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Thesis
Peer Reviewed

Climate and food supply influences on mobile epibenthic megafauna populations in the abyssal NE Pacific from 1989 to 2004

Ruhl, Henry A.

UC San Diego Electronic Theses and Dissertations (2006)

The effects of climate on abyssal megafaunal populations is largely unknown. Photo-transecting techniques have been used at a long-term abyssal study site in the NE Pacific to examine the population dynamics of mobile echinoderms on a roughly seasonal basis from 1989-2004. At 4,100 m depth, these animals live in a relatively stable environment with no light and relatively invariant temperatures. The primary habitat variables at the site are the quantity and quality of the particulate organic carbon (POC) that sinks from the surface waters above. Significant time-lagged correlations indicate that climatic variations related to the El Ni̋no Southern Oscillation can influence surface ocean productivity and the amount of POC that is exported to the abyssal benthos. All of the ten most dominant fauna at the site had order of magnitude or greater fluctuations in abundance with the most prominent differences occurring between 1989-1998 and 2001-2004. Increases in abundance were often linked to increases in smaller individuals suggesting that population fluctuations were the result of recruitment, biological interactions, and mortality. Significant correlations also exist between changes in the POC food supply and the abundance of several mobile megafauna with measurable changes in abundance lagging changes in food supply by 6 or more months. Some species, such as the holothuroid Elpidia minutissima, increased in abundance during periods of low food supply while other echinoderms thrived during periods of higher food flux. A three-term local quadrat variance technique was employed to examine dispersion and found few aggregations that might bias the abundance estimates presented. A significant shift in megafauna community structure occurred between the 1989- 1998 and 2001-2004 periods. An analysis of the rank abundance distributions of megafauna indicated that the overall species dominance changed between the two periods. This shift in equitability was also linked to the POC flux further indicating that these animals have differential responses to the food supply. This and other long-term research have indicated that interannual-scale climatic fluctuations could be influencing abyssal populations thousands of meters beneath the ocean surface

Article

Climate and food supply influences on mobile epibenthic megafauna populations in the abyssal NE Pacific from 1989 to 2004

Ruhl, Henry A

Scripps Institution of Oceanography Technical Report (2006)

The effects of climate on abyssal megafaunal populations are largely unknown. Photo-transecting techniques have been used at a long-term abyssal study site in the NE Pacific to examine the population dynamics of mobile echinoderms on a roughly seasonal basis from 1989-2004. At 4,100 m depth, these animals live in a relatively stable environment with no light and relatively invariant temperatures. The primary habitat variables at the site are the quantity and quality of the particulate organic carbon (POC) that sinks from the surface waters above. Significant time-lagged correlations indicate that climatic variations related to the El Niño Southern Oscillation can influence surface ocean productivity and the amount of POC that is exported to the abyssal benthos.

All of the ten most dominant fauna at the site had order of magnitude or greater fluctuations in abundance with the most prominent differences occurring between 1989-1998 and 2001-2004. Increases in abundance were often linked to increases in smaller individuals suggesting that population fluctuations were the result of recruitment, biological interactions, and mortality. Significant correlations also exist between changes in the POC food supply and the abundance of several mobile megafauna with measurable changes in abundance lagging changes in food supply by 6 or more months. Some species, such as the holothuroid Elpidia minutissima, increased in abundance during periods of low food supply while other echinoderms thrived during periods of higher food flux.

One assumption of the line-transect methodology used here is that non-random aggregations are not present at scales or patterns that might bias density estimates. To help verify this assumption a three-term local quadrat variance technique was employed and found few aggregations that might bias the abundance estimates presented. A significant shift in megafauna community structure occurred between the 1989-1998 and 2001-2004 periods. An analysis of the rank abundance distributions of megafauna indicated that the overall species dominance changed between the two periods. This shift in equitability was also linked to the POC flux further indicating that these animals have differential responses to the food supply. This and other longterm research have indicated that interannual-scale climatic fluctuations could be influencing abyssal populations thousands of meters beneath the ocean surface.

Article
Peer Reviewed

Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century

UC San Diego Previously Published Works (2013)

Ongoing greenhouse gas emissions can modify climate processes and induce shifts in ocean temperature, pH, oxygen concentration, and productivity, which in turn could alter biological and social systems. Here, we provide a synoptic global assessment of the simultaneous changes in future ocean biogeochemical variables over marine biota and their broader implications for people. We analyzed modern Earth System Models forced by greenhouse gas concentration pathways until 2100 and showed that the entire world's ocean surface will be simultaneously impacted by varying intensities of ocean warming, acidification, oxygen depletion, or shortfalls in productivity. In contrast, only a small fraction of the world's ocean surface, mostly in polar regions, will experience increased oxygenation and productivity, while almost nowhere will there be ocean cooling or pH elevation. We compiled the global distribution of 32 marine habitats and biodiversity hotspots and found that they would all experience simultaneous exposure to changes in multiple biogeochemical variables. This superposition highlights the high risk for synergistic ecosystem responses, the suite of physiological adaptations needed to cope with future climate change, and the potential for reorganization of global biodiversity patterns. If co-occurring biogeochemical changes influence the delivery of ocean goods and services, then they could also have a considerable effect on human welfare. Approximately 470 to 870 million of the poorest people in the world rely heavily on the ocean for food, jobs, and revenues and live in countries that will be most affected by simultaneous changes in ocean biogeochemistry. These results highlight the high risk of degradation of marine ecosystems and associated human hardship expected in a future following current trends in anthropogenic greenhouse gas emissions.

Cover page: Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century

Article
Peer Reviewed

Global Observing Needs in the Deep Ocean

UC San Diego Previously Published Works (2019)

Article
Peer Reviewed

BioTIME: A database of biodiversity time series for the Anthropocene

UC Berkeley Previously Published Works (2018)

Motivation

The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

Main types of variables included

The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

Spatial location and grain

BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km² (158 cm²) to 100 km² (1,000,000,000,000 cm²).

Time period and grain

BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

Major taxa and level of measurement

BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Software format

.csv and .SQL.

Cover page: BioTIME: A database of biodiversity time series for the Anthropocene