Notonectid dispersal data

This data was collected in the field at the Koffler Scientific Reserve in Ontario, Canada. Column headings: round - the number of notonectids in each tank were counted twice in two rounds (first and last rounds); tank# - there were 30 tanks in the experiment, each tank appears twice in the datasheet, once in the first round once in the last round; block - the 30 tanks were split into three time blocks (1, 2, and 3); fish treatment - tanks received no fish (no) or one caged fish (yes); notonectid density - categorical density treatment (low, medium, or high); initial #notonectids - number of notonectids initially placed in tank, corresponds to notonectid density treatment (low = 19, medium = 38, high = 60); total #dead notonectids - total number of notonectids found dead in given tank as of the given round; remaining #notonectids - total number of living notonectids found in given tank in given round

本数据集采集自加拿大安大略省科弗勒科学保护区（Koffler Scientific Reserve）的野外现场。
各字段表头含义如下：
1. 轮次（round）：每个水箱内的仰泳蝽（notonectid）数量会在两轮实验中各完成一次计数，分别对应首轮与末轮；
2. 水箱编号（tank#）：本实验共设置30个实验水箱，数据表中每个水箱将出现两次，分别对应首轮与末轮的计数记录；
3. 区块（block）：30个实验水箱被划分为3个时间区块，编号依次为1、2、3；
4. 鱼类处理组（fish treatment）：实验水箱分为两类处理方式，一组未投放鱼类（标注为no），另一组投放1只笼养鱼类（标注为yes）；
5. 仰泳蝽密度处理组（notonectid density）：设置了3个类别化密度水平，分别为低、中、高；
6. 初始仰泳蝽数量（initial #notonectids）：初始投放至对应实验水箱的仰泳蝽个体总数，与密度处理组一一对应：低密度组为19只，中密度组为38只，高密度组为60只；
7. 累计死亡仰泳蝽数量（total #dead notonectids）：截至对应轮次，在指定实验水箱中发现的仰泳蝽死亡个体总数；
8. 存活仰泳蝽数量（remaining #notonectids）：对应轮次中在指定实验水箱内检测到的仰泳蝽存活个体总数。