was found on less than half of the sample days. Another amphipod, A. 
virginiana, was found even less frequently, Both amphipods were less abundant 
following nourishment, but the actual magnitude of the nourishment effect was 
difficult to evaluate due to their generally sporadic appearance and low 
numbers. 
Other organisms ‘encountered (in decreasing order of importance) included 
the polychaete, W. pteta; ghost crab, 0. quadrata (megalops and young adults); 
the idoteid isopod, Chtrtdotea coeca; the albuneid crab, Albunea gtbbesit; and 
unidentified decapod larvae. Although these animals never formed an important 
component of the biomass, they are mentioned here because of the inordinate 
effect their presence or absence had on some measures of community structure. 
Both the Shannon—-Weaver and Pielou Indexes are known to respond significantly 
to the presence or absence of a single category (species) when the number of 
categories (species) is low. None of these animals had been found on any 
nourished section of beach by the end of this study. 
6. Statistical Results. 
The population densities for F. talpotda, Donax spp., and H. canadensis 
were the only data suitable for Analysis of Variance (ANOVA); ANOVA requires a 
large sample size and parametric data (Zar, 1974). 
A nested analysis of variance was performed with the following results: 
(a) There was no significant difference between transects of a 
single beach on any given sample date. Thus, individual transects on the 
same beach could be treated as replicates of one another on any given 
sample date. 
(b) There was no significant difference between most consecutive 
sample dates on a particular beach. 
(c) There was a significant difference between tidal zones on the 
beach. 
(d) There was a significant difference on each beach between widely 
separated sample dates. 
(e) The comparison beach and the nourished beach had significantly 
different population densities both before and after nourishment. 
(f) There was a significant difference between population densities 
at the nourished beach before, during, and after nourishment. 
7. Community Relationships. 
a. Measures of Community Structure. Parametric statistics are not in 
order when comparing individual measures of diversity (Fig. 28), equitability 
(Fig. 29), species richness (Fig. 30), and dominance (Fig. 31), because these 
measures are only ratios and not from a normally distributed data population 
(Zar, 1974). There are ways to compare a single index value for one date to 
another value on another date; however, when values are as different as they 
are in this study, a graphic analysis is sufficient. 
48 
