The bottlenose dolphin Tursiops truncatus foraging around a fish farm：Effects of prey abundance on dolphins＇ behavior

The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied.The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond,individually and as groups,to the relative abundance of prey around a fish farm.Detailed views of dolphins＇ behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data.A total of 2150 dive intervals were analyzed,corresponding to 342 focal samples,lasting over 34 hours.Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds.This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area.This study＇s results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding,dolphins did not modify dive duration.Additionally,underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities.Thus,bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey.When top predators display behavioral responses to activities not directed at them,the task of studying all possible effects of human activities can become even more challenging.     

黔产野生鱼腥草挥发油成分分析

对黔产野生鱼腥草（Ｈｏｕｔｔｕｙｎｉａ ｃｏｒｄａｔａ Ｔｈｕｎｂ）采取水蒸汽蒸馏和石油醚萃取的两种方法提取精油和净油。用ＧＣ／ＭＳ进行定性、定量分析,鉴定了其中４８种成分。比较两种提取方法的分析结果,发现净油中抗菌有效成分鱼腥草素（ｈｏｕｔｔｕｙｎｉｎｕｍ）的含量明显高于精油中的含量。除高沸点的脂肪酸酯外,两者其它化学成分无明显差异。