Algal Groups Research Articles

Spatiotemporal Succession Characteristics of Algal Functional Groups and Its Impact Factors for a Typical Channel-Type Reservoir in a Southwest Mountainous Area

In order to explore the spatial and temporal variations of algal functional groups in the Zipingpu reservoir, a typical channel-type reservoir in the southwest mountainous area of China, water samples were collected from eight sections of the Zipingpu reservoir from April 2016 to March 2017.A total of 21 algal functional groups were identified as B, C, D, F, G, H1, J, L0, LM, MP, N, P, S2, T, W1, W2, X1, X2, X3, Y, and Z. Based on the analysis of the dominant degree (y > 0.02), the algal functional groups were dominated by W2, Y, L0, W1, MP, and B. The C-R-S strategy of algal growth in the Zipingpu reservoir showed that R-type was a more dominant type than the S- and C-type for the majority of the time. Peridinium (group L0, type S) was the significant algae in the Zipingpu reservoir algal bloom event in June 2016.Redundancy analysis (RDA) was used to explore the relationship between algal functional groups and environmental factors. The results showed that algal density, chlorophyll a, water temperature, and biochemical oxygen demand were the major factors influencing the spatiotemporal succession of algal functional groups across the eight sampling sections, with water temperature having the highest influence.

A gene transfer event suggests a long-term partnership between eustigmatophyte algae and a novel lineage of endosymbiotic bacteria

Rickettsiales are obligate intracellular bacteria originally found in metazoans, but more recently recognized as widespread endosymbionts of various protists. One genus was detected also in several green algae, but reports on rickettsialean endosymbionts in other algal groups are lacking. Here we show that several distantly related eustigmatophytes (coccoid algae belonging to Ochrophyta, Stramenopiles) are infected by Candidatus Phycorickettsia gen. nov., a new member of the family Rickettsiaceae. The genome sequence of Ca. Phycorickettsia trachydisci sp. nov., an endosymbiont of Trachydiscus minutus CCALA 838, revealed genomic features (size, GC content, number of genes) typical for other Rickettsiales, but some unusual aspects of the gene content were noted. Specifically, Phycorickettsia lacks genes for several components of the respiration chain, haem biosynthesis pathway, or c-di-GMP-based signalling. On the other hand, it uniquely harbours a six-gene operon of enigmatic function that we recently reported from plastid genomes of two distantly related eustigmatophytes and from various non-rickettsialean bacteria. Strikingly, the eustigmatophyte operon is closely related to the one from Phycorickettsia, suggesting a gene transfer event between the endosymbiont and host lineages in early eustigmatophyte evolution. We hypothesize an important role of the operon in the physiology of Phycorickettsia infection and a long-term eustigmatophyte-Phycorickettsia coexistence.

Impact of the invasive species Sargassum muticum (Phaeophyta) on tide pool macroalgal assemblages of northern Spain

The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt (Phaeophyta, Sargassaceae) on tide pool macroalgal assemblages of northern Spain was investigated between 2001 and 2004. Invader removal experiments were simultaneously conducted at three semi-exposed rocky-shores within a shoreline length of 200 km. Changes in the abundance of algal functional-form groups, species richness and diversity were compared between manipulated and control rock pools. Leathery macrophytes, especially Bifurcaria bifurcata, slightly increased following removal of S. muticum at 2 of the 3 studied localities. The remaining functional-form groups, diversity and species richness did not appear to be affected. Because of the heterogeneous distribution of S. muticum in northern Spain, the overall effect of the species is likely to be minimal both among localities and among pools within a locality.

Algal Colonization of Young Arctic Sea Ice in Spring

The importance of newly formed sea ice in spring is likely to increase with formation of leads in a more dynamic Arctic icescape. We followed the ice algal species succession in young ice (≤0.27 m) in spring at high temporal resolution (sampling every second day for one month in May–June 2015) in the Arctic Ocean north of Svalbard. We document the early development of the ice algal community based on species abundance and chemotaxonomic marker pigments, and relate the young-ice algal community to the communities in the under-ice water column and the surrounding older ice. The seeding source seemed to vary between algal groups. Dinoflagellates were concluded to originate from the water column and diatoms from the surrounding older ice, which emphasizes the importance of older ice as a seeding source over deep oceanic regions and in early spring when algal abundance in the water column is low. In total, 120 taxa (80 identified to species or genus level) were recorded in the young ice. The protist community developed over the study period from a ciliate, flagellate and dinoflagellate dominated community to one dominated by pennate diatoms. Environmental variables such as light were not a strong driver for the community composition, based on statistical analysis and comparison to the surrounding thicker ice with low light transmission. The photoprotective carotenoids to Chl a ratio increased over time to levels found in other high-light habitats, which shows that the algae were able to acclimate to the light levels of the thin ice. The development into a pennate diatom-dominated community, similar to the older ice, suggests that successional patterns tend towards ice-associated algae fairly independent of environmental conditions like light availability, season or ice type, and that biological traits, including morphological and physiological specialization to the sea ice habitat, play an important role in colonization of the sea ice environment. However, recruitment of ice-associated algae could be negatively affected by the ongoing loss of older ice, which acts as a seeding repository.

On the Simultaneous Identification and Quantification of Microalgae Populations Based on Fluorometric Techniques.

In this study, the phytoplankton structure of a freshwater reservoir located in central Argentina (Embalse Río Tercero) was analyzed using Beutler's method (Photosynthesis Research 72: 39-53, 2002), aiming to provide water quality control agencies with a reliable tool for early detection of algae blooms, particularly cyanobacteria. The method estimated the concentration of chlorophyll a (Chl a) contributed by individual algal groups in a real sample by fitting its fluorescence excitation spectrum to a linear combination of norm spectra of relevant algae groups. To this purpose, norm spectra for five algae genera usually found in Embalse Río Tercero, Microcystis, Chlorella, Cyclotella, Ceratium and Porphyridium, were constructed and posteriorly used to analyze samples collected in the reservoir in years 2014-2016. Results showed that the method worked well for the quick identification of the algae present in the samples, but it tended to overestimate its Chl a contents. This error was attributed to the large heterogeneity of the algal populations due to the aging of cells grown in environmental conditions.

Compact and Low-Cost Fluorescence Based Flow-Through Analyzer for Early-Stage Classification of Potentially Toxic Algae and in Situ Semiquantification.

The occurrence and intensity of (harmful) algal blooms (HABs) have increased through the years due to rapidly changing environmental conditions. At the same time, the demand for low-cost instrumentation has increased substantially, enabling the real-time monitoring and early-stage detection of HABs. To meet this challenge, we have developed a compact multi-wavelength fluorometer for less than 400 USD. This is possible by using readily available and low-cost optical and electronic components. Its modular design results in a highly versatile and flexible monitoring tool. The algae detection module enables a continuous identification and control of relevant algal groups based on their spectral characteristics with a detection limit of 10 cells per liter. Besides its usage as a benchtop module in the laboratory, the algae module has been integrated into submersible housings and applied in coastal environments. During its first in situ application in the Port of Genoa, seawater samples of mixed algal composition were used to demonstrate the successful discrimination of cyanobacteria and dinophytes as well-known toxin producing classes. Fabrication, operation, and performance as well as its first in situ application are addressed.

Complete mitochondrial genomes of six species of the freshwater red algal order Batrachospermales (Rhodophyta)

Only two mitochondrial (mt) genomes had been reported in members of the red algal order Batrachospermales, which are confined to freshwater habitats. Additional mt genomes of six representative members (Batrachospermum macrosporum, Kumanoa ambigua, K. mahlacensis, Paralemanea sp., Sheathia arcuata, and Sirodotia delicatula) were sequenced aiming to gain insights on the evolution of their mt genomes from a comparative analysis with other red algal groups. Mt genomes sequenced had the following characteristics: lengths ranging between 24,864 nt and 29,785 nt, 22 to 26 protein-coding genes, G + C contents of 21.3 to 30.7%, number of tRNA of 16 to 37, non-coding DNA from 3.8% to 14.8%. Comparative analysis revealed that mt genomes in Batrachospermales are highly conserved in terms of genome size and gene content and synteny. Phylogenetic analyses based on COI nucleotide data revealed high bootstrap support only for the genera usually recovered in the phylogenetic analyses but no support for supra-generic groups. The insertion of a group II intron carrying an ORF coding for the corresponding intron maturase interrupting the COI gene was observed in Paralamenea sp. and accounted for its larger genome in comparison to the other Batrachospermales mt genomes.

Nitrogen limitation, toxin synthesis potential, and toxicity of cyanobacterial populations in Lake Okeechobee and the St. Lucie River Estuary, Florida, during the 2016 state of emergency event.

Lake Okeechobee, FL, USA, has been subjected to intensifying cyanobacterial blooms that can spread to the adjacent St. Lucie River and Estuary via natural and anthropogenically-induced flooding events. In July 2016, a large, toxic cyanobacterial bloom occurred in Lake Okeechobee and throughout the St. Lucie River and Estuary, leading Florida to declare a state of emergency. This study reports on measurements and nutrient amendment experiments performed in this freshwater-estuarine ecosystem (salinity 0–25 PSU) during and after the bloom. In July, all sites along the bloom exhibited dissolved inorganic nitrogen-to-phosphorus ratios < 6, while Microcystis dominated (> 95%) phytoplankton inventories from the lake to the central part of the estuary. Chlorophyll a and microcystin concentrations peaked (100 and 34 μg L-1, respectively) within Lake Okeechobee and decreased eastwards. Metagenomic analyses indicated that genes associated with the production of microcystin (mcyE) and the algal neurotoxin saxitoxin (sxtA) originated from Microcystis and multiple diazotrophic genera, respectively. There were highly significant correlations between levels of total nitrogen, microcystin, and microcystin synthesis gene abundance across all surveyed sites (p < 0.001), suggesting high levels of nitrogen supported the production of microcystin during this event. Consistent with this, experiments performed with low salinity water from the St. Lucie River during the event indicated that algal biomass was nitrogen-limited. In the fall, densities of Microcystis and concentrations of microcystin were significantly lower, green algae co-dominated with cyanobacteria, and multiple algal groups displayed nitrogen-limitation. These results indicate that monitoring and regulatory strategies in Lake Okeechobee and the St. Lucie River and Estuary should consider managing loads of nitrogen to control future algal and microcystin-producing cyanobacterial blooms.

Southern Australian seaweeds: A promising resource for omega-3 fatty acids

To assess the suitability of southern-Australian macroalgae as potential marine resources for fatty acids (FA), and in particular polyunsaturated fatty acids (PUFA), analysis of 61 species, comprising of 11 Chlorophyta, 17 Phaeophyceae (Ochrophyta) and 33 Rhodophyta, was conducted. Total fatty acid (TFA) concentrations varied considerably (between 0.6 and 7.8 in % of dry weight (DW)) between species, with on average the highest concentrations being in the Phaeophyceae, then the Chlorophyta, and with the Rhodophyta recording the lowest average concentrations. Results revealed significant differences in the fatty acid profiles of the three algal groups. Most species exhibit high proportions of PUFA in their fatty acid profile and a low ratio of n-6/n-3 PUFA. These properties highlight the potential for southern-Australian macroalgae to be used for these FA in food, animal feed and nutraceutical applications.

Reduced vacuolar β-1,3-glucan synthesis affects carbohydrate metabolism as well as plastid homeostasis and structure in Phaeodactylum tricornutum

The β-1,3-glucan chrysolaminarin is the main storage polysaccharide of diatoms. In contrast to plants and green algae, diatoms and most other algal groups do not accumulate storage polysaccharides in their plastids. The diatom Phaeodactylum tricornutum possesses only a single gene encoding a putative β-1,3-glucan synthase (PtBGS). Here, we characterize this enzyme by expressing GFP fusion proteins in P. tricornutum and by creating and investigating corresponding gene silencing mutants. We demonstrate that PtBGS is a vacuolar protein located in the tonoplast. Metabolite analyses of two mutant strains with reduced amounts of PtBGS reveal a reduction in their chrysolaminarin content and an increase of soluble sugars and lipids. This indicates that carbohydrates are shunted into alternative pathways when chrysolaminarin production is impaired. The mutant strains show reduced growth and lower photosynthetic capacities, while possessing higher photoprotective abilities than WT cells. Interestingly, a strong reduction in PtBGS expression also results in aberrations of the usually very regular thylakoid membrane patterns, including increased thylakoid thickness, reduced numbers of thylakoids per plastid, and increased numbers of lamellae per thylakoid stack. Our data demonstrate the complex intertwinement of carbohydrate storage in the vacuoles with carbohydrate metabolism, photosynthetic homeostasis, and plastid morphology.

Spatial differences in dissolved silicon utilization in Lake Baikal, Siberia: Examining the impact of high diatom biomass events and eutrophication

AbstractRecent research has highlighted how Lake Baikal, Siberia, has responded to the direct and indirect effects of climate change (e.g., ice‐cover duration), nutrient loading, and pollution, manifesting as changes in phytoplankton/zooplankton populations, community structure, and seasonal succession. Here, we combine and compare analyses of chlorophyll a (an estimate of total algal biomass), carotenoid pigments (biomarkers of algal groups), and lake water silicon isotope geochemistry (δ30SiDSi) to differentiate spatial patterns in dissolved silicon (DSi) uptake at Lake Baikal. A total of 15 sites across the three basins (south, central, and north) of Lake Baikal were sampled in August 2013 along a depth gradient of 0–180 m. Strong, significant correlations were found between vertical profiles of photic zone DSi concentrations and δ30SiDSi compositions (r = −0.81, p &lt; 0.001), although these are strongest in the central basin aphotic zone (r = −0.98, p &lt; 0.001). Data refute the hypothesis of DSi uptake by picocyanobacteria. Algal biomass profiles and high surface δ30SiDSi compositions suggest greater productivity in the south basin and more oligotrophic conditions in the north basin. δ30SiDSi signatures are highest at depth (20 m) in central basin sites, indicating greater (10–40%) DSi utilization at deep chlorophyll maxima. DSi limitation occurs in the pelagic central basin, probably reflecting a high diatom biomass bloom event (Aulacoseira baicalensis). Meanwhile in the more hydrologically restricted, shallow Maloe More region (central basin), both high δ30SiDSi compositions and picocyanobacteria (zeaxanthin) concentrations, respectively point to the legacy of an “Aulacoseira bloom year” and continuous nutrient supply in summer months (e.g., localized eutrophication).

Could the extreme meteorological events in Lake Maggiore watershed determine a climate-driven eutrophication process?

Lake Maggiore has reached a stable oligotrophic status after a recovery process from mesotrophy that began in the early 1980s. However, the most recent phytoplankton and water chemistry data seem to indicate that various changes are taking place, including a slight increase in TP values, and almost regular blooms have occurred since 2005. Meteoclimatic data collected over the last few decades in the Lake Maggiore watershed highlight an increase in the frequency of extreme rainfall events. Here, for the period 2000–2013, we analyse the relationships between the phytoplankton dynamics and selected extreme precipitation events, in order to evaluate the possible role of rainfall in affecting the nutrient availability and phytoplankton dynamics. Among the algal groups, cyanobacteria showed the strongest relationship with the precipitation pattern, particularly on a short-term temporal scale. Our results support the hypothesis that rainfall may lead to a short-term increase in nutrients that stimulate the growth of phytoplankton and the development of blooms in summer, when epilimnetic waters are usually nutrient depleted. The almost regular cyanobacterial blooms recorded in Lake Maggiore since 2005 can be interpreted as a response to changing precipitation patterns and therefore as a sign of climate-induced eutrophication.

Analysis and modeling of algal blooms in the Nakdong River, Korea

The purpose of this study is to improve the prediction accuracy of algal blooms in the Nakdong River, Korea, to support improved management practices. To improve algal bloom predictions, it is necessary to consider the microbiological characteristics of algal groups. Therefore, Korean governmental data, including water quality, flow rate, and meteorological data, over 12 years (2004–2015) were analyzed to characterize chlorophyll a (Chl-a) concentration dynamics in the Nakdong River, as the primary indicator of algae. The correlation between water temperature and Chl-a concentration differed by region at the study site. While a positive correlation (R = 0.63) was found in the relatively clean (i.e., mesotrophic) upstream area, a negative correlation (R = −0.51) was found in the more eutrophic downstream area. These results indicate that nutrients are a dominant factor of algal blooms in mesotrophic upstream areas, but other factors may have greater impacts in eutrophic downstream areas. Moreover, the dominance of different algal groups differed spatially and temporally at the study site. The three-dimensional hydrodynamics and water quality modeling-capable Environmental Fluid Dynamics Code model was applied to represent the hydrodynamics and kinetics of water quality variables, including Chl-a. Four statistics, the coefficient of determination (R2), Nash–Sutcliffe model efficiency (ME), percentage model bias (Pbias), and cost function (CF), were used to evaluate the model prediction accuracy against field observation data. Compared to the case in which only a single algal group was modeled, modeling multiple algal groups together improved the R2, ME, Pbias, and CF values from 0.25 to 0.50, 0.15 to 0.50, 30.43 to 4.98, and 0.56 to 0.48, respectively. The degree of improvement in the model prediction accuracy was greater for more eutrophic regions at the study site. These results show that there should be greater focus on studying multiple algal groups together when modeling algal bloom predictions to support the development of alternative management practices.

Consortial brown tide − picocyanobacteria blooms in Guantánamo Bay, Cuba

A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml−1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35–36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the short-lived duration of the brown tide bloom in Guantánamo Bay.

Algological and Mycological Characterization of Soils under Pine and Birch Forests in the Pasvik Reserve

The structure of algological and mycological complexes in Al–Fe-humus podzols (Albic Podzols) under pine and birch forests of the Pasvik Reserve is characterized. The number of micromycetes is higher in more acid soils of the pine forest, while the species diversity is greater under the birch forest. The genus Penicillium includes the largest number of species. The greatest abundance and occurrence frequency are typical for Penicillium spinulosum, P. glabrum, and Trichoderma viride in pine forest and for Umbelopsis isabellina, Mucor sp., Mortierella alpinа, P. glabrum, Aspergillus ustus, Trichoderma viride, and T. koningii in birch forest. Cyanobacteria–algal cenoses of the investigated soils are predominated by green algae. Soils under birch forest are distinguished by a greater diversity of algal groups due to the presence of diatoms and xanthophytes. Species of frequent occurrence are represented by Pseudococcomyxa simplex and Parietochloris alveolaris in soils of the pine forest and by Tetracystis cf. aplanospora, Halochlorella rubescens, Pseudococcomyxa simplex, Fottea stichococcoides, Klebsormidium flaccidum, Hantzschia amphioxys, Microcoleus vaginatus, and Aphanocapsa sp. in soils under birch forest

Environmental variables, algal pigments and phytoplankton in the Atlantic Ocean off the coast of Badagry, Lagos

The phytoplankton diversity, environmental variables and algal pigments of the Atlantic Ocean off the coast of Badagry, Lagos were investigated for twelve months between May 2015 and April 2016. The water chemistry characteristics reflected sea water conditions. At the two stations, the range of values recorded for some physico-chemical variables were rainfall (4.1 - 449.3mm), air temperature (23 - 30°C), water temperature (25-31°C), salinity (26.6 - 31.81‰), pH (7.9 - 8.12) and total dissolved solids (26980.1–32900.1mg/L), The phytoplankton diversity consisted of 44 species belonging to three main algal groups namely: 30 species of diatoms (Bacillariophyta) making up 80.49%, five species of blue-green algae (Cyanophyta) making up 13.57% and nine species of dinoflagellate (Dinophyta) accounting for the remaining 5.94%.. Notable species were Coscinodiscus centralis, Coscinodiscus radiatus, Thalassionema nitzschioides and Thalassionema longissima (Diatoms) and a blue-green algae Trichodesmium thiebautii. Nitrate was the key limiting nutrient with regards to algal pigment concentration. The values for the correlation of chlorophyll a (r=0.590, p <0.05), chlorophyll b (r=0.496, p<0.01) and phaeophytin a (r=0.286) with nitrate were significantly positively correlated. Hence, Nitrate is the trigger nutrient for increased algal pigments concentration in the study area.Keywords: Sea, Lagoon, neritic, diatoms, physico-chemical, phytochemicals

Plastid phylogenomics with broad taxon sampling further elucidates the distinct evolutionary origins and timing of secondary green plastids

Secondary plastids derived from green algae occur in chlorarachniophytes, photosynthetic euglenophytes, and the dinoflagellate genus Lepidodinium. Recent advances in understanding the origin of these plastids have been made, but analyses suffer from relatively sparse taxon sampling within the green algal groups to which they are related. In this study we aim to derive new insights into the identity of the plastid donors, and when in geological time the independent endosymbiosis events occurred. We use newly sequenced green algal chloroplast genomes from carefully chosen lineages potentially related to chlorarachniophyte and Lepidodinium plastids, combined with recently published chloroplast genomes, to present taxon-rich phylogenetic analyses to further pinpoint plastid origins. We integrate phylogenies with fossil information and relaxed molecular clock analyses. Our results indicate that the chlorarachniophyte plastid may originate from a precusor of siphonous green algae or a closely related lineage, whereas the Lepidodinium plastid originated from a pedinophyte. The euglenophyte plastid putatively originated from a lineage of prasinophytes within the order Pyramimonadales. Our molecular clock analyses narrow in on the likely timing of the secondary endosymbiosis events, suggesting that the event leading to Lepidodinium likely occurred more recently than those leading to the chlorarachniophyte and photosynthetic euglenophyte lineages.

The Chlorophytes of Curaçao (Caribbean): a revised checklist for the south-west coast

Abstract The global trend of unprecedented losses in coral reefs is particularly striking in the Caribbean, where dense algal assemblages are commonly replacing corals. So far, hardly anything is known about the ecology of the dominant algal groups. The present study compiled records of Chlorophytes from nine studies in the shallow reefs of Curaçao in the years preceding the onset of coral reef decline (1908–1978) and compared them with records from three recent (2007–2009) expeditions conducted at the same and nearby study locations along the south-west coast of the island. A total of 107 species were encountered, including seven new records for Curaçao (Anadyomene saldanhae, Bryopsis hypnoides, Chaetomorpha minima, Derbesia fastigiata, Ulva flexuosa subsp. paradoxa, Ulvella scutata and Ulvella lens). Sampled material revealed a higher species number during the dry seasons than during the wet seasons, indicating a seasonal variation in algal growth. Most species grew on hard substratum or were epibiotic, and 13 species were found growing on more than one substratum. Comparisons with earlier studies suggest an extension in depth range for nine species. The present work provides a comprehensive overview of the distribution of Chlorophytes of the island and can serve as an important baseline for further research on coral reef ecosystem changes.

Tepoztequiella rhizoidea gen. et sp. nov. (Solieriaceae, Rhodophyta) from the Yucatan Peninsula, Mexico

:Molecular methods have greatly aided in discovering new diversity in many cryptic algal groups. Molecular-assisted species discovery has focused morphological analyses on previously overlooked taxa, leading to a better understanding of diversity and evolutionary patterns. The Yucatan Peninsula, as a junction of North and South American Atlantic floras, is very diverse and, while a well-explored area, continues to reveal new species. Our studies in this area have revealed a new cylindrical member of the Solieriaceae. Based on COI-5P, rbcL and RuBisCo spacer sequences, we show that this entity is phylogenetically unique. Its position in phylogenetic analyses, combined with morphological characters and the genetic divergence from other species and genera within the family, strongly supports the establishment of Tepoztequiella rhizoidea gen. & sp. nov. The diagnostic character of T. rhizoidea is the presence of many rhizoids arising from medullary filaments and from the cells of the inner cortex.

Effects of herbivores, wave exposure and depth on benthic coral communities of the Easter Island ecoregion

The Easter Island ecoregion includes Rapa Nui (Easter Island; RN), with a human population of ~5600, and the uninhabited Salas y Gómez (SyG). Although the culture and terrestrial ecology of RN have been well studied, we know little about the marine environment of these islands, particularly the interplay among herbivores, algae, and corals, and how coral reef communities differ between islands, by wave energy exposure, and between depths. To address the potential roles of herbivores, wave-energy exposure, and depth on the sessile benthic communities, we examined herbivorous fish biomass, sea urchin (Diadema savignyi) density, and algal and coral cover to identify patterns and relationships among these groups. We found significant differences between islands. For example, turf and macroalgae were nearly absent from SyG, whereas D. savignyi density and Kyphosus sandwicensis biomass were ~28- and ~3-fold greater respectively at SyG. Benthic cover of coral and algae and density of D. savignyi significantly differed among levels of wave exposure, especially between wave-protected stations and semi-exposed and exposed stations. Likewise, community structure significantly differed at protected stations. Concordant patterns between herbivores and algae were observed. Therefore, herbivores and wave energy likely play important roles in structuring these benthic communities, especially for algal groups.