Spatial Patterns Of Abundance Research Articles

Do ecological traits of low abundance and niche overlap promote hybridisation among coral-reef angelfishes?

Hybridisation among species of coral-reef fish was previously considered to be rare. However, recent studies have revealed that hybridisation is prevalent in coral-reef fish, highlighting the need to understand the causes of this process. The angelfishes (family Pomacanthidae) have the greatest proportion (~ 30%) of hybridising species to date, with 26 species reported to hybridise. The aim of this study was to examine ecological factors (rarity of parent species and niche overlap) that promote hybridisation in terrestrial environments and to test these factors in the marine environment by examining hybridising angelfishes at Christmas Island (Indian Ocean). Three species of pygmy angelfish (Centropyge flavissima, C. eibli, and C. vrolikii) and their hybrids were investigated to address three objectives: (1) to determine temporal and spatial patterns in abundance and whether these patterns are linked to environmental factors; (2) to test for overlapping patterns in habitat use; and (3) to test for overlapping patterns in diet. Based on 14 yr of surveys, C. flavissima was abundant (4.53 individuals per 250 m2 ± 0.66), whereas C. eibli, C. vrolikii, and all hybrid combinations were consistently rare (average abundance < 0.3 per 250 m2 ± 0.03). Parent species and their hybrids were more abundant at 20 m depth compared to 5 m. All species and their hybrids had similar patterns of abundance around Christmas Island, with significantly high abundances evident at the most sheltered sites. Parent species and their hybrids also had similar diets that comprised a mix of green, red, and brown algae. The rarity of parent species, their niche overlap, and the haremic reproductive strategy likely promote hybridisation in angelfishes at Christmas Island. This study provides empirical evidence that hybridisation in reef fishes conforms to terrestrial-based hypothesis, and thus advances our understanding of the processes underlying hybridisation in coral-reef systems.

Multiple environmental gradients influence the distribution and abundance of a key forest-health indicator species in the Southern Appalachian Mountains, USA

The effects of global climate change are threatening biodiversity, with particular concern for amphibians, whose survival often depends on specific abiotic conditions. To predict how future climate change will affect amphibian populations, it is first necessary to understand how patterns of abundance are shaped by multiple environmental conditions at both local and regional scales. Plethodontid salamander are a group of lungless ectotherms that require cool and moist habitats to survive. While the broad elevational distribution and abundance patterns are well-understood, other important abiotic gradients exist within montane systems that are contributing to fine-scale spatial abundance patterns. We aim to assess the fine-scale spatial abundance of a plethodontid salamander across two key environmental gradients: temperature and moisture. We conducted area-constrained repeated point-count surveys at plots situated across temperature and moisture gradients in western North Carolina. Each plot was surveyed on 4 occasions, and site and survey-level covariates were measured. We found heterogeneous abundance patterns across these two gradients whereby warmer low elevations contain the greatest abundance near stream sides, where conditions are cooler and wetter than the regional landscape. At cooler, higher elevations, salamanders are distributed more uniformly across the broader landscape, likely as a result of the suitable regional climate. Fine-scale habitat associations of plethodontids are driven by temperature and moisture, and the spatial patterns of suitable microhabitats drive regional scale patterns. Incorporating multiple environmental gradients provides a more biologically relevant prediction of abundance patterns, which will help inform conservation and management strategies especially in the context of climate change.

Evaluation of Barrier Sprays for Controlling Mosquitoes in Eastern North Carolina: Can Land Cover and Spatial Analyses Improve Predictions of Efficacy?

Mosquitoes can be a nuisance and can transmit pathogens causing numerous diseases. Homeowners may hire private companies that use barrier sprays to alleviate mosquito-related issues, especially in areas where government funding for mosquito control programs is limited. Here, the spatial distribution of mosquitoes was evaluated in a suburban neighborhood during successive treatments with either Bifen Insecticide/Termiticide (active ingredient: bifenthrin) or Suspend Polyzone (active ingredient: deltamethrin) from May 17 to November 8, 2016. A total of 15,083 adult mosquitoes and 18,054 mosquito eggs were collected. Analysis of variance (P < 0.05) was used to analyze differences in abundance of key species between weeks, traps, and treatments. Weather trends were analyzed in relation to mosquito abundance using time-lagged weekly average temperatures and total rainfall. Kriging showed hot spots of mosquito abundance. The spatial pattern of abundance was different for oviposition and adults, and this was expected because of different types of traps used here. A land cover analysis was performed within the geographic information system (GIS) file to determine the extent to which land cover type could predict mosquito abundance. We show an uneven distribution of host-seeking mosquito abundance and that, in general, mosquitoes preferred areas that were lightly wooded or composed of small collections of trees or bushes, compared with larger densely wooded areas. Analyses of spatial distribution, land cover, and weather can be used to supplement an integrated mosquito management approach.

Confluence configuration of river networks controls spatial patterns in fish communities

Given the importance of spatial heterogeneity in altering dispersal, interspecific interactions, and population persistence, high rates of habitat homogenisation across the globe are a concern. In river ecosystems, confluences likely act as heterogeneity ‘hotspots’ by creating discontinuities in longitudinal processes and influences that are propagated both up and down stream networks. We predicted the layout of abiotic conditions around confluences would influence the presence and configuration of spatial heterogeneity, and strongly influence spatial patterns in fish abundance and evenness. Twelve replicate mainstem and tributary stream combinations in Canterbury, New Zealand, were electrofished to evaluate how the configuration of flow disturbance (i.e. flooding) characteristics around a confluence (i.e. stable mainstem and disturbed tributary versus disturbed mainstem and stable tributary) influenced fish communities. The configuration of abiotic conditions around confluences, and position of a sampled reach with respect to the confluence, significantly interacted to create configuration-specific patterns in fish abundance and evenness. Fish abundances were particularly high in disturbed tributaries juxtaposed with stable mainstems, suggesting certain confluence configurations are disproportionately ecologically important. Evenness scores differed significantly downstream of confluences, depending on configuration, with highest fish evenness in reaches downstream of confluences between a stable and a disturbed stream. These results reveal strongly context-dependent spatial patterns in communities and demonstrate the role of spatially transferred influence in river systems. Understanding importance of not just the presence of heterogeneity, but its configuration and context-dependence in the landscape will assist in identifying sites of ecological significance for management and conservation purposes.

Different environmental drivers of alien tree invasion affect different life-stages and operate at different spatial scales

Identifying the key factors driving invasion processes is crucial for designing and implementing appropriate management strategies. In fact, the importance of (model-based) prevention and early detection was highlighted in the recent European Union regulation on Invasive Alien Species. Models based on abundance estimates for different age/size classes would represent a significant improvement relative to the more usual models based only on species’ occurrence data. Here, we evaluate the relative contribution of different environmental drivers to the spatial patterns of abundance of several height classes (or life-stages) of invasive tree populations at the regional scale, using a data-driven hierarchical modelling approach. A framework for modelling life-stages to obtain spatial projections of their potential occurrence or abundance has not been formalized before.We used Acacia dealbata (Silver-wattle) as a test species in northwest of Portugal, a heavily invaded region, and applied a multimodel inference to test the importance of various environmental drivers in explaining the abundance patterns of five plant height classes in local landscape mosaics. The ensemble of height classes is considered here as a proxy for population dynamics, life-stages and age of adult trees. In this test with A. dealbata, we used detailed field data on population height structure and calibrated an independent model for each height class. We found evidence to support our hypothesis that the distribution of height classes is mostly influenced by distinct factors operating at different scales. The spatial projections which resulted from several height class models provide an overview of population structure and invasion dynamics considering various life-stages, that is widely used in biodiversity and invasion research.The approach proposed here provides a framework to guide forest management to deal more effectively with plant invasions. It allows to test the effects of key invasion factors (depending on the focal species and on data availability) and supports the spatial identification of suitable areas for invasive species’ occurrence while also accounting for the structural complexity of invasive species populations, thereby anticipating future invasion dynamics. The approach thus constitutes a step forward for establishing management actions at appropriate spatial scales and for focusing on earlier stages of invasion and their respective driving factors (regeneration niche), thereby enhancing the efficiency of control actions on major forest invaders.

Mapping Ice Algal Blooms in Southwest Greenland From Space

AbstractQuantifying the distribution and abundance of ice algae is fundamental for understanding the evolving processes of algal blooms in supraglacial environments, particularly over the Greenland ice sheet, given the role of algal impurities in modulating surface albedo and meltwater production. Field observations of ice algae in Greenland are very limited over space and time. Here we show for the first time the regional variability in algal abundance across the dark zone in southwest Greenland, derived from Sentinel‐3 images acquired during the summertime in 2016 and 2017. We demonstrate the capacity of Sentinel‐3 imagery to characterize the spatial pattern of algal abundance using the reflectance ratios between 709‐ and 673‐nm bands, highly consistent with field measurements. The estimated algal abundance reveals a significant linear growth pattern of algal population with time after the peak of dark ice presence, shown to be tightly linked to surface runoff and meltwater production.

Stored product insects at a rice mill: Temporal and spatial patterns and implications for pest management: Presentation

Monitoring is fundamental to integrated pest management programs since it provides feedback on effectiveness of prevention programs and helps with targeting interventions as needed and evaluating their effectiveness. Rice mills are spatially complex facilities that have a combination of rough rice storage bins, buildings where rice is milled and processed, and warehouses and bulk storage bins where finished product is held before shipment. Each of these structures can have its own suite of insect species, different levels of risk, as well as different suites of management tools available. At a large rice mill in Brazil, stored product insect activity was monitored using food bait traps placed around rough rice receiving areas and storage bins; inside building containing white rice mill, rice flour mill, and packaging; and inside building for processing parboiled rice. The facility was monitored from 2010 to 2018 with 100 traps. Major pest species recovered at the facility included Sitophilus oryzae, Sitophilus zeamais, Rhyzopertha dominica, Tribolium castaneum, Cryptolestes ferrugineus, Ahasverus advena, Oryzaephilus surinamensis, Typhaea stercorea, Anthicus floralis, and Nitidulidae species. Temporal and spatial patterns in abundance were evaluated for each of the major species and for major functional groups (primary feeders, secondary feeders, and fungal feeders). Monitoring data generated was used to guide pest management programs and also provided the information needed to develop management thresholds.

Assessment of spatial patterns in benthic macrofauna of the U.S. west coast continental shelf.

We assessed whether currently described marine biogeographic boundaries apply to shelf macrofauna and which environmental drivers were most associated with species differences among regions. Pacific coast of North America from the Strait of Juan de Fuca in Washington to the California-Mexico border. Van Veen grab samples were collected from soft sediment 28-138 m deep and sieved using 1 mm mesh. Spatial patterns of species richness, diversity, and abundance were examined in relation to latitude and environmental parameters (temperature, salinity, dissolved oxygen, sediment % fines, and total organic carbon). Analyses of latitudinal distribution patterns of individual species were combined with multivariate analyses of community composition to determine biogeographic and habitat boundaries for mid-depth continental shelf macrofauna. Species richness, diversity, and abundance significantly decreased with increasing latitude, primarily between 32 and 40° N. There were positive associations of richness, diversity (H'), and abundance with upwelling index, sediment % fines, and TOC (<2%). Temperature and DO also were significant for richness and H' but not abundance. Assessment of individual species ranges found major faunal transitions at latitudes 33-34°, 37°, 44°, and 46-47°. Major assemblage differences were found at 34.5°, and 42°. Within each latitudinal region, significantly different macrofauna communities were found in sediment with <5% fines. The biogeographic boundaries proposed under the Marine Ecoregions of the World schema are more closely aligned with shelf fauna distributions than those developed using west coast rocky intertidal communities. However, the proposed province boundary at Cape Mendocino is not apparent in the shelf macrofauna, and a transition appears to occur closer to the Oregon-California border. Further, the shelf macrofauna indicate the Channel Islands should be a separate subregion from mainland southern California Bight. Multivariate community analyses minimizing the impact of rare species appeared more useful in determining macrofaunal community biogeographic boundaries than analysis of individual species range endpoints, which are strongly influenced by uncommon species.

Spatial distribution and growth association of regeneration in gaps of Chinese pine (Pinus tabuliformis Carr.) plantation in northern China

Chinese pine is one of the major afforestation species in North China, and plantations of this species are of great significance for improving the ecological environment and for conserving soil and water. However, most of the Chinese pine plantations established by the government in the 1970s are mature or nearly mature. Therefore, how to successfully promote natural regeneration has become a major issue in plantation management. We established four types of gaps with different diameters in a plantation in northern China based on the average canopy height (H), i.e., L-I (0.75 H), L-II (1.00 H), L-III (1.25 H), and L-IV (1.50 H). Seven years after gap creation, each gap was divided into four aspects by vertical lines along the main direction of the gap center. Additionally, three sections were partitioned in each gap according to the mean crown radius of the border trees; these sections were the central area of the gap (section B), the inner edge of the gap (section C) and the outer edge of the gap (section D). The results showed that there were no differences in density among gap size classes and gap aspects, but a positive response was observed for regeneration growth. The maximum growth in L-III implied that this gap was the optimal size for promoting the establishment, survival and development of regenerated trees. The highest density and greatest growth occurred mostly along the gap edge. Spatial patterns of abundance were generally concurrent with patterns of regeneration stature (e.g., height) in all tested gaps. However, the spatial distributions of regeneration density and growth exhibited obvious differences in different gap size classes, which likely resulted from heterogeneity in the micro-environment within the gap and the differences in the regeneration responses to these variations. The mark correlation function indicated that spatial autocorrelation characteristics of regeneration growth within gaps and gap sections were mainly independent. Collectively, our findings suggested that the expansion of gaps with continuous monitoring will likely be necessary to promote further canopy recruitment. Additionally, regenerating trees exhibited different spatial distributions and could be more resilient to various interferences. Factors influencing the differences in spatial distribution need to be further studied in light of the relationship between variations in the micro-environment and regeneration responses after gap creation. Moreover, whether large-scale vegetation displacement and reorganization will result from clear cutting these plantations warrants further investigation.

Land use legacy for a tropical myco-heterotroph: how spatial patterns of abundance, reproductive effort and success vary

Land use legacy for a tropical myco-heterotroph: how spatial patterns of abundance, reproductive effort and success vary

Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil

ABSTRACT The Paranapanema River is a major tributary of the upper Paraná river basin. Eleven hydropower dams regulate its main course, but no study has investigated fish diversity in these impoundments at the basin-scale. The present study investigated spatial patterns of richness, composition, and abundance of native (non-migratory and migratory) and non-native fishes in the cascade of reservoirs along the Paranapanema River. The study is based on data collected from 34 independent studies conducted in nine reservoirs (47 samples). The compilation recorded 161 species, being 111 native (14 migratory) and 50 non-native. Total richness ranged between 56 and 112 species/reservoir, with a mean of 72 (49.9 non-migratory, 8.1 migratory and 14 non-native). The number of non-migratory species showed no spatial trend along the cascade system, but migratory and non-native richness increased toward downstream reaches. We also observed spatial variation in species composition along the cascade system, but some non-native fishes were widely distributed. Migratory fishes showed low relative abundance (usually &lt; 10%), while non-native species were common and more abundant, especially in reservoirs downstream. Our results revealed a high diversity of fishes in the cascade of impoundments, but indicated that migratory fishes are rare, while non-native species are common or dominant.

Spatial variability and abundance pattern of Indian squid off Maharashtra coast, India

An analysis was carried out on monthly spatial distribution and unusual congregation of Indian squid (Uroteuthis (Photololigo) duvaucelii) off Maharashtra coast. Decadal, annual and monthly squid landing data were taken from National Marine Living Resources Data Centre (NMLRDC) of ICAR-CMFRI. Onboard fisheries information were collected from multi-day trawlers operating from Mumbai and Ratnagiri. Ocean environment parameters coming from Copernicus Marine Service Information with 1/12 degree horizontal resolution and 50 vertical depth level and OSCAR (Ocean Surface Current Analysis Real-time) near-surface ocean current estimates was derived using quasi-linear and steady flow momentum equations on a 1/3 degree grid with a 5 day resolution. In last decade, contribution of squid to total marine fish landing of Maharashtra rose from 2% to 7.3%. The decadal landing shows two peaks in 2012 and 2017. Indian squid landing in 2017 shows two peak, one during August to October confined to 150 N to 170 N latitude in 15 to 60 m depth off south Maharashtra and second in summer, during March-April months widely scattered in north and south Maharashtra. The unusual abundance of Indian squid during mid-October to mid- November 2017 were attributed to rise in coastal surface and subsurface temperature. Catch per hour of trawl and SST shows strong positive correlation (0.79) during the same period.

Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa.

All over the world, pollinators are threatened by land‐use change involving degradation of seminatural habitats or conversion into agricultural land. Such disturbance often leads to lowered pollinator abundance and/or diversity, which might reduce crop yield in adjacent agricultural areas. For West Africa, changes in bee communities across disturbance gradients from savanna to agricultural land are mainly unknown. In this study, we monitored for the impact of human disturbance on bee communities in savanna and crop fields. We chose three savanna areas of varying disturbance intensity (low, medium, and high) in the South Sudanian zone of Burkina Faso, based on land‐use/land cover data via Landsat images, and selected nearby cotton and sesame fields. During 21 months covering two rainy and two dry seasons in 2014 and 2015, we captured bees using pan traps. Spatial and temporal patterns of bee species abundance, richness, evenness and community structure were assessed. In total, 35,469 bee specimens were caught on 12 savanna sites and 22 fields, comprising 97 species of 32 genera. Bee abundance was highest at intermediate disturbance in the rainy season. Species richness and evenness did not differ significantly. Bee communities at medium and highly disturbed savanna sites comprised only subsets of those at low disturbed sites. An across‐habitat spillover of bees (mostly abundant social bee species) from savanna into crop fields was observed during the rainy season when crops are mass‐flowering, whereas most savanna plants are not in bloom. Despite disturbance intensification, our findings suggest that wild bee communities can persist in anthropogenic landscapes and that some species even benefitted disproportionally. West African areas of crop production such as for cotton and sesame may serve as important food resources for bee species in times when resources in the savanna are scarce and receive at the same time considerable pollination service.

Do genetic diversity patterns of soil ammonia-oxidizing microorganisms (AOM) match the habitat types of the NATURA2000 scheme?

Despite the important role of soil ammonia-oxidizing microorganisms (AOM) in the biogeochemical cycle of nitrogen, a unified view of the factors driving their spatial pattern of abundance and genetic diversity in terrestrial ecosystems is still lacking. The objective of this study was to explore whether abundance and genetic diversity of AOM follow the existing diversity of habitat types of the NATURA2000. We evaluated the relative abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA), as well as their genetic diversity in pastoral landscapes of an eastern Mediterranean island. Focusing on six different NATURA2000 habitat types of Crete, the study of AOM was based on culture-independent techniques, while vegetation and soil data of each habitat type were also collected and incorporated in the analysis. Our results suggest that the relative abundances of soil AOB and AOA in the pastoral landscapes of Crete are related to a limited number of soil factors, while their genetic diversity patterns are mainly explained by the dominant woody plant families, and partially by the soil parameters, but do not match the habitat types of the NATURA2000 scheme. The variation of genetic diversity of soil AOM is not predicted from the habitat types of the NATURA2000 scheme. Thus, NATURA2000 habitat types cannot serve as a management scheme of soil AOM.

Seagrass macrofaunal abundance shows both multifractality and scale-invariant patchiness

Spatial patterns of abundance of the whole macrobenthic assemblage and of its 10 most numerous species were examined across hierarchically nested scales within a 0.85 ha area of intertidal seagrass in subtropical Moreton Bay, Queensland. Multifractality characterised the assemblage and all ten dominant species across those scales (c. 33, 130, 530 & 2115 m2), with patchiness of assemblage numbers and those of at least some dominants exhibiting scale-invariance. The system displayed several abundance peaks, 12% of stations accounting for 88% of total variance, with many individual dominants showing a series of non-overlapping 'hot-spots'. Scale invariance and multifractality occurred notwithstanding low levels of species interaction consequent on maintenance at very low density. This suggests that critical self-organisation cannot be responsible for such patterning. Contrary to received wisdom, coefficient β of Taylor's power-law cannot form an index of aggregation, although it does indicate direction of change in dispersion pattern with changing numbers.

Spatiotemporal patterns of phytoplankton composition and abundance in the Maryland Coastal Bays: The influence of freshwater discharge and anthropogenic activities

The spatial and temporal variations in phytoplankton abundance and community structure in the northern and southern parts of the Maryland Coastal Bays (MCBs) that differ in anthropogenic activities and hydrological characteristics were studied in 2012 and 2013 using photosynthetic pigments as biomarkers. Phytoplankton pigment biomass and diversity were generally higher in the northern bays that receive high nutrient input from St. Martin River, than in the southern bays where nutrient levels were comparatively low. Sites close to the mouths of tributaries in northern and southern bays had higher nutrient levels, which favored the development of dinoflagellates, and nano- and picophytoplankton, than sites closer to the inlets. The microplankton dominated the phytoplankton community in spring (>90%) and decreased in relative abundance into fall (<60%) whereas nanoplankton peaked in summer or fall. Picoplankton relative abundance increased from late spring (<10%, March 2012 & 2013) to summer (40%, July 2012 and August 2013) and was correlated positively with NH4+ and negatively with salinity. The observed spatial and seasonal patterns of phytoplankton relative abundance and diversity are likely due to changes in nutrient concentrations and ratios, driven by variations in freshwater discharge, and selective grazing of phytoplankton. Water quality management in the MCBs should continue to focus on reducing nutrient inputs into the bays.

Climate change likely to reduce orchid bee abundance even in climatic suitable sites.

Studies have tested whether model predictions based on species' occurrence can predict the spatial pattern of population abundance. The relationship between predicted environmental suitability and population abundance varies in shape, strength and predictive power. However, little attention has been paid to the congruence in predictions of different models fed with occurrence or abundance data, in particular when comparing metrics of climate change impact. Here, we used the ecological niche modeling fit with presence-absence and abundance data of orchid bees to predict the effect of climate change on species and assembly level distribution patterns. In addition, we assessed whether predictions of presence-absence models can be used as a proxy to abundance patterns. We obtained georeferenced abundance data of orchid bees (Hymenoptera: Apidae: Euglossina) in the Brazilian Atlantic Forest. Sampling method consisted in attracting male orchid bees to baits of at least five different aromatic compounds and collecting the individuals with entomological nets or bait traps. We limited abundance data to those obtained by similar standard sampling protocol to avoid bias in abundance estimation. We used boosted regression trees to model ecological niches and project them into six climate models and two Representative Concentration Pathways. We found that models based on species occurrences worked as a proxy for changes in population abundance when the output of the models were continuous; results were very different when outputs were discretized to binary predictions. We found an overall trend of diminishing abundance in the future, but a clear retention of climatically suitable sites too. Furthermore, geographic distance to gained climatic suitable areas can be very short, although it embraces great variation. Changes in species richness and turnover would be concentrated in western and southern Atlantic Forest. Our findings offer support to the ongoing debate of suitability-abundance models and can be used to support spatial conservation prioritization schemes and species triage in Atlantic Forest.

Spatial patterns in abundance, taxonomic composition and carbon biomass of nano- and microphytoplankton in Subarctic and Arctic Seas

In the summers of 2007 and 2008, we studied assemblages of nano- and microphytoplankton from the subsurface chlorophyll maximum (SCM) across five broad oceanographic domains in the seas surrounding northern North America. These domains are the eastern Subarctic North Pacific (ESNP), Bering and Chukchi Seas (BE-CH), Beaufort Sea and Canada Basin (BS-CB), Canadian Arctic Archipelago (CAA), and Baffin Bay and Labrador Sea (BB-LS). Average abundance and total carbon biomass (C) of phytoplankton (>2 µm) varied ∼10-fold and ∼20-fold, respectively, across the five domains. In the BE-CH, CAA and BB-LS, diatoms averaged 35–70% and dinoflagellates 11–45% of total phytoplankton C (>2 µm), whereas in the ESNP and BS-CB, unidentified flagellates/coccoids (2–8 µm) represented a greater proportion of total C (27% and 39% respectively) than in the other domains.In the BE-CH and BB-LS, phytoplankton C (>2 µm) was dominated by dinoflagellates of the genus Gymnodinium, centric diatoms including Thalassiosira spp. and Chaetoceros spp., unidentified flagellates/coccoids (2–8 µm), and cryptomonads. In contrast, diatoms such as Thalassiosira spp. and its resting spores dominated C in the CAA, with dinoflagellates being less significant than in the BE-CH and BB-LS. Unidentified flagellates/coccoids (2–8 µm), Gymnodinium spp., and cryptomonads dominated in the ESNP, and particularly in the BS-CB, where diatoms contributed only 18% of the very low levels of total phytoplankton C (>2 µm).Phytoplankton C (>2 µm) to chlorophyll a ratios (phyto C:chl a) averaged only 31 g C g chl a−1 in the oligotrophic BS-CB domain, and 51–150 g C g chl a−1 in the other domains, whereas ratios of biogenic silica to phytoplankton C (>2 µm) (bSi:phyto C) were lowest in the eastern domains. Estimates of phytoplankton C were highly sensitive to the choice of C to cell volume equations (C:vol) adopted in the calculations, particularly in diatom-rich areas.This study highlights how diatoms and dinoflagellates are the main drivers of large-scale variations in C biomass for phytoplankton (> 2 µm), whereas unidentified flagellates/coccoids (2–8 µm) make a significant contribution to C biomass in oligotrophic domains, such as BS-CB, where diatoms and dinoflagellates are less abundant. Reduced surface water density (σT) was associated with deeper SCM layers, and with decreased C biomass of unidentified flagellates/coccoids (2–8 µm). These observations confirm recent studies highlighting the role of surface water stratification caused by melting sea ice in shaping nano- and microphytoplankton assemblages.

The longer the better: the effect of substrate on sessile biota in Arctic kelp forests

Kelps are ecosystem engineers and thus enhance biodiversity and subsidize food webs in nearshore areas. Numerous studies describing diversity and abundance of biota associated with kelp have focused on sub-tropical and temperate waters while kelp forests at high latitudes, where kelp is predicted to expand in distribution, remain mostly unexplored. Kelp forests contribute significantly to regional biodiversity, and associated fauna and the kelp themselves play ecologically important roles as habitat and feeding areas. Here, we report patterns in diversity, abundance and seasonal dynamics of fouling organisms associated with different regions of Saccharina latissima and nearby substrates (including stones of the barren ground). The study was conducted in Kongsfjorden, a high Arctic fjord on the west coast of Spitsbergen; and samples were taken five times between September 2013 and January 2015. Trends in species richness of epifauna were similar for stones and holdfasts: higher in winter (due the presence of rare species), and lower in spring and autumn. Species richness and abundance demonstrated a clear tendency to increase in accordance with substrate stability. Stones housed the most diverse biota compared to living substrates. Holdfasts demonstrated similar patterns in species composition and abundance as stones due their close spatial arrangement and presence of demersal larvae in most of fouling organisms. Similarly, assemblages on blades in prostrate kelp forests are influenced by the species inhabiting stones of the barren ground. Both biotic and abiotic factors, including habitat stability and proximity to source populations, contribute to these spatial and temporal patterns in faunal abundance and diversity.

Spatio-temporal arrangement of Chamaerops humilis inflorescences and occupancy patterns by its nursery pollinator, Derelomus chamaeropsis.

Nursery pollination is a highly specialized interaction in which pollinators breed inside plant reproductive structures. Pollinator occupancy of host plants often depends on plant location, flowering synchrony and sex. The nursery pollination system between the dioecious dwarf palm Chamaerops humilis (Arecaceae) and the host-specific palm flower weevil Derelomus chamaeropsis was investigated. For the first time, sex, flowering synchrony and spatial distribution of plants was related to the occupancy probability and the abundance of D. chamaeropsis larvae, important traits influencing both pollinator and plant fitness. During the flowering season, all inflorescences in anthesis were counted every 12 d and a flowering synchrony index was calculated taking into account all possible correlations with generalized linear mixed models. To analyse the spatial structure of plants, larva occupancy and abundance, different techniques of spatial point pattern analysis were used. In total, 5986 larvae in 1063 C. humilis inflorescences were recorded over three consecutive seasons. Male inflorescences showed a higher presence and abundance of weevil larvae than females, but interestingly approx. 30 % of the females held larvae. Also, larvae occurred mainly in highly synchronous plants with a low number of inflorescences, perhaps because those plants did not lead to a resource dilution effect. There was no evidence of spatial patterns in larva occupancy or abundance at any spatial scale, suggesting high dispersal ability of adult weevil. The results in a nursery-pollinated dioecious palm demonstrate that plant sex, flowering display and flowering synchrony act as additive forces influencing the presence and abundance of the specialized pollinator larvae. Contradicting previous results, clear evidence that female dwarf palms also provide rewarding oviposition sites was found, and thus the plant 'pays' for the pollination services. The findings highlight that plant local aggregation is not always the main determinant of pollinator attraction, whereas flower traits and phenology could be critical in specialized plant-pollinator interactions.