Habitat associations of juvenile fish at Ningaloo Reef, Western Australia: the importance of coral and algae

Habitat specificity plays a pivotal role in forming community patterns in coral reef fishes, yet considerable uncertainty remains as to the extent of this selectivity, particularly among newly settled recruits. Here we quantified habitat specificity of juvenile coral reef fish at three ecological levels; algal meadows vs. coral reefs, live vs. dead coral and among different coral morphologies. In total, 6979 individuals from 11 families and 56 species were censused along Ningaloo Reef, Western Australia. Juvenile fishes exhibited divergence in habitat use and specialization among species and at all study scales. Despite the close proximity of coral reef and algal meadows (10's of metres) 25 species were unique to coral reef habitats, and seven to algal meadows. Of the seven unique to algal meadows, several species are known to occupy coral reef habitat as adults, suggesting possible ontogenetic shifts in habitat use. Selectivity between live and dead coral was found to be species-specific. In particular, juvenile scarids were found predominantly on the skeletons of dead coral whereas many damsel and butterfly fishes were closely associated with live coral habitat. Among the coral dependent species, coral morphology played a key role in juvenile distribution. Corymbose corals supported a disproportionate number of coral species and individuals relative to their availability, whereas less complex shapes (i.e. massive & encrusting) were rarely used by juvenile fish. Habitat specialisation by juvenile species of ecological and fisheries importance, for a variety of habitat types, argues strongly for the careful conservation and management of multiple habitat types within marine parks, and indicates that the current emphasis on planning conservation using representative habitat areas is warranted. Furthermore, the close association of many juvenile fish with corals susceptible to climate change related disturbances suggests that identifying and protecting reefs resilient to this should be a conservation priority.     

Coastal Fish Assemblages Reflect Geological and Oceanographic Gradients Within An Australian Zootone

Distributions of mobile animals have been shown to be heavily influenced by habitat and climate. We address the historical and contemporary context of fish habitats within a major zootone: the Recherche Archipelago, southern western Australia. Baited remote underwater video systems were set in nine habitat types within three regions to determine the species diversity and relative abundance of bony fishes, sharks and rays. Constrained ordinations and multivariate prediction and regression trees were used to examine the effects of gradients in longitude, depth, distance from islands and coast, and epibenthic habitat on fish assemblage composition. A total of 90 species from 43 families were recorded from a wide range of functional groups. Ordination accounted for 19% of the variation in the assemblage composition when constrained by spatial and epibenthic covariates, and identified redundancy in the use of distance from the nearest emergent island as a predictor. A spatial hierarchy of fourteen fish assemblages was identified using multivariate prediction and regression trees, with the primary split between assemblages on macroalgal reefs, and those on bare or sandy habitats supporting seagrass beds. The characterisation of indicator species for assemblages within the hierarchy revealed important faunal break in fish assemblages at 122.30 East at Cape Le Grand and subtle niche partitioning amongst species within the labrids and monacanthids. For example, some species of monacanthids were habitat specialists and predominantly found on seagrass (Acanthaluteres vittiger, Scobinichthys granulatus), reef (Meuschenia galii, Meuschenia hippocrepis) or sand habitats (Nelusetta ayraudi). Predatory fish that consume molluscs, crustaceans and cephalopods were dominant with evidence of habitat generalisation in reef species to cope with local disturbances by wave action. Niche separation within major genera, and a sub-regional faunal break, indicate future zootone mapping should recognise both cross-shelf and longshore environmental gradients.     

Macroalgal Composition Determines the Structure of Benthic Assemblages Colonizing Fragmented Habitats

Understanding the consequences of fragmentation of coastal habitats is an important topic of discussion in marine ecology. Research on the effects of fragmentation has revealed complex and context-dependent biotic responses, which prevent generalizations across different habitats or study organisms. The effects of fragmentation in marine environments have been rarely investigated across heterogeneous habitats, since most studies have focused on a single type of habitat or patch. In this study, we assessed the effects of different levels of fragmentation (i.e. decreasing size of patches without overall habitat loss). We measured these effects using assemblages of macro-invertebrates colonizing representative morphological groups of intertidal macroalgae (e.g. encrusting, turf and canopy-forming algae). For this purpose, we constructed artificial assemblages with different combinations of morphological groups and increasing levels of fragmentation by manipulating the amount of bare rock or the spatial arrangement of different species in mixed assemblages. In general, our results showed that 1) fragmentation did not significantly affect the assemblages of macroinvertebrates; 2) at greater levels of fragmentation, there were greater numbers of species in mixed algal assemblages, suggesting that higher habitat complexity promotes species colonization. Our results suggest that predicting the consequences of fragmentation in heterogeneous habitats is dependent on the type and diversity of morphological groups making up those habitats.     

Intertidal community structure differs significantly between substrates dominated by native eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis> L.) and adjacent to the introduced oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis> (Thunberg) in British Columbia,Canada

Eelgrass beds represent important habitats for marine organisms, but are in decline in many coastal areas around the world. On Cortes Island, British Columbia, Canada, oysters coexist regionally with native eelgrass (Zostera marina L.), but eelgrass is typically absent directly seaward of oyster beds (the “below-oyster cobble zone”). We compared assemblage structure of nekton (fish and swimming macroinvertebrates) and epibenthos (macroinvertebrates and macroalgae) between eelgrass bed and below-oyster habitats. We sampled the intertidal zone on Cortes Island at low tide using two methods: quadrats to enumerate epibenthic macroinvertebrates and macroalgae, and beach seines to enumerate fish and swimming macroinvertebrates. Using multivariate analysis of similarity (ANOSIM), we found that the structure of nektonic and epibenthic assemblages associated with below-oyster cobble zones were significantly different from those in eelgrass-beds. Univariate measures showed that nektonic species richness and abundance were significantly higher in eelgrass beds than in below-oyster cobble habitat, whereas epibenthic species richness and abundance were significantly higher in below-oyster habitat. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: J. Trexler     

Mapping habitat indices across river networks using spatial statistical modelling of River Habitat Survey data

Freshwater ecosystems are declining faster than their terrestrial and marine counterparts because of physical pressures on habitats. European legislation requires member states to achieve ecological targets through the effective management of freshwater habitats. Maps of habitats across river networks would help diagnose environmental problems and plan for the delivery of improvement work. Existing habitat mapping methods are generally time consuming, require experts and are expensive to implement. Surveys based on sampling are cheaper but provide patchy representations of habitat distribution. In this study, we present a method for mapping habitat indices across networks using semi-quantitative data and a geostatistical technique called regression kriging. The method consists of the derivation of habitat indices using multivariate statistical techniques that are regressed on map-based covariates such as altitude, slope and geology. Regression kriging combines the Generalised Least Squares (GLS) regression technique with a spatial analysis of model residuals. Predictions from the GLS model are ‘corrected’ using weighted averages of model residuals following an analysis of spatial correlation. The method was applied to channel substrate data from the River Habitat Survey in Great Britain. A Channel Substrate Index (CSI) was derived using Correspondence Analysis and predicted using regression kriging. The model explained 74% of the main sample variability and 64% in a test sample. The model was applied to the English and Welsh river network and a map of CSI was produced. The proposed approach demonstrates how existing national monitoring data and geostatistical techniques can be used to produce continuous maps of habitat indices at the national scale.     

Habitat conservation prioritization: A floristic approach applied to a Mediterranean wetland network

The importance of plant communities for conservation purposes is recognized in their inclusion in the “Habitat Directive” (92/43 EEC), that relates habitat types to plant community syntaxonomic units. However, habitat definitions in the Habitat Directive lead to several inaccuracies in local habitat characterization. Several wetland plant communities (and their corresponding habitats), rare in the Mediterranean basin, are not included in the Habitat Directive. This study proposes criteria for assessing the conservation importance of habitats. It deals with plant community types at the alliance level, as promising units for setting conservation priorities. The principle criteria considered as drivers for setting alliance conservation values are the distribution and abundance of plant species of conservation interest and their fidelity to a plant community. Multivariate methods were used, and a quantitative floristic index of alliance conservation priority was created. This procedure was applied to an important wetland in central Italy. Results emphasize: (i) high conservation values of some alliances not listed in the Habitat Directive, confirming various gaps in the current conservation law affecting Mediterranean wetlands; (ii) that habitats widely distributed in other biogeographical areas, may greatly underestimate their conservation importance in Mediterranean region; (iii) need to consider regional peculiarities when setting conservation priorities.     

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.     

Predicting the in-between: Present and future habitat suitability of an intertidal euryhaline fish

New World mangrove trees are foundation species, and their range is predicted to expand northward with climate change. Foundation species are commonly prioritized for conservation, with the goal of preserving the entire community that depends on them. However, no studies have explicitly investigated whether mangrove-dependent species' ranges will track the northward expansion of New World mangrove forests. We use the mangrove rivulus fish, Kryptolebias marmoratus, to investigate shifts in habitat suitability in response to various climate change scenarios (Representative Concentration Pathways 2.6, 4.5, 6.0, and 8.5). Niche models for coastal species focus on traditional climatic variables (e.g., precipitation, temperature) even though coastal habitats also are directly influenced by marine variables (e.g., sea surface salinity). We employ a novel data integration method that combines marine and climatic variables, and that accounts for model selection uncertainty using model averaging to provide robust estimates of habitat suitability. Contrary to expectation, suitability of rivulus habitat is predicted to increase in the south and decrease or remain unchanged in the north across all climate change scenarios. Thus, rivulus might experience range contraction, not expansion. Habitat became more suitable with increased salinity of the saltiest month and precipitation of the driest quarter. In laboratory settings, rivulus have higher survival, reproductive success, and growth rates in low salinities. This discrepancy suggests that some combination of the responses of rivulus and its competitors to environmental change will restrict rivulus to habitats that laboratory experiments consider suboptimal. Our models suggest that focusing conservation decisions on foundation species could overestimate habitat availability and resilience of affiliated communities while simultaneously underestimating species declines and extinction risks.     

Habitat type and complexity drive fish assemblages in a tropical seascape

Inshore marine seascapes support a diversity of interconnected habitats and are an important focus for biodiversity conservation. This study examines the importance of habitat attributes to fish assemblages across a mosaic of inshore habitats: coral reefs, rocky reefs, macroalgae beds and sand/rubble beds. Fishes and benthic habitats were surveyed at 34 sites around continental islands of the central Great Barrier Reef using baited remote underwater video stations (BRUVS). Species richness was influenced foremost by habitat type and also by structural complexity within habitat types. The most speciose assemblages occurred in coral and rocky reef habitats with high structural complexity, provided by the presence of coral bommies/overhangs, boulders and rock crevices. Nonetheless, macroalgae and sand/rubble beds also supported unique species, and therefore contributed to the overall richness of fish assemblages in the seascape. Most trophic groups had positive associations with complexity, which was the most important predictor for abundance of piscivorous fishes and mobile planktivores. There was significant differentiation of fish assemblages among habitats, with the notable exception of coral and rocky reefs. Species assemblages overlapped substantially between coral and rocky reefs, which had 60% common species, despite coral cover being lower on rocky reefs. This suggests that, for many species, rocky and coral substrates can provide equivalent habitat structure, emphasizing the importance of complexity in providing habitat refuges, and highlighting the contribution of rocky reefs to habitat provision within tropical seascapes. The results of this study support an emerging recognition of the collective value of habitat mosaics in inshore marine ecosystems.     

Habitat heterogeneity promotes the coexistence of exotic seaweeds

Despite the progressive accumulation of exotic species in natural communities, little effort has been devoted to elucidating the mechanisms underpinning the coexistence of invaders in environmentally and biologically heterogeneous systems. The exotic seaweeds, Asparagopsis taxiformis and Caulerpa racemosa, exhibit a segregated distribution on Mediterranean rocky reefs. A. taxiformis dominates assemblages in topographically complex habitats, but is virtually absent on homogenous platforms. In contrast, C. racemosa achieves extensive cover in both types of habitat. We assessed whether differences in their distribution were generated by biotic interactions (between invaders and/or between invaders and natives) or by environmental constraints. Three models were proposed to explain seaweed distribution patterns: (1) invaders inhibit one another; (2) native assemblages, differing between complex and simple habitats, prevent the establishment/spread of one invader, but not that of the other; and (3) environmental conditions regulate the establishment/persistence of the seaweeds in different habitats. We removed the dominant invader and resident assemblages in each type of habitat. Moreover, A. taxiformis thalli were transplanted into the habitat dominated by C. racemosa to establish whether its failure to colonize the simple habitat was due to the lack of propagules or post-recruitment mortality. C. racemosa spread in the complex habitat was not influenced by the removal of resident assemblages, but it was slightly enhanced by A. taxiformis removal. Neither C. racemosa removal nor that of resident assemblages promoted A. taxiformis colonization and survival in simple habitats. Our results suggest that heterogeneity in environmental conditions can promote invader coexistence by mitigating the effects of negative biotic interactions. Therefore, the accumulation of introduced species in native communities does not necessarily imply established invaders fostering further invasion.     

基于不同视角与方法的北京市密云区生境规划对比

由快速城市化导致的生境破碎化严重影响了生态系统的服务功能。因此,保护与规划城市生境尤为重要。然而目前科学的生境规划设计方法仍有待探索,因为生境的定义具有不同的视角与内涵。基于保护生物学与景观生态学理论,对比了物种视角与景观视角下的2种规划思路,并结合北京市密云区的生境规划,分析对比2种方法的规划结果。在物种方法中,首先选取承担多种生态作用的豹猫为目标物种,运用HSI模型并结合专家赋值法和层次分析法确定每个评价因子的权重,最后通过ArcGIS计算选取高适宜性源地并建立生态网络。景观方法则基于ArcGIS、Guidos、Conefor等软件平台,采用MSPA和景观连通性分析方法,选取重要核心区源地并建立景观生境网络。研究结果表明,2种方法的源地分布差异较大。因此生境规划不能盲目选择一种方法,需有机结合2种方法得到源地与廊道结果。根据地块承载的生境生态功能重要程度确定源地核心保护区,以实现最佳的生境规划和有效的生态系统服务。     

Modelling benthic habitats and biotopes off the coast of Norway to support spatial management

Habitat conservation, and hence conservation of biodiversity hinges on knowledge of the spatial distribution of habitats, not least those that are particularly valuable or vulnerable. In offshore Norway, benthic habitats are systematically surveyed and described by the national programme MAREANO (Marine AREAl database for NOrwegian waters). Benthic habitats and biotopes are defined in terms of the species composition of their epibenthic megafauna. Some habitats are of special conservation interest on account of their intrinsic value and/or vulnerability (e.g., long-lived species, rareness, to comply with international regulations such as OSPAR). In Norway, off Nordland and Troms, the following habitats of special interest can be found: Umbellula encrinus Stands, Radicipes sp. Meadows, Deep Sea Sponge Aggregations, Seapen and Burrowing Megafauna Communities, Hard Bottom Coral Gardens. In this paper, we used underwater video data collected within the MAREANO programme to define and describe benthic habitats and biotopes of special interest, and to map the geographic distribution thereof by means of habitat modelling.We first evaluated the community structure of each habitat in the list using a SIMPROF test. We determined that the class Deep Sea Sponge Aggregations, as defined by OSPAR, had to be split into at least three classes. We then re-defined seven new types of ecological features, including habitats and biotopes that were sufficiently homogeneous. Then we modelled the spatial distributions of these habitats and biotopes using Conditional Inference Forests. Since the purpose of the distribution maps is to support spatial planning we classified the heat maps using density thresholds.The accuracy of models ranged from fair to excellent. Hard Bottom Coral Gardens were the most rare habitat in terms of total area predicted (224 km², 0.3% of the area modelled), closely followed by Radicipes Meadows (391 km², 0.6%). Soft Bottom Demosponges (Geodid sponges and other taxa) represent the largest habitat, with a predicted area of 9288 km² (14%). Distribution maps of classes defined by habitat-forming species (Hard Bottom Coral Gardens) were more reliable than those defined by a host of species, or where no single species was a clear habitat provider (e.g. Seapen and Burrowing Megafauna Communities). We also put forward that a scale of patchiness larger than the scale of observation, and homogeneity of the community both play a role in model performance, and hence in map usefulness. These along with density threshold values based on observed data should all be taken into account in marine classifications and habitat definitions.     

论自然保护与资源开发的策略

物种保护的根本途径是保护其生境,生境的完整性遭到破坏则物种将趋于灭绝［１,２］。不少国家的政府及非政府组织正投入巨资设置保护区试图将至少部分生物多样性资源加以永久保存［３］,但这些目标的达到往往是基于如下假设：即保护区将不受干扰、原封不动的加以保存并与经济活动及周围环境难以达成任何形式的妥协。然而越来越多的证据表明,在全球范围遭受人类干扰的背景下无论是保护区内还是保护区外的生境均将趋于退化,因此现行建立保护区的模式并不能有效阻止生物多样性灾难性的损失［４］。特别对于发展中国家,人口、资源、环境的…     

Human altered ecosystems: suitable habitats as well as ecological traps for dragonflies (Odonata): the matter of scale

Habitat loss and degradation can be considered as major threats to freshwater invertebrates. These often irreversible processes lead to reduction of habitat patch quality and cause local extinctions of dragonflies, notably of habitat specialists. However, the biodiversity of specific secondary habitats is very high. Here, we present findings from a 10-year study that intensively monitored odonate fauna in the Upper Silesian industrial coal region having many secondary habitats characterized by very frequent disturbances due to soil instability. We evaluated qualitative changes in the dragonfly assemblages on 10 patches using a modified dragonfly biotic index. Data analysis was supplemented by a model examining population dynamics of the threatened dragonfly Leucorrhinia pectoralis, using the capture-mark-recapture method, as an effective indicator of habitat quality. We show that dynamics of environmental conditions in secondary habitats are reflected in population dynamics of dragonfly populations and assemblages. As frequency of L. pectoralis population extinctions within the patch is considerable and independent of size and spatial isolation of single habitats, these can be regarded as ecological traps. Nevertheless, the metapopulation dynamics may be a key adaptation of dragonflies to frequent freshwater habitat disturbances. We suggest that local extinctions are effectively balanced with (re-)colonization of newly emerging freshwater habitats. These findings have implications for potential conservation management of specific human-made habitats, because secondary habitats with a great diversity of succession stages arising directly as a consequence of environmental instability may be considered as partial alternatives to natural habitats in cultural landscapes.     

Changes in use of lake habitat by experimentally segregated populations of cutthroat trout and Dolly Varden char

The role of competition in a lacustrine community of two salmonid species, cutthroat trout Oncorhynchus clarki and Dolly Varden char Salvelinus malma , was studied in three coastal British Columbia lakes Habitat use by the species alone (allopatric) and in coexistence with each other (sympatric) was investigated by gill netting at 0-40 m depth contours (surface to bottom) so that several habitats (littoral, epipelagic. pelagic, epibenthic) were sampled From June to October, trout used mainly littoral and epipelagic habitats in sympatry and allopatry Char used all habitats in allopatry. and deep habitats (pelagic, epibenthic) not frequented by trout in sympatry The two species were thus spatially segregated with depth in sympatry Diel (day, night) and seasonal changes (spring, summer, autumn) in habitat use were not pronounced The shift in habitat use by experimentally allopatric char but not trout suggests that the effects of competition between sympatric trout and char for habitat resources are greater on the char     

基于MaxEnt模型的渤海湾沿岸鸻鹬类栖息地适宜性评价

渤海湾沿岸是鸻鹬类迁徙路线的重要栖息地。由于自然和人为原因,栖息地面积减少,质量恶化。因此,开展渤海湾沿岸鸻鹬类栖息地适宜性评价,对湿地生物多样性保护有重要意义。基于鸻鹬类点位信息和环境因子数据,利用MaxEnt模型对渤海湾沿岸2000年和2015年鸻鹬类栖息地适宜性进行评价。结果表明:土地利用/覆被、NDVI、年均气温、坡向是影响鸻鹬类分布的主要因子;鸻鹬类适宜栖息地主要分布在河北唐山南部和天津滨海地区。研究时段内渤海湾沿岸适宜栖息地面积总体有所下降,河北适宜栖息地面积下降,天津和山东增加;栖息地适宜性增加地区主要集中于天津南部、山东东南部,下降地区主要分布在河北丰南、黄骅及天津宁河县。该研究可识别渤海湾沿岸鸻鹬类适宜栖息地的分布范围及变化趋势,对该区域鸻鹬类保护及栖息地管理具有重要参考意义。     

元江-李仙江流域亚洲象生境适宜性评价——基于荟萃分析和遥感大数据分析

生境适宜性评价是物种保护和生境管理与规划的基础。近几十年来，云南境内野生亚洲象数量剧增，外扩迁移事件频发，而新迁入区域生境适宜状况因物种出现点数据缺乏而难以评价，掣肘迁移亚洲象保护与风险防范应急。以亚洲象新近迁入的元江-李仙江流域为案例区，采用荟萃分析统计亚洲象生境评价因子，结合相关性分析和方差膨胀因子独立性检验，筛选出生境评价因子；基于开源遥感数据产品量化生境因子，综合主成分分析和层次分析计算生境评价因子权重，采用生境适宜性指数(Habitat Suitability Index, HSI)模型评价元江-李仙江流域亚洲象生境适宜性，并分析其景观格局。结果表明：(1)元江-李仙江流域亚洲象生境适宜性空间格局主要表现为由下游至上游呈递减趋势，最适生境主要分布于流域下游段，而流域上游段适宜生境少；(2)元江流域生境适宜性低于李仙江流域，且其生境斑块连接度更低、破碎化更严重；(3)2021年“北移象群”北迁沿程生境适宜性由西南向东北呈下降趋势。基于亚洲象生境适宜性评价结果，科学引导野生亚洲象迁入适宜生境区，以规避人象冲突，保障外迁亚洲象群及其活动区居民生命财产安全，服务于区域生物多样性保护与...     

Habitat Use by Fishes in Coral Reefs,Seagrass Beds and Mangrove Habitats in the Philippines

Understanding the interconnectivity of organisms among different habitats is a key requirement for generating effective management plans in coastal ecosystems, particularly when determining component habitat structures in marine protected areas. To elucidate the patterns of habitat use by fishes among coral, seagrass, and mangrove habitats, and between natural and transplanted mangroves, visual censuses were conducted semiannually at two sites in the Philippines during September and March 2010–2012. In total, 265 species and 15,930 individuals were recorded. Species richness and abundance of fishes were significantly higher in coral reefs (234 species, 12,306 individuals) than in seagrass (38 species, 1,198 individuals) and mangrove (47 species, 2,426 individuals) habitats. Similarity tests revealed a highly significant difference among the three habitats. Fishes exhibited two different strategies for habitat use, inhabiting either a single (85.6% of recorded species) or several habitats (14.4%). Some fish that utilized multiple habitats, such as Lutjanus monostigma and Parupeneus barberinus, showed possible ontogenetic habitat shifts from mangroves and/or seagrass habitats to coral reefs. Moreover, over 20% of commercial fish species used multiple habitats, highlighting the importance of including different habitat types within marine protected areas to achieve efficient and effective resource management. Neither species richness nor abundance of fishes significantly differed between natural and transplanted mangroves. In addition, 14 fish species were recorded in a 20-year-old transplanted mangrove area, and over 90% of these species used multiple habitats, further demonstrating the key role of transplanted mangroves as a reef fish habitat in this region.     

Recent change in spatial distribution of the European flat oyster (Ostrea edulis) inferred from field data and empirical models of living oysters and empty shells

Marine coastal areas are increasingly affected by human activities resulting in changes in species and habitat distributions. Understanding these patterns and its causes and consequences is important for conservation and restoration of such changing habitats. One habitat that has been heavily affected by human use are the North Sea oyster beds which once were abundant but have lost large parts of its coastal distribution due to overexploitation. Based on data of living and dead assemblages of Ostrea edulis collected using video transects, we used an ensemble modeling technique to model and predict current and recent distribution of O. edulis along the Swedish west coast where its distribution is, in relative terms, still rather unaffected. We could detect a recent change in the distribution of O. edulis along the coast which to a large extent could be attributed to a change in depth distribution, suggesting that the population of O. edulis have a slightly shallower distribution today than in the past. Although a potential mismatch between living and dead assemblages, caused by a complex combination of biological and environmental conditions, needs to be considered in the interpretations drawn, it may be a way around the lack of suitable background data in management decisions. This provides important information for management and conservation of the native oyster beds. Furthermore, this study illustrates a method for identifying recent changes in species distribution using dead assemblages of bivalves.     

Patterns of distribution and movement of fishes, <Emphasis Type="Italic">Ophthalmolepis lineolatus</Emphasis> and <Emphasis Type="Italic">Hypoplectrodes maccullochi</Emphasis>, on temperate rocky reefs of south eastern Australia

Current ecological models predict that reef fish assemblages will be strongly influenced by habitat type. Here we test hypotheses about habitat types and abundance patterns of temperate reef fishes from broad spatial scales (100 s of km) to small spatial scales of metres to tens of metres. Habitat preferences are also described over long periods of time (22 years) for two abundant taxa. Patterns of distribution and abundance varied over ～ eight degrees of latitude (29.9–37.5°S) along the coast of New South Wales, Australia. Ophthalmolepis lineolatus (Labridae) preferred kelp and Barrens habitats and juveniles were most abundant in habitats rich in algae. This species also increased in abundance from North to South. In contrast, Hypoplectrodes maccullochi (Serranidae) were usually only found in the Barrens habitat and great variation was found among locations. Both taxa were most abundant on urchin grazed deep reefs (over 10 m deep). Habitat preferences of O. lineolatus and H. maccullochi appeared resistant to major environmental perturbations that included large El Niño events in 1991, 1998 and 2002. Home ranges of O. lineolatus varied from 52 m² to 1,660 m² and often overlapped; fish of all sizes were most abundant in algal dominated habitat. Limited movements and small home ranges (2.1–11.6 m²) combined with a strong affiliation for shelter indicated that most H. maccullochi are strongly site-attached. Habitat type is important to these taxonomically different fishes, but to varying degrees where H. maccullochi was more of a habitat specialist than O. lineolatus and would be more vulnerable to perturbations that alter Barrens. Changes in reef habitats will have a great influence on fish assemblages and this should also be considered in coastal planning (e.g. for Marine Protected Areas, MPAs) and the assessments of resistance and resilience of fishes to climate change.