Publications

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2014
Neira, C, Levin LA, Mendoza G, Zirino A.  2014.  Alteration of benthic communities associated with copper contamination linked to boat moorings. Marine Ecology-an Evolutionary Perspective. 35:46-66.   10.1111/maec.12054   AbstractWebsite

Although copper (Cu) is an essential element for life, leaching from boat paint can cause excess environmental loading in enclosed marinas. The effects of copper contamination on benthic macrofaunal communities were examined in three San Diego Bay marinas (America's Cup, Harbor Island West and East) in Southern California, USA. The distribution of Cu concentration in sediments exhibited a clear spatial gradient, with hotspots created by the presence of boats, which in two marinas exceeded the effect range medium (ERM). Elevated sediment Cu was associated with differences in benthic assemblages, reduced species richness and enhanced dominance in America's Cup and Harbor Island West, whereas Harbor Island East did not appear to be affected. At sites without boats there were greater abundances of some amphipods such as the species Desdimelita sp., Harpinia sp., Aoroides sp., Corophium sp., Podocerus sp., bivalves such as Lyonsia californica, Musculista senhousia, Macoma sp., and polychaetes such as Diplocirrus sp. In contrast, at sites with boats, densities of Pseudopolydora paucibranchiata, Polydora nuchalis, Euchone limnicola, Exogone lourei, Tubificoides spp. were enhanced. The limited impact on Harbor Island East suggests not only lower Cu input rates and increased water flushing and mixing, but also the presence of adequate defense mechanisms that regulate availability and mitigate toxic impacts. At all three marinas, Cu in tissues of several macrobenthic species exhibited Cu bioaccumulation above levels found in the surrounding environment. The annelids Lumbrineris sp. and Tubificoides spp., and the amphipod Desdimelita sp. contained high levels of Cu, suggesting they function as Cu bioaccumulators. The spionid polychaetes Polydora nuchalis and Pseudopolydora paucibranchiata had much lower Cu concentrations than surrounding sediments, suggesting they function as Cu bioregulators. The macrobenthic invertebrates in San Diego Bay marinas that tolerate Cu pollution (e.g. P.nuchalis, P.paucibranchiata, Euchone limnicola, Typosyllis sp., Tubificoides sp.) may function as indicators of high-Cu conditions, whereas the presence of Cu-sensitive species (e.g. Podocerus sp., Aoroides sp., Harpinia sp., Macoma sp., Lyonsia californica) may indicate healthier conditions (less Cu-stressed). Parallel responses by faunas of Shelter Island Yacht Basin, also in San Diego Bay, suggest potential for development of regional Cu contamination assessment criteria, and call for functional comparisons with other marinas and coastal water bodies.

2009
Neira, C, Delgadillo-Hinojosa F, Zirino A, Mendoza G, Levin LA, Porrachia M, Deheyn DD.  2009.  Spatial distribution of copper in relation to recreational boating in a California shallow-water basin. Chemistry and Ecology. 25:417-433.   10.1080/02757540903334197   AbstractWebsite

The overall effect of the number of boats on the copper (Cu) levels in the water column and sediment, along with their spatial variability within Shelter Island Yacht Basin (SIYB), San Diego Bay, California was examined. We identified a horizontal gradient of increasing dissolved Cu and Cu in sediment from outside to the head of SIYB which was coincident with the increasing number of boats. Spatial models of Cu distribution in water and sediment indicated the presence of 'hotspots' of Cu concentration. From outside to the head of SIYB, dissolved Cu ranged from 1.3 gL-1 to 14.6 gL-1 in surface water, and 2.0 gL-1 to 10.2 gL-1 in bottom water. Cu in sediment exceeded the Effect Range Low of 34mgkg-1 (i.e. where adverse effects to fauna may occur), with a peak concentration of 442mgkg-1 at the head of the basin. Free Cu++ in surface water was several orders of magnitude higher than in sediment porewater. High-resolution data of Cu species together with probability maps presented in this paper will allow managers to easily visualise and localise areas of impaired quality and to prioritise which areas should be targeted to improve Cu-related conditions.

2005
Becker, BJ, Fodrie FJ, McMillan PA, Levin LA.  2005.  Spatial and temporal variation in trace elemental fingerprints of mytilid mussel shells: A precursor to invertebrate larval tracking. Limnology and Oceanography. 50:48-61. AbstractWebsite

Elements incorporated into developing hard parts of planktonic larvae record the environmental conditions experienced during growth. These chemical signatures, termed elemental fingerprints, potentially allow for reconstruction of locations of larvae. Here, we have demonstrated for the first time the feasibility of this approach for bivalve shells. We have determined the spatial scale over which we are able to discriminate chemical signatures in mussels in southern California and characterized the temporal stability of these signals. Early settlers of Mytilus californianus and Mytilus galloprovincialis were collected from eight sites in southern California. Shells were analyzed for nine isotopes using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). We discriminated among mussels collected in two bays and the open coast using Mn, Pb, and Ba shell concentrations. Shell concentrations of Pb and Sr were sufficiently different to discriminate between mussels from the northern and southern regions of the open coast, each representing approximately 20 km of coastline. These signals were relatively stable on monthly and weekly time scales. These results indicate that trace elemental fingerprinting of shell material is a promising technique to track bivalve larvae moving between bays and the open coast or over along-shore scales on the order of 20 km. Identification of spatial variation in elemental fingerprints that is stable over time represents a crucial step in enhancing our ability to understand larval transport and population connectivity in invertebrates.

2001
Ewel, KC, Cressa C, Kneib RT, Lake PS, Levin LA, Palmer MA, Snelgrove P, Wall DH.  2001.  Managing critical transition zones. Ecosystems. 4:452-460.   10.1007/s10021-001-0106-0   AbstractWebsite

Ecosystems that function as critical transition zones (CTZs) among terrestrial, freshwater, and marine habitats are closely connected to the ecosystems adjacent to them and are characterized by a rapid flux of materials and organisms. CTZs play various roles, including mediating water flows, accumulating sediments and organic matter, processing nutrients, and providing opportunities for recreation. They are particularly difficult to manage because they tend to be small, albeit important, components of large watersheds, and managers may not have control over the entire landscape. Moreover, they are often the focus of intensive human activity. Consequently, CTZs are critically important zones, and their preservation and protection are likely to require unique collaboration among scientists, managers, and stakeholders. Scientists can learn a great deal from the study of these ecosystems, taking advantage of small size and the importance of fluxes, but a good understanding of adaptive management strategies is needed to establish a dialogue with managers and stakeholders on technical and management issues. An understanding of risk analysis is also important to help set meaningful goals and establish logical strategies that include all of the interested parties. Successful restoration of a CTZ is the best test of the quality of knowledge about its structure and function. Much has already been learned about coastal CTZs through restoration projects, and the large number of such projects involving riparian CTZs in particular suggests that there is considerable opportunity for fruitful collaborations between scientists and managers.

2000
Dibacco, C, Levin LA.  2000.  Development and application of elemental fingerprinting to track the dispersal of marine invertebrate larvae. Limnology and Oceanography. 45:871-880. AbstractWebsite

The early life history of many marine benthic invertebrate and fish species involves a planktonic larval stage that allows exchange of individuals among separated adult populations. Here, we demonstrate how natural and anthropogenic trace elements can be used to determine larval origins and assess bay-ocean exchange of invertebrate larvae. Trace elements can be effective site markers for estuaries because run-off and pollutant loading often impart distinct elemental signatures to bay habitats relative to nearshore coastal environments. Crab larvae originating from San Diego Bay (SDB) were distinguished from those originating in neighboring embayments and exposed coastal habitats by comparing multiple trace-element concentrations ("fingerprints") in individuals. Discriminant function analysis (DFA) was used to characterize stage I zoeae of the striped shore crab, Pachygrapsus crassipes, of known origin (reference larvae) via trace-elemental composition (i.e., Cu, Zn, Mn, Sr, Ca). Linear discriminant functions were used to identify the origin and characterize the exchange of stage I P. crassipes zoeae between SDB and the nearshore coastal environment during one spring tidal cycle. Elemental fingerprinting revealed that most (87%) of the stage I larvae collected at the bay entrance during the flood tide were larvae of SDB origin that were reentering the bay. Nearly one third of zoeae sampled (32%) at the entrance during ebb tide were coastal larvae leaving the bay and returning to open water. The observed bidirectional exchange contrasts with the unidirectional transport of zoeae out of the bay predicted from stage I vertical migratory behavior. Because P. crassipes zoeal survivorship is lower in SDB than in coastal waters, bay-ocean exchange has significant implications for the dynamics of P. crassipes populations. Trace-elemental fingerprinting of invertebrate larvae promises to facilitate investigations of many previously intractable questions about larval transport and dynamics.

1999
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.