Whitcraft, C.R. and B.J. Grewell. 2011 online. Managing perennial pepperweed (Lepidium latifolium) in a seasonal wetland prior to restoration of tidal hydrology. Wetland Ecology and Management (available as pdf soon)

Whitcraft, C.R., B.J. Grewell, and P. Baye*. 2011 online. Estuarine vegetation at Rush Ranch, San Francisco Bay National Estuarine Research Reserve, California. San Francisco Estuary and Watershed Science (available as pdf soon) *all authors contributed equally

Whitcraft, C., L. Levin, D. Talley, and J. Crooks. 2008. Utilization of invasive tamarisk by salt marsh consumers. Oecologia. (abstract) (.pdf)

Whitcraft, C. R. & L. Levin. 2007. Regulation of benthic algal and animal communities by salt marsh plants: impact of shading. Ecology 88(4): 904–917. (abstract) (.pdf)

Whitcraft, C. R., D. Talley, J. Crooks, J. Boland, and J. Gaskin. 2007. Invasion of tamarisk (Tamarix spp.) in a southern California salt marsh. Biological Invasions 9(7): 875-879. (abstract) (.pdf)

Whitcraft, C.R. and L.F. Pierotti. Submitted. Trophic roles of an ephemeral seagrass, Ruppia maritima, in a southern California lagoon. 

Whitcraft, C., L. Levin, D. Talley, and J. Crooks. In prep. “Terrestrialization” of coastal wetland ecosystems by a riparian invader.

Levin, L.A., C. R. Whitcraft, P. Lamont, G. Cowie, and G. Mendoza. Accepted pending revision. Response of biota and bioturbation to oxygen gradients within the lower oxygen minimum zone: A high-resolution view of the Pakistan margin 700-1100 m. Deep Sea Research II: 56 (6-7): 449-471
(.pdf)

Gooday, A.J., L.A. Levin, A. Aranda da Silva, B.J. Bett, G.L. Cowie, J.D. Gage,  D.J. Hughes, R. Jeffreys, P.A. Lamont, K.A. Larkin, S.J. Murty, S. Schumacher, C. Whitcraft, and C. Woulds. 2009. Faunal responses to oxygen gradients on the Pakistan margin: a comparison of foraminifera, macrofauna and megafauna. Deep Sea Research II 56 (6-7): 488-502.
(.pdf)

Woulds, C., G. Cowie, L. Levin, H. Andersson, J. Middelburg, S. Vandewiele, P. Lamont, K. Larkin, A. Gooday, S. Schumacher, C. Whitcraft, R. Jeffreys, and M. Schwartz. 2007. The role of sea floor biological communities in sedimentary carbon cycling: oxygen and other controls. Limnology and Oceanography 52(4): 1698-1709. (abstract) (.pdf)

Collinetti, E., W. Miller, K. Lion, A. Arnwine, B. Wells, C. Whitcraft, G M. Ruiz. Smithsonian Environmental Research Center (SERC) Marine Invasion Research Laboratory - Results from the National Ballast Water Information Clearinghouse. http://massbay.mit.edu/resources/pdf/MarinePDF/2001/MBI2001abs2.pdf

Whitcraft, C., L. Levin, D. Talley, and J. Crooks. 2008. Utilization of invasive tamarisk by salt marsh consumers. Oecologia.

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, coleopteran 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.

Plant cover is a fundamental feature of many coastal marine and terrestrial systems and controls the structure of associated animal communities.  Both natural and human-mediated changes in plant cover influence abiotic sediment properties and thus have cascading impacts on the biotic community. Using clipping (structural) and light (shading) manipulations in two salt marsh vegetation zones (one dominated by Spartina foliosa and one by Salicornia virginica), we tested whether these plant species exert influence on abiotic environmental factors and examined the mechanisms by which these changes regulate thebiotic community. In an unshaded (plant and shade removal) treatment, marsh soils exhibited harsher physical properties, a microalgal community composition shift toward increased diatom dominance, and altered macrofaunal community composition with lower species richness, a larger proportion of insect larvae, and a smaller proportion of annelids, crustaceans, and oligochaetes compared to shaded (plant removal, shade mimic) and control treatment plots. Overall, the shaded treatment plots were similar to the controls. Plant cover removal also resulted in parallel shifts in microalgal and macrofaunal isotopic signatures of the most dynamic species. This suggests that animal responses are seen mainly among microalgae grazers and may be mediated by plant modification of microalgae. Results of these experiments demonstrate how light reduction by the vascular plant canopy can control salt marsh sediment communities in an arid climate. This research facilitates understanding of sequential consequences of changing salt marsh plant cover associated with climate or sea level change, habitat degradation, marsh restoration, or plant invasion.

Exotic plants have been demonstrated to be one of the greatest threats to wetlands, as they are capable of altering ecosystem-wide physical and biological properties.  One of the most problematic invaders in the western United States has been salt cedar, Tamarix spp., and the impacts of this species in riparian and desert ecosystems have been well-documented. Here we document large populations of tamarisk in the intertidal salt marshes of Tijuana River National Estuarine Research Reserve, a habitat not often considered vulnerable to invasion by tamarisk.  Initial research demonstrates that there are multiple species and hybrids of Tamarix invading the estuary and that the potential impact of tamarisk within this salt marsh is significant.  This highlights the need for managers and scientists to be aware of the problems associated with tamarisk invasion of coastal marine habitats and to take early and aggressive action to combat any incipient invasion.

13C tracer experiments were conducted at sites spanning the steep oxygen, organic matter, and biological community gradients across the Arabian Sea oxygen minimum zone, in order to quantify the role that benthic fauna play in the short-term processing of organic matter (OM) and to determine how this varies among different environments. Metazoan macrofauna and macrofauna-sized foraminiferans took up as much as 56 6 13 mg of added C m22 (685 mg C m22 added) over 2–5 d, and at some sites this uptake was similar in magnitude to bacterial uptake and/or total respiration. Bottom-water dissolved oxygen concentrations exerted a strong control over metazoan macrofaunal OM processing. At oxygen concentrations .7 mmol L21 (0.16 ml L21), metazoan macrofauna were able to take advantage of abundant OM and to dominate OM uptake, while OM processing at O2 concentrations of 5.0 mmol L21 (0.11 ml L21) was dominated instead by (macrofaunal) foraminiferans. This led us to propose the hypothesis that oxygen controls the relative dominance of metazoan macrofauna and foraminifera in a threshold manner, with the threshold lying between 5 and 7 mmol L21 (0.11 to 0.16 ml L21).  Large metazoan macrofaunal biomass and high natural concentrations of OM were also associated with rapid processing of fresh OM by the benthic community. Where they were present, the polychaete Linopherus sp. And the calcareous foraminiferan Uvigerina ex gr. semiornata, dominated the uptake of OM above and below, respectively, the proposed threshold concentrations of bottom-water oxygen.