Figure 1.
Location and benthoscape patch structure of the two study areas in Long Island Sound, USA.
The approximate geographic centers of the study sites are at 41.091772°N, 73.01239°W, and 41.027571°N, 73.282928°W for the Milford and Norwalk sites, respectively. The blue boxes are locations of sampling blocks in different patches.
Figure 2.
Hierarchical, additive partitioning scheme indicating the spatial scales at which β-diversity components were calculated.
Total diversity at a specific sampling time, γ, is calculated as γ = α1 (within sampling blocks)+β1 (among locations/sampling blocks within patches)+β2 (among patches)+β3 (among locations with benthoscapes)+β4 (among benthoscapes ). The same hierarchical structure was use for multiplicative partitioning, but in this case γ = α1×β1×β2×β3×β4.
Figure 3.
Results of weighted and unweighted additive partitions of species richness across two benthoscapes in Long Island Sound.
Randomization test results are given to the right of the figures. “> ” indicates significantly (p<0.05) larger contributions than expected from random to the diversity component at that scale, “< expected indicates significantly smaller contribution; NS indicated not significantly different (p>0.10) from random, m indicates marginally significant (0.05>p<0.10).
Figure 4.
Differences in the mean (+95% confidence interval) temporal contribution of diversity components to species richness in Long Island Sound.
Spatial scale associated with each diversity component is given in Fig. 2. Although the mean values are presented for the unweighted partition, a Kruskal-Wallis test was used to test for differences in medians. Lowercase letters show results of post-hoc tests, diversity components sharing the same letters were not significantly different (p<0.05).
Figure 5.
Temporal fluctuations in β turnover diversity at different spatial scales in Long Island Sound, based on multiplicative partitioning.
Spatial scales associated with each β-diversity component are given in Fig. 2. Weighted and unweighted refer to species richness.
Table 1.
Results of significance tests of multiplicative β-diversity components from partitioning analyses using individual-based randomizations.
Figure 6.
Temporal fluctuations in the mean number of shared taxa (upper) and the number of taxa in several different categories of rarity (lower) in Long Island Sound.
Rarity categories are defined in text. The upper graph also shows the fluctuation in the total number of taxa found at each sampling time.
Table 2.
Frequency of rarity of Long Island Sound macrofauna during the 1995–1996 study period, and the taxonomic and functional characteristics of taxa that were not found seven of the eight sampling periods.