Ocean Climate Conditions Research Articles

Ammonia and greenhouse gas emissions from an enriched cage laying hen facility

Ammonia, methane, nitrous oxide and carbon dioxide emissions were measured during a complete production cycle in an enriched cage laying hen facility under Oceanic climate conditions. Continuous monitoring of gas concentration, ventilation rate and environmental parameters were conducted from April 2012 to September 2013. The seasonal and diurnal pattern of gas emissions was analysed. Seasonality effect was found for NH 3 emission, showing an average emission of 144.9 mg d −1 hen −1 and 90.3 mg d −1 hen −1 in summer and winter, respectively. On the contrary, diurnal pattern of NH 3 emission did not differ between these seasons. For CO 2 , mean emission values did not show seasonality, although the diurnal pattern differed between winter and summer. Results obtained for CH 4 and N 2 O emissions did not provide sufficient evidence to determine either seasonality or diurnal effect on these gases. An NH 3 emission factor of 7% of total N in manure was defined for this system. These losses increased at higher ventilation rates and lower belt cleaning frequencies. Thus, NH 3 mitigation strategies at housing level should consider both parameters. Further studies would be necessary to determine how these factors regulate NH 3 emission at laying hen houses.

Humpback whale diets respond to variance in ocean climate and ecosystem conditions in the California Current.

Large, migratory predators are often cited as sentinel species for ecosystem processes and climate-related changes, but their utility as indicators is dependent upon an understanding of their response to environmental variability. Documentation of the links between climate variability, ecosystem change and predator dynamics is absent for most top predators. Identifying species that may be useful indicators and elucidating these mechanistic links provides insight into current ecological dynamics and may inform predictions of future ecosystem responses to climatic change. We examine humpback whale response to environmental variability through stable isotope analysis of diet over a dynamic 20-year period (1993-2012) in the California Current System (CCS). Humpback whale diets captured two major shifts in oceanographic and ecological conditions in the CCS. Isotopic signatures reflect a diet dominated by krill during periods characterized by positive phases of the North Pacific Gyre Oscillation (NPGO), cool sea surface temperature (SST), strong upwelling and high krill biomass. In contrast, humpback whale diets are dominated by schooling fish when the NPGO is negative, SST is warmer, seasonal upwelling is delayed and anchovy and sardine populations display increased biomass and range expansion. These findings demonstrate that humpback whales trophically respond to ecosystem shifts, and as a result, their foraging behavior is a synoptic indicator of oceanographic and ecological conditions across the CCS. Multi-decadal examination of these sentinel species thus provides insight into biological consequences of interannual climate fluctuations, fundamental to advancing ecosystem predictions related to global climate change.

Anchovy population and ocean-climatic fluctuations in the Humboldt Current System during the last 700 years and their implications

A marine sedimentary record collected from 87m water depth in a coastal environment of the Humboldt Current System (Mejillones Bay, 23° S, northern Chile) was used to reconstruct the past 700years of ocean-climatic conditions and to study the influence of any changes on anchovy population dynamics. We analyzed quartz, organic carbon, total nitrogen, alkenones and fish scales. Four stratigraphic units in the sediment column correspond with fluctuations in these and other proxies. Low Scale Deposition Rate (SDR) values from 1330 to 1420 suggest a low abundance of anchovy in this coastal environment. Three subsequent cycles of ca. 170years each showed an increase and decrease of anchovy populations, which is in agreement with changes in the wind regime, sea surface temperature and primary productivity.Since ca. 1840, marked fluctuations of SDR have been observed, probably as a consequence of the onset of a different oceanographic regime characterized by intensified southern winds and upwelling, colder surface waters, higher primary productivity, and enhanced “La Niña like” interdecadal variability. An increase of the anchovy population was observed until halfway through the 20th century, followed by a decrease, even though water temperature decreased and primary productivity increased. This situation is likely the consequence of the increased fishery activity that developed in this zone during the last 60years. After analyzing the results obtained for anchovy SDR, we can determine that there is a relation between the abundance of this species and phases of the Pacific Decadal Oscillation (PDO), in which an increase in the SDR coincides with a PDO cold phase, while a decline coincides with a warm phase.Fast Fourier transformation analysis applied to the time series obtained from the Mejillones sediment core and to the North Atlantic Oscillation (NAO), the PDO, and the solar irradiance index time series shows three different decadal cycles (80–100years, 61–75years and 45–48years approximately). Furthermore, the results of this study suggest that both the PDO and the NAO and the biogeochemical markers of Mejillones exhibit periodicities that fall within the 80 to 100year Gleissberg solar cycle, indicating that global solar radiation plays a key role in the local ocean-climatic processes and confirming teleconnection linkages between widely separated regions.

Effects of flow scarcity on leaf-litter processing under oceanic climate conditions in calcareous streams

Although temporary streams represent a high proportion of the total number and length of running waters, historically the study of intermittent streams has received less attention than that of perennial ones. The goal of the present study was to assess the effects of flow cessation on litter decomposition in calcareous streams under oceanic climate conditions. For this, leaf litter of alder was incubated in four streams (S1, S2, S3 and S4) with different flow regimes (S3 and S4 with zero-flow periods) from northern Spain. To distinguish the relative importance and contribution of decomposers and detritivores, fine- and coarse-mesh litter bags were used. We determined processing rates, leaf-C, -N and -P concentrations, invertebrate colonization in coarse bags and benthic invertebrates. Decomposition rates in fine bags were similar among streams. In coarse bags, only one of the intermittent streams, S4, showed a lower rate than that in the other ones as a consequence of lower invertebrate colonization. The material incubated in fine bags presented higher leaf-N and -P concentrations than those in the coarse ones, except in S4, pointing out that the decomposition in this stream was driven mainly by microorganisms. Benthic macroinvertebrate and shredder density and biomass were lower in intermittent streams than those in perennial ones. However, the bags in S3 presented a greater amount of total macroinvertebrates and shredders comparing with the benthos. The most suitable explanation is that the fauna find a food substrate in bags less affected by calcite precipitation, which is common in the streambed at this site. Decomposition rate in coarse bags was positively related to associated shredder biomass. Thus, droughts in streams under oceanic climate conditions affect mainly the macroinvertebrate detritivore activity, although macroinvertebrates may show distinct behavior imposed by the physicochemical properties of water, mainly travertine precipitation, which can override the flow intermittence effects.

When does higher spatial resolution rainfall information improve streamflow simulation? An evaluation using 3620 flood events

Abstract. Precipitation is the key factor controlling the high-frequency hydrological response in catchments, and streamflow simulation is thus dependent on the way rainfall is represented in a hydrological model. A characteristic that distinguishes distributed from lumped models is the ability to explicitly represent the spatial variability of precipitation. Although the literature on this topic is abundant, the results are contrasting and sometimes contradictory. This paper investigates the impact of spatial rainfall on runoff generation to better understand the conditions where higher-resolution rainfall information improves streamflow simulations. In this study, we used the rainfall reanalysis developed by Météo-France over the whole country of France at 1 km and 1 h resolution over a 10 yr period. A hydrological model was applied in the lumped mode (a single spatial unit) and in the semidistributed mode using three unit sizes of subcatchments. The model was evaluated against observed streamflow data using split-sample tests on a large set of French catchments (181) representing a variety of sizes and climate conditions. The results were analyzed by catchment classes and types of rainfall events based on the spatial variability of precipitation. The evaluation clearly showed different behaviors. The lumped model performed as well as the semidistributed model in western France, where catchments are under oceanic climate conditions with quite spatially uniform precipitation fields. By contrast, higher resolution in precipitation inputs significantly improved the simulated streamflow dynamics and accuracy in southern France (Cévennes and Mediterranean regions) for catchments in which precipitation fields were identified to be highly variable in space. In all regions, natural variability allows for contradictory examples to be found, showing that analyzing a large number of events over varied catchments is warranted.

Changes in Atlantic water properties: an important factor in the European Arctic marine climate

Abstract Walczowski, W., Piechura, J., Goszczko, I., and Wieczorek, P. 2012. Changes in Atlantic water properties: an important factor in the European Arctic marine climate. – ICES Journal of Marine Science, 69: 864–869. The advection of warm Atlantic water (AW) through the Nordic Seas and its transformation (cooling and freshening) is one of the most important climatological processes in the region. Time-series of hydrographic observations in the northern Nordic Seas and the Fram Strait region are presented and analysed. Significant variability in the properties of AW has been observed in recent years. A 15-year time-series of summer observations indicate positive trends in salinity and temperature and two 5–6-year cycles. The northward advance of AW in 2006 was an unprecedented event. The position of the warm-water tongue shifted more than 350 km to the north, and temperatures in the West Spitsbergen Current reached the highest values ever recorded. These changes in AW temperature, heat content, and northward transport had a strong influence on the oceanic climate and sea-ice conditions north of Svalbard. These oceanic signals led to environmental changes that confirm the primary role of the ocean in shaping the climate of the region.

Climate shifts the interaction web of a marine plankton community

AbstractClimatic effects in the ocean at the community level are poorly described, yet accurate predictions about ecosystem responses to changing environmental conditions rely on understanding biotic responses in a food‐web context to support knowledge about direct biotic responses to the physical environment. Here we conduct time‐series analyses with multivariate autoregressive (MAR) models of marine zooplankton abundance in the Northern California Current from 1996 to 2009 to determine the influence of climate variables on zooplankton community interactions. Autoregressive models showed different community interactions during warm vs. cool ocean climate conditions. Negative ecological interactions among zooplankton groups characterized the major warm phase during the time series, whereas during the major cool phase, ocean transport largely structured zooplankton communities. Local environmental conditions (sea temperature) and large‐scale climate indices (El Niño/Southern Oscillation) were associated with changes in zooplankton abundance across the full time series. Secondary environmental correlates of zooplankton abundance varied with ocean climate phase, with most support during the warm phase for upwelling as a covariate, and most support during the cool phase for salinity. Through simultaneous quantitation of community interactions and environmental covariates, we show that marine zooplankton community structure varies with climate, suggesting that predictions about ecosystem responses to future climate scenarios in the Northern California Current should include potential changes to the base of the pelagic food.

Effect of small reservoirs on leaf litter decomposition in Mediterranean headwater streams

Leaf litter decomposition is a crucial process providing matter and energy to communities inhabiting headwater streams. This process could be affected by many man-made landscape transformations and its response can vary depending on the climate setting. In this study, we test the hypothesis that the presence of small headwater reservoirs decreases litter decomposition downstream, as reported for temperate Oceanic climatic regions, and that this effect is more accentuated in the Mediterranean. The effect of small dams on the decomposition of alder (Alnus glutinosa) leaves was studied in four headwater streams in Catalonia (NE Spain). The presence of a dam affected litter decomposition rates in three of the four streams studied, and this depended on reservoir typology. In those with seasonal surface release, decomposition rates were slower downstream from the dams, but in the case of a continuous hypolimnetic release, it was faster, with higher DIN and temperature and abundance of shredders. Alder litter decomposition rates were twice those reported for Oceanic climatic conditions. In Mediterranean headwaters, the effect of small dams will even be more evident at an annual scale due to the diminished flow rates in summer and this effect will be more pronounced than in the more Oceanic.

Incidence of ‘Candidatus Liberibacter europaeus’ and phytoplasmas in Cacopsylla species (Hemiptera: Psyllidae) and their host/shelter plants

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium ‘Candidatus Liberibacter europaeus’ was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of ‘Ca. Phytoplasma pyri’. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that ‘Ca. Liberibacter europaeus’ is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with ‘Ca. Phytoplasma’ spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. ‘Ca. Liberibacter europaeus’ was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of ‘Ca. Liberibacter europaeus’ in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them.

Energetics of swimming to shore in the puerulus stage of a spiny lobster: Can a postlarval lobster afford the cost of crossing the continental shelf?

Nonfeeding postlarval pueruli of spiny lobsters migrate tens of kilometers across the continental shelf to settle in coastal waters. A model that analyzes hydrodynamic forces during swimming in the puerulus of Jasus edwardsii is described. The model calculates the speed at which forward propulsion balances drag. Calculated speeds agree with observed puerulus behavior. The computed mechanical work is converted to metabolic energy consumption using an assumed efficiency. Values concur with reported estimates of the utilization of lipid energy reserves in pueruli. For biochemical energy reserves reported for pueruli collected 20 km off the east coast of New Zealand, the model suggests that this distance and durations of 5 days active swimming are the approximate limits to endurance. Sustained swimming exceeding 15 cm s− 1 will likely exhaust energy reserves before an animal can reach the coast, whereas swimming at less than 5–7 cm s− 1 is inefficient because of the overhead of nonswimming, inactive metabolism. Successful onshore migration of this species is potentially limited by the animals' energy reserves. Reduced energy reserves at the outset due to prior poor feeding, or delays encountered en route due to unfavorable currents, could lead to exceeding the stored reserves of the pueruli, and death. Potentially, relatively small shifts in coastal ocean climate conditions could generate marked changes in recruitment to important spiny lobster fisheries, as has recently been observed in many coastal populations of spiny lobsters.

Reproductive success of planktivorous seabirds in the North Pacific is related to ocean climate on decadal scales

Growing evidence indicates relationships between seabird demography and both large- and small-scale variation in climate and oceanography, yet few studies have examined multiple species and locations simultaneously. As secondary consumers, least, whiskered, and crested auklets (Aethia pusilla, A. pygmaea, and A. cristatella, respectively), congeneric planktivorous seabirds endemic to the Bering and Okhotsk seas, are expected to respond to changes in ocean climate due to their low trophic positioning. From 1990 to 2008, we measured reproductive success (productivity) and breeding phenology (mean hatching date) of auklets on Buldir, Kiska, and Kasatochi, 3 islands spanning 585 km across the Aleutian Islands, Alaska, USA. A model including Island, Species, and Winter Aleutian Low Pressure Index (ALPI) best explained productivity, with reproductive success decreasing among all species with increasing ALPI (β = -0.273 ± 0.0263 (SE)), likely through control of water temperature and prey (zooplankton) availability. Auklet productivity also increased with increasing winter sea surface temperature (SST) in the western North Pacific and western Bering Sea (and correspondingly decreased with increasing SST in the Gulf of Alaska), and was correlated negatively with spring sea-level air pressure in the North Pacific. These responses are reflective of positive values of the Aleutian low pressure system. Though our datasets cover only 19 yr or less, we found similar correlations between climate and auklet productivity among all species and islands. Together, our results suggest that ocean climatic conditions and reproductive success of plankti- vorous auklets are significantly related.

NORTH ATLANTIC OCEAN BASIN TROPICAL CYCLONE ACTIVITY AS RELATED TO CLIMATE FACTORS FOR THE 2010 HURRICANE SEASON

Atmospheric and oceanic climate factors and conditions play a crucial role in modulating seasonal/annual tropical cyclone activity in the North Atlantic Ocean Basin. In the following, correlations between North Atlantic tropical cyclone activity including frequency of occurrence and pathways are explored, with special emphasis on hurricanes. The value of two-dimensional and three-dimensional data sets representing climate patterns is investigated. Finally, the diagnostic study of historical tropical cyclone and hurricane temporal and spatial variability and relationships to climate factors lead to a statistical prognostic forecast, made in April, 2010, of the 2010 tropical cyclone and hurricane season. This forecast is tested both retrospectively and presently and is shown to be quite accurate. Knowing the probability of the frequency of occurrence, i.e. the numbers of named storms to form in general and the number of hurricanes (NHs) that are likely to form, is important for many societal sectors. However, the reliable forecasts of probable pathways of predicted events, specifically the likely NH land falls along the coastlines of the United States, should have great potential value to emergency planners, the insurance industry, and the public. The forecast provided in this study makes such a prognostication. As the 2010 hurricane season has progressed, an update of the goodness of the forecast is shown to be quite accurate in numbers of named events, hurricanes, major hurricanes (MHs), and landfalls. The mathematical and statistical methodology used in this study, which could be coupled to next generation "empirical modal decomposition," suggests that this may signal a new era in the future of tropical cyclone forecasting, including the reliable prognostication of numbers of events, intensities of events, and the pathways of those events. The ability to reliably predict the probability and location of land falls of these destructive events would be very powerful indeed.

A novel second instar Gasterophilus excretory/secretory antigen-based ELISA for the diagnosis of gasterophilosis in grazing horses

We have developed a novel enzyme-linked immunosorbent assay (ELISA) based on excretory/secretory antigens of second instar Gasterophilus for the diagnosis of gasterophilosis in grazing horses. Between January 2007 and January 2009, two experiments were carried out on free-ranging horses in northwest Spain. During the first year, monthly blood samples were collected from a herd of 25 horses. In the second year, a monthly serological survey was conducted for a total of 398 different horses. All the sera were analyzed by ELISA using excretory/secretory antigens from Gasterophilus intestinalis (GphiL2ES) and Gasterophilus nasalis second-stage larvae (GphnL2ES). Climatic data were collected between January 2007 and January 2009 from local meteorological automated stations to establish the weather pattern in the study area. Observations of Gasterophilus eggs on the horses' hair and third instars passed in the faeces were also done. The kinetics of IgG response decreased against GphiL2ES from January to July, increased slowly from August and rose up to January. After a slight decrease in January, the absorbances against GphnL2ES reduced from April to August, when the lowest values were observed. The IgG values rose until the end of the study in January. Third instars were observed in the faeces in March to May, and Gasterophilus eggs were seen on the horses' hair from June to September. The highest IgG seroprevalences were achieved in winter (January-February; 100%) against both antigens. The lowest percentages of seropositivity were observed in June (3%) to the GphiL2ES, and in July (9%) to the GphnL2ES. The use of antigens from G. intestinalis second-stage larvae was shown to be suitable for diagnosing infestation by G. intestinalis or G. nasalis. We concluded that under oceanic climate conditions, the egg-laying period occurs from late spring, and eggs and first instars are found in the mouth in early summer. During summer the second instars move into the stomach and intestine, where the third-stage larvae remain until the end of winter, when pupation takes place. The adult horse bot fly emerges in the spring. Two treatments for the control of gasterophilosis are suggested: a curative in the summer to eliminate the first instars and a preventive in the autumn to suppress the second instars.

Improving the fatty acid profile of dairy cow milk by combining grazing with feeding of total mixed ration

Grazing cows could produce milk with a higher proportion of polyunsaturated fatty acids, which is beneficial to human health, compared with non-grazing cows, though grazing alone could compromise milk production. Under oceanic climate conditions, a study involving 15 dairy cows, fed total mixed ration (TMR) ad libitum in combination with different grazing times of 12 h (TMR12), 6 h (TMR06) and zero grazing time (TMR00) with the aim to evaluate different strategies on the fatty acids profile of milk and milk production. No differences were seen between the treatments with respect to milk yield (34.4+/-6.3 kg/d) or milk protein content (30.4+/-1.8 g/kg). The milk produced by the TMR12 cows had less total fat (36.2 vs. 38.2 g/kg) and saturated fatty acid (FA, 69.39 vs. 71.44 g/100 g FA) than that produced by the TMR00 cows. The concentration of vaccenic acid in the TMR06 and TMR12 milk was twice that of the TMR00 milk (4.22, 4.09 and 2.26 g/100 g FA respectively). Linear increases in conjugated linoleic (CLA) and linolenic acids were observed with increasing grazing time. Pasture was an important source of FA especially C18:3 for TMR06 and TMR12 cows. Under oceanic climatic conditions, the grazing of dairy cows as a complement to feeding with TMR can improve the FA profile of milk and increase its CLA content.

Seabird nestling diets reflect latitudinal temperature-dependent variation in availability of key zooplankton prey populations

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 393:199-210 (2009) - DOI: https://doi.org/10.3354/meps08223 Seabird nestling diets reflect latitudinal temperature-dependent variation in availability of key zooplankton prey populations Douglas F. Bertram1,2,3,*, Anne Harfenist2,4, April Hedd1,5 1Centre for Wildlife Ecology, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada 2Canadian Wildlife Service, Environment Canada, Pacific Wildlife Research Centre, RR1 5421 Robertson Road, Delta, British Columbia V4K 3N2, Canada 3Present address: Environment Canada, Wildlife Science Division, c/o Institute of Ocean Sciences, 9860 West Saanich Road, PO Box 6000, Sidney, British Columbia V8L 4B2, Canada 4Present address: Harfenist Environmental Consulting, Box 2498, Smithers, British Columbia V0J 2N0, Canada 5Present address: Cognitive and Behavioural Ecology, Departments of Psychology and Biology, Memorial University of Newfoundland, St. John’s, Newfoundland A1B 3X9, Canada *Email: douglas.bertram@dfo-mpo.gc.ca ABSTRACT: We report on historical (1978 to 1982) and more recent (1996 to 2000) variation in the nestling diet of Cassin’s auklet Ptychoramphus aleuticus breeding at Triangle Island (southern) and Frederick Island (northern), British Columbia, Canada; these islands are influenced by the California and the Alaska Current ecosystems, respectively. Ocean climate conditions off the British Columbia coast varied tremendously between 1978 and 2000. At both colonies, the nestling diet was composed largely of copepods and euphausiids, with fish contributing substantially in some of the warmer years at Triangle Island. The copepod Neocalanus cristatus was the single most important prey item at both colonies, and Stage V copepodites dominated in all sampling periods. We used a recently published temperature-dependent phenology equation to estimate the timing of peak biomass of Neocalanus near Triangle and Frederick Islands. During warm water years (such as 1996 and the El Niño of 1998), the timing and duration of N. cristatus availability in surface waters near Triangle Island was early and limited (mismatched) in contrast to cooler years (such as 1999 and 2000), when this prey was available to birds throughout the breeding season (matched). We argue that Cassin’s auklet nestling diet data reflect the temperature-related timing of Neocalanus prey availability to seabirds in surface waters. Our results support the argument that inadequate overlap of prey availability and predator breeding (i.e. temporal trophic mismatch) is more likely on Triangle Island, where zooplankton peaks often occur earlier and are narrower, than on Frederick Island, where prey peaks are later and more protracted. Poor reproductive performance is the biological consequence of such trophic mismatch for Cassin’s auklet. If the frequency of El Niño-like events increases and if ocean temperatures rise in the future, we predict an increase in the frequency of trophic mismatch events in the northeast Pacific Ocean. KEY WORDS: Copepod availability · Ocean temperature · Match-mismatch · Seabirds · Cassin’s auklet Full text in pdf format Supplementary material PreviousNextCite this article as: Bertram DF, Harfenist A, Hedd A (2009) Seabird nestling diets reflect latitudinal temperature-dependent variation in availability of key zooplankton prey populations. Mar Ecol Prog Ser 393:199-210. https://doi.org/10.3354/meps08223Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 393. Online publication date: October 30, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Observations on the relationship between the Antarctic coastal diatoms Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen and sea ice concentrations during the late Quaternary

The available ecological and palaeoecological information for two sea ice-related marine diatoms (Bacillariophyceae), Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen, suggests that these two species have similar sea surface temperature (SST), sea surface salinity (SSS) and sea ice proximity preferences. From phytoplankton observations, both are described as summer or autumn bloom species, commonly found in low SST waters associated with sea ice, although rarely within the ice. Both species form resting spores (RS) as irradiance decreases, SST falls and SSS increases in response to freezing ice in autumn. Recent work analysing late Quaternary seasonally laminated diatom ooze from coastal Antarctic sites has revealed that sub-laminae dominated either by T. antarctica RS, or by P. glacialis RS, are nearly always deposited as the last sediment increment of the year, interpreted as representing autumn flux. In this study, we focus on sites from the East Antarctic margin and show that there is a spatial and temporal separation in whether T. antarctica RS or P. glacialis RS form the autumnal sub-laminae. For instance, in deglacial sediments from the Mertz Ninnis Trough (George V Coast) P. glacialis RS form the sub-laminae whereas in similar age sediments from Iceberg Alley (Mac.Robertson Shelf) T. antarctica RS dominate the autumn sub-lamina. In the Dumont d'Urville Trough (Adélie Land), mid-Holocene (Hypsithermal warm period) autumnal sub-laminae are dominated by T. antarctica RS whereas late Holocene (Neoglacial cool period) sub-laminae are dominated by P. glacialis RS. These observations from late Quaternary seasonally laminated sediments would appear to indicate that P. glacialis prefers slightly cooler ocean–climate conditions than T. antarctica. We test this relationship against two down-core Holocene quantitative diatom abundance records from Dumont d'Urville Trough and Svenner Channel (Princess Elizabeth Land) and compare the results with SST and sea ice concentration results of an Antarctic and Southern Ocean Holocene climate simulation that used a coupled atmosphere–sea ice–vegation model forced with orbital parameters and greenhouse gas concentrations. We find that abundance of P. glacialis RS is favoured by higher winter and spring sea ice concentrations and that a climatically-sensitive threshold exists between the abundance of P. glacialis RS and T. antarctica RS in the sediments. An increase to > 0.1 for the ratio of P. glacialis RS: T. antarctica RS indicates a change to increased winter sea ice concentration (to >80% concentration), cooler spring seasons with increased sea ice, slightly warmer autumn seasons with less sea ice and a change from ~ 7.5 months annual sea ice cover at a site to much greater than 7.5 months. In the East Antarctic sediment record, an increase in the ratio from <0.1 to above 0.1 occurs at the transition from the warmer Hypsithermal climate into the cooler Neoglacial climate (~ 4 cal kyr) indicating that the ratio between these two diatoms has the potential to be used as a semi-quantitative climate proxy.

Relationship between ocean climatic variability and rain-fed agriculture in northeast Brazil

The statistical relationship between sea-surface temperature variability over tropical oceans and the 1952 to 2000 crops of maize and beans in the state of Ceara, Brazil, was investigated. This region mainly receives precipitation from February to May. The climatic indices used were the Nino-3 for the Pacific and the dipole index for the Atlantic. In a first series of diagnostic analyses, the climatic precursor variables were examined from November to January (Years 0 to 1) for the Nino-3 in- dex and from February to April (Year 1) for the Atlantic dipole components. The agronomic variables were the planted area, annual production, yield (which showed a negative linear trend during the study period), price, and aggregate value (price/yield) for Year 1. A more robust statistical weight was obtained with the Atlantic dipole. The Pacific weight added to, or decreased, the Atlantic effect, de- pending on the sign of the index. Ocean climatic conditions that generate drought episodes in the Nordeste region of Brazil are generally associated with bad harvests. However, the reverse (i.e. wet weather episodes) does not necessarily produce good harvests. In a second series of prognostic analy- ses, a statistical model used the ocean climatic information available before the rainy season to forecast the yields of maize and beans. The model gave some relevant data in terms of yield tendencies, and was more sensitive when the climatic conditions were neutral or dry. Remarkably good yield forecasts were noted at the end of the study period. Harvests depend on complex combinations of multiple climatic criteria related, not only to quantitative, but also qualitative factors connected with the rainy season.

Range‐wide reproductive consequences of ocean climate variability for the seabird Cassin's Auklet

We examine how ocean climate variability influences the reproductive phenology and demography of the seabird Cassin's Auklet (Ptychoramphus aleuticus) across approximately 2500 km of its breeding range in the oceanographically dynamic California Current System along the west coast of North America. Specifically, we determine the extent to which ocean climate conditions and Cassin's Auklet timing of breeding and breeding success covary across populations in British Columbia, central California, and northern Mexico over six years (2000-2005) and test whether auklet timing of breeding and breeding success are similarly related to local and large-scale ocean climate indices across populations. Local ocean foraging environments ranged from seasonally variable, high-productivity environments in the north to aseasonal, low-productivity environments to the south, but covaried similarly due to the synchronizing effects of large-scale climate processes. Auklet timing of breeding in the southern population did not covary with populations to the north and was not significantly related to local oceanographic conditions, in contrast to northern populations, where timing of breeding appears to be influenced by oceanographic cues that signal peaks in prey availability. Annual breeding success covaried similarly across populations and was consistently related to local ocean climate conditions across this system. Overall, local ocean climate indices, particularly sea surface height, better explained timing of breeding and breeding success than a large-scale climate index by better representing heterogeneity in physical processes important to auklets and their prey. The significant, consistent relationships we detected between Cassin's Auklet breeding success and ocean climate conditions across widely spaced populations indicate that Cassin's Auklets are susceptible to climate change across the California Current System, especially by the strengthening of climate processes that synchronize oceanographic conditions. Auklet populations in the northern and central regions of this ecosystem may be more sensitive to changes in the timing and variability of ocean climate conditions since they appear to time breeding to take advantage of seasonal productivity peaks.

250 years of sardine and anchovy scale deposition record in Mejillones Bay, northern Chile

Marine oxygen-deficient environments with high sedimentation rates and high primary productivity can provide relevant information regarding variations of ocean–climatic conditions in the past. In the Humboldt current ecosystem, which now hosts huge populations of pelagic fishes (mainly anchovy and sardine), fish scale abundance in the sedimentary record may be useful indicators of environmental change. Here we assess such a proxy record in a 42 cm-long sedimentary core collected from 80 m in Mejillones Bay (23°S, northern Chile). We also analyse fish remains in surface sediment sampled along a bathymetric transect (from 10 to 110 m water depth) in the same bay. In the core-top record, the fluctuations of sardine and anchovy scale deposition rates (SDR) agreed with those of industrial catches for these two species in northern Chile, tending to validate the SDR as a proxy of local fish biomass when bottom anoxic conditions prevail. However, apparent SDR for records prior to 1820 have probably been influenced by dissolution processes linked to the oxygenation of the bottom environment of Mejillones Bay, as suggested by other proxy records. After 1820, the fluctuations in the relative abundance of sardine and anchovy scales point to alternating warm and cold conditions during about 30 years and then a progressively cooler period. Since ca. 1870, marked fluctuations of SDR of both species are observed, probably as a consequence of the onset of a different oceanographic regime characterized by intensified upwelling, stronger subsurface oxygen deficiency, higher primary productivity, and enhanced “ENSO-like” interdecadal variability. While anchovy SDR fluctuated in periods of 25–40 years, only two peak periods of sardine SDR occurred (late 19th century and late 20th century), suggesting that sardine abundance depends on other ocean–climatic factors.

Organic composition of atmospheric urban aerosol: Variations and sources of aliphatic and polycyclic aromatic hydrocarbons

The non-polar organic composition of airborne particulate matter was analysed over a two year period in an urban area under oceanic climate conditions (Errenteria, Basque Country, Spain). In addition, the distribution of polycyclic aromatic hydrocarbons (PAH) among different aerosol particle sizes was determined. Clues as to the origin of various particle types were gained by using scanning electron microscopy to view the morphology of the particulates in each size fraction. Samples were collected on glass fibre filters and analysed by means of soxhlet extraction and gas chromatography (either with a flame ionization detector or coupled to a mass spectrometry). In general, total PAH levels were moderate (0.96–50 ng m − 3 ) as compared to other studies conducted in Europe, and showed clear seasonal variation with maxima in winter and minima in summer. Vehicular traffic was identified as a major source of PAHs in the study area. Regarding particle size, a bimodal distribution was observed. The large sized particles exhibited an apparent seasonal variation with higher concentrations in winter than in summer. The dependences between particle size, PAH distribution and meteorological variables were studied with multivariate statistics. Three main sources of organic compounds were identified: combustion, vegetation, and atmospheric oxidation.