Between a Rock and a Hard Place: Habitat Selection in Female-Calf Humpback Whale (Megaptera novaeangliae) Pairs on the Hawaiian Breeding Grounds

The Au'au Channel between the islands of Maui and Lanai, Hawaii comprises critical breeding habitat for humpback whales (Megaptera novaeangliae) of the Central North Pacific stock. However, like many regions where marine mega-fauna gather, these waters are also the focus of a flourishing local eco-tourism and whale watching industry. Our aim was to establish current trends in habitat preference in female-calf humpback whale pairs within this region, focusing specifically on the busy, eastern portions of the channel. We used an equally-spaced zigzag transect survey design, compiled our results in a GIS model to identify spatial trends and calculated Neu's Indices to quantify levels of habitat use. Our study revealed that while mysticete female-calf pairs on breeding grounds typically favor shallow, inshore waters, female-calf pairs in the Au'au Channel avoided shallow waters (<20 m) and regions within 2 km of the shoreline. Preferred regions for female-calf pairs comprised water depths between 40–60 m, regions of rugged bottom topography and regions that lay between 4 and 6 km from a small boat harbor (Lahaina Harbor) that fell within the study area. In contrast to other humpback whale breeding grounds, there was only minimal evidence of typical patterns of stratification or segregation according to group composition. A review of habitat use by maternal females across Hawaiian waters indicates that maternal habitat choice varies between localities within the Hawaiian Islands, suggesting that maternal females alter their use of habitat according to locally varying pressures. This ability to respond to varying environments may be the key that allows wildlife species to persist in regions where human activity and critical habitat overlap

Land degradation and the problem of sustainable agricultural development

Humanity's welfare is inextricably linked to the land such that a world at peace depends on productive and sustainable agriculture. Food security has been improving for a decade or more but it now appears that some of the increase in production has been won at the price of land degradation. There are well-grounded fears that many current land management practices are unsustainable

Agriculture and Peace

Over 60% of the world's people live in rural areas and are involved either directly or indirectly in agricultural enterprises: in Asia and Africa the proportion is over 70% (Table 1). 1 A thorough appreciation of this statistic must predicate any discussion about cooperative peace strategies. Strategies for building peace must be applicable and effective in rural communities and address their circumstances and constraints. People living in rural areas are predominantly in developing countries (Table 1) where they are likely to live in small self-reliant communities, and have a world view largely shaped by traditional value systems and by local community and family needs but suffer poor access to education, medical facilities, infrastructure, and information

Estimating the contribution of preferential flow to subsurface runoff from a hillslope using deuterium and chloride

The concentrations of deuterium and chloride in rainfall, soil water and throughflow are reported for flow components through a mid-level gently sloping hillside podzolic soil with a well developed network of macropores. The deuterium and chloride signatures of the throughflow are shown to resemble that of rainfall rather than soil water for all rainfall events. Flow through macropores is considered to be the major mechanism for infiltration and throughflow. During the initial stages of rainfall, infiltrating water bypasses much of the soil matrix and a transient water table is established. Storage associated with this water table dampens much of the noise from the deuterium and chloride signature of the rainfall while maintaining the mean rainfall signature. The possible implications on the use of stable isotopes and conservative tracers such as chloride for streamflow partitioning are discussed

Hydrologic response of undisturbed soil cores to simulated rainfall

Experiments to characterize runoff and drainage from large undisturbed soil cores obtained from a site under volunteer pasture are presented. The objectives were to evaluate if a simple kinematic wave model could be used to characterize drainage under conditions of by-passing flow and to investigate the variability of runoff generation under wet and dry antecedent conditions in this well structured soil. Cores were taken to depths of 0.4 and 0.7 m, with six cores obtained from each depth. Results show that variations in soil structure between cores have a greater influence on the hydrologic response than variations in antecedent water content. It may be inferred that, in this soil, good structural continuity substantially enhances soil drainage and, in consequence, decreases surface runoff. During wetting, kinematic celerities ranged from 337 to 3200 mm h-1 in the short cores and from 357 to 1400 mm h-1 in the long cores. The corresponding estimated ranges of mobile or 'macropore' fractions were from 0.015 to 0.154 m3 m-3 in the short cores and 0.033 to 0.132 m3m-3 in the long cores. Both parameters were approximately log-normally distributed. Measured drainage hydrographs were reasonably well described by the kinematic model but the physical significance of the model parameters was unclear

The influence of macropores on runoff generation from a hillslope soil with a contrasting textural class

The hydrological response of a well-structured hillslope soil under pasture is described. In this soil, during the winter recharge period, macropores provide pathways for water movement which effectively by-pass the soil matrix. In consequence, a perched water table does not develop within the soil profile. New input water is able to penetrate rapidly through the macropore system within the clayey B horizon to the soil/bedrock interface. A highly transient ‘water table’ is then established within the macropore system and overland flow commences only when the capacity of this system is exceeded. During the summer, this flow pattern changes and, although the soil might be expected to absorb water more readily than during winter, overland flow is the dominant runoff mechanism. The macropore-matrix dichotomy of the soil hydraulic properties is characterized in situ using auger hole and disc permeaters. The measured soil hydraulic properties are used in a finite element model to predict independently the subsurface runoff response during the winter recharge period and to check the adequacy of a throughflow collection system. The model predictions are in reasonable agreement with measured water tables during drainage

Seasonal changes in pathways of dissolved organic carbon through a hillslope soil (Xeralf) with contrasting texture

The pathways of dissolved organic carbon (DOC) through a podzolic soil (Xeralf) with strong texture contrast are described. During winter, most of the DOC passes through macropores in the profile and flows laterally through the B horizons. During summer the presence of dry, hydrophobic organic matter on the soil surface and the A1 horizon causes DOC to flow overland. DOC concentrations vary seasonally. Highest concentrations are measured during summer overland flow. For all horizons, the longer the dry period the greater the DOC concentration in the subsequent flow. During storm events there is a marked flushing effect in the B horizons but in the A horizon and the surface, DOC concentrations tend to rise. There was a marked decrease in DOC concentration in flow from the B3 compared to the upper horizons. This may be due to adsorption by fine clays lining the macropores

Reprint of Effect of plant growth on the occurrence and stability of palygorskite, sepiolite and saponite in salt-affected soils on limestone in South Australia

Abstract not availableMelissa B. Fraser, G. Jock Churchman, David J. Chittleborough, Pichu Rengasam