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2004
Moseman, SM, Levin LA, Currin C, Forder C.  2004.  Colonization, succession, and nutrition of macrobenthic assemblages in a restored wetland at Tijuana Estuary, California. Estuarine Coastal and Shelf Science. 60:755-770.   10.1016/j.ecss.2004.03.013   AbstractWebsite

Modes of colonization, the successional trajectory, and trophic recovery of a macrofaunal community were analyzed over 19 months in the Friendship marsh, a 20-acre restored wetland in Tijuana Estuary, California. Traditional techniques for quantifying macrofaunal communities were combined with emerging stable isotopic approaches for evaluation of trophic recovery, making comparisons with a nearby natural Spartina foliosa habitat. Life history-based predictions successfully identified major colonization modes, although most taxa employed a variety of tactics for colonizing the restored marsh. The presence of S.foliosa did not seem to affect macrofaunal colonization or succession at the scale of this study. However, soil organic matter content in the restored marsh was positively correlated with insect densities, and high initial salinities may have limited the success of early colonists. Total macrofaunal densities recovered to natural marsh levels after 14 months and diversity, measured as species richness and the Shannon index (H'), was comparable to the natural marsh by 19 months. Some compositional disparities between the natural and created communities persisted after 19 months, including lower percentages of surface-feeding polychaetes (Polydora spp.) and higher percentages of dipteran insects and turbellarians in the Friendship marsh. As surficial structural similarity of infaunal communities between the Friendship and natural habitat was achieved, isotopic analyses revealed a simultaneous trajectory towards recovery of trophic structure. Enriched delta(13)C signatures of benthic microalgae and infauna, observed in the restored marsh shortly after establishment compared to natural Spartina habitat, recovered after 19 months. However, the depletion in delta(15)N signatures of macrofauna in the Friendship marsh indicated consumption of microalgae, particularly nitrogen-fixing cyanobacteria, while macroalgae and Spartina made a larger contribution to macrofaunal diets in the natural habitat. Future successional studies must continue to develop and employ novel combinations of techniques for evaluating structural and functional recovery of disturbed and created habitats. (C) 2004 Elsevier Ltd. All rights reserved.

2002
Levin, LA, Talley TS.  2002.  Natural and manipulated sources of heterogeneity controlling early faunal development of a salt marsh. Ecological Applications. 12:1785-1802.   10.2307/3099938   AbstractWebsite

Ecosystem recovery following wetland restoration offers exceptional opportunities to study system structure, function, and successional processes in salt marshes. This study used observations of natural variation and large-scale manipulative experiments to test the influence of vascular vegetation and soil organic matter on the rate and trajectory of macrofaunal recovery in a southern California created salt marsh, the Crown Point Mitigation Site. During the first three years following marsh establishment, macrofaunal density and species richness recovered rapidly within the Spartina foliosa (cordgrass) zone; densities in the created marsh were 50% of those in the natural marsh after 16 mo and 97% after 28 mo. However, the early successional assemblage had a lower proportion of tubificid and enchytraeid oligochaetes, and a higher proportion of chironomids and other insect larvae than did the mature natural marsh. Most of the colonizers arrived by rafting on sea grass and algae rather than by larval dispersal. Initial planting of S. foliosa had no influence on macrofaunal recovery, perhaps because of variable transplant survival. However, subsequently, both positive and negative correlations were observed between densities of some macrofaunal taxa and shoot densities of S. foliosa or Salicornia spp. (pickleweed). Salinity and measures of soil organics (belowground biomass, combustible organic matter, and chlorophyll a) also were correlated with macrofaunal densities and taxon richness. Of foul added soil amendments (kelp, alfalfa, peat, and Milorganite), Milorganite (a sewage product) and kelp both promoted macrofaunal colonization during year 1, but effects were short lived. The most significant sources of heterogeneity in the recovering marsh were associated with site history and climate variation. Faunal recovery was most rapid in highly localized, organic-rich marsh sediments that were remnants of the historical wetland. Elevated sea level during the 1998 El Nino corresponded with similarity of macrofaunal communities in the created and natural marshes. The large spatial scale and multi-year duration of this study revealed that natural sources of spatial and temporal heterogeneity may exert stronger influence on faunal succession in California wetlands than manipulation of vegetation or soil properties.