Movement of Tidal Shrimps in Isolation

Keywords: periodicities, non-parametric trend

Description

Tidal shrimps from the Brisbane River move up and down the tidal area (harbour pylon for example) in accordance with the movement of the tides. In this experiment shrimps were removed from their natural environment and isolated from environmental stimulae which would allow them to measure time. Their vertical position on an inclined slope was recorded every half hour starting 20 hours after removal and continuing for one week. Also recorded is the actual tide height during the same period, and six other measures of the shrimps' activity.


	Variable		Description

	Time		Hours since isolation
	Vertical		Vertical displacement from original position
	Y2 - Y7		Other activity measurements
	Tide		Actual tide height

Download

Data file (tab-delimited text)

Source

Yong Yuan, Department of Biology, University of Queensland.

Analysis

The data need to be detrended non-parametrically, and then searched for periodicities. The periodic behaviour of the shrimps' movement gradually breaks up over the week.

Time series plot of vertical movements (10184 bytes)