1. Chlorophyll a concentration at three sampling points of a study coastal location. (The distance between sampling locations from coast varies between 10 - 25 km).
2. Chlorophyll a concentration taken on one day of different months in a year but one season.
(For instance, for year 2002 taken on 12-3-2002 and for year 2003 taken on 14-2-2003)
3. Chlorophyll a measured at 3 depth levels.
If data availability is in above mentioned manner, can we prepare annual time series for the study location? how?
So, it means that you have one chlorophyll measurement per month and only for one season? How long the measurements were carried out? How many years? May be you can't create an annual trend, but you can study the seasonal trend of chlorophyll and know how it changes over different years. I think that it will be interesting too.
Dear Nitish,
Well, first of all I would like to state that chlorophyll content is rather tricky to measure as it varies a lot across time, environments, species, genotypes and even within one plant!
My colleagues and I investigated leaf chlorophyll content in Jatropha curcas measuring chlorophyll content of many genotypes planted at different sites on different time points of a season. We found high differences between sites and time points (combination of site x time point defined as one environment) as well as between genotypes. (In a preliminary test we found high differences between leaves within one plant as well!)
You may have a look on our publication entitled "Genetic variation in leaf chlorophyll content of Jatropha curcas L." (Senger et al., 2014).
To display an annual trend, you need to measure chlorophyll a at several time points at each location. To my point of view, the time points don´t need to be equal for all locations or years (i.e. you don´t need to measure all locations at the same day per year), if you define the environment as a combination of location and time point, because anyway there are different environmental conditions at different locations for the same day (e.g. there was rain on one day at one location, but not at another location).
Regards, Elisa
@Silvia Illuminati : Thank you. I have it for 5 years but there is a data gap not consecutive years. As you said i can look in to seasonal annual trend. But how do i construct the trend? for instance, Do i have to take of mean chlorophyll a of 3 water sampling locations taken on 12-3-2003 o and represent it as chlorophyll a value for March (or season name) 2003 in the trend for the study location? Will it be right?
@Elisa Senger: Thank you. I am looking at representing annual trend for chlorophyll a values measured at coastal waters. I agree with your point "environment as a combination of location and time point with respect to measurements". So my confusion is how to proceed in representing trend for data collected at 3 sampling locations in one season each year (but not same month of season each year)?
Regards,
Nitish
Hi Nitish,
Chlorophyll a in coastal waters is verry variable in time (and often from day to day , or tide to tide). Your sampling interval is, in my own opinion, rather limited. For instance, in my case for a small estuary for one year sampling during ice-free months, the minimum sampling protocol was 7 sampling stations, sampled bi-weekly, in triplicatas, for 7 months and we size fractionned as well.
Basically I think one season each year is probably not sufficiant to have good statistical confidence in the data.
Regards,
Remi
I would recommend Cloern and Jassby's 'wq' package in R for data analysis of chlorophyll a seasonal and interannual patterns.
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