Chapters 1 - U.S. Fish and Wildlife Service

Environmental Consequences
However, some research indicates that there may be indirect effects on the ecosystem as a result
of multiple applications of mosquito control products. These effects relate to disruptions in the
invertebrate food web that can affect non-target fauna (Hershey et al. 1998, Poulin et al. 2010).
For instance, the availability of prey for birds such as swallows could be adversely affected over
time. There is however limited research on this topic, therefore, the degree to which Refuge birds
could be impacted is not known.
Public Use
The effects to landbirds as a result of continuing the limited public use program currently
conducted on the Refuge would be similar to those described above for waterbirds. No significant
adverse impacts to landbirds are therefore anticipated.
5.4.1.3 Effects to Fish and other Marine Organisms
Wildlife and Habitat Management
Continuing to conduct wildlife and habitat activities related to trash and debris removal, invasive
plant control, culvert maintenance and periodic replacement, environmental contaminants
coordination, native upland plant restoration, species surveys, and predator management would
have limited potential for impacts to fish and marine organisms. Of the management activities
proposed under Alternative A, culvert maintenance/replacement and invasive plant control would
have the potential for adverse impacts to fish and other marine organisms if BMPs are not
implemented as part of these activities. To avoid any adverse effects to these species, activities
related to the inspection, cleaning, and/or replacement of culverts would include the
implementation of BMPs. Culverts are generally inspected on an annual basis and cleaned every
five to ten years, if needed. Replacement only occurs if there is significant evidence of corrosion.
To reduce the potential for impacts to fish and other marine organisms from these activities,
BMPs, as described in Section 5.2.1.6, would be implemented to minimize the introduction of
sediment into the Refuge’s wetland areas, reduce the potential for increased turbidity levels within
the water column, prevent general degradation of water quality, reduce the potential loss of fish
during construction, and avoid impacts to eelgrass habitat. Any impacts to eelgrass habitat would
be mitigated in accordance with the requirements of the Southern California Eelgrass Mitigation
Policy, adopted July 31, 1991.
Pest Management
As described in Section 5.4.1.1, invasive plant control on the Refuge currently involves mechanical
removal, as well as the application of herbicides. Glyphosate-based herbicides are post emergent,
systematic herbicides acceptable for use in wetland areas. If used in accordance with the product
label, these products pose no hazard to fish or other marine organisms. Specifically, terrestrial
formulations of these herbicides are only used in upland areas and a minimum buffer of 50 feet is
maintained between application areas and adjacent wetlands. Additionally, on this Refuge, aquatic
formulations of glyphosate-based herbicides are only used along the margins of wetland areas and
a minimum buffer of 25 feet is maintained between the application area and the adjacent wetland.
Surflan AS, which contains the active ingredient oryzalin, is toxic to fish and therefore is not
permitted for use in wetland areas. When used in accordance with label instructions and in
association with BMPs, this product is not expected to adversely affect fish or other marine
organisms.
Further, microbial larvicides and methoprene are used on the Refuge by the OCVCD to control
mosquitoes. When applied in accordance with label directions, microbial larvicides (Bti and Bs) are
not expected to pose a risk to fish or other marine organisms.
Draft Comprehensive Conservation Plan 5-41