Cheng-Han Wu

Effects of food and light on naupliar swimming behavior of Apocyclops royi and Pseudodiaptomus annandalei (Crustacea, Copepoda)

We examined the effects of food and light on the swimming behavior of nauplii of the cyclopoid Apocyclops royi (Lindberg, 1940) (Copepoda: Cyclopoida) and the calanoid Pseudodiaptomus annandalei Sewell, 1919 (Copepoda: Calanoida). Several behavioral parameters such as swimming patterns, speed, and trajectories exhibited distinct ontogenetic differences between the two species. When algae Isochrysis galbana (Haptophyta: Isochrysidales) were offered as food to the nauplii of A. royi, they showed fast circle swimming behavior, while nauplii of P. annandalei never exhibited such behavior, neither with, nor without algae. The different behavioral patterns between the nauplii of both species suggest they both have different foraging strategies in detecting and capturing food.

Data-oriented analyses of ciliate foraging behaviors

Optimal foraging theory states that natural selection makes foragers efficient food harvesters and maximizing a colony’s energy intake. This study presumed that the ciliates foraging trajectories follow optimal foraging theory, verified the presumption and discover specific rules and patterns hidden in the ciliate’s trajectories data using methodologies of statistical, cluster analyses, and decision tree analysis. This study examined the foraging behaviors of ciliates by video recordings and quantitative analyses of movement trajectories under four nourishment conditions (low, medium, high, and highest concentrations). Similar biological studies adopt statistical analyses to certain locomotion indices to determine the responses of plankton to various aquatic environments. In addition to statistical analyses, cluster analysis was used in this study to confirm the observations of the statistical analyses. The statistical analysis and cluster analysis results in this study revealed two distinct groups of trajectories or behaviors, which matched the optimal foraging theory. Decision tree analysis was then applied to acquire objective information regarding foraging behaviors, and further detailed the foraging behaviors with explicit classification rules using locomotion indices. The production rules can play an alternative role to assess the sustainability of an aquatic environment in terms of algae concentration.

Hydroids (Cnidaria, Hydrozoa) from marine environments in Taiwan

BackgroundHydroids were identified from extensive surveys of benthos, and especially from worm tubes, in the Danshuei River estuary (DRE), in the northeast Taiwan Strait (NETS), and on a reef in Nanwan Bay (NWB), Taiwan.ResultsA total of 33 species (12 of them identified to generic and 1 to family rank only), referable to 22 genera, 12 families, and 2 orders, were distinguished. The majority of them were referable to order Leptothecata (84.8%) with the remainder being assigned to order Anthoathecata (15.2%). The only species found at NETS was Monoserius pennarius (Linnaeus, 1758). Plumularia habereri (Stechow, 1909) was recorded at both DRE and NWB. The known range of Dynamena nanshaensis (Tang, 1991), recorded for the second time, is extended further north. Six species (Aglaophenia latecarinata, Plumularia floridana, Diphasia palmata, Dynamena brevis, Dynamena obliqua, Synthecium elegans) are recorded for the first time in waters adjacent to the Chinese mainland.ConclusionsSpecies composition and abundances varied considerably from one environment to another and especially between DRE and NWB. This study provides the first taxonomic account of the hydroid fauna inhabiting the eastern Taiwan Strait region.