This dataset contains observations from Phase II.
B. Bishop Museum Collections The Bishop Museum collections of aquatic insects, mollusks, other invertebrates, and fishes were reviewed for all estuarine and freshwater organisms historically collected from Pearl Harbor wetlands, springs, and fresh and estuarine portions of streams entering Pearl Harbor. For the mollusk and fish collections this involved searching the collection catalogs for specimens that were collected from Pearl Harbor and entering into a database species name, year of collection, and collectors names. The combined data from all sources were assembled into a relational database of Pearl Harbor freshwater and estuarine organisms.
C. Field Surveys- General Methods Sampling for Phase II of the Pearl Harbor Biodiversity Project began in October 1997 and ended in August 1998. Representative sampling stations were established in each major Pearl Harbor stream and wetland. Sampling locations were somewhat dependent upon the constraints of private property, water depth, sediment depth, and vegetation, but included a complete range of estuarine habitats. Riparian vegetation composition and stream substrate were evaluated at each sampling station. Habitat condition for native aquatic organisms was evaluated both within sampling stations and throughout the study area. Most sampling stations were generally at or just above sea level.
Insect Sampling
Aquatic insect sampling was conducted according to Polhemus (1995) and Englund et al. (1998). Collections of both immature and adult specimens were made with aerial sweep nets, aquatic dip nets, seines, and by taking benthic samples. Visual observations of aquatic insects were also conducted above the waterbody. In addition, the sampling of damselflies and dragonflies (Odonata) was emphasized as several of these are currently candidate threatened or endangered species. All insect specimens were stored in 75% ethanol and subsequently transported to the Bishop Museum Entomology Collection for curation and identification. Voucher specimens are currently housed in the Bishop Museum collections.
We also collected and identified the predominant terrestrial insects on vegetation immediately in the vicinity of riparian habitats, as some riparian insects were an important part of fish diet in the lower reaches of Pearl Harbor streams.
Benthic Sampling
Bottom communities in the soft-sediment areas of streams were sampled with a Wildco Petite Ponar@ 15.2 x 15.2 cm (6 x 6 in) weighted dredge. Three dredge samples were collected at each Pearl Harbor stream mouth and were usually taken from the Chevron petroleum pipeline bridge crossing areas. After collection of the dredge samples, sediments were rinsed out through a fine- meshed 1 x 1 mm (0.04 x 0.04 in) seive. The contents were preserved in 75% ethanol for later laboratory analysis.
Fish, Crustacean, and Mollusk Sampling
Seine netting was the main sampling technique used to assess introduced fish abundance. A fine- mesh, 5 m (16.4 ft) long seine was used to sample stream animals and assess species composition, and dip nets were also used to sample areas not accessible to seines. Experimental gill nets of varying sized mesh were also used in areas that were too deep to seine. Salinity was also recorded at least once for each stream location sampled, and, unless otherwise stated, salinities were taken at the surface. Because of poor water visibility throughout the Pearl Harbor estuaries, snorkeling was used only in the area of the concrete weir at Waikele Stream. In other areas, above-water observations for fish and invertebrates were occasionally possible, although species identification was generally assessed through capture of individuals. Electrofishing in conjunction with the Hawaii Division of Aquatic Resources was attempted but was not successful because most areas sampled during this study had detectable levels of salinity. Even the small amount of salinity at the Waiawa Springs complex (2 to 4 ppt) rendered electrofishing completely ineffective. Although some fish, crustacean, and mollusk species were identifiable in the field, many smaller specimens were immediately preserved in 75% ethanol and brought back to the Bishop Museum for further identification. The estuarine areas of Waikele, Waiawa, and Halawa Streams, and the Waiawa Springs outlet were accessed by kayak. Visual observations and salinity measurements of aquatic biota were also made while kayaking to the tidal flats. For this report, we used the scientificand common names of fishes published by the American Fisheries Society (American Fisheries Society 1991 ), crustaceans (American Fisheries Society 1989), and Nishida (1997) for insect names and biogeographic status. Many of the organisms discussed in this report do not have common names. For those species having a common name, a general common name (e.g., moth) is used, and after that the organism is referred to by its scientific name.
Fish Diet Analysis
A small sub-sample of native and introduced fish collected in the lower stream, wetland, and estuarine regions of Pearl Harbor were preserved in 75% ethanol after capture for later stomach content analysis. Fish stomach contents were identified to the lowest possible level, although in many cases identification to the species level of partially digested prey items and smaller crustaceans such as amphipods and ostracods was not possible. Total prey item numbers in each fish stomach were recorded. Head capsules were counted to assess prey item numbers if stomach contents were broken into pieces. The terrestrial or acquatic status was determined for each identifiable prey item found in fish stomachs.
Englund, R.A., 2002. The loss of native biodiversity and continuing nonindigenous species introductions in freshwater, esturine, and wetland communities of Pearl Harbor, Oahu, Hawaiian Islands. Estuaries. Vol. 25, No. 3. p. 418-430.
Files within each directory are:
./data/Access: PearlHarbor-97.mdb*
./data/Excel: Class_and_Order.csv* Class_and_Order.xls* PH_Complete_Taxon.csv* PH_Complete_Taxon.xls* all_fauna_id.csv* all_fauna_id.xls* guts_data.csv* guts_data.xls* station.csv* station.xls*
./data/reports: PearlFinal.pdf* estuaries_pearl_harbor.pdf