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The vegetated intertidal zone has long been acknowledged as an important habitat for fish, but our understanding of the dynamics of intertidal migrations by these fish is limited. Using in situ video recordings, we examined fish movements into and out of the waterward margin of a fringing mangrove forest during spring tides at 27 haphazardly chosen sites throughout the Rookery Bay National Estuarine Research Reserve, Florida. Our results indicate that fish respond to tide stage in a species-specific manner. Based on the changes in relative abundance throughout the tide cycle, we identified 4 general intertidal migration patterns: (1) tide-level proportionate, with greatest abundance during high tide; (2) flood-and ebb-tide concentrated, with lowest abundance during high tide; (3) peak abundance at ebb and low tide; and (4) depth-limited but tidally independent. Given that the distribution of the fish within the intertidal zone was heterogeneous, we suggest that the placement of sampling gear within the intertidal zone and the timing of samples within the tide cycle can greatly influence the species composition of fish inventories.KEY WORDS: Fish · Tidal migration · Intertidal · Mangrove · Video · Sampling 370: 207-219, 2008 Our knowledge of the habitat use and dynamics of intertidal migrations has been limited by the logistic difficulties inherent to sampling mobile fauna in structurally complex aquatic habitats (see review by Rozas & Minello 1997). Such sampling is often laborintensive, may require habitat alteration (e.g. removal of vegetation) for the placement of sampling gear, and commonly relies on the ebbing tide to concentrate targeted species for collection. These challenges limit both spatial and temporal sampling replication, and largely prohibit in situ sequential sampling designs that are ideally suited for the study of the within-tide movements of intertidal migrants (Gibson 2003). Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerIn studies of nekton associated with mangrove habitats, the sampling period, when reported, has often been restricted to a single stage of the tide cycle (usually high tide), or if sampling was conducted over multiple tide stages, results have been reported as a cumulative total of individuals captured without mention of within-tide dynamics (Table 1). Quantitative sampling in the mangrove intertidal zone (sensu Rozas & Minello 1997) using enclosure gear has been, to our knowledge, restricted to high tide (Table 1). Passive sampling gear (e.g. fyke nets and block nets, Table 1) that collects fish from generally undefined areas of the intertidal zone as they are drained is positioned at high tide or late flood tide. In each of these instances, the usually implicit, and untested, assumption upon which the sampling designs were based was that most fish swim into the mangrove habitat with the flood tide and depart the intertidal zone as it is drained during the ebb. This assumption is revealed when these studies are in...

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The Johnson Creek Landslide is a translational slide in seaward-dipping Miocene siltstone and sandstone (Astoria Formation) and an overlying Quaternary marine terrace deposit. The basal slide plane slopes sub-parallel to the dip of the Miocene rocks, except beneath the back-tilted toe block, where it slopes inland. Rainfall events raise pore-water pressure in the basal shear zone in the form of pulses of water pressure traveling laterally from the headwall graben down the axis of the slide at rates of 1-6 m/hr. Infiltration of meteoric water and vertical pressure transmission through the unsaturated zone has been measured at ,50 mm/hr. Infiltration and vertical pressure transmission were too slow to directly raise head at the basal shear zone prior to landslide movement. Only at the headwall graben was the saturated zone shallow enough for rainfall events to trigger lateral pulses of water pressure through the saturated zone. When pressure levels in the basal shear zone exceeded thresholds defined in this paper, the slide began slow, creeping movement as an intact block. As pressures exceeded thresholds for movement in more of the slide mass, movement accelerated, and differential displacement between internal slide blocks became more pronounced. Rainfall-induced pore-pressure waves are probably a common landslide trigger wherever effective hydraulic conductivity is high and the saturated zone is located near the surface in some part of a slide. An ancillary finding is apparently greater accuracy of grouted piezometers relative to those in sand packs for measurement of pore pressures at the installed depth.

Cover. The photograph shows terrain and vegetation in the vicinity of the monitoring site in Portland's West Hills, Oregon. The camera was facing northeast and located about 50-meters southeast of the hydrologic monitoring site. The solar panel and a rain gage can be seen in the foreground. The treeless area is a scar from a recent landslide; the zone of depression was filled with gravel to mitigate the disturbed topography. For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit https://www.usgs.gov or call 1-888-ASK-USGS. Results of Hydrologic Monitoring of aFor an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as°F = (1.8 × °C) + 32.Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as°C = (°F -32) / 1.8. DatumVertical coordinates are referenced to the North American Vertical Datum of 1988 (NAVD 88).Altitude, as used in this report, refers to distance above the vertical datum.Horizontal coordinate information is referenced to the Universal Transverse Mercator, Zone 10, meters. Results of Hydrologic AbstractThe West Hills of Portland, in the southern Tualatin Mountains, trend northwest along the west side of Portland, Oregon. These silt-mantled mountains receive significant wet-season precipitation and are prone to sliding during wet conditions, occasionally resulting in property damage or casualties. In an effort to develop a baseline for interpretive analysis of the groundwater response to rainfall, an automated monitoring system was installed in 2006 to measure rainfall, pore-water pressure, soil suction, soil-water potential, and volumetric water content at 15-minute intervals. The data show a cyclical pattern of groundwater and moisture content levels-wet from October to May and dry between June and September. Saturated soil conditions tend to last throughout the wet season. These data show the hydrologic response of the monitored area to rainfall and provide insight into the dynamics of rainfall-initiated landsliding. This report details the monitoring methods and presents data

L L a andslides threaten lives and property in every State in the Nation. To reduce the risk from active landslides, the U.S. Geological Survey (USGS) develops and uses real-time landslide monitoring systems. Monitoring can detect early indications of rapid, catastrophic movement. Up-to-the-minute or real-time monitoring provides immediate notification of landslide activity, potentially saving lives and property. Continuous information from real-time monitoring also provides a better understanding of landslide behavior, enabling engineers to create more effective designs for halting landslide movement.

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