Study:
Dead sea creatures covered 98% of seafloor last year about 150 miles
off California coast
Unprecedented,
had been below 1% prior to event — ‘Major’ changes began in
spring 2011
11
December, 2013
National
Geographic,
Nov. 22, 2013: [...] “In the 24 years of this study, the past 2
years have been the biggest amounts of this detritus by far,”
said study leader Christine Huffard, a marine biologist at the
Monterey Bay Aquarium Research Institute in California. [...] In
March 2012, less than one percent of the seafloor beneath Station M
[located 145 miles west of the coast of California between Santa
Barbara and Monterey] was covered in dead sea salps. By July 1, more
than 98 percent of it was covered in the decomposing organisms,
according to the study, published this week in the Proceedings of the
National Academy of Sciences. [...] Although climate change is
a leading contender for explaining the major increases in 2011 and
2012, Huffard says that these spikes could be part of a longer-term
trend that scientists haven’t yet observed. She hopes to continue
gathering data from Station M to try and figure it out.
Proceedings
of the National Academy of Sciences,
Nov. 11, 2013 (emphasis
added):
[...] Two major peaks in POC [particulate organic carbon] flux
occurred over the last 18 mo of the time series [...] The peak POC
flux in spring/summer 2011 was the highest recorded over the 24-y
time series (Fig. 1D) [...] The daily presence of detrital
aggregates on the sea floor did not exceed 15% coverage over the
period from 1990 to 2007. The highest sea-floor coverage by detrital
aggregates measured throughout the 24-y time series occurred between
March and August 2012, when salp
detritus ranged from <1% cover in early March to a high of 98%
cover on 1 July (Fig.
1E). This was the only measurable deposition event of salps observed
during the entire time series. Following this salp pulse,
phytodetrital aggregates combined with some salp detritus formed
another major deposition event beginning in late August and peaking
in mid-September. This pulse covered up to 61% of the sea floor (Fig.
1E), the largest primarily phytodetrital aggregate peak recorded
during the time series. [...] Although environmental variation, such
as air temperature and winds, affect the physical dynamics of this
upwelling ecosystem, the specific mechanisms behind the changes in
food-supply composition and food-web processes corresponding with the
peaks in 2011 and 2012 remain unknown. Such increases in food supply
appear to change the structure and functioning of deep-sea
communities. We already are observing significant changes in
populations of benthic fauna [...]
Study’s
Supporting Information: Sea
Floor Megafaunal Community Change [...]
Over an 18-mo period beginning in spring 2011, the densities of
epibenthic animals increased by nearly an order-of-magnitude and
diversity was considerably lower. Major faunal changes included a
substantial reduction in sponge and other sessile animal abundance,
and by late 2012 three holothurian species were at the highest
densities recorded since mobile megafaunal investigations began in
1989.
No comments:
Post a Comment
Note: only a member of this blog may post a comment.