DUROPHAGOUS FISH PREDATION TRACES VERSUS TUMBLING-INDUCED SHELL DAMAGE—A PALEOBIOLOGICAL PERSPECTIVE

Palaios ◽  
2020 ◽  
Vol 35 (1) ◽  
pp. 37-47
Author(s):  
MARIUSZ A. SALAMON ◽  
TOMASZ BRACHANIEC ◽  
PRZEMYSŁAW GORZELAK
Keyword(s):  
Fish Predation ◽  
Physical Factors ◽  
Individual Crystal ◽  
Shell Damage ◽  
Fish Predators ◽  
History Of ◽  
Good Proxy ◽  
Predatory Fishes ◽  
Crystal Fibers ◽  
Shell Fragments

ABSTRACT Durophagous (shell-crushing) fish predation is considered to have been a major force of evolutionary change in the history of marine communities. However, because fish predators are very rarely preserved in the act of predation, fossil evidence of such interactions is commonly indirect. For instance, it has been argued that shell fragments with sharp margins constitute a good proxy for durophagy. However, drawing a distinction between predation- and abiotic-induced shell damage can be challenging. Notably, experimental data on shell fragmentation by marine durophagous fishes are almost lacking. In this study, we explore whether shell breakage caused by durophagous marine fishes versus physical factors can be distinguished. Aquarium experiments involving commercially available predatory fishes (Diodon) and thin-shelled invertebrate preys (gastropods Nassarius and brachiopods Frenulina) show that the predation by some fish produces shell fragments displaying extremely low roundness and varying degree of sphericity. Importantly, these fragments typically display sharp and jagged margins, and reveal distortion of individual crystal fibers. Tumbling experiments showed that the disintegration of brachiopod shells proceeds much more rapidly than that of gastropods, which may suggest that abiotic-induced fragmentation of brachiopods may be eventually confused with predation. However, the tumbling-induced fragmentation and damage in both groups are typically characterized by the presence of spherical or discoidal and rounded shell fragments displaying smooth edges (without any microstructural distortion), and numerous abrasive scratches and wear scars on the surface. These data underscore that the shell fragments produced by a durophagous fish, if not subsequently abraded by physical factors, can be recognized in the fossil record.

Trends in shell fragmentation as evidence of mid-Paleozoic changes in marine predation

Paleobiology ◽  
10.1666/13018 ◽  
2014 ◽  
Vol 40 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Mariusz A. Salamon ◽  
Przemysław Gorzelak ◽  
Robert Niedźwiedzki ◽  
Dawid Trzęsiok ◽  
Tomasz K. Baumiller
Keyword(s):  
Fish Predation ◽  
Taxonomic Diversity ◽  
Physical Factors ◽  
Predator Prey ◽  
Marine Communities ◽  
Shell Damage ◽  
Mode Of Life ◽  
Extinction Events ◽  
Shell Fragments ◽  
Independent Confirmation

Recent observations indicate that shell fragmentation can be a useful tool in assessing crushing predation in marine communities. However, criteria for recognizing shell breakage caused by durophagous predators versus physical factors are still not well established. Here, we provide data from tumbling and aquarium experiments to argue that physical and biotic processes lead to different patterns of shell damage, specifically that angular shell fragments are good indicators of durophagous predation. Using such angular shell fragments as a predation proxy, we analyze data from 57 European Paleozoic localities spanning the Ordovician through the Mississippian. Our results reveal a significant increase in angular shell fragments (either occurring as isolated valves or present in regurgitalites) in the Mississippian. The timing of this increase is coincident with the increased diversity of crushing predators as well as marked anti-predatory changes in the architecture and mode of life of invertebrate prey observed after the end-Devonian Hangenberg extinction (359 Ma). More specifically, the observed trend in shell fragmentation constitutes strong and independent confirmation of a recently suggested end-Devonian changeover in the primary method of fish predation from shearing to crushing. These results also highlight the important effect of extinction events, not only on taxonomic diversity, but also on the nature of predator-prey interactions.

PERKEMBANGANKAWASAN PECINAN SEMARANG

2017 ◽  
Vol 10 (6) ◽  
pp. 361
Author(s):  
Monica Latu Melati ◽  
Ariadne Kristia Nataya ◽  
Alfonsus Arianto Wibowo
Keyword(s):  
Urban Form ◽  
Secondary Data ◽  
Primary Data ◽  
Physical Factors ◽  
Review Analysis ◽  
Urban Heritage ◽  
Observation Area ◽  
Cultural Artefact ◽  
History Of ◽  
Special District

Abstract:Semarang Chinatown  is a special  district in Semarang City  known with its chineese culture, where chineese citizen of Semarang have been living  for centuries. The sustained chineese culture in this area makes Semarang Chinatwon as an urban heritage and cultural artefact in Semarang City. The aims for this paper are to investigate the factors shaping Chinatown Semarang, the development of Chinatown Semarang from time  to time, the urban form elements in Semarang Chinatown, and the correlation between morphological components of Semarang Chinatown. This writing use some review methods, first theoritical overview to get secondary data about physical or non-physical factors forming city, second observation area such as collecting photos and interviewing to get primary data. Data review analysis use qualitative data analysis which is configure with the problems and aims that have been appointed.Keywords:elements of urban form, morphological components, history of Semarang ChinatownAbstrak: Kawasan Pecinan Semarang adalah sebuah kawasan di kota Semarang yang sangat kental dengan budaya Tionghoa. Di sinilah warga keturunan Tionghoa sejak berabad-abad silam menetap di Semarang. Adanya budaya Tionghoa yang masih sangat terjaga menjadikan Kawasan Pecinan Semarang ini sebagai kawasan urban heritage dan artefact budaya di kota Semarang. Tujuan penulisan adalah untuk menemukan faktor pembentuk Kawasan Pecinan Semarang, mengetahui perkembangan Kawasan Pecinan Semarang dari masa ke masa, mengetahui pola bentuk dan elemen kawasan pada Kawasan Pecinan Semarang, serta mengetahui kaitan antara faktor pembentuk kawasan terhadap perkembangan Kawasan Pecinan Semarang. Penulisan ini menggunakan metode kajian berupa tinjauan teori untuk memperoleh data sekunder mengenai faktor-faktor pembentuk kota baik secara fisik maupun non fisik, serta observasi lapangan berupa pengumpulan foto yang dilengkapi dengan wawancara untuk memperoleh data primer. Analisis data kajian dilakukan dengan menggunakan analisis data kualitatif yang disesuaikan dengan permasalahan dan tujuan yang telah ditetapkan.Kata kunci:Elemen Kawasan, Faktor Pembentuk Kawasan, PerkembanganSejarah Kawasan Pecinan Semarang

scholarly journals Productivity Growth and Machinery Investment: A Long-Run Look, 1870–1980

1992 ◽  
Vol 52 (2) ◽  
pp. 307-324 ◽  
Author(s):  
J. Bradford De Long
Keyword(s):  
Economic Growth ◽  
Productivity Growth ◽  
Rapid Growth ◽  
History Of Technology ◽  
High Rate ◽  
Past Century ◽  
The Past ◽  
Long Run ◽  
History Of ◽  
Good Proxy

Over the past century in six major economies, economic growth has been strongly associated with machinery investment, as is the case for a larger group of nations since 1950. Both macroeconomic patterns and narratives of the history of technology suggest that this association is causal—that a high rate of machinery investment appears to be a necessary prerequisite for rapid long-run growth—and points away from possibilities that rapid growth is the cause of high machinery investment or that a high rate of machinery investment is a good proxy for other factors that are important causes of growth.

Cephalopods as prey. IV. Fishes

1996 ◽  
Vol 351 (1343) ◽  
pp. 1067-1081 ◽  
Keyword(s):  
Prey Capture ◽  
The Arctic ◽  
Potential Prey ◽  
Nurse Shark ◽  
Pelagic Fishes ◽  
Important Prey ◽  
Continental Shelves ◽  
Time Period ◽  
Fish Predators ◽  
Predatory Fishes

Predatory fishes that consume cephalopods have broad spectrum diets that include other groups, such as fishes and crustaceans. Extremely few fish predators feed on cephalopods to the virtual exclusion of other prey, although the tawny nurse shark Nebrius ferrugineus and the sicklefin weasel shark Hemigaleus microstoma may be exceptions, and some deep-living spiny dogfish may feed largely on cephalopods when they are available. Cephalopods are rarely taken in estuaries but they become more important prey on continental shelves and squids may be more dominant prey during their spawning aggregations. Cephalopods generally become more important components of the diets of larger predatory fishes, such as sharks, that inhabit the continental slope and rise. They may be important to pelagic fishes, such as swordfish and tunas in some parts of the oceans. Cephalopods are rarely taken by benthic Antarctic fishes but they are important prey of some pelagic fishes in the Arctic. Abundance and size of potential prey is critical, and the behaviour of both predator and potential prey is decisive, in prey choice. Factors such as prey switching with growth, between areas and at different times, have major influences on the diets of predators. There are extremely few studies that obtain rigorous enough data to allow quantitative analysis of the significance of cephalopods (or other prey) in the diets of predatory fishes and even the most comprehensive studies are not predictive because findings relate only to the time period of each study. Nevertheless, cephalopods are important components of most marine food webs and, furthermore, may play an indirect role in facilitating prey capture to secondary predators, and in providing rejecta to benthic scavengers.

scholarly journals Density- and trait-mediated effects of fish predators on amphipod grazers: potential indirect benefits for the giant kelp Macrocystis pyrifera

2020 ◽  
Author(s):  
A Perez-Matus ◽  
Jeffrey Shima
Keyword(s):  
Grazing Pressure ◽  
Giant Kelp ◽  
Primary Producers ◽  
Secondary Importance ◽  
Predator Species ◽  
Indirect Benefits ◽  
Positive Effects ◽  
Behavioural Effects ◽  
Fish Predators ◽  
Predatory Fishes

Indirect effects of predators on primary producers may arise when predators suppress herbivore abundance and/or alter the behaviour patterns of herbivores in ways that reduce grazing pressure. Most studies highlight the role of predators in reducing herbivore abundance (i.e. density- mediated interactions), while behavioural effects (i.e. trait-mediated interactions) induced by predators are less commonly considered and are often assumed to be of secondary importance. We used a mesocosm experiment to evaluate the consumptive and behavioural effects of 2 species of predatory fishes on amphipod grazers that feed and nest on the giant kelp Macrocystispyrifera. Only one, Noto- labrus celidotus, of the 2 predator species reduced grazer abundance. Although the second predator species, N. fucicola, did not affect grazer abundance directly, it significantly reduced the grazing efficiency of amphipods on blades of M. pyrifera. Our study illustrates how density- and trait-mediated interactions reduce grazer efficiency and provide potential indirect benefits to primary producers. To our knowledge, this is the first experimental evidence of a potential trophic cascade in kelp beds generated by consumptive and nonconsumptive effects. When considered alongside results of other studies that highlight positive effects of macroalgae on reef fish demographic rates, our results provide compelling evidence that mutualistic relationships may exist between kelp and associated predatory fishes. © Inter-Research 2010.

Planktivorous fish positively select Daphnia bearing advanced embryos

2020 ◽  
Vol 71 (4) ◽  
pp. 505 ◽  
Author(s):  
Jana Zemanová ◽  
Michal Šorf ◽  
Josef Hejzlar ◽  
Vanda Šorfová ◽  
Jaroslav Vrba
Keyword(s):  
Body Length ◽  
Life History Traits ◽  
Developmental Stages ◽  
Fish Predation ◽  
Lower Proportion ◽  
Planktivorous Fish ◽  
Top Down ◽  
Selective Elimination ◽  
Fish Predators ◽  
Food Conditions

The top-down effect of fish predation on reproduction success of Daphnia females was investigated in an outdoor mesocosm experiment with natural (oligotrophic) food conditions. The planktivorous fish, sunbleak (Leucaspius delineatus, 4.9 individuals m–3) was introduced into a half of mesocosms after the first sampling of zooplankton to compare daphnid life-history traits with and without fish predators. Our results showed selective fish predation on the daphnid females with advanced developmental stages of embryos. The Daphnia populations exposed to fish exhibited a lower proportion of females with advanced embryos over those with earlier embryonal stages. Fish predators obviously were attracted to more visible females bearing larger embryos, with well-developed pigmented eyes. Simultaneously, we found a smaller daphnid body length in the mesocosms with fish than in those that were fishless. However, the daphnid clutch size did not reflect their body-length pattern and, surprisingly, decreased regardless of fish presence or absence since the first sampling day, probably owing to deterioration of food quality (mean seston carbon:phosphorus ratio ~238). Nevertheless, this selective elimination of the females with advanced embryos, together with the overall decrease in daphnid fitness, can strengthen the deceleration of its population growth under fish predation.

A History Of Fire At Hitchcock Nature Center, Western Iowa, Reconstructed Through An Analysis Of Macroscopic Charcoal And Soil-Magnetic Properties

2020 ◽  
Vol 127 (1-4) ◽  
pp. 13-22
Author(s):  
Christoph E. Geiss ◽  
Nicole E. Towner
Keyword(s):  
Magnetic Properties ◽  
Parent Material ◽  
Recent Sediment ◽  
Radiocarbon Dates ◽  
Loess Hills ◽  
Modern Soil ◽  
Soil Site ◽  
History Of ◽  
Shell Fragments ◽  
Macroscopic Charcoal

We analyzed soil-magnetic properties and macroscopic charcoal abundances for two soil profiles located in Hitchcock Nature Center (HNC), Honey Creek, Iowa. Both profiles are located on valley bottoms in the Loess Hills of western Iowa and developed in redeposited Peoria loess. Site HNC 15D is located on an elevated stream terrace and contains a moderately well-developed modern soil. Site HNC 15G is located on a valley floor and consists of a poorly developed modern soil and a series of buried soil horizons. Both sites record consistently low charcoal concentrations of 0.5 mm2/g in prehistoric deposits. While site HNC 15D remains undated, age control at site HNC 15G is provided through four radiocarbon dates from charcoal and snail shell fragments. At site HNC 15G, late 19th century deposits are characterized by a marked increase in charcoal abundance to 3 mm2/g and charcoal abundances return to near prehistoric levels in recent sediment. We observe a similar increase in charcoal abundances below the modern soil at HNC 15D and an accumulation of charcoal at the surface of the profile. Soil-magnetic properties show moderate increases in magnetic susceptibility and ARM/IRM ratios when compared to loessic parent material and confirm moderate to weak soil development. High values for χARM/χFD (40-100) and χARM/χ (2-5) further suggest that regional fires have not been intense enough to significantly heat the topsoil horizons and allow for the formation of strongly magnetic secondary iron-oxide minerals.

Rubber Bonding

1950 ◽  
Vol 23 (4) ◽  
pp. 945-971
Author(s):  
J. M. Buist ◽  
W. J. S. Naunton
Keyword(s):  
Subject Matter ◽  
Early History ◽  
Physical Factors ◽  
History Of ◽  
Active Condition ◽  
The Subject ◽  
Service Conditions ◽  
Technical Interest ◽  
Brass Plating

Abstract Bonding in this paper is limited to the formation of bonds of considerable strength, and little attention is paid to the numerous agents which can be used for sticking rubber (usually cured rubber) to various materials. For many purposes a good stick, such as that obtained by the use of cyclized rubber, is sufficient, especially where service conditions tend to maintain the bond rather than to break it. Two other aspects of bonding, namely, bonding by brass-plating and the discussion of the nature of the bond do not enter into the subject matter of this paper. Brass-plating is a whole subject in itself, and is of technical interest only to those who have sufficient bonding work to maintain a plating unit in active condition. The question of whether a given bond is chemical or physical appears to the authors a futile controversy since, as with most rubber problems, both chemical and physical factors play their simultaneous parts. For the early history of the bonding of rubber to metals, the reader is referred to the paper by B. J. Habgood.

scholarly journals Density- and trait-mediated effects of fish predators on amphipod grazers: potential indirect benefits for the giant kelp Macrocystis pyrifera

2020 ◽  
Author(s):  
A Perez-Matus ◽  
Jeffrey Shima
Keyword(s):  
Grazing Pressure ◽  
Giant Kelp ◽  
Primary Producers ◽  
Secondary Importance ◽  
Predator Species ◽  
Indirect Benefits ◽  
Positive Effects ◽  
Behavioural Effects ◽  
Fish Predators ◽  
Predatory Fishes

Indirect effects of predators on primary producers may arise when predators suppress herbivore abundance and/or alter the behaviour patterns of herbivores in ways that reduce grazing pressure. Most studies highlight the role of predators in reducing herbivore abundance (i.e. density- mediated interactions), while behavioural effects (i.e. trait-mediated interactions) induced by predators are less commonly considered and are often assumed to be of secondary importance. We used a mesocosm experiment to evaluate the consumptive and behavioural effects of 2 species of predatory fishes on amphipod grazers that feed and nest on the giant kelp Macrocystispyrifera. Only one, Noto- labrus celidotus, of the 2 predator species reduced grazer abundance. Although the second predator species, N. fucicola, did not affect grazer abundance directly, it significantly reduced the grazing efficiency of amphipods on blades of M. pyrifera. Our study illustrates how density- and trait-mediated interactions reduce grazer efficiency and provide potential indirect benefits to primary producers. To our knowledge, this is the first experimental evidence of a potential trophic cascade in kelp beds generated by consumptive and nonconsumptive effects. When considered alongside results of other studies that highlight positive effects of macroalgae on reef fish demographic rates, our results provide compelling evidence that mutualistic relationships may exist between kelp and associated predatory fishes. © Inter-Research 2010.

scholarly journals The Overfishing Problem: Natural and Social Categories in Early Twentieth-Century Fisheries Science

2021 ◽  
Author(s):  
Gregory Ferguson-Cradler
Keyword(s):  
Twentieth Century ◽  
Recent Literature ◽  
Great Difficulty ◽  
Physical Factors ◽  
Social Categories ◽  
Political Factors ◽  
Fisheries Science ◽  
Early Twentieth Century ◽  
History Of ◽  
Political Economic

AbstractThis article looks at how fisheries biologists of the early twentieth century conceptualized and measured overfishing and attempted to make it a scientific object. Considering both theorizing and physical practices, the essay shows that categories and understandings of both the fishing industry and fisheries science were deeply and, at times, inextricably interwoven. Fish were both scientific and economic objects. The various models fisheries science used to understand the world reflected amalgamations of biological, physical, economic, and political factors. As a result, scientists had great difficulty stabilizing the concept of overfishing and many influential scholars into the 1930s even doubted the coherence of the concept. In light of recent literature in history of fisheries and environmental social sciences that critiques the infiltration of political and economic imperatives into fisheries and environmental sciences more generally, this essay highlights both how early fisheries scientists understood their field of study as the entire combination of interactions between political, economic, biological and physical factors and the work that was necessary to separate them.

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