scholarly journals A bottom-up perspective on ecosystem change in Mesozoic oceans

2016 ◽  
Vol 283 (1841) ◽  
pp. 20161755 ◽  
Author(s):  
Andrew H. Knoll ◽  
Michael J. Follows
Keyword(s):  
Secular Trends ◽  
Trophic Levels ◽  
Ecosystem Change ◽  
Molecular Clocks ◽  
Phytoplankton Composition ◽  
Marine Animals ◽  
Environmental Distribution ◽  
Major Shift ◽  
Early Cenozoic ◽  
Biomarker Molecules

Mesozoic and Early Cenozoic marine animals across multiple phyla record secular trends in morphology, environmental distribution, and inferred behaviour that are parsimoniously explained in terms of increased selection pressure from durophagous predators. Another systemic change in Mesozoic marine ecosystems, less widely appreciated than the first, may help to explain the observed animal record. Fossils, biomarker molecules, and molecular clocks indicate a major shift in phytoplankton composition, as mixotrophic dinoflagellates, coccolithophorids and, later, diatoms radiated across shelves. Models originally developed to probe the ecology and biogeography of modern phytoplankton enable us to evaluate the ecosystem consequences of these phytoplankton radiations. In particular, our models suggest that the radiation of mixotrophic dinoflagellates and the subsequent diversification of marine diatoms would have accelerated the transfer of primary production upward into larger size classes and higher trophic levels. Thus, phytoplankton evolution provides a mechanism capable of facilitating the observed evolutionary shift in Mesozoic marine animals.

scholarly journals Plant Invasion Has Limited Impact on Soil Microbial α-Diversity: A Meta-Analysis

Diversity ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 112
Author(s):  
Gordon F. Custer ◽  
Linda T. A. van Diepen
Keyword(s):  
Microbial Diversity ◽  
Plant Invasion ◽  
Meta Analysis ◽  
Agricultural Practices ◽  
Nutrient Status ◽  
Trophic Levels ◽  
Ecosystem Change ◽  
Soil Microbial Diversity ◽  
Soil Microbial ◽  
Α Diversity

Plant invasion has proven to be a significant driver of ecosystem change, and with the increased probability of invasion due to globalization, agricultural practices and other anthropogenic causes, it is crucial to understand its impact across multiple trophic levels. With strong linkages between above and belowground processes, the response of soil microorganisms to plant invasion is the next logical step in developing our conceptual understanding of this complex system. In our study, we utilized a meta-analytical approach to better understand the impacts of plant invasion on soil microbial diversity. We synthesized 70 independent studies with 23 unique invaders across multiple ecosystem types to search for generalizable trends in soil microbial α-diversity following invasion. When possible, soil nutrient metrics were also collected in an attempt to understand the contribution of nutrient status shifts on microbial α-diversity. Our results show plant invasion to have highly heterogenous and limited impacts on microbial α-diversity. When taken together, our study indicates soil microbial α-diversity to remain constant following invasion, contrary to the aboveground counterparts. As our results suggest a decoupling in patterns of below and aboveground diversity, future work is needed to examine the drivers of microbial diversity patterns following invasion.

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 A millennium of trophic stability in Atlantic cod (Gadus morhua): transition to a lower and converging trophic niche in modern times

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guðbjörg Ásta Ólafsdóttir ◽  
Ragnar Edvardsson ◽  
Sandra Timsic ◽  
Ramona Harrison ◽  
William P. Patterson
Keyword(s):  
Trophic Ecology ◽  
Atlantic Cod ◽  
Marine Ecosystem ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Trophic Levels ◽  
Bone Collagen ◽  
Predatory Fish ◽  
Ecosystem Change ◽  
Data Set

AbstractStable isotope analyses of zooarchaeological material can be used to examine ecological variability in exploited species at centennial to millennial scales. Climate change is a notable driver of marine ecosystem change, although historical fishing is also likely to have impacted past marine systems. Fishing removes the oldest and largest individuals and may thereby result in shorter trophic pathways and reduced niche width of predatory fish species. In the current study we examine the trophic niche of Atlantic cod, haddock and Atlantic wolffish, in the last millennium using δ13C and δ15N values of bone collagen. We report a lower trophic level of Atlantic cod and haddock but higher level of wolffish in present times, following centuries at consistent and higher trophic levels of Atlantic cod. This results in a concurrent converging trophic niche of the demersal fish. We suggest that the current data set provides a valuable historical baseline facilitating interpretation of current variability in the trophic ecology of northern demersal fish.

Arsenic distribution and species in two Zostera capricorni seagrass ecosystems, New South Wales, Australia

2011 ◽  
Vol 8 (1) ◽  
pp. 9 ◽  
Author(s):  
William A. Maher ◽  
Simon D. Foster ◽  
Anne M. Taylor ◽  
Frank Krikowa ◽  
Elliot G. Duncan ◽  
...  
Keyword(s):  
Food Web ◽  
Nitrogen Isotopes ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Trophic Levels ◽  
Marine Animals ◽  
South Wales ◽  
Arsenic Distribution ◽  
Seagrass Ecosystems ◽  
Zostera Capricorni

Environmental context Arsenic concentrations and species were determined in seagrass ecosystems where the food web was established using carbon and nitrogen isotopes. There was a clear increase in the proportion of arsenobetaine in tissues of higher trophic level organisms, which is attributed to an increasing arsenobetaine content of the diet and the more efficient assimilation and retention of arsenobetaine over other arsenic species. The results provide an explanation for the prominence of arsenobetaine in higher marine animals. Abstract Arsenic concentrations and species were compared in biota from two Zostera capricorni ecosystems. Mean arsenic concentrations were not significantly different for non‐vegetative sediment, rhizosphere sediment, Z. capricorni blades, roots, rhizomes, epiphytes, amphipods, polychaetes, molluscs, crustaceans and fish, but were significantly different in detritus. Sediments and plant tissues contained mostly inorganic arsenic and PO4–arsenoriboside. Detritus contained mostly PO4–arsenoriboside. Fish tissues contained predominately arsenobetaine. Other animals had lower proportions of arsenobetaine and variable quantities of minor arsenic species. Bioconcentration but not biomagnification of arsenic is occurring with no evidence of arsenic hyper accumulation. The proportion of arsenobetaine increases through the food web and is attributed to a shift from a mixed diet at lower trophic levels to animals containing mostly arsenobetaine at higher trophic levels and the more efficient retention of arsenobetaine, compared to other arsenic species.

Among- and within-species variability in fatty acid signatures of marine fish and invertebrates on the Scotian Shelf, Georges Bank, and southern Gulf of St. Lawrence

2002 ◽  
Vol 59 (5) ◽  
pp. 886-898 ◽  
Author(s):  
Suzanne M Budge ◽  
Sara J Iverson ◽  
W Don Bowen ◽  
Robert G Ackman
Keyword(s):  
Fatty Acid ◽  
Stomach Contents ◽  
Trophic Levels ◽  
Species Variation ◽  
Georges Bank ◽  
Phytoplankton Composition ◽  
Scotian Shelf ◽  
Geographical Regions ◽  
Dietary Shifts ◽  
Fatty Acid Compositions

The fat and fatty acid compositions of 28 species of fish and invertebrates (n = 954) from the Scotian Shelf, Georges Bank, and the Gulf of St. Lawrence were determined. Discriminant analysis of the 16 most numerous species (n [Formula: see text] 18 each), using 17 major fatty acids, classified species with greater than 98% accuracy and grouped species into three general clusters (gadids, flatfish, and planktivores) with similar fatty acid compositions, and likely, similar diets. A number of species exhibited changes in fatty acid signatures with increasing size (multivariate analysis of variance), which corresponded with known dietary shifts reported from stomach contents analyses. Location effects were also observed among the three major geographical regions and were probably due to broad-scale variations in prey assemblages and phytoplankton composition in the northwestern Atlantic. Despite these effects, within-species variation was still substantially less than among-species variation. Thus, fatty acid signatures can be used to distinguish and characterize fish and invertebrate species in a given ecosystem, as well as to study finer-scale trophic interactions of these species. These data also have applications at higher trophic levels and will serve as a prey database for studying the diets of other fish and marine mammal predators using fatty acid signatures.

The bioaccumulation and effects of organochlorine pesticides in marine animals

1975 ◽  
Vol 189 (1096) ◽  
pp. 291-304 ◽  
Keyword(s):  
Organochlorine Pesticides ◽  
Sea Water ◽  
Insect Pests ◽  
Trophic Levels ◽  
Marine Animals ◽  
Marine Food Chain ◽  
Top Predators ◽  
Wide Range ◽  
Different Types ◽  
Marine Food

Organochlorine pesticides have been in use now for about 30 years. As a class of compounds they are not in general readily degradable and they can now be detected in a wide range of samples taken anywhere in the world, including the deep oceans. Organochlorine pesticides are highly fat soluble and it was discovered over 15 years ago that they were accumulated by several forms of life, especially the top predators. Since this discovery a great deal of effort has been spent in attempts to establish to what extent they affect organisms other than the target insect pests. This paper reviews the levels of various pesticides in the sea and the concentration found at different trophic levels in the marine food chain. The levels of accumulation relative to sea water are discussed, together with the known and potential effects that the accumulation levels might have on different types of organisms.

Predicting changes in distribution of a large coastal shark in the face of the strengthening East Australian Current

2020 ◽  
Vol 642 ◽  
pp. 163-177 ◽  
Author(s):  
Y Niella ◽  
AF Smoothey ◽  
V Peddemors ◽  
R Harcourt
Keyword(s):  
Austral Summer ◽  
Conservation Strategies ◽  
Limiting Factor ◽  
Commercial Fisheries ◽  
East Australian Current ◽  
Spatial And Temporal Patterns ◽  
Marine Animals ◽  
Factors Affecting ◽  
Southeastern Australia ◽  
The Face

In the face of accelerating climate change, conservation strategies will need to consider how marine animals deal with forecast environmental change as well as ongoing threats. We used 10 yr (2009-2018) of data from commercial fisheries and a bather protection program along the coast of New South Wales (NSW), southeastern Australia, to investigate (1) spatial and temporal patterns of occurrence in bull sharks and (2) environmental factors affecting bull shark occurrence along the coast of NSW. Predicted future distribution for this species was modelled for the forecast strengthening East Australian Current. Bull sharks were mostly harvested in small to larger estuaries, with average depth and rainfall responsible for contrasting patterns for each of the fisheries. There was an increase in the occurrence of bull sharks over the last decade, particularly among coastal setline fisheries, associated with seasonal availability of thermal gradients >22°C and both westward and southward coastal currents stronger than 0.15 and 0.60 m s-1, respectively, during the austral summer. Our model predicts a 3 mo increase in the availability of favourable water temperatures along the entire coast of NSW for bull sharks by 2030. This coastline provides a uniquely favourable topography for range expansion in the face of a southerly shift of warmer waters, and habitat is unlikely to be a limiting factor for bull sharks in the future. Such a southerly shift in distribution has implications for the management of bull sharks both in commercial fisheries and for mitigation of shark-human interactions.

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