Abstract
Videotape footage taken on remotely operated vehicle (ROV) dives from
03/09/89 to 05/14/91 was used to examine the distribution and behavior of the upper
mesopelagic shrimp Sergestes similis in Monterey Bay. A quantitative method of
determining relative density was developed and used to show that the abundance of
S. similis is significantly higher at a site in the vicinity of the Monterey Canyon wall as
compared to one mile from the wall. Vertical distribution of the dielly migrating
shrimp also appears to shift upward with the slope of the canyon. Studies with
horizontal transects showed densities at 100 m from the wall not to significantly differ
from those in the water column. However, density increased significantly within 50 m
of the wall to a highest relative value at the water column/slope interface. Behaviora
studies showed S. similis to play a role in the trophic structure of the slope benthic
community. Overall, canyon topography was determined to have important
influence on S. similis distribution and behavior.
Introduction
Sergestes similis Hansen 1903 is a major component of the upper mesopelagic
community of the North Pacific, ranging from Japan through the Bering Sea to the
Gulf of California (Krygier & Wasmer, 1988; Milne, 1968). Found off California in
Monterey Bay first in 1921 (Schmitt, 1921), it is one of the main species correlated
with the deep scattering layers in Monterey Bay (Barham, 1957). Sergestes similis has
an average length of 40 mm and is readily identified by its long antennae and red
abdomen (Omori, 1974). It matures in its first or second year and has a life span of
1-3 years (Nybakken, 1988; Omori, 1974). It spawns in Monterey Bay generally in
December-January and June-July (Vernberg, 1983; Omori, 1974).
Sergestes similis is classified as a strong vertical migrator (Pearcy et al., 1977),
ascending to within 50 m of the surface at night and descending to approximately 500
m by day (Judkins, 1972; Omori & Gluck, 1979). Rarely does it descend below 1000
m (Krygier & Pearcy, 1981). Although described as a "truly holoplanktonic" decapod
by Raymont (1983), S. similis may interact with the benthos due to the topography of
the Monterey Submarine Canyon. Öften, contact between midwater migrants and
the seafloor occurs on steep slopes where the depth is shallower than the usual range
of diel migration (Isaacs & Schwartzlose, 1965; Ömori & Ohta, 1981). Raymont
(1983) reports for S. similis that biomass is large in regions of upwelling with a steeply
sloping bottom, two characteristics of Monterey Bay.
A major problem in assessing micronekton distribution is patchiness, the
aggregation of individuals that may be caused by physical or ecological processes or
by behavioral phenomena (Hamner, 1988; Omori, 1983; Haury et al., 1978).
Patchiness on the fine-scale (meters to hundreds of meters), the ability of sergestids
to avoid nets, and the inability of nets to sample near-bottom all act to obscure
results of past studies on S. similis distribution (Robison, 1982; Omori, 1974). To
better examine the population of S. similis in the Monterey Canyon and its
interactions with the slope benthos, a visual study was conducted with a remotely
operated vehicle (ROV) owned by the Monterey Bay Aquarium Research Institute
(MBARI). Using a quantitative method developed to calculate relative densities, the
S. similis population near the canyon wall was compared to a site a mile more toward
the center of the canyon. The ROV also allowed for an in situ behavioral study of S.
similis. Benthic interactions as well as other behavioral characteristics of S. similis
were observed to note any influence of canyon topography on behavior.
Materials and Methods
Sergestes similis were recorded on betacam videotape footage taken by a DXC
3000 Sony Camera mounted on the ROV during dives from 03/09/89 to 05/14/91. All
tapes are annotated in a database for sightings of various organisms, including
sergestids. Each video frame is time-coded and correlated to hydrographic and
navigational data from the RÖV, including depth, salinity, temperature, and 09
Sergestes similis was observed at six dive sites in Monterey Bay (Figure 1).
Distribution
The two sites used to study S. similis vertical distribution were the C4-CS site,
located in the vicinity of the canyon wall with bottom depth approximately 500 m,
and the H9O Column site, approximately one mile from the wall site toward the
center of the canyon with bottom depth approximately 1000 m. Out of 80 dives, 38
were chosen to examine vertical distribution. Only those dives correlated with
hydrographic data and descending at similar times were examined. (As shown in
Figure 2, the fact that S. similis vertically migrates had to be taken into account.)
Using the videotapes and database, the number of S. similis sighted and the amount
of time spent by the ROV in transit with a wide angle camera setting was determined
for each specified depth increment for 15 C4-CS and 23 H9O Column dive descents.
Two night dives at the H9O Column site were also reviewed. Depth increments were
0-25, 25-100, 100-200, 200-250, 250-300, 300-350, 350-400, 400-450, 450-500, and 500
550 m. (At depths above 25 m, most of the time is spent launching or recovering the
ROV; thus the 25-100 m increment gives a more accurate picture of the upper 100
m.) Also noted for each dive descent were the greatest depth reached by the ROV
and the shallowest and greatest depth at which a sergestid was sighted. The ROV
did not exceed a depth of 520 m. Plots of relative abundance by depth as determined
by number of sergestids per videoscreen were prepared for each dive.
Relative density was calculated for each depth increment for each dive by
dividing the number of S. similis sighted by the number of minutes in transit. Density
in 4 sergestids/min (Sergs/min) was calculated for each dive overall and for each site
at each depth increment. The calculation procedure assumes that when the ROV is
moving with camera set for a wide angle view, the volume observed is sufficiently
similar at different times to compare densities using frequency of occurrence. The
method also assumes the sample size of observations is large enough to compensate
for differences in the speed of the ROV at different times. Relative density for each
dive and each site was also expressed as a ratio of the number of sergestids sighted to
the range of the depths at which sergestids were sighted (called "vertical patchiness
density") and as a ratio of the number of sergestids sighted to the greatest depth
reached by the RÖV. Each of these ratios have units in Sergs/m.
Relative density of S. similis near the canyon wall and at the H2O Column site
was also compared by conducting horizontal transects for varying lengths of time at
depths between 300-500 m on 11 dives. Seven transects paralleling the canyon wall
at 100 m from the wall (determined by sonar) and 17 transects at the H2O Column
site were completed. The depth, time, number of sergestids sighted, and time spent
in transit were noted for each transect, and density was calculated in Sergs/min.
Horizontal transects were also conducted perpendicular to the canyon wall to
examine changes in sergestid density within 100 m of the wall. Distance to the wall
was split into ten 10 m increments. Distance to the wall was read off sonar and
recorded on the audiotrack for the videotape. The number of S. similis sighted and
the time spent moving in each distance increment was noted and used to calculate
relative density as above.
Behavior
All database citations of sergestids from approximately 100 dives were
reviewed to examine behavioral patterns. Sergestes similis was observed for benthic
interactions such as touching, darting away from, or being captured by benthic
organisms and for apparent scavenging in the benthic detritus. Sergestids were also
observed when the RÖV held an approximately 25 cm screen-width view of the
bottom. Instances of apparent schooling and swarming were also recorded and
noted for proximity to the slope bottom. The speed of S. similis was calculated
several times by taking the ratio of the change in RÖV depth to the change in tape
time code as the ROV followed an organism’s descent.
Statistical Tests
Statistical tests for differences between mean densities for most of the
distributional data sets included standard parametric two-tailed t tests and
nonparametric Mann-Whitney U tests. The two-sample t test assumes that both
samples come at random from normal populations with equal variances. Although
the two-tailed t test is robust enough to withstand considerable departure from
assumptions, the Mann-Whitney test may be much more powerful for those data sets
with smaller sample sizes (Zar, 1984).
Results
Distribution
38 ROV descents at the C4-CS and H9O Column sites from 04/26/89 to
05/07/91 were reviewed. The number of Sergestes similis and the number of minutes
spent in transit for each depth increment for each dive and for the dive overall are
presented in Appendix 1 along with the calculated density in Sergs/min. Figures 4 &
5 show the S. similis vertical distribution as determined by number per video screen
for the C4-CS and H9O Column sites, respectively. The dives are plotted separately
by month, but no seasonal changes in distribution are readily apparent. Sergestids
were sighted above 200 m depth on only one C4-CS dive - 05/06/91 and three H2O
Column Dives - 06/15/89, 07/16/90, and 07/23/90. Only one dive at each site extended
below 500 m.
Overall densities for each depth increment for each site are presented in Table
1 and graphed in Figure 6. Overall density in Sergs/min was calculated for each
depth increment at each site in two ways: as a ratio of the total + sergestids sighted
total + min for all dives and as the mean of the depth increment densities calculated
for each individual dive. The mean density value is used in statistical comparisons.
The three highest depth increment densities, » 30 Sergs/min, occurred at the C4-Cs
site in the 250-300, 300-350, and 350-400 m increments. The overall densities of
these three depth increments also proved to be significantly higher at the C4-C5 site
at the .01 level (Table 13). No significant difference in density between the two sites
was observed for the other depth increments. Differences in mean density values
between depth increments at each individual site were not significant except for
between the 200-250 and 250-300 m increments at C4-CS, significant at the .05 level.
As shown in Figure 6, the overall densities for each depth increment at each
site appear to follow a bell-shaped curve with maximum for the C4-CS site in the 300.
350 m increment, at 9.333 Sergs/min, and maximum for the H2O Column site in the
350-400 m increment, at 0.983 Sergs/min. Taking all 38 dives collectively, the highest
density, 3.453 Sergs/min, occurs in the 350-400 m increment. Over all depths, the
mean density at C4-CS was 4.323 Sergs/min in comparison to 0.736 at the H»O
Column site (Figure 9). A frequency distribution of overall dive densities (Figure 7)
shows the H9O Column site dives have a much greater probability of having a low
number of sergestid sightings per descent.
Density in terms of + S. similis sighted per depth range of sightings was also
significantly greater at the C4-CS site (1.008 vs. 0.237 Sergs/m) at the .01 level. This
"vertical patchiness" density is reported for each dive in Table 2 and graphed in
Figure 8. The average depth range of sergestid sightings was similar at the two sites,
but the average number of sergestids sighted per dive was 145.53 at C4-CS vs. 25.13
at H9O Column, an order of magnitude difference (Appendix 2). The greatest
"vertical patchiness" density value, 5.116 Sergs/m, came from the 12/20/89 dive at C4-
C in which 566 sergestids were sighted over 110 m. Not surprisingly, this dive alse
had the highest overall density in terms of Sergs/min, 14.15, and the highest value for
+ Sergs/greatest depth of dive, 1.433 (Table 2). Density given by the average
number of sergestids sighted / the average greatest dive depth at each site was also
six times higher at C4-CS: 0.353 vs 0.059 Sergs/m (Appendix 2). Overall values for
densities calculated in all three ways are shown for each site in Figure 9.
Vertical distribution of S. similis at night was at much shallower depths
(Figure 11). Five of twelve sightings of single organisms were in the upper 100 m
(Figure 14). One sergestid was sighted at 286 m. In Sergs/min, the density at the
H9O Column site at night was an order of magnitude lower than during the day
(Table 7, Figure 12). No statistical tests were conducted because only two night dives
were made.
Abundance of S. similis at 100 m from the canyon wall was compared to that
at the H9O Column site using horizontal transect results. Table 3 lists data for each
individual transect, and Table 4 shows the results for the transects overall and split
into two depth increments, 300-400 and 400-500 m. The average density results for
transects at the H9O Column site were first compared to those observed in the 300
500 m range during H90 Column dive descents and were found statistically to be the
same (Table 14). Although Figure 13 shows the density for H2Ö Column transects
higher than for those paralleling the wall in each depth increment and overall, no
significant difference was observed between the mean densities (nor between mean
densities of the two depth increments at each individual site). Densities at the H20
Column site had the greatest range (0-11.321 Sergs/min) and eight of seventeen H2C
Column transects had no sergestid sightings (in comparison to two of seven transects
100 m from the wall).
Data for each of the 26 horizontal transects conducted perpendicular to the
wall are shown in Appendix 3. Twenty-five transects reached to 50 m and 7 reached
to 100 m from the wall. It appears qualitatively that the density of S. similis is
greatest at the canyon wall, reaches its lowest value at 50 m from the wall, and then
increases again to a second peak in the 70-80 m increment (Table 5, Figure 10).
Values for distances greater than 60 m are not, however, statistically manageable due
to sample size. Mean densities of distance increments up to 60 m from the wall were
compared, and a significant difference was found between the following distance
increments: 0-10 and 30-40 m, 0-10 and 40-50 m, and 20-30 and 40-50 m (Tables 13
& 14). Density values for the 90-100 m distance increment were combined with
those from transects paralleling the wall and found not to be statistically different
from density values at H90 Column site dives in the 300-500 m depth range (Table
14). The transects perpendicular to the wall were also split into two depth
increments of 340-420 and 420-510 m (Table 6). Although the densities are always
higher at the shallower depth increment (Figure 10), no significant differences in
densities between depth increments were observed.
Behavior
Ten dives from 03/28/89 to 09/24/90 at 4 sites had video footage of S. similis
interacting with benthic organisms (Appendix 4). Organisms touched varied from
crabs to holothurians to starfish. The greatest number of observed interactions were
with starfish, yet many of these close-up observations may be biased by attraction to
ROV lights. The number of sergestids to dart away from an organism touched was
noted, and 97 of 110 occurrences of touching a benthic organism were followed by
the darting "reflex" (Table 8). A starfish, sea anemone, and benthic fish were
observed capturing a total of five sergestids (Table 8). Five instances of sergestids
that appeared to be foraging among the benthic detritus were observed from two
dives at the North Wall and C4-C5 sites. In each case, the sergestid was calm, not
darting away from the benthos (Table 9). Observations of S. similis made with a
screen viewing width of approximately 25 cm were made on 4 dives. With this screen
width, many were observed simply skimming over the bottom, and 43 of 46 sergestids
to actually touch the bottom darted off (Appendix 5).
Out of the 100 dives analyzed, only six instances of sergestid schooling
behavior from 5 dives were noted (Table 10), and only three instances of what may
be considered swarms of S. similis were observed (Table 11). The largest "school"
consisted of four individuals swimming horizontally, and the highest density observed
for a "swarm" was greater than 100 sergestids per videoscreen with a wide angle
camera setting. All but one instance of schooling and swarming were within sight of
the benthos.
Descent speeds calculated for S. similis ranged from 0.04 to 0.105 m/s, with an
average of 0.075 m/s (Table 12). These speeds were measured at the H2O Column
site at various depths between 320 and 425 m. Although S. similis generally appeared
to have a random orientation both near the bottom and in the water column,
sergestids in the water column were often observed descending vertically.
Discussion
In situ observations are difficult to interpret for crustaceans because they are
photosensitive and capable of rapid escape from or of being attracted to a
submersible (Mackie, 1985). In assessing the results of the distributional and
behavioral studies, such biases as the light, noise, and leading "bow wave" of the
ROV must be kept in mind (Bowers, 1988). In distributional studies, bias was
reduced by counting sergestids only while in transit at a speed fast enough to keep
them from being attracted to the RÖV. In ethological studies, bias was reduced by
excluding observations of behavior when the sergestids were obviously disoriented by
or attracted to the RÖV light.
Distribution
Previous studies of Sergestes similis depth distribution off Oregon and
southern California place the species at approximately 250-600 m during the day and
0-200 m at night (Omori & Gluck, 1979; Judkins & Fleminger, 1972). Krygier &
Pearcy (1981) found S. similis most abundant off Oregon in 200-300 m, followed by
300-400 m. Overall depth increment densities for the dives in this study place the
highest abundance of sergestids in the 300-400 m range in Monterey Bay. At night
off Oregon, Pearcy & Forss (1966) had the highest catches of S. similis in the uppei
50 m, with some below 150 m (1969). Because only two night dives were made by the
ROV, no general trends can be inferred, although the greatest number of individuals
was seen at about 100 m depth, correlating with others research.
Although there may be some regional differences in the vertical distribution
of a single species due to such factors as temperature or light penetration (Flock,
1989), it appears the observations made with the ROV put the S. similis population
of Monterey Bay in generally the same range as off Oregon and southern California.
The entire depth distribution can not be adequately characterized, however, because
the ROV was unable to reach depths greater than 520 m. As shown in Figures 4 & 5,
dives often ended in the midst of the sergestid population. And although Barham
noted an upward change in depth of the Monterey Bay scattering layer with seasonal
upwelling, no seasonal changes in depth distribution are obvious from the dives
studied.
Although not statistically significant (possibly due to small sample size), the
apparent difference in vertical distribution at the C4-CS and H9O Column sites
indicates a "meniscus effect" likely influenced by canyon topography. In examining
Figure 6, it appears the population at the C4-CS site is shifted up about 50 m; the
highest density for the C4-CS site was in the 300-350 m increment, while at the H2O
Column site, highest density was at 350-400 m (Table 1). An upward population shift
at the wall site could be due to sergestids caught in shallower water during their daily
migration. Tsukai (1985) observed a related species, Sergia lucens, at 250 m near
bottom on the slope of Sagami Bay and at 300-350 m in midwater. Raymont (1983)
notes that upwelling and a steep slope may bring organisms closer to the surface, and
Marshall & Merrett (1977) report the depth distribution of mesopelagic organisms
may well be modified by proximity of the bottom over a continental slope.
In terms of general vertical patchiness, it appears qualitatively that S. similis is
more dispersed at the H90 Column site (compare Figures 4 & 5). One would expect
that vertically migrating organisms caught over a shallower slope such as the C4-C5
site would assume a more compact, concentrated, less extensive vertical range of
depth distribution. Dive results do not show the average depth range of S. similis
sightings to differ between the two sites, likely because the RÖV did not extend
through the full vertical range of sergestid distribution. However, the higher value
for "vertical patchiness" density at the C4-CS site does support the above expectation.
Having a greater number of S. similis sighted over similar depth ranges of sightings
shows the population is more concentrated at the wall site and more dispersed
vertically at the H9O Column site.
Barham suggests that micronektonic midwater organisms randomly distribute
within a given horizontal substratum (1957), yet it appears this substratum is
vertically quite extensive because no significant differences in density were found
between depth increments at the H9O Column site. Although qualitatively it did
appear that the density of sergestids increased as the RÖV approached bottom, data
obtained in this study also showed no significant difference in density between
successive depth increments at the C4-CS site (except between the shallower 200-250
and 250-300 m increments) (Table 13). Ömori and Ohta (1981) simply assume in
areas such as submarine canyons that the density of migrating micronekton is much
higher near bottom in the day than in the overlying midwater. RÖV dives would
have to descend vertically directly over a certain spot on the canyon slope to better
illustrate Omori and Ohta’s assumption for the C4-C5 site.
In overall analysis, distribution by site indicates a greater abundance of S.
similis near the canyon wall as opposed to one mile from the wall. This difference in
overall average density, 4.323 as compared to 0.736 Sergs/min, is likely a result of the
bottom topography's influence on distribution. Similarity in temperature and salinity
curves at the two sites suggests hydrographic factors are not causing the difference
(Figure 3). The fact that the average density calculated for transects paralleling the
wall at 100 m from the wall was not statistically different than that for transects at the
H9O Column site appears to suggest that S. similis distribution at 100 m from the
wall is not significantly affected by the proximity of the wall. This surprising
observation is possibly the result of having a small sample size of transects for such a
patchily distributed organism. But the observation of similar densities is also
supported by the fact that all densities calculated at 90-100 m from the wall in
comparison to the densities calculated for H2O Column dives at 300-500 m are
statistically the same. This suggests that interaction with the wall takes place on an
even finer scale than 100 m.
This scale was examined with transects made perpendicular to the wall.
Although results from the perpendicular transects cannot be taken with high
confidence (due to small sample size and high variance), the quantitative results do
appear to correlate with the qualitative observations of greater density within a few
tens of meters from the wall (Figure 10). The distance increment of 0-10 m from the
wall had significantly higher density than that found for the increments 30-40 and 40-
50 m, suggesting a high degree of direct interaction takes place between S. similis and
the canyon wall. Density was found to change significantly within distance
increments of only 20 m. It would be interesting to compare this scale of horizontal
patchiness with that observed in the H2O Column transects; however, the ROV is
not yet equipped with a flowmeter to estimate distance travelled.
Behavior
The benthopelagic region, defined as the bottom 100 m of the water column
(Wishner, 1980), is noted for its greater biomass, species diversity, and variability of
niches in comparison to the pelagic zone (Larson et al, 1991). The proximity of S.
similis to the canyon slope and wall allows it to be characterized as a "facultative
benthopelagic" organism in Monterey Bay. The three cases of highest observed
density were noted at the wall just off bottom (Table 11). Ömori and Ohta (1981)
found the highest density of the related species S. lucens also within 10 m of the
bottom during the day. Although Omori and Ohta (1981) did not note S. lucens less
than 0.5 m from the bottom, S. similis was often seen directly interacting with the
bottom and benthic organisms. Close-up observations with the RÖV documented
instances of a high number of sergestids skimming over the bottom. Although
observations made with a 25 cm screen width might suggest persistance of micro-
scale patches, it is likely that these aggregations were the result of an attraction to the
ROV's light (Appendix 5). Sergestids were also seen darting away in response to
touching many different classes of benthic organisms (Appendix 4, Table 8). The
darting "reflex", a rapid flexure of the abdomen, is a behavior first characterized by
Barham (1957) in the laboratory. Those sergestids appearing to forage among the
detritus did not exhibit this behavior.
Instances of apparent foraging as well as being captured at the benthos
suggest that S. similis plays a larger role than previously thought in the trophic
structure of the benthopelagic community. Many researchers state that S. similis is
preyed upon by rockfish, albacore, and squid off Oregon, but no mention is found of
S. similis in the diet of sea anemones and starfish (Ömori, 1974; Donaldson, 1975).
Interestingly, S. similis was found to be a large part of the diet of Apolemia uvaria, a
siphonophore found more frequently near the Monterey Canyon wall (Soohoo,
1990). Many researchers also note that over steep rises, typical members of the
midwater community may approach the bottom and become the food of
benthopelagic fishes; Pereyra (1969) notes rockfish may live in a particular area of a
canvon because diel vertical migrators caught in currents concentrate there
(Marshall & Merritt, 1977; Isaacs & Schwartzlose, 1975). Interestingly, Raymont
(1983) also states that decapods appear concentrated in strata close to rich layers of
food. In Hamner’s discussion of patchiness (1988), he defines a coincidental group
as one formed by attraction to a resource. It is possible that the S. similis patches just
off the wall may be aggregations responding to the richer food source at the wall vs.
in the more dispersed pelagic realm.
The apparent scavenging behavior of S. similis shows the benthos as a possible
source of food during the day. It is often thought that vertical migrators ascend at
night to feed; thus the majority of S. similis feeding would be expected at night
(Walters, 1976). Although most researchers report more intense feeding by night
(Renfro and Pearcy, 1966; Judkins, 1972), other Sergestes species feed well into the
day (Flock, 1989). And although often characterized as a carnivore feeding on
copepods and euphausiids (Judkins, 1972; Renfro & Pearcy, 1966), other researchers
have suggested that S. similis also plays a role as a midwater scavenger (Foxton &
Roe, 1974; Flock, 1989; Barham, 1957; Omori, 1974; Nishida, 1988). Observations of
this study suggest that sergestids may play a role as benthic scavengers also.
Observations also showed S. similis to have the propensity for forming schools
and swarms near bottom, although these were not general behaviors. Schooling,
defined as swimming with regular interindividual spacing and directional orientation
(Omori and Hamner, 1982), was noted for about three individuals at a time (Table
10), yet even when three individuals were "schooling," all other organisms in the
vicinity were oriented randomly. And although other researchers have noted S.
similis in dense swarms exceeding 20 individuals/ m2(Omori, 1974; Raymont, 1983),
no true swarms (as often observed for euphausiids) were observed for S. similis on
the over 100 dives examined.
A last interesting characteristic of S. similis to note is its descent speed. The
speed calculated from the ROV videotapes, 0.075 m/s, is strikingly similar to that
determined by Barham in the laboratory, 0.08 m/s (1957).
Summary
In the final analysis, it appears that the topography of the Monterey Canyon
plays an important role in influencing the distribution and behavior of S. similis on
both the meso and fine scale. The resources of MBARI and the video capabilities of
the ROV have illustrated a better picture of S. similis ecology in Monterey Bay.
Several interesting questions remain. Is there an active preference of the
canyon wall habitat by an S. similis population? Are the sergestids aggregating near
bottom for the food source or are they there as a result of currents running up
through the canyon interacting with vertical migration ranges? Is the actual
percentage of organisms that vertically migrate on a given night greater at the H20
Column site due to lack of benthopelagic feeding during the day? Are S. similis age
classes segregated in their distribution? Future research with the ROV may provide
answers.
Acknowledgments
I would like to give special thanks to the crew of the Pt. Lobos who pilot and
launch the ROV. Thanks are also given to Lynn Lewis, Annette Gough, Debbie
Littlefield, Pat Tompkins, Marilyn Yuen, Hans Jannasch, and Dan Davis at MBARI
for helping me use the video equipment, understand the database, and learn various
computer techniques. Thanks are also given to Lisa Cooke for helping me narrow
down my procedure, to Emily Bell and Doug Stoner at Hopkins Marine Station for
helping me comprehend IBM statistics software, and to Alan Baldridge and the
Hopkins library staff.
Extra special thanks are given to Dr. Bruce Robison and Dr. Charles Baxter.
Robie and Chuck gave me the chance of a lifetime - to do science in the deep sea. I
appreciate all their help and advice and look forward to working with RÖVs in the
future.
Literature Cited
Barham, Eric G. 1957. The ecology of the sonic scattering layers in the Monterey Bay
area. Hopkins Marine Station Technical Report 1. Stanford University.
Bowers, James. 1988. Diurnal vertical migration of the opossum shrimp Mysis relicta in
Lake Superior: Observations and sampling from the Johnson-Sea-Link II Submersible.
Bulletin of Marine Science 43(3): 730-738.
Donaldson, H.A. 1975. Vertical distribution and feeding of sergestid shrimps
(Decapoda: Natantia) collected near Bermuda. Marine Biology 31: 37-50.
Flock, Mark E. 1989. The vertical distribution and feeding ecology of sergestid shrimp
(Decapoda; Natantia) in the eastern Gulf of Mexico. Master's Thesis. University of
South Florida.
Foxton, P. & H. Roe. 1974. Observations on the nocturnal feeding of some mesopelagic
decapod Crustacea. Marine Biology 28: 37-49.
Hamner, William M. 1988. Behavior of plankton and patch formation in pelagic
ecosystems. Bulletin of Marine Science 43(3): 752-757.
Haury, H.R., J.A. McGowan, & P.H. Wiebe. 1978. Patterns and processes in the time-
space scales of plankton distributions. In: John H. Steele (ed.), Spatial Pattern in
Plankton Communities. Plenum: New York, NY.
Isaacs, John & Richard Schwartzlose. 1965. Migrant sound scatterers: Interaction with
the seafloor. Science 150: 1810-1813.
Judkins, David & Abraham Fleminger. 1972. Comparison of foregut contents of
Sergestes similis obtained from net collections and albacore stomachs. Fishery Bulletin,
U.S. 70(1): 217-223.
Krygier, Earl & William Pearcy. 1981. Vertical distribution and biology of the pelagic
decapod crustaceans off Oregon. Journal of Crustacean Biology 1(1): 70-95.
Krygier, Earl & Robert Wasmer. 1988. Zoogeography of pelagic shrimps (Natantia:
Penaeidea and Caridea) in the North Pacific Ocean (with synopses and keys to the
species of the Subarctic and Transitional Zones). Tokyo University Ocean Research
Institute Bulletin 26(1): 43-98.
Larson, R.J., G.I. Matsumoto, L.P. Madin, & L.M. Lewis. 1991. Deep-sea benthic and
benthopelagic medusae: recent observations using submersibles and a remotely operated
vehicle. Unpublished.
Mackie, G.O. 1985. Midwater macroplankton of British Columbia studied by the
submersible Pisces IV. Journal of Plankton Research 7(6): 753-777.
Marshall, N.B. & N.R. Merrett. 1977. The existence of a benthopelagic fauna in the
deep-sea. In: Martin Angel (ed.), A Voyage of Discovery. Pergamon: Oxford, U.K.
Milne, Darrelyn. 1968. Sergestes similis Hansen and Sergestes consobrinus n. sp.
(Decapoda) from the NE Pacific. Crustaceana 14: 21-34.
Nishida, Shuhei, et al. 1988. Feeding habits of mesopelagic shrimps collected off
Oregon. Tokyo University Ocean Research Institute Bulletin 26(1): 99-108.
Nybakken, James W. 1988. Marine ecology: An ecological approach, second edition.
Harper and Row: New York. 445 pp.
Omori, Makoto. 1974. The biology of pelagic shrimps in the ocean. Advances in
Marine Biology 12: 233-324.
Omori, Makoto. 1983. Abundance assessment of micronektonic sergestid shrimp in the
ocean. Biological Oceanography 2(2): 199-210.
Omori, M. & David Gluck. 1979. Life history and vertical migration of the pelagic
shrimp Sergestes similis off the California coast. Fishery Bulletin of the U.S. National
Marine Fisheries 77: 183-198.
Omori, M. & W. Hamner. 1982. Patchy distribution of zooplankton: Behavior,
population assessment and sampling problems. Marine Biology 72: 193-200.
Omori, Makoto & Suguru Ohta. 1981. The use of underwater camera in studies of the
vertical distribution and swimming behavior of a sergestid shrimp, Sergia lucens.
Journal of Plankton Research 3(1): 107-121.
Pearcy, W.G., et al. 1977. Vertical distribution and migration of oceanic micronekton
off Oregon. Deep-Sea Research 24: 223-245.
Pearcy, William, & Carl Forss. 1966. Depth distribution of oceanic shrimps (Decapoda,
Natantia) off Oregon. Journal of the Fisheries Research Board of Canada 23(8): 1135-
1143.
Pearcy, William & Carl Forss. 1969. The oceanic shrimp Sergestes similis off the
Oregon coast. Limnology and Oceanography 14: 755-763.
Pereyra, Walter, et al. 1969. Sebastodes flavidus, a shelf rockfish feeding on
mesopelagic fauna, with consideration of the ecological implications. Journal of the
Fisheries Research Board of Canada 26(8): 2211-2223.
Raymont, John. 1983. Plankton and productivity in the oceans, second edition.
Pergamon: Oxford, U.K.
Renfro, W.C. & W.G. Pearcy. 1966. Food and feeding apparatus of two pelagic
shrimps. Journal of the Fisheries Research Board of Canada 23: 1971-1975.
Robison, Bruce H. 1982. Midwater biological research with the WASP ADS. Marine
Technology Society Journal 17(3): 21-27.
Schmitt, Waldo. 1921. The marine decapod Crustacea of California. University of
California Publications in Zoology 23: 1-470.
Soohoo, Nelson. 1990. Distribution and gut content analysis of the siphonopohore
Apolemia uvaria in the Monterey Bay Canyon. Hopkins Marine Station, Stanford
University. Unpublished.
Tsukai, F. 1985. Deep-sea fishes and other organisms in Suruga Bay - especially, on a
sergestid shrimp, Sergia lucens. Technical Resports of the Japanese Marine Science
Technology Center: 59-64.
Vernberg, John & Winona Vernberg. 1983. The biology of Crustacea. Vol. 8:
Environmental adaptations. Academic: New York.
Walters, John. 1976. Ecology of Hawaiian sergestid shrimps (Penaeidea: Sergestidae).
Fishery Bulletin, U.S. 74(4): 799-836.
Wishner, K.F. 1980. The biomass of the deep-sea benthopelagic plankton. Deep-sea
Research 27A: 203-216.
Zar, Jerrold. 1984. Biostatistical analysis, second edition. Prentice-Hall: Englewood
Cliffs, NJ. 715 pp.
Figure Legends
Figure 1.
Map of the Monterey Bay Canyon Illustrating ROV Dive Sites. Six sites were used for
observations of S. similis.
Figure 2.
Depth vs. Time Plot of First Sergestid Sightings for All Dives 03/20/89-02/28/91.
The plot was made to see if ROV observations tended to correspond to diel vertical
migration of S. similis. The plot also shows a linear regression and correlation
coefficient for the data.
Figure 3.
Salinity vs. Depth Plot and Temperature vs. Depth Plot for CA-C and H9O Column
Sites on Consecutive Days. The plots were made from the ROV's CTD data on
05/06/91 (C4-C5 Site) and 05/07/91 (H90 Column Site).
Figure 4.
Sergestes similis Depth Distribution as Determined by Sightings During ROV Descent:
C4-CS Site. The plot shows the presence and relative abundance of S.
similis as determined by number per screen for 15 dives 06/27/89-05/06/91. Greatest
depth reached by the ROV is also indicated.
Figure 5.
Sergestes similis Depth Distribution as Determined by Sightings During ROV Descent:
HoO Column Site. A plot (compare to Figure 4) for 23 dives 04/26/89- 05/07/91.
Figure 6.
Bar Graph of Depth Increment Density Totals for H90 Column vs. CA-C5 Site. Density
is expressed as the number of S. similis sighted per number of minutes of transit time.
Colored bars show total t of sergestids observed/ total f min spent in that increment
for all dives. X, the mean of the densities calculated for each depth increment for
each dive is given by the extended bar.
Figure 7.
Frequency Distribution of Overall Density for C4-CS vs. H9O Column Dives. Overall
density for each dive is calculated as the total it sergestids sighted / total f min of
descent time. Greatest depth reached for each dive is not taken into account for this
histogram.
Figure 8.
Vertical Patchiness as Determined by Number of S. similis Sighted Per Depth Range of
Sightings. To obtain a value for "depth range of sightings," the shallowest depth was
subtracted from the greatest depth at which a sergestid was sighted. The graph shows
the density in f sergestids / m for 38 dives and shows the mean of patchiness density
values calculated for each site.
Figure 9.
Comparison of Total Densities at H90 Column vs. C4-C Site. This graph shows:
overall density in sergestids/min for dives at each site over all depths, the mean f of
sergestids/ the mean greatest depth reached by the ROV per dive at each site, and the
mean f sergestids / mean depth range of sightings per dive at each site.
Figure 10.
Comparison of S. similis Density in Distance Increments from the Canyon Wall. This
graphs the results of 26 horizontal transects made perpendicular to the wall (up to 100
m from the wall). The shaded region shows results for all transects at all depths. The
transects are also separated into two depth ranges (340-420 and 420-510 m) and
graphed for further comparison.
Figure 11.
Line Graph of Depth Increment Density Totals for Day vs. Night Dives. Density, given
by total 4 sergestids / total min, is plotted for the CA-CS and H9O Column site day
dives and for the H9O Column site night dives. Night dive results come from two
dives in March 1989.
Figure 12.
Comparison of Total Densities at H90 Column Site: Day vs. Night Dives. (This figure
is constructed like Figure 10.) Night dive results come from two dives in March 1989.
Figure 13.
Comparison of Horizontal Transects Paralleling the Canyon Wall at 100 m Off vs. At
the H9O Column Site in the Center of the Canyon. The graph shows overall density
results for all transects as well as results for the transects split into two depth ranges
(300-400 and 400-500 m). Located under Table 4.
Figure 14.
Sergestes similis Depth Distribution as Determined by Sightings During ROV Descent:
Night Dives at H9O Column Site. A plot (compare to Figure 4) for two night dives
03/09/89 and 03/22/89. Located with Table 7.
Table Legends
Table 1.
Depth Increment Totals for All Dive Descents at C4-CS Site and H9O Column Site.
"Mean Calculated Range Density" is the average value of the f sergestids/ min density
calculated for each dive in that depth range. "Highest" - "Lowest Range Density'
gives the range of values drawn in black in Figure 6.
Table 2.
Data for Examining Vertical Patchiness. Column 4 is graphed in Figure 8. The first 23
dives listed are from the H90 Column site. The last 15 dives are from C4-CS. The
final column is the total 4 sergestids sighted / the greatest depth reached by the ROV
for each dive.
Table 3 (a & b).
Raw Data for Horizontal Transects Paralleling the Canyon Wall at 100 m Off and at the
HoO Column Site in the Center of the Canyon. This shows sergestid counts, f min in
transit, and densities for a total of 24 transects.
Table 4.
Overall Totals for Horizontal Transects Paralleling the Canyon Wall at 100 m Off vs. At
the H9O Column Site in the Center of the Canyon. The density totals from this table
are graphed in Figure 15.
Table 5.
Overall Totals for Horizontal Transects Perpendicular to the Canyon Wall. These
results are graphed in black in Figure 10.
Table 6.
Totals for Horizontal Transects Perpendicular to the Canyon Wall Split into Two Depth
Ranges. Transects were separated into those at depths 340-420 m and 420-510 m.
Results are graphically compared in Figure 10.
Table 7.
Overall Data for Night Dives. The final column (Overall) gives either the total or
X, the average, for the two night dives made at the H»O Column site. The dive on
03/09/89 took place three days after new moon, and the dive on 03/22/89 occurred
two days after full moon.
Table 8.
Totals for Observations of Interactions of S. similis with Benthic Organisms. This totals
the observations listed in Appendix 4.
Table 9.
Noted Instances of S. similis Foraging/Scavenging Behavior. All noted sergestid
sightings 03/09/89 -05/14/91 were considered. These are the best examples of
apparent scavenging in detritus.
Table 10.
Noted Instances of S. similis Schooling Behavior. All noted sergestid sightings
03/09/89 - 05/14/91 were considered. These are the best examples of what may be
considered schooling, all near-bottom.
Table 11.
Highest Noted Relative Densities of S. similis. All sergestid sightings from 03/09/89-
05/14/91 were considered. The three listed observations had the video camera set for
wide angle viewing, as in all transects reported.
Table 12.
Descent Speeds Calculated for S. similis. These speeds were calculated by noting
change in depth reading on the ROV/change in time.
Table 13.
Results of Two-Sample, Two-Tailed t Tests. Comparisons were made between mean
densities for depth increments at the C4-CS and H9O Column sites, between mean
densities for horizontal transects paralleling the wall and at the H9O Column site, and
between mean densities for distance ranges up to 70 m from the wall for horizontal
transects perpendicular to the wall.
Table 14.
Results of Two-Sample, Two-Tailed Mann-Whitney Tests. Selected comparisons made
with t tests were repeated with this robust nonparametric test.
Appendix Legends
Appendix 1.
Raw Data for Each Dive Descent. This table shows all data obtained for 15
C4-C5 Site and 23 H9O Column Site dives 04/26/89 -05/07/91. For each depth
range, the total 4 of sergestids sighted is the top f, the total f min spent
in transit is the middle f, and the density calculated by f sergestids / min
is the bottom ft.
Appendix 2.
Overall Data Results Table for C4-CS and H9O Column Dives. Values from this
table are graphed in Figure 9.
Appendix 3.
Raw Data for Horizontal Transects Perpendicular to the Canyon Wall. This table
presents data for 26 transects. For each 10 m distance range from the wall,
the top 4 is the number of sergestids sighted, the middle f is the total f
min in transit, and the bottom f is density given by f sergestids/min.
Appendix 4.
Individual Observations of Interactions of S. similis with Benthic Organisms. All dives
03/09/89 - 05/14/91 were considered.
Appendix 5.
Close-up Observations Holding an Approximately 25 cm Screen Width. These
observations are biased by the apparent attraction of S. similis to ROV lights.
20
o
5
0
.

22





f





0



2


9
o0




8
FIGURE 2
DEPTH VS. TIME PLOT of First Sergestid Sightings for
All Dives 03/20/89 - 02/28/91
500
y = - 13.022 + 17.355x R°2 = 0.182
400-
HEE
HE
E
E

mE.
EE


300 -

En

200
E
100
22 24
18
16
20
Time (GMT)
Pacific Standard
22
8
Depth (m)



Depth (m)
kaataa-
.



S
23
Depth (m)

3--
7 2c.
F.  :r= |— —1:-
34 —e
Fr:::-
Xm.
F.-i¬
8 . :r:o——
3 :2-
Zx-4-
3e-
2 1--

3--

e-
—-
Date
01/07/91
02/28/90
03/26/90
04/18/91
05/23/90
05/06/91
06/27/89
06/04/90 -
06/12/90 -
09/12/89
09/29/89
09/10/90 -
11/12/90
12/20/89 -
12/03/90 -
3: :
99
00
210
24
Depth (m)
584
2
3
X+-
* . .
3
3. . * . - - -
3.
... . —

. -.
3.-
Fr -X. 3429- .
.-0
. ... .
24.4 .
.
Xi2
3.;— 79

+*-
gax¬
34:—
3 -3-- )-
H--
Date
01/25/90
01/22/91 5
02/28/91
03/13/90
03/19/91 :
04/26/89
04/30/90
05/02/89
05/22/90
05/07/91
06/15/89
07/16/90
07/23/90
08/06/90
10/03/89
10/10/89
10/01/90
11/15/89 2
11/08/90 2
11/13/90
12/05/89
12/11/90
12/20/90%
3 : : .
20
25
al

2
3
20
Density (# Sergs/Min Descent)
o- usooooo

t


A




ttttat


ledett

—
S
8S
5 0
0
19 +
18
17 +
16 +
15 -
14 +
13 +
124
11
10 +
94
8
+
6
5
4 +
34

t

oERR
0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-1010-11 11-12 12-1313-1414-15
Overall Density (Sergs/min), for Dive
C4-C5 Wall Site
H0 Column Site
FIGURE 7
Frequency Distribution of Overall Density (Sergs/min)
for C4-C5 and HO Column Dives 1989-1991
DD
o2
05
06/15/
0/03/8
0/0/
11 15/
12/058
01/2590
03/13/00
Ou30

01/1/
01/23/00
08/04
10/01/00
1/09/0
1/13/00
2/1/0
ao
O2
0228/1
03/19/
05107
Oa7
0/12/82
0
o

028/
03/26/0
05/23/0
Oor0
00 12/20
09/9/
/20
2/03/
0/07/
O13/UE
05/00
A for H.O Columa
1 for Ct-C5 100

0
DO
1
Patchiness Density (Sergs/m)
28
2
3

2
Density (Sergs/min OR Sergs/m)
Z

33
20
"Density" (# Sergestids / Min)
2

2




S





—33
3
—33
—33
3
33

30
31
FIGURE 11
Day vs. Night Dives
Depth Ronge Densities (Sergestids/Min)

5
kata

o

—

250-300
100-200
200-250
0-25
25-100
Depth Ronges (m)
+ C+-C5 Site. 9 Overall Total (DAY) Q H,O Column Site (DAY) A 4,0 Columo Site (NIGHT)
FIGURE 12
A Comparison of Total "Densities"
At H,0 Column Site DAY Vs. MCHT
0.4 -
7
0.35

as

oat



a
4
V
os
LA



#r Sergs
Total  Sacgs
1 Depth Range ef Sigrtings /1 Grestert Dapth ek Oie
Total w Min
0 Column (NICHT)
H30 Column (DAY)
(u: average value)
Depth
Range (H)
0 - 25
25 - 100
100 - 200
200 - 250
230 - 300
300 - 350
350 - 400
400 - 450
450 - 500
Totals fo
0 - 550 »
Depth
Range (4)
0 -
25 - 100
100 - 200
200 - 250
250 - 300
300 - 350
350 - 400
400 - 450
450 - 500
Totals for
0 - 550 "
Depth
Range (n)
0 - 25
25 - 100
100 - 299
200 - 250
230 - 300
300 - 350
350 - 400
400 - 450
450 - 500
Totals for
0 - 550 n
TABLE 1
H0 CUn Total Total Sergs
ies ean Calculated
Louest
Jotal Rin of Sergs Total Hin Per Range Range "Density
Range "Density“
Sergs Min
12
23
343
0.035
0.049
5 10
0.035
23
0.395
49
0.193
0.672
0.628
1.73
178
0.983
181
2.138
136
117
0.86
1.852
35
0.771
0.779
1638 578
0. 353
0.846
ves ean alculated
touest
C4- Total lotal Sergs
Per Range Range "Density“ Range "Density
Total flin of Sergs Total Hin
Ses/in
44
0.2
0.097
2.375
56 132
2.357
15
9.868
500
7.463
13.343
532
9.333
128 887
0.556
6.93
9.339
1.886
49
1.265
62
1.567
53 56
1.057
4.286
3.85
567 2183
OUERALL otalotaleg
Jotal fin of Sergs otal fin
19
151
0.048
21
142
0.416
1.71
549
2.091
709
J. 453
0.968
0. 943
1.252
2205 2761
32
Highest
Range "Density"
0.889
27.333
10.667
2.2
27.333
Higtest
Range "Density
46.333
46.5
33.333
46. 333
TABLE a
Date of
Total
Depth Range (n! Jotal u Sergs
Shallouest
Deepest
Createst
Jotal 4 Sergs
Dive Sergs/Descent of Sightings
Depth Range Sighting (n) Sighting (n) Depth Reached Greatest Depth
04/26/89
140.36
448. J6
0.085
0.027
05/02/89
415.73
71.75
0.056
0.009
06/15/89
275.53
0.29
404.77
275.5
0.197
10/03/89
56.14
0.214
415.14
416
0.029
10/10/89
16.15
0.31
175.87
391.97
0.012
11/15/89
47.08
0.935
405.08
0.107
12/05/89
30.78
357.84
388.62
0.046
01/25/90
101.98
0.235
398.98
0.060
03/13/90
152.4
0.039
73.08
220.68
0.014
04/30/90
299.92
299.97
0.002
05/22/90
0.096
428.55
0.028
07/16/90
188.06
0.138
194.46
382.57
0.066
07/23/90
170.99
0.018
182.88
353.87
0.007
08/06/90
118.26
0.059
257.25
373.31
0.019
10/01/90
0.188
304.19
JJ6.19
0.018
11/08/90
202.03
498
0.874
484.63
0.335
11/13/90
137.16
0.189
435.0
317.9
0.097
12/11/90
134.65
0.342
466.63
0.094
12/20/90
62.48
0.352
318.82
381.J
0.058
01/22/91
99.06
0.04
333.45
432.51
0.009
02/28/91
53.59
0.075
257.56
911.13
0.03
03/19/91
201.77
438.9
0.02
237.13
0.009
05/07/91
248.11
453.85
0.077
205.74
0.041
06/27/89
50.6
0. 435
321.87
372.47
0.059
09/12/89
94.44
0.688
383.44
0.167
09/29/89
0.749
69.42
300
369.42
0.139
12/20/89
50
110.63
5.116
85
395.63
1.433
02/28/90
72.77
0.807
112.77
260
0.243
03/26/90
379.17
150.27
0.606
228.9
0.239
05/23/90
139.91
364.83
224.94
0.886
0.337
06/04/90
214.36
1.087
448.J6
0.320
06/12/90
77.42
0.827
285.9
363.32
0.176
09/10/90
105.46
0.313
263.35
J68.81
0.090
11/12/90
243.53
1.302
216.41
459.94
0.688
12/03/90
168
182.37
0.92
275.54
458.11
0.366
01/07/91
193.8
193.8
0.263
0.112
04/18/91
249.84
510.84
0.236
0.115
05/06/91
281.33
0.878
179.83
461.16
0.536
TABLE 3(a and b)
(a)
Horizontal Transects Paralleling Canyon Hall (100 n off)
Total
Total Density
Depth
Initial
Initial
Site Range (n) Jape I.D.
Frane Depth (n) * Sergs# Hin Sergs/Hin
line (CHT)
300-400 05/06/91/09
02:46:58:00
5.45
1.101
C4-C5
1849
1.83
5.797
C4-C5
300-400 05/06/91/12
03:55:45:00
28
1957
342
300-400 05/13/91/10
1.75
2130
03:06:05:00
NWall
3.281
400-500 05/06/91/02
C4-C5
00:38:00:00
457
8.23
1640
1.28
C4-C5
400-500 05/06/91/03
1658
00:57:03:00
455
2.57
01:17:94:00
2.63
N Wall
400-500 05/13/91/04
1736
440
01:55:50:00
400-500 05/13/91/06
2 3.42
0.585
K Wall
1812
(D) Horizontal Transects at HO Colur Site (Center of Canyon)
Total
Total Density
Depth
Initial
Initial
Range () Tape I.D. Tire (CHT)
Depth (n) * Sergs# Hin Sergs/Hin
Franie
300-400 08/18/89/09
04:07:57:00
11.75
1900
301
309-400 10/03/89/1
0.823
2059
0q:59:21:00
2.43
0.699
300-400
10/01/90/08
02:28:08:00
10.02
300-400
10/01790/09
3.77
1910
02:50:35:00
5.381
300-400
9.83
10/01/90/10
1917
02:58:20:00
300-400 11/19/90/05
01:25:29:00
10.07
11.321
2024
300-400 11/19/90/05
2.273
01:36:35:13
5.77
2038
300-400 03/19/91/08
1906
02:35:99:00
1.63
300-400 03/19/91/10
1.15
1954
03:24:13:00
300-400 05/14/91/03
1720
00:50:31:00
375
300-400 05/12/91/05
01:30:46:00
1801
98 10.22
9.589
400-500 11/19/90/06
01:46: 40:00
426
2056
400-500 11/19/90/06
420
01:56:57:00
9.7
5.135
2107
400-500 12/04/90/10
497
3.J
03:12:01:00
2129
400-500 12/11/90/06
1902
01:46:48:00
1.53
3.268
445
400-500 05/07/91/11
1953
03:32:05:00
0.89
3.37
400-500 05/14/91/06
01:51:08:00
410
1821
1.5
TABLE +
Depth Range (n)
Total Iransects
Average Depth (n)
Average line (CHI)
Total * Sergs
Total lin
Total « Sergs
Jotal  Hin
Tof Densities Cald
for ach Transect
FIGURE 13
5
A
300-400 m
Porolleling Wol
Xof densities calcd
tor each transect
Paralleling Canyon Mall 1100 n off)
At H.O Colunn Site (Center of Canyon)
300-400 400-500 Overall
300-400 400-500 Overall
11
342.36 434.5 374.88
375 459.75 423.43
1919
2007 1936
2005 1722 1832
189 156 395
34 90
59.21 29.62 88.83
12.03 18.56 30.59
J.192 5.267 3.884
2.826 2.155 2.419
J.388 3.4 J.392
2.299 1.609 1.905
59.589
41.321
Vr




400-500 m
Overoll
Al HO Column Site
Ronge of densities"
calc'd for each transect
35
3 a

.
.

*





88 2

3

2

8ata-
ktata-
a
2 3
a
a


3
s katakatataa
o
taaa
3
33

2

O
30
2 -
2 2

28

aaa-

aa-
S
.
2 3
8 £ 2
23
.

p 0
8 2 5
2
a-



.
.

8
oa
FIGURE 14
A
200
300
key
de sighrioo
.. muttiple (a*)
Mextent af dive
A
Night Dives
Total * Sergs
Total  lin
Total 4 Serqs
Jotal &am lin
Createst Depth
Reached (m)
Jotal 4 Serqs
Createst lepth (m)
Salloest
Sighting (n)
Deepest
Sighting (n)
Range (n) of
Sightings
Jotal 4 Sergs
Above Range (n)
Depth Range (n!
Actual Data?
0-25
25-100
100-200
200-250
250-300
TABLE 7
03/09/89 03/22/89 Overall
225
125
100
0.053
0.1
0.016
123 292 207.5 -X
+Serg.
9.016 0.034 0.034-7 daptk
77.7 54.09 -X
30.48
51.82 286.5 169.16 -X
21.34 208.8 115.07 -X
9.994 0.048 0.071-X
35 nin
15 min
20 nin
0 Sergs
0 Sergs
0 Sergs
0 nin
0 nin
0 nin
32 nin
92 nin
60 nin
5 Sergs
3 Sergs
2 Serg:
094 nin
054 nin
033 nin
72 nin
27 nin
45 nin
6 Sergs
6 Sergs
0 Sergs
222 nin
083 nin
0 nin
13 nin
0 Sergs
0 rin
13 nin
1 Sergs
077 nin
12823
28
aa-

6
sd
an
osnooo-oo0
2
5
10
5
-
3
15
5
2 2222
9 888
ooc
OGGN8S
CNNNEN
oooo
g
oooooc
ooo
O
ooo
—
.. .. .
o


—POOEN
oog
oooo¬
O
.. .. .. .. ..
o
o
o
* ** ** ** *
SNOPO
oo
OOOOOO
Gooo
o
OOo

.
NNOON
a:

22:
2 0
AA
AA
— —
voo
BBB

98
5


( ( —
3

1 -
zzzz
22:
SS.
o
58
ooo
boo
ENEEE
10
o00
oooo
OC
— — —
. . . .
888
SPON
o
o
0
O
OOO
2888
.. .. .. ..


.. .. .. ..
N
o
. .. .. ..


.. .* .*
OGN
ooc
o
.. .. ..
DOON
OOSA
O
NNAN
PEN
oo
. . . (
0
oo
G
02

SG2

2



—
2
3
5
o
9
- +
.
.
aaaa-
.

aatatav-
katataaaaaaaaa
5

8

28.
28
88
saaaaa.
2
388

22

ad
8aa88
888882
aa
o
3-


aa
aaaaa-



3-8

288a



2-

— —
—

2
2
a
aa
saa



a
sa-
d


ooo-
30


aaaaaa-

ooo



89.

11 12 21
-M
8
— —
N
/6
1

XI XI
—— —
"


S
35
82
2
2-
225


52
2
EESE
a
.
aataaaaaaoaa-


-
jmuumuuuu
aa
222288888828
32
E
2
7577787
aaaa-
aaa-
22z1
aaaaaa-
88888888888383
aaazaza2
doddadas.
a———

aaaaa-
— — —
a
---

8
-
.
88888.
5.

as
aaaaa-


Zuagsssas
a
a-
aaaaa-
aaa-
aa
a
a

38


-
aaiaaa
.
o
-
aa
28u8283.
283
oooo
2s-a
2

aa-
33




a
oao-
Sos
0.
ss
2
9
aaa
33003
*
13
TABLE 14
Nonparanetric Statistical Test Results
Hann-Uhitney lests
Explanation of Colum Headings
Sarple 1: first data set, Saple 2: second data set, HR: nean rank, n: nurber of values in a data set
U:  tines a value in sample 1 precedes a value in 2, M: sun of ranks for snaller sanole,
2: standard nornal deviate, 2-tailed p: probability level based on distribution of the score
Conparison
Sanple 1 Sarple 2
RR1 RR2 ni n2 U
1 2-tailed p
1. Uertical Distribution
Depth Range 350-400 n
H50 Colurm
C4-C5
14.61 25.43 22 15 68.5 381.5 -2.9869 0.0028
Depth Range 400-450n
H,O Colurn C4-C5
11.13
12.5 16
75 -0.4448 0.6564
Depth Range 450-500
H,0 Colum
5.33 6.8 6 5 11 34 -0.7336 0.4632
C4-C5
Density for 190 Colum
Dives 300-500 n vs
Al1 K0 Col. Horizont.
42.64 41.94 67 17 560 713 -0.1074 0.9145
Horizontal Transects at Descents Transects
H,0 Colunn Site
2. Horizontal Transects
Depth Range 300-400
7.09 3 11 12 27 -0.7482 0.4543
Parallel to
at H.0
Canyon Mall Col. Site
Depth Range 400-500
Parallel to
at K.0
5.83 4 6 10 20 -0.4317
0.666
Canyon Wall
Site
39.17 +4 k5 440 575 -1457 0.3448
Dapih Kange. 300-500m

41.07
23.9 26 26 270.5 756.5 -1.2365
Distance Ranges fron Wall
0-10
20-30
0.2163
0-10
30-40
19.36 26 25 159
32.39
-3.1689
0.0015
0-10
40-50
33.42
-J.6682
0.0002
26 25
18.28
10-20
30-40
28.48
24.36
-1.0091
0.3129
26 7.
10-20
40-50
-1.5425
29.08
22.8
0.123
40-50
J0. 96 20.84
-2.4629
20-30
0.0138
50-60
20-30
-1.3942
0.1632
22.37
17.04
133.5
238.5
30-40
50-60
172.5 277.5
-0.0797
0.9365
20.1
19.82
166 -0.5577
30-40
80-90
18.56 16.6
0.5771
Tests were made using the SPSS Statistics software.
Hy: densities compared are the same
Two-tailed hypotheses:
H: densities compared are different
Reject H if two-tailedp.05
15
APPENDIX 1
94/26/89 05/02/89 06/15/89 06/27/89 09/12/89 09/29/89 10/03/89 10/10/89 11/15789 12705/89
Date
Site
H,O Colurm H,O Colurin H,O Coluno C4-C5
CA-C
C4-C5 H0 Colurn H0 Colunn H,0 Colur H,O Colunn
440
Createst Depth
470
406
373
390
416
410
392
Depth Range (n)
0-25
8



0
0
0
25-100

100-200
0 0 0.889 0 0
0 0
0

200-250
16

0
o
3

250-300
0

5

0
23
918

300-350
25
0.143
350-400
0.048
10.667
3.375
5.25
0.556
400-450
o
Total * Sergs
Total  lin
Density (K/nin)
0.167
1.63
1714 0.07
2.6 1.793 0.126
1.86 1.467
0
5
0.285
Date
Site
Createst Depth
Depth Range (n)
0-25
25-100
100-200
200-250
250-300
300-350
350-400
400-450
Totaltsen
Totol tAin
Densttu
APPENDIX 1 (CONTINUED)
17/20/89 91/25/90 02/28/90 03/13/90 03/26/90 04/30/90 05/22790 05723/90 06/04/90 06/12/90
C4-C
C4-C5 H.O Colum C4/C5 H,O Colurn Ca-C5 H,0 Colurn H,0 Colum Ca-C5
C5-C4
368 448
409
431
381
395 402 375 441
0
k

23
28
0
5
0
*

15
5
1.5
0 0 0.125

0.02
20
245
0.1 0 1.5
9.6
6.667 0.333 5.167
0.286
3.5
32.5
8.5
0.17
0
46.5
2.129
100
100
453
0 33.333
0.07
18.12
3
0.775
2.667
0
12
124
566
10.13
4.43
6.0 0.18
1.717
14.15 0.6 3.957 0.075
2.783
Bate
Site
Createst Depth
Depth Range (n)
0-25
25-100
100-200
200-250
250-300
300-350
350-400
400-450
450-500
Total & Sergs
Total & Hin
Density (H/nin)
47
APPENDIX 1 (CONTINUED)
97(16/20 97(23/90 08/06/90 09/10/90 10/01790 11/08/90 11712/90 11/13/90 12703/90 12/11790
C4-C5
H.0 Colurm H,0 Colum H,O Coluin C4-C5 H,0 Colun K,0 Colun C4-C5 H,0 Colum Ca-C5
459
498
401
376
0
kk k k
12
o 5
6 o 0 0
4
20
0 0
6

0.033
0.00
90
8
3


139
6.25
46.333
7
0.083
0.857
0.625
9.75
0.111
1.333
7.33
1.077 0.020
2.8 0.333
0.15
1.778
J. 43
1.48
0.167 0.462 9.5
0.14
1.07
1.416

0.416
2 0.286
0.333 0.333
317
138
0.292 2.754 0.63
4.594
135
9.942 0.074 0.868 0.043
0.321
Date
Site
Createst Depth
Depth Range (n)
0-25
25-100
100-200
200-230
230-300
300-330
350-400
400-450
450-500
500-550
Total * Sergs
Total &am Hin
Density (K/nn)
APPENDIX 1 (CONT'O)
12/20/90 01/01/91 01/22/91 02/28/91 03/19/91
04/18/91 05/06/91 05/07/91
C4-C5 H30 Colun H30 Colum H,0 Colum C4-C3
C4-C5 H,0 Colunn
H,O Colunn
381
470
514
461
0
0
0 0
0 0 0 0

0 0.069
0
9

8
0
31
17.5
0
0.333
22.667
0.083
0
29.5
0.091
0.037
0.571
17.5
0.429
0.167
0.091
0.08
0.667
7.4
0.5
1.833
4.5
0.143
0.71
0.417
206
1.7
0.289 0.019
0.67
0.514
11.227
0.051
APPENDIX 2
C4-C5
Overall
H,O Column
38
15
23
Total + Dives
2761
2183
578
Total + Sergs
on All Dives
72.66
145.53
25.13
Average + Sergs
Sighted Per Dive
567
2205
1638
Total Min for
All Dive Descents
58.03
37.8
71.22
Average Time of
Dive Descent
1.252
3.85
Total+ Sergs
0.353
Total Min
2.152
4.323
0.736
Density calc'd
for Each Dive
(Sergs/min)
01-7.375 .67-14.15 .01-14.15
Range of Densities
calc'd for Dives
(Sergs/min)
421.22
412.4
426.96
Average Greatest
Depth of Dive (m)
0.172
0.353
0.059
Average + Sergs
4 Greatest Depth
135.34
151.75
124.63
Depth Range of
Sergs Sightings
0.537
0.959
0.202
Average + Sergs
A Depth Range of
Sergs Sightings
(Listands for average value)
APPENDIX 3
Horizontal Iransect Data
Distence Ronges From Wall cm)
Site Date Bepth (nl | 0-10 | 10-20 | 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100
2 Sergs
2 Sergs
C4-CS 01/20/89 366 1 Serg
5 nin 5 nin 9 nin  9 nin 1.27 nin
2 nin 0 mn 2.22 mn 0 nin 1.57 nin
C4-C5 09/29/89 367 2 Sergs 2 Sergs 4 Sergs 2 Sergs 3 Sergs
6 nin
4 min .7 nin 6 nn
6 nin
3min 2.86 mn 6.667 mn 3. 333 nin 5 nin
C4-CS 10/24/89 344 12 Sergs 31 Sergs 3 Sergs 7 Sergs
6 nin .8 nin
5 nin
6 nin
5 min
24 min 31.67 nin 3 nin 8.75 nin 0 nin
430 2 Sergs .42 nin 2 Sergs
5 nin
5 nin
42 nin .4 nin .42 nin
4 nin
4.76 nin 0 nin 4.76 nn
0 nin 0 mn 0 nin
5 Sergs 3 Sergs
2 Sergs
Pt. Joe 01/10/90
1.25 nin 1.12 nin .55 nin
4 nin 2.68 nin J. 636 mn
2 Sergs 3 Sergs 7 Sergs 6 Sergs 2 Sergs
372 | 4 Sergs | 4 Sergs | 4 Sergs
3 Sergs
C4-CS 03/26/90
4 rin .37 nin
4 nin 4 min
4 nin
75 nin .38 mn .42 mn
4 nin
5 nin 7.5 niä 17.5 nia 15 nin 5.41 nin
3.333 min 6.9 nin 9.32 nin 7.5 nin
1 Serg
1 Serg
1 Serg
1 Serg 1 Serg
C4-C5 08/07/90
2 Sergs
6 nin 16 trin 5 mn 55 nin 64 nin 65 nin
1 nin
6 nin 6 nin
3.333 min 0 nia 1.67 mn 1.67 min 1.82 nin 1.87 mn 0 nin 0 nin 1 nin
2 Sergs 1 Serg 1 Serg
C4-C5 04/18/91
1 Serg 2 Sergs
1.6 nin 1.6 mn 1.6 nin 1.6 nin 1.6 nin 1.6 nin 1.6 nin 1.6 min 1.6 nin 1.6 mn
623 min | 1.25 mn 1.25 nin 625 nin .625 nin 0 nin 0 nin 0 nin 0 ma 0 nia
1 Serg 5 Sergs 3 Sergs J Sergs
5 nin
7 nin 2.5 nin .8 nin
5 min
2 min 7.14 nin 1.2 nin“ 3.75 nin 0 nin
509 3 Sergs 3 Sergs 2 Sergs
2 nin
2 nin
1 nin
2 nin
1 nin
0 nin
0 nin
3mn | 3 mn | 1 mn
450 3 Sergs
1 Serg
1 Serg
1 Serg
7 nin 6 nin
6 nin
8 nin.7 nin
3.75 nin 0 nin 1.43 nin 1.667 nin 1.667 nin
1 Serg 1 Serg 1 Serg 1 Serg
1nin. 1.5 nin 1.5 nin 1.5 nin
1.5 nin
0 nin
1 nin 667 nin .667 nin .667 nin
1 Serg
427 1 Serg 1 Serg
1 nin 1.5 nin 1.5 nin 1.5 nin 1.5 nin
1 nin 667 nin | 0 nin 0 nin 667 nin
1 Serg
1 Serg
1 Serg
1.5 nin
1 nin 1.5 nin 1.5 nin 1.5 nin
0 nin 667 nin 667 nin 0 nia 667 nin
50
APPENDIX 3 (continued)
Distance Ranges from Wall (m)
19-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100
Site Date Depth (n) 0-10
436 2 Sergs
2 Sergs 6 Sergs 2 Sergs 1 Serg
C4-C5 03/06/91
2 Sergs 1 Serg
9 nin 9 nin 1. 433 nin
6 nin .65 nin .7 nin
6 nin 3 nin
5 nin .9 nin
3.333 nin 0 nin 4 nin 1 111 nin 0 nin 2.222 nin 4.2 nin 3.333 nin 1.54 nin O nin
5 Sergs
37 nin 47 nin
52 nin &am2 nin 52 nin .32 nin
3 nin
9.62 nin 0 nin 0 nin 0 nin
O nin 0 nin 0 nin
1 Serg
1 Serg
1 Serg
1 Serg
1 Serg
1 Serg
48 nin 55 nin 47 nin
1.03 nin .88 nin .62 nin
5 nin
47 nin 63 nin 47 nin
97 nin 1.14 nin 1.61 nin
0 nin 2.13 nin 0 nin 0 nin 2.08 nin 0 nin 2.13 nin
1 Serg
344
1 Serg 2 Sergs
2 Sergs 4 Sergs 6 Sergs
1 Serg
6 nin .53 nin
7 nin
8 nin .57 nin
4 min
47 nin 62 nin .75 nin
43 nin
2.5 nin 7.02 nin
15 nin 0 nin 2.13 nin 1.61 nin 2.67 nin 0 nin 0 nin 1.43 nin
1 Serg
1 Serg 2 Sergs
342 2 Sergs
2 Sergs
55 nin
Vnin 38 nin 48 nin .47 mn
27 nin .28 nin .28 nin
33 nin
0 nin
Onin 1.82 nin
0 nin
3 nin 5.26 nin
7.41 nin 0 mn 7.14 nin
5 Sergs 3 Sergs
N. Hall 05/13/91
1 Serg
1 Serg
2 Sergs
2 Sergs
87 nin.53 nin
73 nin .87 nin .73 nin 43 nin
4 nin
6.85 nin J.45 nin 1.37 nin 4.65 nin 2.5 nin 2.J nin 0 nin
3 Sergs 2 Sergs 6 Sergs 3 Sergs
1 Serg
38 nin 72 nin 7 nin 67 nin 75 nin 58 nin .75 nin .83 nin .42 nin .83 nin
7.89 nin 2.78 nin 8.57 nin 4.5 nin 1.33 nin 0 nin 0nin 0nin 0 nin0 nin
1 Serg 1 Serg 1 Serg
2 Sergs 1 Serg
7 nin 83 nin 47 nin 55 nin .62 nin
68 nin
1 nin 57 mn 83 nin .75 nin
1 nin 1.73 nn 1.2 nin 1.33 nin 0 nin 0nin 0 min 0 nin 0 nin
2.94 nin
2 Sergs 1 Serg
1 Serg
82 nin 5 nin 33 nin 47 nin 53 mn .23 nin .33 nin .28 mn .37 nin 43 nin
2. 44 nin | 2 nin 2.86 nin 0 nin 0 nin 0 nin 0nin 0nin 0 nin 0 nin
1 Serg
2 Sergs 1 Serg
1 nin
67 nin 93 nin 88 nin 68 nin
5 nin 1.28 nin
3 nin 1.08 nin 0 nin 0nin 0 nin 0 nin 1 nin
1 Serg
55 nin 87 nin .68 nin 72 nin .8 nin
0 nin 1.15 nin 0 nin 0 nin 0 nin
393 1 Serg 1 Serg 1 Serg
1 nin
63 nin 9 nin 1.1 nin 1.42 nin
1.59 nin 1.08 nin9 mn 0 nin 0 nin
APPenoix +
Initial
Site Jape I.D.
frane
C4-C5 03/28/89/06
01:54:38:26
91:54:57:14
01:55:01:04
C4-C5 03/28/89/11
03:30:53:01
03:38:38:24
C4-C5 03/31/89/04
00:54:44:24
01:02:20:29
C4-C5 96/27/89/02
00:30:17:14
C4-C5 09/12/89/16
05:29:12:15
05:33:02:03
NHall 10/26/89/09
01:14:93:03
01:27:00:02
NMall 10/26/89/05
01:30:18:25
01:35:49:22
01:56:10:19
N Hall 10/26/89/06
02:03:57:17
02:47:19:22
N Mall 10/26/89/09
92:47:53:02
02:48:33:18
02:50:23:00
03:07:33:14
Nuall 10/26/89/10
03:19:59:01
03:18:09:06
03:18:25:12
03:18:48:02
03:19:22:00
CA-C5 05/23/90/04
01:14:31:04
C4-C5 05/23/90/05
01:23:07:19
01:25:93:19
01:27:42:04
01:27:56:12
01:28:02:17
91:28:07:16
01:29:01:15
92:39:58:02
CA-CS 06/12/90/08
00:37:59:08
Carnel Cn 07/24/90/02
C4-C 09/10/90/05 01:40:37:08
01:40:51:19
01:43:08:11
01:43:11:00
01:43:49:12
01:44:32:03
01:44:37:04
C4-C5 09/10/90/07
92:19:09:10
02:19:23:08
02:19:26:10
Pt. Joe 09/24/90/07
92:16:12:08
02:21:01:29
Sergs
Depth (n) Involved
367.3
367.1
367.2
N/R
N/A
363.3
369.1
336.1
336.8
378.2
377.4
380.09
377.65
372.7
368.5
367.9
368.5
368.5
361.3
361.5
356.3
356.3
355.
357.5
357.8
356.6
356.6
356.6
356.6
356.6
340.2
200
352
369.4
369.4
369.4
341.68
341.68
Organisn
Jouched
rockfish
encrusting sponge
encrusting sponge
ses anenone
carnivorous tunicate
cat shark egg case
carnivorous tunicate
sea anetione
encrusting sponge
sea anenone
sea anenone
ses anenone
upright sponge
sa anetione
encrusting sponge
rockfish
bottle-brush sponge
sa anenone
bottle-brush sponge
bottlebrush sponge
holothurian
holothurian
cat shark egg case
sea anenone
encrusting sponge
starfish
sea anenone
upright sponge
upright sponge
encrusting sponge
fish
upright sponge
ses anenone
gea anenone
encrusting sponge
crab
gorgonian
octupus
octupus
starfish
starfish
starfish
octupus
sea anenone
upright sponge
sa anenone
starfish
starfish
* Sergs
That Dart
52
5
—
85


8
8 5
-N
Sasae

3
a
n
Soe
aa
80
kaaa.

5
53