Summary
Understanding the drift dynamics of pallid sturgeon (Scaphirhynchus albus) early life intervals is critical to evaluating damming effects on sturgeons. However, studying dispersal behavior is difficult in rivers. In stream tanks, we studied the effect of velocity on dispersal and holding ability, estimated swimming height, and used the data to estimate drift distance of pallid sturgeon. Dispersal was by days 0–10 embryos until fish developed into larvae on day 11 after 200 CTU (daily cumulative temperature units). Embryos in tanks with a mean channel velocity of 30.1 cm s−1 and a side eddy could not hold position in the eddy, so current controlled dispersal. Late embryos (days 6–10 fish) dispersed more passes per hour than early embryos (days 0–5 fish) and held position in side eddies when channel velocities were 17.3 cm s−1 or 21.1 cm s−1. Day and night swim‐up and drift by embryos is an effective adaptation to disperse fish in channel flow and return fish from side eddies to the channel. Early embryos swam <0.50 cm above the bottom and late embryos swam higher (mean, 90 cm). A passive drift model using a near bottom velocity of 32 cm s−1 predicted that embryos dispersing for 11 days in channel flow would travel 304 km. Embryos spawned at Fort Peck Dam, Missouri River, must stop dispersal in <330 km or enter Lake Sakakawea, where survival is likely poor. The model suggests there may be a mismatch between embryo dispersal distance and location of suitable rearing habitat. This situation may be common for pallid sturgeon in dammed rivers.
Understanding sea-level processes, such as ocean tides, storm surges, tsunamis, El Niño and rises caused by climate change, is key to planning effective coastal defence. Building on David Pugh's classic book Tides, Surges and Mean Sea-Level, this substantially expanded, full-colour book now incorporates major recent technological advances in the areas of satellite altimetry and other geodetic techniques (particularly GPS), tsunami science, measurement of mean sea level and analyses of extreme sea levels. The authors discuss how each surveying and measuring technique complements others in providing an understanding of present-day sea-level change and more reliable forecasts of future changes. Giving the how and the why of sea-level change on timescales from hours to centuries, this authoritative and exciting book is ideal for graduate students and researchers in oceanography, marine engineering, geodesy, marine geology, marine biology and climatology. It will also be of key interest to coastal engineers and governmental policy-makers.
[1] Observations of sea level at Port Arthur, Tasmania, southeastern Australia, based on a two-year record made in 1841 -1842, a three-year record made in 1999 -2002, and intermediate observations made in 1875 -1905, 1888 and 1972, indicate an average rate of sea level rise, relative to the land, of 0.8 ± 0.2 mm/year over the period 1841 to 2002. When combined with estimates of land uplift, this yields an estimate of average sea level rise due to an increase in the volume of the oceans of 1.0 ± 0.3 mm/year, over the same period. These results are at the lower end of the recent estimate by the Intergovernmental Panel on Climate Change of global average rise for the 20th century. They provide an important contribution to our knowledge of past sea level rise in a region (the Southern Hemisphere) where there is a dearth of other such data.
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