scholarly journals Comparative drilling predation on time-averaged phosphatized and nonphosphatized assemblages of the minute clypeasteroid echinoidEchinocyamus stellatusfrom Miocene offshore sediments (Globigerina Limestone Formation, Malta)

2017 ◽  
Vol 91 (4) ◽  
pp. 633-642 ◽  
Author(s):  
Tobias B. Grun ◽  
Andreas Kroh ◽  
James H. Nebelsick
Keyword(s):  
Time Averaging ◽  
Sedimentation Rates ◽  
Northern Coast ◽  
Maltese Islands ◽  
Aboral Side ◽  
Drilling Predation ◽  
Drill Holes ◽  
Offshore Sediments

AbstractFossilized tests of 1,053Echinocyamus stellatus(Capeder, 1906) from the Miocene Globigerina Limestone Formation exposed on the northern coast of Gozo (Maltese Islands) were analyzed for predation traces. Specimens mixed by time-averaging processes can be clearly separated into two distinct samples according to their preservation as phosphatized or nonphosphatized individuals. Overall, 11.1% of the tests reveal holes that are referred to the ichnospeciesOichnus simplex(Bromley, 1981). Because of the hole morphology and diameter, the holes are interpreted as predatory drill holes, most likely produced by cassid gastropods. Redeposited phosphatized echinoids derived from an earlier period of reduced sedimentation rates show drilling frequencies of 20.5%. Younger, autochthonous, nonphosphatized echinoids show drilling frequencies of 8.1%. In both samples, predators predominantly targeted the aboral side of the echinoid test, particularly on the petalodium.

Time averaging and stratigraphic unmixing: reconstructing ecological decline in molluscan production (Holocene, Brijuni, NE Adriatic)

2020 ◽  
Author(s):  
Adam Tomašových ◽  
Martin Zuschin ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Coralline Algae ◽  
Time Averaging ◽  
Sedimentation Rates ◽  
Amino Acid Racemization ◽  
Ecological History ◽  
Shell Bed ◽  
Warm Temperate

<p>The northeastern Adriatic seafloor is formed by warm-temperate bioclastic carbonates with coralline algae, bryozoans and mollusks. These sediments represent a mixture of past and present-day production owing to low sedimentation rates and bioturbation. Although low sedimentation rates do not allow resolution of ecological history at centennial or even millennial scales on the basis of raw stratigraphic data, age unmixing based on radiocarbon-calibrated amino acid racemization shows that one of the major molluscan sediment producers – the infaunal suspension-feeder Timoclea ovata  – markedly peaked in production ~5,000 years during the maximum flooding and earliest highstand phase and significantly diminished in abundance during the late highstand phase at Brijuni, with a large proportion of dead shells now present in surface sediments representing shells that are several centuries old. This species still occurs in living assemblages but our analyses indicate that its former production was by several orders of magnitude higher. In contrast, stratigraphic trends in absolute and proportional abundance of this species in ~1.5 m-thick sediment cores show a gradual or a very mild upcore decline, indicating that raw stratigraphic data do not efficiently detect millennial-scale ecological dynamic. The temporal decline in production of Timoclea ovata is associated with an increase in water depth and an increase in sediment-accumulation rate, and led to a transition from molluscan oyster-scallop shell bed to late highstand bryomol sediments.</p>

Taphonomic Bias in Analyses of Drilling Predation: Effects of Gastropod Drill Holes on Bivalve Shell Strength

Palaios ◽  
1994 ◽  
Vol 9 (4) ◽  
pp. 413 ◽  
Author(s):  
Kaustuv Roy ◽  
Daniel J. Miller ◽  
Michael Labarbera
Keyword(s):  
Drilling Predation ◽  
Predation Effects ◽  
Bivalve Shell ◽  
Drill Holes

scholarly journals Modeling of Sediment Transport in Bothnian Bay in the Vicinity of the Nuclear Power Plant ‘Hanhikivi-1’ Construction Site

2019 ◽  
Vol 7 (7) ◽  
pp. 229 ◽  
Author(s):  
Stanislav D. Martyanov ◽  
Anton Yu. Dvornikov ◽  
Vladimir A. Ryabchenko ◽  
Dmitry V. Sein
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Sediment Accumulation ◽  
Middle Part ◽  
Sedimentation Rates ◽  
Northern Coast ◽  
Coupled Modeling ◽  
North East ◽  
Bothnian Bay

The intensity of sediment resuspension and sedimentation in the eastern part of the Bothnian Bay near the Hanhikivi cape, where the nuclear power plant ‘Hanhikivi-1’ will be constructed, has been assessed for the first time by means of numerical modeling under the realistic external forcing that occurred in 2014. A brief description of a coupled modeling system used in the study is given. The results of local resuspension intensity and sediment accumulation rates for one-year model run are presented. It has been determined that the main areas of sediment accumulation are located along the northern coast off the Hanhikivi peninsula and in the shallow region situated to the north-east off the cape. Sedimentation rates in the navigation channel have also been estimated. Model results obtained for 2014 suggest that sedimentation in the seaward part of the channel is absent, while sediment accumulation intensity is about 10 cm/year in the middle part of the channel and 70 cm/year in the coastal part. A temporal variability of the sedimentation rates during the year has been emphasized.

ENCOUNTER FREQUENCY DOES NOT PREDICT PREDATION FREQUENCY IN TROPICAL DEAD-SHELL ASSEMBLAGES

Palaios ◽  
2015 ◽  
Vol 30 (12) ◽  
pp. 818-826 ◽  
Author(s):  
JULIETA C. MARTINELLI ◽  
MATTHEW A. KOSNIK ◽  
JOSHUA S. MADIN
Keyword(s):  
Prey Species ◽  
Size Range ◽  
Prey Size ◽  
Species Level ◽  
Soft Sediment ◽  
Ecological Communities ◽  
Drilling Predation ◽  
Drill Holes ◽  
Molluscan Assemblage ◽  
Shed Light

Abstract Predation is frequently suggested to be a key biotic process that can shape ecological communities and drive coevolution. The premise behind these hypotheses is that predators select prey to ensure maximum gain per unit effort; for example, by selecting species that are more abundant or accessible. In this study, we tested for predator selectivity in a tropical molluscan assemblage by quantifying the influence of relative abundance (encounter frequency) on predation frequencies. We collected macromollusks (> 4 mm) from 15 sites in three soft-sediment reef lagoons at One Tree Reef (southern Great Barrier Reef, Australia). Dead mollusks were counted and identified to species level (61 species, n  =  8131), and species predation frequencies were calculated as the proportion of shells with drill holes. We found that in this infauna-dominated community, levels of drilling predation were low (7.14% on average), and there was no evidence that predators selected prey based on encounter frequency. This result was consistent across prey species and lagoons. Thus, drilling predators did not specialize on more accessible prey species and were not a major cause of mortality in this modern macromollusk assemblage. Since drilling gastropods are size selective, lack of selectivity in our samples only applies to the prey size range considered. Detailed studies of prey morphological traits, as well as accounting for predator non-consumptive effects could shed light on the preferences and relevance of drilling gastropods in this soft-sediment carbonate reef assemblage.

Naticid drilling predation from tidal flats in northern Patagonia, SW Atlantic

2020 ◽  
Vol 100 (6) ◽  
pp. 909-919
Author(s):  
Sandra Gordillo ◽  
Mariano E. Malvé ◽  
Gisela A. Morán ◽  
Gabriella M. Boretto
Keyword(s):  
Spatial Scales ◽  
Predator Prey ◽  
Northern Patagonia ◽  
Argentine Patagonia ◽  
Drilling Predation ◽  
Local Patterns ◽  
Latitudinal Patterns ◽  
Sw Atlantic ◽  
Regional Factors ◽  
Drill Holes

AbstractNaticids and muricids are the main drilling gastropod families that leave a characteristic hole in their shelled prey. Drilling predation can be evaluated along spatial scales, and different latitudinal patterns (equatorward, poleward, mid-latitude peaks or no trend at all) have already been described. For Argentine Patagonia, most studies have analysed muricid predation, but scant information is available on naticid predation. This study provides evidence of predation by the moon snail Notocochlis isabelleana on a thin and fragile burrowing bivalve, Darina solenoides, along the intertidal sandflats at Pozo Salado, San Matías Gulf, in northern Patagonia. To estimate the incidence of predation, articulated specimens of Darina solenoides (N = 432) were randomly collected in the intertidal zone. Drill holes (N = 94) were recorded in shell lengths ranging between 10 and 35 mm. Taking into account previous studies in the region, the intensity of mortality by drilling (22%) constitutes a higher value than expected for this latitude. These results may help explain local patterns in a particular site in northern Patagonia which has been previously identified as an outlier, but further studies aimed at evaluating macrogeographic patterns are necessary for a better understanding of the regional factors that might be governing these predator–prey interactions.

scholarly journals Holocene and Late Glacial sedimentation near steep slopes in southern Lake Baikal

2015 ◽  
Author(s):  
Michael Sturm ◽  
Elena G. Vologina ◽  
Svetlana S. Vorob’eva
Keyword(s):  
Shallow Water ◽  
Lake Baikal ◽  
Water Depth ◽  
Deep Water ◽  
Fine Particles ◽  
Sedimentation Rates ◽  
Northern Coast ◽  
Rare Type ◽  
The Holocene ◽  
Low Concentrations

<p>We here present new data on sedimentation at and near the steep north-slopes of southern Lake Baikal. Short sediment cores were taken at 550 m and at 1366 m water depth, within 3600 m offshore Cape Ivanovskii at the station of the <em>Baikal Deep Underwater NEUTRINO</em> <em>Telescope</em>. The sediments within 3600 m off the northern coast of Southern Lake Baikal are dominated by pelagic deposition. Our data reveal surprisingly little influence from terrigenous material from adjacent coastal areas, tributaries and their catchment. At the shallow-water site (at 550 m water depth, 700 m off shore) just 27 cm thick homogenous sediments have accumulated during the Holocene on top of Pleistocene deposits resulting in Holocene sedimentation rates of 0.003 cm a<sup>-1</sup>. The very low rates are caused by long-term persistent winnowing of fine particles caused by week contour currents along the slope. The uppermost sediments are oxidized down to 22 cm. Very low concentrations of C<sub>org</sub>, Si<sub>bio</sub> and N<sub>tot</sub> in Pleistocene sediments increase dramatically within the Holocene. The heavy mineral fraction of the shallow-water sediments contains up to 33.6 % olivine and up to 2.4 % spinel. These rare minerals originate from white marbles of the nearby coastal outcrop <em>Belaya Vyemka</em> of the Early Precambrian <em>Sharyzalgaiskaya</em> <em>Series</em>. At the deep-water site (at 1366 m water depth, 3600 m off shore) Holocene sedimentation rates are 10-times higher (0.036 cm a<sup>-1</sup>). Sediment oxidation occurs just within the uppermost 2 cm. Of the two rare type minerals of the <em>Sharyzalgaiskaya</em> <em>Series</em> spinel does not occur at all and olivine is represented by very diminished concentrations. This indicates insignificant influx of terrestrial material from the nearby shore to the deep-water site . Distal turbidites of far-off sources are intercalated to pelagic sediments at the deep-water site. Breakdown events of deltas at the SE- and S-coast of the basin are suggested to be responsible for the formation of the turbidites. They contain terrestrial (deltaic) material, low amounts of biological material (diatoms, spiculae, chrysophyte cysts), low concentrations of Si<sub>bio</sub>, C<sub>org </sub>and N<sub>tot</sub> and occur at approximate recurrence rates of 300 years. </p>

scholarly journals Paleoecology of naticid–molluscan prey interaction during the Late Jurassic (Oxfordian) in Kutch, India: evolutionary implications

2021 ◽  
pp. 1-20
Author(s):  
Subhendu Bardhan ◽  
Sandip Saha ◽  
Shiladri S. Das ◽  
Ranita Saha
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Prey Selection ◽  
Western India ◽  
Predator Prey ◽  
Important Prey ◽  
Drilling Predation ◽  
Prey Interaction ◽  
Drill Holes

Abstract We document and quantify one of the oldest predator–prey interactions between naticid gastropods and molluscan prey, on the basis of drill holes in shells, from the Late Jurassic (Oxfordian) beds of Kutch, western India. Previously, many workers recorded naticid-like drill holes on prey taxa from the Triassic and the Jurassic, but in the absence of associated naticid body fossils, they remained equivocal. The present gastropod community is dominated by turritellines (98% of the sample) that form the turritelline-dominated assemblage, and the naticid drilling predation is restricted almost entirely to turritellines among gastropods. Confamilial naticid predation takes place occasionally. Within the bivalve community, corbulids and nuculids are most abundant and are drilled more often than other taxa. These observations indicate that prey selection was opportunistic and based solely on availability. Drilling intensities at both assemblage and lower taxon levels are low. Behavioral stereotypy of naticid predation in some cases is moderately high. Turritellines are often the preferred prey of naticid gastropods since the late Early Cretaceous. These two groups form a recurrent association reflecting prey–predator interaction. Here we suggest that both turritellines and naticids evolved during the Jurassic, and the prey–predator interaction between them was established shortly thereafter. Among bivalves, corbulids also became important prey of naticids in the same spatiotemporal framework. Corbulids are older than naticids and first appeared during the Middle Jurassic. After their first encounter with naticids, corbulids evolved conchiolin layers within the valves to resist predation.

Shell ornamentation as a likely exaptation: evidence from predatory drilling on Cenozoic bivalves

Paleobiology ◽  
2015 ◽  
Vol 41 (1) ◽  
pp. 187-201 ◽  
Author(s):  
Adiël A. Klompmaker ◽  
Patricia H. Kelley
Keyword(s):  
Evolutionary History ◽  
Drill Hole ◽  
Time Interval ◽  
Bivalve Species ◽  
Important Process ◽  
Drilling Predation ◽  
Hole Position ◽  
History Of ◽  
Drill Holes ◽  
Time And Energy

AbstractPredation is an important process in modern oceans and in the evolutionary history of marine ecosystems. Consequently, it has been hypothesized that shelled prey modified their ornamentation in response to predation. However, bivalve ornamentation has also been argued to be important in maintaining a stable life position in the sediment and in burrowing. To test whether concentric ribs were effective against drilling by carnivorous gastropods, we examined drill hole position and completeness for four Cenozoic bivalve species that differ in rib strength (Astarte radiata,A. goldfussi,Lirophora glyptocyma, andL. latilirata). The percentage of drill holes located between the ribs increases with increasing rib strength, whereas the percentage of drill holes on top of ribs decreases. This result suggests that gastropods select the drill hole site more effectively as rib strength increases, thereby saving time and energy, and that natural selection favors gastropods that select drill hole sites between ribs. Because of this greater stereotypy, the percentage of drill holes that are incomplete is generally lower in strongly ribbed species. The proportion of drill holes located on top of ribs is greater for incomplete than complete holes, implying that ribs can be effective against predators, but only when selected as the drilling location. We show that ribs are most effective against drilling predation for bivalves with moderately sized ribs, between which gastropods have difficulty siting drill holes. Concentric ribs are unlikely to have evolved as an adaptation against drilling predation because concentric ribs evolved in the Paleozoic and were already common in the Mesozoic, whereas drilling frequency increased later, in the Late Cretaceous–Paleogene. Moreover, rib strength of North AmericanAstartedid not change through this time interval. Thus, the ribs considered here are a likely exaptation to drilling given their effectiveness at deterring drilling predation on bivalves with moderate ribs.

scholarly journals Occurrence and distribution of different bed types of seagrass Posidonia oceanica around the Maltese Islands

2009 ◽  
Vol 10 (2) ◽  
pp. 45 ◽  
Author(s):  
J.A. BORG ◽  
A.A. ROWDEN ◽  
M.J. ATTRILL ◽  
P.J. SCHEMBRI ◽  
M.B. JONES
Keyword(s):  
Large Scale ◽  
Posidonia Oceanica ◽  
Eastern Coast ◽  
Small Scale ◽  
Northern Coast ◽  
Maltese Islands ◽  
The North ◽  
Bare Sand ◽  
Sandy Substratum ◽  
Continuous Beds

The small-scale distribution of Posidonia oceanica bed types were mapped at four locations off the northern coast of the Maltese Islands, using aerial photography supplemented by surveys using SCUBA diving. Results showed a similar pattern of occurrence of the seagrass at all locations surveyed. In shallow waters (2 m – 4 m), P. oceanicaoccurred as patches of variable size on a rocky and/or sandy substratum. In deeper waters (5 m – 10 m), the patches of seagrass were often replaced by reticulate beds consisting of P. oceanicainterspersed with areas of bare sand. Deeper still (11 m – 13 m), a transition from reticulate to continuous beds occurred. Continuous beds extended to depths of around 25 - 30 m and eventually became reticulate or patchy in deeper waters (>25 m). Values of total seagrass percentage cover increased, while the ratio of fragmented:continuous bed cover decreased for the four study locations on moving southwards (Ramla Bay to St Thomas Bay), indicating that P. oceanica habitat was more abundant and less fragmented in the south-eastern parts of the Maltese Islands. However, values calculated using an exposure index did not did indicate a relationship between exposure and the observed decease in fragmentation of seagrass beds on moving northwest to southwest along the north-eastern coast. Data from the four sites surveyed, together with data from other surveys, were used to show the large-scale distribution of P. oceanica beds around the Maltese Islands. The implications of the study findings for the conservation and management of P. oceanica habitat around the Maltese Islands are discussed.

scholarly journals Mesophotic depth biogenic accumulations (“biogenic mounds”) offshore the Maltese Islands, central Mediterranean Sea

2021 ◽  
Author(s):  
Or Bialik ◽  
Andrea Varzi ◽  
Ruth Duran Gallego ◽  
Timothy Le Bas ◽  
Adam Gauci ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Cold Water ◽  
Anthropogenic Impacts ◽  
Benthic Communities ◽  
Eastern Coast ◽  
Sedimentation Rates ◽  
Glacial Cycle ◽  
Central Mediterranean ◽  
Maltese Islands ◽  
The Last Glacial

The mesophotic domain is a poorly explored part of the oceans, notably in the Mediterranean Sea. Benthic communities in these depths are not well documented and as such are under higher risk from anthropogenic impacts. Hard substrate habitats in this depth window are not common and are a key ecotope. The Malta Plateau in the central Mediterranean, which is characterised by low sedimentation rates, offers a potentially unexplored domain for these features. Bathymetric and backscatter data offshore of the eastern coast of the island of Malta were used to characterise the benthic habitats. >1700 small structures were identified in mesophotic depth and verified by dives to be biogenic mounds. These mounds extend from several meters to tens of meters in diameter and occur in two main depth windows 40 to 83 mbpsl and 83 to 120 mbpsl, each formed probably in a different stage along the last glacial cycle. The mounds are composed of interlocking bioconstruction by encrusting organisms and are colonised by sponges and various cold water corals (most of which are protected). This unique and important habitat is currently under grave threat by human activity, most immediately by trawling activity.

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