WATER USE RELATIONSHIPS AND PROJECTION CORRESPONDING WITH REGIONAL GROWTH,SEATTLE REGION1

ABSTRACT: The paper outlines both the methods used and the results obtained in a study of the demand for municipal and industrial water for the Seattle region. The study was made as part of a regional water management study program, one objective of which is to “… identify, quantify, and set priorities for all current and future water uses …”. A basic concept in the study of municipal and industrial water use is that the demand for water is derived from the demand for output and the direct services that water provides. Principal characteristics of the study are: (1) Water use is studied by type - residential, commercial, industrial and public -with identification of factors affecting each; (2) Water demands are studied by season as well as on an annual basis; (3) Projections of future water use are tied directly to projections of economic change in the service area; and (4) The effects of alternative policies on water use are estimated. Water use levels are projected under alternative regional growth assumptions provided by the Puget Sound Governmental Conference, a regional planning agency. Thus, the water use planning is consistent with other regional planning programs in this respect. The results can be varied according to changes in specific factors affecting water use. The factors considered in the present study include: single-family residential lot size, distribution of population between single- and multi-family units, per capita water use by multi-family unit residents, and industrial and commercial water use per employee. An income elasticity of demand was estimated for single-family residential water use.     

Effect of temperature on statolith growth of the European squid Loligo vulgaris during early life

Over the past decade, statolith interpretation has resulted in a major advance in our knowledge of squid population-dynamics, but the way in which environmental conditions affect the statolith increment-deposition ratio remains virtually unknown. The object of the present study was to determine the effect of temperature on this process, using tetracycline marks to validate statolith growth in Loligo vulgaris Lamarck, 1798 under rearing conditions equivalent to severe winter (11 °C) and summer (19 °C) temperature regimes. Tetracycline marking was performed every 10 d (at 10, 20, 30, 40, 50 and 60 d of age). The newly hatched squid paralarvae were slightly smaller in summer than those hatched in winter. Survival rates were similar in both cultures, but growth rates (wet mass) of summer squids were double those in winter. At hatching, statoliths were already longer in the summer squids, and growth rates were 2% d⁻¹ as opposed to 0.9% d⁻¹ for winter statoliths. For the dorsal dome area of the statolith, where more increment counts were made, statolith growth was of 3.25 μm d⁻¹ in summer, and daily increment deposition was confirmed in 87% of the statoliths. The slow growth of statoliths at winter temperatures yielded a mean growth of 1.1 μm d⁻¹– insufficient to discern the increments using light microscopy. Subsequent SEM observation enabled only 21% of the winter statoliths to be read; these also indicated a deposition rate of one increment d⁻¹. Since the life span of L. vulgaris is ≃1 yr, squids will experience at least one winter during their life cycle, and this might be visible on the statolith. Received: 28 June 1999 / Accepted: 20 December 1999     

Rapana venosa as an indicator species for TBT exposure over decadal and seasonal scales

Imposex and decline in reproductive output in marine gastropods have been linked to tributyltin (TBT) exposure. This study describes Chesapeake Bay, USA, veined rapa whelk Rapana venosa imposex incidence and sex ratios from 1998 to 2009. Tissue TBT concentrations (ng g^?1) were examined with respect to whelk sex, size, and water temperature at the time of collection, and also to egg case size, hatching success, and veliger diameter. Imposex incidence declined and population sex ratios moved closer to parity from 1998 to 2009. Observed TBT concentrations (ng g^?1) were higher in James River than in Ocean View whelks with higher TBT concentrations observed in males than in females. Exponential declines in TBT concentrations from female-specific first to last clutches within a reproductive season were observed, indicating that whelks depurate TBT through egg case deposition. Egg capsule hatching success and veliger size were similar for female and imposex whelks. The R. venosa imposex levels observed in Chesapeake Bay apparently do not affect the production, release, or viability of larvae.     

Underwater and above-water search patterns of an Arctic seabird: reduced searching at small spatiotemporal scales

How predators vary search patterns in response to prey predictability is poorly known. For example, marine invertebrates may be predictable but of low energy value, while fish may be of higher energy value but unpredictable at large (pelagic schools) or small (solitary benthics) spatial scales. We investigated the search patterns of the thick-billed murre (Uria lomvia), an Arctic seabird feeding on invertebrates, pelagic fish, or benthic fish. Foraging ranges at the Coats Island colony are generally smaller (<240 min per trip) than at larger colonies, and many birds specialize in foraging tactics and diet. Underwater search times for benthic fish were higher than for pelagic fish or invertebrates while above-water search times for pelagic fish were higher than for benthic fish or invertebrates. There were few stops during trips. Total trip time, flying time, number of flights, and number of dives were intercorrelated and increased with prey energy content, suggesting that longer trips involved fewer prey encounters due to selection of higher-quality, but rarer, prey items. Flight times were not Lévy-distributed and seabirds may have used area-restricted searches. The high degree of specialization, apparent absence of information center effects, and reduced above-water searching times may be linked to the relatively small colony size and the resulting short commuting distances to feeding areas, leading to greater prey predictability. We concluded that prey predictability over various scales affected predator search patterns.     

Brood reduction in the American white pelican (Pelecanus erythrohynchos)

Summary American white pelicans (Pelecanus erythrorhynchos) breeding in colonies at East Shoal Lake, Manitoba, Canada exhibited a mean hatching asynchrony of 2.5 days in 2-egg clutches. This resulted in a size difference between chicks which facilitated sibling dominance, harassment and lack of food for the subordinate chick. Only one young survived per nest. In marked broods, the secondhatched chick survived in 20% of successful nests. Manipulated clutch sizes (1, 2 and 3 eggs or chicks per nest) revealed that the presence of a second chick contributes significantly to the reproductive success of the parents. Results support the hypothesis that the second egg functions as a form of insurance against early loss of the first egg or chick. The parents, by establishing hatching asynchrony, by nonintervention in sibling aggression, and by selectively feeding the dominant chick, maximize their chance of rearing the most viable young.     

Influence of residency and social odors in interactions between competing native and alien rodents

Residency status of individuals in populations may be an important determinant of the outcomes of interspecific competition between native and introduced species. We examined direct behavioral interactions between two similarly sized rodents, the alien Rattus rattus and native Rattus fuscipes when they were respective residents and intruders in a small enclosure. Resident individuals were dominant in their behaviors toward intruders irrespective of the species that was resident. In contrast, interactive behaviors between conspecifics were often neutral or amicable, supporting suggestions that R. rattus and R. fuscipes are social animals. We then tested whether rodent species use heterospecific odors to avoid aggressive competitive interactions and partition space in the field. Neither R. fuscipes nor R. rattus responded to traps scented with the odors of male or female heterospecifics. If R. fuscipes does not recognize the odor of introduced R. rattus, then odors will not be cues to the presence or territorial space of competing heterospecifics. Rather, findings from both enclosure and field trials suggest that direct aggressive interactions between individual R. rattus and R. fuscipes probably facilitate segregation of space between these two species in wild populations, where resident animals may typically be the winners and exclude heterospecific intruders. These findings have implications for the invasion success of introduced rodents such as R. rattus into intact forests, where native populations may have competitive advantage because of their residency status.     

Patterns of houses and habitat loss from 1937 to 1999 in northern Wisconsin, USA.

Rural America is witnessing widespread housing development, which is to the detriment of the environment. It has been suggested to cluster houses so that their disturbance zones overlap and thus cause less habitat loss than is the case for dispersed development. Clustering houses makes intuitive sense, but few empirical studies have quantified the spatial pattern of houses in real landscapes, assessed changes in their patterns over time, and quantified the resulting habitat loss. We addressed three basic questions: (1) What are the spatial patterns of houses and how do they change over time; (2) How much habitat is lost due to houses, and how is this affected by spatial pattern of houses; and (3) What type of habitat is most affected by housing development. We mapped 27 419 houses from aerial photos for five time periods in 17 townships in northern Wisconsin and calculated the terrestrial land area remaining after buffering each house using 100- and 500-m disturbance zones. The number of houses increased by 353% between 1937 and 1999. Ripley's K test showed that houses were significantly clustered at all time periods and at all scales. Due to the clustering, the rate at which habitat was lost (176% and 55% for 100- and 500-m buffers, respectively) was substantially lower than housing growth rates, and most land area was undisturbed (95% and 61% for 100-m and 500-m buffers, respectively). Houses were strongly clustered within 100 m of lakes. Habitat loss was lowest in wetlands but reached up to 60% in deciduous forests. Our results are encouraging in that clustered development is common in northern Wisconsin, and habitat loss is thus limited. However, the concentration of development along lakeshores causes concern, because these may be critical habitats for many species. Conservation goals can only be met if policies promote clustered development and simultaneously steer development away from sensitive ecosystems.     

Hydrodynamic and ecological assessment of nearshore restoration: A modeling study

Along the Pacific Northwest coast, much of the estuarine habitat has been lost over the last century to agricultural land use, residential and commercial development, and transportation corridors. As a result, many of the ecological processes and functions have been disrupted. To protect and improve these coastal habitats that are vital to aquatic species, many projects are currently underway to restore estuarine and coastal ecosystems through dike breaches, setbacks, and removals. Understanding site-specific information on physical processes is critical for improving the success of such restoration actions. In this study, a three-dimensional hydrodynamic model was developed to simulate estuarine processes in the Stillaguamish River estuary, where restoration of a 160-acre parcel through dike setback has been proposed. The model was calibrated to observed tide, current, and salinity data for existing conditions and applied to simulate the hydrodynamic responses to two restoration alternatives. Model results were then combined with biophysical data to predict habitat responses within the restoration footprint. Results showed that the proposed dike removal would result in desired tidal flushing and conditions that would support four habitat types on the restoration footprint. At the estuary scale, restoration would substantially increase the proportion of area flushed with freshwater (<5 ppt) at flood tide. Potential implications of predicted changes in salinity and flow dynamics are discussed relative to the distribution of tidal marsh habitat.     

Locomotion modes of deep-sea cirrate octopods (Cephalopoda) based on observations from video recordings on the Mid-Atlantic Ridge

The behaviour of cirrate octopods of the genera Cirroteuthis and Grimpoteuthis in their natural habitat was studied using video recordings. Sequences were filmed during the French cruise “Faranaut”, from the manned submersible “Nautile” at depths between 2702 and 4527 m, in two zones in the Fifteen-Twenty Fracture Zone on the Mid-Atlantic Ridge. Four different modes of active locomotion, namely crawling, take-off, fin-swimming, and pumping, and one apparently passive mode of locomotion, umbrella-style drifting, were observed. Jet-propulsion, a characteristic mode of locomotion typically employed by cephalopods, was not observed in the cirrate octopods filmed, although breathing movements of the mantle to aerate the gills were assumed to generate some slight propulsion through the funnel. Fin-swimming was the mode of active locomotion most frequently observed. Neutral buoyancy was confirmed in one individual after capture. This buoyancy enables passive drifting in the umbrella-style attitude observed in Cirroteuthis spp., possibly using near-bottom ocean currents. Pumping, a mode of slow locomotion generated by peristaltic waves in the primary and intermediate webs, also observed in Cirroteuthis sp., is described here for the first time. The take-off mode of locomotion, a sudden, single contraction of the brachial crown and web, is also described; it was always followed by fin-swimming. No medusoid swimming of the type previously described for opisthoteuthid cirrates was observed. A flight response to the approach of or contact with a strange object, i.e. the submersible, using the crawling, take-off, or fin-swimming modes was observed. A ballooning response was observed in a high-stress situation when a C.magna individual was captured. Received: 27 November 1996 / Accepted: 9 December 1996