It is evident from the above that proper sampHng of the marine environment 

 is an important step in monitoring and impact assessment. For example, even 

 though analytical methods for estimating certain environmental parameters 

 may be highly accurate and precise, if the sample being analyzed is not 

 representative, the data resulting from the analysis is relatively worthless. 



A samphng program for any environmental monitoring or baseline study 

 must consider expUcitly the following items: a) the number of samples 

 required; b) samphng frequency; c) parameters to be measured; and 

 d) sampling locations. These items are premised on some accepted definition of 

 the level of perturbation or impact which is ecologically significant. It is 

 recognized that a complete environmental assessment program encompasses a 

 relatively comprehensive characterization (physical, chemical, biological) of a 

 system, and includes determination of the potential impacts of pollutants or 

 environmental changes on human health and ecological systems. Lucas (8) and 

 Eberhart (5) have provided a review of some of the difficulties in assessing 

 impacts and have proposed some models as bases for taking and analyzing 

 environmental data. It is our belief that programs with more hmited objectives 

 of characterizing existing conditions or identifying previously defined impacts 

 or changes can be developed as subsets of larger environmental assessment and 

 monitoring programs. It is our objective to briefly describe some aspects of the 

 design and analysis of such experiments to answer some specific questions on 

 sampling with particular reference to ichthyoplankton. 



Most biotic elements of the environment are highly variable and 

 everchanging. They must be sampled with sufficient intensity to determine the 

 course of such changes in time and space. Empirical evidence to date 

 concerning ichthyoplankton, as well as juvenile and adult fishes, suggests that 

 intensive sampling over time and space may be necessary to detect reasonable 

 changes in these populations. 



STATISTICAL METHODOLOGY 



There have been two general kinds of statistical methodology applied to 

 environmental impact analysis and monitoring. They are hnear model analysis 

 and time series analysis. 



Time series analysis will not be considered in detail in this report. However, 

 it wiU be briefly mentioned. In time-series analysis, the correlation of a 

 response variable to past observations is taken into account in the formulation 

 of a statistical model. Statistical time-series analysis has been treated in several 

 excellent books including: Anderson (1), Box and Jenkins (2), and Nelson (9). 

 The treatment of the methodology of time-series is comprehensive in these 

 references, and the reader is referred to them for details. Our limited 



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