Cothurnia limnoriae - NSCEP | US EPA - US Environmental ...

Nonindigenous insects were predominantly found in Hawaii (40 NIS), with only five and one
nonindigenous marine/estuarine insect reported from the NEP and NWP, respectively (Figure
54). Many of the nonindigenous insects in Hawaii occur in saline streams (Englund, 2002;
Carlton and Eldredge, 2009) and are members of families in which the juvenile stage typically
occurs in fresh water (e.g., dragonflies).
The Chordata are composed of two dramatically different groups - the tunicates, with a total of
48 NIS, and fishes (Actinopterygii), with a total of 66 NIS. Nonindigenous tunicates were most
numerous in Hawaii (29 NIS) and the NEP (23 NIS) with only 9 species found in the NWP
(Figure 56). With the fishes, the NWP contained the largest number of nonindigenous species
(34) compared to Hawaii (28) or the NEP (25) (Figure 57). However, the most of the
nonindigenous fish in the NWP were intentionally released into the wild or are maintained in
aquaculture facilities, and in many cases it is not known if they are established in the wild.
The numbers of nonindigenous mollusks were similar among the gastropods (57 NIS) and
bivalves (53 NIS). The number of nonindigenous bivalve species was similar across the NEP,
Hawaii, and NWP (Figure 44). One similarity across all three locations was that each contained
one or more introduced oyster species and wood boring Teredo species. The number of
nonindigenous gastropods was highest in the NEP (28) and similar in Hawaii (19) and the NWP
(20) (Figure 45).
The nonindigenous annelids primarily consisted of polychaetes (81 NIS), with a similar number
of invaders in the NEP and Hawaii (Figure 42). One pattern with the polychaete invaders is that
there are proportionally fewer species in the NWP that exclusively or primarily inhabit softbottom
sediments compared to fouling species or those associated with oysters and other biotic
substrates.
Spatial Patterns of Invasion
As mentioned, a total of 747 NIS have been reported from the 23 ecoregions analyzed. In terms
of the total number of invaders, the NEP and Hawaii have approximately equal numbers, 368
and 347 NIS respectively (Figures 24 and 26). In comparison, the NWP, with 208 NIS, has
substantially fewer invaders. With 73 NIS, the NCIP has the fewest reported invaders; however
there is limited information on the five ecoregions making up the NCIP. The pattern of the extent
of invasion by taxonomic group (Figures 25 and 27-58) generally follows the same pattern. Of
the 25 non-aggregated taxonomic groups (e.g., Isopoda and Amphipoda but not Arthropoda), the
NEP had the most or was tied for the most invaders with 15 taxonomic groups, while Hawaii had
the most or was tied with the most invaders for 9 taxonomic groups. The NWP had the most or
was tied with the most invaders with 5 taxonomic groups (Phaeophyceae, Chlorophyta,
Decapoda, Cirripedia, and Actinopterygii). As discussed above, the high numbers of invaders
with the decapods and fishes in the NWP were partially a result of the large proportion of
aquaculture and intentionally released species, many of which have an unknown population
status.
On an individual ecoregion basis, the Hawaii ecoregion is considerably more invaded than any
other ecoregion, with 347 NIS (Figure 24). The Northern California Ecoregion, with 277 NIS, is
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