Spatial Distribution Characteristics of Surface Tidal Currents in the Southwest of Taiwan Strait

This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.

Population dynamics of Philocheras trispinosus(Crangonidae)with abundance of other caridean shrimps(Crustacea:Decapoda)caught by beam trawl in the Southern Black Sea,Turkey

Objective:To determine growth and reproduction biology of Philocheras trispinosus(P.trispinosus)with abundance of other caridean shrimps caught by beam trawl in the Southern Black Sea.Methods:Samplings were carried out monthly with a beam trawl of 2 m length and 15 mm cod-end mesh size between December 2012 and November 2013.All individuals were sampled between 1 and 40+m water depth from 146 hauls.Results:A total of 550 P.trispinosus,618 Palaemon adspersus,12 Palaemon serratus,11 Philocheras fasciatus and 10 Crangon crangon were sampled during the study period.The crangonid shrimps started appearing during the winter and spring and the number of individuals increased to reach their highest value in mid-winter and mid-spring.The seasonal von Bertalanffy growth parameters for P.trispinosus were estimated as L_(∞)=29.3 mm total length,K=0.860/year,t_(0)=–0.900 year,C=0.180,and t_(s)=0.010.The start of the slow growth period was at the beginning of July(WP=0.510).Ovigerous females appeared in the sampling area between January and April.Size at sexual maturity was estimated as 25.69 mm total length.Conclusions:The results supported the distribution and abundance of caridean shrimp species from the study area and the population dynamics of the most abundant shrimp species,P.trispinosus.The current study can be answered as baseline data prior to management strategies to ensure sustainable conservation of the shrimp species.