title: Utilization of invasive tamarisk by salt marsh consumers.
abstract: Plant invasions of coastal wetlands are rapidly changing the structure and function of these systems globally. Alteration of litter dynamics represents one of the fundamental impacts of an invasive plant on salt marsh ecosystems. Tamarisk species (Tamarix spp.), which extensively invade terrestrial and riparian habitats, have been demonstrated to enter food webs in these ecosystems. However, the trophic impacts of the relatively new invasion of tamarisk into marine ecosystem have not been assessed. We evaluated the trophic consequences of invasion by tamarisk for detrital food chains in the Tijuana River National Estuarine Research Reserve salt marsh using litter dynamics techniques and stable isotope enrichment experiments. The observations of a short residence time for tamarisk combined with relatively low C:N values indicate that tamarisk is a relatively available and labile food source. With an isotopic (15N) enrichment of tamarisk, we demonstrated that numerous macroinvertebrate taxonomic and trophic groups, both within and on the sediment, utilized 15N derived from labeled tamarisk detritus. Infaunal invertebrate species that took up no or limited 15N from labeled tamarisk (A. californica, enchytraeid oligochaetes, coleoptera larvae) occurred in lower abundance in the tamarisk-invaded environment. In contrast, species that utilized significant 15N from the labeled tamarisk, such as psychodid insects, an exotic amphipod, and an oniscid isopod, either did not change or occurred in higher abundance. Our research supports the hypothesis that invasive species can alter the trophic structure of an environment through addition of detritus and can also potentially impact higher trophic levels by shifting dominance within the invertebrate community to species not widely consumed.
authors.affiliation: Integrative Oceanography Department, Scripps Institution of Oceanography, La Jolla, CA 92093-0218, USA. cwhitcra@csulb.edu
authors.forename: Christine R
authors.initials: CR
authors.lastname: Whitcraft
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Levin
authors.forename: Drew
authors.initials: D
authors.lastname: Talley
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Crooks
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003247:Conservation of Natural Resources; D005247:Feeding Behavior; D020387:Food Chain; D007448:Invertebrates / Q000378:metabolism* / Q000502:physiology; D008954:Models, Biological; D015999:Multivariate Analysis; D009587:Nitrogen Isotopes / Q000378:metabolism; D032363:Tamaricaceae; D053833:Wetlands
chemical_list: D009587:Nitrogen Isotopes
references.citation: Science. 1985 Mar 15;227(4692):1361-3
references.pmid: 17793771
references.citation: Science. 2004 Jun 11;304(5677):1629-33
references.pmid: 15192218
references.citation: Ecology. 2006 Feb;87(2):419-32
references.pmid: 16637367
references.citation: Ecology. 2007 Apr;88(4):904-17
references.pmid: 17536707
references.citation: Ecol Appl. 2006 Aug;16(4):1391-404
references.pmid: 16937806
references.citation: J Med Entomol. 1995 Nov;32(6):882-7
references.pmid: 8551514
references.citation: Oecologia. 1997 Apr;110(2):262-277
references.pmid: 28307434
references.citation: Oecologia. 1997 Jun;111(1):109-122
references.pmid: 28307495