Terry J. Donaldson

Threatened fishes of the world: Cheilinus undulatus Rüppell, 1835 (Labridae)

Common names: Maori, Napoleon or humphead wrasse (English), so-mei (Hong Kong, southern China and Taiwan) and numerous other names throughout the Indo-West Pacific region. Conservation status: Listed as ‘vulnerable’ in the IUCN 1996 Red Data Book because of severe declines in sizes and numbers in SE Asia attributed to heavy exploitation for the live reef fish trade (LRFT). Identification: A distinctive species and among the largest of all reef fishes. Adults are blue/green with large scales and a yellow posterior margin to the caudal fin; small individuals are pale with black markings. Can attain a TL of 250 cm and Wt of 191 kg; D IX, 10; A III, 8; P 12; ll 14–16 + 7–8; GR 6–7 + 13–14 = 19–21; depth 2.2–2.7, increasing with age. Large adults develop a prominent bulbous hump on the forehead and thick, fleshy lips (Myers 1999). Drawing from FAO Species Identification Sheets used by permission. Distribution: Tropical and sub-tropical Indo-West Pacific (Myers 1999). Abundance: Observed frequently as solitary individuals, in male–female pairs (i.e. Myers 1999) or in social groups consisting of a single male, 2–7 smaller adults, and several juveniles. This species is uncommon wherever it occurs (Y. Sadovy, M. Kulbicki, P. Labrosse, Y. Letourneur, P. Lokani & T.J. Donaldson unpublished). Habitat and ecology: Occurs along steep outer reef slopes, channel slopes, and lagoon reef slopes at depths of 2–60 m. Adults observed hovering off coral reef slopes and walls, cliff walls, or in boulder-rich habitats, frequently seeking shelter in caves or crevices, especially at night, while juveniles have been observed in coral thickets within lagoons or on deeper reef flats (Myers 1999). This species feeds primarily upon molluscs, but its diet includes crustaceans, heavy-shelled gastropods, sea urchins, brittle stars, starfishes (including crown-of-thorns starfish, Acanthaster planci), and fishes. Because its diet includes fishes, it may be ciguatoxic in some areas (Randall et al. 1978, Myers 1999). Reproduction: Forms small mating groups or spawning aggregations (Donaldson 1995, Sadovy et al. unpublished). Spawning is paired with production of pelagic eggs. The smallest size at sexual maturation is between 40–60 cm TL and some males develop directly from juveniles; diandric protogyny, found in many other family members, has been confirmed for this species (Sadovy et al. unpublished). Threats: These include: (1) intense and species-specific (i.e. selective) fishing for the LRFT with juveniles the predominant size range marketed in Hong Kong (Lee & Sadovy 1998); (2) capture by destructive fishing, especially cyanide; (3) spearfishing at night with SCUBA or hookah gear; (4) illegal fishing; (5) poor or no management at most localities; (6) continued trade because its high value increases with rarity, thus encouraging continued fishing even at low population numbers. Conservation action: This species is, or has been, fully or partly (i.e. for certain size classes) regulated, protected or banned from export in Australia, Indonesia, Maldives, Philippines (Palawan), Palau, and the Solomon Islands. Conservation recommendations: (1) Implement a moratorium on fishing for export. (2) Fund research on Cheilinus undulatus ecology and behavior, and especially population structure. (3) Create marine reserves that incorporate key habitat, such as spawning areas. (4) Educate resource managers, consumers and the general public on the importance of conserving this species. Remarks: The large size attained by this species suggests that it may be long-lived, and if typical of reef fishes of similar size and biology, it is expected to have low replacement rates and to be particularly vulnerable to fishing pressure. There is little chance that culturing will remove pressure on wild-caught individuals in the near future because it is difficult to culture. This species’ importance to divers means that the humphead wrasse does much to promote conservation interest in reef areas and is of high tourism value. This is Contribution No. 447 of the University of Guam Marine Laboratory.

Threatened fishes of the world: Bolbometopon muricatum (Valenciennes 1840) (Scaridae)

Common names: Bumphead parrotfish, giant humphead parrotfish, green humphead parrotfish (English) and numerous other names throughout the Indo-West Pacific region. Conservation status: Listing pending on the IUCN Red List. Identification: The largest species of parrotfish, reaching 130 cm total length, and 46 kg total weight; D IX, 10; A III, 9; P 15-16; pre-D 3-5; GR 16-18; 3 scale rows on cheek; depth 2.0–2.5. Adults are olive or blue green to slate grey in colour, the head is yellowish to pink. Juvenile body colour ranges from green to brown; there are five vertical rows of white spots (Myers 1999). Adults develop a prominent bulbous bump on the forehead and the dental plates are exposed. Distribution: Tropical and subtropical coral reef habitat, central and western Pacific to Indian Ocean and Red Sea (Myers 1999). Abundance: Locally patchily distributed, adults always found in small shoals (≤40 individuals). Historically, it was common to abundant throughout much of its range. Now it is abundant only in Australia, Papua New Guinea, Solomon Islands and few other oceanic islands and is locally common in the Red Sea and New Caledonia. At other locations it is now uncommon or rare, and is virtually extinct in Guam, the Marshall Islands parts of Fiji and East Africa (Bellwood et al. 2003). Habitat and ecology: Wide-ranging on shallow (1–15 m deep) barrier and fringing reefs during daytime, nocturnally they rest in caves or in shallow sandy lagoon flats (typically <50 m). Juveniles are found in seagrass beds in lagoons and reef flats. Feeds on benthic algae and live corals; adult individuals are estimated to consume 5–6 tonnes of these corals per year, producing a considerable amount of sediment, and influencing significantly coral reef structure (Bellwood et al. 2003). Reproduction: Frequently aggregates at promontories, gutters and channel mouths or passes at or near the outer reef slope for pelagic spawning (Johannes 1981; Gladstone 1986) during a monthly lunar cycle. Courtship and spawning has been reported to occur in early morning (Gladstone 1986) although may occur at other times (Johannes 1981). Threats: Shoaling and group resting behaviour render this species highly vulnerable to spear fishing, particularly at night-time. Conservation action: Some protection afforded by regulations restricting night-time spear fishing or spear fishing with compressed air (e.g. American Samoa). Conservation recommendations: (1) Implement of a moratorium on commercial fishing and export. (2) Educate resource managers, fishers, consumers and the general public on the importance of conserving this species. (3) Create and enforce larger marine reserves that incorporate key habitat. (4) Further research on population ecology and behaviour. Remarks: Large size attained and known longevity indicate low replacement rates and high vulnerability to fishing pressure. This species appears to be of considerable functional importance, as it is the major bioeroder on coral reefs and may maintain ecosystem resilience. We acknowledge the Food and Agriculture Organization of the United Nations for permission to reproduce here their drawing of this species. This is Contribution No. 559 of the University of Guam Marine Laboratory and No. 23 of the IMA-Integrative Biological Research Program. NKD is grateful to Natural Environment Research Council, U.K. and Defra (MFD 0729) for funding his contribution to this research.

Insular Freshwater Fish Faunas of Micronesia: Patterns of Species Richness and Similarity

Freshwater fishes are an important but relatively little known component of the highly diverse fish fauna of Micronesia. Localities supporting communities of freshwater fishes include large high islands, with considerable habitat complexity, and smaller low islands, such as atolls and raised coral islands, with limited freshwater habitat. Both types of islands may support species with adult life history styles that are (a) amphidromous and catadromous, (b) euryhaline (often estuarine), or (c) marine species which enter freshwater from time to time. We compared patterns of species richness and similarity between Micronesian localities for amphidromous and catadromous, euryhaline and marine species (ACEM) pooled, and for amphidromous and catadromous species (ACFW). Species richness of both ACEM and ACFW fishes was greatest on larger high islands compared to smaller high and all low islands. Cluster analysis of similarity indices for ACEM species between localities revealed two faunal components: high islands and low islands. High islands were further partitioned into a Caroline Islands cluster and a separate Mariana Islands cluster. Cluster analysis of ACFW species was more complex. One cluster consisted of a low island and a small high island, both in the Carolines chain and with limited freshwater habitat. The second cluster was partitioned into high islands and low islands that reflected influences of both size and geographical location.

High islands versus low islands: a comparison of fish faunal composition of the Palau Islands

High islands, with potentially greater habitat diversity, are expected to have greater species richness and diversity compared to low islands, typically atolls and coral islands of lower habitat diversity, within the same geographical area. Patterns of species similarity, richness, and diversity were compared among coral reef fishes between the low island of the Southwest Palau Islands (SWPI), and the low and high islands of the Main Palauan Archipelago (MPA). Data from diurnal visual transects accounted for approximately 64% and 69% of the shorefish faunas known from the SWPI and MPA, respectively. Two distinct fish faunas were representative of low and high islands. The first was confined to the coral islands of the SWPI. The second was partitioned into both low and high islands of the MPA, and Helen Reef, a large atoll in the SWPI. The second type was clustered into atolls, low islands with atoll-like barrier reef systems, a coral island, and three high island systems, one with an extensive barrier reef system. Contrary to the prediction that high islands, with relatively greater habitat diversity, would have greater species richness and diversity, species richness and diversity were greatest at Kossol, a large atoll-like ‘low island’ locality at the northern end of a high island in the MPA, followed by two atolls, Kayangel (MPA, north of Kossol) and Helen Reef. In contrast, species richness and diversity were lower at high island localities and lowest at small coral islands. These results suggest that habitat diversity for reef fishes increases as a function of increasing area regardless of whether the locality is a high or low island.

Habitat association and depth distribution of two sympatric groupers of the genus Cephalopholis (Serranidae: Epinephelinae)

Abstract Habitat association and depth distribution of two sympatric coral reef groupers of the genus Cephalopholis were examined at Rota, Mariana Islands. The two species are similar in body size, morphology, and social organization. In this study, they differed in their association with habitat and microhabitat and in depth distribution. Cephalopholis spiloparaea occurred on the reef slope between the reef terrace and deep sand flats at depths between 15 and 26 m. This species was associated mainly with Porites rus corals. Cephalopholis urodeta occurred largely on the upper reef terrace at 1–12 m. This species was associated mainly with coral pavement. The observed pattern of segregation might be the result of competitive or noncompetitive interactions or of phylogenetic constraints, but the exact mechanism or combination thereof remains unknown.

Cluster dynamics in Maristentor dinoferus, a gregarious benthic ciliate with zooxanthellae and a hypericin-like pigment, in relation to biofilm grazing by the fish Ctenochaetus striatus

The large symbiotic ciliate Maristentor dinoferus (Heterotrichida: Maristentoridae) has an abundant, potentially toxic pigment that makes the cells look black, and it forms clusters making it easy to see in the field. In situ observations of vast Maristentor populations during three bloom years provided insights into the behavioral ecology of the Maristentor holobiont and circumstantial evidence for feeding deterrence. Maristentor migrated onto limestone tiles that were also suitable for development of biofilm, which was consumed by the fish Ctenochaetus striatus. We photodocumented several aspects of Maristentor movement in situ, including a diurnal rhythm of dispersal and re-clustering in the morning, a period of “cocktail party dynamics” that resulted in larger, fewer clusters over the afternoon, and responses to two different disturbances: (1) rapid dispersal–re-clustering when tiles were moved; and (2) swimming off the surface and photoaccumulating on the brightest and highest part of a container when Maristentor was enclosed. Although Maristentor is considered benthic, its abilities to swim rapidly, to photoaccumulate, and to form clusters hanging from a water surface hint that they may also exist in the hyponeuston. Although interaction between Maristentor and Ctenochaetus may not be common, it indicated ways in which the behavior of Maristentor could help defend it from grazing. First, during the morning diaspora and re-clustering, which coincided with a period when Ctenochaetus was not feeding, Maristentor tended to accumulate on thinner biofilm, including edges and previously-grazed areas. Secondly, analysis of bite marks suggested that this fish tended not to select thin biofilm and that, despite rapid feeding, it tended to avoid larger Maristentor clusters.

THE ROLE OF CHELIPED AUTOTOMY IN THE TERRITORIAL BEHAVIOR OF THE FRESHWATER PRAWN MACROBRACHIUM LAR

Abstract The role of cheliped autotomy in the territorial behavior of the freshwater prawn Macrobrachium lar was analyzed to determine whether or not prawns modified their defended territory size based on cheliped autotomy. Territory size measurements were recorded for captive prawns interacting in artificial tank habitats and were logged according to the locations where agonistic encounters occurred and aggressive pressures were equal. All prawns used in this study were mid-intermolt males in the size class 9.0 ± 1.5 cm, with staged encounters occurring under three treatment conditions in which fully intact prawns were matched against animals possessing no chelipeds, one cheliped, or two chelipeds (fully intact). Separate experiments for each condition were completed with four prawns per tank per 14-day trial and were run a total of three times each. The defended territory size mean for the Control prawns (matched only against other intact animals) did not differ significantly from one quarter of the total tank area. The mean territory sizes for prawns within or between each treatment condition was significantly different. Prawns with one or two chelipeds autotomized each defended significantly smaller territories than other male prawns of equal size, but with both chelipeds intact. Our results show that the presence of chelipeds allowed the defense of larger territories compared with the territories defended by prawns with one or both chelipeds autotomized.