How Sea Floor Ecosystems Are Damaged By, And Recover From, Abrupt Climate Change

A new study by Sarah Moffitt, Tessa Hill, Peter Roopnarine, and James Kennett (Response of seafloor ecosystems to abrubt global climate change) gets a handle on the effects of relatively rapid warming and associated Oxygen loss in the sea on invertebrate communities. The study looked at a recent warming event (the end of the last glacial) in order to understand the present warming event, which is the result of human-caused greenhouse gas pollution.

Here is what is unique about the study. A 30 foot deep core representing the time period from 3,400 to 16,100 year ago, was raised from a site in the pacific, and the researchers tried to identify and characterize all of the complex invertebrate remains in the core. That is not usually how it is done. Typically a limited number of species, and usually microscopic surface invertebrates (Foraminifera) only, are identified and counted. There are good reasons it is done that way. But the new study looks instead at non-single-celled invertebrates (i.e., clams and such) typically found at the bottom, not top, of the water column. This study identified over 5,400 fossils and trace fossils from Mollusca, Echinodermata, Arthropoda, and Annelida (clams, worms, etc.).

Complex invertebrates are important because of their high degree of connectivity in an ecosystem. In the sea, a clam, crab, or sea cucumber may be the canary in the proverbial coal mine. Study co-author Peter Roopnarine says, “The complexity and diversity of a community depends on how much energy is available. To truly understand the health of an ecosystem and the food webs within, we have to look at the simple and small as well as the complex. In this case, marine invertebrates give us a better understanding of the health of ecosystems as a whole.”

The most important finding of the study is this: the marine ecosystem sampled by this core underwent dramatic changes, including local extinctions, and took up to something like 1,000 years to recover from that. The amount of change in bottom ecosystems under these conditions was previously not well known, and the recovery rate was previously assumed to be much shorter, on the order of a century.

From the abstract of the paper:

Anthropogenic climate change is predicted to decrease oceanic oxygen (O2) concentrations, with potentially significant effects on marine ecosystems. Geologically recent episodes of abrupt climatic warming provide opportunities to assess the effects of changing oxygenation on marine communities. Thus far, this knowledge has been largely restricted to investigations using Foraminifera, with little being known about ecosystem-scale responses to abrupt, climate-forced deoxygenation. We here present high-resolution records based on the first comprehensive quantitative analysis, to our knowledge, of changes in marine metazoans … in response to the global warming associated with the last glacial to interglacial episode. The molluscan archive is dominated by extremophile taxa, including those containing endosymbiotic sulfur-oxidizing bacteria (Lucinoma aequizonatum) and those that graze on filamentous sulfur-oxidizing benthic bacterial mats (Alia permodesta). This record … demonstrates that seafloor invertebrate communities are subject to major turnover in response to relatively minor inferred changes in oxygenation (>1.5 to <0.5 mL·L−1 [O2]) associated with abrupt (<100 y) warming of the eastern Pacific. The biotic turnover and recovery events within the record expand known rates of marine biological recovery by an order of magnitude, from 1,000 y, and illustrate the crucial role of climate and oceanographic change in driving long-term successional changes in ocean ecosystems.

Lead author Sarah Moffitt, of the UC Davis Bodega Marine Laboratory and Coastal and Marine Sciences Institute notes, “In this study, we used the past to forecast the future. Tracing changes in marine biodiversity during historical episodes of warming and cooling tells us what might happen in years to come. We don’t want to hear that ecosystems need thousands of years to recover from disruption, but it’s critical that we understand the global need to combat modern climate impacts.”

There is a video:

Caption from the figure at the top of the post: Fig. 1. Core MV0811–15JC’s (SBB; 418 m water depth; 9.2 m core length; 34.37°N, 120.13°W) oxygen isotopic, foraminiferal, and metazoan deglacial record of the latest Quaternary. Timescale (ka) is in thousands of years before present, and major climatic events include the Last Glacial Maximum (LGM), the Bølling and Allerød (B/A), the Younger Dryas (YD), and the Holocene. (A) GISP2 ice core δ18O values (46). (B) Planktonic Foraminifera Globigerina bulloides δ18O values for core MV0811–15JC, which reflects both deglacial temperature changes in Eastern Pacific surface waters and changes in global ice volume. (C) Benthic foraminiferal density (individuals/cm3). (D) Relative frequency (%) of benthic Foraminifera with faunal oxygen-tolerance categories including oxic–mildly hypoxic (>1.5 mL·L−1 O2; N. labradorica, Quinqueloculina spp., Pyrgo spp.), intermediate hypoxia (1.5–0.5 mL·L−1 O2; Epistominella spp., Bolivina spp., Uvigerina spp.), and severe hypoxia (<0.5 mL·L−1 O2; N. stella, B. tumida) (19). (E) Log mollusc density (individuals/cm3). (F) Ophiuroids (brittle star) presence (presence = 1, absence = 0, 5-cm moving average). (G) Ostracod valve density (circles, valves/cm3) and 5-cm moving average.

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Over the years there have been countless studies surrounding the effects global warming has had on our oceans and the organisms that call it home. What I don't understand is why it is only now that we are looking at the effect it will have and has had on the more complex organisms? Surely if they are more connected to their environment and can give us a better idea of the potential consequences to their ecosystems, they should be some of the first organisms to be looked at?

By Keagan Loader … (not verified) on 31 Mar 2015 #permalink

The research on the effects of relatively rapid warming and associated oxygen loss in the sea on invertebrate communities is very interesting, but what about research on the present sea floor ecosystems? If research on sea floor ecosystems from 3400 to 16100 years ago indicate that local extinctions took place, couldn't research be done about the organisms living in sea floor ecosystems currently put in danger by global warming and climate change, in order to try to find a way to prevent local extinctions today?

By AG Woodley - u… (not verified) on 04 Apr 2015 #permalink

According to Carl Zimmer a research study has shown that the world's coral reefs has declined by 40 percent due to higher temperatures. This can lead to extinction of organisms that depend on coral reefs to live. The increase in CO2 causes the seawater to become more acidic. According to Dr. McCauley if we limit the industrialization of the oceans to some regions it can allow threatened species to recover in different regions.

By u15035752 (not verified) on 05 Apr 2015 #permalink

In all studies of global warming and it's effects on the organisms,has it helped to finding its share in causing the mass ancient mass extinctions?

By Dibetso polly … (not verified) on 05 Apr 2015 #permalink

The disruption of marine ecosystems due to climate change occurs rapidly. Scientists have stated that it could possibly take hundreds, if not thousands of years for organisms to recover. There seems to be a rapid loss in marine diversity due to low levels of oxygen present in the sea water. With that being said, we need to limit the tremendous changes in climate in order to reduce the destruction of ecosystems.

By DS Moosa (15027504) (not verified) on 06 Apr 2015 #permalink

@ DS Moosa , you are right we need to reduce the destruction our ecosystems endure. But HOW? At some point we have to stop asking how and take charge be innovative, know what is being done and as future leaders take charge. @ Keagan Loader it's not that we are looking at the effects on complex organisms now, we have recently realised that the marine population is endangered and we found out WHY so now complex organisms are treated with a sense of urgency because without them we are also going to become extinct. The truth is we've ruined our planets resources and now we find that we cannot make them ourselves and that the Earth requires thousands or millions of years to recover. Greed has changed the way things were, what good is it for a government to make fishing laws if they are violated? What good is it for certain companies to pay tax because of their carbon emissions while in other countries carbon tax is not encouraged? What we all need is to dream of a day when it's too late to save Earth from ourselves.

By TRK Ngaka u15103634 (not verified) on 06 Apr 2015 #permalink

Climate fluctuations cause evapotranspiration in the underwater plant life..
This decreases the sea-levels and the amount of oxygen in the water which in turn harms aquatic life. u14301815

By Arthur Grüner … (not verified) on 07 Apr 2015 #permalink

It's quite amazing how the rise of the average temperature of just a few degrees has such an enormous effect on our ecosystems. It just shows how fragile our plant is.

By M.R Revolta (u… (not verified) on 17 Apr 2015 #permalink