Modeling the mutualistic interactions between tubeworms and microbial consortia

The deep-sea vestimentiferan tubeworm Lamellibrachia luymesi forms large aggregations at hydrocarbon seeps in the Gulf of Mexico that may persist for over 250 y. Here, we present the results of a diagenetic model in which tubeworm aggregation persistence is achieved through augmentation of the supply of sulfate to hydrocarbon seep sediments. In the model, L. luymesi releases the sulfate generated by its internal, chemoautotrophic, sulfide-oxidizing symbionts through posterior root-like extensions of its body. The sulfate fuels sulfate reduction, commonly coupled to anaerobic methane oxidation and hydrocarbon degradation by bacterial–archaeal consortia. If sulfate is released by the tubeworms, sulfide generation mainly by hydrocarbon degradation is sufficient to support moderate-sized aggregations of L. luymesi for hundreds of years. The results of this model expand our concept of the potential benefits derived from complex interspecific relationships, in this case involving members of all three domains of life.     

Twelve microsatellites for two deep sea polychaete tubeworm species,Lamellibrachia luymesi and Seepiophila jonesi,from the Gulf of Mexico

The vestimentiferan tubeworms Lamellibrachia luymesi and Seepiophila jonesi are found at hydrocarbon seeps in the Gulf of Mexico. Primers for polymorphic microsatellite loci were developed from genomic libraries of L. luymesi (five loci) and from S. jonesi tissue (eight loci) and were used to screen individuals collected from nine northern Gulf of Mexico hydrocarbon seep sites. Loci had from four to more than 50 alleles with high expected levels of heterozygosity. Cross‐species amplification, tested on seven vestimentiferan species including both hydrothermal vent and cold seep species, was generally strong in similar species but weak in more genetically distant species.     

Depth-dependent gene flow in Gulf of Mexico cold seep Lamellibrachia tubeworms (Annelida,Siboglinidae)

Lamellibrachia vestimentiferan tubeworms form aggregations at hydrocarbon cold seeps in the deep Gulf of Mexico (GoM), creating structures that provide living space for other fauna. In the GoM, three Lamellibrachia taxa vary in morphology and depth ranges: Lamellibrachia luymesi (300–950 m), Lamellibrachia sp. 1 (950–2,604 m), and Lamellibrachia sp. 2 (1,175–3,304 m). While Lamellibrachia sp. 2 is consistently identified as a separate species, L. luymesi and sp. 1 cannot be discriminated using barcoding markers cytochrome oxidase subunit 1 (COI) and large ribosomal subunit rDNA (16S). To determine if limited gene flow was a factor in the formation of these taxa, we employed more quickly evolving markers, including mitochondrial cytochrome B (CYTB), hemoglobin subunit B2 intron (HbB2i), and six polymorphic microsatellites; microsatellites were amplified across 45 L. luymesi and sp. 1 individuals. Additionally, we used microsatellites to ask whether populations of Lamellibrachia sp. 1 and sp. 2 show evidence of significant structure. Despite a lack of resolution seen with CYTB and HbB2i, L. luymesi and sp. 1 form genetically differentiated clusters at the cross-amplified microsatellites. Furthermore, we find no evidence for population structure for either Lamellibrachia sp. 1 or sp. 2 across the GoM.     

Alternate unstable states: Convergent paths of succession in hydrocarbon-seep tubeworm-associated communities

Previous studies have shown clear, predictable successional trends in habitat characteristics and community structure in tubeworm aggregations at 3 similar hydrocarbon-seep sites on the central upper Louisiana slope of the Gulf of Mexico. In this study, we examine these trends in quantitative community collections from 7 additional hydrocarbon-seep sites widely distributed in the northern Gulf of Mexico. The relative proportions and sizes of Lamellibrachia luymesi and Seepiophila jonesi in tubeworm aggregations were similar at new and central sites, though S. jonesi dominated some collections from new sites, a situation not previously observed at central sites. In general, sulfide declined with increasing aggregation age (average size of tubeworms), but there was more variability in this trend at the new sites. Tubeworm-associated community composition was similar at new and central sites, with only a few rare species collected at the new sites for the first time. The most significant differences in the communities at new sites were the lower relative abundance of various gastropod species, and the absence of gastropods from collections made at the Viosca Knoll site. This community type was largely restricted to young aggregations at new sites that were more isolated from other tubeworm aggregations and consisted of higher proportions of S. jonesi. As succession proceeds from young to old aggregations, many of the previously described processes were apparent at the new sites including a reduction in biomass and a shift in trophic structure from endemic primary consumers to non-endemic higher order predators. Regardless of community composition in young aggregations, succession converges on similar late-stage community types.     

High‐contiguity genome assembly of the chemosynthetic gammaproteobacterial endosymbiont of the cold seep tubeworm Lamellibrachia barhami

Symbiotic relationships between vestimentiferan tubeworms and chemosynthetic Gammaproteobacteria build the foundations of many hydrothermal vent and hydrocarbon seep ecosystems in the deep sea. The association between the vent tubeworm Riftia pachyptila and its endosymbiont Candidatus Endoriftia persephone has become a model system for symbiosis research in deep‐sea vestimentiferans, while markedly fewer studies have investigated symbiotic relationships in other tubeworm species, especially at cold seeps. Here we sequenced the endosymbiont genome of the tubeworm Lamellibrachia barhami from a cold seep in the Gulf of California, using short‐ and long‐read sequencing technologies in combination with Hi‐C and Dovetail Chicago libraries. Our final assembly had a size of ~4.17 MB, a GC content of 54.54%, 137X coverage, 4153 coding sequences, and a CheckM completeness score of 97.19%. A single scaffold contained 99.51% of the genome. Comparative genomic analyses indicated that the L. barhami symbiont shares a set of core genes and many metabolic pathways with other vestimentiferan symbionts, while containing 433 unique gene clusters that comprised a variety of transposases, defence‐related genes and a lineage‐specific CRISPR/Cas3 system. This assembly represents the most contiguous tubeworm symbiont genome resource to date and will be particularly valuable for future comparative genomic studies investigating structural genome evolution, physiological adaptations and host‐symbiont communication in chemosynthetic animal‐microbe symbioses.     

Methane-flux-dependent lateral faunal changes in a Late Cretaceous chemosymbiotic assemblage from the Nakagawa area of Hokkaido, Japan

A Late Cretaceous carbonate body (2 m in maximum diameter) surrounded by clastic rocks, recently discovered in the Nakagawa area (Hokkaido, Japan), is interpreted as a methane‐seep deposit, on the basis of negative carbon isotopic composition (as low as ?43.5‰), variable sulphide sulphur isotopic composition, high carbonate content, and in situ fractures. It most likely formed owing to methane‐bearing pore‐water diffusion. We estimate that the concentration of methane decreased toward the margin of the carbonate body, and that only small carbonate concretions were precipitated at a certain distance from the methane‐seep centre. These spatial characteristics coincide well with the observed pattern of faunal distribution. The gastropod‐dominated association (indeterminate abyssochrysids and ataphrids and the acmaeid limpet Serradonta sp. are most common) co‐occurs with lucinid and thyasirid bivalves (Thyasira sp., Myrtea sp., and Miltha sp.), and was found within and just above the methane‐derived carbonate body. Acharax and Nucinella (solemyoid bivalves) are more typical of the peripheral part of the methane‐influenced sediments. We suggest that this pattern of faunal distribution reflects the decreasing concentration of methane and apparently also hydrogen sulphide when moving from the centre of discharge toward the periphery of the methane seep.     

Dynamics of cell proliferation and apoptosis reflect different life strategies in hydrothermal vent and cold seep vestimentiferan tubeworms

Deep-sea vestimentiferan tubeworms, which live in symbiosis with bacteria, exhibit different life strategies according to their habitat. At unstable and relatively short-lived hydrothermal vents, they grow extremely fast, whereas their close relatives at stable and long-persisting cold seeps grow slowly and live up to 300 years. Growth and age differences are thought to occur because of ecological and physiological adaptations. However, the underlying mechanisms of cell proliferation and death, which are closely linked to homeostasis, growth, and longevity, are unknown. Here, we show by immunohistochemical and ultrastructural cell cycle analyses that cell proliferation activities of the two species studied are higher than in any other characterized invertebrate, being only comparable with tumor and wound-healing processes. The slow growth in Lamellibrachia luymesi from cold seeps results from balanced activities of proliferation and apoptosis in the epidermis. In contrast, Riftia pachyptila from hydrothermal vents grows fast because apoptosis is down-regulated in this tissue. The symbiont-housing organ, the trophosome, exhibits a complex cell cycle and terminal differentiation pattern in both species, and growth is regulated by proliferation. These mechanisms have similarities to the up- and down-regulation of proliferation or apoptosis in various types of tumor, although they occur in healthy animals in this study, thus providing significant insights into the underlying mechanisms of growth and longevity. Financial support was provided by the Austrian Science Foundation (FWF; grants to M.B.), a DOC scholarship from the Austrian Academy of Science (to B.P.), and grants from the US National Science Foundation (to C.R. Fisher).     

Enantioselective recognition of carboxylic acids by novel fluorescent triazine‐based thiazoles

Hydrogen bonding and π‐π interactions take special part in the enantioselectivity task. In this regard, because of having both hydrogen acceptor and hydrogen donor groups, melamine derivatives become more of an issue for enantioselectivity. In the light of such information, triazine‐based chiral, fluorescence active novel thiazole derivatives L1 and L2 were designed and synthesized from (S)‐(?)‐2‐amino‐1‐butanol and (1S,2R)‐(+)‐2‐amino‐1,2‐diphenylethanol. The structural establishment of these compounds was made by spectroscopic methods such as FTIR, ¹H, and ¹³C NMR. While the solution of these compounds in DMSO did not show any fluorescence emission, it was observed that the emission increased 44‐fold for L1 and 55‐fold for L2 in 95% water, similar to the aggregation‐induced emission (AIE) characterized compounds. In this regard, enantioselective capabilities of these compounds against carboxylic acids were tested, and in experiments carried out at a ratio of 40/60 DMSO/H₂O, it was determined that R‐2ClMA increased the fluorescence emission of L1 chiral receptor by 2.59 times compared to S‐isomer.     

The palaeoecology of the latest Jurassic–earliest Cretaceous hydrocarbon seep carbonates from Spitsbergen,Svalbard

Latest Jurassic–earliest Cretaceous hydrocarbon seeps from Spitsbergen, Svalbard, are known to contain unusual fauna, lacking most of the species characteristic for roughly coeval seep deposits. This study summarizes and analyses the fauna from 16 seep carbonate bodies from Spitsbergen to explain its composition. The seeps formed in a shallow epicontinental sea with widespread deposition of fine‐grained, organic‐rich sediments. They are spread over a relatively large area and are positioned roughly in the same interval, indicating seepage over extensive areas of the palaeo‐Barents Sea. The seep fauna is very species rich and with low dominance, comprising 54 species, with a composition similar to that of Jurassic–Cretaceous normal‐marine environments of other Boreal seas. Seep‐restricted fauna is not abundant and is represented by four species only. Hokkaidoconchids and possible siboglinid worm tubes characteristic for high sulphide fluxes are rare. Apart from seep‐restricted sulphide‐mining lucinid and thyasirid bivalves, chemosymbiosis was also a source of nourishment for background solemyid and nucinellid bivalves, all of which take sulphide from infaunal sources. This all suggests a relatively weak sulphide flux. The high diversity and low dominance of the fauna and significant richness and abundance of background species is typical for shallow water seeps.     

Anaerobic methanotrophic community of a 5346‐m‐deep vesicomyid clam colony in the Japan Trench

Vesicomyidae clams harbor sulfide‐oxidizing endosymbionts and are typical members of cold seep communities where active venting of fluids and gases takes place. We investigated the central biogeochemical processes that supported a vesicomyid clam colony as part of a locally restricted seep community in the Japan Trench at 5346 m water depth, one of the deepest seep settings studied to date. An integrated approach of biogeochemical and molecular ecological techniques was used combining in situ and ex situ measurements. In sediment of the clam colony, low sulfate reduction rates (maximum 128 nmol mL^?1 day^?1) were coupled to the anaerobic oxidation of methane. They were observed over a depth range of 15 cm, caused by active transport of sulfate due to bioturbation of the vesicomyid clams. A distinct separation between the seep and the surrounding seafloor was shown by steep horizontal geochemical gradients and pronounced microbial community shifts. The sediment below the clam colony was dominated by anaerobic methanotrophic archaea (ANME‐2c) and sulfate‐reducing Desulfobulbaceae (SEEP‐SRB‐3, SEEP‐SRB‐4). Aerobic methanotrophic bacteria were not detected in the sediment, and the oxidation of sulfide seemed to be carried out chemolithoautotrophically by Sulfurovum species. Thus, major redox processes were mediated by distinct subgroups of seep‐related microorganisms that might have been selected by this specific abyssal seep environment. Fluid flow and microbial activity were low but sufficient to support the clam community over decades and to build up high biomasses. Hence, the clams and their microbial communities adapted successfully to a low‐energy regime and may represent widespread chemosynthetic communities in the Japan Trench. In this regard, they contributed to the restricted deep‐sea trench biodiversity as well as to the organic carbon availability, also for non‐seep organisms, in such oligotrophic benthic environment of the dark deep ocean.     

Marenzelleria cf. viridis and the sulphide regime

To find out how the polychaete Marenzelleria cf. viridis could spread successfully into the habitat of the Darss-Zingst Bodden Chain, one important environmental factor for sediment dwelling animals was examined: hydrogen sulphide. To investigate the stress of this environmental factor, hydrogen sulphide was continuously examined in the pore water of the sediment and burrows of M. cf. viridis. Metabolic activity was recorded by direct and indirect calorimetry. Depending on water temperature, organic matter content of the sediment and salinity, the sulphide concentration in the pore water varied between 1.5 and 4.2 mmol l^-1 being high during summer and in winter when the sediment and overlying water was ice covered. In microcosm experiments water of M. cf. viridis-burrows showed variations in sulphide between 145 and 210 µmol l^-1 but pore water concentration was much higher (6.5 mmol l^-1). In the presence of oxygen animals exhibited an accelerated metabolic rate which was met by a fully aerobic metabolism at Po₂ of 20 to 7.5 kPa and sulphide concentration of 215–245 µmol l^-1. When oxygen is absent the heat production was only slightly elevated (103%) when compared to the anoxic control. The elevated heat production of the animals during sulphide exposure and oxygen may be due to detoxification processes. In this case thiosulphate is formed probably via mitochondrial oxidation and therefore may account for additional ATP-gain.     

DOES MATE LIMITATION IN SELF‐INCOMPATIBLE SPECIES PROMOTE THE EVOLUTION OF SELFING? THE CASE OF LEAVENWORTHIA ALABAMICA

Genetic diversity at the S‐locus controlling self‐incompatibility (SI) is often high because of negative frequency‐dependent selection. In species with highly patchy spatial distributions, genetic drift can overwhelm balancing selection and cause stochastic loss of S‐alleles. Natural selection may favor the breakdown of SI in populations with few S‐alleles because low S‐allele diversity constrains the seed production of self‐incompatible plants. We estimated S‐allele diversity, effective population sizes, and migration rates in Leavenworthia alabamica, a self‐incompatible mustard species restricted to discrete habitat patches in rocky glades. Patterns of polymorphism were investigated at the S‐locus and 15 neutral microsatellites in three large and three small populations with 100‐fold variation in glade size. Populations on larger glades maintained more S‐alleles, but all populations were estimated to harbor at least 20 S‐alleles, and mate availabilities typically exceeded 0.80, which is consistent with little mate limitation in nature. Estimates of the effective size (N_e) in each population ranged from 600 to 1600, and estimated rates of migration (m) ranged from 3 × 10⁻⁴ to nearly 1 × 10⁻³. According to theoretical models, there is limited opportunity for genetic drift to reduce S‐allele diversity in populations with these attributes. Although pollinators or resources limit seed production in small glades, limited S‐allele diversity does not appear to be a factor promoting the incipient breakdown of SI in populations of this species that were studied.     

南海Formosa冷泉区沉积物微生物多样性与分布规律研究

【目的】当前对全球冷泉生态系统微生物生态学研究显示，冷泉生态系统中主要微生物类群为参与甲烷代谢的微生物，它们的分布差异与所处冷泉区生物地球化学环境密切相关。但在冷泉区内也存在环境因子截然不同的生境，尚缺乏比较冷泉区内小尺度生境间微生物多样性和分布规律的研究。本研究旨在分析南海Formosa冷泉区内不同生境间微生物多样性差异，完善和理解不同环境因子对冷泉内微生物群落结构的影响。【方法】对采集自南海Formosa冷泉区不同生境(黑色菌席区、白色菌席区和碳酸盐岩区)沉积物样本中古菌和细菌16S rRNA基因进行测序，结合环境因子，比较微生物多样性差异，分析环境因子对微生物分布的影响。【结果】发现在Formosa冷泉内的不同生境中，甲烷厌氧氧化古菌(anaerobic methanotrophic archaea,ANME)是主要古菌类群，占古菌总体相对丰度超过70%；在菌席区ANME-1b和ANME-2a/b是主要ANME亚群，碳酸盐岩区则是ANME-1b。硫酸盐还原菌(sulfate-reducing bacteria,SRB)和硫氧化菌(sulfur-oxidizing bacteria...     

Increased Abundance of Gallionella spp., Leptothrix spp. and Total Bacteria in Response to Enhanced Mn and Fe Concentrations in a Disturbed Southern Appalachian High Elevation Wetland

The Sorrento wetland hosts several Fe- and Mn-rich seeps that are reported to have appeared after the area was disturbed by recent attempts at development. Culture-independent and culture-based analyses were utilized to characterize the microbial community at the main site of the Fe and Mn seep. Several bacteria capable of oxidizing Mn(II) were isolated, including members related to the genera Bacillus, Lysinibacillus, Pseudomonas, and Leptothrix, but none of these were detected in clone libraries. Most probable number assays demonstrated that seep and wetland sites contained higher numbers of culturable Mn-oxidizing microorganisms than an upstream reference site. When compared with quantitative real time PCR (qPCR) assays of total bacteria, MPN analyses indicated that less than 0.01% of the total population (estimated around 10⁹ cells/g) was culturable. Light microscopy and fluorescence in situ hybridization (FISH) images revealed an abundance of morphotypes similar to Fe- and Mn-oxidizing Leptothrix spp. and Gallionella spp. in seep and wetland sites. FISH allowed identification of Leptothrix-type sheath-forming organisms in seep samples but not in reference samples. Gallionella spp. and Leptothrix spp. cells numbers were estimated using qPCR with a novel primer set that we designed. Results indicated that numbers of Gallionella, Leptothrix or total bacteria were all significantly higher at the seep site relative to the reference site (where Gallionella was below detection). Interestingly, numbers of Leptothrix in the seep site were estimated at only 10⁷ cells/g and were not statistically different in the late summer versus the late winter, despite dramatic changes in sheath abundance (as indicated by microscopy). qPCR also indicated that Gallionella spp. may represent up to 10% (3 × 10⁸ cells/g) of the total bacteria in seep samples. These data corroborate clone library data from samples taken in October 2008, where 11 SSU rRNA sequences related to Gallionella spp. were detected out of 77 total sequences (roughly 10–15%), and where Leptothrix sequences were not detected. Analysis of this SSU rRNA clonal library revealed that a diverse microbial community was present at seep sites. At a 3% difference cutoff, 30 different operational taxonomic units were detected out of 77 sequences analyzed. Dominant sequence types clustered among the beta- and gamma- Proteobacteria near sequences related to the genera Ideonella, Rhodoferax, Methylotenera, Methylobacter, and Gallionella. Overall, results suggest that high metal concentrations at the seep sites have enriched for Fe- and Mn-oxidizing bacteria including organisms related to Gallionella and Leptothrix species, and that members of these genera coexist within a diverse microbial community.     

The social elite: Habitat heterogeneity,complexity and quality in granite inselbergs influence patterns of aggregation in Egernia striolata (Lygosominae: Scincidae)

Habitat heterogeneity, structural complexity and habitat quality are key features of the environment that drive species' distribution and patterns of biological organization. Traditionally, pattern‐based studies have focused on faunal responses to biological systems. However, the influence of non‐biological environments such as insular rock outcrops on patterns of vertebrate distribution is conceivably as important, but has received less attention. Granite inselbergs are a naturally heterogeneous and spatially‐limited habitat. As such, they provide an opportunity for investigating whether environmental attributes influence social behaviour in animals that use these kinds of habitat, particularly lizards that are well adapted to saxicoline environments. We applied ecological theory to investigate the influence of habitat heterogeneity, structural complexity and habitat quality on patterns of home‐site occupancy in the crevice skink Egernia striolata (Lygosominea: Scincidae) from insular granite outcrops located within fragmented agricultural landscapes. We compared home‐site occupancy among solitary juveniles, solitary adults and lizard aggregations. We found significant differences in home‐site occupancy between aggregations and solitary lizard outcrop attributes measured at multiple spatial scales. The probability of a home‐site being occupied by an aggregation increased where large rock masses were present, on northern aspects near the core of the outcrop and in structurally variegated landscapes. Significantly more aggregations occupied home‐sites surrounded by high boulder cover and crevice microhabitat. We provide evidence that geophysical attributes of granite inselbergs and landscape context can influence patterns of lizard aggregation. Thus, we clearly document the environmental correlations of variability in sociality among subpopulations of Egernia striolata.     

Restriction to large‐scale gene flow vs. regional panmixia among cold seep Escarpia spp. (Polychaeta,Siboglinidae)

The history of colonization and dispersal in fauna distributed among deep‐sea chemosynthetic ecosystems remains enigmatic and poorly understood because of an inability to mark and track individuals. A combination of molecular, morphological and environmental data improves understanding of spatial and temporal scales at which panmixia, disruption of gene flow or even speciation may occur. Vestimentiferan tubeworms of the genus Escarpia are important components of deep ‐sea cold seep ecosystems, as they provide long‐term habitat for many other taxa. Three species of Escarpia, Escarpia spicata [Gulf of California (GoC)], Escarpia laminata [Gulf of Mexico (GoM)] and Escarpia southwardae (West African Cold Seeps), have been described based on morphology, but are not discriminated through the use of mitochondrial markers (cytochrome oxidase subunit 1; large ribosomal subunit rDNA, 16S; cytochrome b). Here, we also sequenced the exon‐primed intron‐crossing Haemoglobin subunit B2 intron and genotyped 28 microsatellites to (i) determine the level of genetic differentiation, if any, among the three geographically separated entities and (ii) identify possible population structure at the regional scale within the GoM and West Africa. Results at the global scale support the occurrence of three genetically distinct groups. At the regional scale among eight sampling sites of E. laminata (n = 129) and among three sampling sites of E. southwardae (n = 80), no population structure was detected. These findings suggest that despite the patchiness and isolation of seep habitats, connectivity is high on regional scales.     

Comparative hydrocarbon utilization by hydrophobic and hydrophilic variants of Pseudomonas aeruginosa

Aims: To investigate hydrocarbon degradation by hydrophobic, hydrophilic and parental strains of Pseudomonas aeruginosa. Methods and Results: Partitioning of hydrocarbon‐degrading P. aeruginosa strain in a solvent/aqueous system yielded hydrophobic and hydrophilic fractions. Exhaustive partitioning of aqueous‐phase cells yielded the hydrophilic variants (L), while sequential fractionation of the hydrophobic phase cells yielded successive fractions exhibiting increasing cell‐surface hydrophobicity (CSH). In hydrocarbon adherence assays (bacterial attachment to hydrocarbon), L had a value of 20%, which increased from 61·7% in first hydrophobic fraction (H₁) to 72·2% in the third (H₃). Crude oil degradation by L was 70%, but increased from 82% in H₁ to 93% in H₃. L variant produced most exopolysaccharides and reduced surface tension from about 73 to 49 mN m^?1. Rhamnolipid production was highest in L, but was not detected in all crude oil cultures. Conclusions: Hydrophobic subpopulations of hydrocarbon‐degrading P. aeruginosa exhibited greater hydrocarbon‐utilizing ability than hydrophilic ones, or the parental strain. Significance and Impact of the Study: Results demonstrate that a population of P. aeruginosa consists of cells with different CSH which affect hydrocarbon utilization. This potentially provides the population with the capacity to utilize different hydrophobic substrates found in petroleum. Judicious selection of such hydrophobic subpopulations can enhance hydrocarbon pollution bioremediation.     

Landscape size affects the relative importance of habitat amount,habitat fragmentation,and matrix quality on forest birds

It is important to understand the relative effects of landscape habitat loss, habitat fragmentation, and matrix quality on biodiversity, so that potential management options can be appropriately ranked. However, their effects and relative importance may change with the size of the landscape considered because the multiple (and potentially conflicting) ecological processes that are influenced by landscape structure occur at different spatial scales (e.g. dispersal, predation, foraging). We estimated the relative effects of habitat loss, habitat fragmentation, and matrix quality (measured as the amount of forest, the proportion of forest area contained in large core forests, and the density of roads respectively) on fragmentation‐sensitive forest birds in southern Ontario, Canada using a range of landscape sizes (0.8–310 km²). We used three complementary statistical approaches to estimate relative effects of these correlated landscape factors – 1) multiple regression, 2) information theoretic (AIC) estimates of the most parsimonious model, and 3) multi‐model inference to average effects across all supported models. We controlled for spatial autocorrelation, local habitat, roadside sampling bias, time of day, season, habitat heterogeneity, and the interaction between the effects of habitat amount and fragmentation. We found that relative effects of habitat amount and fragmentation were scale dependent; habitat amount had a consistently positive effect that was consistent over more than two orders of magnitude in landscape area (~1–300 km²). In contrast, the effects of habitat fragmentation depended on the size of the landscape considered. Indeed, for veery Catharus fuscescens, habitat fragmentation had positive effects at one scale and negative effects at another. The effects of matrix quality were generally weak and changed little with scale. For the number of fragmentation sensitive species and the presence of veery, habitat amount was most important in large landscapes and habitat fragmentation in small landscapes but for the presence of ovenbird Seiurus aurocapilla, habitat amount was most important at all scales.     

Do <Emphasis Type="Italic">Lanice conchilega</Emphasis> (sandmason) aggregations classify as reefs? Quantifying habitat modifying effects

The positive effects of the tube dwelling polychaete Lanice conchilega for the associated benthic community emphasizes this bio-engineer’s habitat structuring capacity (Rabaut et al. in Estuar Coastal Shelf Sci, 2007). Therefore, L. conchilega aggregations are often referred to as reefs. The reef building capacity of ecosystem engineers is important for marine management as the recognition as reef builder will increase the protected status the concerned species. To classify as reefs however, bio-engineering activities need to significantly alter several habitat characteristics: elevation, sediment consolidation, spatial extent, patchiness, reef builder density, biodiversity, community structure, longevity and stability [guidelines to apply the EU reef-definition by Hendrick and Foster-Smith (J Mar Biol Assoc UK 86:665–677, 2006)]. This study investigates the physical and temporal characteristics of high density aggregations of L. conchilega. Results show that the elevation and sediment consolidation of the biogenic mounds was significantly higher compared to the surrounding unstructured sediment. Areas with L. conchilega aggregations tend to be extensive and patchiness is high (coverage 5–18%). The discussion of present study evaluates whether L. conchilega aggregations can be considered as reefs (discussing physical, biological and temporal characteristics). Individual aggregations were found to persist for several years if yearly renewal of existing aggregations through juvenile settlement occurred. This renewal is enhanced by local hydrodynamic changes and availability of attaching structures (adult tubes). We conclude that the application of the EU definition for reefs provides evidence that all physical and biological characteristics are present to classify L. conchilega as a reef builder. For temporal characteristics, this study shows several mechanisms exist for reefs to persist for a longer period of time. However, a direct evidence of long-lived individual reefs does not exist. As a range of aggregation development exists, ‘reefiness’ is not equal for all aggregations and a scoring table to quantify L. conchilega reefiness is presented.     

Benthic resting eggs of calanoid copepods in Norwegian enclosures used in mariculture: abundance, species composition and hatching

Abundance, species composition and viability of benthic resting eggs of calanoid copepods were investigated in the sediments of seven Norwegian enclosed pond systems used in mariculture as well as in the sediments of the nearby open sea. The ponds represented different types of morphometry and zooplankton communities and were located from approximately 60 to 70 °N. Differences in environmental conditions in deep water also typical with anoxia and the presence of hydrogen sulphide at most of the localities. The lowest and highest egg densities in the enclosures were 7.5 ± 6.4 × 10⁴ and 5.5 ± 2.5 × 10⁶ m^-2, respectively, higher than in the sediments of the nearby open sea. Highest densities were found at larger or median depths. Altogether, egg densities higher than 10³ m^-2 were found of only four calanoid species; Eurytemora affinis, Acartia teclae, Acartia clausi, Temora longicornis. Hatching success was variable (0–92%), and no significant correlation to the presence of anoxia and hydrogen sulphide was found. This high hatching success was achieved with eggs exposed to hydrogen sulphide for several months. The recruitment potential to the plankton of nauplii was estimated from 4.8 to 1682 nauplii l^-1 for the different localities. The results showed that resting egg production is a common life history characteristic of some neritic calanoid species in Norwegian waters. In addition to copepod eggs, low densities (< 10³ m^-2) of eggs from rotifers and cladocerans were found in most of the localities.