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Levin, LA, Talley D, Thayer G.  1996.  Succession of macrobenthos in a created salt marsh. Marine Ecology-Progress Series. 141:67-82.   10.3354/meps141067   AbstractWebsite

Early succession of macrofauna was examined over several years in a created Spartina alterniflora marsh located on the Newport River Estuary, North Carolina, USA. Epifauna and infaunal community structure and composition were compared at 2 elevations in plots planted with S. alterniflora, plots left bare of vegetation and vegetated plots in a nearby natural S, alterniflora marsh. No significant successional differences were observed between vegetated and unvegetated sediments in the created marsh. The earliest stages of colonization involved recruitment by opportunistic estuarine polychaetes: Streblospio benedicti, Capitella spp, and Polydora cornuta. Capitella spp. dominated the macrofauna a month after marsh creation, but thereafter S. benedicti was the most abundant species. During the first few years, the artificial marsh retained early successional characteristics, with S, benedicti, Capitella spp. and turbellarians accounting for 75 to 95% of the total macrofauna. Fiddler crabs were common epifaunal colonists. After 4 yr, species richness increased and dominance by the early colonists diminished. Taxa lacking planktonic larvae and swimming adults were particularly slow to recover in the created marsh, but accounted for over 25% of the infauna by Year 4. Oligochaetes, which comprised over 50% of the fauna in the natural marsh, remained absent or rare in the artificial system throughout the study. Infaunal recovery appears to be more rapid in lower than upper marsh elevations. Although macrofaunal densities and species richness of sediments in the lower created marsh came to resemble those of the natural marsh within 6 mo, species composition and faunal feeding modes did not. These observations suggest there may be significant functional differences between young artificial marshes and older natural marshes. Consideration of the timing of marsh creation, marsh configuration, continuity with natural marshes, seeding of taxa with poor dispersal, and attention to species habitat requirements are recommended to accelerate infaunal colonization of created Spartina marshes.

Gooday, AJ, Levin LA, Thomas CL, Hecker B.  1992.  The distribution and ecology of Bathysiphon filiformis sars and B. major de folin (Protista, Foraminiferida) on the continental slope off North Carolina. Journal of Foraminiferal Research. 22:129-146. AbstractWebsite

Two large species of the agglutinated foraminifera genus Bathysiphon are common in samples and photographs from bathyal depths on the North Carolina continental slope: B. filiformis off Cape Hatteras (588-930 m bathymetric depth) and B. major off Cape Lookout (850-1950 m depth). The sampling area, and particularly the 850 m station where B. filiformis is abundant (mean densities of 59-154 per m2), is believed to receive large inputs of organic material from various sources. This is consistent with the previously observed occurrence of large Bathysiphon species in regions of high food supply. Ten camera sled transects across the eastern U.S. continental slope between 32-degrees-N and 41-degrees-N emphasize the abundance of B. filiformis in the Cape Hatteras area compared with its rarity or absence elsewhere along the continental slope. Box cores, bottom photographs, and direct submersible observations indicate that B. filiformis tubes project above the sediment in an arcuate curve with only the lower 1 cm or so buried. Bathysiphon major adopts a similar orientation but has a greater proportion (50-80%) of the tube buried. The voluminous, dense, granular protoplasm of both species contains biogenic particles (including diatoms, in B. filiformis only), dinoflagellate cysts, fungal remains, pollen grains, tintinnid loricae, polychaete jaws and setae, benthic foraminiferal tests, and fish tooth fragments), suggesting that they feed mainly on material derived from the sediment surface. Submersible observations indicate that B. filiformis is patchily distributed at 100 m scales. Smaller scale dispersion patterns (analyzed from photographs) are generally random but with a tendency to be aggregated at lower densities and uniform at higher densities. A variety of metazoans and foraminifers live epifaunally on the outer surfaces of B. filiformis tubes. The most frequently occurring metazoans were larvae and juveniles of an unidentified gastropod and a tubiculous terebellid polychaete Nicolea sp. The most common epifaunal foraminifers were Tritaxis conica and Trochammina sp. Tubes of B. major, however, are virtually devoid of epifauna. Our results support the view that large, agglutinated rhizopod tests may influence the structure of deep-water benthic communities. However, in the case of Bathysiphon on the North Carolina continental slope, the effect appears limited to taxa directly associated with the foraminiferal tubes.

Levin, LA, McCann LD, Thomas CL.  1991.  The ecology of polychaetes on deep seamounts in the eastern Pacific Ocean. Ophelia. :467-476. AbstractWebsite

Polychaetes were collected by the submersible ALVIN on 18 deep (788-3,353 m) seamounts in the eastern Pacific Ocean at 10-degrees, 13-degrees, 20-degrees and 30-degrees N off western Mexico. Polychaetes comprised 57.7% of all macrofauna collected. Average density over all locations was 942 polychaetes/m2. Thirty-eight families were represented among the 1,422 infaunal polychaetes collected. Five families, the Paraonidae, Cirratulidae, Syllidae, Ampharetidae, and Sabellidae, attained average densities > 1 individual/196 cm2 core. We evaluated effects of latitude, local setting, depth, and substrate on polychaete abundance, taxonomic composition, and lifestyles. Unusually high polychaete densities (7,194/m2) and low diversities were observed in a shallow caldera (788 m) at 13-degrees N. Excluding this site, the latitude exhibiting the highest polychaete densities (xBAR = 939/m2) was 10-degrees N. Of the seven settings examined, pit craters (within seamount calderas) supported the highest densities (xBAR = 1031/m2), and hydrothermal oxide fields and seamount bases exhibited the lowest polychaete densities (xBAR = 576-612/m2). Rippled foraminiferal sands on volcano summits supported large numbers of filter feeders, particularly sabellids. Regressions of total polychaete abundance on depth and on percent sand were not significant. Large, epifaunal, sediment-agglutinating protozoans (Phylum Sarcodina: Class Xenophyophorea) provided habitat for 34 polychaete species. Polychaete abundance and family composition were generally similar to those reported for other nearshore, deep-sea environments at comparable depths. With the exception of the shallowest site, species richness was typically high.

Levin, LA, Thomas CL.  1989.  The influence of hydrodynamic regime on infaunal assemblages inhabiting carbonate sediments on central Pacific seamounts. Deep-Sea Research Part a-Oceanographic Research Papers. 36:1897-&.   10.1016/0198-0149(89)90117-9   AbstractWebsite

We investigated the following hypotheses for deep seamounts in the central Pacific Ocean: (1) infaunal and microbial abundances are elevated in regions of current intensification, (2) infaunal lifestyles reflect variation in hydrodynamic conditions and (3) bioturbation is more intense in high-energy regimes. Our studies were carried out at three sites: the northwest perimeter of the Horizon Guyot sediment cap (1840 m), which is characterized by strong bottom currents and rippled foraminiferan sands, and the central summits of Horizon Guyot (1480 m) and Magellan Rise (3150 m), whose sediments are unrippled and finer grained. Contrary to our first hypothesis, the high-energy, Horizon perimeter sediments exhibited lower biological activity than the summit sites, as reflected in lower organic nitrogen (0.011% vs. 0.015–0.017%), higher C/N ratios (19 vs 11), lower bacterial counts (1.21 vs 2.03−2.15 × 108ml−1) and lower macrofaunal abundances (255 vs 388–829 m−2). Sediment organic carbon values (0.14–0.19%) and meiofaunal abundances (2866–5150 m−2) did not differ significantly among the three sites.Infaunal life habits varied among sites but sediment mixing did not. Macrofauna were found deeper in rippled perimeter sediments than in the cap sediments. Sessility and surface-feeding modes dominated among polychaetes at the higher-energy Horizon perimeter, while motility and subsurface feeding were common in the quieter, finer-grained regimes. Significant sediment mixing takes place on 100-year time scales a all three sites, probably a result of large, infaunal bioturbators at the cap sites and physical sediment instability at the perimeter site. Excess 210Pb exhibited moderately high inventories (38–59 dpm cm−2) and deep penetration (15 cm). Estimated mixing coefficients (Db) ranged from 0.6 to 3.0 cm2y−1 at the three sites. Our findings indicate that hydrodynamic differences can lead to greater variation in sediment and faunal characteristics on a single seamount than are found in similar regimes on different seamounts.Comparison of the Horizon Guyot and Magellan Rise data to comparable data from eastern Pacific seamounts, reveals lower organic carbon content, microbial abundance, macrofaunal densities, and subsurface deposit feeder representation, in central than eastern Pacific seamount sediments.

Kayen, RE, Schwab WC, Lee HJ, Torresan ME, Hein JR, Quinterno PJ, Levin LA.  1989.  Morphology of sea-floor landslides on Horizon Guyot: application of steady-state geotechnical analysis. Deep-Sea Research Part a-Oceanographic Research Papers. 36:1817-1839.   10.1016/0198-0149(89)90114-3   AbstractWebsite

Mass movement and erosion have been identified on the pelagic sediment cap of Horizon Guyot, a seamount in the Mid-Pacific Mountains. Trends in the size, shape and preservation of bedforms and sediment textural trends on the pelagic cap indicate that bottom-current-generated sediment transport direction is upslope. Slumping of the sediment cap occurred on and that the net bedload transport direction is upslope. Slumping of the sediment cap occurred on the northwest side of the guyot on a 1.6° to 2.0° slope in the zone of enhanced bottom-current activity. Submersible investigations of these slump blocks show them to be discrete and to have a relief of 6–15 m, with nodular chert beds cropping out along the headwall of individual rotated blocks. An evaluation of the stability of the sediment cap suggests that the combination of the current-induced beveling of the sea floor and infrequent earthquake loading accompanied by cyclic strength reduction is responsible for the initiation of slumps. The sediment in the area of slumping moved short distances in relatively coherent masses, whereas sediment that has moved beyond the summit cap perimeter has fully mobilized into sediment gravity flows and traveled large distances. A steady-state geotechnical analysis of Horizon Guyot sediment indicates the predisposition of deeply buried sediment towards disintegrative flow failure on appropriately steep slopes. Thus, slope failure in this deeper zone would include large amounts of internal deformation. However, gravitational stress in the near-surface sediment of the summit cap (sub-bottom depth< 14 m) is insufficient to maintain downslope movement after initial failure occurs. The predicted morphology of coherent slump blocks displaced and rafted upon a weakened zone at depth corresponds well with seismic-reflection data and submersible observations.

Levin, LA, Thomas CL.  1988.  The ecology of xenophyophores (Protista) on eastern Pacific seamounts. Deep-Sea Research Part a-Oceanographic Research Papers. 35:2003-2027.   10.1016/0198-0149(88)90122-7   AbstractWebsite

Large, agglutinating protozoans of the class Xenophyophorea are the dominant epifaunal organisms on soft and hard substrates of many bathyal seamounts in the eastern Pacific Ocean off Mexico. Observations made with the submersible Alvin and remotely towed camera sleds on 17 seamounts at 31°, 20°, 13° and 10°N revealed more than ten distinct xenophyophore test morphologies. Most of these appear to represent previously undescribed species. Reticulate forms are numerically dominant at 20°, 13° and 10°N. Xenophyophore abundances increase with decreasing latitude, being rare at 30°N, present at densities of 0.1–1.0 m−2 at 20° and 13°N and often exceeding 1.0 m−2 at 10°N, occasionally reaching 10–18 m−2. Highest concentrations are observed on caldera floors near the base of steep caldera walls, at depths between 1700 and 2500 m. Most individuals select sand-size pelagic foraminiferan tests (63–500 μm) and exclude pebble, silt and clay-size particles for test construction.Xenophyophore on seamounts modify the structure of metazoan communities and may play a role in maintenance of infaunal diversity. Twenty-seven xenophyophore tests were found to provide habitat for 16 major macrofaunal taxa (152 individuals) and three meiofaunal taxa (333 individuals). The presence of xenophyophores also enhances the abundance of isopods, tanaids, ophiuroids, nematodes and harpacticoid copepods dwelling in sediments surrounding the tests. Mobile megafauna are attracted to sediment beneath and adjacent to xenophyophores. We suggest that xenophyophores, which are abundant on many topographic features in deep water (e.g. guyots, trenches, canyons and continental slopes), are a functionally important component of deep-sea benthic communities and require further autecological and synecological investigation.

Levin, LA, Demaster DJ, McCann LD, Thomas CL.  1986.  Effects of giant protozoans (Class Xenophyophorea) on deep-seamount benthos. Marine Ecology-Progress Series. 29:99-104.   10.3354/meps029099   AbstractWebsite

Biogenic sediment structures have been proposed to enhance diversity in deep-sea sediments. To evaluate this hypothesis we examined the influence of xenophyophores, giant sediment-agglutinating protozoans, on the structure of metazoan communities inhabiting sediments of deep (1000 to 3300 m) seamounts in the eastern Pacific Ocean. Xenophyophores provided habitat for 16 major metazoan taxa. Sediments immediately surrounding xenophyophores exhibited elevated faunal densities and species richness relative to control sediments collected 1 m from the tests. Amphipods were exclusively associated with the protozoan tests or sediments beneath them. Crustaceans, molluscs, and echinoderms exhibited enhanced infaunal densities in the presence of xenophyophores but polychaetes did not. Both horizontal and vertical distributions of infauna appear to be influenced by these protozoans. 234Th measurements suggest that xenophyophores and their associated fauna increase the particle flux of fine-grained material to the seabed and enhance subsurface mixing on a 100 d time scale. We propose that xenophyophores alter hydrodynamic conditions and provide deep-sea metazoans with substrate, food, and refuge. The resulting habitat heterogeneity may contribute to maintenance of high benthic diversity.

Tegner, MJ, Levin LA.  1983.  Spiny lobsters and sea urchins: Analysis of a predator-prey interaction. Journal of Experimental Marine Biology and Ecology. 73:125-150.   10.1016/0022-0981(83)90079-5   AbstractWebsite

Spiny lobsters, Panulirus interruptus (Randall), are important predators of two species of sea urchins, Strongylocentrotus franciscanus (A. Agassiz) and S. purpuratus (Stimpson), which are major herbivores in southern California kelp forest communities. Aquarium experiments indicate that spiny lobsters strongly prefer S. purpuratus over S. franciscanus of comparable test diameter, probably accounting for the higher number of S. purpuratus mortalities observed in the field. Juvenile S. franciscanus (< 60 mm test diameter, TD) are preferred over larger conspecifics, but the smallest S. franciscanus (< 30 mm TD) are protected by association with the adult urchin spine canopy. Mid-sized S. franciscanus too large to fit under the spine canopy are subject to intense predation. All sizes of P. interruptus tested showed a notable reluctance to attack large S. franciscanus (> 90 mm TD) when offered a range of sizes, although the larger lobsters are capable of handling the largest urchins. Relative movement, spine length, test thickness, and gonad weights of sea urchins were examined to evaluate the factors affecting the lobsters' choice of prey, and behavioral responses to lobsters were assessed to determine urchin availability to these predators. The handling problems associated with the long spines of larger S. franciscanus appear to be the major considerations in prey choice despite the much greater potential energy gain from these urchins. Thus predation by spiny lobsters appears to be sufficient to explain the bimodal size-frequency distribution typical of S. franciscanus populations in areas where these predators are common. Heavy fishing pressure on spiny lobsters during this century probably resulted in the release of sea urchin populations and contributed to episodes of destructive urchin grazing observed in the 1950's and subsequent years.

Tegner, MJ, Levin LA.  1982.  Do sea urchins and abalones compete in California kelp forest communities? Echinoderms, proceedings of the International Conference, Tampa Bay. ( Lawrence JM, Ed.).:265-271., RotterdamSalem, NH: A.A. Balkema ;Distributed in USA & Canada by MBS Abstract