore plays a key role in the recovery of degraded reefs worldwide. The rising intensity and frequency of environmental disturbance events and their effect on the establishment of new corals is outpacing the natural capacity of coral reefs to recover. To counter this, restoration programmes are increasingly turning to interventionist approaches to enhance coral recruitment, including mass-breeding corals in aquaria for subsequent deployment in the field. Coral sexual propagation has the potential to generate large numbers of genetically diverse coral recruits, but widespread application is still limited by the ability to reliably guarantee the successful settlement of coral larvae. Identifying the origins of biochemical cues that enhance coral settlement is a prerequisite to improving coral larval settlement on key locations and substrates. Microbial biofilms and microbes associated with crustose coralline algae have been shown to induce coral larval settlement, yet the specific taxa and mechanisms involved are poorly understood. In this review we synthes current literature on microbial settlement cues and the challenges associated with untaizengling the origin of individual cues originating within complex microbial communities. Furthermore, we call attention to the importance of interrogating microbial interactions with a holistic community approach to further our knowledge of both coral larval settlement inducers and inhibitors. Obtaining a better understanding of microbial interactions associated with coral settlement will lead to more effective approaches to restoration, from engineering inductive microbial communities to synthesising biochemical cues that can support coral larval settlement for aquaculture and reef recovery.
The composition and abundance of crustose coralline algae (CCA) have been documented in the Xinfeng algal reef (XAR). Eight CCA species were identified, including four in Phymatolithon ( P. margoundulatum , P. taiwanense , P. variabile , and Phymatolithon sp.) and four only identified to the genus level ( Chamberlainium sp. and three Dawsoniolithon spp.). Chamberlainium sp. was the most abundant species, while the three species of Dawsoniolithon were rarely observed. The CCA coverage varied from 18% ± 15% to 27% ± 21% in spring seasons of 2021–2024, but there were no significant differences. Based on carbon‐14 dating, the CCA sediments in the XAR were estimated to be 5850–5990 years old. These CCA sediments were primarily composed of two paleo‐CCA species, resembling modern Chamberlainium sp. and Dawsoniolithon sp. 1. However, the modern species of Phymatolithon , which are widespread and abundant in the algal reefs of northwestern Taiwan, were not observed in the CCA sediments. It is unclear whether their absence was due to fragile thalli after their death or their lack of occurrence, and this requires further investigation. The paleoenvironmental data and biogenic sediment composition analysis suggests that the XAR started to develop ~6000 years ago when the sea surface temperature began to decrease and seawater turbidity increased due to rainfall. Additional CCA sediment samples from this algal reef are needed to fully understand the historical changes in the paleo‐environments in the XAR.
The marine environment is an abundant source of organisms which are rich in functional/bioactive compounds. Many of these compounds exhibit a remarkable potential for medical, industrial and biotechnological applications. Handled appropriately, with a focus on sustainability, these organisms and compounds can offer new and renewable feedstocks for a variety of industries. The biomass from marine organisms also offers opportunities for clean and sustainable fuel generation, carbon sequestration and wastewater remediation.
Focusing on the use of biomass from marine algae (both macro and micro), bacteria and yeasts this book looks at opportunities for producing high value chemicals with applications across multiple industries. It is an essential read for researchers interested in innovative, green feedstock sources, sustainability and the circular economy.
Within Rhodophyta, with nearly 7100 known living species, the Corallinophycidae deserve main attention. Besides the crustose form, the coralline red algae are responsible for the rhodolith bed formation. With five orders, these algae present a complex taxonomy and a sub-estimated richness. This chapter describes their anatomical and reproductive characters, the diversity and distribution along the Brazilian Blue Amazon.
Brazilian reef environments are composed of a unique fauna. This chapter addresses the general biological and ecological aspects of 12 benthic reef-dwelling taxa found in Brazil: (i) scleractinian corals, which are primary reef-builders that produce the tridimensional framework; (ii) calcified hydrozoans belonging to the Millepora genus; (iii) other cnidarians such as octocorals, zoanthids and anemones; (iv) crustose coralline algae, which are also major reef-builders that produce extensive rhodolith beds; (v) bryozoans and (vi) vermetid gastropods, which have contributed significantly to reef-building in the Abrolhos Bank and Rocas Atoll, respectively; (vii) echinoderms, with emphasis on sea urchins, that control algal overgrowth through herbivory but may also contribute to bioerosion; (viii) sponges, which are abundant in Brazilian reefs and both add structural complexity and recycle organic matter, but also contribute to reef erosion; (ix) polychaetes and (x) mollusks, both of which may occasionally contribute to reef accretion and also engage in burrowing and erosion; (xi) crustaceans, which interact with numerous taxa and form multiple trophic links; and (xii) ascidians, a diverse cryptic dweller of the reef matrix. The basic morphology is presented for each taxon, as well as their diversity, reproductive biology and main functional roles.
Analyzing the environmental factors affecting benthic communities in coastal areas is crucial for uncovering key factors that require conservation action. Here, we collected benthic and environmental (physical-chemical-historical and land-based) data for 433 transects in Taiwan. Using a k-means approach, five communities dominated by crustose coralline algae, turfs, stony corals, digitate, or bushy octocorals were first delineated. Conditional random forest models then identified physical, chemical, and land-based factors (e.g., light intensity, nitrite, and population density) relevant to community delineation and occurrence. Historical factors, including typhoons and temperature anomalies, had only little effect. The prevalent turf community correlated positively with chemical and land-based drivers, which suggests that anthropogenic impacts are causing a benthic homogenization. This mechanism may mask the effects of climate disturbances and regional differentiation of benthic assemblages. Consequently, management of nutrient enrichment and terrestrial runoff is urgently needed to improve community resilience in Taiwan amidst increasing challenges of climate change.
Crustose coralline algae (CCA) are important ecosystem engineers and carbonate producers today and in the geological past. While there is an increasing number of publications on CCA every year, it is evident that there are many misunderstandings and inconsistencies in the assignment of CCA to taxonomic and functional groups. This is partly because CCA are treated by biologists, ecologists and palaeontologists as well as covered by studies published in journals ranging from geo- to biosciences, so that there is often a mixture of terminology used and differing scientific focus. In this review, a comprehensive overview is given on what is known about CCA, their functional traits and their roles in environments from the present and the past. In this context, some bridges are built between the commonly different viewpoints of ecologists and palaeontologists, including suggesting a common and straightforward terminology, highlighting and partially merging different taxonomic viewpoints as well as summarizing the most important functional traits of CCA. Ideally, future studies should seek to quantitatively analyse potential implications for CCA and their associated organisms under ongoing global change.
Habitat mapping is crucial for understanding habitat connectivity and for spatial planning, environmental management, conservation, and targeted research, including long-term change monitoring. However, such information has been lacking for many Dutch Caribbean islands, especially regarding marine habitats. This study used 2144 georeferenced images from different surveys to develop habitat models predicting the distribution of habitat types within the Saba Bank National Park. The habitat models link environmental factors to species or habitat occurrence, enabling predictions in unsurveyed areas with known covariates. Machine learning techniques (Random Forests, Gradient Boosting, and weighted K Nearest Neighbor) were applied to interpret and predict ten habitat types over the Bank. Three models were created for each technique: 1) utilizing only geographic coordinates; 2) incorporating covariables such as depth, distance to the edge of the Bank, Topographic Position Index (TPI), and Terrain Ruggedness index (TRI); 3) a combination of the previous two models. All models performed well, accurately predicting habitat types between 67 and 74% of the georeferenced images. However, the most natural representation occurred with models combining geographic and covariate variables. Predicted habitats include coral reef, patch reef, gorgonian reef, sargassum fields, cyanobacteria-dominated fields, Lobophora fields, Neogoniolithon- Lyngbya habitat, other macroalgae fields, sand with a mix of species, and bare sand. Habitat distribution appears to be related to the main currents in the area and depth, with coral reefs occurring mainly along the southern and eastern edge of the Bank, with gorgonians and other soft corals dominating there the shallow areas. Macroalgae, including fields of Sargassum, dominate the back-reef area. Extensive sand plains dominate the center of the Bank, and along the north-western and northern edge of the Bank, between 40 and 60m depth Lobophora fields can occur. In the south-eastern back reef area a number of mounds built up by the coralline alga Neogoniolithon occur. The Luymes Bank, the northeastern part of the Saba Bank, was the only area that was not correctly predicted, indicating that additional field-based observations are needed to refine results in this aree.
Crustose coralline algae (CCA) play a key role in invertebrate recruitment, yet their influence on the settlement of patellid
limpets is under discussion. This study is aimed at resolving the role of CCA as a settlement inducer for patellid limpets,
providing insight into the influence of different CCA-related factors. The larvae of the economically valuable limpet Patella
candei were used as a model. Six assays were performed: (1) different CCA assemblages, (2) exposure time, (3) artificial
removal of epibionts, (4) substrate area, (5) soluble cues (CCA-conditioned seawater), and (6) substrate selection in a choice
experiment. Settlers were identified by velum loss and teleoconch development. Species composition of the CCA assem-
blages significantly influenced settlement, with a preference for Titanoderma pustulatum and combined Neogoniolithon sp.
and Hydrolithon farinosum crusts. The substrates dominated by Agissea inamoena, marginal presence of CCA or which
epibionts were artificially removed, were statistically similar to those in the negative control. The ratio of settlers increased
until 4 days of exposure, after which it remained stable over time. The results support that CCA releases soluble cues with
settlement-inducing effect on P. candei larvae, explaining why the ratio of settlers increased with substrate area. The choice
experiment suggests that P. candei larvae have limited selectivity with respect to the substrate surface. In conclusion, the
present study points to the relevance of CCA assemblages as settlement substrates for limpet larvae, with an impact on limpet
recruitment in the wild as well as on the production of post-larvae for limpet aquaculture.
Porolithon is one of the most ecologically important genera of tropical and subtropical crustose (non‐geniculate) coralline algae growing abundantly along the shallow margins of coral reefs and functioning to cement reef frameworks. Thalli of branched, fruticose Porolithon specimens from the Indo‐Pacific Ocean traditionally have been called P. gardineri , while massive, columnar forms have been called P. craspedium . Sequence comparisons of the rbc L gene both from type specimens of P. gardineri and P. craspedium and from field‐collected specimens demonstrate that neither species is present in east Australia and instead resolve into four unique genetic lineages. Porolithon howensis sp. nov. forms columnar protuberances and loosely attached margins and occurs predominantly at Lord Howe Island; P. lobulatum sp. nov. has fruticose to clavate forms and free margins that are lobed and occurs in the Coral Sea and on the Great Barrier Reef (GBR); P. parvulum sp. nov. has short (<2 cm), unbranched protuberances and attached margins and is restricted to the central and southern GBR; and P. pinnaculum sp. nov. has a mountain‐like, columnar morphology and occurs on oceanic Coral Sea reefs. A rbc L gene sequence of the isotype of P. castellum demonstrates it is a different species from other columnar species. In addition to the diagnostic rbc L and psb A marker sequences, the four new species may be distinguished by a combination of features including thallus growth form, margin shape (attached or unattached), and medullary system (coaxial or plumose). Porolithon species, because of their ecological importance and sensitivity to ocean acidification, need urgent documentation of their taxonomic diversity.
Context
Settlement and metamorphosis are key processes influencing the natural recruitment and aquaculture production of aquatic organisms. Recruitment requirements in limpets (Patellogastropoda) are mostly unknown, because of the lack of reliable settlement inducers.
Aims
This study tested the reliability of different cues as settlement inducers for competent larvae of the economically valuable Patella aspera.
Methods
Natural crustose coralline algae (CCA) and biofilms of the benthic diatom Navicula salinicola were tested as positive controls. The following four pharmacological agents were tested as chemical inducers in a wide range of concentrations: gamma-aminobutyric acid (GABA), acetylcholine (ACH), 3-isobutyl-1-methylxanthine (IBMX) and potassium chloride (KCl). Settlers were identified by the velum loss and teleoconch development.
Key results
CCA were strong settlement cues in all the assays. Contrary to previous hypotheses, GABA was a weak inducer with a peak effect at 10⁻⁵ M. Neither the diatom biofilms nor the other pharmacological agents (ACH, IBMX and KCl) promoted the settlement response. All pharmacological agents at high concentrations influenced larval behaviour.
Conclusions
CCA were reliable positive controls and settlement inducers for the production of post-larvae. With regard to pharmacological agents, P. aspera showed restrictive settlement requirements that should be considered for ecological and aquaculture studies in other limpet species.
Implications
This method allows the study of the settlement biology of limpets. It provides a positive control and integrates animal monitoring and comparative response to other cues.
Crustose coralline algae (CCA) are important components of reef ecology contributing to reef framework construction. However, little is known about how seasonal upwelling systems influence growth and calcification of tropical CCA. We assessed marginal and vertical growth and net calcification rates of two dominant but morphologically different reef-building CCA, Porolithon antillarum and Lithophyllum cf. kaiseri, in a shallow coral reef of the Colombian Caribbean during upwelling and non-upwelling seasons. Growth and calcification rates varied seasonally with higher values during the upwelling compared to the non-upwelling (rainy) season. Annual vertical growth showed rates of 4.48 ± 1.58 and 4.31 ± 2.17 mm · y-1 , net calcification using crust growth estimates of 0.75 ± 0.30 g and 0.68 ± 0.60 g CaCO3 · cm-2 · y-1 and net calcification using the buoyant weight method of 1.49 ± 0.57 and 0.52 ± 0.11 g CaCO3 · cm-2 · y-1 in P. antillarum and L. kaiseri, respectively. Seawater temperature was inversely related with growth and calcification; however, complex oceanographic interactions between temperature and resource availability (e.g., light, nutrients, and CO2 ) are proposed to modulate CCA vital rates. Although CCA calcification rates are comparable to hard corals, CCA vertical accretion is much lower, suggesting that the main contribution of CCA to reef construction is via cementation processes. These results provide baseline data on CCA in the region and generate useful information for monitoring the impacts of environmental changes on tropical upwelling environments.
CaCO3 precipitates occur inside a few cyanobacteria and green algae. More common is precipitation on the surface of cyanobacteria, a range of algae and aquatic plants, and in invaginations of the cell wall in terrestrial plants (cystoliths). In coccolithophores and calcified dinoflagellates, CaCO3 is precipitated with organic matter in intracellular vesicles and the resulting structures are externalised. The precipitation of CaCO3 on the surface of photosynthesising structures is related to the consumption of CO2 in photosynthesis. CO2 production by root respiration can solubilise soil CaCO3. A few cyanobacteria and eukaryotic algae can bore through solid CaCO3 by removing Ca2+ and adding H+ at the site of boring, generating soluble inorganic C that can be used in photosynthesis. Ca(COO)2 is precipitated in the vacuoles of many algae and plants, and the cell walls of some plants.An outcome of precipitation of CaCO3 using CO3= produced from CO2, and Ca2+, is the production of H+; the same is the case for precipitation of Ca(COO)2 from (COOH)2 and Ca2+. The H+ produced by Ca(COO2) can be used to neutralise OH− produced in NO3− assimilation in the shoot without increasing cell osmolarity. There is no evidence of CaCO3 fulfilling this role. Another outcome of CaCO3 and Ca(COO)2 precipitation is Ca2+ immobilisation, though with little evidence of remobilisation of Ca2+ under Ca2+ deficiency. Other consequences of CaCO3 and Ca(COO)2 precipitation are light scattering and increased density, and ‘alarm photosynthesis’. Defence against herbivores and pathogens is better established for Ca(COO)2 than for CaCO3, and pollen release from anthers is a function of Ca(COO)2 but not CaCO3.KeywordsAcid-base regulationAlarm photosynthesisCalciumCarbonateInteractions with photonsOxalate
Aim
The Caribbean and Indo‐Pacific are separate biogeographical realms with distinct biogeographical and evolutionary histories, a 10‐fold difference in biodiversity, and highly disparate sea‐level histories. Since reef morphology often reflects interactions between biological activity and biogeographical history, including sea levels, the widths of shallow coral reef habitats are likely to differ markedly between realms, with ramifications for numerous ecosystem functions. Our goal, therefore, was to assess the impact of global‐scale biogeographical and evolutionary histories on coral reef habitats. Specifically, are Indo‐Pacific reefs wider than their Caribbean counterparts?
Location
Global.
Time Period
Modern.
Major Taxa Studied
Coral reefs.
Methods
We used the Allen Coral Atlas, a global reef mapping system (3 m pixel resolution), to examine 3765 transects, 3 km long and 1 km apart, on 60 reefs across the two realms, quantifying shallow reef habitat widths (Inner and Outer Reef Flat, and Reef Crest) using ArcGIS.
Results
Shallow reef habitat widths were strikingly similar between the Caribbean and Indo‐Pacific. Estimated modal widths diverged by just 37 m; means by just 122 m. Although shallow reef zones appeared to be wider in the Indo‐Pacific, habitat widths on atolls were almost identical across realms (means varying by less than 8 m).
Main Conclusions
Our remote sensing approach provides a global description of the biogeography of coral reefs as biogenic structures. Furthermore, we can assess the relative importance of realm‐wide differences in coral diversity and sea‐level history on reef growth. The striking similarity of reef widths across realms suggests that reef growth (net reef accretion) is largely independent of coral diversity, or sea‐level history, and that other factors may have played a major role in constraining shallow reef widths. These factors may include geomorphology (e.g. antecedent topography and historical accommodation space) and, once at sea level, self‐limiting local hydrodynamics.
Ocean warming (OW) and marine heatwaves (MHWs) rapidly transform marine ecosystems, especially when they impact keystone or foundation species. Foundation species such as kelps, fucoids and corals are highly sensitive to heat stress, which threatens the future of temperate seaweed forests and tropical reefs. However, functioning and resilience of these systems also relies on the less conspicuous coralline algae, whose thermal tolerances have gone largely untested. Here, we examined the sensitivity of four temperate coralline algal morphotypes from three different species to four realistic present day and future OW and MHW scenarios (ambient [16°C constant]; ambient+MHW [16°C baseline + a symmetric two-week heatwave with a peak intensity of 18.7°C]; future [18.7°C constant]; future+MHW [18.7°C baseline + a symmetric two-week heatwave with a peak intensity of 21.4°C]). Photo-physiology (e.g., Fv/Fm) and calcification physiology (e.g., proxies for calcifying fluid saturation state ΩCF) were generally unaffected by the treatments, implying a high thermo-tolerance of our study species compared to other important marine foundation species. We ascribe this mainly to their photosynthetic apparatus that, unlike in other photoautotrophs, continued to function under heat stress. Experimental evidence presented here and elsewhere implies that coralline algae are likely to continue to play their crucial ecological roles in a warming ocean. Yet, such predictions are fraught with uncertainty due to the substantial gaps in our knowledge. We attempt to highlight some of these gaps and aim to present potential physiological underpinnings of their thermo-tolerance.
The Serpulidae are a large family of sedentary polychaetes, characterized by a calcareous habitation tube, which they cannot leave. The calcium carbonate tube is in the form of both aragonite and calcite, in fairly constant ratio for each taxon. Tubes are cemented firmly to any hard substrate (in only few species tubes are free). Although in the majority of the species the tubes encrust the substrate for all their length, the distal part may eventually detach and grow erectly. Certain species in dense populations build tubes vertical to the substrate in clumps and cement the tubes to each other. This gives serpulids the capability of forming reef-life structures when densely settling. Despite the relative smallness of the individual tubes (rarely longer than 15 cm and wider than 1 cm), such reef-like structures may cover tens of m², with a layer more than 1 m thick. Serpulid reefs can be divided roughly into seven groups, according to the building modality and the type of habitat they occupy: (i) pseudocolonies; (ii) littoral belts; (iii) subtidal to deep-water reefs; (iv) reefs in coastal lakes and harbours; (v) brackish water reefs; (vi) tapestries in freshwater caves; (vii) biostalactites inside marine caves. The role of serpulid reefs in the ecosystems they inhabit is multifarious and may be distinguished in functions (biomass and production, benthic pelagic coupling, resistance and resilience, reproductive and survivorship strategies, trophodynamics, bioconstruction, living space and refuge, nursery, sediment formation and retention, food for other species, carbonate deposition and storage) and services (water clearance, reef associated fishery, cultural benefits). On the other hand, many serpulids are important constituents of biological fouling, and their calcareous masses damage submerged artefacts, causing huge economic costs. Positive and negative roles of serpulid reefs need to be compared with common metrics; the overall balance, however, is still to be assessed.
Niche differentiation is a key stabilizing mechanism in the maintenance of biodiversity and species coexistence. Recent work shows that trophic niche partitioning between parrotfishes (Labridae: Scarini) is more extensive than previously described. One Indo-Pacific species, Scarus spinus , appears highly specialized, scraping crustose coralline algae (CCA) with powerful oral jaws. CCA are of low nutritional value, suggesting that the dietary targets of this parrotfish are protein-rich microphotoautotrophs associated with CCA, particularly filamentous cyanobacteria. We collected feeding substrata samples at mid-shelf and outer-shelf sites near Lizard Island, Great Barrier Reef, Australia, in 2018 and 2019, respectively. Scarus spinus were followed on snorkel. When biting was observed, bite substrata were photographed and then a 22-mm-diameter core extracted around the bite site. Density of biota including filamentous cyanobacteria and diatoms was quantified microscopically on photographs of the bite cores (up to 630 × magnification). The taxonomy of cyanobacteria and CCA was refined using next-generation sequencing of 16S and 18S rRNA genes, respectively. CCA and filamentous cyanobacteria were present on all bite cores and the density of filamentous cyanobacteria where S. spinus fed did not vary between mid-shelf and outer-reef samples. Epiphytic and shallow endophytic cyanobacteria were consistently associated with the CCA where S. spinus fed, including Calothrix spp., Mastigocoleus testarum , Leptolyngbya spp . , Hyella patelloides and Oscillatoriales. Our results emphasize the importance of high-resolution species-specific dietary data for parrotfishes. We conclude that polyphasic methods are essential both for diet tracing and to develop our understanding of the cyanobacteria that are integral to coral reef functioning.
algae and rises up from the seamount summit at 60-70 m to 17 m depth. The benthic community is mainly composed by coralline algae and sponges. Fish biomass at Davis coralline hill is dominated by carnivores, mainly top predators such as nurse sharks and large groupers. The relatively shallow reef top presents higher species richness, abundance and distinct trophic structure (mostly omnivore and planktivore species) than the mesophotic zone (with higher abundance of carnivorous fishes). A biogeographic analysis revealed that the reef fish community structure is greatly influenced by a set of dispersal and establishment traits that strongly differs from that encountered on coastal reefs of the central Brazilian coast and on insular reefs of Trindade Island. Gathering information about the ecology and structure of such unique and remote habitat is timely, since the region is under imminent threat such as fishing and mining and lacks international attention.
Algal reefs, concreted by crustose coralline algae (CCA), are the main biotic reefs in temperate waters but rare in the subtropics and tropics. The world's largest known intertidal algal reef in the subtropics is the Taoyuan Algal Reef (TAR) located in the northwestern coast of Taiwan. The biodiversity and ecology of the TAR are scarcely explored, and now the reef is imperiled by industrialization. Here, we document cryptic species of CCA in Taiwan, particularly the TAR, by sequencing the psbA genes of over 1800 specimens collected across Taiwan. We also examine the ecological background of the TAR by surveying its benthic composition and measuring its environmental parameters. Our data reveal that the TAR harbours a high diversity of cryptic CCA species (27 molecular operational taxonomic units, or mOTUs), many of which are potentially new to science (18 mOTUs) and/or endemic to the TAR (9 mOTUs). Comparing the CCA species inventory of the TAR with the rest of Taiwan shows that the TAR represents a unique hotspot of CCA taxa in the waters of Taiwan. Our analyses show that variation in the CCA assemblages in the TAR is associated with geographic distance, sedimentation, and substrate type (for example, reef vs. hermit crab shell), suggesting that dispersal limitation and contemporary environmental selection shape the CCA assemblages in the TAR. The data from this study can inform the monitoring of human impacts on the health of the TAR and contribute to our understanding of the ecological processes underlying algal reef development.
Recently, increased attention is being paid to the importance of environmental history in species’ responses to climate-change related stressors, as more variable and heterogeneous environments are expected to select for higher levels of plasticity in species tolerance traits, compared to stable conditions. For example, organisms inhabiting environments with highly fluctuating thermal regimes might be less susceptible to the increasing frequency and intensity of marine heatwaves (MHWs). In this study, we assessed the metabolic and calcification responses of the rhodolith-bed forming Phymatolithon lusitanicum, from a coastal region that is strongly influenced by frequent changes between upwelling and downwelling conditions, to a simulated MHW scenario, with and without prior exposure to a moderate thermal stress. This allowed determining not only the influence of the species’ long-term thermal history on its resilience against MHWs, but also the rhodoliths capacity for short-term thermal stress memory and its importance during posterior MHW-exposure. Our findings indicate that the rhodoliths experienced negative impacts on daily net primary production (DNP) and calcification (DNC) during the MHW. The effect on the former was only temporary at the beginning of the MHW, while DNC was highly impacted, but exhibited a quick recovery after the event, suggesting a high resilience of the species. Furthermore, prior exposure to a moderate temperature increase, such as those occurring frequently in the natural habitat of the species, mitigated the effects of a subsequent MHW on DNP, while promoting a faster recovery of DNC after the event. Thus, our findings (1) support the hypothesis that benthic organisms living in nearshore habitats may benefit from the natural short-term temperature fluctuations in these environments with an increased resistance to MHW impacts and (2) provide first-time evidence for thermally induced stress memory in coralline algae.
Crustose coralline algae (Corallinophycideae) are red algae that produced calcium carbonate and are well recognized as foundation species in the epipelagic zone of the marine ecosystem. These algae induced settlement juvenile of coral by released chemical cues from bacterial communities on the surface of their colonies. Their extracellular calcium carbonate also can stabilize reef structure that influencing many invertebrate attaches and growth in the seabed. Crustose coralline algae (CCA) have obtained attention because of their distribution and health compromise to increasing seawater temperature, ocean acidification, and pollutant. As a cryptic species in the ecosystem, the presence of CCA recruit sometimes doesn't have attention, especially on their capability to occupy the empty space. This study aimed to document coverage and number of CCA recruit in two different recruitment tile's material. The highest CCA percentage of the cover was showed inside surface than others surface in all stations. Light intensity and low sedimentation were suggested as a key factor of success of high coverage. Overall, station higher CCA recruits have shown from Tiga Warna. Low sedimentation and protection from aerial exposure became the main reason for it. No significant difference number of CCA recruits between marble and sandstone in this study. Successful CCA recruitment in this study can give a wide picture that natural recruitment of coral and other reef biodiversity in Southern Malang might be will succeed because of the abundance of coralline algae that support their life history stage.
A R T I C L E I N F O Keywords: 18th century Artificial reef Crustose coralline algae Turf algae Palythoa caribaeorum Millepora spp. A B S T R A C T With increasing maritime activities in the proximity of coral reefs, a growing number of manmade structures are becoming available for coral colonisation. Yet, little is known about the sessile community composition of such artificial reefs in comparison with that of natural coral reefs. Here, we compared the diversity of corals and their competitors for substrate space between a centuries-old manmade structure and the nearest natural reef at St. Eustatius, eastern Caribbean. The artificial reef had a significantly lower species richness and fewer competitive interactions than the natural reef. The artificial reef was dominated by a cover of crustose coralline algae and zoantharians, instead of turf algae and fire corals on the natural reef. Significant differences in species composition were also found between exposed and sheltered sites on both reefs. Our study indicates that even a centuries-old manmade reef cannot serve as a surrogate for natural reefs.
Adaptive diversification is a product of both phylogenetic constraint and ecological opportunity. The species-rich parrotfish genera Scarus and Chlorurus display considerable variation in trophic cranial morphology, but these parrotfishes are often described as generalist herbivores. Recent work has suggested that parrotfish partition trophic resources at very fine spatial scales, raising the question of whether interspecific differences in cranial morphology reflect trophic partitioning. We tested this hypothesis by comparing targeted feeding substrata with a previously published dataset of nine cranial morphological traits. We sampled feeding substrata of 15 parrotfish species at Lizard Island, Great Barrier Reef, Australia, by following individuals until focused biting was observed, then extracting a bite core 22 mm in diameter. Three indices were parameterized for each bite core: substratum taphonomy, maximum turf height and cover of crustose coralline algae. Parrotfish species were spread along a single axis of variation in feeding substrata: successional status of the substratum taphonomy and epilithic and endolithic biota. This axis of trophic variation was significantly correlated with cranial morphology, indicating that morphological disparity within this clade is associated with interspecific partitioning of feeding substrata. Phylogenetic signal and phylomorphospace analyses revealed that the evolution of this clade involved a hitherto-unrecognized level of trophic diversification.
Crustose coralline red algae (CCA) play a key role in the consolidation of many modern tropical coral reefs. It is unclear, however, if their function as reef consolidators was equally pronounced in the geological past. Using a comprehensive database on ancient reefs, we show a strong correlation between the presence of CCA and the formation of true coral reefs throughout the last 150 Ma. We investigated if repeated breakdowns in the potential capacity of CCA to spur reef development were associated with sea level, ocean temperature, CO2 concentration, CCA species diversity, and/or the evolution of major herbivore groups. Model results show that the correlation between the occurrence of CCA and the development of true coral reefs increased with CCA diversity and cooler ocean temperatures while the diversification of herbivores had a transient negative effect. The evolution of novel herbivore groups compromised the interaction between CCA and true reef growth at least three times in the investigated time interval. These crises have been overcome by morphological adaptations of CCA.
Coralline algae, a major calcifying component of coastal shallow water communities, have been shown to be one of the more vulnerable taxonomic groups to ocean acidification (OA). Under OA, the interaction between corallines and epiphytes was previously described as both positive and negative. We hypothesized that the photosynthetic activity and the complex structure of non-calcifying epiphytic algae that grow on corallines ameliorate the chemical microenvironmental conditions around them, providing protection from OA. Using mesocosm and microsensor experiments, we showed that the widespread coralline Ellisolandia elongata is less susceptible to the detrimental effects of OA when covered with non-calcifying epiphytic algae, and its diffusive boundary layer is thicker than when not covered by epiphytes. By modifying the microenvironmental carbonate chemistry, epiphytes, facilitated by OA, create micro-scale shield (and refuge) with more basic conditions that may allow the persistence of corallines associated with them during acidified conditions. Such ecological refugia could also assist corallines under near-future anthropogenic OA conditions.
Polycyathus chaishanensis is a symbiotic caryophyllid coral described from a single population in a tidal pool off Chaishan, Kaohsiung, Taiwan. Due to its rarity, P. chaishanensis was declared a critically-endangered species under the Taiwan Wildlife Protection Act. In May 2017, a P. chaishanensis colony was discovered in the intertidal area of the Datan Algal Reef, Taoyuan, Taiwan. To determine whether this is a stable population in the algal reef, a demographic census—including data on occurrence, distribution, and colony size—was carried out in the algal reef in southern Taoyuan. Intertidal censuses and sediment collections were conducted at five different sections—Baiyu, Datan G1, Datan G2, Yongxing, and Yongan algal reefs—during the monthly spring low tide from July 2018 to January 2019. In total, 84 colonies—23 in Datan G1 and 61 in Datan G2—were recorded from a tidal range of − 160 to − 250 cm, according to the Taiwan Vertical Datum 2001 compiled by the Central Weather Bureau. No P. chaishanensis was found in Baiyu, Yongxing, or Yongan. The P. chaishanensis colony sizes ranged from 2.55 to 81.5 cm in diameter, with the larger P. chaishanensis present in the lower intertidal zone. Sediment was extremely high, with monthly site averages ranging from 3,818.26 to 29,166.88 mg cm⁻² day⁻¹, and there was a significant difference between sites and months, both of which affected the distribution of P. chaishanensis in the algal reef. Our study confirms the existence of a second population of P. chaishanensis in Taiwan, highlighting the importance of the Datan Algal Reef for the survival and protection of this critically-endangered caryophyllid coral and why it is so urgent that the reef should be conserved.
Parrotfishes (Scarini) are considered key agents in coral reef health and recovery, but the drivers of parrotfish–coral dynamics remain contentious. The prevailing view of parrotfishes as ecosystem engineers is based on the perceived removal of algal turf, macroalgae and sediment, but these are effects of feeding, not causes. The recent proposal that most parrotfishes are ‘microphages’ that target microscopic photoautotrophs (particularly cyanobacteria) identifies the need to resolve dietary targets at a microscopic scale. Here, we investigate parrotfish dietary targets by posing the following two questions: (1) are microscopic photoautotrophs the most consistent and dominant elements of the prey community, and (2) do the prey community and substratum taphonomy vary between parrotfish species? In order to identify and quantify dietary targets, five parrotfish species were followed until focused feeding was observed at Lizard Island on the Great Barrier Reef, Australia. Feeding sites were photographed in situ and extracted as substratum bite cores. Cores were analysed microscopically to identify and quantify all epilithic photoautotrophs. Endolithic photoautotrophs accessible to excavating parrotfish were also investigated by vacuum-embedding cores with epoxy resin followed by decalcification to expose endolith microborings. The dominant functional groups of epilithic biota on the cores were tufted cyanobacteria, turfing algae and crustose coralline algae (CCA). The only consistent feature across all cores was the high density of filamentous cyanobacteria, supporting the view that these parrotfishes target microphotoautotrophs. Macroalgae was absent or a minor component on cores, supporting the hypothesis that parrotfishes avoid larger algae. The microchlorophyte Ostreobium was the dominant photoautotrophic euendolith (true borer) in the cores of the excavating parrotfish Chlorurus microrhinos. Significant differences in CCA coverage, turf height and substrate taphonomy were found among the five parrotfish species, suggesting that interspecific resource partitioning is based on successional stage of feeding substrata.
Marine organisms in the Mediterranean Sea experience the highest temperatures, salinities and oligotrophic conditions in its easternmost part along the eastern shores of the Levantine basin. Over the past three decades this region has warmed by ca. 1.5–3.08C with current winter and summer extremums of 178C and 318C, respectively. In this study, we tested the response of the native abundant articulated coralline red alga Ellisolandia elongata to this warming. Coralline algae play a key role in coastal ecosystems by structuring marine habitats, providing shelter for a myriad of species, and substantially influencing the coastal carbon budget. Despite being ubiquitous along the Levantine coasts, coralline’s ecology, physiology, and biogeochemical role are nearly unknown as well as their performance under different temperatures. Measurements
of primary production, respiration and calcification in the temperatures range 15–358C, which represent past, present and predicted local annual conditions, indicated two physiological tipping points: 1) metabolic breakdown above 318C; 2) metabolic shift at 238C, possibly promoting seasonal algal heterotrichy (perennation of the alga without its fronds). Annual production rates were evaluated under the current and predicted temperature regimes indicating a loss of ca. one third of the organic carbon and carbonate production by corallines contributed to the shallow Levantine coast in the upcoming decades. We predict that with continued warming, Eastern Mediterranean corallines will experience a westward range contraction, initiating with phenological
shifts, followed by performance declines and population decreases, ending with local extinctions.
Miocene carbonates in the Mediterranean are dominated by organic buildups of rhodalgal and coral-reef facies with local stromatolitic mounds, ahermatypic coral mounds and oyster banks and occur in a wide variety of tectonic settings and substrates. Regional chronostratigraphic correlation is in a state of flux, but it appears that coral reef development was extensive during the climatic optimum of the Chattian-Aquitanian, Langhian and Late Tortonian-Messinian times. The coral reef provinces of the Mediterranean reflect the transition between Early Miocene open-oceanic, humid-tropical conditions and Late Miocene land-locked, semi-arid and marginally subtropical environments. Narrow platforms with fringing reefs are predominant; lagoonal facies are poorly developed and commonly with variable amounts of terrigenous mixing. Extensive carbonate platforms with barrier reefs and lagoons occur in Oligocene-Lower Miocene carbonates but are very scarce or ephemeral in Upper Miocene platforms. Depositional sequences of different orders of magnitude display a basic stacking pattern consisting of vertical aggradation, progradation and offlaping (downstepping); faithfully reflecting inferred relative sea-level oscillations. Coral diversity decreased from Early to Late Miocene times. The largest Upper Miocene reef complexes tend to be monogeneric and show good vertical zonation in colonial morphologies. Upper Miocene coral reefs developed before, during and after the repeated deposition of basinal evaporite units and marine marls, resulting in complex wedge-on-wedge geometries of difficult correlation. Miocene carbonates have a marked cyclicity of different orders of magnitude, particularly well recorded on Upper Miocene platforms.
Rhodoliths (free-living coralline red algae) can thrive under a wide range of temperatures, reduced light, and increased nutrient levels, and often form a distinct so-called rhodalgal lithofacies that is an important component of Cenozoic shallow-water carbonates. Global distributions illustrate that from the late-early to early-late Miocene (Burdigalian early Tortonian), rhodalgal facies reached peak abundances and commonly replaced coral-reef environments, accompanied by a decline in other carbonate-producing phototrophs. We argue that the dominance of red algae over coral reefs was triggered in the Burdigalian by enhanced trophic resources associated with a global increase in productivity, as evidenced by a long-term shift toward higher carbon isotope values. Rhodalgal lithofacies expanded further in the middle Miocene when strengthened thermal gradients associated with the establishment of the East Antarctic Ice Sheet led to enhanced upwelling while climate change generated increased weathering rates, introducing land-derived nutrients into the oceans. Globally cooler temperatures following a climatic optimum in the early-middle Miocene contributed to sustain the dominance of red algae and prevented the recovery of coral reefs. The global shift in nearshore shallow-water carbonate producers to groups tolerant of higher levels of trophic resources provides further evidence for increased nutrient levels during that time interval and shows the sensitivity of shallow-water carbonate facies as indicators of past oceanographic conditions.
A conceptual paradigm, the “Relative Dominance Model”, provides the perspective to assess the interactive external forcing-mechanisms controlling phase shifts among the dominant benthic functional groups on tropical coral reefs [i.e., microalgal turfs and frondose macroalgae (often harmful) versus reef-building corals and calcareous coralline algae (mostly beneficial due to accretion of calcareous reef framework)]. Manipulative experiments, analyses of existing communities and bioassays tested hypotheses that the relative dominances of these functional groups are mediated by two principal controlling factors: nutrients (i.e., bottom-up control) and herbivory (i.e., top-down control). The results show that reduced nutrients alone do not preclude fleshy algal growth when herbivory is low, and high herbivory alone does not prevent fleshy algal growth when nutrients are elevated. However, reduced nutrients in combination with high herbivory virtually eliminate all forms of fleshy micro- and macro-algae. The findings reveal considerable complexity in that increases in bottom-up nutrient controls and their interactions stimulate harmful fleshy algal blooms (that can alter the abundance patterns among functional groups, even under intense herbivory); conversely, elevated nutrients inhibit the growth of ecologically beneficial reef-building corals. The results show even further complexity in that nutrients also act directly as either limiting factors (e.g., physiological stresses) or as stimulatory mechanisms (e.g., growth enhancing factors), as well as functioning indirectly by influencing competitive outcomes. Herbivory directly reduces fleshy-algal biomass, which indirectly (via competitive release) favors the expansion of grazer-resistant reef-building corals and coralline algae. Because of the sensitive nature of direct/indirect and stimulating/limiting interacting factors, coral reefs are particularly vulnerable to anthropogenic reversal effects that decrease top-down controls and, concomitantly, increase bottom-up controls, dramatically altering ecosystem resiliencies.
The discovery of abundant autotrophic macrophytes living below 200 meters indicates their importance to primary productivity,
food webs, sedimentary processes, and as reef builders in clear oceanic waters. Estimates concerning minimum light levels
for macroalgal photosynthesis and macrophytic contributions to the biology and geology of tropical insular and continental
borderlands must now be revised.
Ocean acidification in response to rising atmospheric CO2 partial pressures is widely expected to reduce calcification by marine organisms. From the mid-Mesozoic, coccolithophores
have been major calcium carbonate producers in the world's oceans, today accounting for about a third of the total marine
CaCO3 production. Here, we present laboratory evidence that calcification and net primary production in the coccolithophore species
Emiliania huxleyi are significantly increased by high CO2 partial pressures. Field evidence from the deep ocean is consistent with these laboratory conclusions, indicating that over
the past 220 years there has been a 40% increase in average coccolith mass. Our findings show that coccolithophores are already
responding and will probably continue to respond to rising atmospheric CO2 partial pressures, which has important implications for biogeochemical modeling of future oceans and climate.
In addition to salinity and temperature, nutrient concentrations in surface waters are known to have a significant impact on distribution of carbonate-producing biota, but have never been quantitatively evaluated against different temperatures along a latitudinal transect. The western coast of the Gulf of California, Mexico, presents a natural laboratory for investigating the influence of oceanographic parameters such as salinity, temperature, and chlorophyll a, a proxy for nutrients, on the composition of a range of modern heterozoan and photozoan carbonate environments along a north-south latitudinal gradient spanning the entire warm-temperate realm (29degreesN-23degreesN). Chlorophyll a, measured in situ at half-hour resolution, is highly variable throughout the year due to short-term upwelling, and increases significantly from the southern to northern Gulf of California. Salinity, in contrast, fluctuates little and remains at an average of 35%. From south to north, carbonate production ranges from oligotrophic-mesotrophic, coral reefdominated shallow-water areas (minimum temperature 18.6 degreesC) through mesotrophic-eutrophic, red algal-dominated, inner-shelf carbonate production in the central gulf (minimum temperature 16 degreesC), and to molluscan-bryozoan, eutrophic inner- to outer-shelf environments (minimum temperature 13.7 degreesC). The Gulf of California data, supplemented with oceanographic and compositional information from a database compiled from a spectrum of modern carbonate systems worldwide, demonstrates the significance of nutrient control in the formation of heterozoan, photozoan, and transitional heterozoan-photozoan carbonate systems and serves as a basis for more accurately interpreting fossil carbonates.
The intimate association between a selective herbivore (the chiton Choneplax lata) and its primary prey (the crustose coralline alga Porolithon pachydermum) results in increased biomass and accretion of the alga. This process, over ecological and geological time scales, comprises a major component of Caribbean reef-building systems. Manipulative experiments showed that as the chiton grazes the alga it stimulates new meristematic activity and removes sporlings of the competitively superior frondose and filamentous algae, thereby increasing the survival rate of P. pachydermum on the intertidal reef crest. Furthermore, in the absence of C. lata, overgrowths of frondose and filamentous epiphytes provide an attractive food source for parrotfishes (Scaridae), which accelerates bioerosion of the coralline reef-crest structure due to the deep rasping action of feeding activity. Algal removal experiments suggest that the role of P. pachydermum is to provide a predictable food source and refuge substratum, which increases survivorship of the burrowing chiton by minimizing expenditure of energy during foraging and risk of predation. The chiton/coralline alga association is abundant throughout tropical western Atlantic islands and augments reef-building processes on the shallow algal crest portion of Caribbean reefs. Cover of the Choneplax/Porolithon association in the Belize Barrier Reef crest averages 13% (maximum to 70%) with a mean chiton density of 664 individuals/m^2 within the association. On average, the extensive networks of interconnected chiton burrows extend between 6 and 10 cm deep and contain one C. lata for every six openings, with the majority of animals (66%) ranging from 16 to 30 mm in length. Gut contents of the chiton consist predominantly of P. pachydermum (51%), followed by bacterial detritus (30%), Cyanophyta (13%), Bacillariophyta (3%), and fleshy microalgae (3%). The close SEM (scanning electron microscope) match between radular morphology of C, lata and grazing scars on the thallus surface of P. pachydermum shows how the chiton regularly feeds on the coralline alga without causing mortality. Virtually all P. pachydermum in the vicinity of C. lata burrows contain radular tract scars of @?10 @mm in depth, whereas the photosynthetic meristematic, and reproductive tissues of coralline lie below 20 @mm. P. pachydermum under intense chiton grazing is photosynthetically competent with 0.1 mg C fixed@?g^-^1 organic dry mass@?^-^1, which is not significantly different from ungrazed material and within the range of rates for other crustoe coralline algae. The result is continuous net accretion at a mean rate of 2.3 mm/yr.
An overview of nongeniculate "corallinaceae" collection, preservation and examination of material taxonomic literature on nongeniculate "corallinaceae" historical analysis features diagnostic of subfamilies and genera the identification of Holocene subfamilies and genera accounts of Holocene subfamilies and genera Holocene genera requiring further evaluation, genera of uncertain status and excluded genera. Appendices: 1 - the terms primigenous and postigenous B - nomenclatural change C - list of herbarium abbreviations.
Articulated and non-articulated coralline algae were brought together in the family Corallinaceae in essentially its present-day circumscription by Decaisne in 1842. Since that time, this family has been perceived as one of the most distinctive assemblages of Rhodophyceae. Alignment of families of red algae into orders based on criteria that today are considered to reflect natural relationships extends back only as far as 1892, when Schmitz presented a scheme founded largely on details of the female reproductive system and gonimoblast development. In that scheme, the Corallinaceae occupied an anomalous position in the Cryptonemiales. While attempts have been made to modify the definition of the Cryptonemiales to accommodate the Corallinaceae more comfortably, an ongoing accumulation of information supports the segregation of that family into its own order. At least three previous authors have adopted the taxonomic concept of the Corallinales, but the name has not yet been validated. In the present paper a Latin diagnosis is provided. Diagnostic characters of the Corallinales include the following: (1) walls of most vegetative cells are impregnated with calcite; (2) meristems are often intercalary and covered by a layer of cells; (3) plugs of primary pit-connections have two-layered, dome-shaped caps; (4) reproductive structures are produced in roofed conceptacles in all genera but one; (5) tetrasporocytes usually undergo simultaneous zonate division; (6) post-fertilization events involve a cluster of procarpial filament systems.
Data from a comprehensive literature survey for the first time provide stage-level resolution of Early Cretaceous through Pleistocene species diversity for nongeniculate coralline algae. Distributions of a total of 655 species in 23 genera were compiled from 222 publications. These represent three family-subfamily groupings each with distinctive present-day distributions: (1) Sporolithaceae, low latitude, mainly deep water; (2) Melobesioid corallinaceans, high latitude, shallow water, to low latitude, deep water; (3) Lithophylloid/mastophoroid corallinaceans, mid- to low latitude, shallow water. Raw data show overall Early Cretaceous–early Miocene increase to 245 species in the Aquitanian, followed by collapse to only 43 species in the late Pliocene. Rarefaction analysis confirms the pattern of increase but suggests that scarcity of publications exaggerates Neogene decline, which was actually relatively slight. Throughout the history of coralline species, species richness broadly correlates with published global paleotemperatures based on benthic foraminifer δ18O values. The warm-water Sporolithaceae were most species-abundant during the Cretaceous, but they declined and were rapidly overtaken by the Corallinaceae as Cenozoic temperatures declined. Trends within the Corallinaceae during the Cenozoic appear to reflect environmental change and disturbance. Cool- and deep-water melobesioids rapidly expanded during the latest Cretaceous and Paleocene. Warmer-water lithophylloid/mastophoroid species increased slowly during the same period but more quickly in the early Oligocene, possibly reflecting habitat partitioning as climatic belts differentiated and scleractinian reef development expanded near the Eocene/Oligocene boundary. Melobesioids abruptly declined in the late Pliocene–Pleistocene, while lithophylloid/mastophoroids increased again. Possibly, onset of glaciation in the Northern Hemisphere (∼2.4 Ma) sustained or accentuated latitudinal differentiation and global climatic deterioration, disrupting high-latitude melobesioid habitats. Simultaneously, this could have caused moderate environmental disturbance in mid- to low-latitude ecosystems, promoting diversification of lithophylloids/mastophoroids through the “fission effect.” Extinction events that eliminated >20% of coralline species were most severe (58–67% of species) during the Late Cretaceous and late Miocene–Pliocene. Each extinction was followed by substantial episodes of origination, particularly in the Danian and Pleistocene.
Selbst im klarsten ozeanischen Meerwasser dringt das Licht kaum tiefer ein als 180 m. Daher konnte wohl niemand erwarten, photosynthetisch aktive Pflanzen in den nachtdunklen Tiefen darunter zu finden.
Aber es gibt sie dort: Im Lichtkegel des Forschungstauchbootes Johnson-Sea-Link entdeckten wir im Oktober 1985 vor den Bahamas quadratmetergroße Flecken mit einer bisher unbekannten Rotalge, die selbst in einer Rekordtiefe von 274 m unterhalb der Wasseroberfäche offensichtlich recht gut gedieh (siehe nebenstehende Abbildung). Diese Pflanzen wuchsen tiefer als an irgendeiner anderen Stelle der Erde.
Die neu entdeckten Algen erwiesen sich somit als die am weitesten in die Tiefe vordringenden Makrophyten (ohne optische Hilfe erkennbare Individuen).
This study provides the first quantitative measures of deep-water (i.e., below scuba depths) rhodolith development, distribution, abundance, and primary productivity at sites of both active formation and breakdown. The 1.27-km² upper platform surface of San Salvador Seamount, Bahamas, ranges in depth from 67 to 91 m and averages 95.8% cover of rhodoliths that contribute an estimated 391 t organic C·yr⁻¹ to deep-sea productivity. The predominant nongeniculate coralline alga of the slope environment has an extremely narrow PI curve (photosynthesis vs. irradiance) of net primary production (0.005) to slightly beyond 0.24 μmol·m⁻²·⁻¹ PAR) suggesting that some deep-water benthic algae may be acclimated to restricted light ranges. Platform areas contain up to fice-deep accumulations (≈45 cm thick) of rhodoliths with their visible, planar (2-D), crustose algal cover (68.5%) composed of 41% Lithophyllum sp., 14.9% average nongeniculate corallines, and 12.6% Peyssonnelia sp. Platform rhodoliths also contain ≈25% average planar cover of the foraminiferan Gypsina sp. overlying the rock-penetrating chlorophyte Ostreobium sp.
Notice sur les Polypiers de la Grèce
- J B Bory De Saint-Vincent
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Being the first part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy, R.N. During the years 1832 to 1836
- C R Darwin
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Recognition and selection of settlement substrata determine post-settlement survival in corals
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- A Negri
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The crustose coralline alga, Phymatolithon Foslie, inhibits the overgrowth of seaweeds without relying on herbivores
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Calcium carbonate production and carbon dioxide flux on a coral reef, okinawa
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Coralline bone graft substitutes
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A voyage to the islands
- H Sloane
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- Jamaica Christophers
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