Influence of Coupled Rossby Waves on Primary Productivity and Tuna Abundance in the Indian Ocean

Interannual coupled Rossby waves in the extratropical Indian Ocean propagate westward in covarying pycnocline depth, sea surface temperature, and meridional surface wind anomalies from the west coast of Australia between 15°S and 35°S, taking 3–4 years to transit the interior ocean to Madagascar. In the interior subtropical gyre, where the tuna longline catch (TLC) mainly concerns two species (albacore and bigeye), these waves have been observed to affect year-to-year changes in catch, with wave crests (troughs) in the main pycnocline associated with high (low) TLC anomalies. This suggested that tuna longline catch is associated with the entrainment of nutrient-rich pycnocline water into the photic zone and a subsequent increase in primary productivity there. Here, this hypothesis is examined within the context of SeaWiFS chlorophyll concentration (CC). We find the situation the opposite of that expected, with wave crests (troughs) in the main pycnocline associated with low (high) CC anomalies averaged over the photic zone. These results are shown to be consistent with a model relating the anomalous CC tendency to upper-layer divergence in the wave, not unlike that relating surface slicks to upper-layer divergence in internal gravity waves. Thus, the connection between interannual coupled Rossby waves and TLC in the interior subtropical gyre does not appear to derive from wave-induced modulation of the pelagic food web. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rip currents, mega-cusps, and eroding dunes

Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline.

The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp.     

Anak Krakatau — a colonization model within a colonization model?

The ppaer re-examines three suggestions previously made concerning the colonization of the Krakatau islands since the extirpating 1883 eruption that involve the more recently emergent volcanic island Anak Krakatau, which itself suffered a devastating eruption in 1952. The suggestions re-addressed in the light of recent comments by other workers are:

Optically Stimulated Luminescence (OSL) dating of sand‐filled wedge structures and their fine‐grained host sediment from Jonzac,SW France

Two sand wedge structures and their host sediments, from Jonzac in SW France, were successfully dated using Optically Stimulated Luminescence (OSL) measurements on both small aliquots and single grains of quartz from the 180–212 μm size fraction. One of the sand wedges clearly contains primary infilling. However, grain‐size analysis and field observations do not clearly indicate whether the other feature represents a primary sand wedge or a composite sand wedge with primary and secondary infilling. OSL results and the geological setting justify using the Central Age Model (CAM) for the calculation of age estimates. Grain‐size analysis and detailed investigations of OSL results revealed the contamination of one sand wedge sample with host sediment. However, age calculation using the Finite Mixture Model (FMM) provided what is considered to be a reliable age estimate for the contaminated sample. The age estimates for all samples correspond to Marine Isotope Stage (MIS) 3. While fine‐grained sediments were deposited in the middle of MIS 3 (c. 43–55 ka), the sand wedges unexpectedly correspond to the end of this period (c. 33 ka) or the onset of MIS 2 (c. 27 ka). The sand wedges were probably formed during intense but short cold periods, possibly correlated with a Heinrich event (H2 and/or H3). The results help us to assess how effective luminescence dating is on sand wedges and the limitations involved in correlating sand wedge ages with Heinrich events, and contribute to the debate on the timing of cryogenic formation processes and the permafrost distribution in SW France.     

Avoiding deforestation in Panamanian protected areas: An analysis of protection effectiveness and implications for reducing emissions from deforestation and forest degradation

Reducing greenhouse gas emissions from deforestation and forest degradation (REDD) is likely to be central to a post-Kyoto climate change mitigation agreement. As such, identifying conditions and factors that will shape the success or failure of a reduced deforestation scheme will provide important insights for policy planning. Given that protected areas (PAs) are a cornerstone in forest conservation, we draw on interviews and secondary data to analyze the effects of available PA resources, governance ability, the level of community involvement, and provincial deforestation rates on land-cover change in nine PAs in Panama. Our results illustrate that coupling surveillance measures with greater funding and strong governance are paramount to reducing deforestation. Alone, however, these factors are insufficient for forest protection. We argue that conservation approaches that complement effective surveillance with community participation and equitable benefit sharing will address the wider issues of leakage and permanence.     

Science-based and stakeholder-driven marine protected area network planning: A successful case study from north central California

The planning process for California's Marine Life Protection Act in north central California represents a case study in the design of a regional component of a statewide network of marine protected areas (MPAs) for improved ecosystem protection. We describe enabling factors, such as a legislative mandate, political will, and adequate capacity and funding that fostered a successful planning process. We identify strategic principles that guided the design of a transparent public planning process that delivered regional MPA network proposals, which both met science guidelines and achieved a high level of support among stakeholders. We also describe key decision support elements (spatial data, planning tools, and scientific evaluation) that were essential for designing, evaluating, and refining alternative MPA network proposals and for informing decision-makers.     

Practicing community geography in times of crisis

Community geography emphasizes the centrality of community engagement to socially transformative research. This introduction to a special issue of GeoJournal on community geography outlines how this growing subfield provides a model for collaborative action with the crises of our time, from white supremacy through climate change. As the co-editors of this special issue, we summarize the contents of these 14 articles, grouping them by the shared themes of power, institutional partnerships, pedagogy, and methods.

     

A watershed-based adaptive knowledge system for developing ecosystem stakeholder partnerships

This study proposes a Watershed-based Adaptive Knowledge System(WAKES) to consistently coordinate multiple stakeholders in developing sustainable partnerships for ecosystem management.WAKES is extended from the institutional mechanism of Payments for Improving Ecosystem Services at the Watershed-scale(PIES-W).PIES-W is designed relating to the governance of ecosystem services flows focused on a lake as a resource stock connecting its inflowing and outflowing rivers within its watershed.It explicitly realizes the values of conservation services provided by private land managers and incorporates their activities into the public organizing framework for ecosystem management.It implicitly extends the "upstream-to-downstream" organizing perspective to a broader vision of viewing the ecosystems as comprised of both "watershed landscapes" and "marine landscapes".Extended from PIES-W,WAKES specifies two corresponding feedback:Framework I and II.Framework I is a relationship matrix comprised of three input-output structures of primary governance factors intersecting three subsystems of a watershed with regard to ecosystem services and human stakeholders.Framework II is the Stakeholder-and-Information structure channeling five types of information among four stakeholder groups in order to enable the feedbacks mechanism of Framework I.WAKES identifies the rationales behind three fundamental information transformations,illustrated with the Transboundary Diagnostic Analysis and the Strategic Action Program of the Bermejo River Binational Basin.These include(1) translating scientific knowledge into public information within the Function-and-Service structure corresponding to the ecological subsystem,(2) incorporating public perceptions into political will within the Serviceand-Value structure corresponding to the economic subsystem,and(3) integrating scientific knowledge,public perceptions and political will into management options within the Value-and-Stakeholder structure corresponding to the social subsystem.This study seeks to share a vision of social adaptation for a global sustainable future through developing a network to adopt contributions from and forming partnerships among all ecosystem stakeholders.     

Interplay of geomorphic and hydrogeologic features at reach- and channel unit-scales on riverbed hydrology and hydrochemistry: a conceptual model in the Lower Coal Measures, South Yorkshire, UK

A conceptual model of groundwater and surface-water interactions in areas of minor aquifers has been developed. It assesses the interplay of reach-scale subsurface flow paths (RSSF), controlled by the lateral extent of the alluvial valley, and channel unit-scale hyporheic flow paths (CUSHF), controlled by riffle and run/pool sequences, and their impacts on the spatial variability of riverbed flow and solute exchange. A network of riverbed mini-piezometers and multi-level samplers in different reach- and channel-unit scale settings of the River Don (South Yorkshire, UK) is monitored to: (1) estimate vertical hydraulic gradients (VHGs) and specific discharge; (2) discriminate subsurface flow paths from conservative natural tracers; and (3) deduce biogeochemical processes. In a constrained context (downstream end of the alluvial valley), RSSF discharge favours a homogeneous riverbed hydrochemistry with limited biogeochemical processes and shallow CUSHF. In an unconstrained (open alluvial valley) or asymmetric (bedrock outcropping on one bank) context, low VHGs favour deep CUSHF and a vertical stratification of RSSF. Reducing conditions intensify with depth, and superimpose with mixing in riffles. This good approximation of flow and solute behaviour in minor aquifers provides a practical framework to understand nutrient and contaminant fate and develop cost-effective monitoring programmes across the groundwater/surface-water interface.