In combination with the cages, ropes were also deployed with algae attached (i.e. exposed to grazers) at 10m intervals along 150m shallow and deep transects at each site. Algae species were the same as those used in the growth assay cages and similarly weighed before and after deployment. Changes in weight over the period of deployment were combined with algae growth data from growth assays to calculate the herbivorous fish community grazing rate on each species of macroalgae.
To determine the grazing preferences and grazing rates of individual species of herbivorous fish, divers performed fish behavior observational surveys. Divers followed individuals of the families Scaridae (parrotfish, uhu) and Acanthuridae (surgeonfish, tangs, manini, kole, etc.) to record bite rates and type of substrate (different types of algae, coral, sand, etc.) consumed by fish during 3-5 minute timed swims. If fish behavior appeared to be altered by diver observation, observation of that fish was terminated and the data excluded from analysis. At least 10 observations were made for each of the most common species of herbivorous fishes as determined from DAR fish survey data.
To verify observational data, gut contents were analyzed from a small sample of representative Acanthurids speared at Kapalua Bay (a somewhat analogous reef to Kahekili that is not protected) and Scarids purchased at a fish market. Fish were dissected within hours of being caught or frozen immediately for later dissection with minimal enzymatic activity degrading gut contents. Contents were analyzed in the lab to algae functional group and compared to observation data.
(2) Examine the differential effects of urchin versus fish grazing on benthic community structure
In order to discern grazing rates of urchins on common macroalgae species on Maui reefs and to determine whether urchins and fish are functionally redundant grazers on the reef, urchin grazing experiments were conducted at the Maui Ocean Center in large flow-through tanks. Similarly to fish assays, algae were weighed before and after deployment to determine grazing over time. Each experiment had three controls to account for growth over deployment. Algae thalli were rubber-banded to a fishing weight at the bottom of each enclosure. Experiments included common fleshy algae at Kahekili: Acanthophora spicifera, Ulva fasciata, and Amansia glomerata, as well as Hypnea musciformis, a common invasive alga around Maui though not present at Kahekili. Choice experiments involved three species of algae in a given enclosure and lasted 24 hours.
In addition to explicit grazing experiments, we further examined the role of urchins and fish in situ. This work involved four caging treatments including 1) closed cage excluding fish and urchins, 2) closed cage including urchins only, 3) open-top cage including urchins and open to fish, and 4) open-top cage excluding urchins and open to fish. There were six replicates of these four cage treatments plus six control quadrats marked by two stakes. Cages were made of vinyl-coated chicken wire (1-in mesh) and measured 0.5 x 0.5 m. Cages were established on areas composed of algae and coral cover, with care taken to prevent injury to coral. Cages with urchins had one urchin per cage (similar to natural densities on the reef), collected from the site of the experiment and released back on to the reef after the completion of the experiment. Data were collected every two weeks for the first three months and every three months thereafter. The experiment ran for one year. Measurements included photoquads for composition analysis, height of algae, and benthic composition. Percent cover of benthic species and an algal index were calculated from these measurements. The algal index is the height of algae multiplied by the percent cover of the species.
(3) Determine if relationships exist between grazing intensity and benthic community composition around Maui Island
Through collaboration with DAR and NOAA CRED, data from CRAMP benthic cover and WHAP fish biomass data were collected for sites around Maui to compare grazing intensity at each site with benthic composition. Fish bite rate data (from Obj 1) was used in this analysis to compare grazing preference and intensity v. benthic cover. Fish biomass data at WHAP sites were combined with fish bite data collected at KHFMA and compared to benthic cover at CRAMP sites. Comparison of grazing intensity and benthic cover occurred at those locations where fish and benthic data are taken.
(4) Determine how nutrient enrichment may affect grazing susceptibility on different algal taxa
To identify whether herbivores preferentially consume algae with higher tissue nutrient levels, species of algae that were most highly favored by herbivores, Acanthophora spicifera and Ulva fasciata, were collected from a naturally high nutrient site (Waipulani) and divided into treatments to be grown in full sun in aquariums of high or low nutrient water over the following ten days. Water was collected from Olowalu, West Maui (low nutrient water) and was supplemented with .05 g / gallon crushed Osmocote pellets in seawater to increase water nutrients for high nutrient treatments. Water samples were taken daily to confirm elevated nutrient levels. High and low nutrient samples for Ulva and Acanthophora were deployed on the reef for up to 3 days as in the grazing assays in Objective 1. Urchin assays were conducted as in Objective 2.
Nutrient-enrichment grazing assays for fish and urchins were repeated using naturally enriched and unenriched algae samples to control for the potential of laboratory manipulation during enrichment / desaturation altering the outcome of grazing preferences. Samples were collected, weighed, and deployed on the reef within 24 hours of collection. High nutrient samples were collected at Waipulani. Low nutrient samples were collected at Olowalu (Acanthophora) and Puamana (Ulva).
INSTRUMENT TYPES: SCUBA, collection bags, cages, ropes
file: HCRI_finalreport_SMITH.pdf format: PDF-archive content: Final report to the Hawaii Coral Reef Initiative.
file: JenniferSmithHCRI2011.pdf format: PDF-archive content: A progress report to the Hawaii Coral Reef Initiative.
data/ holds data
subdirectories:
0-data/ This directory contains the original files as provided by the contributor
filename: Enrichment_fishurchins_100511_SMITH_HCRI_submitted.xlsx format: MS Office Excel 2007 content: metadata and data on fish, urchins, and algae by category of environment (enriched vs. unenriched)
filename: Fish_bite_datasheet_100511_SMITH_HCRI_submitted.xlsx format: MS Office Excel 2007 content: metadata and data on fish consumption (coral, turf, algae, etc).
filename: Fish_urchin_expt_100511_SMITH_HCRI_submitted.xlsx format: MS Office Excel 2007 content: metadata and data on fish and urchin species, sizes, bites per minute by food type (turf, coral, algae, etc).
filename: Grazing_assays_100511_SMITH_HCRI_submitted.xlsx format: MS Office Excel 2007 content: metadata and data on grazing assays
1-data/ This directory contains files generated by NODC. These files are comma-separated version (CSV) text exports of the unique sheets of the original MS Excel files in 0-data/.
There is one file for each sheet within each original MS Excel file. The file name is the original MS Excel filename root appended with the individual sheet name.
file: Enrichment_fishurchins_100511_SMITH_HCRI_ALL_FISH.csv content: Nutrient Enrichment Experiment, roof enriched fish at KHFMA 1) Percent Tissue Removed as a function of depth (shallow: 5-8 ft, deep: 16-18 ft), algae (Acanthaphora, Ulva) and category (naturally unenriched, naturally enriched, unenriched, 0.2g or 0.4g enriched). 2) G Tissue Removed as function of same variables
file: Enrichment_fishurchins_100511_SMITH_HCRI_Natural_fish.csv content: Specifics for fish naturally enriched at KHFMA. Specimens from Waipulani, Puamana, and Olowalu. Columns clarified in discussion of Methods above.
file: Enrichment_fishurchins_100511_SMITH_HCRI_Roof_fish.csv content: Specifics for roof enriched fish at KHFMA as a function of depth, algal type, enrichment type
file: Enrichment_fishurchins_100511_SMITH_HCRI_Roof_urchins_Expt_1.csv content: Nutrient Enrichment Experiment, part 1 of experiment, roof enriched, urchins at the Maui Ocean Center (MOC), as a function similar to fish experiments. See Methodology for an explanation.
file: Enrichment_fishurchins_100511_SMITH_HCRI_Roof_urchins_Expt_2.csv content: Nutrient Enrichment Experiment, part 2 of experiment, roof enriched, urchins at the Maui Ocean Center (MOC), as a function similar to fish experiments. See Methodology for an explanation.
file: Enrichment_fishurchins_100511_SMITH_HCRI_submitted_metadata.csv content: metadata associated with the project
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_avg_bites_min_g.csv content: independent variables: date, time, depth, fish family, species, common name, species code dependent variables: acquire average rate of consumption of algae column: sizecm content: size of fish (cm) column: Bio(g)Record content: weight in grams column: TL to SL_FL factor content: size ratio factor column: A content: calculation parameter column: B content: calculation parameter column: sex content: m: male f: female column: min content: how many minutes recored column: <type> bites/min content: how many bites of turf occurred per minute column: <type> /min/g content: estimated grams of turf in each bite Note: <type> can be turf, CCA, Halymenia, Triclecarpa, Asparagopsis, Turbinaria, Tolypiocladia, other macroalgae, Sand, coral, other
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_bites_per_minute_per_g_herb.csv content: independent variable: species, sex, and size of herbivore fish and duration (seconds or minutes) of observation dependent variables: bites per minute of each <type> as above
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_bites_per_minute_pivot.csv content: as previous file yet for pivot fish
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_CALC_g_per_min.csv content: Bite rates per minute with bite size (from bite size spreadsheet 842411).
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_g_alg_min_g_fish.csv content: INCOMPLETE, please ignore this file
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_metadata.csv content: metadata associated with the project
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_Original_data.csv content: Fish bite observations from Kahekili area independent variables: site, GPS (no data), date, time, diver, species, sex, size, average depth (feet), End time (length of observation, as minutes:seconds and total seconds) dependent variables: <type> of what was bitten
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_Sheet1.csv content: please ignore, a working table
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_sp.csv content: fish species common name, family, and general species
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_total_bite_min_m2_C.csv content: a comparison with Division of Aquatic Resources fish bite data made in 2008-2009 for select species at Canoe Beach and also DAR sites on Maui and Lanai
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_total_bite_min_m2_K.csv content: same as above yet for Kahekili
file: Fish_bite_datasheet_100511_SMITH_HCRI_submitted_total_bite_min_m2_LL.csv content: same as above yet for Lanai Lighthouse
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_algal_index.csv content: an algal index is defined for open areas versus KHFMA for cases of <plot types>: urchins only, fish plus urchins, fish only, no herbivores.
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_code_key.csv content: code names for select species as well as nicknames
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_Heights_FG.csv content: measurements of submitted heights (mm*10) of bites from urchins for select species and <plot types>
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_height_with_percent_cover.csv content: calculated percent cover of substrate versus <plot types>
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_metadata.csv content: metadata associated with the project
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_Primer.csv content: Pictures used as basis for estimating height of bite (mm*10) as a function of substrate and <plot type>
file: Fish_urchin_expt_100511_SMITH_HCRI_submitted_Turf_and_As.csv content: heights of bites (mm*10) as a function of substrate and <plot type>
file: Grazing_assays_100511_SMITH_HCRI_submitted_4_sp_grazing.csv content: laboratory tests at the Maui Ocean Center Species, sampling period, weight (grams), amount consumed (grams)
file: Grazing_assays_100511_SMITH_HCRI_submitted_grazed_ggday.csv content: Grazing rates (rope growth grams, grams/day-growth, grams/day-grazed ) for select species at Kahekili, Canoe Beach and Lanai
file: Grazing_assays_100511_SMITH_HCRI_submitted_metadata.csv content: general metadata for project
file: Grazing_assays_100511_SMITH_HCRI_submitted_Summer_2010_grazing_assays.csv content: Kahekili, Lanai, and Canoe Beach grazing assays as function of sampling period, depth, treatment and select species, initial and final wet weight (grams), initial and final dry weight (grams).