Ostreopsis cf. ovata (Dinophyta) bloom in an equatorial island of the Atlantic Ocean

The epi-benthic dinoflagellate Ostreopsis cf. ovata Fukuyo has an increasingly global distribution. In Brazil there are reports of O. cf. ovata along the coast from 8°S to 27°S latitude and blooms have been registered on the Rio de Janeiro coastline. In the current study, an O. cf. ovata bloom is reported at Saint Paul's Rocks (0°55'10″N; 29°20'33″W), between the southern and northern hemispheres. The Archipelago is not inhabited and not subjected to eutrophication, due to isolation, and sustains a number of endemic species. Therefore, blooms of O. cf. ovata may potentially cause demise to trophic chains by affecting marine invertebrates and vertebrates.     

Mapping seascapes of international environmental arrangements in the Coral Triangle

The Coral Triangle Initiative on Coral Reefs, Fisheries and Food Security (CTI), adopted recently in response to the degradation of coastal and marine environments in the Southeast Asia-Pacific’s Coral Triangle, emphasises the need for using existing international and regional fora to promote implementation. Large-scale marine initiatives, including the CTI, very often must contend with a remarkably complex institutional system. This raises the question of whether and how such complexity can be conducive to marine resources management. To answer this question, this paper aims to better understand the governance context in which the CTI was established (i.e., map governance fragmentation/complexity), and explore how such a context may support the implementation of the CTI goals (i.e., examine normative interplay). To conduct this examination, it uses an objective method that allows users to view and explore institutional arrangements through a network approach. By documenting the system of existing institutions in the Coral Triangle, the study shows that the Coral Triangle governance system is illustrative of those of international environmental governance. It involves multiple policy domains, and features different institutional arrangements and variability in terms of geographical scope and main subject matter. Such a system is complex and fragmented, marked by jurisdiction and functional overlaps. The paper suggests interplay management, such as inter-institutional learning and enhancing institutional synergy, as a promising process to promote inter-institutional coordination.     

Macroalgae blooms and δN in subtropical coastal lagoons from the Southeastern Gulf of California: Discrimination among agricultural, shrimp farm and sewage effluents

Macroalgae blooms of Gracilaria vermiculophylla, Hypnea spinella and Spyridia filamentosa have been found in coastal lagoons in the SE Gulf of California. Agriculture, livestock, shrimp and poultry farms and sewage contribute anthropogenic nitrogen to the systems. The δ¹⁵N of these sources, water column and macroalgae were studied in order to identify the N supply for macroalgae blooms. δ¹⁵N of three species of macroalgae (4.3-13.6‰) were enriched compared to the water column ( 3.7-6.8‰), probably because of fractioning from the macroalgae. δ¹⁵N of POM (1.4-10.3‰) was similar to the water column but the relationship was unclear. Depending on the site, macroalgae showed different δ¹⁵N values since some sites receive more or less influence from one given source of the associated watershed, which is reflected in the different δ¹⁵N values of the macroalgae of the same system and in the relative contributions of the sources.     

Environmental controls on drainage behavior of an ephemeral stream

Streambed drainage was measured at the cessation of 26 ephemeral streamflow events in Rillito Creek, Tucson, Arizona from August 2000 to June 2002 using buried time domain reflectometry (TDR) probes. An unusual drainage response was identified, which was characterized by sharp drainage from saturation to near field capacity at each depth with an increased delay between depths. We simulated the drainage response using a variably saturated numerical flow model representing a two-layer system with a high permeability layer overlying a lower permeability layer. Both the observed data and the numerical simulation show a strong correlation between the drainage velocity and the temperature of the stream water. A linear combination of temperature and the no-flow period preceding flow explained about 90% of the measured variations in drainage velocity. Evaluation of this correlative relationship with the one-dimensional numerical flow model showed that the observed temperature fluctuations could not reproduce the magnitude of variation in the observed drainage velocity. Instead, the model results indicated that flow duration exerts the most control on drainage velocity, with the drainage velocity decreasing nonlinearly with increasing flow duration. These findings suggest flow duration is a primary control of water availability for plant uptake in near surface sediments of an ephemeral stream, an important finding for estimating the ecological risk of natural or engineered changes to streamflow patterns. Correlative analyses of soil moisture data, although easy and widely used, can result in erroneous conclusions of hydrologic cause—effect relationships, and demonstrating the need for joint physically-based numerical modeling and data synthesis for hypothesis testing to support quantitative risk analysis.     

Out of administrative control: Absentee owners, resident elk and the shifting nature of wildlife management in southwestern Montana

This paper describes the historical roots of an ongoing wildlife management dilemma involving decreasing opportunities for elk management via public hunting on private land in the context of an expanding elk presence on private land in southwest Montana. Our main focus is on the role of private ranchland in elk ecology, and the ability of land owners to set elk migration in new directions through cumulative decisions about hunting and tolerating elk. This takes elk management, traditionally the purview of the state, out of administrative control. We document connections between the region’s historical and emerging land tenure patterns, and analyze associated changes in hunter access. Elk numbers expanded rapidly in the Upper Yellowstone Valley at a moment of significant transition in ranchland tenure. New owners more interested in natural amenities than in livestock production encouraged the elk and discouraged hunting. This reinforced the spread of elk, and further weakened the ability of the state and other ranchers to manage elk (which interfere with livestock production in numerous ways). Though elk and cattle use the landscape in similar ways, elk became more effective agents of landscape change in a reflexive relationship with ideas of land that stress natural amenities over production.     

Spatial and seasonal variability of polygonal tundra water balance: Lena River Delta, northern Siberia (Russia)

The summer water balance of a typical Siberian polygonal tundra catchment is investigated in order to identify the spatial and temporal dynamics of its main hydrological processes. The results show that, besides precipitation and evapotranspiration, lateral flow considerably influences the site-specific hydrological conditions. The prominent microtopography of the polygonal tundra strongly controls lateral flow and storage behaviour of the investigated catchment. Intact rims of low-centred polygons build hydrological barriers, which release storage water later in summer than polygons with degraded rims and troughs above degraded ice wedges. The barrier function of rims is strongly controlled by soil thaw, which opens new subsurface flow paths and increases subsurface hydrological connectivity. Therefore, soil thaw dynamics determine the magnitude and timing of subsurface outflow and the redistribution of storage within the catchment. Hydraulic conductivities in the elevated polygonal rims sharply decrease with the transition from organic to mineral layers. This interface causes a rapid shallow subsurface drainage of rainwater towards the depressed polygon centres and troughs. The re-release of storage water from the centres through deeper and less conductive layers helps maintain a high water table in the surface drainage network of troughs throughout the summer.