Geology topics

J.D. Parrish

Publications and source records attributed to J.D. Parrish.

6 recordsLinked to original sources

USGS2006

Ecological characteristics of coral patch reefs at Midway Atoll, Northwestern Hawaiian Islands

Ecological aspects of coral patch reefs were studied from 1981 to 1985 in Welles Harbor, Midway Atoll. Water temperatures varied from 17??C in February to 28??C in August. Sizes of reefs studied were described by mean area (59 m2), mean volume (52 m3), vertical relief (<1 m), and inter-reef isolation (100 m). Considerable temporal change in reef size occurred due to large winter swells shifting bottom sand. Six common species accounted for 70% of all individual fish visually censused over 4 years. Overall fish assemblage composition ranged from 11 to 46 fish/10 m2, from 3 to 14 species. Numerical abundance and species richness for all fish (pooled) strongly correlated with physical reef substrate characteristics of area, volume, and vertical relief during summer. Species diversity (H') was not correlated with the substrate variables, suggesting similarity in the structure of fish communities among different sizes of patch reefs. Daily surveillance for presence of large transient taxa suggested that visits by sharks, large jacks, monk seals, sea turtles, and dolphins were infrequent. Density estimates were made for all conspicuous invertebrate megafauna during initial and final assessments. Six common taxa provided 90% of these counts; nearly half were sea urchins. Percent cover also was recorded for coral and algal species on the patch reefs. Cover by live coral was low (about 7%) and dominated by a few species. Mean algal cover ranged from 32 to 77%. Such information on ecological characteristics of reefs may aid in understanding complex ecological processes and provides an earlier reference for current ecosystem studies.

Atoll Research Bulletin↗

USGS2005

Spatial relationships between an introduced snapper and native goatfishes on Hawaiian reefs

It has been suggested that the introduced blueline snapper (Lutjanus kasmira, Family: Lutjanidae) may adversely affect populations of native fishery species in Hawai'i through competition for spatial or dietary resources, or through predation on young fish. We studied the habitat use patterns of L. kasmira and several native reef fish species using direct observation by SCUBA divers. Habitat use patterns of the yellowtail goatfish (Mulloidichthys vanicolensis, Family: Mullidae) were most similar to those of L. kasmira. Both species were primarily found low in the water column and were closely associated with areas of vertical relief. Individual M. vanicolensis were found higher in the water column when L. kasmirawere present, but L. kasmira were not similarly affected by M. vanicolensis. This finding suggests asymmetrical competition for shelter, in which the dominant L. kasmira displaces M. vanicolensis farther into the water column. This displacement from the protection of the reef could increase the vulnerability of M. vanicolensisto predators and fishers. ?? Springer 2005.

Biological Invasions↗

USGS2005

Resilience of predators to fishing pressure on coral patch reefs

Numbers and biomass of piscivorous fish and their predation on other fish may often be high in undisturbed coral reef communities. The effects of such predation have sometimes been studied by removal of piscivores (either experimentally or by fishermen). Such perturbations have usually involved removal of large, highly vulnerable, mobile piscivores that are often actively sought in fisheries. The effects of fishing on smaller, demersal, semi-resident piscivores have been little studied. We studied such effects on the fish communities of patch reefs at Midway atoll by experimentally removing major resident, demersal, piscivorous fishes. First, four control reefs and four experimental reefs were selected, their dimensions and habitats mapped, and their visible fish communities censused repeatedly over 1 year. Census of all control and experimental reefs was continued for the following 39 months, during which known piscivores were collected repeatedly by hand spearing. Records were kept of catch and effort to calculate CPUE as an index of predator density. Spearfishing on the experimental reefs removed 2504 piscivorous fish from 12 families and 43 taxa (mostly species). The species richness of the catch did not show an overall change over the duration of the experiment. Spearman rank correlation analysis showed some unexpected positive correlations for density in numbers and biomass of major fished piscivorous groups (especially lizardfish) over the experiment. Only two relatively minor fished piscivorous taxa declined in abundance over the experiment, while the overall abundance of piscivores increased. Visual censuses of fish on the experimental reefs also failed to show reduction of total piscivores over the full experimental period. No significant trend in the abundance of lizardfish censused over the full period was apparent on any of the control reefs. The high resilience of piscivores on these experimental reefs to relatively intense fishing pressure could result from their protracted recruitment seasons, high immigration rates, cryptic habits, or naturally high abundances. A major factor was the high immigration rates of lizardfish, replacing lizardfish and other less mobile piscivores removed from the reefs by spearing. On the fished reefs, the removed lizardfish population replaced itself >20 times during the experiment; other piscivorous taxa replaced themselves only 5 times.

Journal of Experimental Marine Biology and Ecology↗

USGS2003

Importance of benthic prey for fishes in coral reef-associated sediments

The importance of open, sandy substrate adjacent to coral reefs as habitat and a food source for fishes has been little studied in most shallow tropical waters in the Pacific, including Hawai'i. In this study, in Hanalei Bay, Hiwai'i, we identified and quantified the major invertebrate fauna (larger than 0.5 mm) in the well-characterized sands adjoining the shallow fringing reefs. Concurrently, we identified the fish species that seemed to make substantial use of these sand habitats, estimated their density there, sampled their gut contents to examine trophic links with the sand habitat, and made other observations and collections to determine the times, locations, and types of activity there. A variety of (mostly small) polychaeres were dominant in the sediments at most sampling stations, along with many small crustaceans (e.g., amphipods, isopods, ostracods, and small shrimps) and fair numbers of mollusks (especially bivalves) and small echinoids. Fish guts examined contained ???77% of the total number of benthic taxa collected, including nearly all those just listed. However, fish consumption was selective, and the larger shrimps, crabs, and small cryptic fishes were dominant in the diets of most of the numerous predator taxa. Diets of benthic-feeding fishes showed relatively low specific overlap. The fish fauna in this area included substrate-indifferent pelagics, species with various degrees of reef relatedness, reef-restricted species, and (at the other extreme) permanent cryptic sand dwellers. Data on occurrence and movements of fishes indicated that a band of sandy substrate several tens of meters wide next to the reef was an active area for fishes, and activity was considerably different at different times of day and for fish of different ages. These results imply an important trophic role for the benthos in these near-reef habitats in support of reef-associated fishes.

Pacific Science↗

USGS2002

Estuaries as nurseries for the jacks Caranx ignobilis and Caranx melampygus (Carangidae) in Hawaii

Estuaries provide juvenile nursery habitat for many species of fish that inhabit marine environments as adults. In Hawaii, some juvenile Caranx ignobilis and Caranx melampygus occupy estuaries opportunistically before moving to nearshore ocean habitats. This study examined the extent and nature of estuarine habitat available in the lower Hanalei River of Kauai, the relative abundance and distribution of jacks in the estuary, and their diets. Salinity measurements indicated that the upstream extent of saltwater ranged from the mouth to nearly 5 km upriver and was strongly influenced by the variable river discharge. Juvenile jacks between 80 and 310 mm FL were observed on underwater transects over the full range of mixohaline conditions. Hand-operated seine collections produced overall catch rates of ???0.64 fish/haul for each of these species. The two jacks ate much the same spectrum of food items. C. ignobilis was somewhat more piscivorous than C. melampygus, as determined by measures of frequency of predation and number and bulk of prey. Data for length at age, incorporating daily otolith increment counts from these estuarine juveniles and previous counts from non-estuarine specimens, were fitted to a lifetime von Bertalanffy growth model. The results greatly extended the age range of the model and suggested that growth rates were not much different between estuarine and non-estuarine fish. ?? 2002 Elsevier Science Ltd. All rights reserved.

Estuarine, Coastal and Shelf Science↗

USGS1994

Reproductive and trophic ecology of the soldierfish Myripristis amaena in tropical fisheries

Squirrelfish of the genus Myripristis are valued in small-scale fisheries throughout much of the tropics. The life history and species biology of most of these soldierfishes is poorly known. For the brick soldierfish, M. amaena, in Hawaii and Johnston Atoll, we found that sexual maturity for both sexes was reached between 145 and 160 mm standard length at about six years of age - a large fraction of the apparent maximum size and lifespan. Fecundity was relatively low and increased as the fifth power of body weight. Spawning peaked from about early April to early May, and a secondary peak occurred in September. Myripristis amaena is a nocturnal predator, feeding mostly on meroplankton, especially brachyuran crab megalops, hermit crab larvae, and shrimps, but also taking a variety of benthic prey. In pristine fish communities, holocentrids were abundant, quantitatively important (often dominant) reef predators and prey. Myripristis amaena (and probably other common and important soldierfish) seems to be relatively long lived (at least 14 years), slow growing, and late maturing. The populations suffer considerable natural predation and depend mainly on the largest and oldest fish for reproduction. Heavy, unregulated fishing of these soldierfish, especially at prereproductive size, may severely reduce populations.

Fishery Bulletin↗