Taphonomy of barnacle and fish shoreline
accumulations of the Salton Sea, California, USA
Heness,
Elizabeth A., Wilk, Jewels, Kraal, Erin, Malenda, H.
Fitzgerald, and
Simpson,
Edward, 2011, Taphonomy of barnacle and fish shoreline
accumulations of the Salton Sea, California, USA [abs]: Geological
Society of America - Annual Meeting in Minneapolis, Minnesota
(9–12 October 2011), Vol. 43, No. 5, p. 425.
From 1905-067, the Salton sink was flooded by Colorado River water.
Since the flooding event, the closed lake system level has been
maintained largely by agricultural runoff and river inflow. The
closed basin experiences high evaporation rates causing an increase
in salinity and eutrophic conditions which prompt an evolving
ecosystem. However, massive die-offs have removed all fish except
the hybrid tilapia (Oreochromis
mossambicus x O. uroepis)
and the barnacle (Balanus
amphirite). As a result, tilapia and barnacles dominate the
Salton Sea shoreline sediments.
During high wind events, overturning of the stratified water column
generates algal blooms reducing dissolved oxygen and stirring up
phosphates and sulfides causing high mortality events in the tilapia
population and break barnacles off their substrates. This study
reports on the application of a semi-quantitative fish articulation
scale that describes the fish kill and barnacle preservation across
the shoreline.
We developed a semi-quantitative scale that varies from 1 to 5; each
integer reflects an increase from whole to total fish
disarticulation. Barnacles were described as clustered (two or more
attached to one another), whole, or crushed. An overall trend from
articulation to disarticulation occurs from the shoreline to the
backshore. The storm high-water line reflects the maximum
articulation and predation of fish and the occurrence of clustered
barnacles. In the swash zone barnacles are reduced from clusters to
whole to crushed. On high lake-level beach ridges, barnacles and
fish parts form low-angle, lake-ward dipping foresets. Rare landward
dipping forests are present and record storm wash over. Storm
washover fans are well developed along some portion of the shoreline
and dominated by clastics, crushed barnacles, and abundant skeletal
tilapia parts. This assessment permits us to study a rare
biological, rather than clastic, dominated lacustrine shoreline and
can be applied to preserved deposits in the rock record.
Taphonomy of barnacle and fish shoreline
accumulations of the Salton Sea, California, USA 