I want to investigate the relationship between differences in coral physiological variables based on euclidean distances and seawater environmental variables using DISTLM and dbRDA in PRIMER, but I am not sure if this analysis is suitable given the lack of replication I have in my predictor variable (environmental) matrix.

I have attached an excel file illustrating the structure of my data set (the response and predictor variables). Briefly, I have a multivariate data set of measured physiological variables (e.g. lipid concentration, protein concentration, tissue biomass etc.) for corals collected from five different locations (A-E), where each site is very unique in its seawater physico-chemical parameters. I collected 12 corals per site (total of 60 samples). I have constructed a resemblance matrix of the physiological data in PRIMER based on Euclidean distances, and there is clear grouping of data points in the NMDS, which coincides with the different collection sites for each coral. I want to investigate the proportion of the observed variation in the multivariate data cloud that can be explained by the environmental characteristics of each collection site (e.g. mean annual sea surface temperature, seawater chlorophyll concentration, salinity etc.). However, the dataset of environmental variables does not have replication. i.e. for each site (A-E), I only have one value for mean annual sea surface temp, one value of salinity etc.

All of the case-study examples I have read about distance-based redundancy analysis in R or PRIMER have two resemblance matrices (predictor and response) both of which have replication. However, in my case, my response variables have replication (i.e. 12 samples per site), whereas my environmental variables do not have replication (i.e. one measurement per variable per site).

Can someone advise me whether or not dbRDA is suitable in this instance? If as I predict, it is not suitable, can you recommend a better approach? I am not an expert in multivariate statistics, but I want to make sure that the approach I take is sound.

Any and all advice is welcome. Thanks