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Mehring, AS, Levin LA.  2015.  Potential roles of soil fauna in improving the efficiency of rain gardens used as natural stormwater treatment systems. Journal of Applied Ecology. 52:1445-1454.   10.1111/1365-2664.12525   AbstractWebsite

Natural treatment systems such as rain gardens aim to overcome the negative effects of urbanization on water quality, availability, and freshwater and marine ecosystem integrity by mimicking the natural water cycle in urban planning and design. While soils in these systems are inhabited by a diverse array of invertebrates, the soil macrofauna is ignored in the vast majority of studies on new or existing rain gardens. Here, we review the functional roles of invertebrates commonly found within soils of rain gardens. Soil fauna have the potential to substantially alter plant growth, water infiltration rates, and the retention and removal of pathogens, nutrients, heavy metals and other contaminants. Their lack of inclusion in controlled laboratory or greenhouse studies may contribute to differences in observed function in field and laboratory settings. Promising future research directions include the following: (i) the use of controlled experiments to study invertebrate effects on rain garden function; (ii) determining the factors affecting variability in organismal abundance among and within sites; and (iii) the design of rain gardens to facilitate development of fauna that promote desired functions.Synthesis and applications. Soil fauna may substantially alter the function of rain gardens as natural stormwater treatment systems in urban areas. Therefore, incorporat-ing animal effects into design and testing may better enable managers and researchers tounderstand and optimize rain garden functioning, and forecast the longevity of rain gardens. Soil fauna may substantially alter the function of rain gardens as natural stormwater treatment systems in urban areas. Therefore, incorporat-ing animal effects into design and testing may better enable managers and researchers tounderstand and optimize rain garden functioning, and forecast the longevity of rain gardens.

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.

Talley, TS, Levin LA.  1999.  Macrofaunal succession and community structure in Salicornia marshes of southern California. Estuarine Coastal and Shelf Science. 49:713-731.   10.1006/ecss.1999.0553   AbstractWebsite

Lack of basic understanding of ecosystem structure and function forms a major impediment to successful conservation of coastal ecosystems. This paper provides a description of the fauna and examines faunal succession in Salicornia-vegetated sediments of southern California. Environmental attributes (vegetation and sediment properties) and macrofaunal (animals greater than or equal to 0.3 mm) community structure were examined in sediments of five natural, southern California Salicornia spp. marshes (Tijuana Estuary, San Diego Bay, Mission Bay, Upper Newport Bay and Anaheim Bay) and in created Salicornia marshes 16 months to 10 years in age, located within four of the bays. Oligochaetes and insects were the dominant taxa in both natural (71 to 98% of total fauna) and created (91 to 97%) marshes. In San Diego, Newport and Anaheim Bays, macrofaunal densities were generally higher in the created marshes (88 000 to 290 000 ind m(-2)) than in their natural counterparts (26 000 to 50 000 ind m(-2)). In the youngest system, Mission Bay, the reverse was true (natural: 113 000 vs created: 28 000 ind m-2). Similar species numbers were recorded from the created and adjacent natural marshes. Insects, especially chironomids, dolichopodids, and heleids, as well as the naidid oligochaete, Paranais litoralis, characterize early successional stages. Enchytraeid and tubificid oligochaetes reflect later succession evident in natural and older created marshes. Sediment organic matter (both combustible and below-ground plant biomass) was the environmental variable most commonly associated with densities of various macrofaunal taxa. These relationships were generally negative in the natural marshes and positive in the created marshes. Within-bay comparisons of macrofauna from natural Salicornia- vs Spartina-vegetated habitat in San Diego and Mission Bays revealed lower macrofaunal density (San Diego Bay only), proportionally fewer oligochaetes and more insects, and no differences in species richness in the Salicornia habitat. The oldest created Salicornia marsh (San Diego Bay) exhibited an assemblage intermediate in composition between those of the natural Salicornia- and Spartina-vegetated marshes. These results suggest: (a) faunal recovery following Salicornia marsh creation can require 10 or more years, (b) high macrofaunal variability among bays requires marsh creation reference site selection from within the same bay, and (c) Spartina-based research should not be used for Salicornia marsh management decisions. (C) 1999 Academic Press.