Coral reefs on the islands of Kaua'i, Moloka'i, Maui, Hawai'i and O'ahu were surveyed for the presence and impact of marine nonindigenous and cryptogenic species (NIS) using a rapid assessment method that standardized search effort for approximately 312 m2 at each site. A total of 41 sites were surveyed by three investigators for a total of approximately 120 hours search time on the five islands. Algae, invertebrate, and fish taxa were identified on site or returned to laboratory for identity confirmation. Only 26 NIS, comprised of three species of algae, 19 invertebrates, and four fishes were recorded from a total of 486 total taxa on the entire study, and 17 of the NIS occurred at only one or two sites. The most NIS that occurred at any site was six, and 21 of the sites had less than three. If the three species of fish that were introduced in the 1950s and known to occur throughout Hawai'i are excluded, over half the sites had less than two NIS.
The purpose of the present study was to determine the presence and impact of nonindigenous (introduced) marine species on Hawai'i's coral reefs.
NOAA Supplemental: :Entry_ID: Unknown: Sensor_Name: SCUBA, visual census; Sensor_Name: transect line; Project_Campaign: Hawaii Coral Reef Initiative; Originating_Center: Bishop Museum; Storage_Medium: MS Access; Online_size: 5941 Kbytes Resource Description: NODC Accession Number 0001419
ground condition
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Hawaii Biological SurveyBishop MuseumHawaii Coral Reef Initiative
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coral reef study
The methods used in biological sampling programs vary with the research questions being asked and require decisions pertaining to levels of effort directed toward two primary objectives. The first is to determine as completely as possible the total community species composition occurringat the sampling site. The second is to quantify the abundance or relative abundance of the various community components in an attempt to determine the numeric distribution of numbers of individuals or areal coverage of the various component species. These two objectives are somewhat opposing, especially where time is limited when sampling underwater. Most studies on coral reefs have focused on algal, coral, or fish assemblages and have utilized some variation of linear or belt transects, or, in the case of coral and algae, measurements with quadrats, either sampled once or repeatedly on permanently marked sections of reef surface. The power and efficacy of sampling coral coverage in Hawai'i have been reviewed by Brown et al. (in press). These approaches provide various levels of quantification and resolution that may enable time series analysis, but the area sampled must necessarily be small, and such studies sometimes also include "swim-arounds" on larger reef areas to detect species that are not encountered on the fixed transects or quadrats. The purpose of the present study was to determine the presence and impact of nonindigenous (introduced) marine species on Hawai'i's coral reefs. Anticipating that these species were likely to be low in abundance, our approach was focused on examining large areas and on as many habitats as could be done within the time frame of scuba dives in water of intermediate depths of 10-20 m up to three times per day. In order to facilitate a comparable search effort among islands and sites within islands, we developed a standardized method that could be replicated on every survey. This approach utilized a variation on the belt transect and timed search methods that was modified to provide both a standardized search area, estimates of probability of encounter and a sufficiently large search area to assure that most species occurring at the site had been encountered and noted. Where feasible the locations of surveyed sites were at or near sites established by the Hawai'i Coral Reef Assessment and Monitoring Program (CRAMP) in order to provide further information on areas that will be periodically resurveyed for coral and fish abundance (Brown et al. in press). Field Techniques After recording the position by GPS of the reef to be surveyed, a 50-m transect line was used to delineate a triangular area within which observations were made during the first 30 minutes of the survey. The starting point for the transect line was established haphazardly and the line was laid along the reef parallel to the shore for 25 m, then turned at a right angle for the remaining 25 m,with the resulting triangular area established by the line thus approximating 312 m2. Two observers (SLC and FK) swam in tandem along the line, noting and recording the first occurrence of all invertebrates, fishes and identifiable macroalgae occurring along a swath up to 2 m on either side of the transect within time periods of 5, 10, and 15 minutes from the start time of the transect. The next 15 minutes were spent recording organisms that occurred in the 312 m2 triangular area delineated by the legs of the transect line. Finally, 15 minutes were spent makingobservations outside of the triangle and recording all taxa not previously observed. In addition to the observations made by these two observers, on Kaua'i, Moloka'i, Maui, and Hawai'i a third diver (PAR) searched crevices and microhabitats throughout the triangular area, identifying small and cryptic organisms not observed by the first two divers on their roving searches. All organisms identifiable in the field were recorded on underwater paper, and samples of organisms were retained for identification in the laboratory where necessary. Identified organisms were entered on spreadsheets coded 1 to 3 according to the 5 minute period in which they were first encountered in the first 15 minutes, or 4 if they were first encounteredlater inside or outside of the triangle. In the event that the organism was recorded at different times by the different observers, the first encounter was assigned priority. Status of the species as nonindigenous, cryptogenic or native was assigned according to their designation in Carlton and Eldredge (in prep.) and the Checklist of the Marine Invertebrates of the Hawaiian Islands (http://www2.bishopmuseum.org/HBS/invert/list_home.htm). (Species of uncertain identity but suspected to be introduced were collected and returned to the laboratory for identification and/or verification by taxonomic experts.
Two original files provided:filename commentHCRI_Final_Report.pdf complete reportRelational_Database.mdb MS AccessThe tables in the relational database were extracted and saved as MS Excel (97-2000)and comma-separated version (CSV). Table names:OccurencesSpecies ListStation
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