Spatial conservation planning under climate change: Using species distribution modeling to assess priority for adaptive management of Fagus crenata in Japan

Protected areas are the basis of modern conservation systems, but current climate change causes gaps between protected areas and the species distribution ranges. To mitigate the impact of climate change on species distribution ranges, revision of protected areas are necessary. Alternatively, active management such as excluding competitive species or transplanting target species would be effective. In this study, we assessed optimal actions (revision of protected areas or active management) in each geographical region to establish an effective spatial conservation plan in Japan. Gaps between the protected areas and future potential habitats were assessed using species distribution models and 20 future climate simulations. Fagus crenata, an endemic and dominant species in Japan, was used as a target species. Potential habitats within the protected areas were predicted to decrease from 22,122 km² at present to 12,309 km² under future climate conditions. Sustainable potential habitats (consistent potential habitats both at present and in future) without the protected areas extended to 13,208 km², and were mainly found in northeast Japan. These results suggest that, in northeast Japan, revisions to protected areas would be effective in preserving sustainable potential habitats under future climate change. However, the potential habitats of southwestern Japan, in which populations were genetically different from northeastern populations, were predicted to virtually disappear both within and outside of protected areas. Active management is thus necessary in southwestern Japan to ensure intraspecific genetic diversity under future climate change.     

The ecology of Potamogeton species in central North America

The distribution of 17 Potamogeton species was examined at 430 sites in central North America with respect to water body type, bottom substrate and 8 water chemistry parameters (pH, total dissolved solids, total alkalinity, chloride, sulphate, phosphorus, combined nitrate and nitrite, and dissolved organic matter). All except 2 of the species showed statistically significant distributions with respect to some of the environmental parameters examined. Each species occupied a different combination of chemical parameter ranges. The species formed a distribution spectrum with respect to water chemistry, with P. epihydrus and P. obtusifolius frequenting low inorganic concentrations at one end of the scale, and P. filiformis, P. pectinatus and P. vaginatus at the other end, these species characterized by high mean inorganic values and occurring most often in saline or alkaline habitats. While 41 significant positive interspecific associations were found within the genus in lentic waters, only 4 were apparent in lotic habitats. Potamogeton species richness (PR) was related to water body and bottom type, with lakes and sand bottoms showing the highest mean PR values. Stepwise multiple regression analysis showed that, in the area as a whole, the water chemistry parameters examined accounted for <25% of the observed variability in PR. The relative importance of individual chemical parameters in relation to PR varied in different water body types.     

Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin,U.S.A.

We sampled zooplankton communities from 54 small water bodies distributed throughout Wisconsin to evaluate whether a snap-shot of zooplankton community structure during early spring could be used for the purpose of differentiating lakes from wetlands. We collected a single set of zooplankton and water chemistry data during a one-month time window (synchronized from south to north across the state) from an open water site in each basin as a means to minimize and standardize sampling effort and to minimize cascading effects arising from predator–prey interactions with resident and immigrant aquatic insect communities. We identified 53 taxa of zooplankton from 54 sites sampled across Wisconsin. There was an average of 6.83 taxa per site. The zooplankton species were distributed with a great deal of independence. We did not detect significant correlations between number of taxa and geographic region or waterbody size. There was a significant inverse correlation between number of taxa and the concentration of calcium ion, alkalinity and conductivity. One pair of taxa, Lynceus brachyurus and Chaoborus americanus, showed a significant difference in average duration of sites of their respective occurrence. All other pairs of taxa had no significant difference in average latitude, waterbody surface area, total phosphorus, total Kjeldahl nitrogen, alkalinity, conductivity, calcium ion, sulfate, nitrate, silicate or chloride. Taxa were distributed at random among the sites – there were no statistically significant pairs of taxa occurring together or avoiding each other. Multivariate analysis of zooplankton associations showed no evidence of distinct associations that could be used to distinguish lakes from wetlands. Zooplankton community structure appears to be a poor tool for distinguishing between lakes and wetlands, especially at the relatively large scale of Wisconsin (dimension of about 500 km). The data suggest that a small body of water in Wisconsin could be classified as a wetland if it persists in the spring and summer for only about 4 months, and if it is inhabited by Lynceus brachyurus, Eubranchipus bundyi, and if Chaoborus americanus and Chydorus brevilabris are absent.     

Vegetation-Environment Relationships in Peatlands Dominated by Sphagnum fallax in Western Poland

We investigated species composition and relative abundance of Sphagnum fallax dominated peatlands in relation to measured environmental variables on the basis of 26 sites in the Wielkopolska region. Most studied plots were characterized by soft waters, poor in Ca²⁺ but rich in nutrients, especially N-NH₄ ⁺ and P-PO₄ ^3-, with high electrolytic conductivity and high DOC (dissolved organic carbon) concentration. Six of the 19 measured variables of surface water chemistry (DOC, pH, SO₄ ^2-, P-PO₄ ^3-, Na⁺ and Ca²⁺) significantly explained 23% of the variation in floristic composition. In 65 vegetation plots, 107 species were observed. Cluster analysis revealed four types of vegetation in the studied mires. Sphagnum fallax was the most abundant species and formed plant communities in a wide range of habitats: in floating mats, with the plants usually adjoining the mineral basin edge (e.g. E. vaginatum, Andromeda polifolia and Ledum palustre) as well as it occupied central parts of Sphagnum lawn (e.g. Eriophorum angustifolium) and rich fen habitats (e.g. Carex rostrata or Phragmites australis). In Wielkopolska terrestrializating peatlands, four variables determine the poor-rich gradient: conductivity, DOC, SiO₂ dissolved, Ca²⁺ and alkalinity. This study provides new data on the ecology and typology of Sphagnum peatlands in western Poland.     

Microhabitat use by larvae of the endangered dragonfly <Emphasis Type="Italic">Sympetrum pedemontanum</Emphasis><Emphasis Type="Italic">elatum</Emphasis> (Selys) in Japan

Sympetrum pedemontanum (Müller in Allioni) (Odonata: Libellulidae), which is distributed widely in the Eurasian continent and its neighboring islands, is listed as a Least Concern species in the International Union for Conservation of Nature Red List (2015). In Japan, however, the population of its subspecies S. pedemontanum elatum (Selys) has been rapidly decreasing since the 1970s. In order to conserve this subspecies, it is important to understand the seasonal microhabitat use by its larvae. However, this has been a difficult task because larvae of S. pedemontanum elatum often coexist with those of a common congener, S. eroticum (Selys), and cannot be morphologically distinguished from the latter. Thus, in this study, we first established a molecular technique based on the polymerase chain reaction to accurately identify each species. In the subsequent field survey in 2015 with its application in the Sakasegawa River, Hyogo Prefecture, we found that S. pedemontanum elatum larvae hatch in stagnant water and subsequently advance into weakly flowing water. Our results indicated a change in the microhabitats during the larval developmental process, reflecting the need for a continuous spectrum of stagnant, transitional, and flowing water. Such aquatic environments with a spectrum of water conditions are disappearing in Satoyama, a rural farming area in Japan. This has endangered species such as S. pedemontanum elatum and Oryzias latipes (Beloniformes: Adrianichthyidae) by depriving them of their favorable habitats. For their conservation, it is necessary to develop methods to recover the traditional aquatic environments in Satoyama.     

Rare, threatened and alien species in the gastropod communities in the clay pit ponds in relation to the environmental factors (The Ciechanowska Upland, Central Poland)

The objectives of the present survey were to formulate a zoocenological analysis of the gastropod communities in clay pit ponds, as well as to determine the relationships between the gastropods and their environments, and to evaluate the water habitats in terms of their ecological-conservation value. The physical and chemical parameters of water, gastropod species and macrophytes occurring in the ponds indicate mesotrophic conditions. Principal Component Analysis (PCA) reveals a correlation between gastropod density and nitrates, a correlation between gastropod density and alkalinity, and additionally shows a correlation between gastropod density and chlorides. The pond surface area, nitrates, chlorides concentrate, alkalinity, and substratum have all affected these gastropod communities. The occurrence of the first permanent population of Ferrissia clessiniana (Jickeli, 1882) was recorded in Poland. Valvata naticina Menke 1845 has become a critically rare species (CR) due to the pollution of water environments. Five other species, e.g. Anisus vorticulus (Troschel, 1834) and Planorbis carinatus O.F. Müller, 1774 are recorded on the Polish Red List of Species. The clay pit ponds of the Ciechanowska Upland, because of their distinctive environmental features, provide a refuge where a number of rare, threatened and alien gastropod species live.     

The Crested Lark Galerida cristata as an example of a bird species that benefits from agricultural management in western Poland

ABSTRACT

Capsule: The Crested Lark Galerida cristata as an example of a species which selects habitats which have undergone agricultural intensification.

Aims: To describe habitat preferences of the Crested Lark in western Poland.

Methods: We surveyed 30 randomly chosen study plots (1?km²) in western Poland to detect breeding pairs of Crested Larks. Sentinel and direct observations in the field were used to provide habitat data. Generalized linear mixed models were used to determine what type of environments habitats were selected by the Crested Larks.

Results: We recorded a total of 106 pairs of Crested Larks in 30 study plots. Birds inhabited farmland environments, where their preferred habitats included buildings, silage, and arable land with cereals.

Conclusion: Silage, which is associated with agricultural intensification within agricultural landscapes, increased the chances of the occurrence of Crested Larks.     

Elevated alkalinity and sulfate adversely affect the aquatic macrophyte Lobelia dortmanna

The increase in alkalinity and SO₄ ^2? in softwater lakes can negatively affect pristine isoetid population because the increase in alkalinity and SO₄ ^2? can stimulate sediment mineralization and consequently cause anoxia. The consequences of increased sediment mineralization depend on the ability of isoetids such as Lobelia dortmanna to oxidize the rhizosphere via radial O₂ loss. To study how alkalinity and SO₄ ^2? affect the isoetid L. dortmanna, and if negative effects could be alleviated by neighboring plants, three densities of L. dortmanna (“Low”?=?64 plants m^?2, “Medium”?=?256 plants m^?2 and “High”?=?1,024 plants m^?2) were exposed to elevated alkalinity in the water column, or a combination of both elevated alkalinity and SO₄ ^2?, and compared to a control situation. The combination of SO₄ ^2? and alkalinity significantly increased mortality, lowered areal biomass and reduced actual photosynthetic efficiency. Plant density did not significantly alleviate the negative effects caused by SO₄ ^2? and alkalinity. However, actual photosynthetic efficiency was significantly positively correlated to redox potential in the sediment, indicating a positive relationship between plant performance and sediment oxidation. The negative effects on L. dortmanna were probably caused by long periods of tissue anoxia by itself or in combination with H₂S intrusion. Therefore, increase in both SO₄ ^2? and alkalinity surface water can dramatically affect L. dortmanna populations, causing reduction or even disappearance of this icon species.     

Metarhizium: jack of all trades,master of many

The genus Metarhizium and Pochonia chlamydosporia comprise a monophyletic clade of highly abundant globally distributed fungi that can transition between long-term beneficial associations with plants to transitory pathogenic associations with frequently encountered protozoans, nematodes or insects. Some very common ‘specialist generalist’ species are adapted to particular soil and plant ecologies, but can overpower a wide spectrum of insects with numerous enzymes and toxins that result from extensive gene duplications made possible by loss of meiosis and associated genome defence mechanisms. These species use parasexuality instead of sex to combine beneficial mutations from separate clonal individuals into one genome (Vicar of Bray dynamics). More weakly endophytic species which kill a narrow range of insects retain sexuality to facilitate host–pathogen coevolution (Red Queen dynamics). Metarhizium species can fit into numerous environments because they are very flexible at the genetic, physiological and ecological levels, providing tractable models to address how new mechanisms for econutritional heterogeneity, host switching and virulence are acquired and relate to diverse sexual life histories and speciation. Many new molecules and functions have been discovered that underpin Metarhizium associations, and have furthered our understanding of the crucial ecology of these fungi in multiple habitats.     

Endemism of subterranean Diacyclops in Korea and Japan,with descriptions of seven new species of the languidoides-group and redescriptions of D. brevifurcus Ishida, 2006 and D. suoensis Ito, 1954 (Crustacea,Copepoda, Cyclopoida)

Copepods have been poorly studied in subterranean habitats in Korea. Previous records have indicated mostly the presence of species already described from Japan, with very few endemic elements. This commonality has usually been explained by repeated dispersal across the land bridges that connected the two countries several times during the Pleistocene glacial cycles. However, the Korean Peninsula is known for pockets of Cambrian and Ordovician carbonate rocks, with more than 1,000 caves already having been explored. The relative isolation of these carbonate pockets makes for an enormous speciation potential, and the development of a high level of short-range endemism of subterranean copepods should be expected. Representatives of the genus Diacyclops Kiefer, 1927 are here investigated from a range of subterranean habitats in South Korea, with comparative material sampled from central Honshu in Japan. Morphological analyses of microcharacters, many of which are used in cyclopoid taxonomy for the first time herein, reveal high diversity in both countries. No subterranean species is found in common, although the existence of four sibling species pairs in Korea and Japan may be indicative of relatively recent speciation. We describe seven new stygobiotic species, including three from Korea (Diacyclops hanguk sp. n., Diacyclops leeae sp. n., and Diacyclops parasuoensis sp. n.) and four from Japan (Diacyclops hisuta sp. n., Diacyclops ishidai sp. n., Diacyclops parahanguk sp. n., and Diacyclops pseudosuoensis sp. n.). Diacyclops hanguk, Diacyclops parasuoensis, Diacyclops ishidai, and Diacyclops parahanguk are described from newly collected material, while the other three new species are proposed for specimens previously identified as other, widely distributed species. Diacyclops brevifurcus Ishida, 2006 is redescribed from the holotype female, and Diacyclops suoensis Ito, 1954 is redescribed from material newly collected near the ancient Lake Biwa in Japan. This research provides evidence for the importance of subterranean habitats as reservoirs of biodiversity, and also demonstrates the inadequacy of current morphological methods of identifying closely related species of copepods. The disproportionately high diversity discovered around Lake Biwa provides further evidence in support of the hypothesis about the role of ancient lakes as biodiversity pumps for subterranean habitats. A key to the East Asian species of the languidoides-group is provided.     

Microbiology of diverse acidic and non-acidic microhabitats within a sulfidic ore mine

A wide variety of microhabitats within the extremely acidic abandoned underground copper mine Zlaté Hory (Czech Republic) was investigated. SSU rDNA libraries were analyzed from 15 samples representing gossan, sulfide-leaching environments in the oxidation zone, and acidic water springs in the mine galleries. Microbial analyses were extended by analyses of chemical composition of water and solid phases and identification of arising secondary minerals. The microbial communities of the three main classes of microenvironments differed in almost every aspect. Among others, ecological partitioning of Acidithiobacillus ferrooxidans and the recently described A. ferrivorans was observed. Distinct types of communities inhabiting the water springs were detected. The more extreme springs (pH?<3, conductivity?>2?mS/cm) were inhabited by “Ferrovum” spp. and A. ferrivorans, whereas Gallionella sp. dominated the less extreme ones. A new role for gossan in the extremely acidic ecosystem is proposed. This zone was inhabited by a large diversity of neutrophilic heterotrophs that appeared to be continuously washed out to the acidic environments localized downstream. Five species originating in gossan were found in several acidic habitats. Here they can survive and probably serve as scavengers of dead biomass, particularly from chemoautotrophic growths. No such process has been described from acidic mine environments so far.     

Distributions of calcareous dinoflagellate cysts in surface sediments of the western equatorial Atlantic Ocean,and their potential use in palaeoceanography

Only very few studies focus on recent calcareous dinoflagellate cyst diversity, geographic distribution and ecology, so that information on the distribution patterns and environmental affinities of individual cyst species is extremely limited. This information is, however, essential if we want to use calcareous dinoflagellate cysts for palaeoenvironmental reconstruction. Surface sediment samples from the generally oligotrophic western equatorial Atlantic Ocean, offshore northeast Brazil, were therefore quantitatively analysed for their calcareous dinoflagellate cyst content, including the calcareous vegetative coccoid Thoracosphaera heimii. Seven calcareous dinoflagellate cyst species/morphotypes and T. heimii were encountered in high concentrations throughout the area. Substantial differences in the distribution patterns were observed. The highest concentrations of cysts are found in sediments of the more oligotrophic, oceanic regions, beyond the influence of Amazon River discharge waters. Dinoflagellates producing calcareous cysts thus appear to be capable of surviving low nutrient concentrations and produce large numbers of cysts in relatively stable and predictable environments affected by minimal seasonality. To test for the environmental affinities of individual species, distribution patterns in surface sediments were compared with temperature, salinity, density and stratification gradients within the upper water column (0–100 m) over different times of the year, using principal components analysis and redundancy analysis. T. heimii and four of the seven encountered cyst species (Sphaerodinella? albatrosiana, two morphotypes of Sphaerodinella? tuberosa and Scrippsiella regalis) relate to these parameters significantly and the variations in the cyst associations appear to be associated with the different surface water currents characterising the area. The results imply that calcareous dinoflagellate cyst distributions can potentially be used to distinguish between different open oceanic environments and they could, therefore, be useful in tracing water mass movements throughout the late Quaternary.     

A Mitochondrial Phylogeny and Biogeographical Scenario for Asiatic Water Shrews of the Genus Chimarrogale: Implications for Taxonomy and Low-Latitude Migration Routes

The six species and three subspecies in the genus Chimarrogale (Soricomorpha: Soricidae) are commonly referred to as Asiatic water shrews. The Chimarrogale are the most widely distributed group of Nectogaline shrews, extending throughout the Oriental region and Japan. Because of the limited numbers of specimens available for study, the phylogenetic relationships and biogeographical history of this genus have not been comprehensively discussed. We used mitochondrial cytochrome b gene sequences to estimate phylogenetic relationships and divergence times among four Chimarrogale species, including all three subspecies of Chimarrogale himalayica. We also conducted a species delimitation analysis and tested two alternative migration scenarios in Asia through species distribution modeling and a reconstruction of the ancestral distribution. Here, we present the first proposed hypothesis regarding the Asiatic water shrew phylogeny and reveal ten putative species within the four recognized species. Distinct phylogenetic statuses of Chimarrogale phaeura, Chimarrogale platycephala, and Chimarrogale styani were confirmed. Chimarrogale himalayica was strongly supported as paraphyletic. We suggest that three subspecies of Chimarrogale himalayica should be reconsidered as distinct species. However, these suggestions must be considered with caution because only a single locus of a mtDNA gene was used. Four additional putative species, possibly distributed in central southwestern China and Taiwan, are currently undescribed; therefore, comprehensive morphological analyses are warranted to test their taxonomic statuses. The estimated molecular divergence times indicated that rapid speciation occurred during the early Pliocene, and current distribution patterns may have been affected by global cooling during the Pliocene/Pleistocene boundary. Reconstruction of the ancestral distribution and species distribution modeling for Asiatic water shrews revealed a low-latitude migration route over which ancestral Chimarrogale migrated from Europe via Central Asia to their current distribution. Our results demonstrated that Asiatic water shrews could have evolved throughout the low-latitude migration route from Europe to East and Southeast Asia.     

Spatial relationships in a dendritic network: the herpetofaunal metacommunity of the Mattole River catchment of northwest California

We investigated the aquatic and riparian herpetofauna in a 789 km² river catchment in northwest California to examine competing theories of biotic community structuring in catchment stream networks. Research in fluvial geomorphology has resulted in multi‐scale models of dynamic processes that cyclically create, maintain, and destroy environments in stream networks of mountain catchments. These models have been applied to understanding distributions of invertebrates, algae, fishes and their habitats across entire basin networks, but similar approaches with herpetofauna are rare. We examined multi‐scale spatial patterns of multiple species as they related to variation in channel types, channel settings, and within‐channel attributes that result from these processes. From 83 reaches distributed randomly throughout the watershed, we distinguished four channel types: 1) high gradient with cascade structure; 2) 2–4% gradient with step‐pool structure controlled by moderately steep valleys; 3) slightly entrenched, lower gradient, plane‐bed structure; and 4) low gradient, shallow, unconfined, multiple or migrating pool/riffle channels in broad alluvial valleys. The composition of herpetofauna differed in five of six pair‐wise comparisons among these channel types, indicating a minimum of three distinct mesoscale assemblages. We used non‐parametric multiple regression (NPMR) to examine relationships at multiple spatial scales. NPMR revealed species‐specific associations with channel settings and within‐channel environments among species sharing the same sets of channel types. Morphological adaptations, biophysical limits and natural histories of each species best explained their associations with distinct sets of attributes surrounding and within channel types. While each set of species has similarly adapted to fluvial and geomorphic disturbance processes structuring channels at the mesoscale, species within each set have adapted to a unique set of attributes that are best discerned when their spatial relationships are examined across multiple spatial scales. We evaluated the various spatial patterns against hypotheses of stream community organization and metacommunity perspectives.     

Influence of environmental variables on algal associations from a floating vegetation mat (Schwingmoor Lake Lunzer Obersee,Austria)

In 2002, periphyton samples were collected 14 times from six stations within a floating vegetation mat in Lake Lunzer Obersee, a small mountain lake in Austria. Water temperature, conductivity, pH, alkalinity, Ca²⁺- and total-hardness were measured and quantitative samples were taken for algal biomass and chlorophyll-a analysis. Algal biomass results clearly indicated the dominance of green algae. Cluster analyses were carried out, based on both algal data and environmental parameters. The algal data separated sites, whereas the abiotic clustering revealed a temporal aspect. An indicator species analysis determined the characteristic taxa for each species group. Indicator species were then related to environmental factors using a redundancy analysis (RDA). Both pH and conductivity were significant factors, whereas water temperature, alkalinity, Ca²⁺- and total-hardness were not. The results of the RDA show that three species groups could be identified along a gradient of pH. One group was positively correlated with high alkalinity and another group occurred at higher values of conductivity.     

Patterns and governing forces in aquatic microbial communities

In this review we survey recent publications employing molecular techniques to investigate the distribution of microbial species in aquatic environments. We analyzed the occurrence of microbial phyla in freshwater and marine habitats and observed patterns of distribution that could be explained by the adaptation of microorganisms to physical and biological parameters that vary in aquatic habitats. The gram-positive bacteria, the Verrucomicrobiales and the - and -subdivisions of the Proteobacteria are distributed throughout a range of aquatic habitats, while other phylogenetic groups appear to be adapted to more narrowly defined environmental niches such as anoxic water and sediments (-Proteobacteria) or floating aggregates (Cytophaga-Flexibacter-Bacteroides phylum). -proteobacterial sequence types have been detected throughout freshwater habitats, but these organisms are largely absent from open ocean environments. Within several of these divisions, clusters of closely related small sub unit ribosomal RNA sequence types have been detected in geographically disparate environments, suggesting that some microbial species are globally distributed. In addition to physical variables such as salinity and pH, biological variables also influence microbial community composition. This was illustrated by changes that occurred in the eukaryotic and bacterial species composition in laboratory mesocosms after a viral outburst. We conclude that physical and biological forces govern the composition of aquatic microbial communities and result in divergent evolutionary histories of the indigenous microbial species.     

Environmental determinants of the small mammal assemblage in an agroecosystem of central Argentina: The role of Calomys musculinus

Agricultural intensification in the central region of Argentina has been accompanied by rodent assemblage changes, involving an increase in Calomys species densities. In particular, Calomys musculinus, the main reservoir of Junín virus (etiological agent of the Argentine Haemorrhagic Fever, AHF) selects field borders over crop-fields. Borders represent relatively-stable habitats within agroecosystems, otherwise highly human modified landscapes. In this article, we assessed the effect of environmental variables on rodent species occurrence and assemblage in the field borders of a pampean agroecosystem. Small rodent occurrence was examined for variation according to vegetation species composition, structure and productivity, using canonical ordination techniques. In a total of 72 crop-field borders of Córdoba province, in spring, summer and autumn (2005-2006), we captured 1041 rodents of 8 different species. Akodon azarae, Calomys venustus and C. musculinus were the dominant species of the assemblage, with the first two associated one another, while C. musculinus tended to be related to different environmental variables. We showed that rodent species associations were mediated by resources that changed seasonally, such as vegetation cover. Also, the strength and “sign” of the association between species seemed to be a consequence of different habitat preferences and activity patterns. Finally, the intra-annual population cycle seemed to influence the relation between species and habitat structure and, possibly, inter-specific competition for resources. Therefore, we suggest that less generalist species of the rodent assemblage, well adapted to linear habitats, may limit C. musculinus occurrence throughout the agroecosystem by habitat and spatial competition. Any action aimed to control AHF, and therefore C. musculinus population density, should exclude negative effects on coexisting species.     

Impact of hard-bottom substrata on the small-scale distribution of fish and decapods in shallow subtidal temperate waters

The micro-scale spatial distribution patterns of a demersal fish and decapod crustacean assemblage were assessed in a hard-bottom kelp environment in the southern North Sea. Using quadrats along line transects, we assessed the in situ fish and crustacean abundance in relation to substratum types (rock, cobbles and large pebbles) and the density of algae. Six fish and four crustacean species were abundant, with Ctenolabrus rupestris clearly dominating the fish community and Galathea squamifera dominating the crustacean community. Differences in the substratum types had an even stronger effect on the micro-scale distribution than the density of the dominating algae species. Kelp had a negative effect on the fish abundances, with significantly lower average densities in kelp beds compared with adjacent open areas. Averaged over all of the substrata, the most attractive substratum for the fish was large pebbles. In contrast, crustaceans did not show a specific substratum affinity. The results clearly indicate that, similar to other complex systems, significant micro-scale species–habitat associations occur in northern hard-bottom environments. However, because of the frequently harsh environmental conditions, these habitats are mainly sampled from ships with sampling gear, and the resulting data cannot be used to resolve small-scale species–habitat associations. A detailed substratum classification and community assessment, often only possible using SCUBA diving, is therefore important to reach a better understanding of the functional relationships between species and their environment in northern temperate waters, knowledge that is very important with respect to the increasing environmental pressure caused by global climate change.