Phaeopigment distribution during the 1990 spring bloom in the northeastern Atlantic

The temporal and depth distributions of phaeopigments were determined during a spring bloom in the northeastern Atlantic in 1990 using reverse phase high performance liquid chromatography. Phaeopigment concentrations were very low (<8% by mole relative to chlorophyll a) and two forms of phaeophorbide and two forms of phaeophytin were separated and quantified. Phaeophorbides were the dominant phaeopigments, accounting for 80% of the total phaeopigment molar concentration, and phaeopigments closely tracked the variations in chlorophyll a by increasing during the development phase of the bloom and decliningin the post bloom stage. Production of phaeopigments was found to occur predominantly at night, and these rates exceeded the rates of phaeopigment destruction during the day. Lower phaeopigment-chlorophyll a ratios were determined for the surface waters, suggesting that photodegradation was possibly the primary mechanism of phaeopigment disappearance in the euphotic zone. A comparison of phaeopigment data and phyto- and zooplankton structure indicates that greater phaeopigment production and grazing pressure occurred in the development phase when diatoms dominated, while grazing and phaeopigment production declined in the post bloom stage dominated by prymnesiophytes.     

An experimental approach to estuarine microplankton ecology

An experimental approach was used in determining which factors, natural or man made, had the greatest impact on estuarine microplankton ecology. In microcosms, filled with natural water of <5‰, 10‰, 18‰ and > 26‰ salinity, the impact of high organic load (glucose), shading, Cu and a heavy metal mixture on the microplankton populations was monitored. Naturally occurring perturbations were of much greater impact to estuarine ecology than the addition of heavy metals in concentrations five to ten times that which are known to occur in moderately polluted estuaries.     

Tomorrow’s Forests: Adapting to A Changing Climate

Today’s forests are largely viewed as a natural asset, growing in a climate envelope, which favors natural regeneration of species that have adapted and survived the variability’s of past climates. However, human-induced climate change, variability and extremes are no longer a theoretical concept. It is a real issue affecting all biological systems. Atmospheric scientists, using global climate models, have developed scenarios of the future climate that far exceed the traditional climate envelope and their associated forest management practices. Not all forests are alike, nor do they share the same adaptive life cycles, feedbacks and threats. Much of tomorrow’s forests will become farmed forests, managed in a pro-active, designed and adaptive envelope, to sustain multiple products, values and services. Given the life cycle of most forest species, forest management systems will need to radically adjust their limits of knowledge and adaptive strategies to initiate, enhance and plan forests in relative harmony with the future climate. Protected Areas (IUCN), Global Biosphere Reserves (UNESCO) and Smithsonian Institution sites provide an effective community-based platform to monitor changes in forest species, ecosystems and biodiversity under changing climatic conditions.     

巴西桑塔纳组可能具有气囊保存的一新神龙翼龙的腰带：功能学和系统发育学的推断

Pterosaur pelves feature prominently in discussions of pterosaur terrestrial locomotion (e.g. Wellnhofer 1988; Bennett 1990), but have otherwise received scant attention.     

Oestrogenic markers and reduced population fertile egg production in a sand goby partial life-cycle test

Understanding the ecological significance of oestrogenic biomarker responses, seen in field surveys of some UK estuarine fish, requires a suitable model to link biochemical and reproductive effects. The sand goby (Pomatoschistus minutus) is a common inshore fish that has been successfully bred in laboratory aquaria. Juvenile sand goby were continuously exposed to 17beta-oestradiol (E2) during gonadal maturation, and their subsequent reproductive success investigated. Exposure endpoints included hepatic vitellogenin (VTG) mRNA expression and maturation (male nuptial colouration, sperm duct gland- and gonado-somatic indices (SDGSI, GSI)). Reproductive endpoints included spawning behaviour, brood size, fertility and population-level fertile egg production. Measured E2 exposure concentrations were <5 (controls), 17, 71 and 530 ngl(-1). Male maturation decreased with increasing E2 concentration. VTG mRNA expression increased with E2 concentration, but not with duration of exposure. Reproductive endpoints showed progressive impairment with increasing E2 concentration. For most endpoints, the lowest observed effect concentration (LOEC) was 71 ngl(-1), and EC50s were in the range 87-165 ngl(-1). Pre-breeding male colouration, VTG expression and SDGSI were good predictors of subsequent population-level fertile egg production, but GSI was not. The sensitivity of oestrogenic markers in sand goby are comparable to those used in other species, and feral fish populations exhibiting such oestrogenic responses at molecular and organ levels are likely to have reduced fertile egg production.     

The contribution of microzooplankton to the diet of mesozooplankton in an upwelling filament off the north west coast of Spain

Incubation experiments were carried out daily during a Lagrangian experiment within an upwelled filament off the Galician coast to determine the importance of microzooplankton in the diet of calanoid copepods. Despite low chlorophyll concentrations the microzooplankton formed the minor component of the diet of the copepod community (7 to 15% of carbon ingested through autotrophic and heterotrophic prey). Ingestion of ciliates was greater than that of heterotrophic dinoflagellates, which reflected a higher abundance of ciliates in the water column. Heterotrophic nanoflagellates appeared also to be consumed by the copepods, although the very small size fraction (2–5μm) was probably not grazed by the larger copepods of Calanus spp. Grazing pressure by the copepods enumerated in the net samples was not sufficient to impact significantly the microzooplankton populations (2 to 51% of daily microzooplankton production was removed). Allometric relationships of grazing on microzooplankton for a range of numerically dominant copepod species are developed from the experimental results. The grazing pressure of the whole copepod community is estimated from these relationships. By considering the total mesozooplankton community we suggest that microzooplankton growth was probably restricted by metazoan grazers.     

Cartographic Visualization: An Assessment and Epistemological Review*

This article examines the concept of cartographic visualization. The value of cartographic visualization as an essential component in the study of geographic phenomena is discussed. Ontological and epistemological perspectives are addressed, with examinations of positivist, realist, postmodern, feminist, and anarchist approaches to visualization. Critiques of cartographic visualization from social theorists and quantitative positivists are presented. The author asserts that cartographic visualization is not restricted to any one particular epistemological framework but may combine methods of knowledge production. For comprehensive analysis of spatial data, cartographic visualization must be included along with other qualitative and quantitative analysis.     

Scenarios for Community-based Approaches to Biodiversity Conservation: a case study from the Wet Tropics,Queensland, Australia

Natural resource management approaches that deliver biodiversity conservation remain elusive, with evidence of a persistent implementation gap between biodiversity science and conservation projects. Scenarios have been identified as potentially useful in addressing the complex issues underlying this implementation gap, but have been infrequently applied to biodiversity conservation. Our paper reports on action co-research to develop, apply and assess the efficacy of scenarios within a community-based natural resource management (CBNRM) approach to biodiversity conservation at Mission Beach, a key site within the globally significant Wet Tropics bioregion. We focused on the capacity of scenarios to address the issues of contested interests and uncertainty, aiming specifically to engage the community to build a cohesive vision. The scenarios' headline messages included a projected substantial loss of habitat in coastal vegetation communities that are highly valued by all stakeholders. Our assessment identified that the use of scenarios fulfilled the intended aims, resulting in a vision for biodiversity conservation that has substantial community support. Three factors contributed to this efficacy of the scenarios: (1) the focus on threat; (2) biodiversity science integration; and (3) simplicity in presentation. Further investigation of the potential of scenarios as tools to overcome the implementation gap in biodiversity conservation is recommended.     

The herbivorous impact of microzooplankton during two short-term Lagrangian experiments off the NW coast of Galicia in summer 1998

Microzooplankton (heterotrophic microplankton and heterotrophic nanoflagellates) and their herbivorous activity were estimated from dilution experiments in August 1998 during two Lagrangian drift experiments that sampled contrasting conditions—an upwelling/relaxation event along the shelf edge and an oligotrophic offshore filament. During upwelling/relaxation, heterotrophic microplankton were present at mean surface concentrations between 15,000 and 48,000 cells l⁻¹. Heterotrophic nanoflagellate concentrations were between 200 and 700 cells ml⁻¹ and the most abundant component of the heterotrophic microplankton was the aloricate choreotrich ciliates which increased dramatically in concentration from 6,000 to 24,000 cells l⁻¹ during the first 4 days of the study. Total microzooplankton biomass reached a maximum of 39mgC.m⁻³. In the filament, which developed from the upwelling, cell concentrations were lower and averaged 4,500 cells l⁻¹ for heterotrophic microplankton and 250 cells ml⁻¹ for heterotrophic nanoflagellates. Total microzooplankton biomass was about 10–12mgC.m⁻³. Microzooplankton turned over between 40 and 85% of the phytoplankton standing stock, thereby consuming between 5 and 78mg phytoplankton carbon.m⁻³.d⁻¹. The magnitude of this activity was highest during upwelling/relaxation and was positively correlated to heterotrophic nanoflagellate biomass and chlorophyll-a concentration but not heterotrophic microplankton biomass. The proportion of primary production grazed decreased from 160 to 59% d⁻¹ during upwelling/relaxation and ranged between 60 and 90% d⁻¹ in the filament. Microzooplankton herbivory within the euphotic zone increased from 684 to >2000mgC.m⁻².d⁻¹ during upwelling/relaxation and was between 327 and 802mgC.m⁻².d⁻¹ in the filament. Although microzooplankton herbivory was lower and less variable during the filament study, microzooplankton consumed on average 60% of the phytoplankton standing stocks which was higher than found during upwelling/relaxation. Microzooplankton assimilation efficiency ranged between 3 and 33% during upwelling/relaxation and between 0 and 13% in the filament. Our data demonstrate a close coupling between phytoplankton growth and microzooplankton herbivory in surface waters off the Galician Coast and suggest that microzooplankton may have been a significant sink for phytogenic carbon during August 1998.