Kaneohe Bay Research

Regeneration functions and microbial ecology of coral reefs

DiSalvo, Louis H — Mon, 01 May 1905 00:00:00 GMT

Rapid rates of production and consumption on coral reefs have been indirectly measured by several investigators who suggested the existence of rapid regeneration rates in these ecosystems. During 15 months in 1967-68 I attempted to characterize mechanisms and rates of regenerative functioning in coral reefs at Kaneohe Bay, Oahu, Hawaii and Eniwetok Atoll. Marshall Islands. Emphasis was placed on the study of bacteria and other microorganisms based on their typically important regenerative roles in other ecosystems. Complex internal spaces in reef formations and non-living porous coral skeletons appeared to be major sites of regenerative processing. Dead coral heads were obtained from several reef stations and returned to the laboratory for study of internally contained regenerative sediments. Sediments were characterized by chemical and biological assays, and results were compared between local stations as well as between the two major study regions. Additional measurements were made on selected fragments of reef regenerative mass (dead coral). Eniwetok Atoll regenerative sediments contained less than 1% acid-soluble residues, while similarly collected sediments from Kaneohe Bay contained about 24% insoluble (terrigenous) residues. Station averages for total sediment organic matter by ashing ranged from 6 to 12%, and Kjeldhal nitrogen values ranged from 0.2 to 0.7%. Significant amounts of soluble phosphorus and amino nitrogen were released from the dead head spaces during sediment recovery. Regenerative sediments and adjacent skeletal substrates were heavily populated by bacteria, diatoms, protozoa and meiofauna. Bacterial plate counts gave average values of 10 8 - 10 9 colonies per gram sediment. Significant numbers of bacteria were chitin or agar digesting types. Visual counts of diatoms gave values as high as 10 6 cells per gram dry sediment, and were directly proportional to chlorophyll "a" content of the sediments. Bottle respirometry showed consumption of 0.06 to 0.50 mg 02 per g dry sediment per hour. Characteristic mean values obtained for each station appeared to be directly related to the wave and current energy at each station. Antibiotics significantly reduced sediment respiration. Respirometry of algal-encrusted dead coral fragments showed rapid rates of production (P) and consumption (R). Antibiotic treatment of these fragments interfered with their Rand P in a coupled manner. Respirometry of entire dead heads showed that sediment respiration accounted for about 10% of the total respiration in each head. Bacteria were actively removed from water circulated over living and dead coral heads in a laboratory reef simulation. Some infaunal animals apparently digested bacteria that were removed from the water. Observations on infauna of the regenerative system indicated an active role in sediment production and processing, and in maintenance of internal spaces. The infauna apparently acted in symbiosis with the microorganisms to promote rapid organic breakdown processes. Total organic matter, Kjeldahl nitrogen, terrigenous derivatives, and pheophytin showed highest mean levels in sediments from Kaneohe Bay nearshore heads, whereas bacterial counts, diatom counts, and sediment metabolism were highest in sediments from offshore heads. These comparative differences were indications of stressed regenerative function in nearshore reefs, possibly due to land-derived inputs. Parameters measured for outer Kaneohe Bay were strikingly similar to various measurements at Eniwetok, suggesting that regenerative function was similar in geographically separated reefs. Some simplified energy diagrams for simulation suggest how animals and microorganisms are coupled to perform effective mineral recycling and structural renewal of reefs.

Removal and repopulation of the fishes on an isolated patch coral reef in Kaneohe Bay, Oahu, Hawaii

Wass, Richard Charles — Thu, 01 Jun 1967 00:00:00 GMT

The relation of temperature to calcification in Montepora verrucosa

Cox, Walter W — Sun, 01 Aug 1971 00:00:00 GMT

Reef-building or hermatypic corals are limited in their geographical distribution to the warmer waters of tropical oceans. Significant coral growth occurs only in water ranging from 180 C to 330 C, and massive reefs form only at temperatures toward the upper end of this temperature range (Wells, 1957). The coral skeleton is composed almost entirely of calcium carbonate (CaC03) with the crystalline structure of aragonite; calcite is completely absent. H. Lowenstam (1954) has suggested that the failure of corals to produce any calcite may be the factor influencing the smaller number of scleractinian species in cooler water. Organisms that can produce both aragonite and calcite tend to produce calcite during colder seasons and aragonite during warmer seasons. Thus, by their nature of calcification, corals may physiologically limit their geographical distribution. Physiological study of corals began in the early nineteenth century. Towards the latter part of the century, some work with growth rates of reef corals was started by Alexander Agassiz (1890). Similar studies have since been made by others (Abe, 1940; Boschma, 1936; Edmondson, 1929; Kawaguti, 1941; Ma, 1937; Mayor, 1924; Motoda, 1940; Stephenson and Stephenson, 1933; Tamura and Hada, 1932; and Vaughan, 1919). All of these stud ies involved the technique of allowing the coral to grow for long periods, days to years, in its natural environment, with size and weight measurements being taken at periodic intervals. However, more recent attempts to estimate growth rates have involved chemical methods of measuring the incorporation of calcium into the skeleton under controlled laboratory conditions (Kawaguti and Sakumoto, 1948; Coreau, 1959; and Goreau and Goreau, 1959, 1960a, 1960b). The present study employed a procedure involving the incorporation of radioactive calcium-45 into the coral skeleton to determine the optimum temperature for calcium deposition in Montipora verrucosa, a common Indo-Pacific hermatypic sc leractinian. In contrast to previous studies, short periods of one-half to six hours were used. These shorter periods were used in order to reduce adverse environmental laboratory conditions.

The Effects of ultraviolet radiation on skeletal growth and bleaching in four species of Hawaiian corals

Goodman, Gwen Davies — Wed, 01 May 1991 00:00:00 GMT

Coral bleaching has been attributed to many factors, including increased exposure to ultraviolet radiation (UV). The effects of partial and full spectrum UV on coral skeletal growth and bleaching were investigated. Responses were species-specific and depthdependent. Montipora verrucosa, Pocillopora damicornis, and P. danai collected from 1 m maintained or increased their calcification rates when exposed to partial UV or shielded from UV. M. verrucosa collected from 1.5 mexhibited bleaching via zooxanthella loss regardless of the UV treatment, probably because of reduced salinity and water temperature. M. verrucosa collected from 8.5 m bleached only when exposed to increased intensities of PAR, while Porites compressa collected from 8.5 m bleached only when exposed to increases in both PAR and UV. All bleaching resulted from loss of zooxanthellae rather than loss of pigment from zooxanthellae. Lower surface augmentation of color via zooxanthella increases often occurred with a corresponding decrease in upper surface zooxanthella density.

Interactions between trophic levels on coral reefs: Scleractinian corals and corallivorous butterflyfishes in Hawaii

Cox, Evelyn Fenton — Sun, 01 Dec 1991 00:00:00 GMT

Resource use by coral feeding butterflyfishes (Family Chaetotondidae) was studied at 6 geographic sites in the Hawaiian Islands. There was little diet overlap between the specialist species, Chaetodon unimaculatus and the generalist species, Chaetodon multicinctus, C. ornatissimus, and C. trifasciatus. Although there was high diet overlap between the generalist species, C. multicinctus showed a strong feeding preference for the coral Pocillopora meandrina. Chaetodon ornatissimus fed on corals roughly in proportion to their abundance, and C. trifasciatus, contrary to laboratory feeding preferences for pocilloporids and montiporids, fed on Porites spp. in the field. The specialist, C. unimaculatus, preferred Montipora spp. at all sites, and there was a trend towards a relationship between C. unimaculatus densities and coral cover of Montipora spp. There was no correlation between overall butterflyfish densities and coral cover at these sites. Butterflyfishes used non-overlapping feeding ranges intra-specifically, but showed high inter-specific overlap. Chaetodon multicinctus, the smallest bodied species, used the smallest areas and showed the most aggressive interactions against conspecifics and other butterflyfishes. The effects of grazing by butterflyfishes on coral was investigated with the Hawaiian coral Montipora verrucosa. M. verrucosa colonies, protected from the butterflyfishes with wide mesh cages, were compared to their clonemates exposed to predation. Although reproductive output was highly variable among clones, gamete weight per unit surface area of grazed clonemates was signficantly greater than their ungrazed clonemate. Ramets protected from butterflyfishes, however, had twice the linear growth as grazed ramets. These results corroborate the predictions of Williams (1975) Strawberry-Coral Model for the allocation of resources to reproduction in clonal organisms. Photosynthetic and respiratory rates were measured in a laboratory respirometry setup. Respiration rates and maximum photosynthetic capacity were the same for grazed and ungrazed clonemates. Parameters for light saturation curves for photosynthesis for clonemates were not significantly different, suggesting that energy available from the symbiotic zooxanthallae in protected clonemates was used to fuel rapid growth and in grazed clonemates to repair tissues and increase sexual reproduction. Thesis (Ph. D.)--University of New Mexico, 1991.; Includes bibliographical references (leaves [102]-123).

Factors affecting calcification processes in the hermatypic corals Pocillopora damicornis and Porites compressa

Clausen, Conrad D — Thu, 01 Jun 1972 00:00:00 GMT

Sessile Invertebrate Colonization of a Coral Patch Reef: A Study of Two Reefs in Kaneohe Bay, Hawaii

Lewis, Clark R — Fri, 01 Aug 1980 00:00:00 GMT

Marine invertebrate colonization for a complete annual cycle was examined on two coral patch reefs in Kaneohe Bay, Oahu, Hawaii. Polyvinyl chloride panels provided the substratum for settlement and their placement on the reefs was along windward to leeward (upstream to downstream) transects. Counts of individual organisms and area covered by colonies provided data for site by site and inter-reef comparisons of temporal and spatial colonization trends. Over 80% of the total invertebrate settlements could be ascribed to five taxonomic groups: oysters, barnacles, serpulid worms, bryozoans, and tunicates. The patterns of colonization exhibited by these five groups are analyzed and discussed in detail. The greatest numbers of new settlements consistently occurred at the shallow windward site of each reef, whereas the least amount of colonization took place in the middle of the study reefs. These colonization phenomena are discussed with respect to the influence of various physical and biological factors. Five months into the study, all of the fishes were removed from the smaller of the two patch reefs, providing at least temporarily, a means of examining the effects of fish on invertebrate colonization. Visual transects were used prior to and after fish removal to assess the resident fish population. Due to the rapid recolonization of the reef, particularly by dominant herbivores, major effects on invertebrate colonization patterns were not detected.

The Effects of Grazing by Parrotfishes (Family Scaridae) on Selected Shallow Hawaiian Marine Communities

Brock, Richard Eugene — Thu, 01 Jun 1905 00:00:00 GMT

This study has been conducted to: (1) assess the quantitative effects that rasping parrotfishes in a coral reef ecosystem have on the structure of benthic communities; (2) describe the standing crop of parrotfishes and (3) examine scarid recolonization patterns on a fish depopulated patch reef. Field studies were conducted at both Johnston Atoll and Kaneohe Bay, Oahu, Hawaii from 1975 through 1977. These studies suggest that there are two principal groups of Hawaiian parrotfishes. i.e., those with heavy dentition (Scarus perspicillatus, S. sordidus and S. taeniurus) that consume large quantities of calcium carbonate and probably utilize endolithic resources and those possessing relatively lightweight dentition (Scarus dubius and Calotomus sandvicensis) that appear to feed primarily on epilithic organisms. The latter species are not particularly abundant possibly due to competitive interactions with other herbivorous fishes (e. g., acanthurids) on Hawaiian reefs. Using an acid dissolution technique of extraction, the cryptobiota are estimated to range from 10 to 1400 g/m2 (dry weight) and average about 50 g/m2 in most Hawaiian reef systems. This potentially large food resource is systematically harvested by few other large reef species besides some parrotfishes and sea urchins. Laboratory experiments conducted at the Hawaii Institute of Marine Biology in Kaneohe Bay using a flow-through seawater system suggests that parrotfish (Scarus taeniurus) at low density cause benthic community structure to proceed to macroalgal dominance. At intermediate density, (0.6 to 1. 5 parrotfish/m2 or 9 to 17 g wet weight/m2 ) a diverse, high biomass community (to 400 g/m2 dry weight) develops which may be enhanced by the presence of refuges. At Scarus densities greater than 1. 9 fish (20 g wet weight per m2 ) and in the absence of refuges, a benthic community of low diversity and biomass (3 to 8 g/m2, dry weight) develops. Under high grazing pressure coralline algae are competitively superior as manifested through greater coverage. Recruitment and growth of corals in the experimental situation correlates positively with increased grazing pressure and the presence of refuges (P < 0.01). These data suggest that parrotfishes may be important to the maintenance of the overall structure of coral reefs. thus acting as keystone species to other components of the benthic community. Parrotfish densities for optimum benthic community development in the laboratory are similar to those observed in some field situations (Kaneohe Bay, Oahu--1.1 fish or 10.8 g/m2 ), and maximal growth of juveniles occurs at such densities. Field experiments conducted at Johnston Atoll suggests that at normal field densities, parrotfishes may appreciably alter the benthic community structure in two dimensional (planar) systems. The addition of a third dimension (substratum depth) alleviates this negative impact. Coralline substratum samples exposed to average field grazing pressure tend to harbor a more diverse cryptofaunal community than is present in substrata protected from grazers. The presence of a third dimension appears to give the epilithic and cryptobiotic components the protection from grazers necessary for survival. Depopulation and recolonization studies conducted on an isolated Hawaiian patch reef suggests that the MacArthur-Wilson theory of island biogeography models the observed fish recolonization. The calculated wet biomass of fishes prior to depopulation was about 930 kg/ha which is in the range of other published studies. Fish community structure was dominated by planktivores (55% by weight) followed by carnivores (32%), herbivores (12%) and omnivores (2%). The large standing crop of planktivores was related to abundant plankton probably caused by local nutrient enrichment. Recolonization studies demonstrate that parrotfishes are one of the most successful groups to recolonize, suggesting that they are opportunistic in their habitat selection. A comparison of these data to those from the same reef 11 years earlier indicates that the structure of this community has been stable and has persisted in spite of local environmental change. Thesis (Ph. D.)--University of Washington, 1979. Bibliography: leaves [114]-126.