LONG-TERM ENVIRONMENTAL MONITORING - SOME PERSPECTIVES FROM LAKES

As part of a workshop sponsored by the Sustainable Biosphere Initiativ e on Change and Trend Detection, we have reviewed some general conside rations pertinent to establishing long-term monitoring programs. A gen eral goal of most long-term monitoring is to assign causality and esta blish mechanisms for patterns in observed data. However, mechanistic i nference can be difficult in complex, often uncontrolled, natural syst ems. We present examples from three lakes representing (1) highly mani pulated, intensively monitored systems, (2) management situations wher e many simultaneous manipulations may be occurring, and (3) at-large s urveillance programs with no deliberate manipulations. We show that at one end of this continuum, in controlled, intensively monitored lakes , delayed and counterintuitive responses can make mechanistic inferenc e difficult. At the other end of the continuum, where no management or experimental manipulations are underway, it is still possible to asce rtain mechanism in the presence of apparently conflicting data, given sufficient information about the system. Management situations are oft en difficult to decipher; many simultaneous manipulations often confou nd mechanistic interpretations, although patterns in the data are read ily apparent.