Global distribution of summer chlorophyll blooms in the oligotrophic gyres

Chlorophyll blooms consistently develop in the oligotrophic NE Pacific in late summer, isolated from land masses and sources of higher chlorophyll waters. These blooms are potentially driven by nitrogen fixation, or by vertically migrating phytoplankton, and a better understanding of their ubiquity could improve our estimate of the global nitrogen fixation rate. Here, global SeaWiFS chlorophyll data from 1997 to 2007 are examined to determine if similar blooms occur in other oligotrophic gyres. Our analysis revealed blooms in five other areas. Two of these are regions where blooms have been previously identified: the SW Pacific and off the southern tip of Madagascar. Previously, unnoticed summer blooms were also identified in the NE and SW Atlantic and in a band along 10°S in the Indian Ocean. There is considerable variation in the intensity and frequency of blooms in the different regions, occurring the least frequently in the Atlantic Ocean. The blooms that develop along 10°S in the Indian Ocean are unique in that they are clearly associated with a hydrographic feature, the 10°S thermocline ridge, which explains the bloom within a conventional upwelling scenario. The environment and timing of the blooms, developing in oligotrophic waters in late summer, are conducive to both nitrogen fixers and vertically migrating phytoplankton, which require a relatively stable water column. However, the specific locations of the chlorophyll blooms generally do not coincide with areas of maximum levels of nitrogen fixation or Trichodesmium. The NE Pacific chlorophyll blooms develop in a region with a very high SiO₄/NO₃ ratio, where silicate will not be a limiting nutrient for diatoms. The blooms often develop between eddies, wrapping around the periphery of anti-cyclonic features. However, none of the areas where the blooms develop have particularly high eddy kinetic energy, from either a basin-scale or a mesoscale perspective, suggesting that other factors, such as interactions with a front or dynamics associated with the critical latitude, operate in conjunction with the eddy field to produce the observed blooms.     

Evaluation of the performance of HPLC–CHEMTAX analysis for determining phytoplankton biomass and composition in a turbid estuary (Schelde, Belgium)

In the upper Schelde estuary in 2002, phytoplankton biomass and community composition were studied using microscopic and pigment analyses. Chlorophyll a concentration was a good predictor of phytoplankton biomass estimated from cell counts and biovolume measurements. The phytoplankton carbon to chlorophyll a ratio, however, was often unrealistically low (<10). CHEMTAX was used to estimate the contribution of the major algal groups to total chlorophyll a. The dominant algal groups were diatoms and chlorophytes. While diatom equivalents in chlorophyll a predicted diatom biomass relatively well, chlorophyte equivalents in chlorophyll a were only weakly related to chlorophyte biomass. The pigment-based approach to study phytoplankton overestimated phytoplankton biomass in general and chlorophyte biomass in particular in late autumn and winter, when phytoplankton biomass was low. A possible explanation for this overestimation may be the presence of large amounts of vascular plant detritus in the upper Schelde estuary. Residual chlorophyll a, chlorophyll b and lutein in this detritus may result in an overestimation of total phytoplankton and chlorophyte biomass when the contribution of phytoplankton to total particulate organic matter is low.     

Inter-annual variability in phytoplankton summer blooms in the freshwater tidal reaches of the Schelde estuary (Belgium)

The inter-annual variability in phytoplankton summer blooms in the upper reaches of the Schelde estuary was investigated between 1996 and 2005 by monthly sampling at 10 stations. The large inter-annual variations of the chlorophyll a concentration in the freshwater tidal reaches were independent from variations in chlorophyll a in the tributary river Schelde. Summer mean chlorophyll a concentrations were significantly negatively correlated with flushing rate (Spearman correlation: r = −0.67, p = 0.05, n = 9) but not with temperature, irradiance and suspended particulate matter or dissolved silica (DSi) concentrations. During dry summers, low flushing rates permitted the development of dense phytoplankton populations in the upper part of the estuary, while during wet summers high flushing rates prevented the development of dense phytoplankton blooms. Flushing rate was also found to be important for the phytoplankton community composition. At low flushing rates, the community was dominated by diatoms that developed within the upper estuary. At high flushing rates, chlorophytes imported from the tributary river Schelde became more important in the phytoplankton community. The position of the chlorophyll a maximum shifted from the head of the estuary when flushing rates were low, to more downstream when flushing rates were high. Although DSi concentrations tended to be lower during years of high phytoplankton (mainly diatom) biomass, the relation with flushing rate was not significant.     

Evaluation of policy options for the live reef food fish trade in the province of Palawan,Western Philippines

The live reef food fish (LRFF) trade has an estimated annual retail value of US$1 billion in the Asia-Pacific region and at least US$30 million in the Philippines. Palawan Province is the trade's center accounting for as much as 55% of the commodity's total export. Concern about the LRFF trade has caused the Palawan Provincial government to take action to regulate the trade. Four key policy options to address the short-term policy objective of developing a sustainable LRFF industry through the reduction of threats associated with destructive fishing and overfishing were proposed. These four policy options and associated analyses were presented to stakeholders at three separate policy consultations. The stakeholders reached a consensus that a regulated LRFF trade was the most sensible option. As a result, the Provincial Government of Palawan took action to enact “The Palawan Live Reef Fish Ordinance of 2006”, which provides for the sustainable and integrated regulation of the LRFF industry. This provincial ordinance will assist in crafting a national policy for the LRFF trade and may also be useful in revising the 1998 Philippine Fisheries Code. The key challenge is how to translate the ordinance provisions into effective on-the-ground actions.     

Managing by principle: A critical analysis of the European principles of Integrated Coastal Zone Management (ICZM)

A set of eight principles is contained in the European Recommendation on Integrated Coastal Zone Management. The principles have been adopted with the minimum of critical review. The six core principles form two groups, one concerned with strategic goals and one that has a local focus. The principles are presented as a menu of free-standing options, with no prioritization either within or between groups. This can produce irreconcilable differences in strategy. The principles require clarification, prioritization of the strategic principles and recognition that they are an indivisible integrated set which should not be used to select principles to advance a particular agenda.     

Evaluating the Geographic in GIS

Despite several decades of discussion and debate around the role of GIS in the discipline of Geography, it would be a stretch to argue that GIS has not irreversibly altered the discipline, both in the scope of research and teaching as well as in the wider imagination of a general public. However, it remains a challenge to incorporate the range of geographic knowledge, born of a diversity of modalities, into operational insights and analytical pre‐conditions in a GIS. To be certain, some irreconcilability between GIS and geographical inquiry is to be expected, epistemologically speaking. In what follows, we consider what might be meant by a shift to geographic analysis as scholars from disciplines in the humanities and social sciences turn to GIS as a method of observation, interpretation, analysis, and representation. In this context, we engage in a thought experiment and offer some commentary, fixing the notion of information system, while opening the geographic in GIS to more variable understanding. The point is to pursue greater development of GIS theory and method, encompassing, while not reducing, scientific, social scientific, and humanities research.     

Vulnerable groups and preliminary insights into intersecting categories of identity in Laamu Atoll,Maldives

The notion of vulnerability has acquired a significant role in discussions around reducing risk and identifying vulnerable groups, which is particularly important for targeting risk‐reducing policy and practice. Through ten semi‐structured interviews with 24 stakeholders, this study collected local perceptions on the following groups considered most vulnerable in Laamu Atoll, Maldives: youth and children, women, the elderly, people with disabilities, displaced persons and migrants, and farmers. In doing this, the significance of intersecting categories of identity for understanding vulnerability emerged and was explored; an approach that is often absent or scarcely applied in studies that identify vulnerable groups in the Maldives and elsewhere. Intersections between location, youth and gender or disability, as well as gender and marital status emerged as relevant for the Laamu Atoll context. Although this study acknowledges the incompleteness of its intersectional analysis, these findings provide important preliminary insights into the role of intersectionality in shaping vulnerability experience. To enhance scholarship on vulnerability, future studies could further explore intersectionality in Laamu Atoll and the Maldives using this study as a base and also improve its practical applicability for policy and practice.     

The Symbolic Wolf: A Construal Level Theory Analysis of the Perceptions of Wolves in the United States

Charismatic wildlife can be difficult to manage due to the controversies they generate among stakeholders, which may be rooted in their symbolic meaning. Using construal-level theory, we coded the images of gray wolves mentioned by respondents to a national survey (n?=?621) and an issue public survey (n?=?447) as symbolic (abstract) or corporeal (concrete). We analyzed the relationship between these representations of wolves and several perceptions that may perpetuate social conflict. Most people thought of wolves abstractly, and abstract thoughts were associated with positive feelings toward wolves and agreement with existence beliefs regarding wolves. Concrete representations were associated with identifying as a gun or property rights advocate, hunter, or farmer/rancher. Given these disparate views of wolves, engaging stakeholders through collaborative processes designed to foster a shared understanding of this species, while addressing the concerns of those groups, could be useful in reducing conflict concerning wolf management.     

The Distribution of Chadian and earliest Arundian strata in North Wales: Implications for Dinantian (Carboniferous) lithostratigraphy and palaeogeography

The late Chadian Foel Formation, previously thought to be confined to the Dyserth area of North Wales, forms a poorly exposed but persistent basal unit to much of the Dinantian crop east of the Clwydian Range, necessitating a revision of the local lithostratigraphy. The formation comprises a peritidal heterolith which, together with the lowest few metres of the overlying Llanarmon Limestone, yields microfossil assemblages diagnostic of the Eoparastaffella Cf4α Subzone. Succeeding strata, containing the lowest archaediscid foraminifera, provide the first record of Cf4β assemblages from North Wales and establish an early Arundian age for these beds. The Foel Formation was deposited as an aggradational sequence on the northern flank of St. George's Land during a pulsed transgression which began in late Chadian times. The widely recognized basal Arundian transgression is represented by the contact between the Foel Formation and overlying platform carbonates. The latter overlap the Foel Formation in the southernmost part of the Clwydian crop demonstrating, for the first time, southwards onlap on the northern side of the Bala–Bryneglwys Fault System.     

Experimental partitioning of trace elements into schreibersite with applications to IIG iron meteorites

Some of the defining characteristics of the IIG iron meteorite group are their high bulk P contents and massive, coarse schreibersite, which have been calculated to make up roughly 11–14 wt% of each specimen. In this study, we produced two data sets to investigate the formation of schreibersites in IIG irons: measurements of trace elements in the IIG iron meteorite Twannberg and experimental determinations of trace element partitioning into schreibersite. The schreibersite‐bearing experiments were conducted with schreibersite in equilibrium with a P‐rich melt and with bulk Ni contents ranging from 0 to 40 wt%. The partitioning behavior for the 20 elements measured in this study did not vary with Ni content. Comparison of the Twannberg measurements with the experimental results required a correction factor to account for the fact that the experiments were conducted in a simplified system that did not contain a solid metal phase. Previously determined solid metal/P‐rich melt partition coefficients were applied to infer schreibersite/solid metal partitioning behavior from the experiments, and once this correction was applied, the two data sets showed broad similarities between the schreibersite/solid metal distribution of elements. However, there were also differences noted, in particular between the Ni and P contents of the solid metal relative to the schreibersite inferred from the experiments compared to that measured in the Twannberg sample. These differences support previous interpretations that subsolidus schreibersite evolution has strongly influenced the Ni and P content now present in the solid metal phase of IIG irons. Quantitative attempts to match the IIG solid metal composition to that of late‐stage IIAB irons through subsolidus schreibersite growth were not successful, but qualitatively, this study corroborates the striking similarities between the IIAB and IIG groups, which are highly suggestive of a possible genetic link between the groups as has been previously proposed.