Remote sensing-derived land surface temperature trends over South Asia

Spatiotemporal changes in land surface temperature (LST) over South Asia were estimated using MODIS (moderate resolution imaging spectroradiometer) data from 2000 to 2021. We calculated the monthly and annual LST trends and magnitudes by applying the Mann–Kendall test and Sen's slope estimator at both ecoregion and pixel level. More ecoregions experienced daytime cooling than warming. Central and west South Asia showed the highest daytime cooling in December compared to the nighttime warming in the central and northwest in July and September. Nineteen ecoregions demonstrated monthly daytime cooling trends at the 99% confidence level (CL), with the highest record observed in ecoregion ‘Indus Valley desert’ in March with the magnitudes of −0.26 °C/yr. While the monthly and annual nighttime warming magnitude was the maximum in ‘Gissaro-Alai open woodlands’ in December (0.19 °C/yr at 95% CL), and ‘Indus River Delta-Arabian Sea mangroves’ at annual scale (0.06 °C/yr at 99% CL). To understand the influence of large-scale atmospheric oscillations on the trends, we also correlated the estimated LST trends with the selected oscillation indices. Sea surface temperature (SST) Niño 3.4 showed the most significant influence on the trends, where it was positively correlated with 38 ecoregions during nighttime over the year. A better understanding of temperature trends and impacts on South Asia would guide sustainable development and ensures the excessive demands on food, water, and energy supplies coping with the growing population.     

NORTH ATLANTIC RIGHT WHALE DISTRIBUTION IN RELATION TO SEA-SURFACE TEMPERATURE IN THE SOUTHEASTERN UNITED STATES CALVING GROUNDS

Standardized aerial surveys were used to document the winter (December–March) distribution of North Atlantic right whales in their calving area off the coasts of Georgia and northeastern Florida (1991–1998). Survey data were collected within four survey zones in and adjacent to federally designated critical habitat. These data, including whale‐sighting locations and sampling effort, were used to describe right whale distribution in relation to sea‐surface temperature (SST) from satellite‐derived images. Locations where whales were sighted (n= 609) had an overall mean SST of 14.3°C ± 2.1° (range 8°–22°C). Data from two survey zones having sufficient data (including the “early warning system” (EWS) zone and the Florida nearshore) were pooled by season and stratified by month to investigate changes in monthly ambient SST and fine‐scale distribution patterns of right whales in relation to SST within spatially explicit search areas. Using Monte Carlo techniques, SSTs and latitudes (means and standard deviations) of locations where whales were sighted were compared to a sampling distribution of each variable derived from daily‐search areas. Overall, results support a nonrandom distribution of right whales in relation to SST: during resident months (January and February), whales exhibited low variability in observed SST and a suggested southward shift in whale distribution toward warmer SSTs in the EWS zone; while in the relatively warmer and southernmost survey zone (Florida nearshore), right whales were concentrated in the northern, cooler portion. Our results support that warm Gulf Stream waters, generally found south and east of delineated critical habitat, represent a thermal limit for right whales and play an important role in their distribution within the calving grounds. These results affirm the inclusion of SST in a multivariate predictive model for right whale distribution in their southeastern habitat.     

Large-scale spatial distribution patterns of echinoderms in nearshore rocky habitats

This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m(2) quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m(-2). In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m(2) quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m(-2). Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a network of environmental and ecological processes, and by the differing responses of various echinoderm taxa, making generalizations about the patterns of nearshore rocky habitat echinoderm assemblages difficult.     

Paleoceanographic evolution of North Pacific surface water off Japan during the past 150,000 years

Hydrographic variability in the Mixed Water Region of the Northwest Pacific Ocean at latitudes 35°–40°N, between the Kuroshio Extension and Oyashio Front, causes complex upwelling, leading to large primary productivity and thus great fishery resources. We reconstructed the periodicity of the variability in North Pacific Intermediate Water upwelling and surface ocean hydrography based on the high-resolution analysis of diatom assemblages in seven cores, representing the last 150,000 years. We derived annual sea surface temperatures (SSTs) through a diatom-based proxy (Td′). The Td′-derived annual SSTs (°C) are controlled by orbital forcing, and show a reversed saw-tooth in southern cores, in contrast to a normal saw-tooth pattern in the northern cores. Oceanic diatom abundances along the northern margin of the Mixed Water Region are twice times as high as beneath the axis of the Kuroshio Extension, and fluctuated in a revised saw-tooth pattern with higher overall abundances interglacials. After the last deglaciation, annual SSTs declined markedly during Heinrich and Bond events in the northern North Atlantic, when ice-rafted detritus transported by icebergs was abundant. Wavelet analyses of the record of oceanic diatom abundances show significant variability at 2.0-kyr, 2 to 5.6-kyr and 3.2 to 9.6-kyr periods. Wavelet analyses of the annual SST records show significant periodicity at 1.4 to 2.6-kyr, 3.3 to 4.0-kyr, 7.2 to 12.8-kyr cycles.     

Warming off southwestern Japan linked to distributional shifts of subtidal canopy‐forming seaweeds

To assess distributional shifts of species in response to recent warming, historical distribution records are the most requisite information. The surface seawater temperature (SST) of Kochi Prefecture, southwestern Japan on the western North Pacific, has significantly risen, being warmed by the Kuroshio Current. Past distributional records of subtidal canopy‐forming seaweeds (Laminariales and Fucales) exist at about 10‐year intervals from the 1970s, along with detailed SST datasets at several sites along Kochi's >700 km coastline. In order to provide a clear picture of distributional shifts of coastal marine organisms in response to warming SST, we observed the present distribution of seaweeds and analyzed the SST datasets to estimate spatiotemporal SST trends in this coastal region. We present a large increase of 0.3°C/decade in the annual mean SST of this area over the past 40 years. Furthermore, a comparison of the previous and present distributions clearly showed the contraction of temperate species' distributional ranges and expansion of tropical species' distributional ranges in the seaweeds. Although the main temperate kelp Ecklonia (Laminariales) had expanded their distribution during periods of cooler SST, they subsequently declined as the SST warmed. Notably, the warmest SST of the 1997–98 El Niño Southern Oscillation event was the most likely cause of a widespread destruction of the kelp populations; no recovery was found even in the present survey at the formerly habitable sites where warm SSTs have been maintained. Temperate Sargassum spp. (Fucales) that dominated widely in the 1970s also declined in accordance with recent warming SSTs. In contrast, the tropical species, S. ilicifolium, has gradually expanded its distribution to become the most conspicuously dominant among the present observations. Thermal gradients, mainly driven by the warming Kuroshio Current, are presented as an explanation for the successive changes in both temperate and tropical species' distributions.     

Amazon Basin climate under global warming: the role of the sea surface temperature

The Hadley Centre coupled climate-carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5 degrees C warmer air temperature associated with a global mean SST warming.     

江苏沿江和江淮区褐飞虱前期迁入量与太平洋海温场的遥相关及其可能机制

为筛选出有效的长期预测因子,对江苏通州和江苏淮安褐飞虱前期迁入量与太平洋海温场遥相关时空分布分别进行了相关分析及其稳定性检验。结果表明： 与褐飞虱前期迁入量连续稳定显著相关的海温区,在空间上主要分布在中太平洋和南太平洋（72.4%）,在时间上主要分布在前两年和前一年（82.7%）。分别分析褐飞虱前期迁入量与当年4-8月上旬各旬降水量、平均温度、当年1-8月500 hPa西太平洋副高月平均指数之间的两两相关关系,并比较这三者与前期太平洋海温场遥相关时空分布的异同。根据对两地的个例分析表明：前一冬春季赤道中东太平洋海温的变化引起当年6月副高面积指数的变化,影响江苏通州当年6月下旬降水,从而影响江苏通州褐飞虱的前期迁入量;前两年春夏季赤道中东太平洋海温的变化引起当年5月副高北界位置的变化,影响江苏淮安当年7月上旬降水,从而影响江苏淮安褐飞虱的前期迁入量。在此基础上,对褐飞虱前期迁入量与太平洋海温场遥相关的可能机制提出“海温→大气环流（副高）→气候→褐飞虱前期迁入"的一般假想模式。     

Hierarchical partitioning of ant diversity: implications for conservation of biogeographical diversity in arid and semi‐arid areas

Aim The scale of observation is important in detecting the spatial variation of biological assemblages, which should be taken into consideration for an appropriate plan of biogeographical conservation. We investigated whether (1) World Wildlife Fund’s ecoregion units are the appropriate scale for conserving ant diversity in Iran, (2) each ecoregion represents a distinct ant community composition and (3) patterns of diversity partitioning differ among four ecoregions. Location Iran, a sampling transect along four arid and semi‐arid ecoregions. Methods We applied hierarchical partitioning to data collected from a nested sampling design including four hierarchical levels: ‘local’, ‘landscape’, ‘ecoregional’ and ‘whole‐region’. Observed alpha and beta diversity components were compared with values of null distributions. Hierarchical cluster analysis was applied to evaluate similarity of ant species composition among ecoregions. Results Partitioning of whole‐region species richness showed that 85% of the species richness was generated by beta diversity among ecoregions and landscapes. The highest value of diversity was generated by beta diversity among ecoregions. Unlike whole‐region partitioning, separate partitioning within each ecoregion revealed that beta component among localities contributed to species richness of each ecoregion. Ecoregions showed different patterns of diversity partitioning. The alpha component contributed largely to the total diversity of two ecoregions, but for two other ecoregions, beta component contributed more than alpha component. Cluster analysis identified four discrete ant species compositions; however, it split landscapes of one ecoregion into two distinct groups. Main conclusions Whole‐region diversity partitioning indicates that ecoregions represent the appropriate scale for conserving ant diversity and that each ecoregion has a distinct ant fauna. However, different conservation strategies should be considered for different ecoregions owing to the differing scales of variation within them. Boundaries of ecoregions remain a subject for further studies. The influence of climate change on ecoregional boundaries should be considered and should be predicted with respect to future conservation maps.     

渭河底栖动物性状和功能对空间尺度环境变量响应的生态区差异性

以我国中部渭河南部流域山区和平原生态区的底栖动物为研究对象,通过计算29个生物性状类别和7个功能多样性指数,比较了不同生态区的生物性状组成和功能与性状多样性指数差异性;应用综合RLQ和fourth-corner方法探索底栖动物生物性状组成与土地利用和理化变量的关系;通过广义线性模型(GLM)比较不同空间尺度环境变量对底栖动物功能与性状多样性指数影响的生态区差异性。研究发现,共18个底栖动物性状组成在山区和平原间存在显著差异性,其中具有无庇护所和以叶片为庇护所材料、外骨骼轻微骨化和骨化良好、草食性、捕食性等生物性状的底栖动物栖息于栖境状况较好的山区,体壁呼吸、虫体柔软、集食者等生物性状更多的集中在人类活动较严重的平原区。除了功能均匀度指数外,山区的性状和功能多样性指数均显著高于平原,说明平原环境干扰显著降低了底栖动物性状和功能多样性。综合RLQ和fourth-corner方法表明底栖动物生物性状对环境胁迫的响应存在可预测性。GLM模型结果表明,山区和平原生物性状和功能多样性指数受到不同空间尺度土地利用和理化环境变量的影响:流域尺度城镇用地、水温和TN含量是影响山区功能和性状多样性指数模型的重要环境变量,但平原区河段尺度农业用地面积百分比和平均水深是影响功能和性状多样性的主要因子。     

A freshwater ecoregion delineation approach based on freshwater macroinvertebrate community features and spatial environmental data in Taizi River Basin, northeastern China

The ecoregion is currently widely used as the basic geospatial unit in freshwater biodiversity conservation. The popularly used delineation is usually based on the assumption that attributes of aquatic ecosystems are influenced by landscape-scale environmental variables. However, few ecoregion delineations attempt to establish the local validity of this assumption prior to delineation, and few studies check the correspondence of the derived ecoregion boundaries with the distributions of attributes of aquatic biota. In this study, we established an approach to overcome these shortcomings. The notable features of the approach are: (1) the delineation variables were filtered through a series of analytical steps to select those that best represented the aquatic community traits, and which avoided redundancy in the data; (2) the method was quantitative and repeatable; and (3) the derived ecoregion boundaries were checked for consistency with the spatial attributes of aquatic biota. The approach was applied in the Taizi River Basin, northeast China. The procedure proposed here filtered out altitude and annual precipitation as the best variables to include in the freshwater ecoregion delineation. Then, using the quantitative ISODATA classification method, the basin was classified into three ecoregions. A test of accuracy indicated that freshwater ecoregions matched well with the spatial distribution pattern of macroinvertebrate community attributes. Statistical analysis showed that natural geographical attributes and river attributes were different in the three ecoregions, and indices representing macroinvertebrate community attributes are significantly different as a whole among the three ecoregions. The case study proved this approach effective on ecoregion delineation.     

Influence of physiographic and climatic factors on spatial patterns of acorn production in Maryland and Virginia,USA

Aim The aims of this study were to identify the effects physiographic differences have on the spatial synchrony of acorn production within red (Quercus rubra) and white (Quercus alba) oak subgenus groups, to identify climatic factors associated with acorn production patterns, and to assess if and how these relationships vary across a distinct physiographic boundary. Location Maryland and Virginia in the eastern United States. Methods Using data from 36 survey sites in Virginia (1973–2000) and Maryland (1977–2000), we described the spatial synchrony of annual acorn production based on Mantel tests and modified correlograms at three spatial scales: (1) the entire study area, (2) within two ecological regions (mountain and Piedmont), and (3) between these ecoregions. Using climate data obtained from the National Climate Data Centre, we described the relationship between climate and acorn production within each ecological region using linear regression. Results Spatial synchrony in the white oak group acorn production was strong among sites closest together, and declined with distance. The average April temperature during the year of acorn drop was positively related to acorn crop size within the mountain and Piedmont ecoregions. Spatial synchrony in the red oak group was strong among sites closest together and declined with distance in the mountain region. Synchrony was weaker in the Piedmont than in the mountain ecoregion and declined slightly with increasing distance. Between the mountain and Piedmont ecoregions, synchrony was not detected among the closest sites, but was detected with increasing strength as the distance between site pairs increased. In the Piedmont ecoregion, the number of April freeze events and total July precipitation, both 2 years prior to acorn drop, were negatively related to red oak acorn production. In the mountains, average July temperature 2 years prior to acorn drop was positively related to acorn production. Main conclusions Physiographic differences affected the spatial acorn production synchrony in the red oak but not in the white oak subgenus group. Climatic factors related to annual acorn production variability differed between subgenus groups and physiographic regions. The physiographic differences between the mountain and Piedmont ecoregions may define spatial patterns of acorn production synchrony in some oak species and mediate climatic influences on acorn production.     

Ecological biogeography of Malagasy non‐volant mammals: community structure is correlated with habitat

Aim To examine the relationship between ecoregions, as a proxy for regional climate and habitat type, and mammalian community structure, defined by species composition and richness (e.g. taxonomic structure) and ecological diversity (e.g. ecological structure) of non‐volant species. Location Madagascar. Methods Faunal lists of non‐volant mammal species occurring in 35 communities from five World Wildlife Fund ecoregions were collected from published and unpublished sources. Species were assigned to ecological groups defined by trophic status, locomotor habits, activity cycle and body mass. We used Mantel tests, cluster analysis and principal coordinates analysis to evaluate geographic patterning in taxonomic composition and species richness. We used stepwise multiple discriminant analysis to characterize patterns in the ecological diversity of the mammalian communities from each ecoregion. Communities from transitional habitats (e.g. representing more than one ecoregion) were used to test the predictive power of the analyses. Results Non‐volant mammal communities divided into clusters that correspond to ecoregions. There was a strong distance effect in the taxonomic structure of communities across the island and within both humid and dry forest communities, but this effect was weak within humid forest communities. Mammalian species richness was significantly lower in dry forest than in humid forest communities. The ecological structure of communities was also correlated with ecoregions. Changes in the relative percentages of omnivory, arboreal quadrupedalism, terrestrial/arboreal quadrupedalism and two body mass classes accounted for 98.1% of the variation in ecological structure. Transitional communities were projected in intermediate positions by the discriminant model. Main conclusions Our analysis demonstrates that the broad‐scale habitat and climate variables captured by the ecoregion model have shaped the assembly of non‐volant mammal communities in Madagascar over evolutionary time. The spatial pattern is consistent with ecological sorting of species ranges along environmental gradients. Historical processes, such as recent extinction and migration, may have also affected the structure of mammal communities, although these factors have played a secondary role.     

Phylogeography of Ramalina menziesii,a widely distributed lichen‐forming fungus in western North America

The complex topography and climate history of western North America offer a setting where lineage formation, accumulation and migration have led to elevated inter‐ and intraspecific biodiversity in many taxa. Here, we study Ramalina menziesii, an epiphytic lichenized fungus with a range encompassing major ecosystems from Baja California to Alaska to explore the predictions of two hypotheses: (i) that the widespread distribution of R. menziesii is due to a single migration episode from a single lineage and (ii) that the widespread distribution is due to the formation and persistence of multiple lineages structured throughout the species' range. To obtain evidence for these predictions, we first construct a phylogenetic tree and identify multiple lineages structured throughout the species' range – some ancient ones that are localized and other more recent lineages that are widely distributed. Second, we use an isolation with migration model to show that sets of ecoregion populations diverged from each other at different times, demonstrating the importance of historical and current barriers to gene flow. Third, we estimated migration rates among ecoregions and find that Baja California populations are relatively isolated, that inland California ecoregion populations do not send out emigrants and that migration out of California coastal and Pacific Northwest populations into inland California ecoregions is high. Such intraspecific geographical patterns of population persistence and dispersal both contribute to the wide range of this genetically diverse lichen fungus and provide insight into the evolutionary processes that enhance species diversity of the California Floristic Province.     

Diatom-derived SSTs (Td′ ratio) indicate warm seas off Japan during the middle Holocene (8.2–3.3 kyr BP)

Regression analysis was performed between the ratio of warm- and cold-water diatoms (Td′ ratio) in 123 surface sediment samples in the northwest Pacific Ocean and the mean annual sea surface temperatures (SSTs) (°C) at the core sites, in order to calibrate this proxy for paleo-temperatures. Equations to derive annual SST (°C) from diatom analysis were somewhat different for the Tohoku area (y = 6.5711⁎ × ^0.273, r = 0.89946) than for the Japan Sea (y = 5.4069⁎ × ^0.26841, r = 0.89088). The annual paleo-SSTs (°C) in the Tohoku Area were in general higher than in the Japan Sea despite lower Td′ values, because the warm-water species Fragilariopsis doliolus is abundant only in the Tsushima Warm Current in the Japan Sea. The reliability of the equations is supported by our understanding of the ecology of recent diatoms. Td′-derived annual paleo-SSTs (°C) agree with alkenone-derived summer paleo-SST (°C) at a site off central Japan in the northwestern Pacific. In a south-to-north transect of cores around Honshu and Hokkaido, paleo-SSTs (°C) decreased when the Kuroshio and Tsushima Warm Currents weakened. The middle Holocene (8.2–3.3 cal kyr BP) was warmer by 1–2 °C than earlier and later parts of the Holocene, and mean annual paleo-SSTs (°C) show rhythmic fluctuations with durations of 1000 years and 400–500 years. These new data show that annual SSTs were warm in the northwestern Pacific at times that the northeastern Pacific was cold. In addition, oceanic warm- and cold-water species defined by Kanaya and Koizumi [Kanaya, T., Koizumi, I., 1966. Interpretation of diatom thanatocoenoses from the North Pacific applied to a study of core V20–130 (studies of a deep-sea core V20–130, part IV). Sci. Rep. Tohoku Univ., 2nd series (Geol.) 37, 89–130], and Koizumi et al. [Koizumi, I., Irino, T., Oba, T., 2004. Paleoceanography during the last 150 kyr off central Japan based on diatom floras. Mar. Micropaleontol. 53, 293–365] are illustrated.     

Climatic control of upwelling variability along the western North-American coast

The high biological production of the California Current System (CCS) results from the seasonal development of equatorward alongshore winds that drive coastal upwelling. While several climatic fluctuation patterns influence the dynamics and biological productivity of the CCS, including the El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation index (PDO) and the North Pacific Gyre Oscillation (NPGO), the mechanisms of interaction between climatic oscillations and the CCS upwelling dynamics have remained obscure. Here, we use Singular Spectral Analysis (SSA) to reveal, for the first time, low-frequency concordance between the time series of climatic indices and upwelling intensity along the coast of western North America. Based on energy distributions in annual, semiannual and low-frequency signals, we can divide the coast into three distinct regions. While the annual upwelling signal dominates the energy spectrum elsewhere, low-frequency variability is maximal in the regions south of 33°N. Non-structured variability associated with storms and turbulent mixing is enhanced at northerly locations. We found that the low-frequency signal is significantly correlated with different climatic indices such as PDO, NPGO and ENSO with the correlation patterns being latitude-dependent. We also analyzed the correlations between this upwelling variability and sea surface temperature (SST) and sea level pressure (SLP) throughout the North Pacific to visualize and interpret the large-scale teleconnection dynamics in the atmosphere that drive the low-frequency coastal winds. These results provide new insights into the underlying mechanisms connecting climatic patterns with upwelling dynamics, which could enhance our prediction and forecast capabilities of the effects of future oceanographic and climatic variability in the CCS.     

Biogeographical patterns of rocky intertidal communities along the Pacific coast of North America

Aim Our aim in this paper is to present the first broad‐scale quantification of species abundance for rocky intertidal communities along the Pacific coast of North America. Here we examine the community‐level marine biogeographical patterns in the context of formerly described biogeographical regions, and we evaluate the combined effects of geographical distance and environmental conditions on patterns of species similarity across this region. Location Pacific coast of North America. Methods Data on the percentage cover of benthic marine organisms were collected at 67 rocky intertidal sites from south‐eastern Alaska, USA, to central Baja California Sur, Mexico. Cluster analysis and non‐metric multidimensional scaling were used to evaluate the spatial patterns of species similarity among sites relative to those of previously defined biogeographical regions. Matrices of similarity in species composition among all sites were computed and analysed with respect to geographical distance and long‐term mean sea surface temperature (SST) as a measure of environmental conditions. Results We found a high degree of spatial structure in the similarity of intertidal communities along the coast. Cluster analysis identified 13 major community structure ‘groups’. Although breaks between clusters of sites generally occurred at major biogeographical boundaries, some of the larger biogeographical regions contained several clusters of sites that did not group according to spatial position or identifiable coastal features. Additionally, there were several outliers – sites that grouped alone or with sites outside their region – for which localized features may play an important role in driving community structure. Patterns of species similarity at the large scale were highly correlated with geographical distance among sites and with SST. Importantly, we found community similarity to be highly correlated with long‐term mean SST while controlling for the effects of geographical distance. Main conclusions These findings reveal a high degree of spatial structure in the similarity of rocky intertidal communities of the north‐east Pacific, and are generally consistent with those of previously described biogeographical regions, with some notable differences. Breaks in similarity among clusters are generally coincident with known biogeographical and oceanographic discontinuities. The strong correlations between species similarity and both geographical position and SST suggest that both geography and oceanographic conditions have a large influence on patterns of intertidal community structure along the Pacific coast of North America.     

Fish ecoregions of Kansas: stream fish assemblage patterns and associated environmental correlates

Synopsis Principal components analysis was performed on fish presence/absence data for 39 common fish species from 410 stream sites in Kansas. The analysis confirmed ten ecologically meaningful fish assemblages, based on species associations. Factor scores based on these assemblages were then clustered into six geographic areas or fish ecoregions. Canonical discriminant analysis identified environmental variables that distinguished the derived fish ecoregions. Mean annual runoff, mean annual growing season, and discharge appear most important. Mean width, mean depth, chloride concentration, water temperature, substrate type, gradient, and percent of pool habitat were less important. Correspondence exists between these fish ecoregions and the patterns of physiographic regions, river basins, geology, soil, and potential natural vegetation in Kansas. The multivariate statistical approach used to classify fish ecoregions should have considerable potential value for fish assessment and management purposes in areas other than the state of Kansas.     

Localized temperature adaptation of cottonwoods from elevational ecoregions in the Rocky Mountains

To investigate temperature adaptation of cool-climate trees, we studied 14 cottonwood genotypes from riparian (streamside) zones in three ecoregions differing in elevation in the Rocky Mountains of Alberta, Canada. Black cottonwoods (Populus trichocarpa) were collected from the higher, cooler montane and intermediate (aspen) parkland, and narrowleaf cottonwoods (P. angustifolia) were collected from the lower, warmer fescue prairie. The genotypes were grown in growth chambers under three temperature regimes reflecting the ecoregion variation. Sapling growth (dry weight) varied significantly across temperatures and for the genotypes from within and particularly across the ecoregions. Significant temperature × genotype interactions further indicated differentiation of the temperature response. Growth of the montane clones increased by 209% between 15/10 and 20/15°C and was 37% lower at 25/20°C. In contrast, genotypes from the lower ecoregions grew more slowly at the cool and intermediate temperatures (59 and 58% of montane) and then demonstrated constant (−3% parkland) or slightly increased (+16% prairie) growth at 25/20°C. This suggests the existence of P. trichocarpa ecotypes, localized populations with different temperature responses. This differentiation may explain our previous observation of comparable growth across these ecoregions despite substantial temperature variation, and the existence of ecotypes would produce a range of responses to climate warming that should produce an upward shift of the mountain ecoregions.     

Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

We explored the possible effects of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) on interannual sea surface temperature (SST) variations in the Alborán Sea, both separately and combined. The probability of observing mean annual SST values higher than average was related to NAO and AO values of the previous year. The effect of NAO on SST was negative, while that of AO was positive. The pure effects of NAO and AO on SST are obscuring each other, due to the positive correlation between them. When decomposing SST, NAO and AO in seasonal values, we found that variation in mean annual SST and mean winter SST was significantly related to the mean autumn NAO of the previous year, while mean summer SST was related to mean autumn AO of the previous year. The one year delay in the effect of the NAO and AO on the SST could be partially related to the amount of accumulated snow, as we found a significant correlation between the total snow in the North Alborán watershed for a year with the annual average SST of the subsequent year. A positive AO implies a colder atmosphere in the Polar Regions, which could favour occasional cold waves over the Iberian Peninsula which, when coupled with precipitations favoured by a negative NAO, may result in snow precipitation. This snow may be accumulated in the high peaks and melt down in spring-summer of the following year, which consequently increases the runoff of freshwater to the sea, which in turn causes a diminution of sea surface salinity and density, and blocks the local upwelling of colder water, resulting in a higher SST.     

Sea surface temperature and the growth of the West Atlantic reef-building coral Montastraea annularis

Relationships were analyzed between sea surface temperature (SST) and annual growth characteristics (density, extension rate and calcification rate) of the Caribbean reef-building coral Montastraea annularis. Colonies were collected from 12 localities in the Gulf of Mexico and the Caribbean Sea. Two well-separated relationships were found, one for the Gulf of Mexico and the other for the Caribbean Sea. Calcification rate and skeletal density increased with increasing SST in both regions, while extension rate tended to decrease. Calcification rate increased ∼0.57 g cm⁻² year⁻¹ for each 1 °C increase in SST. Zero calcification was projected to occur at 23.7 °C in corals from the Gulf of Mexico and at 25.5 °C in corals from the Caribbean Sea. The 24 °C annual average SST isotherm marks the northern limit of distribution of M. annularis. Montastraea annularis populations of the Gulf of Mexico are isolated from those of the Caribbean Sea, and results indicate that corals from the Gulf of Mexico are adapted to growth at lower minimum and average annual SST. Corals from both the Gulf of Mexico and the Caribbean Sea, growing at lower SSTs and having lower calcification rates, extend their skeletons the same or more than those growing at higher SSTs. They achieve this by putting more of their calcification resources into extension and less into thickening, i.e., by sacrificing density.