Low predation intensity on the stalked crinoid Democrinus sp. (Echinodermata) in Roatán, Honduras reveals deep water as likely predation refuge

2020 ◽  
Author(s):  
Margaret A Veitch ◽  
Tomasz K Baumiller
Keyword(s):  
Deep Water ◽  
Ecological History ◽  
Quantitative Estimates ◽  
Predation Intensity ◽  
Longitudinal Approach ◽  
Manned Submersible ◽  
History Of ◽  
Stalked Crinoids ◽  
High Predation ◽  
Predation Refuge

Predation has been hypothesized to play a key role in the evolutionary and ecological history of crinoids. Whereas evidence of predation on crinoids in the form of injuries can be common, quantifying predation intensity, which is critical for properly evaluating such hypotheses, has proven challenging. Here, we used a longitudinal approach to quantify predation intensity on the extant, deep-water, stalked crinoid, Democrinus sp. The quantitative estimates are based on data collected from a manned submersible during expeditions conducted over a 3-yr span. These results indicate that this deep-water crinoid is subject to much lower predation intensity than are crinoids living in shallow water, consistent with (1) an inverse relationship between predation intensity and depth, and (2) the hypothesis that for stalked crinoids, which are unable to handle high predation intensity, deep water is a refugium.

Can Radiocarbon Records lead to Quantitative Estimates of Deep-Ocean Ventilation Rates with Error Estimates in the Geologic Past?

2020 ◽  
Author(s):  
Olivier Marchal ◽  
Ning Zhao ◽  
Faith Duffy
Keyword(s):  
Least Squares ◽  
Error Estimates ◽  
Deep Water ◽  
Benthic Foraminifera ◽  
Deep Ocean ◽  
The Past ◽  
Ocean Ventilation ◽  
Quantitative Estimates ◽  
History Of ◽  
Ventilation Rates

<p>Over the past two decades, an impressive amount of radiocarbon age measurements on samples of fossil benthic foraminifera and deep-sea corals have been published in the literature. These measurements are commonly used to draw inferences about changes in the ventilation of deep oceanic basins during the last deglacial period. Lacking in most previous studies, however, are quantitative estimates of deep-ocean paleo-ventilation rates and quantitative estimates of their errors, leading to potential over-interpretation and sterile debate. Moreover, most previous studies were concerned with the interpretation of individual records with low or no regard for other records available for the same time interval.</p><p>Here we present an effort to go beyond the qualitative interpretation of single radiocarbon records by analyzing an updated compilation of <sup>14</sup>C age data using recursive least-squares (RLS) methods (a Kalman filter and a related smoother). In stark contrast with other methods of data analysis, RLS methods can provide an estimate of the history of the state of the physical system of interest and an estimate of the error in this history, which are consistent (in the least-squares sense) with times series of data and with a dynamical model, given estimates of the statistics of the errors in the data and in the model. Our current compilation includes 1,698 deep water <sup>14</sup>C age data for the past 40 kyr based on fossil samples of benthic foraminifera, deep‐sea corals, deep‐dwelling planktonic foraminifera, bivalves, and spiral shells. The geographic distribution of the samples is very irregular, with most of them originating from near the margins and with large regions devoid of any data. The depths of the samples vary from about 250 m to about 5,000 m. In our study, the potential of RLS methods to estimate the history of deep-ocean ventilation rates and their errors from deep water <sup>14</sup>C age data is explored for a number of abyssal layers in the Atlantic Ocean during the deglacial interval from 20 to 10 kyr BP. The approach used to apply the powerful but computationally expensive RLS methods to the analysis of geologic time series is described, the least-squares estimates of ventilation rate history in different layers are reported, and their significance in the light of their error estimates is discussed.</p>

Is predation intensity reduced with increasing depth? Evidence from the west Atlantic stalked crinoidEndoxocrinus parrae(Gervais) and implications for the Mesozoic marine revolution

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 339-351 ◽  
Author(s):  
Tatsuo Oji
Keyword(s):  
Shallow Water ◽  
The Other ◽  
The West ◽  
Bathymetric Range ◽  
Late Mesozoic ◽  
Predation Intensity ◽  
Stalked Crinoids ◽  
The Caribbean ◽  
Mesozoic Marine Revolution ◽  
Sublethal Predation

The number of regenerated arms was counted on specimens of two distinct phenotypes of the stalked crinoidEndoxocrinus parrae(Gervais) from a wide bathymetric range in the Caribbean (178-723 m). In one phenotype, the sample was divided into two groups, one from shallower (< 500 m) depths, the other from deeper (≥ 500 m); in the other phenotype the group divided at 550 m. In both phenotypes, the frequency of regenerated arms is significantly higher in specimens from shallower water than in those from deeper water. If the regenerated arms inEndoxocrinus parraewere the result of sublethal predation, as previously suggested, then predation intensity is higher in shallow water than deep water. These results are consistent with the idea of the late Mesozoic marine revolution—that there has been stronger predation on various invertebrates in shallow-water environments since the late Mesozoic. The stalked crinoids may have been unable to cope with increased predation in shelf environments, and they migrated to offshore environments.

This Fissured Land: An Ecological History of India.

1995 ◽  
Vol 68 (1) ◽  
pp. 131 ◽  
Author(s):  
Eva Cheung Robinson ◽  
Madhav Gadgil ◽  
Ramachandra Guha
Keyword(s):  
Ecological History ◽  
History Of

Comparative analysis of the fatty acid composition of deep-water Baikal amphipods

Crustaceana ◽  
2019 ◽  
Vol 92 (1) ◽  
pp. 57-72
Author(s):  
Selmeg V. Bazarsadueva ◽  
Larisa D. Radnaeva ◽  
Arnold K. Tulokhonov
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Lake Baikal ◽  
Deep Water ◽  
Monounsaturated Fatty Acids ◽  
Manned Submersible ◽  
Main Fatty Acid ◽  
Low Levels

Abstract In this report, we have compared the fatty acid composition of the endemic Lake Baikal amphipods Ommatogammarus albinus (Dybowsky, 1874) and Parapallasea lagowskii (Dybowsky, 1874). Specimens were sampled using the deep-water manned submersible “Mir” at the oil-methane seeps of Cape Gorevoy Utes and at a hydrothermal vent in Frolikha Bay. High levels of monounsaturated fatty acids and relatively low levels of saturated and polyunsaturated fatty acids were detected in the studied amphipods, with oleic and palmitic acid representing the main fatty acid components. The habitat of the amphipods exerted a profound effect on their fatty acid profile: the amphipods of Gorevoy Utes contained higher levels of linolenic 18:3n3 and arachidonic 20:4n6 acids, while the amphipods of Frolikha Bay contained higher levels of eicosapentaenoic 20:5n3 and docosahexaenoic 22:6n3 acid. Based on these findings, we suggest that the amphipods’ diet in different areas of Lake Baikal determines their fatty acid composition.

Degraded or Just Dusty? Examining Ecological Change in Arid Lands

BioScience ◽  
2019 ◽  
Vol 69 (7) ◽  
pp. 508-522
Author(s):  
Jennifer L Silcock ◽  
Rod J Fensham
Keyword(s):  
Historical Record ◽  
Rangeland Management ◽  
Rare Plant ◽  
Ecological Change ◽  
Remote Areas ◽  
Comprehensive Management ◽  
Ecological History ◽  
Abrupt Changes ◽  
History Of

AbstractThe ecological history of rangelands is often presented as a tale of devastation, where fragile drylands are irreversibly degraded through inappropriate land use. However, there is confusion about how to recognize and measure degradation, especially in low-productivity environments characterized by extreme natural variability and where abrupt and comprehensive management upheavals preclude benchmarks. These issues have important consequences for rangeland management programs, which are typically founded on presumptions of substantial and ongoing degradation from former “natural” states. We explore complementary approaches to critically assess degradation: the historical record, long-term grazing exclosures, surveys for potentially rare and sensitive plant species, and assessment of water-remote areas in relation to rare plant occurrence. Employing these approaches in inland Australia, we show that prevailing paradigms have become entrenched despite being inconsistent with empirical evidence. Our methodology can be applied to drylands with abrupt changes in management and contentious ecological narratives.

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