(*Please Note: This initial report was written based on
available data immediately following the 1999 Pensacola Great
American Fish Count. As no other members had yet turned in their
survey forms, the report was based soley on the data collected by
Field Station founders Greg Bunch and Danielle Dowdy. In
addition, the GAFC dives were focused on one site at the request
of Mr. Goodman. Therefore, in-depth details were recalled in this
report that are not part of the REEF fish identification program.
Subsequent reports will differ in format as the availability of
information changes.)
Dear Trey:
Enclosed is our survey report for Blackwater Bridge Rubble Site
15-G along with printouts of some photos of the life on it. The
report was compiled from data collected during our dives on July
11 and 15. Also included are copies of the REEF optical scan
sheets which contain the raw fish census data. We have requested
for you a copy of the REEF survey methods book, which provides
details about the collection, statistical analysis, and
application of REEF data. We'll have that to you as soon as we
receive it from REEF headquarters.
Keep in mind that the report is based only on our initial five
dives on site 15-G. However, even these few dives provided us
with a good overview of the site and the life it harbors. We are
excited about continuing and expanding our monitoring efforts on
this and other sites.
If you have any further questions, please feel free to call or
email.
Thank you very much.
Most sincerely yours,
Danielle Dowdy and Greg Bunch
Survey Report for Escambia County Artificial Reef Site
Blackwater Bridge Rubble Site 15-G
Latitude 30° 11.800' N
Longitude 87° 14.170' W
Dates of survey: July 11, 1999 and July 15, 1999
Surveyed by: Greg Bunch and Danielle Dowdy
Method: 5 open water SCUBA dives were done on the site. Bottom
times were as follows:
Date_____Start time____Max depth (feet)____Bottom time (minutes)___
Diver_
7/11/99..........10:45......................78......................................45.....................G.
Bunch
7/11/99..........10:45......................78......................................45.....................D.
Dowdy
7/11/99..........12:27......................77......................................38.....................G.
Bunch
7/15/99..........10:28......................78......................................38.....................D.
Dowdy
7/15/99..........12:46......................77......................................36.....................D.
Dowdy
Visual fish surveys were performed using the Roving Diver
Technique (RDT) employed by the Reef Environmental Education
Foundation (REEF) to record species and abundance. Also, general
environmental conditions of the artificial reef were observed and
noted.
I. Fish census data
As per the REEF survey method, all positively identifiable
species were recorded, and a relative abundance code was assigned
to each. The abundance codes were assigned as follows:
(S)ingle.........................1 individual, (M)any..................................11-100
individuals
(F)ew................2-10 individuals, (A)bundant....................more
than 100 individuals
Common name____________Proper name______________Abundance code
Seaweed blenny..............Parablennius marmoreus...................................A
Tomtate.............................Haemulon aurolineatum.....................................A
Cubbyu.............................Equetus umbrosus.............................................M
Blue angelfish...................Holacanthus bermudensis.................................F
Whitespotted soapfish.....Rypticus maculatus............................................M
Gray snapper...................Lutjanus griseus.................................................F
Slippery dick.....................Halichoeres bivittatus.........................................M
Belted sandfish................Serranus subligarius..........................................M
Spotfin butterflyfish .........Chaetodon ocellatus...........................................F
Cocoa damselfish............Stegastes variabilis............................................M
Great barracuda..............Sphyraena barracuda.........................................S
Purple reeffish.................Chromis scotti.....................................................M
Leopard toadfish.............Opsanus pardus..................................................F
Yellowmouth grouper......Mycteroperca interstitialis....................................F
Greater amberjack...........Seriola dumerili....................................................M
Spanish mackerel............Scomberomorus maculatus.................................M
Yellowtail reeffish...........Chromis enchrysurus..........................................S
Barbfish...........................Scorpaena brasiliensis........................................S
Sheepshead....................Archosargus probatocephalus............................S
Twospot cardinalfish.......Apogon pseudomaculatus..................................M
Bank seabass..................Centropristis ocyurus..........................................F
Planehead filefish.............Monacanthus hispidus........................................F
Atlantic spadefish............Chaetodipterus faber..........................................M
TOTAL POSITIVELY IDENTIFIED SPECIES: 23
Also observed were 6-10 small grouper in the 12-16" overall
length range. These could not be positively identified, but are
most likely Scamp (Mycteroperca phenax.) 3-4 other grouper were
observed which, although these also could not be positively
identified, appeared to be Gag (Mycteroperca microlepis.) These
included one large individual, which was 2.5 - 3' in overall
length.
II. Observations of fauna
On many levels, the fishes identified showed a great diversity.
Benthic species, such as Seaweed blennies (Parablennius marmoreus)
were extremely prevalent, as were coral reef species such as
Tomtate (Haemulon aurolineatum.) Other reef species included the
Cocoa damselfish (Stegastes variabilis), all of which were
extremely small (less than 1") juveniles, as were the Purple
reeffish (Chromis scotti) and Yellowtail reeffish (Chromis
enchrysurus). The site seems to harbor a significant population
of young juveniles. Constantly present slightly shallower in the
water column above the site were Spanish mackerel (Scomberomorus
maculatus.) Also present were extremely large schools of
unidentified baitfish, which hovered in close proximity to the
structure. A school of 20-25 young Greater amberjack (Seriola
dumerili) was fairly constant on the 7/11 dives. The individuals
within this school were mainly young animals, about 18" in
overall length. On the second dive of 7/11, three larger
individuals were observed in the school, about 30" overall
length.
Various other animals were also apparently taking refuge at the
site. Sand dollars were numerous on the bottom around the
structure. Shells and shell fragments were evident, indicating
the probable presence of gastropods and bivalves, although
sightings of live mollusk specimens were limited to only one
large octopus observed by other divers. Additionally noteworthy
is the fact that the site did contain several clusters of
gastropod eggs. Also on 7/11, three elasmobranch eggs were found,
which appear to be from a clearnose skate (Raja eglanteria.) As
described in the 'environmental observations,' a variety of
species from the phylum Cnidaria were present as well.
III. Environmental observations
July 11, 1999: Visibility at depth was estimated to be 40'.
Little to no current was present at depth. From the surface to
approximately 30', there was a moderate (less than 1 knot)
current, and visibility was greatly reduced due to heavy
planktonic concentrations. Considerable numbers of small stinging
jellyfish as well as comb jellyfish were present, in addition to
smaller cnidarians. Wave heights were 2-3'. Water temperature on
the surface was 84°F, at depth 81°F.
There was no evidence of human refuse (cans, bottles, etc.)
observed. One grouper, most likely a Gag (Mycteroperca
microlepsis) was observed trailing a section of fishing leader
from its mouth. One lead fishing weight was seen on the site.
July 15, 1999: These dives were conducted on the same site, but
slightly east of those from 7/11. Visibility on this day was
reduced to 20', with increased planktonic biomass and weak to no
current. Wave heights were 1.5-2'. The number of stinging jellies
was lower than on 7/11. Water temperature was approximately 80-81°F
at the surface and 76-78°F at depth. On the second dive, we
observed a section of the site which had a pile of bridge rubble
with relief up to about 65' and an area of sunken culverts in one
spot. Here a single beer can was found.
IV. General site observations
We estimate that the structure exhibits 85% coverage of heavy,
healthy barnacle growth, with light algae over most of the
barnacles. Approximately 15% coverage is encrusting sponge.
Purple sea whips and a yellow sea whip, all of which seem to be
healthy, are present in those parts of the reef not directly
exposed to currents. The barnacle/algal substrate supports a
thriving community of benthic fishes, providing shelter for many
very small juveniles. In addition, the site harbors a noticeably
large grouper population, the vast majority of which are also
juveniles.
V. Conclusions
Preliminary observations are that the site serves as a healthy,
thriving reef community. In spite of only having been down 2
years, it exhibits many of the characteristics of sites (such as
Three Barges) which were sunk decades ago. It supports a
significant benthic community, large numbers of juveniles, a
constant baitfish population, and attracts transient pelagic
predatory fishes like Spanish mackerel (Scomberomorus maculatus)
and Greater amberjack (Seriola dumerili.) While it lacks the
dense growth of sea whips and other invertebrates, they are
present in numbers consistent with the young age of this site.
The area seems to be very receptive to the use of the bridge
rubble in assisting the establishment of a diverse marine
environment.
VI. Future study
We would like to continue to monitor this and other sites on a
regular periodic basis. Further goals are to conduct video
transect and possibly repetitive still photographic records.
Mapping the reefs surveyed is a desired strategy and would be
beneficial to further studies. Also, quadrat counts could be
utilized to establish baselines for benthic coverage density and
species diversity.
Please email all questions to info@reefngom.org.