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The most important reef of the Mediterranean is the Coralligène (Coralligenous = C), including several types of calcareous algal-invertebrate build-ups growing in normal open marine conditions. We analyzed and compared two C samples from the Ligurian Sea developed in different environmental settings: 1) off Portofino on a rocky cliff, at a depth of about 40 m and 2) in front of Bogliasco, on a sub-horizontal substrate at a depth of 10 m. The maximum AMS radiocarbon dating provided an older age for Bogliasco (about 5 ka BP) than for Portofino (about 3.6 ka BP), and the mean accumulation rate of the Portofino build-up (about 80 µm y−1) was found to be higher than the one in Bogliasco (about 65 µm y−1). The different sides of each build-up showed a remarkable heterogeneity in the dominant cover by living organisms, and the comparison between the two build-ups highlighted an evident diversity in their taxonomic composition and structure, although crustose coralline algae (CCA) are the dominant framework builder and major autogenic ecosystem engineers at both localities, in the present as in the past millennia. Other major components of the structure are bryozoans and serpulids, and an important role is played by sediment filling. In Bogliasco, extreme climate events and major peaks of fine matrix and terrigenous grains are observed, lithologically related to the drainage basin of the Poggio creek and associated with charophyte occurrence and reduced CCA abundance. The occurrence of the rare Sporolithon ptychoides was observed both in Portofino at about 750 BCE and in Bogliasco. These Sporolithon phases are likely related to warm and humid spells punctuating the Holocene climate fluctuations in the Ligurian Sea. Because coralline algae are confirmed to be the most important habitat engineer of the Mediterranean reefs, they deserve more attention in the framework of any monitoring initiative aimed at C management and conservation.

Along the Mediterranean Sea shelf, algal reefs made of crustose coralline algae and Peyssonneliales are known as Coralligenous. It ranks among the most important ecosystems in the Mediterranean Sea because of its extent, complexity, and heterogeneity, supporting very high levels of biodiversity. Descriptive approaches for monitoring purposes are often aimed at assessing the surficial ephemeral canopy, which is sustained and controlled by the occurrence of the long-lasting rigid structure at the base. This practice led to the non-univocal definition of Coralligenous, sometimes indicated as “animal Coralligenous” because of the surficial dominance of these components. The quantitative assessment of the builders that actively build up the persistent structure through geological time is therefore a fundamental topic. We collected two discrete coralligenous samples in front of Marzamemi village (Sicily, Ionian Sea), the first from an area of a dense coralligenous cover (- 37 m) and the second one from an area with sparse build-ups (- 36 m). By using image analysis and computerized axial tomography, we distinguished and quantified the different components both on the surface and inside the framework. In both cases, our results confirm the primary role of crustose coralline algae as major builders of the Mediterranean Coralligenous, this aspect matching with the evidence from the Quaternary fossil record. We suggest that the role of encrusting calcareous red algae in the Coralligenous should be considered in conservation and management policies.

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. [ABSTRACT FROM AUTHOR]

Abstract In the framework of the Italian multidisciplinary research project "Mud volcanoes Ecosystem study - Sicily Channel", cores MV02_GC01 and MV03_GC02 were recovered from a tabular relief at 140 m water depth, to investigate the nature of such uncommon shallow seep-related morphology trough micro- and macro-paleontological, mineralogical, sedimentological and geochronological analyses. Both cores record muddy surficial sedimentation, hosting a strictly circalittoral molluskan death assemblage typical of mobile substrate, coherent with the present-day seafloor depth and environment. The core bottom recovered a biogenic framework, in which the molluskan fossil assemblage is characteristic of shallow-water, possibly infralittoral, representing a past sea level low stand. The biogenic framework shows structure and composition that are similar to present day algal reefs indicated as coralligenous build-ups. Both cores recorded the Holocene transgression. Core MV02_GC01 is longer and its basal section records cobbles and pebbles of both terrigenous and biogenic origin partially covered by a dark patina, and finely preserved Halimeda sp. fragments. The dark patina reveals a fibrous nature, often containing framboid pyrite crystals, ankerite, but no organic matter. We interpret the dark patina level as the last lowstand, possible forming in a lagoon-like paleoenvironment. Below such level, another coralligenous build-up occurs, U/Th dated to MIS 6, in agreement with the available seismic interpretation. The tabular relief lays up to 10 m above the surrounding seafloor and reveals a complex inner architecture, in which at least two generations of coralligenous build-ups shaped its geomorphological development, and the local tectonic activity contributed to its uplift. Highlights • Two cores have been collected in a tabular relief at 140 m wd south of Sicily. • Paleoecology analyses reveal sediments related to diverse climatic phases. • Bioconstruction shows features comparable to present day algal reef (coralligenous). • Coralligenous unveils a poliphasic origin of both warm and glacial stages. • Last low stand deposits are really peculiar with dark patina and recrystallization. [ABSTRACT FROM AUTHOR]

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There is abundant resource of tidal flat rich in nutritive material along the coastline of China. Except part of sludge and sandy tidal flat has been exploited for shellfish aquaculture, there is still a lot of sludge tidal flat that is rarely to be utilized. Sludge tidal flat is rich in organics, such as nitrogen and phosphorus. If the nutritive materials in sludge tidal flat are effectively combined with the multiplication process of artificial algal reef, the construction process of artificial sea-grass field will be certainly accelerated. For the effective utilization of the nutrient in sludge tidal flat, the sludge was selected as the investigated subject dug from the Shuangdao bay in Weihai City, Shandong Province. The raw materials of sludge were extracted by the way of sifting and drying, and the algal reef blocks were prepared according to 4 ratios of sludge to cement. A linear regression was adopted to analyze the elution effect of nutrient salts from the algal reef blocks, and the compression strength of reef blocks were measured as well. The results showed that among different ratios of sludge to cement, the elution rules of nitrogen and phosphorus from the reef blocks were basically accorded with the linear mode, for which the fitting degrees were all greater than 0.73. The elution effect of nutrient salts were all accorded with the release rule of slow-release fertilizer, which could continuously elute the nutritive materials containing nitrogen and phosphorus into the water to provide the necessary nutrient for the growth of algae. The sludge content of reef blocks was proportional to the elution effect of ammonium salt, and there was significant difference among 4 ratios of sludge to cement (P<0.01); the sludge content was also proportional to the elution effect of phosphate, while there was no significant difference (P>0.05), but the phosphorus contents eluted from the ratio of slug to cement of 0.9:1 and 0.7:1 were higher than the ratio of 0.5:1 and 0.3:1; in addition, the sludge content of reef blocks was inversely proportional to the compression strength of reef blocks which achieved the concrete strength standard from C15 to C25. In order to strengthen the multiplication effect of artificial algal reef, the ratio of sludge to cement can be adjusted to fulfil the demand of the ratio of nitrogen to phosphorous in water, which can increase the attachment and survival probability of algae on the artificial reef. The reef blocks in this paper have been built only by sludge and cement, which are not the usual materials of concrete. If some percentage of stone and sand are mixed into the manufacture process of these reef blocks, their strength will be promoted greatly. Therefore, the sludge tidal flat is expected to partly replace the usual concrete materials in the future during the manufacture process of artificial algal reef. This research can provide theory basis and technology reference for the application of sludge tidal flat in the manufacture and multiplication of artificial algal reef. [ABSTRACT FROM AUTHOR]

Much energy-related construction causes environmental concern. Sometimes the environmental issue is so huge that it is difficult to make a policy decision even with the assistance of traditional valuation techniques. The third natural gas receiving station at Datan, Taiwan, is one example of this. The construction would be beneficial to energy security, economic development, and particulate matter (PM) 2.5 reduction. However, it would destroy a precious algal reef, which is a habitat for endangered species, biodiversity, and a unique ecological system. Thus, we used willingness-to-pay to show the strength of both pro-energy and pro-ecology opinions specifically to help with decision-making. First, respondents were asked to choose between the gas station and the reef. Then they were asked about their willingness to pay for that choice. We then estimated parametric/nonparametric models—traditional probit, structured probit, and Turnbull—to obtain reliable estimates. We found that the per-person value for pro-gas-station respondents was higher than that for pro-reef respondents, while the percentage of pro-reef respondents was higher than the percentage of pro-gas-station respondents. These results together form a clear policy implication for this case. [ABSTRACT FROM AUTHOR]