Seventeen species of chaetognaths belonging to nine genera and three families were recognized from the samples collected in estuaries of Tamshui River and Kaoping River from February 2003 to November 2003. In Tamshui River estuary, eleven species belonging to eight genera and three families were recorded, with the mean abundance of 807 ¡Ó 1154 ind./100m3, while in Kaoping River estuary, fourteen species belonging to nine genera and three families were identified, with the mean abundance of 1601 ¡Ó 2796 ind./100m3. The three most dominant species in both estuaries were Flaccisagitta enflata, Aidanosagitta crassa and A. neglecta, and together they comprised ¡Ö95¢Mof the total chaetognaths. The abundance of chaetognaths showed apparent seasonal changes, higher abundance in February in Tamshui River estuary and in May in Kaoping River estuary. The abundance of chaetognaths showed no significant correlation with temperature in both estuaries, but displayed higher relationships to salinity and copepods. The body length¡]BL¡^ of Flaccisagitta enflata showed significant seasonal and spatial differences, with larger in both February and May in Tamshui River estuary but only in May in Kaoping River estuary. Aidanosagitta crassa showed significantly larger in BL in February than in other months in Tamshui River estuary, but it was not in Kaoping River estuary. The stage I of chaetognaths dominated in this study area and occupied ¡Ö80¢Mof the total count. Other stages mostly presented in February in Tamshui River estuary and in May in Kaoping River estuary. Only Fl. enflata was found to have gut content, all copepods, in February and May. The estimated daily predation impact on the standing stock of copepods ( by number ) was insignificant, only ¡Õ1¢H in both estuaries.

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The one-dimensional numerical model developed by Carl R. Goodwin is applied to the Siuslaw estuary. Vertical displacement, horizontal velocity and flow of the water as a function of time and distance from the mouth given by the model are compared with field observations taken under different water mixing conditions in the estuary. The model is considered adequate under well mixed and partially mixed conditions, and inadequate under strongly stratified conditions. Estimations of deviations between model predictions and field observations are presented. Nomograms are constructed from model predictions of amplification factors, high water time lags, maximum flood velocities, maximum ebb velocities, low water time lags, maximum flood flows, maximum ebb flows, high slack water time lags and low slack water time lags, as a function of river flow, ocean tidal range and river mile for a range of 0 to 6000 cubic feet per second (0 to 170 cubic meters per second) of river flow, and 1 to 11 feet (0.30 to 3.35 meters) of ocean tidal range. These nomograms are considered adequate for predictive purposes during well mixed and partially mixed conditions of the estuary waters. / Graduation date: 1975

The seasonal and spatial changes in species composition and abundance of copepods in relation to environment factors in both Tanshui and Kaoping estuaries were investigated in 2003. In total, 99 copepod species belonging to 8 genera and 3 families and 113 species belonging to 25 genera and 4 families were identified in the Tanshui and Kaoping estuaries, respectively; correspondingly each with the mean abundance of 1680 ¡Ó 403 inds/m3 and 3682 ¡Ó 1274 inds/m3. The species composition of copepods was apparently different between Tanshui and Kaoping estuaries. In the Tanshui estuary, the 6 most dominant copepods, Temora turbinata, Euterpina acutifrons, Canthocalanus pauper, Acrocalanus longicornis, Acrocalanus gibber, and Nannocalanus minor, were all marine species; among them, T. turbinata was the most abundant and contributed 11.9% to the total copepod count. While in the Kaoping estuary, many dominant species were freshwater dwellers, such as Pseudodiaptomus annandalei, Neodiaptomus schmackeri, Microcyclops tricolor, and Paracyclops fimbriatus. P. annandalei was the most abundant species and contributed 8.3% to the total copepods. The dominant marine species in the Kaoping estuary were Pseudodiaptomus marius, T. turbinata, Acartia omorii, Cosmocalanus darwini and Paracalanus parvus. The species composition and abundance of the copepods exhibited noticeable seasonal changes in both estuaries, particularly in the Kaoping estuary, probably related to the intensities of monsoon, rainfull and runoff of freshwater. In the Tanshui estuary, copepod assemblages were short of clear seasonal changes; the dominant species, Temora turbinata, Euterpina Acutifrons, and Canthocalanus pauper were found in all sampling months, with the peak abundance of these species as well as of the total copepods in May and lowest in November. In the Kaoping estuary, the peak abundance was found in February and lowest in August, while P. annandalei and Mongolodiaptomus birula were the most dominant species in these two months, respectively. The copepod (with the exception of Acrocalanus longicornis) abundance in the Tanshui estuary showed insignificant correlation with environmental factors, having significant and negative correlation with temperature. In the Kaoping estuary, on the other hand, most copepods were negatively and significantly correlated with both temperature and salinity.