Export 44 results:
Sort by: [ Author  (Desc)] Title Type Year
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
Zirino, A, Elwany H, Neira C, Maicu F, Mendoza G, Levin LA.  2014.  Salinity and its variability in the Lagoon of Venice, 2000–2009. Advances in Oceanography and Limnology. 5:41-59.: Taylor & Francis   10.1080/19475721.2014.900113   Abstract

Yearly averages computed from monthly and bimonthly salinity data collected between 2000 and 2009 from 13 broadly spaced stations in the Venice Lagoon were analysed in view of 30 min data collected semi-continuously during 2009 at nine similarly located stations. Data from all stations and all years indicate that, based on yearly averages, the lagoon may be divided along its major (long) axis into three areas: 1) a northern, freshwater impacted area (S = <28 PSU) of high, tidally-caused, variability, 2) a southern, marine, zone of S >32 PSU of low, tidally-caused, variability, and 3) an intermediate zone. Salinity changes are closely associated with rainfall events, and the incoming freshwater is consistently distributed throughout the lagoon by tidal action. Much variability is simply a result of the forward and backward motion of the tides and is not caused by a salinity change in the water itself. The consistency of the 2000?2009 data and the historical (to 1961) watershed record support the hypothesis that the Venice Lagoon has been and is currently at steady-state with respect to its salinity distribution. As such, it is conducive to the development of (at least) three separate ecosystems.

Zirino, A, Elwany H, Facca C, Maicu F, Neira C, Mendoza G.  2016.  Nitrogen to phosphorus ratio in the Venice (Italy) Lagoon (2001-2010) and its relation to macroalgae. Marine Chemistry. 180:33-41.   10.1016/j.marchem.2016.01.002   AbstractWebsite

Analysis of the annually-averaged 2001-2010 monthly nutrient data from 13 stations in the Venice Lagoon (Italy) shows that the concentrations of dissolved nitrogen (N) species, measured as total dissolved N (TDN), have increased over time while that of phosphorus (P) species, measured as total dissolved P (TDP) have decreased. During the study period, the TDN/TDP ratio in the lagoon rose from about 46:1 to 100:1 (by atoms), a level at which the growth of benthic macroalgae is favored over that of sea grasses. The increase of the TDN/TDP ratio appears to be caused by two factors: (1) a small, but increasing amount of N in river water entering the lagoon, and (2) low P input combined with adsorption and entrapment of orthophosphate on colloidal iron oxides and carbonates at the water-sediment interface. This second mechanism would explain the increase in the TDN/TDP ratio, principally in zones of low salinity, where hydrodynamic residence times are long enough to permit N enrichment and result in macroalgal growth preferentially in the central, landward, side of the lagoon. However, an examination of the algal coverage of the lagoon floor from 2002 to 2010, indicates that while macroalgal abundance may be influenced by the N/P ratio, the spatial and temporal distribution during this period cannot be explained solely by this one feature. Nonetheless, this work points to the importance of considering the contributions that sediments in shallow lagoons make to the over-all system productivity and ecology and may be applicable to other shallow environments. (C) 2016 Elsevier B.V. All rights reserved.

Zirino, A, Neira C, Maicu F, Levin LA.  2013.  Comments on and implications of a steady-state in coastal marine ecosystems. Chemistry & Ecology. 29:86-99.   10.1080/02757540.2012.696613   AbstractWebsite

Coastal ecosystems can be thought of as being established by a number of physico-geochemical drivers, e.g. geochemistry and bathymetry of the basins, climate, tidal and freshwater flows, natural and anthropogenic inputs of nutrients and toxins, all of which exert an influence on the resulting communities of organisms. Depending on the interactions among the major drivers, ecosystems may occur on both large and small scales and be basin-wide or within basins. For individual and separate ecosystems to exist with some permanence in time, e.g. reach a steady-state, they also have to be ‘defended’. Defences are mechanisms that counter changes to maintain the status quo. We argue, and present evidence to support the notion, that the defence mechanisms are inextricably tied to primary production and the biogeochemical cycling of organic matter and provide buffers that mitigate potentially adverse impacts by trace toxins. Colloid pumping, production of complexing ligands and sulfide formation are some of the mechanisms that control trace substances. Current methods for assessing ecosystems do not address the issue of steady-state, nor do they take account of defence activities, e.g. buffering. Therefore, they cannot assess the ‘robustness’ of ecosystems or their ability to resist change, for good or bad. Also, defence mechanisms may, for a time, mask future potentially serious impacts, suggesting that monitoring efforts with limited budgets should consider the measurement of the inputs into ecosystems as well as the immediate or short-term result of the inputs. [ABSTRACT FROM PUBLISHER]Copyright of Chemistry & Ecology is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thurber, AR, Kroger K, Neira C, Wiklund H, Levin LA.  2010.  Stable isotope signatures and methane use by New Zealand cold seep benthos. Marine Geology. 272:260-269.   10.1016/j.margeo.2009.06.001   AbstractWebsite

The carbon isotopic composition of seep faunal tissue represents a time-integrated view of the interaction between biology and the biogeochemical gradients within the environment. Here we provide an initial description of carbon and nitrogen stable isotope signatures of dominant symbiont-bearing megafauna and heterotrophic mega- and macrofauna from 10 methane-seep sites on the continental margin of the North Island of New Zealand (662-1201 m water depth). Isotopic signatures suggest that sulfide oxidation supports symbiont-bearing taxa including solemyid and vesicomyid bivalves, and methanotrophic symbionts are present in the seep mussel Bathymodiolus sp Multiple species of Frenulata (Siboglinidae) are present and have a range of isotopic values that are indicative of both thiotroph- and methanotroph-based nutrition. Isotopic composition of the tubeworm Lamellibrachia sp. varied by 23 3 parts per thousand among individuals although there was no consistent difference among sites Variation in methane use by heterotrophic fauna appears to reflect the availability of hard vs. soft substrate, macrofauna on hard substrates had high delta(13)C signatures, reflecting consumption of photosynthetic-derived organic matter Two unique, biotic assemblages were discovered to be fueled largely by methane: a hard-substrate, multi-phyla sponge-associated community (inhabiting the sponge Pseudosuberites sp) and a soft-sediment assemblage dominated by ampharetid polychaetes Isotope signatures yield estimates of 38-100% and 6-100% methane-derived carbon in sponge associates and ampharetid-bed macrofauna. respectively. These estimates are comparable to those made for deeper methane seeps at the Florida Escarpment (3290 m) and Kodiak. Alaska seeps (4445 m) The overall high use of methane as a carbon source by both symbiont-bearing and heterotrophic fauna suggests that New Zealand methane seeps are an ideal model system to study the interaction among metazoans, bacteria, archaea, and their resulting effect on methane cycles. (C) 2009 Elsevier B V All rights reserved

Sellanes, J, Quiroga E, Neira C, Gutierrez D.  2007.  Changes of macrobenthos composition under different ENSO cycle conditions on the continental shelf off central Chile. Continental Shelf Research. 27:1002-1016.   10.1016/j.csr.2007.01.001   AbstractWebsite

The course of environmental conditions and shelf macrobenthic communities off Central Chile (similar to 36 degrees S) during the strong 1997-98 El Nino (EN) event is compared with a subsequent and basically "normal" period (2002-2003). Changes in macrofaunal community, feeding mode structure, and biomass size spectra are contrasted over time with changes in oceanographic and sediment settings, in order to assess intra- and inter-annual changes in faunal composition during both ENSO periods. During EN, there was a decrease in biomass and abundance of species known to be well adapted to organic-rich, oxygen-deficient environments, such as the interface-feeding polychacte Paraprionospio pinnata. On the other hand the abundance of highly mobile, burrowing polychaetes remained unaffected, or even increased in biomass. The decline of P. pinnata lasted several years after the demise of warm conditions, possibly due to negative interactions with those more mobile burrowing polychaetes. The percent contribution of subsurface-deposit feeders to total biomass increased during EN (49.3 +/- 12.4% during summer) and declined only in the summer-fall period of 2002-03 (11.1 +/- 4.1%). An opposite trend was observed for interface and surface-deposit feeders. From EN to summer-fall 2002-03 (i.e., normal to low oxygen conditions) the size-structure of the macrobenthos switched from a larger to a smaller-sized assemblage. However, biomass was maintained due to successful recruitment and high abundance of both P. pinnata and the squat lobster, Pleuroncodes monodon. Our results suggest that the shelf macrofaunal community structure exhibit fluctuations at various time scales, and that these changes are more pronounced during and after a strong EN event. In such cases, the effects of such an event may be recorded at latitudes as far south as 36 degrees S, with consequences in the biota lasting for many years after the demise of warm conditions. (c) 2007 Elsevier Ltd. All rights reserved.

Sellanes, J, Neira C, Quiroga E.  2003.  Composition, structure and energy flux of the meiobenthos off central Chile. Revista Chilena De Historia Natural. 76:401-415.   10.4067S0716-078X2003000300006.   AbstractWebsite

The general objective of this study was to determine the structure of metazoan meiofauna (at a high taxonomic level) and to estimate its role in the energy flux of the benthic sub-system off Concepcion, Chile (similar to36degrees30' S). Samples were collected in May and November 1997 and May 1998 at five sites located at the: inner Bay of Concepcion (28 m), bay-mouth (35 m), inner-shelf (64 m), mid-shelf (88 in) and outer-shelf (120 m). The study period coincided with the El Nino 1997-1998 (EN) event. The diversity of the meiobenthos was low, but density and biomass were moderate to high compared with average values reported for muddy sub-littoral environments elsewhere. Nematodes were the dominant group, with over 95 % (10(3)-10(4) ind 10 cm(-2)) of the total density, followed by copepods and polychaetes. Highest densities and biomasses were always found at the bay-mouth, followed by the inner-bay and the inner-shelf, while the lowest values occurred at the mid- and outer-shelf. Off Concepcion, the meiofauna plays an important role in the energy flux through the benthic sub-system. Indeed, the meiofauna could be converting to biomass and remineralizing in the inner-bay and bay-mouth up to 36 and 45 %, respectively, of the organic carbon reaching the sediments from the water column.

Sellanes, J, Neira C.  2006.  ENSO as a natural experiment to understand environmental control of meiofaunal community structure. Marine Ecology-an Evolutionary Perspective. 27:31-43.   10.1111/j.1439-0485.2005.00069.x   AbstractWebsite

The sediments of the Bay of Concepcion and the adjacent shelf underlie one of the most productive upwelling areas in the SE Pacific margin. Reports on factors controlling meiofaunal community structure in these kinds of organic-rich and oxygen-deficient habitats are scarce in the literature. In this study, five sites along a transect from the mid-Bay of Concepcion (27 m) to the outer shelf (120 m) were studied on fives dates (May, August, November 1997, and March and May 1998) in order to assess the dynamic relationships between sedimentary organic matter and metazoan meiofauna. The sampling period coincided with the 1997-1998 El Nino event. Sediment parameters investigated were the redox potential discontinuity depth, photosynthetic pigment concentrations (chlorophyll a and phaeopigments), organic carbon, nitrogen, total lipids, carbohydrates, and proteins. In general, lowest values of meiofauna abundance and biomass were found within the naturally eutrophic Bay of Concepcion and towards the shelf break, while maximum values occurred at intermediate depths. During the whole period, the meiofaunal abundance was negatively correlated with the concentration of most of the biochemical components of organic matter, as well as with the sediment phaeopigment content. However, positive correlations were found with chlorophyll a derived indices and with bottom-water oxygen content. Most of the sediment parameters displayed a seasonal cycle, but towards the beginning of 1998, an effect of the 1997-1998 El Nino was evident. Typical austral -summer (i.e. oxygen-deficient) conditions did not develop, and sedimentary parameters reflected a decreased input of phytodetritus. Along the transect, the magnitude of this effect on meiofauna varied among sites. An overall positive response, in terms of meiofaunal abundance was observed, probably due to the amelioration of low oxygen conditions in the sediment.

Sellanes, J, Neira C, Gallardo VA, Gutierrez D, Soto A.  1999.  Meiofauna metazoaria en una zona de surgencia costera de Chile central: relaciones con factores abioticos durante El Nino 1997-1998. Libro de resumenes ampliados : VIII COLACMAR (VIII Congreso Latinoamericano sobre Ciencias del Mar, 17-21 de octubre 1999, Trujillo, Perú). ( Tresierra Aguilar AE, Culquichicon Malpica ZG, Eds.)., Trujillo, Peru: UNT [Mexico] Abstract
Sellanes, J, Quiroga E, Neira C.  2008.  Megafauna community structure and trophic relationships at the recently discovered Concepcion Methane Seep Area, Chile, ~36°S. Ices Journal of Marine Science. 65:1102-1111.   10.1093/icesjms/fsn099   AbstractWebsite

The fauna, community composition, and trophic support of the newly discovered Concepcion Methane Seep Area (CMSA) are compared with those at a nearby non-seep control. The assemblage of chemosymbiotic bivalves is defined by eight species, including the families Lucinidae, Thyasiridae, Solemyidae, and Vesicomyidae. Seep polychaetes are represented by Lamellibrachia sp. and two commensal species of the vesicomyid Calyptogena gallardoi. Although taxonomic analysis is still under way, most of the chemosymbiotic species seem to be endemics. The CMSA is a hotspot for non-seep benthic megafauna too; 101 taxa were present, but most of them are colonists or vagrants (i.e. not endemics of methane seeps). Isotope analysis supported the belief that non-symbiont-bearing species utilize photosynthetically fixed carbon, because they were isotopically distinct from the chemosymbiotic bivalve species present. It is our opinion that, at this site, which underlies one of the most productive coastal upwelling regions of the world, spatial heterogeneity and the availability of hard substratum, generated by the presence of authigenic carbonate crusts, are more important factors in attracting non-seep fauna than the availability of locally produced chemosynthetic food.

Sellanes, J, Neira C, Quiroga E, Teixido N.  2010.  Diversity patterns along and across the Chilean margin: a continental slope encompassing oxygen gradients and methane seep benthic habitats. Marine Ecology-an Evolutionary Perspective. 31:111-124.   10.1111/j.1439-0485.2009.00332.x   AbstractWebsite

In the present study we review datasets available for the Chilean margin to assess the relationship between environmental (or habitat) heterogeneity and benthic diversity. Several factors, such as the presence of different water masses, including the oxygen-deficient Equatorial Sub-surface Waters (ESSW) at the continental shelf and upper slope, and the Antarctic Intermediate Waters (AIW) at mid slope depths appear to control the bathymetric distribution of benthic communities. The presence of methane seeps and an extended oxygen minimum zone (OMZ) add complexity to the benthic distribution patterns observed. All these factors generate environmental heterogeneity, which is predicted to affect the diversity patterns both along and across the Chilean continental margin. The response to these factors differs among different faunal size groups: meio-, macro-, and megafauna. Physiological adaptations to oxygen deficiency and constraints related to body size of each group seem to explain the larger-scale patterns observed, while sediment/habitat heterogeneity (e.g. at water mass boundaries, hardgrounds, biogeochemical patchiness, sediment organic content, grain size) may influence the local fauna diversity patterns.

Rathburn, AE, Levin LA, Tryon M, Gieskes JM, Martin JM, Perez ME, Fodrie FJ, Neira C, Fryer GJ, Mendoza G, McMillan PA, Kluesner J, Adamic J, Ziebis W.  2009.  Geological and biological heterogeneity of the Aleutian margin (1965-4822 m). Progress in Oceanography. 80:22-50.   10.1016/j.pocean.2008.12.002   AbstractWebsite

Geological, biological and biogeochemical characterization of the previously unexplored margin off Unimak Island, Alaska between 1965 and 4822 m water depth was conducted to examine: (1) the geological processes that shaped the margin, (2) the linkages between depth, geomorphology and environmental disturbance in structuring benthic communities of varying size classes and (3) the existence, composition and nutritional sources of methane seep biota on this margin. The study area was mapped and sampled using multibeam sonar, a remotely operated vehicle (ROV) and a towed camera system. Our results provide the first characterization of the Aleutian margin mid and lower slope benthic communities (micro-biota, foraminifera, macrofauna and megafauna), recognizing diverse habitats in a variety of settings. Our investigations also revealed that the geologic feature known as the "Ugamak Slide" is not a slide at all, and could not have resulted from a large 1946 earthquake. However, sediment disturbance appears to be a pervasive feature of this margin. We speculate that the deep-sea occurrence of high densities of Elphidium, typically a shallow-water foraminiferan, results from the influence of sediment redeposition from shallower habitats. Strong representation of cumacean, amphipod and tanaid crustaceans among the Unimak macrofauna may also reflect sediment instability. Although some faunal abundances decline with depth, habitat heterogeneity and disturbance generated by canyons and methane seepage appear to influence abundances of biota in ways that supercede any clear depth gradient in organic matter input. Measures of sediment organic matter and pigment content as well as C and N isotopic signatures were highly heterogeneous, although the availability of organic matter and the abundance of microorganisms in the upper sediment (1-5 cm) were positively correlated. We report the first methane seep on the Aleutian slope in the Unimak region (3263-3285 m), comprised of clam bed, pogonophoran field and carbonate habitats. Seep foraminiferal assemblages were dominated by agglutinated taxa, except for habitats above the seafloor on pogonophoran tubes. Numerous infaunal taxa in clam bed and pogonophoran field sediments and deep-sea "reef' cnidarians (e.g., corals and hydroids) residing on rocks near seepage sites exhibited light organic delta(13)C signatures indicative of chemosynthetic nutritional sources. The extensive geological, biogeochemical and biological heterogeneity as well as disturbance features observed on the Aleutian slope provide an attractive explanation for the exceptionally high biodiversity characteristic of the world's continental margins. (C) 2008 Elsevier Ltd. All rights reserved.

Neira, C, Rackemann M.  1996.  Black spots produced by buried macroalgae in intertidal sandy sediments of the Wadden Sea: Effects on the meiobenthos. Journal of Sea Research. 36:153-170.   10.1016/s1385-1101(96)90786-8   AbstractWebsite

The effects of buried decaying macroalgae on meiobenthos were examined in intertidal sandy sediments of the Wadden Sea of Lower Saxony. In situ experiments confirmed that one of the principal causes of the formation of reduced surface sediments or 'black spots' on the tidal flats is the increasing occurrence and subsequent decomposition of filamentous green algae (Enteromorpha spp.) buried in the sediment. Five to fifteen days after algal material had been buried, the sediment surface turned black. The impact of these black spots on meiobenthos was dramatic: the changed chemical conditions in the sediment resulted in long and drastic reductions in meiofaunal abundance and number of taxa. A multi-dimensional scaling (MDS) analysis of data on meiobenthic abundances revealed that samples from black-spot areas were clearly separated from those of control and reference areas. Re-oxidized black spots showed recolonization by meiofaunal animals, with numbers of individuals and taxa similar to those of oxidized surface sediments. The use of abundances of members of higher meiobenthic taxa to monitor changes in the sediment's chemistry, especially those caused by biomass overload, is discussed.

Neira, C, Levin LA, Grosholz ED, Mendoza G.  2007.  Influence of invasive Spartina growth stages on associated macrofaunal communities. Biological Invasions. 9:975-993.   10.1007/s10530-007-9097-x   AbstractWebsite

In coastal wetlands, invasive plants often act as ecosystem engineers altering flow, light and sediments which, in turn, can affect benthic animal communities. However, the degree of influence of the engineer will vary significantly as it grows, matures and senesces, and surprisingly little is known about how the influence of an ecosystem engineer varies with ontogeny. We address this issue on the tidal flats of San Francisco Bay where hybrid Spartina (foliosa x alterniflora) invaded 30 years ago. The invasion has altered the physico-chemical properties of the sediment habitat, which we predicted should cause changes in macrofaunal community structure and function. Through mensurative and manipulative approaches we investigated the influence of different growth stages of hybrid Spartina on macrobenthos and the underlying mechanisms. Cross-elevation sampling transects were established covering 5 zones (or stages) of the invasion, running from the tidal flat (pre-invasion) to an unvegetated dieback zone. Additionally, we experimentally removed aboveground plant structure in the mature (inner) marsh to mimic the 'unvegetated areas'. Our results revealed four distinct faunal assemblages, which reflected Spartina-induced changes in the corresponding habitat properties along an elevation gradient: a pre-invaded tidal flat, a leading edge of immature invasion, a center of mature invasion, and a senescing dieback area. These stages of hybrid Spartina invasion were accompanied by a substantial reduction in macrofaunal species richness and an increase in dominance, as well as a strong shift in feeding modes, from surface microalgal feeders to subsurface detritus/Spartina feeders (mainly tubificid oligochaetes and capitellid polychaetes). Knowledge of the varying influence of plant invaders on the sediment ecosystem during different phases of invasion is critical for management of coastal wetlands.

Neira, C, Silva M, Iorizi M, Minale L.  1992.  Marine organic chemistry .5. Asterosaponins from the starfish Heliaster helianthus. Boletin De La Sociedad Chilena De Quimica. 37:139-142. AbstractWebsite

A chemical study of the starfisf Heliaster helianthus is reported. The polar extract yielded four glucosides, a new xylosides 1, thornasterosides A 2, the xyloside 3 with a known aglycone and glacialoside A 4.

Neira, C, Grosholz ED, Levin LA, Blake R.  2006.  Mechanisms generating modification of benthos following tidal flat invasion by a Spartina hybrid. Ecological Applications. 16:1391-1404.   10.1890/1051-0761(2006)016[1391:mgmobf];2   AbstractWebsite

Many coastal habitats are being substantially altered by introduced plants. In San Francisco Bay,, California, USA, a hybrid form of the eastern cordgrass Spartina alterniflora is rapidly invading open mudflats in southern and central sections of the Bay, altering habitat, reducing macrofaunal densities, and shifting species composition. The invasion has resulted in significant losses of surface-feeding amphipods, bivalves, and cirratulid polychaetes, while subsurface feeding groups such as tubificid oligochaetes and capitellid polychaetes have been unaffected. In the present paper, we document the causes and mechanisms underlying the changes observed. Through a series of in situ manipulative experiments we examined the influence of hybrid Spartina canopy on a range of physical, chemical, and biological properties. The hybrid Spartina canopy exerted a strong influence on. the hydrodynamic regime, triggering a series of physical, chemical, and biological changes in the benthic system. Relative to tidal flats, water velocity was reduced in hybrid patches, promoting deposition of fine-grained, organic-rich particles. The resulting changes in the sediment environment included increased porewater sulfide concentrations and anoxia, which led to poor survivorship. of surface feeders such as, bivalves, amphipods, and polychaetes. These are key taxa that support higher trophic levels including migratory shorebirds that feed on tidal flats. Altered flow in the Spartina canopy further contributed to changes in barnacle recruitment and resuspension of adult benthic invertebrates. Increased crab-induced predation pressure associated with Spartina invasion also contributed to changes in benthic invertebrate communities. Our results suggest that multiple physical, chemical, biotic, and trophic impacts of the Spartina invasion have resulted in substantial changes in benthic communities that are likely to have important effects on the entire ecosystem.

Neira, C, Gad G, Arroyo NL, Decraemer W.  2001.  Glochinema bathyperuvensis sp. n. (Nematoda, Epsilonematidae): A new species from Peruvian bathyal sediments, SE Pacific Ocean. Contributions to Zoology. 70:147-159. AbstractWebsite

Glochinema bathyperuvensis sp. n., the first record of Epsilonematidae from bathyal muddy sediments of the oxygen minimum zone (OMZ) off Callao, Peru (eastern Pacific Ocean) is described. The new species belongs to the subfamily Glochinematinae and is characterized by the possession of more than 8 pairs of subdorsal thorns asymmetrically arranged and a single dorsal one in the pharyngeal region, as well as by the presence of ten to thirteen blade-like cuticular protrusions forming a latero-dorsal palisade around the posterior head region and anterior cervical region, In addition, G. bathyperuvensis is characterized by its large size, more than 240 cuticular annules, provided with an extremely dense,hairy'' body ornamentation and, four rows of ambulatory setae: two inner subventral ones with 8 to 9 setae in males, and 5 to 6 setac in females, and two outer subventral rows composed each of 9-12 ambulatory setae followed by a large number of modified somatic setae. The dense hairy body spines, the large number of modified somatic setae, its dominant occurrence exclusive in oxygen-depleted, organic-rich soupy surface sediments indicate an adaptation to the stressed OMZ habitat conditions.

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.

Neira, C, Levin LA, Grosholz ED.  2005.  Benthic macrofaunal communities of three sites in San Francisco Bay invaded by hybrid Spartina, with comparison to uninvaded habitats. Marine Ecology-Progress Series. 292:111-126.   10.3354/meps292111   AbstractWebsite

A hybrid cordgrass, formed from a cross between Spartina alterniflora (Atlantic cordgrass) and S. foliosa (Pacific cordgrass), has recently spread within the intertidal zone of south San Francisco Bay. Sediment properties and macroinfaunal community structure were compared in patches invaded by Spartina hybrid and adjacent uninvaded patches at 3 sites in San Francisco Bay (2 tidal flats and 1 Salicornia marsh). We hypothesized that (1) sediments vegetated by Spartina hybrid would have reduced sediment grain size, higher organic matter content, lower redox potential, lower salinity and reduced microalgal biomass relative to adjacent unvegetated tidal flat sediments, and (2) that differences in the sediment environment would correspond to changes in the infaunal invertebrate community structure and feeding modes. We observed 75 % lower total macro-faunal density and lower species richness in Spartina-vegetated sediments at Elsie Roemer (30 yr old invasion) than in an adjacent unvegetated tidal flat. This was due to lower densities of surface-feeding amphipods, bivalves, cirratulid and spionid polychaetes. The proportional representation of subsurface-deposit feeders was greater in Spartina patches than in unvegetated sediments. At a more recently invaded site (Roberts Landing; 15 yr invasion), Spartina patches differed from tidal flat sediments in composition, but not in abundance. Native (Salicornia) and Spartina patches exhibited similar sediment properties at San Mateo, where the Spartina hybrid invaded 8 to 10 yr earlier. No differences were detected in densities or proportions of surface- or subsurface-deposit feeders, but the proportion of carnivores/omnivores and grazers increased in the hybrid-invaded patches. These studies suggest that the invasive Spartina hybrid in south San Francisco Bay can have differing effects on sediment ecosystems, possibly depending on the location, age, or type of habitats involved.

Neira, C, Höpner T, Rackemann M.  1998.  Annual course of sediment parameters and meiofauna on a sandy tidal flat in the Wadden Sea after the severe winter of 1995/96. Deutsche Hydrografische Zeitschrift. 50:301-311.: Springer-Verlag   10.1007/BF02764227   AbstractWebsite

Local abiotic and biotic data are presented from the Gröninger Plate (a sandy tidal flat south of Spiekeroog Island) covering a period of one year (February 1996 — February 1997), which includes the coldest part of the ice winter of 1995/96 as well as the winter of 1996/97. The thickness of the visible oxidized layer revealed a clear seasonality. Regarding sandy sediments, values were generally low and ranged between 2.9 cm in winter and 0.9 cm in summer. Biotic and abiotic data are restricted to composition and abundance of meiofauna taxa, total organic carbon, Chl a and phaeopigments as well as temperature and salinity. A significant reduction of meiofaunal abundance, particularly of nematodes, in the top 2 cm was recorded in samples taken in sediments covered by ice, as compared to sediments without an ice cover. However, vertical distribution of meiofauna under ice cover showed that nematodes had migrated to deeper sediment layers. The meiofauna appeared to have overcome the stress of low temperatures and ice formation better than the macrofauna.

Neira, C, Mendoza G, Levin LA, Zirino A, Delgadillo-Hinojosa F, Porrachia M, Deheyn DD.  2011.  Macrobenthic community response to copper in Shelter Island Yacht Basin, San Diego Bay, California. Marine Pollution Bulletin. 62:701-717.   10.1016/j.marpolbul.2011.01.027   AbstractWebsite

We examined Cu contamination effects on macrobenthic communities and Cu concentration in invertebrates within Shelter Island Yacht Basin, San Diego Bay, California. Results indicate that at some sites, Cu in sediment has exceeded a threshold for "self defense" mechanisms and highlight the potential negative impacts on benthic faunal communities where Cu accumulates and persists in sediments. At sites with elevated Cu levels in sediment, macrobenthic communities were not only less diverse but also their total biomass and body size (individual biomass) were reduced compared to sites with lower Cu. Cu concentration in tissue varied between species and within the same species, reflecting differing abilities to "regulate" their body load. The spatial complexity of Cu effects in a small marina such as SIYB emphasizes that sediment-quality criteria based solely on laboratory experiments should be used with caution, as they do not necessarily reflect the condition at the community and ecosystem levels. (C) 2011 Elsevier Ltd. All rights reserved.

Neira, C, Cossaboon J, Mendoza G, Hoh E, Levin LA.  2017.  Occurrence and distribution of polycyclic aromatic hydrocarbons in surface sediments of San Diego Bay marinas. Marine Pollution Bulletin. 114:466-479.   10.1016/j.marpolbul.2016.10.009   Abstract

Polycyclic aromatic hydrocarbons (PAHs) have garnered much attention due to their bioaccumulation, carcinogenic properties, and persistence in the environment. Investigation of the spatial distribution, composition, and sources of PAHs in sediments of three recreational marinas in San Diego Bay, California revealed significant differences among marinas, with concentrations in one site exceeding 16,000 ng g− 1. ‘Hotspots’ of PAH concentration suggest an association with stormwater outfalls draining into the basins. High-molecular weight PAHs (4–6 rings) were dominant (> 86%); the average percentage of potentially carcinogenic PAHs was high in all sites (61.4–70%) but ecotoxicological risks varied among marinas. Highly toxic benzo(a)pyrene (BaP) was the main contributor (> 90%) to the total toxic equivalent quantity (TEQ) in marinas. PAHs in San Diego Bay marina sediments appear to be derived largely from pyrogenic sources, potentially from combustion products that reach the basins by aerial deposition and stormwater drainage from nearby streets and parking lots.

Neira, C, Hopner T.  1993.  Fecal pellet production and sediment reworking potential of the polychaete Heteromastus filiformis show a tide dependent periodicity. Ophelia. 37:175-185. AbstractWebsite

The sediment reworking potential of Heteromastus filiformis (a capitellid polychaete) was determined in a laboratory mesocosm by collecting and counting fecal pellets deposited on the sediment surface at 6-hour intervals over several simulated tidal cycles. Pellet production rates showed a marked 6-hour periodicity. Production was highest during the flooding and decreased during the ebbing tide. In the absence of a simulated tidal cycle, there was no periodicity in pellet production. With an annual mean population density of 1200 individuals/m2 in the Jadebusen Bay, Wadden Sea, the quantity of sediment reworked by H. filiformis is about 175 ml/m2/day or 64 l/m2/year, which is approximately a deep-sediment layer of 6 cm, transported to the surface annually . Pellet production by Heteromastus contributes substantially to the recycling of detritus and nutrients in the Wadden Sea, especially in areas with high population densities.

Neira, C, Sellanes J, Levin LA, Arntz WE.  2001.  Meiofaunal distributions on the Peru margin: relationship to oxygen and organic matter availability. Deep-Sea Research Part I-Oceanographic Research Papers. 48:2453-2472.   10.1016/s0967-0637(01)00018-8   AbstractWebsite

A quantitative study of metazoan meiofauna was carried out on bathyal sediments (305, 562, 830 and 1210 m) along a transect within and beneath the oxygen minimum zone (OMZ) in the southeastern Pacific off Callao, Peru (12 degreesS). Meiobenthos densities ranged from 1517 (upper slope, middle of OMZ) to 440-548 ind. 10cm(-2) (lower slope stations, beneath the OMZ). Nematodes were the numerically dominant meiofaunal taxon at every station, followed by copepods and nauplii. Increasing bottom-water oxygen concentration and decreasing organic matter availability downslope were correlated with observed changes in meiofaunal abundance. The 300-m site, located in the middle of the OMZ, differed significantly in meiofaunal abundance, dominance, and in vertical distribution pattern from the deeper sites. At 305 m, nematodes amounted to over 99% of total meiofauna; about 70% of nematodes were found in the 2-5 cm. interval. At the deeper sites, about 50% were restricted to the top I cm. The importance of copepods and nauplii increased consistently with depth, reaching similar to 12% of the total meiofauna at the deepest site. The observation of high nematode abundances at oxygen concentrations <0.02mll(-1) supports the hypothesis that densities are enhanced by an indirect positive effect of low oxygen involving (a) reduction of predators and competitors and (b) preservation of organic matter leading to high food availability and quality. Food input and quality, represented here by chloroplastic pigment equivalents (CPE) and sedimentary labile organic compounds (protein, carbohydrates and lipids), were strongly, positively correlated with nematode abundance. By way of contrast, oxygen exhibited a strong negative correlation, overriding food availability, with abundance of other meiofauna such as copepods and nauplii. These taxa were absent at the 300-m site. The high correlation of labile organic matter (C-LOM, sum of carbon contents in lipids, proteins and carbohydrates) with CPE (Pearson's r = 0.99, p <0.01) suggests that most of the sedimentary organic material sampled was of phytodetrital origin. The fraction of sediment organic carbon potentially available to benthic. heterotrophs, measured as C-LOM/Total organic carbon, was on average 17% at all stations. Thus, a residual, refractory fraction, constitutes the major portion of organic matter at the studied bathyal sites. (C) 2001 Elsevier Science Ltd. All rights reserved.

Neira, C, Mendoza G, Porrachia M, Stransky C, Levin LA.  2015.  Macrofaunal recolonization of copper-contaminated sediments in San Diego Bay. Marine Pollution Bulletin. 101:794-804.   10.1016/j.marpolbul.2015.09.023   AbstractWebsite

Effects of Cu-loading on macrofaunal recolonization were examined in Shelter Island Yacht Basin (San Diego Bay, California). Sediments with high and low Cu levels were defaunated and Cu-spiked, translocated, and then placed back into the environment These demonstrated that the alteration observed in benthic communities associated with Cu contamination occurs during initial recolonization. After a 3-month exposure to sediments with varying Cu levels, two primary colonizing communities were identified: (1) a "mouth assemblage" resembling adjacent background fauna associated with low-Cu levels that was more diverse and predominantly dominated by surface- and subsurface-deposit feeders, burrowers, and tube builders, and (2) a "head assemblage" resembling adjacent background fauna associated with high-Cu concentrations, with few dominant species and an increasing importance of carnivores and mobile epifauna. Cu loading can cause reduced biodiversity and lower structural complexity that may last several months if high concentrations persist, with a direct effect on community functioning. (C) 2015 Elsevier Ltd. All rights reserved.