Phytoplankton biomass from continuous plankton recorder data: an assessment of the phytoplankton colour index

A 15 month time-series of simultaneous fluorometric measurementsof chlorophyll a, and phytoplankton cell abundance and a phytoplanktoncolour index (PCI) from continuous plankton recorder (CPR) samplesare compared for the Iberian margin, western Europe. The relationshipsbetween fluorometrically determined chlorophyll, cell abundanceand PCI are all significant, with PCI showing a better relationshipto chlorophyll than cell abundance. This supports previous researchwhich suggests that the PCI is a useful index of phytoplanktonstanding stock and, furthermore, may be a measure of cells thatare not preserved or counted in the routine microscopic processingof CPR samples. The relationship between PCI and chlorophyllappears to vary seasonally, although more extensive data areneeded to quantify this variability. The study also comparesthe PCI and fluorometer data with chlorophyll values obtainedfrom satellite imagery (SeaWiFS) for the Iberian margin. Significantcorrelations exist during the 15 month time-series between thesethree estimates of phytoplankton concentration. This resultdemonstrates that the ~50 year time-series of PCI for the NorthAtlantic can provide valuable information on changes in phytoplanktonstanding stock.     

Genetic monitoring of open ocean biodiversity: An evaluation of DNA metabarcoding for processing continuous plankton recorder samples

DNA metabarcoding is an efficient method for measuring biodiversity, but the process of initiating long‐term DNA‐based monitoring programmes, or integrating with conventional programs, is only starting. In marine ecosystems, plankton surveys using the continuous plankton recorder (CPR) have characterized biodiversity along transects covering millions of kilometres with time‐series spanning decades. We investigated the potential for use of metabarcoding in CPR surveys. Samples (n = 53) were collected in two Southern Ocean transects and metazoans identified using standard microscopic methods and by high‐throughput sequencing of a cytochrome c oxidase subunit I marker. DNA increased the number of metazoan species identified and provided high‐resolution taxonomy of groups problematic in conventional surveys (e.g., larval echinoderms and hydrozoans). Metabarcoding also generally produced more detections than microscopy, but this sensitivity may make cross‐contamination during sampling a problem. In some samples, the prevalence of DNA from large plankton such as krill masked the presence of smaller species. We investigated adding a fixed amount of exogenous DNA to samples as an internal control to allow determination of relative plankton biomass. Overall, the metabarcoding data represent a substantial shift in perspective, making direct integration into current long‐term time‐series challenging. We discuss a number of hurdles that exist for progressing DNA metabarcoding from the current snapshot studies to the requirements of a long‐term monitoring programme. Given the power and continually increasing efficiency of metabarcoding, it is almost certain this approach will play an important role in future plankton monitoring.     

An investigation of the spatial pattern of zooplankton using the Longhurst-Hardy plankton recorder

The spatial pattern of planktonic ostracods and copepods has been studied using Longhurst-Hardy plankton recorder tows at a depth of 550 m in the North Atlantic. The majority of the more abundant animals were found to be overdispersed. A three parameter contagious distribution described by Skellam was used to fit the observed spatial patterns. The main conclusions are that the patch size did not vary greatly between species and that denser populations were the result of an increase in centres of aggregations rather than the size of the patch or number of animals per patch. Although some species did show broad changes in abundance correlated with temperature, this could not explain the local abundance changes associated with the patches. Other possible causes of the patchiness are discussed.     

Influence of environmental variability on breeding effort in a long-lived seabird, the yellow-nosed albatross

The provisioning parameters, breeding success, adult mass, andsurvival of yellow-nosed albatrosses were studied over 7 successiveyears at Amsterdam Island, southern Indian Ocean. We examinedthe ability of this long-lived seabird to adjust its breedingeffort under different environmental conditions and the fitnessconsequences in terms of survival and quality of offspring produced. Provisioning rate and adult mass varied extensivelybetween years, and the lowest and highest values were associatedwith sea surface temperature anomalies. When waters aroundthe island were colder, adults were in good condition and broughtlarge meals at short intervals, whereas warmer waters resultedin lower provisioning rates, lower adult mass, and lighter chicksat fledging. Adult survival and fledging success were not affectedby sea surface temperature anomalies. Yellow-nosed albatrossesappear to be unable to adjust their breeding effort every season,and their differential breeding investment probably primarilyreflects different levels of food availability. Yellow-nosedalbatrosses are able to regulate their provisioning behavior according to the nutritional status of their chick only whenconditions are favorable. Birds appear to invest primarilyin their own future maintenance rather than in provisioning.They have a wide safety margin in body mass that limits mortalityrisks during good years as well as during poor years. However,during unfavorable seasons adults continue to provision chicksthat have a poor prospect of survival to breeding, withoutadditional survival costs for the parents. Favorable seasonstherefore have a high value in terms of fitness because ofthe high quality of the chick produced. We suggest that understandinghow long-lived animals optimize their provisioning behaviorand lifetime reproduction can only be achieved through studiesencompassing several contrasted seasons.     

Yolk carotenoids and stable isotopes reveal links among environment, foraging behavior and seabird breeding success

Nutrients that are limited in availability, such as carotenoids, are potentially involved in trade-offs between homeostasis and reproduction. Despite their importance, factors that affect the capacity of female birds to meet their carotenoid requirements are poorly understood. We used δ¹⁵N stable isotope analysis to relate foraging behavior to yolk carotenoid deposition in two seabirds, Cassin’s auklet (Ptychoramphus aleuticus) and rhinoceros auklet (Cerorhinca monocerata), during each of five years. As expected from their narrower trophic range, Cassin’s auklets produced yolks with fewer carotenoid types than did rhinoceros auklets (one vs. three). Cassin’s auklets also fed on a lower trophic level diet richer in carotenoids, yet had lower total yolk carotenoid levels, which suggests a role for species-specific adaptations for carotenoid uptake and utilization. Within both species, lower trophic-level feeding was linked to higher yolk carotenoid levels, but through different mechanisms. In Cassin’s auklets, it was due to a population-wide response to environmental variation: in warm-water years, all females fed at a low trophic level and produced carotenoid-rich yolks. In rhinoceros auklets, it was due to individual differences similarly expressed in all years: females fed across a wide trophic range, and those that fed at a low trophic level produced carotenoid-rich yolks. Rhinoceros auklets bred more successfully in years when their yolks were rich in carotenoids, probably due to a correlated response to stronger marine primary production. Our results are novel because they link avian yolk carotenoid deposition to behavioral and environmental variations.     

Disentangling environmental correlates of vascular plant biodiversity in a Mediterranean hotspot

We determined the environmental correlates of vascular plant biodiversity in the Baetic‐Rifan region, a plant biodiversity hotspot in the western Mediterranean. A catalog of the whole flora of Andalusia and northern Morocco, the region that includes most of the Baetic‐Rifan complex, was compiled using recent comprehensive floristic catalogs. Hierarchical cluster analysis (HCA) and detrended correspondence analysis (DCA) of the different ecoregions of Andalusia and northern Morocco were conducted to determine their floristic affinities. Diversity patterns were studied further by focusing on regional endemic taxa. Endemic and nonendemic alpha diversities were regressed to several environmental variables. Finally, semi‐partial regressions on distance matrices were conducted to extract the respective contributions of climatic, altitudinal, lithological, and geographical distance matrices to beta diversity in endemic and nonendemic taxa. We found that West Rifan plant assemblages had more similarities with Andalusian ecoregions than with other nearby northern Morocco ecoregions. The endemic alpha diversity was explained relatively well by the environmental variables related to summer drought and extreme temperature values. Of all the variables, geographical distance contributed by far the most to spatial turnover in species diversity in the Baetic‐Rifan hotspot. In the Baetic range, climate was the most significant driver of nonendemic species beta diversity, while lithology and climate were the main drivers of endemic beta diversity. Despite the fact that Andalusia and northern Morocco are presently separated by the Atlantic Ocean and the Mediterranean Sea, the Baetic and Rifan mountain ranges have many floristic similarities – especially in their western ranges – due to past migration of species across the Strait of Gibraltar. Climatic variables could be shaping the spatial distribution of endemic species richness throughout the Baetic‐Rifan hotspot. Determinants of spatial turnover in biodiversity in the Baetic‐Rifan hotspot vary in importance between endemic and nonendemic species.     

Recruitment to a seabird population depends on environmental factors and on population size

1. A novel capture-mark-recapture (CMR) method was used to build a multistate model of recruitment by young birds to a breeding population of common guillemots Uria aalge on the Isle of May, Scotland. Recruitment of a total of 2757 individually marked guillemots over 17 years was modelled as a process where individuals had to move from an unobservable state at sea, through a nonbreeding state present in the colony, to the breeding state. The probabilities of individuals returning to the colony in a given year, at age 2 and 3-4 years, were positively correlated with an environmental covariate, the winter North Atlantic Oscillation index (WNAO) in the previous years. 2. For 2 year olds, there was a negative relationship with breeding population size, suggesting that density dependence operated in this colony through limitation of food or some other resource. 3. Survival over the first 2 years of life varied with cohort, but was unrelated to the WNAO. Mean survival over this 2-year period was high at 0.576 (95% CI: 0.444; 0.708). 4. This high survival, combined with a low 'local' survival after age 5 years of 0.695 (0-654; 0.733) and observations of Isle of May chicks at other colonies, suggests that most surviving chicks return to the natal colony before deciding whether to recruit there or move elsewhere.     

Power law relationships among hierarchical taxonomic categories in algae reveal a new paradox of the plankton

Aim In this continental‐scale study, the biodiversity of benthic and planktonic algal communities was explored. A recent analysis of extinct and extant tree communities by Enquist et al. (2002) showed that richness of higher taxa was a power function of species richness, invariant across temporal and spatial scales. Here we examined whether the relationships between algal richness at hierarchical taxonomic levels conform to power laws as seen for trees, and if these relationships differ between benthic and planktonic habitats. Location Streams from more than 50 major watersheds in the United States. Method A total of 3698 samples were collected from 1277 locations by the National Water‐Quality Assessment Program. Three types of stream habitat were sampled: richest targeted habitats, depositional targeted habitats, and phytoplankton. The relationships between taxonomic richness at the species level vs. all higher categories from genus to phylum across the three habitats were examined by ordinary least squares (OLS) regressions after ln‐transformation of all variables. The slopes, b, of these regressions represent the exponents of the power functions that scaled the richness of higher taxonomic levels (T) to species richness (S) in the form: T∝S^b. Results Algal richness at hierarchical taxonomic categories (genus to phylum) is a power function of species richness. The scaling exponent of this function, which captures the diversification of higher taxa, i.e. the rate of increase of their richness with the increase of species richness, is significantly different across environments. Main conclusions The differential algal diversification in the three studied habitats emphasizes the fundamental role of the environment in structuring the communities of simple organisms such as algae. The finding that the diversification of higher taxa is greater in the seemingly homogeneous planktonic environment, when compared to benthic habitats, encompassing an array of ecological niches, poses a new paradox of the plankton.     

Effective molecular examination of eukaryotic plankton species diversity in environmental seawater using environmental PCR,PCR-RFLP,and sequencing

Phytoplankton are primary producers and can be important indicators of environmental change. To monitor the plankton species composition of environmental seawater samples, we developed a molecular method composed of colony polymerase chain reaction (PCR), polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP), and sequencing. A clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by environmental PCR using a newly designed primer set and clones were directly amplified by colony PCR. To select unique putative clones, we choose a PCR-RFLP method that employed two restriction enzymes (MseI and Tsp509I). After the PCR-RFLP pattern was evaluated, selected clones were sequenced and analyzed. In this study, we revealed the hidden biodiversity in environmental seawater containing a wide range of taxonomic groups in the Alveolata (Ciliphora and Dinophyceae), Euglenozoa, Stramenopiles (Bacillariophyta), and Viridiplantae (Chlorophyta) without the need to conduct extensive colony isolation techniques. Moreover, we found species of fungi and Metazoa (Arthropoda, Annelida, and Mollusca). Therefore, this improved molecular method can be used to generate a robust database describing the species diversity of environmental samples and provide useful information regarding the dynamics of the eukaryotic plankton community structure.     

Genetic data reveal wintering ground affiliation of humpback whales from the Mexican Central Pacific

Two groups of humpback whales inhabit the waters off the Pacific coast of Mexico the coastal wintering aggregation in the north (MX), and the southern Mexico/Central America wintering aggregation (S-MX/CEA) in the south. However, along the coast of the Mexican Central Pacific (MCP), the population affiliation of humpback whales is uncertain. Some studies have concluded that the MCP whales are part of S-MX/CEA, while others have suggested that the MCP may represent an overlap zone between the two wintering aggregations. In this study, data from 354 biopsy samples were collected over a 12-year period, to provide insight from genetic information into the affiliation of MCP whales to and the boundaries between the wintering aggregations. Using mitochondrial control region sequences, we found that the majority (73%) of MCP whales are part of MX, but that the boundary between the two wintering aggregations may shift latitudinally depending on environmental conditions. The high haplotypic (h ± SD = 0.859 ± 0.0138) and nucleotide diversity (π ± SD = 0.0145 ± 0.0075) of the MCP whales are also consistent with our sample, including animals from both wintering aggregations. More research is needed to better describe the ranges of the MX and S-MX/CEA wintering aggregations to ensure their successful conservation and management.     

Modeling territory attendance and preening behavior in a seabird colony as functions of environmental conditions

In previous studies we developed a general compartmental methodology for modeling animal behavior and applied the methodology to marine birds and mammals. In this study we used the methodology to construct a system of two differential equations to model the dynamics of territory attendance and preening in a gull colony on Protection Island, Strait of Juan de Fuca, Washington. We found that colony occupancy was driven primarily by abiotic environmental conditions, including tide height, time of day, solar elevation, and wind speed over open water. For birds in the colony, preening behavior was driven to some extent by abiotic environmental conditions (including time of day, solar elevation, humidity, and wind speed on the colony), but apparently was driven primarily by local and/or biotic effects not included in the model. In terms of R ² values, the model explained 65% and 37% of the variability in colony occupancy and preening data, respectively, as a function of these six abiotic environmental factors.     

Genetic and environmental determinants of osteoporosis

Osteoporosis is a common, complex disease that is influenced by genetic and environmental factors. Although molecular genetic studies have identified several potential regions of linkage, underlying susceptibility gene(s) are largely unknown. Genetic susceptibility to osteoporosis may be both context dependent and developmentally regulated, and epigenetic mechanisms are the likely link between gene and environment. In this paper we will review the status of genetic research into osteoporosis, and present the evidence for gene-environment interaction in its pathogenesis. Finally, the current challenges and future directions of research will be briefly discussed.     

Exploring stream communities in a tropical biodiversity hotspot: biodiversity,regional occupancy,niche characteristics and environmental correlates

Exploring and describing biodiversity and the mechanisms structuring it is fundamental to advancing ecology. This is particularly pertinent in understudied biogeographical regions, such as the Afrotropics, that are characterised by strong seasonal climatic shifts. We investigated the characteristics of stream biodiversity in the Niger Delta region of Nigeria, a tropical biodiversity hotspot, by examining patterns in 20 stream invertebrate communities across both the wet and dry seasons. For this, we took a multi-faceted approach accounting for the three levels of biodiversity (α, β and γ), including partitioning the nestedness and turnover components of β diversity, regional occupancy-abundance patterns, niche characteristics, and the environmental drivers of community structure. α diversity was low in these streams, with strong turnover between sites leading to high β diversity contributing to regional biodiversity, but there was little variation in communities between seasons. The proportion of sites occupied by taxa declined with increasing niche position, and decreasing niche breadth. Occupancy was predicted well by a combination of these two factors (niche position and breadth), but not mean local abundance, as the abundance-occupancy link was an upper-limit unimodal relationship. On average, community structure was linked more strongly to environmental variables in the wet season. Our findings demonstrate the clear role of spatial, but not temporal, turnover in assemblages, which likely reflects the environmental heterogeneity of this region. This is further supported by the fact that regional occupancy was mostly related to niche characteristics, particularly niche position. We emphasise the importance of continued basic and applied ecological work in this important biogeographic region to enable better protection of its biodiversity.     

Video plankton recorder reveals high abundances of colonial Radiolaria in surface waters of the central North Pacific

Colonial spumellarian Radiolaria are heterotrophic protiststhat form large (up to several meters in length), gelatinousstructures in the surface waters of all tropical and subtropicaloceanic ecosystems. These species are morphologically and trophicallycomplex and some, but not all, produce silica skeletal structuresof considerable paleontological significance. Skeletonless speciesof Radiolaria are poorly sampled by plankton nets, which canseverely damage these delicate organisms. Therefore, abundancesof colonial Radiolaria typically have been underestimated inquantitative studies of zooplankton abundance and biomass. Herewe document the abundances of colonial Radiolaria in the centralNorth Pacific based on analysis of video images from a miniaturizedvideo plankton recorder. We observed abundances of radiolariancells in colonies that exceeded previous reports of total Radiolariaby more than ten-fold, and counts of skeleton-bearing Radiolariaby more than two to three orders of magnitude. Biomass (carbon)within these colonies was similar to or greater than the totalradiolarian biomass (i.e. including all solitary species) previouslyreported for the Pacific. Symbiont productivity within colonialRadiolaria was estimated to constitute a modest but significantfraction of total primary productivity (up to     

Modeling territory attendance and preening behavior in a seabird colony as functions of environmental conditions

In previous studies we developed a general compartmental methodology for modeling animal behavior and applied the methodology to marine birds and mammals. In this study we used the methodology to construct a system of two differential equations to model the dynamics of territory attendance and preening in a gull colony on Protection Island, Strait of Juan de Fuca, Washington. We found that colony occupancy was driven primarily by abiotic environmental conditions, including tide height, time of day, solar elevation, and wind speed over open water. For birds in the colony, preening behavior was driven to some extent by abiotic environmental conditions (including time of day, solar elevation, humidity, and wind speed on the colony), but apparently was driven primarily by local and/or biotic effects not included in the model. In terms of R(2) values, the model explained 65% and 37% of the variability in colony occupancy and preening data, respectively, as a function of these six abiotic environmental factors.