11th ICRS Abstract book - Nova Southeastern University

22.871
Rotary Time-Lapse Photography: A Non-Destructive Technique For Fish
Population Assessment
Ian MACDONALD* 1 , Doug WEAVER 2
1 Physical and Environmental Sciences, Texas A&M University - Corpus Christi, Corpus
Christi, TX, 2 Coastal and Marine System Sciences Program, Texas A&M University -
Corpus Christi, Corpus Christi, TX
We describe application of an autonomous digital camera system for estimating fish
population size, habitat fidelity, and behavior. A 5 megapixel digital camera and an 120
watt/sec strobe are co-axially mounted on a rotating pedestal inside a thick-walled glass
tube (i.d. 12 cm). A programmable controller operates the camera and a stepper motor,
which rotates the pedestal. At preset intervals or specific times the camera takes a picture
with synchronous strobe and the pedestal rotates a specified number of degrees (e.g. 36°);
rotation is unimpeded and can continue an indefinitely or reverse. Typically, 10 images
complete a 360° rotation and can be viewed as separate files or fused as a panoramic
image of deployment site. Power is supplied by an internal battery, mounted on the
pedestal, or an external battery connected through a slip-ring.
We tested this system on the Flower Garden Banks in the Gulf of Mexico. The
deployment site was the edge of a large sand flat on the main reef crest at 28 m depth.
Images were collected at 18 min intervals over a 23 day deployment, totaling 1840
images and 184 rotations. Effective visibility was 8 m from the camera during daylight
and 5 m during nighttime. Biofouling on the glass tube began to cause noticeable
degradation of image quality after approximately 14 days. A significant fraction of the
common reef fish known from the Flower Gardens were identified and enumerated,
providing details of behavior patterns and habitat preferences.
22.872
The Use Of Abc Curves As Health Indicator For Reef Fish Communities
Sachiko HAYASAKA* 1 , Horacio PEREZ 2
1 Ecología de arrecifes, Unidad de Investigación del Centro de Ecología y Pesquerías,
Boca del Río, Veracruz, Mexico, 2 Ecologia de Arrecifes, Unidad Investigaciòn del
Centro Ecologìa y Pesquerìas, Boca del Rio, Veracruz, Mexico
According to Warwick (1986), the health of benthic communities can be measured by
using Biomass - Abundance Curves (ABC). Under unpolluted conditions, biomass will
become dominated by few large species, which are in equilibrium with available
resources. When polluted conditions are present, the numerical dominants are smaller
species which are out of equilibrium with resources. The curves for unpolluted
communities are represented with biomass curve above the abundance curve. As
pollution increases the curves become overturned. The purpose of this project is to test
these curves to evaluate their potential use on reef fish communities. We studied eight
reefs, five from the North area which are near the coast and urban activities (Anegada de
Adentro, Verde, Pájaros, Sacrificios, Ingeniero) and three from the South area, far away
from the coast (Santiaguillo, Enmedio and Blanca) for one year starting July 2006. The
censuses were visual at two depths (3 and 15 m) with five replies, having a total of 240
censuses. We found values indicating healthy and unhealthy reef fish communities,
which varied during the year. In general, shallow sites showed healthy values meanwhile
deep sites showed unhealthy ones. When a season analysis was made the values obtained
during rainy season were mainly of unhealthy conditions. No clear pattern was observed
between the distance to the coast and the health measure. Finally, comparing zones with
different fishing pressures, we observed healthy values for the shallow sites with low
fishing, but this pattern was not maintained for the deep sites. In spite more studies are
required, however the use of ABC curves showed potential for their use in fish
communities.
Poster Mini-Symposium 22: Coral Reef Associated Fisheries
22.873
Within Island Gradients in Human Disturbance Alter Demography Of Coral Reef Fishes
Mary DONOVAN* 1 , Sheila WALSH 2 , Stuart SANDIN 2 , Ben RUTTENBERG 1 , Scott
HAMILTON 1
1 Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, 2 Scripps
Institution of Oceanography, La Jolla, CA
Fishing down top trophic levels of coral reef fishes has potentially large implications for
ecosystem function and fisheries management. Previous studies looking at the demography of
coral reef fishes have generally focused on single species of fish with particular importance to
fisheries. In this study, we examined demographic patterns of five coral reef fish species from
different trophic levels collected from three regions around Kiritimati Island in the Line Islands.
The three regions vary in the level of human impact; fishing pressure tends to decrease with
increasing distance from the main population center on the island. We compared demographic
responses of fishes from these regions and assessed the individual effects of fishing pressure,
benthic habitat, and primary productivity (e.g., chlorophyll a). We employed standard
techniques using otolith ageing to describe the demography of these fishes. We found
significant differences in growth rates and longevity among regions and trophic levels that were
most likely explained by differences in predator communities. This study highlights the impacts
of anthropogenic effects, such as fishing, and its effects on multiple trophic levels, and that
these effects can vary over small spatial scales, such as within a single small atoll. In regions
with large impacts by humans, the removal of piscivores may reduce predation of lower trophic
levels which leads to increased growth rates and longevity compared to regions with less human
impact.
22.874
Indications Of Recruitment Enhancement in The Sea Urchin Tripneustes Gratilla Due To
Stock Restoration Efforts
Marie Antonette MEÑEZ* 1 , Davelyn PASTOR 1 , Helen Grace BANGI 2
1 University of the Philippines, Marine Science Institute, Diliman, Quezon City, Philippines,
2 Mariano Marcos State University, College of Aquatic Sciences and Applied Technology,
Currimao, Ilocos Norte, Philippines
Restocking of marine protected areas and grow-out culture of hatchery-reared Tripneustes
gratilla juveniles were used to enhance the recovery of depleted reef fishery stocks. Insights on
the impacts of these interventions were gained from field monitoring activities conducted in
four sites in Bolinao, Pangasinan and one site in Poro Point, La Union Philippines between
2004-2007. Areas were surveyed using standard belt transect method (100m X 2m X 3
transects) to determine densities and size frequency distributions. Temporal trends in the
incidence and abundance of recruits (1 individual m-2 was observed for the first time in 2004 since the collapse of the
fishery in 1992. The highest density was >4 individuals m-2in Lucero, Bolinao in January
2006. In Poro Pt., densities increased after initiation of grow-out culture activities in 2005 and
peaked at >1 individuals m-2 in 2007. In both sites juveniles comprised up to over 80% of the
sea urchins encountered in field surveys during October to February in 2004 to 2007. This
indicates high benthic recruitment success during the prevalence of the SW monsoon in June
through October. The positive correlation in the density of recruits and adults in the four sites
in Bolinao, and the high incidence of recruits in the grow-out area in Poro Pt. suggest that the
aggregation of adults enhanced benthic recruitment. The potential for a network of marine
protected areas and grow-out culture to enhance larval sinks and sources for T. gratilla are
examined in relation to simulations of larval dispersal given hydrographic conditions during
different times of the year and the distribution of suitable reef habitats along NW Luzon.
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