Growth and grazing rate dynamics of major phytoplankton groups in an oligotrophic coastal site   总被引：1，自引：0，他引：1  

Andrés Gutiérrez-Rodríguez  Mikel Latasa  Renate Scharek  Ramon Massana  Gemma Vila  Josep M. Gasol 《Estuarine, Coastal and Shelf Science》2011

There has been more attention to phytoplankton dynamics in nutrient-rich waters than in oligotrophic ones thus requiring the need to study the dynamics and responses in oligotrophic waters. Accordingly, phytoplankton community in Blanes Bay was overall dominated by Prymnesiophyceae, remarkably constant throughout the year (31 ± 13% Total chlorophyll a, Tchl a) and Bacillariophyta with a more episodic appearance (20 ± 23% Tchl a). Prasinophyceae and Synechococcus contribution became substantial in winter (Prasinophyceae = 30% Tchl a) and summer (Synechococcus = 35% Tchl a). Phytoplankton growth and grazing mortality rates for major groups were estimated by dilution experiments in combination with high pressure liquid chromatography and flow cytometry carried out monthly over two years. Growth rates of total phytoplankton (range = 0.30–1.91 d⁻¹) were significantly higher in spring and summer (μ > 1.3 d⁻¹) than in autumn and winter (μ ∼ 0.65 d⁻¹) and showed a weak dependence on temperature but a significant positive correlation with day length. Microzooplankton grazing (range = 0.03–1.4 d⁻¹) was closely coupled to phytoplankton growth. Grazing represented the main process for loss of phytoplankton, removing 60 ± 34% (±SD) of daily primary production and 70 ± 48% of Tchl a stock. Chla synthesis was highest during the Bacillarophyceae-dominated spring bloom (Chl a_synt = 2.3 ± 1.6 μg Chl a L⁻¹ d⁻¹) and lowest during the following post-bloom conditions dominated by Prymnesiophyceae (Chl a_synt = 0.23 ± 0.08 μg Chl a L⁻¹ d⁻¹). This variability was smoothed when expressed in carbon equivalents mainly due to the opposite dynamics of C:chl a (range = 11–135) and chl a concentration (range = 0.07–2.0 μg chl a L⁻¹). Bacillariophyta and Synechococcus contribution to C fluxes was higher than to biomass because of their fast-growth rate. The opposite was true for Prymnesiophyceae.  相似文献   

Carbon fluxes through major phytoplankton groups during the spring bloom and post-bloom in the Northwestern Mediterranean Sea     

Andrés Gutiérrez-Rodríguez  Mikel Latasa  Marta Estrada  Montserrat Vidal  Celia Marrasé 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(4):486-500

The carbon flux through major phytoplankton groups, defined by their pigment markers, was estimated in two contrasting conditions of the Northwestern Mediterranean open ocean ecosystem: the spring bloom and post-bloom situations (hereafter Bloom and Post-bloom, respectively). During Bloom, surface chlorophyll a (Chl a) concentration was higher and dominated by diatoms (53% of Chl a), while during Post-bloom Synechococcus (42%) and Prymnesiophyceae (29%) became dominant. The seawater dilution technique, coupled to high pressure liquid chromatography (HPLC) analysis of pigments and flow cytometry (FCM), was used to estimate growth and grazing rates of major phytoplankton groups in surface waters. Estimated growth rates were corrected for photoacclimation based on FCM-detected changes in red fluorescence per cell. Given the 30% average decrease in the pigment content per cell between the beginning and the end of the incubations, overlooking photoacclimation would have resulted in a 0.40 d^?1 underestimation of phytoplankton growth rates. Corrected average growth rates (μ_o) were 0.90±0.20 (SD) and 0.40±0.14 d^?1 for Bloom and Post-bloom phytoplankton, respectively. Diatoms, Cryptophyceae and Synechococcus were identified as fast-growing groups and Prymnesiophyceae and Prasinophyceae as slow-growing groups across Bloom and Post-bloom conditions. The higher growth rate during Bloom was due to dominance of phytoplankton groups with higher growth rates than those dominating in Post-bloom. Average grazing rates (m) were 0.58±0.20 d^?1 (SD) and 0.31±0.07 d^?1. The proportion of phytoplankton growth consumed by microzooplankton grazing (m/μ_o) tended to be lower in Bloom (0.69±0.34) than in Post-bloom (0.80±0.08). The intensity of nutrient limitation experienced by phytoplankton indicated by μ_o/μ_n (where μ_n is the nutrient-amended growth rate), was similar during Bloom (0.78) and Post-bloom (0.73). Primary production from surface water (PP) was estimated with ¹⁴C incubations. A combination of PP and Chl a synthesis rate yielded C/Chl a ratios of 34±21 and 168±75 (g:g) for Bloom and Post-bloom, respectively. Transformation of group-specific Chl a fluxes into carbon equivalents confirmed the dominant role of diatoms during Bloom and Synechococcus and Prymnesiophyceae during Post-bloom.  相似文献   

Pulsating subsidence during a rift episode: stratigraphic and tectonic consequences (Aptian–Albian, northern Spain)     

Joaquín García-Mondéjar  Mikel A. López-Horgue  Arantxa Aranburu  Pedro A. Fernández-Mendiola 《地学学报》2005,17(6):517-525

Backstripping analysis has been carried out on nine outcrop sections of the Basque-Cantabrian Aptian and Albian of northern Spain which consist of shallow-water marine deposits up to 7000 m thick. It reveals four main pulses of common accelerated subsidence: I (Early Aptian), II (Early Albian), III (lower Late Albian), and IV (uppermost Late Albian) separated by tectonic quiescent intervals. Tectonic subsidence rates of 70 m Myr^–1 for the Aptian and 101 m Myr^–1 for the Albian were recorded (Sopuerta section). The calculated stretching factor referred to a pre-rift continental crust of 35 km is (β_s=1.32) and represents approximately 8.5 km of crustal thinning. Points of change towards lesser subsidence rate in the curves are correlated with major unconformities in the sections, in the Basque-Cantabrian Basin and in Boreal Europe, suggesting geodynamic changes related with the opening of Bay of Biscay. Minor variations of spreading direction and intensity are proposed to explain the subsidence pulses.  相似文献   

Response of single benthic metrics and multi-metric methods to anthropogenic pressure gradients, in five distinct European coastal and transitional ecosystems   总被引：4，自引：0，他引：4  

Borja A  Barbone E  Basset A  Borgersen G  Brkljacic M  Elliott M  Garmendia JM  Marques JC  Mazik K  Muxika I  Magalhães Neto J  Norling K  Rodríguez JG  Rosati I  Rygg B  Teixeira H  Trayanova A 《Marine pollution bulletin》2011,62(3):499-513

In recent times many benthic indices have been proposed to assess the ecological quality of marine waters worldwide. In this study we compared single metrics and multi-metric methods to assess coastal and transitional benthic status along human pressure gradients in five distinct environments across Europe: Varna bay and lake (Bulgaria), Lesina lagoon (Italy), Mondego estuary (Portugal), Basque coast (Spain) and Oslofjord (Norway). Hence, 13 single metrics (abundance, number of taxa, and several diversity and sensitivity indices) and eight of the most common indices used within the European Water Framework Directive (WFD) for benthic assessment were selected: index of size spectra (ISS), Benthic assessment tool (BAT), Norwegian quality index (NQI), Multivariate AMBI (M-AMBI), Benthic quality index (BQI), (Benthic ecosystem quality index (BEQI), Benthic index based on taxonomic sufficiency (BITS), and infaunal quality index (IQI). Within each system, sampling sites were ordered in an increasing pressure gradient according to a preliminary classification based on professional judgement. The different indices are largely consistent in their response to pressure gradient, except in some particular cases (i.e. BITS, in all cases, or ISS when a low number of individuals is present). Inconsistencies between indicator responses were most pronounced in transitional waters (i.e. IQI, BEQI), highlighting the difficulties of the generic application of indicators to all marine, estuarine and lagoonal environments. However, some of the single (i.e. ecological groups approach, diversity, richness) and multi-metric methods (i.e. BAT, M-AMBI, NQI) were able to detect such gradients both in transitional and coastal environments, being these multi-metric methods more consistent in the detection than single indices. This study highlights the importance of survey design and good reference conditions for some indicators. The agreement observed between different methodologies and their ability to detect quality trends across distinct environments constitutes a promising result for the implementation of the WFD’s monitoring plans. Moreover, these results have management implications, regarding the dangers of misclassification, uncertainty in the assessment, use of conflicting indices, and testing and validation of indices.  相似文献   

Butyltin compounds,sterility and imposex assessment in Nassarius reticulatus (Linnaeus, 1758), prior to the 2008 European ban on TBT antifouling paints,within Basque ports and along coastal areas     

J. Germán Rodríguez  Itziar Tueros  Ángel Borja  Javier Franco  J. Ignacio García Alonso  Joxe Mikel Garmendia  Iñigo Muxika  Cristina Sariego  Victoriano Valencia 《Continental Shelf Research》2009,29(8):1165-1173

Levels of imposex (superimposition of male characters, upon females) and the presence of sterile females are assessed in the gastropod Nassarius reticulatus (L.), at 35 locations in the Basque Country. At 18 of these localities, organotin bioaccumulation (tributyltin (TBT); dibutyltin; monobutyltin) was evaluated, using isotope dilution GC–ICP–MS. Higher imposex levels and TBT body burden were found in confined harbours, with large vessel traffic or the presence of an offshore fleet. The highest values were found for the port of Pasaia, near to a shipyard (a relative penis size index of up to 92%, and TBT body burden up to 405 ng g^?1 – given on a dry weight basis as Sn). Imposex effects were evaluated also in parasitized females, at some of the sampling sites. The percentage of presence of c-type Vas Deferens sequence stages (i.e., with vas deferens beginning at the oviduct opening) was higher in parasitized females. In turn, there was an absence of highly convoluted oviduct in parasitized females.  相似文献   

Can light intensity cause shifts in natural product and bacterial profiles of the sponge Aplysina aerophoba?          下载免费PDF全文

Oriol Sacristán‐Soriano  Bernard Banaigs  Mikel A. Becerro 《Marine Ecology》2016,37(1):88-105

The potential role of microbial consortia on sponge chemistry is well known. However, how environmental factors affect microbial and chemical profiles and how these shifts affect the sponge holobiont are far from being understood. This study experimentally investigated the effect of light on both the concentration of secondary metabolites and the bacterial assemblages of the sponge Aplysina aerophoba. We quantified major brominated alkaloids (BAs) using a high‐performance liquid chromatography system coupled with a UV‐detector and analysed sponge‐associated bacteria using denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. We identified distinct chemical and bacterial profiles between the ectosome and the choanosome of A. aerophoba. The abundance of most secondary metabolites increased regardless of the illumination regime. We found that the probability of occurrence of three microbial phylotypes (operational taxonomic units 84, 86 and 87) was strongly associated with increasing concentrations of three brominated compounds (aerophobin‐1, aplysinamisin‐1 and isofistularin‐3). Although the role of these bacteria remains uninvestigated, these associations between natural products and specific microbial phylotypes outline further hypotheses that will improve our understanding of the organization and functioning of these complex host–symbiont interactions.  相似文献   

Water Flow, Trophic Depletion, and Benthic Macrofauna Impoverishment in a Submarine Cave from the Western Mediterranean   总被引：1，自引：0，他引：1  

Mikel Zabala  Tecla Riera  Josep Maria Gili  Manel Barange  Agustin Lobo  Josep Peñuelas 《Marine Ecology》1989,10(3):271-287

Abstract. Biotic zonation and severe impoverishment of benthic macrofauna are two of the most conspicuous features of submarine caves. The prevailing explanation assumes trophic depletion caused by reduction of water flow. However, no isolation of water was found in the studied Catalan submarine cave, even in the wall microlayer. Fluorescein diffusion was so fast that it was detectable everywhere in the cave already only a few minutes after the injection. The rate of dissolution of plaster spheres was even greater in the cave than in a nearby tunnel – without benthic macrofauna impoverishment – showing a considerable water flow. The oxygen concentration of water in dialysis bags placed at varying distances from the cave walls showed that no wall microlayer gradients were present.
Biochemical gradients did not indicate any decrease in food supply. Although photosynthetic pigment concentration generally decreased inside the cave, and although the gradients were not linear but formed different patterns throughout the cave, the BOD₅, the POM, the C:N ratio, the [³H]-thymidine incorporation rate, and the ETS activity were higher in the inner part of the cave. There was an accumulation of detritic material and bacteria in the inner parts that constitute a plausible food supply for benthic macrofauna.
If neither water motion nor food supply can be invoked, research into the causes of zonation and disappearence of benthic macrofauna is proposed to be carried out on biotic interactions and behavioural processes.  相似文献   

HPLC analysis of algal pigments: a comparison exercise among laboratories and recommendations for improved analytical performance     

Mikel Latasa  Robert R. Bidigare  Michael E. Ondrusek  Mahlon C. Kennicutt II 《Marine Chemistry》1996,51(4):315-324

Pure individual and mixed pigment standards were distributed among Joint Global Ocean Flux Study (JGOFS) pigment analysts to estimate the variability of their spectrophotometric and chromatographic systems. To monitor the integrity of the pigments during the comparison exercise, chlorophyll and carotenoid standards were archived and periodically analyzed by high-performance liquid chromatography (HPLC). Pigment standards stored in the dark under nitrogen at − 20 °C were found to be stable for periods of at least one year. Results from three separate intercalibration exercises document a better agreement for spectrophotometric analyses than for HPLC. For the spectrophotometric comparisons, 90% of the pigments analyzed by participant laboratories were within ± 6% of the mean “consensus” values. By contrast, 65 and 85% of the laboratories agreed to within ± 10 and ± 20%, respectively, when chromatographic analyses were compared. Chlorophyll absorption measurements obtained with a diode array-type spectrophotometer were 6–9% lower than those obtained with monochromator-type spectrophotometers. These underestimates probably result from chlorophyll fluorescence contamination associated with the optical configuration of the diode array spectrophotometer. It was also determined that HPLC methods which are not capable of separating monovinyl chlorophyll a from divinyl chlorophyll a can produce 15–25% overestimates of total chlorophyll a concentration in Prochlorococcus-dominated oceanic waters. A simple dichromatic approach is described for eliminating this variable source of error caused by co-elution of these structurally-related pigments. The use of internal standards and periodic calibration checks with external standards is highly recommended for improving analytical performance.  相似文献   

Significant implications of permafrost thawing for climate change control     

Mikel González-Eguino  Marc B. Neumann 《Climatic change》2016,136(2):381-388

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On the measurement of pigment concentrations by monochromator and diode-array spectrophotometers     

M. Latasa  R. R. Bidigare  M. E. Ondrusek  M. C. Kennicutt II 《Marine Chemistry》1999,66(3-4)

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