Marine dock pilings foster diverse,native cryptobenthic fish assemblages across bioregions

Anthropogenic habitats are increasingly prevalent in coastal marine environments. Previous research on sessile epifauna suggests that artificial habitats act as a refuge for nonindigenous species, which results in highly homogenous communities across locations. However, vertebrate assemblages that live in association with artificial habitats are poorly understood. Here, we quantify the biodiversity of small, cryptic (henceforth “cryptobenthic”) fishes from marine dock pilings across six locations over 35° of latitude from Maine to Panama. We also compare assemblages from dock pilings to natural habitats in the two southernmost locations (Panama and Belize). Our results suggest that the biodiversity patterns of cryptobenthic fishes from dock pilings follow a Latitudinal Diversity Gradient (LDG), with average local and regional diversity declining sharply with increasing latitude. Furthermore, a strong correlation between community composition and spatial distance suggests distinct regional assemblages of cryptobenthic fishes. Cryptobenthic fish assemblages from dock pilings in Belize and Panama were less diverse and had lower densities than nearby reef habitats. However, dock pilings harbored almost exclusively native species, including two species of conservation concern absent from nearby natural habitats. Our results suggest that, in contrast to sessile epifaunal assemblages on artificial substrates, artificial marine habitats can harbor diverse, regionally characteristic assemblages of vertebrates that follow macroecological patterns that are well documented for natural habitats. We therefore posit that, although dock pilings cannot function as a replacement for natural habitats, dock pilings may provide cost‐effective means to preserve native vertebrate biodiversity, and provide a habitat that can be relatively easily monitored to track the status and trends of fish biodiversity in highly urbanized coastal marine environments.     

Fish Assemblages on Estuarine Artificial Reefs: Natural Rocky-Reef Mimics or Discrete Assemblages?

If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef''s isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring habitat comprised of species that reside on a range of adjacent natural habitats.     

Natural cultch type influences habitat preference and predation,but not survival,in reef‐associated species

A shared origin with fresh and dredged cultch and availability via mining have made fossil cultch a commonly used reef restoration substrate. However, important differences in shape and size between whole‐shell cultch and fossil cultch may impact the complexity of reefs constructed from these materials. To determine if these differences may impact the development of restored reefs, we quantified the interstitial space each cultch type provides and constructed reef mesocosms to measure (1) the immediate effects of exposure to each cultch type on mortality of blue crab (Callinectes sapidus) and pink shrimp (Farfantepenaeus duorarum); (2) the tendency of crab, shrimp, and Florida crown conch (Melongena corona) to be found on habitats composed of each substrate type and their position within each in split‐substrate mesocosms; and (3) the influence of cultch type on predation of Eastern oysters (Crassostrea virginica) by crabs and conch. Aggregation of fossil cultch contains more shells and provides less interstitial space than an equivalent volume of whole‐shell cultch. Although immediate mortality following deployment was low and did not differ among cultch types, we found that all species were more likely to be found on fresh cultch over fossil cultch in choice experiments and used each habitat type differently. Cultch type also impacted the size of oysters consumed by crabs in short‐term feeding trials. The structure and traits of habitats created by various materials should be added to the growing list of issues considered when natural communities are to be restored in oyster reefs and other environments.     

Limited habitat and conservation value of a young artificial reef

Loss and degradation of natural habitats and their biodiversity may, arguably, be mitigated or compensated through the creation of human-engineered habitats: the underlying conservation tenet is that these artificial habitats compensate for diminished diversity caused by human impacts at local or regional scales. This approach is widely used in the sea by purposefully scuttling ships to create artificial reefs, but its performance as a conservation tool is seldom critically examined in these situations. Here we test if the diversity of sessile invertebrate assemblages on a large, but young (3 years), artificial reef, created by sinking a 133 m long battle ship off Eastern Australia, can mimic that of nearby natural reefs. We use this system as a model to test whether this artificial reef can form compensatory habitat of comparable quality and levels of biodiversity. Our assessment is based on the abundance, species richness, and species composition of sessile invertebrate assemblages, including corals. Despite some signs that temporal trajectories of ecological metrics, such as cover, began to approach natural conditions after 3 years, the ecological structure of sessile invertebrate assemblages on this young wreck remained fundamentally different from those on nearby natural reefs. In particular, large, long-lived corals were abundant on natural rocky reefs, but were rare and covered little area on the young wreck. These data demonstrate that when trajectories to community convergence with natural habitats are prolonged, as may be the case here, any compensatory effects of artificial habitats will have a considerable time lag. Such lags have implications for appraising the conservation value of wrecks and artificial reefs, and they emphasize the need to explicitly acknowledge temporal dynamics when using artificial habitats as complementary conservation tools to augment larger conservation efforts on natural systems.     

Depth-associated patterns in the development of benthic assemblages on artificial substrata deployed on shallow, subtropical reefs

Changes in the structure of many benthic habitats occur across a number of physical gradients and result in corresponding changes in the structure of associated epifaunal assemblages; however, investigations of faunal assemblages are often confounded by variation in the morphology of habitats. In this experiment, identical nests of nylon pan scourers were employed to examine changes in the structure of epifaunal assemblages across a depth gradient at two island sites within the Solitary Islands Marine Park (SIMP), NSW, Australia. Artificial substratum units (ASUs) were anchored to rocky reef at 8, 16 and 24 m for a period of five months over summer and winter. Data were subjected to univariate and multivariate statistical analyses to determine the similarity of assemblages across Depths, Islands and Times. A number of species displayed a distinct fidelity with depth across both islands and times. Although significant interactions between factors were apparent for most variables, very few significant differences across the main effects were identified for univariate analyses of summary community variables (S, N, H′), major taxonomic groups (bivalves, amphipods, polychaetes) or individual species analysed. In contrast, multivariate analyses revealed significant differences in assemblage structure for all comparisons of depth during each sampling period. Although the experiment was conducted both over summer and again over winter, depth-associated patterns were maintained at each island during each sampling period. The results highlight the importance of depth as a structuring factor for epifaunal assemblages of subtropical rocky reefs.     

The Substantial First Impact of Bottom Fishing on Rare Biodiversity Hotspots: A Dilemma for Evidence-Based Conservation

This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site.The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track.The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a ‘priority habitat’ the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive) as well as indicators of ‘Good Environmental Status’ under the European Union Marine Strategy Framework Directive.Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.     

Epifaunal colonization of the Loch Linnhe artificial reef: influence of substratum on epifaunal assemblage structure

A one-year study was carried out off the west coast of Scotland to compare the epifaunal colonization of concrete material used in the construction of the Loch Linnhe artificial reef with that on four other types of artificial substrata (preservative treated wood, rubber, steel and PVC). Settlement panels made from each of the materials were submerged in a vertical orientation during four seasonal exposure periods. There were clear seasonal trends across the four exposure periods with higher epifaunal biodiversity on all types of panel in the spring and summer exposure periods. Epifaunal assemblage structure was significantly different between the five types of material after each three-month exposure period. Concrete, preservative treated wood and PVC tended to have the highest species diversities. A successional study was also carried out. Over a 12-month exposure period epifaunal biodiversity increased on all five materials. After 12 months of exposure, the epifaunal assemblage structure was still significantly different between materials but had become more similar indicating a successional change towards a stable assemblage on all panels. The results indicate that material type and season have a significant effect on epifaunal assemblage structure after short (three-month) periods of submersion but that these effects are reduced with increasing length of exposure. The study concludes that the choice of construction material for an artificial reef will have little effect on the long-term epifaunal community structure, as long as the material is physically stable, non-toxic and offers a high degree of habitat complexity.     

Epifaunal colonization of the Loch Linnhe artificial reef: Influence of substratum on epifaunal assemblage structure

A one-year study was carried out off the west coast of Scotland to compare the epifaunal colonization of concrete material used in the construction of the Loch Linnhe artificial reef with that on four other types of artificial substrata (preservative treated wood, rubber, steel and PVC). Settlement panels made from each of the materials were submerged in a vertical orientation during four seasonal exposure periods. There were clear seasonal trends across the four exposure periods with higher epifaunal biodiversity on all types of panel in the spring and summer exposure periods. Epifaunal assemblage structure was significantly different between the five types of material after each three-month exposure period. Concrete, preservative treated wood and PVC tended to have the highest species diversities. A successional study was also carried out. Over a 12-month exposure period epifaunal biodiversity increased on all five materials. After 12 months of exposure, the epifaunal assemblage structure was still significantly different between materials but had become more similar indicating a successional change towards a stable assemblage on all panels. The results indicate that material type and season have a significant effect on epifaunal assemblage structure after short (three-month) periods of submersion but that these effects are reduced with increasing length of exposure. The study concludes that the choice of construction material for an artificial reef will have little effect on the long-term epifaunal community structure, as long as the material is physically stable, non-toxic and offers a high degree of habitat complexity.     

The role of settlement in structuring a hard-substratum community in the deep sea

Larval settlement can play an important role in the structure of benthic communities in shallow-water habitats. Experimental studies of settlement and colonization in the deep sea, however, are few, and have concentrated exclusively on sedimentary habitats. Results are presented here from an in situ study designed to determine whether larval settlement patterns on a common, deep-sea hard substratum (manganese nodules) determine the subsequent structure of the epifaunal community. In a 7-wk deployment at a depth of 1240 m, settlement onto manganese nodules resting on the sediment in a relatively “low-flow” environment was significantly greater than onto nodules suspended in a “higher-flow” regime. After 2 yr, this difference in total number of individuals was no longer significant, but a new pattern in community composition emerged, which correlated to the presumed supply of paniculate food. Suspension-feeders dominated the elevated nodules (correlating to higher horizontal participate fluxes) and deposit-feeders dominated the nodules sitting on the sediment (correlating to higher particulate deposition). The faunal settlement patterns observed after 7 wk, therefore, appear to be altered by adult feeding requirements of the component species.     

Influence of fish grazing and sedimentation on the early post-settlement survival of the tabular coral Acropora cytherea

Processes operating in the early life stages of corals are critical in ultimately establishing patterns of adult abundance. Mortality, in particular, is assumed to be very high during the first few months to years post-settlement, but the sources of this mortality are largely unknown. This study quantified early post-settlement survival for Acropora cytherea, spawned and reared in captivity and settled onto terracotta tiles. Replicate tiles were then deployed in the field at Lizard Island, in northern section of the Great Barrier Reef to examine the effects of grazing and sedimentation on survival of corals in two different habitats, the exposed reef crest and sheltered back reef. Overall, survivorship was broadly comparable between habitats, ranging from 37.7 to 64.5 % per month on the exposed reef crest and 53.1–64.3 % on the sheltered back reef. On the reef crest, the exclusion of herbivores increased survivorship by 22.4 %, from 42.1 to 64.5 % per month. Moreover, survivorship within the reef crest was negatively correlated with the density of parrotfish feeding scars on tiles after 4 weeks. In contrast, the exclusion of herbivores had no detectable effect on survivorship within the back reef, and no feeding scars were observed on tiles in this habitat. Difference in grazing-induced mortality between habitats is most likely related to differences in herbivore size and abundance, with parrotfish biomass being 5.5-fold greater on the reef crest than the back reef. Surprisingly, tile orientation had no effect on survivorship of A. cytherea in either habitat, despite a marked difference in the sediment cover on vertical (0 %) versus horizontal tiles (30 %) in the back reef. This is in marked contrast to previous studies that have reported sedimentation is a major cause of early post-settlement mortality in corals. Clearly, processes that cause mortality of newly settled corals, such as grazing and sedimentation, vary spatially.     

Application of Acoustic Telemetry to Assess Residency and Movements of Rockfish and Lingcod at Created and Natural Habitats in Prince William Sound

Loss and/or degradation of nearshore habitats have led to increased efforts to restore or enhance many of these habitats, particularly those that are deemed essential for marine fishes. Copper rockfish (Sebastes caurinus) and lingcod (Ophiodon enlongatus) are dominant members of the typical reef fish community that inhabit rocky and high-relief substrates along the Pacific Northwest. We used acoustic telemetry to document their residency and movements in the nearshore waters of Prince William Sound, Alaska in order to assess use of created reef habitat in an individual-based manner. A total of 57 fish were surgically implanted with acoustic transmitters. Forty-five fish were captured and monitored in three habitats: artificial reef, low-relief natural reef, and patchy high-relief natural reef. Within each habitat, both rockfish and lingcod exhibited long periods of residency with limited movements. Twelve rockfish were captured at the natural reefs and displaced a distance of 4.0 km to the artificial reef. Five of the 12 rockfish returned within 10 d of their release to their initial capture site. Another five of the 12 displaced fish established residency at the artificial reef through the duration of our study. Our results suggest the potential for artificial reefs to provide rockfish habitat in the event of disturbances to natural habitat.     

Succession of crustose coralline red algae (Rhodophyta) on coralgal reefs exposed to physical disturbance in the southwest Atlantic

Biological and physical disturbances create the conditions for species succession in any biological ecosystem. In particular, coral reefs are susceptible to this process because of the complexity of their ecological relationships. In the southwest Atlantic, nearshore reefs are mostly coated by a thin layer of coralline crusts rather than stony corals. However, little is known about the succession of crustose coralline algae. We studied this process by means of a series of experimental and control discs exposed to physical disturbance. Our results showed that the dominant species in natural conditions, Pneophyllum conicum, had early recruits and later became dominant on the discs, replicating the community structure of the actual reef. This species had mature reproductive structures and available spores from the beginning of the colonization experiments. Thicker crusts of Porolithon pachydermum and Peyssonnelia sp. were found on the discs after 112 days, and significantly increased their cover over the succeeding months; and after 1 year, P. conicum was less abundant. Physical disturbance increased crust recruitment and the low-light environment created by sediments. The data demonstrated coexistence among crustose coralline species and a tolerance to physical disturbance, which seemed to favor the thinner crusts of P. conicum over thick-crust species during succession. The succession pattern observed in this subtropical Brazilian coral reef differs from that described for shallow tropical reef communities.     

Interactions between herbivorous fish guilds and their influence on algal succession on a coastal coral reef

Herbivory is an important mechanism affecting algal succession, particularly on coral reefs where the relationship between algae and corals is largely controlled by herbivores. However, different functional groups of herbivores may have contrasting effects on succession, which may explain different trajectories of coral reef recovery after disturbance. Here, the effects of different herbivore groups (roving herbivores = foragers and territorial damselfish = farmers) were isolated by a multi-factorial experiment carried out on a coastal coral reef with high macroalgal cover, high farmer densities and relatively low forager abundance. The effects of foragers and farmers were distinguished by monitoring algal succession on settlement tiles placed inside and outside exclusion cages, with orthogonal treatments established inside and outside damselfish territories (with appropriate cage controls). Within 12 months, algal assemblages on ungrazed tiles inside exclusion cages proceeded rapidly from fine filamentous turfs, to corticated algae, to tough erect (e.g. Amphiroa spp.) and foliose (e.g. Peyssonnellidae) calcified algae. Farmers had a dramatic impact on succession, essentially arresting the development of the algal community at a point where it was dominated by palatable filamentous algae of the genus Polysiphonia. Fleshy macroalgae such as Sargassum spp. were excluded from farmer territories. In contrast, foragers did not suppress fleshy macroalgae, but rather, appeared to decelerate succession and promote a relatively diverse assemblage. In contrast to forager-dominated reefs, farmer territories did not appear to function solely as forager exclusion areas or promote algal diversity as a result of intermediate grazing pressure. The relatively strong effects of farmers observed here may represent a future scenario for coral reefs that are increasingly subject to overfishing of large grazing fishes.     

Small invertebrate consumers produce consistent size spectra across reef habitats and climatic zones

Changes in invertebrate body size-distributions that follow loss of habitat-forming species can potentially affect a range of ecological processes, including predation and competition. In the marine environment, small crustaceans and other mobile invertebrates (‘epifauna') represent a basal component in reef food webs, with a pivotal secondary production role that is strongly influenced by their body size-distribution. Ongoing degradation of reef habitats that affect invertebrate size-distributions, particularly transformation of coral and kelp habitat to algal turf, may thus fundamentally affect secondary production. Here we explored variation in size spectra of shallow epifaunal assemblages (i.e. the slope and intercept of the linear relationship between log abundance and body size at the assemblage level) across 21 reef microhabitats distributed along an extensive eastern Australian climatic gradient from the tropical northern Great Barrier Reef to cool temperate Tasmania. When aggregated across microhabitats at the site scale, invertebrate body size spectra (0.125–8 mm range) were consistently log-linear (R² ranging 0.87–0.98). Size spectra differed between, but not within, major groups of microhabitats, and exhibited little variability between tropical and temperate biomes. Nevertheless, size spectra showed significant tropical/temperate differences in slopes for epifauna sampled on macroalgal habitats, and in elevation for soft coral and sponge habitats. Our results reveal epifaunal size spectra to be a highly predictable macro-ecological feature. Given that variation in epifaunal size spectra among groups of microhabitats was greater than variation between tropical and temperate biomes, we postulate that ocean warming will not greatly alter epifaunal size spectra directly. However, transformation of tropical coral and temperate macroalgal habitats to algal turfs due to warming will alter reef food web dynamics through redistribution of the size of prey available to fishes.     

三横山鱼礁生境鱼类和大型无脊椎动物群落特征

为了解三横山人工鱼礁建设的生态效果,2009年1-8月对鱼礁、泥地、岩礁3种生境中的鱼类和大型无脊椎动物组成及环境状况进行了调查,采用丰富度、多样性和均匀度指数及聚类分析等多元统计分析方法对各生境的相关生物群落进行了多方面的比较研究。结果表明:鱼礁区除保留原有泥地生境中的优势种外,还增加了褐菖鲉等岩礁优势种类。鱼礁生境的种类丰富度显著高于泥地和和岩礁生境(P0.05),多样性也明显高于泥地生境(P0.05),但和岩礁生境间并无显著差异(P0.05)。鱼礁和岩礁生境相关群落基本处在同一功能块,且显著区别于泥地群落,但三者之间的种类组成相似性均未达到中等相似水平,仍分属3种不同的群落。温度对鱼礁生境生物群落的相关性最高(0.472),而泥地为叶绿素a(0.459),岩礁为温盐组合因子(0.684),不同生境的生物群落对相同环境因子的响应机制并不同。由此可见,人工鱼礁生境综合了自然和人工环境的特点,其特有的群聚模式对自然群落结构有着互补和强化作用,对保护岩礁资源和岛礁生物多样性起着积极而特殊的作用。     

Artificial algae as habitats for mobile epifauna: factors affecting colonization in a Japanese Sargassum bed

The utility of artificial habitats as tools in benthic studies was assessed by comparing the faunas associated with natural and artificial plants in a Japanese Sargassum bed. The 35 most common epifaunal species collected were all found to associate with both artificial and natural habitats, however, the abundances of species varied considerably between habitats. Colonization of artificial habitats was most rapid between 8 and 24 days after being placed in the field. This increased rate of colonization at intermediate time periods possibly reflected increasing attractiveness of habitats as a periphytic coating developed after the first week. Artificial habitats preconditioned in a sunlit environment to possess a layer of epiphytic algae attracted much higher numbers of epifaunal animals than habitats placed in a darkened but otherwise similar preconditioning environment. Epifaunal species appear to be attracted to artificial substrata, and presumably also natural habitats, largely because of associated diatoms and epiphytic plants.     

Sponge-Microbe Associations Survive High Nutrients and Temperatures

Coral reefs are under considerable pressure from global stressors such as elevated sea surface temperature and ocean acidification, as well as local factors including eutrophication and poor water quality. Marine sponges are diverse, abundant and ecologically important components of coral reefs in both coastal and offshore environments. Due to their exceptionally high filtration rates, sponges also form a crucial coupling point between benthic and pelagic habitats. Sponges harbor extensive microbial communities, with many microbial phylotypes found exclusively in sponges and thought to contribute to the health and survival of their hosts. Manipulative experiments were undertaken to ascertain the impact of elevated nutrients and seawater temperature on health and microbial community dynamics in the Great Barrier Reef sponge Rhopaloeides odorabile. R. odorabile exposed to elevated nutrient levels including 10 µmol/L total nitrogen at 31°C appeared visually similar to those maintained under ambient seawater conditions after 7 days. The symbiotic microbial community, analyzed by 16S rRNA gene pyrotag sequencing, was highly conserved for the duration of the experiment at both phylum and operational taxonomic unit (OTU) (97% sequence similarity) levels with 19 bacterial phyla and 1743 OTUs identified across all samples. Additionally, elevated nutrients and temperatures did not alter the archaeal associations in R. odorabile, with sequencing of 16S rRNA gene libraries revealing similar Thaumarchaeota diversity and denaturing gradient gel electrophoresis (DGGE) revealing consistent amoA gene patterns, across all experimental treatments. A conserved eukaryotic community was also identified across all nutrient and temperature treatments by DGGE. The highly stable microbial associations indicate that R. odorabile symbionts are capable of withstanding short-term exposure to elevated nutrient concentrations and sub-lethal temperatures.     

Spatial scales of bacterial diversity in cold-water coral reef ecosystems

Background

Cold-water coral reef ecosystems are recognized as biodiversity hotspots in the deep sea, but insights into their associated bacterial communities are still limited. Deciphering principle patterns of bacterial community variation over multiple spatial scales may however prove critical for a better understanding of factors contributing to cold-water coral reef stability and functioning.

Methodology/Principal Findings

Bacterial community structure, as determined by Automated Ribosomal Intergenic Spacer Analysis (ARISA), was investigated with respect to (i) microbial habitat type and (ii) coral species and color, as well as the three spatial components (iii) geomorphologic reef zoning, (iv) reef boundary, and (v) reef location. Communities revealed fundamental differences between coral-generated (branch surface, mucus) and ambient microbial habitats (seawater, sediments). This habitat specificity appeared pivotal for determining bacterial community shifts over all other study levels investigated. Coral-derived surfaces showed species-specific patterns, differing significantly between Lophelia pertusa and Madrepora oculata, but not between L. pertusa color types. Within the reef center, no community distinction corresponded to geomorphologic reef zoning for both coral-generated and ambient microbial habitats. Beyond the reef center, however, bacterial communities varied considerably from local to regional scales, with marked shifts toward the reef periphery as well as between different in- and offshore reef sites, suggesting significant biogeographic imprinting but weak microbe-host specificity.

Conclusions/Significance

This study presents the first multi-scale survey of bacterial diversity in cold-water coral reefs, spanning a total of five observational levels including three spatial scales. It demonstrates that bacterial communities in cold-water coral reefs are structured by multiple factors acting at different spatial scales, which has fundamental implications for the monitoring of microbial diversity and function in those ecosystems.     

象山港典型生境沉积物反硝化细菌群落丰度与结构多样性

通过高通量测序和qPCR技术对象山港4种典型生境(牡蛎养殖区OA、海带养殖区SA、自然岛礁区NR、人工鱼礁区AR)和对照区CK的沉积物反硝化细菌丰度和群落结构进行了测定分析,并探讨了反硝化细菌群落与环境因子之间的相关关系.结果表明:沉积物nirK型反硝化细菌丰度在5种生境间没有显著性差异,而沉积物nirS型反硝化细菌丰...     

Effects of grazing by Diadema antillarum Philippi (Echinodermata: Echinoidea) on algal diversity and community structure

In Discovery Bay, Jamaica W.I., densities of Diadema antillarum Philippi were experimentally manipulated over a range of 0–64 individuals · m^?2 with the aid of enclosures in shallow water. The effects of grazing by this echinoid on the algal community structure of a coral reef were compared under conditions of primary and post-primary succession.Algal biomass decreased as Diadema density was increased, particularly under primary succession conditions. A similar response was noted under post-primary conditions, but here biomass was also dependent on species composition and abundance of algae prior to experimental alterations of Diadema density. Peyssonnelia sp. was found to be particularly resistant to echinoid grazing, surviving even the most intense grazing. Within 11 months, algal diversity decreased significantly in an exponential fashion as Diadema density increased. This occurred under conditions of both primary and post-primary succession. Diversity, irrespective of index, was not maximized at intermediate grazing pressures. No single species of alga dominated the benthic community at even the lowest Diadema densities.Species composition of algae in the benthic community prior to changes in grazing pressure and lack of successful recruitment of a potential dominant were found to have a major influence on the response of the algal community to the treatments. Each of these factors can influence both the relationship between algal diversity and grazing pressure and the rate at which the community approaches an initial plateau of diversity in its earliest stages of succession.