The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

Abstract

The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans.

Environmental controls on Jurassic marine ecosystems during global warming

“…3D; Table DR1). The most important variable is, however, d 98/95 Mo, which alone explains almost 40% of the total variation ( Table 1), confirming that in the Jurassic, as in the present day (Diaz and Rosenberg, 2008), dissolved oxygen was a critical control on benthic marine ecosystems (e.g., Danise et al, 2013, and references therein).…”

“…Ordination of the pre-extinction benthic data resembles that of the environmental data (Fig. 3B), indicating pre-extinction stability followed by turnover at the top of the semicelatum Subzone, where diverse benthic communities occupying a variety of infaunal and epifaunal trophic niches (Danise et al, 2013) are replaced by monospecific assemblages of the epifaunal suspension-feeding bivalve Bositra radiata ("extinction interval", Fig. 2).…”

“…Lithology was 1 GSA Data Repository item 2015096, Figure DR1 (detailed stratigraphic log), Figure DR2 (detail of PCoA plots), on March 18, 2015 geology.gsapubs.org Downloaded from added as a categorical variable recording facies and sea-level changes. A high-resolution paleontological data set was assembled from the benthic macroinvertebrate quantitative abundance data of Danise et al (2013), integrated with quantitative nektonic data from the same horizons and collected with the same methods (Appendix DR1; Fig. DR1).…”

Effects of hypoxia in the gills of the Manila clam Ruditapes philippinarum using NMR-based metabolomics

“…Hypoxification of the regional marine environment not only triggers a habitat loss for local marine organisms, reducing marine biological population, and altering the structure and function of marine ecosystem, but also interferes with the global biogeochemical cycling process (Deutsch et al, 2011). Impacts of marine hypoxia start from the sediment-water interface, causing a mass mortality of macrobenthos (Danise et al, 2013;Montagna & Ritter, 2006). Exposed to hypoxia, marine organisms may develop multiple physiological defects in respiration, metabolism, growth, and reproduction.…”

Oxygen microprofile in the prepared sediments and its implication for the sediment oxygen consuming process in a heavily polluted river of China

“…Besides, the sediment oxygen consumption is closely related to the benthic habitat condition. The existence of benthic invertebrates may influence the sediment oxygen-consuming process (Ferguson et al 2013), and the sediment oxygen content can also effect the distribution of these benthic community (Danise et al 2013).…”