scholarly journals Global ecomorphological restructuring of dominant marine reptiles prior to the K/Pg mass extinction

2022 ◽  
Author(s):  
Jamie A MacLaren ◽  
Rebecca F Bennion ◽  
Nathalie Bardet ◽  
Valentin Fischer
Keyword(s):  
Mass Extinction ◽  
Global Scale ◽  
Trophic Levels ◽  
Marine Food Webs ◽  
The North ◽  
Marine Reptiles ◽  
Community Restructuring ◽  
Notable Increase ◽  
Functional Capacities ◽  
Marine Reptile

Mosasaurid squamates were the dominant amniote predators in marine ecosystems during most of the Late Cretaceous. Evidence from multiple sites worldwide of a global mosasaurid community restructuring across the Campanian-Maastrichtian transition may have wide-ranging implications for the evolution of diversity of these top oceanic predators. In this study, we use a suite of biomechanical traits and functionally descriptive ratios to investigate how the morphofunctional disparity of mosasaurids evolved through time and space prior to the Cretaceous-Palaeogene (K/Pg) mass extinction. Our results suggest that the worldwide taxonomic turnover in mosasaurid community composition from Campanian to Maastrichtian is reflected by a notable increase in morphofunctional disparity on a global scale, but especially driven the North American record. Ecomorphospace occupation becomes more polarised during the late Maastrichtian, as the morphofunctional disparity of mosasaurids plateaus in the Southern Hemisphere and decreases in the Northern Hemisphere. We show that these changes are not associated with strong modifications in mosasaurid size, but rather with the functional capacities of their skulls, and that mosasaurid morphofunctional disparity was in decline in several provincial communities before the K/Pg mass extinction. Our study highlights region-specific patterns of disparity evolution, and the importance of assessing vertebrate extinctions both globally and regionally. Ecomorphological differentiation in mosasaurid communities, coupled with declines in other formerly abundant marine reptile groups, indicates widespread restructuring of higher trophic levels in marine food webs was well underway when the K-Pg mass extinction took place.

Fisheries

2007 ◽  
Author(s):  
John R. Beddington ◽  
Geoffrey P. Kirkwood
Keyword(s):  
Trophic Level ◽  
Global Scale ◽  
Trophic Levels ◽  
Predatory Fish ◽  
Apex Predators ◽  
The North ◽  
The Mean ◽  
Mean Trophic Level ◽  
Global Statistics ◽  
United Nations Food

The depletion of fish stocks on a global scale is well documented. The United Nations Food and Agriculture Organisation collects statistics on fisheries from all states and, despite obvious shortcomings in the data, a clear picture has been available for some time. Garcia and Grainger (2005) have succinctly documented the position from the latest available date: in 2003, only 3% of stocks were underexploited and 26% moderately exploited, while 52% were fully exploited, 16% were overfished, 7% were depleted, and 1% were recovering from earlier depletion. These global statistics mask two important phenomena. The first, highlighted by Pauly et al. (1998), is that fisheries are increasingly focusing on species lower down in the food-web and the second, highlighted by Myers and Worm (2003, 2005), is that large predatory fish have been particularly reduced in abundance. Both of these analyses are somewhat flawed. In the case of Pauly et al. there are two problems: the first is that the metrics used for the mean trophic level are presented as simple numbers with no estimates of error or indeed sensitivity. In such a situation, the changes in mean trophic levels are hard to interpret, particularly where the mean trophic level changes by at most around 10% over four decades. The second problem has been highlighted by a recent paper by Essington et al. (2006). They point out that in the periods when according to the analysis of Pauly et al. the mean trophic level was declining, in most cases catches of apex predators and indeed all upper trophic levels increased (an exception is the North Atlantic). In the case of the Myers and Worm analysis, they used the catch per unit of effort (CPUE) as an index of abundance. As discussed later in this chapter, there are problems with this, but more importantly for some key apex predators, in particular large tunas, the CPUE declines in the early stages of the fishery, where catches are small, but remains relatively stable under a regime of much higher catches. In such a situation, the interpretation that the CPUE reflects changes in abundance is clearly problematic.

scholarly journals The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

2010 ◽  
Vol 278 (1716) ◽  
pp. 2274-2282 ◽  
Author(s):  
Shi-xue Hu ◽  
Qi-yue Zhang ◽  
Zhong-Qiang Chen ◽  
Chang-yong Zhou ◽  
Tao Lü ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Middle Triassic ◽  
Marine Ecosystem ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Marine Animals ◽  
Exceptional Preservation ◽  
Marine Reptiles ◽  
Biotic Recovery ◽  
Permian Mass Extinction

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

scholarly journals Marine reptiles and climates of the Jurassic and Cretaceous of Siberia

2019 ◽  
Vol 27 (4) ◽  
pp. 13-39
Author(s):  
M. A. Rogov ◽  
N. G. Zverkov ◽  
V. A. Zakharov ◽  
M. S. Arkhangelsky
Keyword(s):  
Late Jurassic ◽  
New Records ◽  
Time Interval ◽  
Eastern Siberia ◽  
Warm Climate ◽  
The North ◽  
Marine Reptiles ◽  
Seasonal Migrations ◽  
Marine Reptile

All available data on the Jurassic and Cretaceous climates of Siberia, based on isotope, palaeontological and lithological markers are summarized. Late Pliensbachian cooling, early Toarcian warming, followed by late Toarcian to Middle Jurassic cooling and long-term Late Jurassic warming are well-recognized. Gradual cooling started since the late Ryazanian and continued during the whole Early Cretaceous except the short early Aptian warming event. At the beginning of the Late Cretaceous climate became warmer with warming peak at the Cenomanian–Turonian transition. During the middle and late Turonian climate became colder. During the Coniacian–Campanian time interval climate became warmer, but at the end of the Campanian new cooling event occurred. New records of marine reptiles from the Toarcian, Kimmeridgian, Volgian and Santonian–Campanian of the north of Eastern Siberia are described. All data concerning marine reptile occurrences in the Jurassic and Cretaceous of Siberia are reviewed; these records (from 51 localities) are mostly located at high palaeolatitudes. The analysis has revealed that most of the localities containing fossil reptile remains were llocated in the Transpolar palaeolatitudes (70°–87°). There are no direct relationship between climate oscillations and distribution of these animals. Taking into account recent data arguing that nearly all groups of the Jurassic and Cretaceous big marine reptiles were able to maintain constant body temperature and also were capable make long-range seasonal migrations, any conclusions concerning usage of these animals as markers of warm climate should be treated with a caution.

scholarly journals On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ndague Diogoul ◽  
Patrice Brehmer ◽  
Hervé Demarcq ◽  
Salaheddine El Ayoubi ◽  
Abou Thiam ◽  
...  
Keyword(s):  
Multiple Stressors ◽  
Marine Ecosystem ◽  
Trophic Levels ◽  
Sea Surface ◽  
Relative Index ◽  
Upwelling System ◽  
The North ◽  
Latitudinal Shift ◽  
Large Marine Ecosystem ◽  
North And South

AbstractThe resistance of an east border upwelling system was investigated using relative index of marine pelagic biomass estimates under a changing environment spanning 20-years in the strongly exploited southern Canary Current Large marine Ecosystem (sCCLME). We divided the sCCLME in two parts (north and south of Cap Blanc), based on oceanographic regimes. We delineated two size-based groups (“plankton” and “pelagic fish”) corresponding to lower and higher trophic levels, respectively. Over the 20-year period, all spatial remote sensing environmental variables increased significantly, except in the area south of Cap Blanc where sea surface Chlorophyll-a concentrations declined and the upwelling favorable wind was stable. Relative index of marine pelagic abundance was higher in the south area compared to the north area of Cap Blanc. No significant latitudinal shift to the mass center was detected, regardless of trophic level. Relative pelagic abundance did not change, suggesting sCCLME pelagic organisms were able to adapt to changing environmental conditions. Despite strong annual variability and the presence of major stressors (overfishing, climate change), the marine pelagic ressources, mainly fish and plankton remained relatively stable over the two decades, advancing our understanding on the resistance of this east border upwelling system.

scholarly journals Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction

2018 ◽  
Vol 4 (10) ◽  
pp. eaat5091 ◽  
Author(s):  
Haijun Song ◽  
Paul B. Wignall ◽  
Alexander M. Dunhill
Keyword(s):  
Time Scales ◽  
Carrying Capacity ◽  
Mass Extinction ◽  
Marine Species ◽  
Taxonomic Diversity ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Top Down ◽  
Structure Building

The Permian-Triassic mass extinction was the worst crisis faced by life; it killed >90% of marine species in less than 0.1 million years (Ma). However, knowledge of its macroecological impact over prolonged time scales is limited. We show that marine ecosystems dominated by non-motile animals shifted to ones dominated by nektonic groups after the extinction. In Triassic oceans, animals at high trophic levels recovered faster than those at lower levels. The top-down rebuilding of marine ecosystems was still underway in the latest Triassic, ~50 Ma after the extinction, and contrasts with the ~5-Ma recovery required for taxonomic diversity. The decoupling between taxonomic and ecological recoveries suggests that a process of vacant niche filling before reaching the maximum environmental carrying capacity is independent of ecosystem structure building.

scholarly journals Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments

2009 ◽  
Vol 6 (2) ◽  
pp. 267-274 ◽  
Author(s):  
H. Thomas ◽  
L.-S. Schiettecatte ◽  
K. Suykens ◽  
Y. J. M. Koné ◽  
E. H. Shadwick ◽  
...  
Keyword(s):  
North Sea ◽  
Co2 Storage ◽  
Global Scale ◽  
Coastal Sediments ◽  
Total Alkalinity ◽  
Co2 Uptake ◽  
Marginal Seas ◽  
The North ◽  
The North Sea ◽  
Ocean Carbon

Abstract. The coastal ocean is a crucial link between land, the open ocean and the atmosphere. The shallowness of the water column permits close interactions between the sedimentary, aquatic and atmospheric compartments, which otherwise are decoupled at long time scales (≅ 1000 yr) in the open oceans. Despite the prominent role of the coastal oceans in absorbing atmospheric CO2 and transferring it into the deep oceans via the continental shelf pump, the underlying mechanisms remain only partly understood. Evaluating observations from the North Sea, a NW European shelf sea, we provide evidence that anaerobic degradation of organic matter, fuelled from land and ocean, generates total alkalinity (AT) and increases the CO2 buffer capacity of seawater. At both the basin wide and annual scales anaerobic AT generation in the North Sea's tidal mud flat area irreversibly facilitates 7–10%, or taking into consideration benthic denitrification in the North Sea, 20–25% of the North Sea's overall CO2 uptake. At the global scale, anaerobic AT generation could be accountable for as much as 60% of the uptake of CO2 in shelf and marginal seas, making this process, the anaerobic pump, a key player in the biological carbon pump. Under future high CO2 conditions oceanic CO2 storage via the anaerobic pump may even gain further relevance because of stimulated ocean productivity.

scholarly journals Metabarcoding reveals different zooplankton communities in northern and southern areas of the North Sea

2020 ◽  
Author(s):  
Jan Niklas Macher ◽  
Berry B. van der Hoorn ◽  
Katja T. C. A. Peijnenburg ◽  
Lodewijk van Walraven ◽  
Willem Renema
Keyword(s):  
North Sea ◽  
Zooplankton Community ◽  
Taxonomic Diversity ◽  
Molecular Techniques ◽  
Trophic Levels ◽  
List Type ◽  
The North ◽  
Shelf Sea ◽  
The North Sea ◽  
Zooplankton Communities

AbstractZooplankton are key players in marine ecosystems, linking primary production to higher trophic levels. The high abundance and high taxonomic diversity renders zooplankton ideal for biodiversity monitoring. However, taxonomic identification of the zooplankton assemblage is challenging due to its high diversity, subtle morphological differences and the presence of many meroplanktonic species, especially in coastal seas. Molecular techniques such as metabarcoding can help with rapid processing and identification of taxa in complex samples, and are therefore promising tools for identifying zooplankton communities. In this study, we applied metabarcoding of the mitochondrial cytochrome c oxidase I gene to zooplankton samples collected along a latitudinal transect in the North Sea, a shelf sea of the Atlantic Ocean. Northern regions of the North Sea are influenced by inflow of oceanic Atlantic waters, whereas the southern parts are characterised by more coastal waters. Our metabarcoding results indicated strong differences in zooplankton community composition between northern and southern areas of the North Sea, particularly in the classes Copepoda, Actinopterygii (ray-finned fishes) and Polychaeta. We compared these results to the known distributions of species reported in previous studies, and by comparing the abundance of copepods to data obtained from the Continuous Plankton Recorder (CPR). We found that our metabarcoding results are mostly congruent with the reported distribution and abundance patterns of zooplankton species in the North Sea. Our results highlight the power of metabarcoding to rapidly assess complex zooplankton samples, and we suggest that the technique could be used in future monitoring campaigns and biodiversity assessments.HighlightsZooplankton communities are different in northern and southern areas of the North SeaMetabarcoding results are consistent with known species distributions and abundanceMetabarcoding allows for fast identification of meroplanktonic species

scholarly journals Microbial bioenergetics of coral-algal interactions

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3423 ◽  
Author(s):  
Ty N.F. Roach ◽  
Maria L. Abieri ◽  
Emma E. George ◽  
Ben Knowles ◽  
Douglas S. Naliboff ◽  
...  
Keyword(s):  
Power Output ◽  
Energy Use ◽  
Human Impacts ◽  
Global Scale ◽  
Trophic Levels ◽  
Maximal Power Output ◽  
Bioenergetic Analysis ◽  
Lower Oxygen ◽  
Thermodynamic Mechanism ◽  
Oxygen Concentrations

Human impacts are causing ecosystem phase shifts from coral- to algal-dominated reef systems on a global scale. As these ecosystems undergo transition, there is an increased incidence of coral-macroalgal interactions. Mounting evidence indicates that the outcome of these interaction events is, in part, governed by microbially mediated dynamics. The allocation of available energy through different trophic levels, including the microbial food web, determines the outcome of these interactions and ultimately shapes the benthic community structure. However, little is known about the underlying thermodynamic mechanisms involved in these trophic energy transfers. This study utilizes a novel combination of methods including calorimetry, flow cytometry, and optical oxygen measurements, to provide a bioenergetic analysis of coral-macroalgal interactions in a controlled aquarium setting. We demonstrate that the energetic demands of microbial communities at the coral-algal interaction interface are higher than in the communities associated with either of the macroorganisms alone. This was evident through higher microbial power output (energy use per unit time) and lower oxygen concentrations at interaction zones compared to areas distal from the interface. Increases in microbial power output and lower oxygen concentrations were significantly correlated with the ratio of heterotrophic to autotrophic microbes but not the total microbial abundance. These results suggest that coral-algal interfaces harbor higher proportions of heterotrophic microbes that are optimizing maximal power output, as opposed to yield. This yield to power shift offers a possible thermodynamic mechanism underlying the transition from coral- to algal-dominated reef ecosystems currently being observed worldwide. As changes in the power output of an ecosystem are a significant indicator of the current state of the system, this analysis provides a novel and insightful means to quantify microbial impacts on reef health.

Deep-Sea Faunal Zonation of Benthos along Beaufort-Bermuda Transect in the North-western Atlantic

1972 ◽  
Vol 73 ◽  
pp. 183-194 ◽  
Author(s):  
Robert Y. George ◽  
Robert J. Menzies
Keyword(s):  
Deep Sea ◽  
Abiotic Factors ◽  
Global Scale ◽  
Species Level ◽  
Red Clay ◽  
Generic Level ◽  
Western Atlantic ◽  
The North ◽  
Shelf Slope ◽  
Abyssal Zone

SynopsisIn this paper the subject of faunal zonation in the ocean floor from the intertidal, and over the continental shelf, slope and rise and to the abyssal plain is examined on the basis of faunal change at the generic and species level. The region investigated over a period of five years aboard R/V Eastward is a Beaufort-Bermuda transect, approximately 75 kilometres wide and 500 kilometres long and bounded between 32° and 36°N latitude and 64° and 79°W longitude. A new method, involving numerical indices reflecting changes in the composition of taxa, endemism and diversity between adjacent depth levels, was developed for defining faunal boundaries. Isotherms and isobaths utilised by earlier authors for characterising deep-sea boundary on a global scale do not coincide with natural faunal boundaries. This study analyses the vertical distribution of 128 species of isopod crustaceans and 28 species of large epibenthic invertebrates. The zonation patterns seem to correspond with correlations in environmental conditions such as currents, topography and sediments.We suggest four major vertical faunal provinces, characterised at the generic level, namely (1) the Intertidal Faunal Province; (2) the Shelf Faunal Province; (3) the Archibenthal Zone of Transition; and (4) the Abyssal Faunal Province and internal zones within these characterised at the species level. The main aspects of interest include the presence of a narrow ‘meso abyssal zone’ with a species maximum, the demonstration of the true transitional nature of the Archibenthal Zone in biotic and abiotic factors and the characteristic low-biomass Red Clay environment showing definite faunal isolation from the continental margin.

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