Gerald J. Bakus

Chemical ecology of marine organisms: An overview

An overview of marine chemical ecology is presented. Emphasis is placed on antipredation, invertebrate-toxic host relationships, antifouling, competition for space, species dominance, and the chemistry of ecological interactions.

Toxicity in Sponges and Holothurians: A Geographic Pattern

Toxicity in sponges and holothurians is inversely related to latitude and may reach 100 percent for holothurians in high-diversity coral reefs. Evidence from approximately 700 experiments and from underwater observations suggests that predation by fish has resulted in natural selection for noxious and toxic chemical compounds in species within these taxa.

Toxicity in Holothurians: A Geographical Pattern

Experiments on the toxicity of holothurians to fishes were conducted at Cocos Island (eastern Pacific), in Mexico, California, and Washington. Six of seven species of holothurians tested at Cocos Island are toxic to fishes. Five species in Mexico are toxic, one of two species in California is mildly toxic, and three of twelve species in Washington are mildly toxic to fishes. Feeding experiments confirm laboratory tests on toxicity. A summary of information is presented on the current status of our knowledge of toxicity in holothurians. The evidence supports the hypothesis that toxicity in tropical holothurians probably has evolved in part as a chemical defense mechanism against predation by fishes. THE PURPOSE of this investigation was to evaluate the hypothesis that toxicity in holothurians is inversely related with latitude and that this phenomenon is in part a reflection of fish predation, which differs in intensity with latitude and habitat (Bakus 1968, 1969). Studies were conducted at the Instituto Technologico de Monterrey, Escuela de Ciencias Maritimas y Technologia de Alimentos, Bahia de Bacochibampo, Guaymas, Sonora, Mexico (28? N), 30 December 1968 to 1 January 1969 and 2-4 April 1969; the University of Southern California Santa Catalina Marine Biological Laboratory (330 N) from 4 May to 11 May 1970; the Allan Hancock Foundation, University of Southern California, during 1969 and 1970; Cocos Island, eastern Pacific (6? N), from 29 March to 8 April 1972 and the University of Washington Friday Harbor Laboratories (48? N) from 24 July to 16 August 1972. MATERIALS AND METHODS Marine fishes and holothurians were collected by skindiving and with SCUBA, using the narcotizer quinaldine, dip-nets, and diving bags. They were maintained in aquaria. Tests were conducted to determine which holothurians are toxic to fishes and to obtain a rough approximation of the level of toxicity. Techniques used to study holothurians generally follow those of Bakus (1968) except where noted. Briefly, pieces of the animals are weighed (2 g) then placed in a beaker. A solvent (usually 95% ethanol) is added to the beaker and the solution is evaporated by boiling for 20 minutes. The extracted residue is dissolved in 100 ml of fresh seawater, distilled water, or tapwater in a fingerbowl. A fish is placed in the fingerbowl, and the time at which it dies is recorded. Experiments were terminated when fish showed consistently normal behavior or had died. Violent escape behavior, paralysis, and loss of equilibrium indicated the presence of a toxin. A strongly toxic holothurian is defined as causing death in fishes within 15 minutes (often < 10 minutes); a weakly toxic holothurian causes death in fishes from 20 to 45 minutes. Temperatures under which experiments were conducted were at or near the ambient for the site of capture, unless otherwise indicated, in order to simulate natural responses to toxins by fishes. Control experiments were conducted simultaneously with every test experiment. They consisted of placing fishes in the same volume of clean seawater or freshwater as that used in the experiments. OBSERVATIONS ON THE BIOLOGY

Sedimentation and benthic invertebrates of Fanning Island, central Pacific☆

Abstract Experiments conducted at Fanning Island (atoll), central Pacific, during late June through late August of 1963 indicated that many sponges and ascidians are affected adversely by sediment deposition. This occurs by burial and by clogging of canals and chambers. The rate of deposition of small and medium-sized silt bioclastics at the edge of the lagoon for the first two days was about 1 mm/day. This rate (apparent) decreased with time so that after 15–35 days there was an average deposition of about 3 mm of sediment.

Decision making: With applications for environmental management

The two major processes of decision making, behavioral interactions and decision analysis, are discussed. Comparisons are made between the Delphi and NGT methods of behavioral interaction. Three different types of decision analysis are compared, including the Goals Achievement Matrix, Concordance Analysis, and the Simple Multi-Attribute Rating Technique. Decision making problems characteristic of environmental studies are reviewed. A method of decision making that combines the best qualities of other methods is suggested. The overall purpose of this paper is to make the technical knowledge of decision making useful to environmentalists, businessmen, citizens, and politicians, and to improve the process of policy making in environmental studies.

A modified allomone collecting apparatus

A modified allomone collecting apparatus was designed that could be used under water with a scuba tank. This apparatus provides a simple method of obtaining naturally secreted chemicals from benthic marine organisms at scuba depths, for the first time without the necessity of using a bilge pump. Organic material from Sep-paks in the allomone collector confirmed the release of secondary metabolites from a soft coral into the surrounding water.

The selection and management of coral reef preserves

Abstract The value of coral reefs has been established on the basis of their high diversity, valuable resources, and recreational and aesthetic amenities. Coral reef ecosystems are being destroyed by a plethora of events including coastal development, overfishing, and the exploitation of biological products. The selection of coral reef preserves can be made on the basis of location, size, optimal yield and linkage. Areas to be considered can be assessed by biological, economic and sociological research. The economic value of each preserve can be estimated. User conflicts can be identified and a series of priorities can be established. Alternative sites can be compared using a powerful decisionmaking process (multi-attribute utility analysis). The selected preserves can be treated as a multiple-use resource and can be divided into user habitats for total preservation, exploitation, recreation, and research and education. Permits and fees, research, monitoring, enforcement, and public information and awareness play an important role in the success of the establishment of coral reef preserves.

A comparison of some population density sampling techniques for biodiversity, conservation, and environmental impact studies

Twelve terrestrial and marine studies were conducted at various sites in Malaysia, Brazil, and the United States between April 1999 and February 2004. These data were analyzed using five density estimate techniques for stationary (non-motile) organisms including Stratified Random Sampling, Point-Center Quarter, Third Nearest Object, Weinberg, and Strong. The Strong method gave the most accurate density estimates of stationary animals and plants. Stratified Random Sampling ranked second best and the Third Nearest Object the third best. Belt or strip transects may be preferable but can be restrictive in some situations because of logistics and associated time constraints. Straight line measurements on reefs were 3–27% more accurate than reef slack line and reef contour measurements. Most study areas measured with the standardized Morisita index of dispersion were moderately aggregated. Results from the Third Nearest Object and Point-Center Quarter techniques indicate that the addition of more data to establish a density correction factor does not necessarily give more accurate estimates of density.

Computer image processing and automatic counting and measuring of fouling organisms

The purpose of this study was to optimize the counting and measuring of marine fouling organisms on experimental panels using automated computer techniques. A script was developed that reduced the time required for the counting and measuring of marine fouling tubeworms by at least one order of magnitude over manual counts, with an error of five percent or less. Small, distinct tubeworms can be successfully counted by computer using a correction factor. Measurements of percentage cover or area should be made with larger tubeworms that have overlapping tubes.