SUMMARY The size and structure of an animal's brain is typically assumed to result from either natural or artificial selection pressures over generations. However, because a fish's brain grows continuously throughout life, it may be particularly responsive to the environmental conditions the fish experiences during development. Salmon are an ideal model system for studying these effects because natural habitats differ significantly from the hatchery environments in which these fish are frequently reared. For example, in the wild, salmon alevins (i.e. yolk-sac fry) are buried in the gravel, while hatchery environments lack this structural component. We show that the simple manipulation of adding stones to a standard rearing tank can dramatically alter the growth of specific brain structures in steelhead salmon alevins(Oncorhynchus mykiss). We found that alevins reared with stones grew brains with significantly larger cerebella than genetically similar fish reared in conventional tanks. This shift to a larger cerebellar size was, in turn, accompanied by changes in locomotory behaviors - behaviors that correlate strongly to the function of this brain region. We next show that hatchery fish reared in a more naturalistic setting in the wild had significantly larger brains than their lab-reared counterparts. However,relative cerebellar volumes were similar between wild-reared alevins and those reared in the complex treatment in the laboratory. Together our results indicate that, within the first three weeks of life, variation in rearing environment can result in brain differences that are commonly attributed to generations of selection. These results highlight the need to consider enrichment strategies when designing captive rearing facilities for both conservation and laboratory use.

Recent studies suggest that hatchery-reared fish can have smaller brain-to-body size ratios than wild fish. It is unclear, however, whether these differences are due to artificial selection or instead reflect differences in rearing environment during development. Here we explore how rearing conditions influence the development of two forebrain structures, the olfactory bulb and the telencephalon, in juvenile Chinook salmon (Oncorhynchus tshawytscha) spawned from wild-caught adults. First, we compared the sizes of the olfactory bulb and telencephalon between salmon reared in a wild stream vs. a conventional hatchery. We next compared the sizes of forebrain structures between fish reared in an enriched NATURES hatchery and fish reared in a conventional hatchery. All fish were size-matched and from the same genetic cohort. We found that olfactory bulb and telencephalon volumes relative to body size were significantly larger in wild fish compared to hatchery-reared fish. However, we found no differences between fish reared in enriched and conventional hatchery treatments. Our results suggest that significant differences in the volume of the olfactory bulb and telencephalon between hatchery and wild-reared fish can occur within a single generation.

Surface deposit feeders live in an environment in which nutritional states change rapidly due to flux of surface material. This project addressed the question of foraging choice by a common spionid deposit feeder, Streblospio benedicti. Individuals of S. benedicti were offered both organically enriched sediment and unaltered sediment simultaneously as feeding choices. Three organic conditions along with the worms' natural sediment were employed in the choice experiments. The natural sediment had an organic content of 1.5%. Organic enrichments were prepared by adding 0, 2, 4, or 8% by weight of an organically enriched substance to natural sediment, which resulted in final organic contents of 1.5, 4.6, 6.9, and 12.1% organic matter respectively. The worms were videotaped for 30 min each. Feeding was measured as time spent collecting particles on one or the other of the sediment additions. With increasing organic enrichment the worms consistently chose to forage on the enriched sediments and concomitantly reduced their likelihood of major tissue loss by reducing their degree of exposure while foraging. On unenriched sediments worms enlarged their foraging area by increasing their exposure of body segments as well as tentacles, thus also increasing their predation risk. The switches in foraging locale and degree of pre-ingestion sorting with enrichment indicate selectivity on a small spatial scale.

SynopsisThe goal of this project was to determine if bat rays, Myliobatis californica, display oriented movements and are thus a viable model species for the further study of geomagnetic topotaxis in elasmobranches. We tracked one male and three female rays during September 1998 and August and September 2001 in Tomales Bay, California. The rays exhibited two modes of travel: (1) rapid and highly directional movements in a straight line along the length of the bay and (2) slow and non-directional movements within small areas. Directional movements were defined as point-to-point vectors in the paths of the bat rays that were oriented in similar directions, and the distribution of these was clustered rather than dispersed and uniform. Mean rates of movement during directional swimming approached 0.5 m s )1 . In contrast, vectors in the path of bat rays were at times oriented in varying directions, and a distribution of these was widely dispersed as we would expect if the rays were moving randomly. These were defined as non-directional movements. Oriented straight-line swimming is consistent with the species either being able to orient to the bathymetry of the bay or possessing a compass and (or) piloting sense.

Increases in extreme weather events have caused extensive flooding across the United States. In response, federal, state, and local governments have broadened their flood mitigation strategies to include acquisition and demolition of flood-damaged homes (“buyouts”). Little work has documented or analyzed the range of strategies for funding buyouts. Federal programs provide the bulk of funding, but these programs are often slow. Also, state and local governments struggle to meet cost-match requirements. We present and analyze a nationwide census of buyout funding programs (n = 34), which draw on five primary funding mechanisms. We find that state and local governments are using a range of traditional and innovative financial mechanisms, including municipal/green bonds, revolving loan funds, local option sales taxes, and stormwater utility fees, as viable tools for funding buyouts. These tools may promote more autonomy from federal government mitigation programs, and ultimately, faster buyout processes.