2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
Recommendations
No changes to the fisheries monitoring program are recommended at this time. The next monitoring is
scheduled to occur in Year 5, with sampling events in October 2010, and January, April, and July
2011.
1.4. BENTHIC MONITORING
Introduction
The Monitoring Plan calls for benthic invertebrate monitoring to be initiated in Year 2 (October 2007
to September 2008) and to be repeated in Years 5 and 10 following the opening of the FTB to the
ocean. The Year 2 sampling was conducted in January and July of 2008. The objective of the benthic
monitoring task in the Monitoring Plan is to characterize the marine invertebrate food resources
available to birds and fish, as well as provide an index of general habitat quality in the basin.
Methodology
Infauna
Three benthic sampling stations were established in the FTB: one along the north eastern shore, one
along the western shore, and one in the southern portion of the basin (Figure 1-11). Three replicate
collection points were established for each station. At each replicate point, a sediment core was
collected from the + 0.3-m (+1-foot) NAVD elevation and from the -0.6-m (–2-foot) NAVD elevation.
These elevations will be referred to in feet throughout this section. The elevations were estimated
based on the water level compared to a known elevation at the east Water Control Structure in January
2008. During the second sampling in July 2008, the tidal range in the basin had been altered due to
tidal muting caused by the accumulated flood shoal in the basin inlet, and the point of core collection
had to be adjusted accordingly to best approximate the true tidal elevation.
The sediment cores were collected using a 15-cm diameter corer inserted
to a sediment depth of 15 cm, and rinsed through a 1.0-mm sieve. The
sediment area sampled by each core was 0.018 m 2 . Core collection
unavoidably captured the biota occurring on the surface of the sampled
core, as well as in the water column for the –2-foot NAVD samples.
Therefore, the collected samples could include epibenthic and open water
organisms along with the infauna. Although captured fish were removed
from the samples, all other organisms were retained and worked up along
Sieving a sediment core.
with the infauna. Organisms from each sample were placed in
containers, preserved in a buffered 10% formalin:seawater solution, and transported to the laboratory
for subsequent analysis.
After approximately one week, organisms collected from the benthic cores were transferred in the
laboratory into 70% isopropyl alcohol. All individuals in each replicate sample were identified to the
lowest practical taxonomic level, counted, and the wet weight measured. Wet weight was determined
by transferring the sample, including alcohol, onto a paper towel and blotting quickly to remove excess
liquid from the animals. Organisms were then transferred to a tared weighing dish and weighed to the
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