This paper presents a characterisation of the most significant environmental influences on plastochrone interval variation for Zostera marina L. in Punta Banda estuary B.C. Mexico. Data were collected from April 1998 to December 2001. Using correlation and principal component analysis, we found that the combination of sea surface temperature, light radiation and dissolved nutrients explains the observed variability consistently. Sea surface temperature was found to be the dominant environmental influence (r=0.89, p<0.05). Using empirical modelling procedures we also found that there is a direct causal relationship between sea surface temperature and plastochrone interval values. In conclusion, from both a quantitative and a qualitative perspective sea surface temperature was found to summarise the relevant environmental forcing. Moreover, ENSO events control plastochrone interval variation throughout alterations in abiotic variables determining the observed dynamics.