Wood et al. : A comparison between warm-water fish assemblages of Narragansett Bay and Long Island Sound waters 
95 
Figure 4 
Multidimensional scaling plot of standardized, fourth-root transformed, fish abundance data by year 
(1987-2000) and location based on Bray-Curtis similarity. The two main groupings indicate that fish 
abundances in Narragansett Bay (RI) and Long Island Sound (LIS) were not similar to each other annu- 
ally. The line contours describe 45% similarity from the clustering algorithm. Note that the year 1993 
appears to be an outlier, lacking similarity to the Narragansett Bay or Long Island Sound populations. 
In addition, RI 97 seems equally similar to both the RI and the LIS groupings. 
ducted for the weeks of peak fish occurrence and the 
temperature of that week, as well as the week of 50% 
minimum and maximum temperature as determined 
by cumulative degree days and both were significant 
(r=0.67; P=0.01 and /-=0.67; P=0.01, respectively). 
Discussion 
Despite their brief seasonal appearance, warm-water 
fish species are an important part of the overall faunal 
assemblage in temperate estuaries worldwide. These 
summer visitors contribute significantly to the overall 
species diversity of temperate estuaries (Wallace et al., 
1984; Francis et al., 1999), increasing both food sources 
and overall productivity (Chapin et al., 2000; Cardinale 
et al., 2002). The majority of the warm-water species 
found in this study have been recorded in the study 
areas only as juveniles; however, it is an open question 
whether this will always be the case. Many warm-water 
species are highly adaptable, and may eventually be able 
to over-winter in temperate estuaries, becoming part 
of the resident species assemblage. An influx of these 
new residents could affect the ecosystem structure and 
function in these estuaries. 
The diversity and abundance of Narragansett Bay 
and Long Island Sound warm-water fish are increas- 
ing, apparently because of warming coastal waters. The 
species assemblages of both areas are similar. However, 
differences in both species presence and overall species 
abundance exist between the two data sets. For exam- 
ple, large schools of Atlantic moonfish were caught in 
a Narragansett Bay trawl survey in 1994, leading to a 
huge increase of overall catch abundance for that year. 
Schooling fishes, such as the Atlantic moonfish, caught 
during our study may influence the interpretation of 
the survey data. Another difference in species pres- 
ence was indicated by the presence of a species in only 
one of the two areas surveyed uring the years of this 
study (1987-2000). Species such as the inshore lizard- 
