Plectroglyphidodon Lacrymatus Research Articles

Phylogenetic analysis of ornamental Pomacentridae from the southern coast of West Java

Abstract. Pomacentridae has a wide distribution in Indonesia waters. Research on species richness of Pomacentridae has been carried out in some areas in Indonesia. However, there are no data about the relationships of Pomacentridae on the southern coast of West Java. This research aims to know the evolutionary kinship of Pomacentridae ornamental fish in Ujung Genteng and Taman Manalusu Beach, West Java. This research used a survey method with a judgment sampling technique. The parameters measured were the consistency index (CI) and character evolution of the resulting phylogenetic tree. Cladogram reconstructed based on maximum parsimony algorithm with 1000 bootstrap replicates in PAUP software. The result showed that the tree had a CI value of 0.6000 which indicated low homoplasy. Pomacentridae formed a monophyletic group when they compared with Chaetodon collare as outgroup. The Pomacentridae clade divided into two subclades. The first subclade consisted of Abudefduf indicus as a basal species, then Neoglypydodon bonang and Plectroglyphidodon lacrymatus have a closed kinship and diverged after Dascyllus trimaculatus, and then Abudefduf notatus and Abudefduf sexfaciatus have a close kinship and diverged after Abudefduf vaigiensis. The second subclade referred to as a basal group, and within this subclade, Chrysiptera brownriggii has a closely related to Chrysiptera unimaculata and diverged after Chromis opercularis.Keywords: Cladistics, damselfish, meristic, morphometric, Pomacentridae

Trophic ecology of the seagrass-inhabiting footballer demoiselle Chrysiptera annulata (Peters, 1855); comparison with three other reef-associated damselfishes

Many damselfishes (Pomacentridae) are herbivorous or omnivorous with an important contribution from different kinds of algae in their diet. They display different levels of territoriality and farming behavior, from almost non territorial to monoculture farmers. In addition, a few species inhabit seagrass meadows but, presently, none can be considered as seagrass-eating specialists. The footballer demoiselle, Chrysiptera annulata, is found in the seagrass meadows on the reef flat of the Great Reef of Toliara (Madagascar, Mozambique Channel). In the light of this unusual habitat for a pomacentrid, this study aimed to answer three questions: 1) What is the diet of C. annulata? 2) Do the resources supporting this diet include seagrass? 3) Does its trophic niche overlap those of other sympatric damselfishes (Pomacentrus trilineatus, Chrysiptera unimaculata and Plectroglyphidodon lacrymatus) living in close association with macrophytes or eating algae? Stomach content examination and stable isotope analysis showed that the footballer demoiselle is not a seagrass consumer but is an omnivorous/herbivorous species heavily relying on algal resources and small invertebrates. SIAR, a stable isotope mixing model, indicated it assimilated large amounts of turf algae, and various benthic or planktonic invertebrates in lower proportions. SIBER metrics revealed that the isotopic niche of the footballer demoiselle partly overlaps that of its congener, C. unimaculata, but not those of P. trilineatus and P. lacrymatus. Trophic strategies of C. annulata differed both from farming species such as P. lacrymatus and from less territorial herbivores such as P. trilineatus. Its seagrass meadow habitat on the Great Reef of Toliara allows the conquest of an unusual habitat for damselfishes and could limit competition with C. unimaculata, a species displaying the same territorial behavior and the same isotopic niche but living on the reef itself.

Effects of competition on the territorial behaviour of a farmer damselfish, Plectroglyphidodon lacrymatus (Perciformes: Pomacentridae).

Aggression and territory size of the farmer damselfish Plectroglyphidodon lacrymatus were examined in the presence of adjacent territories of conspecific and heterospecific farmers that maintain algal turf territories on the reefs of Anda, north-western Philippines. Plectroglyphidodon lacrymatus territories with no adjacent neighbours had a mean size of 1.2 m2 whereas those adjacent to conspecifics were 47% smaller. In contrast, the mean size of territories adjacent to a heterospecific farmer (i.e., Pomacentrus burroughi, Pomacentrus chrysurus) did not differ from that of solitary individuals. Aggression towards conspecific farmers (84% probability) was higher than heterospecific farmers (31%). The higher aggression towards conspecific farmers suggests that the energetic costs for defence increased, which may have caused a decrease in territory sizes. Despite the higher aggression towards conspecific farmers, the thickness and percentage cover of algae inside the territories of focal fish did not appear to vary according to type of neighbouring farmer although algal turf cover was higher and juvenile coral occurrence was lower inside than outside the territories. Our results show that the territorial behaviour of P. lacrymatus varies with conspecific and heterospecific farmers, which may influence their distribution and benthic habitat characteristics.

Defended territories of an aggressive damselfish contain lower juvenile coral density than adjacent non-defended areas on Kenyan lagoon patch reefs

Jewel damselfish, Plectroglyphidodon lacrymatus, aggressively defend small territories on coral reefs in which they cultivate lawns of edible macroalgae. Pairwise frequency counts showed that juvenile coral density was lower inside damselfish territories than that in adjacent non-defended areas on lagoon patch reefs in Kenya. These differences in coral density decreased as coral size increased. Direct farming effects of the damselfish and indirect inhibitory effects from higher algal densities inside territories are both thought to be potentially responsible for the results attained herein. Damselfish territories can occupy a large proportion of a coral reef; territorial behaviour in fish may have greater impacts on reef structure, in particular the resilience and growth rate of juvenile corals, than previously appreciated.

Factors Affecting Interspecific Aggression in a Year‐Round Territorial Species, the Jewel Damselfish

AbstractVertebrates live in complex species networks in which interspecific interactions are common. In some contexts, the aggressive behaviours shown in these interspecific interactions are very similar to those shown in intraspecific interactions. It is still an open question whether intra‐ and interspecific aggression share common causality. We studied a year‐round territorial species the jewel damselfish, (Plectroglyphidodon lacrymatus), which cultivate algae they feed on. Territory holders aggressively defend these algae that are an attractive resource for many other species. In this study, we recorded territorial aggression in free‐living individuals and recorded aggressive responses to a standardized territorial intrusion test in captive individuals. Field observations indicated that territorial aggression was selectively targeted towards food competitors. Independent of the size of the species, aggression was more frequent towards common species around their territories. This relationship was confirmed experimentally by confronting the jewel damselfish with novel objects to which the subjects were exposed either frequently or rarely. We suggest that jewel damselfish have to learn which species are competitors and therefore should be chased. In a standardized intrusion test with captive individuals, no significant differences were found in territorial responses towards intra‐ or interspecific intruders. Neither territorial aggression nor the intrusion showed any relationship with plasma androgen levels. Together, these data suggest that experience might be more important in non‐seasonal territorial aggression than circulating hormonal factors.

Damselfish territories as a refuge for macroalgae on coral reefs

Herbivory is widely accepted as a key process determining the benthic community structure and resilience of coral reefs. Recent studies have mostly focused on the importance of roving herbivorous fishes in ecosystem processes. Here, we examine the role of territorial damselfish in shaping patterns of macroalgal distribution based on benthic surveys and macroalgal bioassays. The territory composition and effect of resident damselfish on the removal of Sargassum bioassays were quantified for six species of damselfish on Lizard Island, a mid-shelf reef in the northern Great Barrier Reef (GBR). The functional composition of algal communities within territories varied markedly among species. The territories of four species (Dischistodus perspicillatus, Dischistodus pseudochrysopoecilus, Plectroglyphidodon lacrymatus, and Stegastes nigricans) were characterized by algal turfs, while the territories of two species (Dischistodus prosopotaenia and Hemiglyphidodon plagiometopon) were characterized by foliose and leathery brown macroalgae. Sargassum, a generally rare alga on mid-shelf reefs, was a particularly common alga within D. prosopotaenia territories on the leeward side of the island but absent within their territories on the windward side of the island. D. prosopotaenia was the only species to retain the transplanted Sargassum, with only a minimal reduction in Sargassum biomass (1.1%) being recorded within their territories at both leeward and windward sites over a 24-h period. In contrast, reductions in Sargassum biomass were high in areas adjacent to D. prosopotaenia territories (83.8%), and within and adjacent to the territories of the five remaining damselfish species (76.2–92.5%). Overall, only one of the six damselfish species provided a refuge for leathery brown macroalgae and may facilitate the development of this macroalgae on mid-shelf reefs of the GBR

Evidence of a geographically variable competitive mimicry relationship in coral reef fishes

AbstractIn Kimbe Bay, Papua New Guinea, juvenile surgeonfish Acanthurus pyroferus have been shown to gain access to food resources defended by the damselfish Plectroglyphidodon lacrymatus by mimicking a pygmy angelfish, Centropyge vrolikii, that does not compete with the damsel for food. I tested whether A. pyroferus juveniles gain the same competitive advantage from mimicking a different pygmy angelfish, Centropyge flavissima, in Moorea, French Polynesia. Through abundance and substrate surveys, behavioral observations and stomach content analyses, I demonstrate that in Moorea, mimicry of Ce. flavissima does not provide A. pyroferus with access to damselfish Stegastes nigricans territories; Ce. flavissima models are always attacked upon territory entry and A. pyroferus mimics avoid damsel territories. Damselfish aggression toward the model angelfish cannot be attributed to overabundance of the deceptive mimic; instead, aggression can best be explained by the fact that Ce. flavissima competes with damsels in Moorea by consuming their algal turfs, making them inappropriate models for competitive mimics. Juveniles of many Indo‐Pacific surgeonfishes appear to mimic pygmy angelfishes; I suggest that these mimics' success in gaining access to damselfish territories is geographically variable and may be determined by the extent to which mimics, models and receivers overlap in resource use at a given site. This mimicry complex may thus present an excellent illustration of the geographic mosaic model of coevolution.

FRESHWATER AND MARINE DIATOMS FROM THE WESTERN PACIFIC ISLANDS OF YAP AND GUAM, WITH NOTES ON SOME DIATOMS IN DAMSELFISH TERRITORIES

First records of diatoms from Yap, Federated States of Micronesia, are presented, including freshwater samples from an initial assessment of collections made in streams and estuaries and marine samples from nearby coral reefs during a brief survey of the Wa'ab group of islands. Thirty-eight species were documented from Yap; of these 13 had been reported from Guam. In addition we report 25 new records for Guam. The Guam records include especially some large chain-forming Coscinodiscophyceae and Mediophyceae, for which we have new observations on living cells and their habitats: the marine Chrysanthemodiscus floriatus, Stictocyclus stictodiscus, Biddulphiopsis membanacea, Lampriscus shadboltianum var. crenulata, L. orbiculatum, and Biddulphia biddulphiana; and the freshwater Terpsinoë musica. Diatoms have recently been shown to be significant components in the diets of some farmer fish and in Guam C. floriatus and B. membranacea, among others, commonly form blooms or dense mixed communities of epiphytes on the seaweed turfs in territories of these damselfish, including Plectroglyphidodon lacrymatus and Stegastes nigricans.

Trophic niches of thirteen damselfishes (Pomacentridae) at the Grand Récif of Toliara, Madagascar

The damselfishes, with more than 340 species, constitute one of the most important families that live in the coral reef environment. Most of our knowledge of reef-fish ecology is based on this family, but their trophic ecology is poorly understood. The aim of the present study was to determine the trophic niches of 13 sympatric species of damselfishes by combining stable isotope (δ15N and δ13C) and stomach content analyses. Isotopic signatures reveal three main groups according to their foraging strategies: pelagic feeders (Abudefduf sexfasciatus, A. sparoides, A. vaigiensis, Chromis ternatensis, C. dimidiata, Dascyllus trimaculatus and Pomacentrus caeruleus), benthic feeders (Chrysiptera unimaculata, Plectroglyphidodon lacrymatus and Amphiprion akallopisos) and an intermediate group (D. aruanus, P. baenschi and P. trilineatus). Stomach contents reveal that planktonic copepods and filamentous algae mainly represent the diets of pelagic feeders and benthic feeders, respectively. The intermediate position of the third group resulted from a partitioning of small planktonic prey, small vagile invertebrates and filamentous algae. In this last feeding group, the presence of a wide range of δ13C values in P. trilineatus suggests a larger trophic niche width, related to diet-switching over time. Some general considerations about the feeding habits of damselfishes reveal that their choice of habitat on the reef and their behavior appear to be good predictors of diet in this group. Benthic (algae and/or small invertebrates) feeders appear to be solitary and defend a small territory on the bottom; zooplankton feeders remain in groups just above the reef, in the water column.

Resource use and impact of three herbivorous damselfishes on coral reef communities

Territorial damselfish are considered to be functionally important herbivores on coral reefs, promoting the abundance of preferred algae and depleting corals through a variety of ‘farming’ activities. However, the composition of algal and coral communities inside territories and patterns of feeding selectivity are known for only a few species. Here we compare substrata inside and next to territories of Plectroglyphidodon lacrymatus, P. dickii and Stegastes nigricans, 3 common damselfish in Papua New Guinea, and interpret patterns in relation to diets and patterns of feeding selectivity. The coral assemblages inside territories differed among fish species and also between defended and non-defended areas. Live corals dominated P. dickii territories, while those of P. lacrymatus and S. nigricans were primarily associated with algal substrata. Territories of P. lacrymatus were similar in coral composition to adjacent areas, while those of P. dickii and S. nigricans were associated with particular coral taxa. Territories of the 3 damselfish were similar in algal composition, with mixed turf algae (primarily blue-green algae Polysiphonia spp. and other filamentous red algae) more prominent inside territories and crustose coralline algae more prominent outside. Diets for the 3 species were also similar, as each species was primarily herbivorous and diets consisted of diatoms, blue-green algae, Polysiphonia spp. and other filamentous red algae. An experimental removal of P. lacrymatus showed that they promoted epiphyte loads without influencing macro-algal or coral cover. Our results suggest that while these 3 species of damselfish vary in their interactions with coral reef habitat, they selectively cultivate a similar range of epiphytic food algae on different substrata.

Sound production in two species of damselfishes (Pomacentridae): Plectroglyphidodon lacrymatus and Dascyllus aruanus

Agonistic sounds of two pomacentrid species, Plectroglyphidodon lacrymatus and Dascyllus aruanus, were recorded in captivity. Plectroglyphidodon lacrymatus produced trains of 2–5 pops, each composed of 18–25 cycles, with an average duration of 56 ms; most energy ranged from c. 100 to 1000 Hz. Dascyllus aruanus produced pops and chirps. Pops were generally composed of a single pulse, with 2–14 peaks and an average duration of 6·7 ms. Pops contained energy >4 kHz, and peak frequency ranged from 680 to 1300 Hz. Chirps consisted of trains of 12–42 short pulses of three to six cycles, with durations varying from 0·6 to 1·27 ms; peak frequency varied from 3400 to 4100 Hz. Sound production in P. lacrymatus suggested that pomacentrids are derived from an ancestral taxon capable of sound production and that this capacity is a synapomorphy for the family. Although in the Pomacentridae, pops are typically composed of a single pulse, which is longer and higher pitched than chirps composed of a series of shorter pulses, D. aruanus chirps were higher pitched than its pops. Thus, acoustic variation in the genus Dascyllus is probably not more restricted than in the Pomacentridae.

A preliminary study of development of the buccal apparatus in Pomacentridae (Teleostei, Perciformes)

AbstractThis study compares, in five species of Pomacentridae (Chromis viridis, Dascyllus flavicaudus, Chrysiptera glauca, Pomacentrus pavo, Plectroglyphidodon lacrymatus), the changes in cephalic skeletal structures between settling larvae and adults living on the reef. Variations were studied in the suspensorium, the opercle, the mandible, the premaxillary bone and the teeth. Comparisons of the feeding apparatus enabled two different types of feeding to be distinguished in adults: suction feeding and grazer sucking. Adult C. viridis and D. flavicaudus have a high suspensorium, a well-rounded mouth during jaw opening and caniniform teeth. These two species can be considered to be suction feeders. On the other hand, adult C. glauca, P. pavo and P. lacrymatus have less developed suspensoria, opercles and ascending process of the premaxillar, and present incisiform teeth. These three species appear to be grazer suckers. However, the larvae of all five species present an unimodal way of feeding, defined as ram-suction. Differences between larvae and adults appear clearly to be related to their ecology. The increasing variation presented in feeding apparatus during the settlement phase could be linked to diversification leading to occupancy of different ecological niches.

Effects of territorial damselfish on cryptic bioeroding organisms on dead Acropora formosa

Many damselfishes exclude other grazers from their territories and “farm” filamentous algae within their territories. In this study the indirect effect of damselfish territories on faunal composition and abundance of internal bioeroders of dead Acropora formosa (Dana, 1846) was investigated in territories of two damselfish species, Stegastes nigricans (Lacepède, 1802) and Plectroglyphidodon lacrymatus (Quoy and Gaimard, 1825). S. nigricans tends to be more protective and defend their territories more aggressively than P. lacrymatus. Newly killed branches of A. formosa were placed inside and outside damselfish territories, for 1 or 2 years, at a coral reef near Zanzibar, Tanzania. As predicted, the coral branches became covered with more filamentous algae in the S. nigricans territories than in the controls, with intermediate levels in the P. lacrymatus territories. Among the internal bioeroding fauna, polychaetes were by far the most common group. In total, there were significantly more borers in the first year than the second, which was mainly due to a high abundance of sabellids. Furthermore, sabellids were significantly more abundant in control areas and in the P. lacrymatus territories compared to the S. nigricans territories. However, many other genera showed the opposite pattern, with more polychaetes in the fish territories compared to the controls. There was also a clear difference in assemblage structure between S. nigricans territories and controls. Thus, we found strong effects of whether a piece of coral was placed inside or outside a damselfish territory on the abundance of many of the bioeroding taxa. We discuss multiple reasons for these indirect effects of the territories, including that deposit feeding bioeroders may benefit from the dense algal turf found inside the territories whereas suspension feeding bioeroders may benefit from substrate with less filamentous algae found outside territories. Considering our results in the context of the large areas of coral reefs that typically are defended as territories by damselfishes, these fish are likely to have a considerable impact on the boring community of a coral reef.

Low efficiency of dietary carbon and nitrogen conversion to growth in an herbivorous coral‐reef fish in the wild

Annual ingestion and body growth have been estimated for average‐sized adult (mean s.l. 62.7 mm) jewel damselfish. Plectroglyphidodon lacrymatus (Quoy et Gaimard), on a shallow fringing reef of southern Papua New Guinea. Mean ingestion (calculated from daily algal‐food consumption in winter, the relationship between water temperature and feeding activity, and C, N and P contents of algal food) was 304.3gC year, 20.4gN year−1 and 3.5gP year−1 for this herbivorous fish. Mean body‐growth rates for the fish were 5.7 mm year−1, from SEM analysis of sagittal‐otolith microstructure, and 6.2 mm year−1 from a mark‐release‐recapture study in the wild. Based on C and N analyses of whole fish and the dry‐weight/s.L. relationship, the gross growth efficiency of these fish was 0.2% for C and 0.5% for N. These very low efficiencies indicate that although P. lacrymatus ingests and absorbs a high proportion of algal production in its territory, only a small part of the assimilation goes into body growth and is thus potentially available to piscivorous fish higher in the food‐chain.

Ecological correlates of foraging periodicity in herbivorous reef fishes of the Coral Sea

Diurnal feeding activity patterns of five herbivorous reef fishes were studied at two sites in the Coral Sea, Motupore Island and Davies Reef. A marked peak in feeding activity in the afternoon was found for the damselfishes Pomacentrus flavicauda Whitley, Stegastes apicalis (De Vis) and Plectroglyphidodon lacrymatus (Quoy et Gaimard), and the surgeonfishes Acanthurus lineatus (L.) and Ctenochaetus striatus (Quoy et Gaimard). Pomacentrus flavicauda and Ctenochaetus striatus exhibited weak territorial aggression, but afternoon foraging was as marked in them as in the other species. Pomacentus flavicauda, Stegastes apicalis, Plectroglyphidodon lacrymatus and Acanthurus lineatus fed on the algal turfs within their territories. Although some Ctenochaetus striatus on the outer reef flat foraged on algal turfs, most individuals fed over crustose-coralline-algal surfaces and rocks with diatom and sparse filamentous-algal coverage; afternoon peaks of feeding were found in both cases. Afternoon foraging was not found to be a metabolic response to diurnal temperature increase, and did not correlate directly with average tidal, wind (water movement), or light-intensity patterns. Although ambient dissolved-oxygen maxima did correspond with afternoon foraging, there was no evidence that oxygen was limiting to fish metabolism and no sign was found of an intrinsic respiratory rhythm in one species, Plectroglyphidodon lacrymatus. Assuming negligible exudation of soluble organics, measurements of community net oxygen flux by turf algae indicate that photosynthetic carbon accumulated through the daytime at both sites in the Coral Sea. At Motupore Island, organic matter tended to rise and crude-fibre levels fell diurnally in turf algae collected from the reef, demonstrating a measurable increase in more-assimilable carbon later in the day. Afternoon foraging may be an adaptation by herbivorous reef fishes to the diurnal build-up of photosynthate in productive microalgal communities, particularly turfs.

Efficient uptake of algal production by a single resident herbivorous fish on the reef

Daily ingestion in the winter by the herbivorous territorial reef-dwelling jewel damselfish Plectroglyphidodon lacrymatus (Quoy et Gaimard) was measured at Motupore Island, Papuan Coastal Lagoon, southern Papua New Guinea, using two independent techniques. A gut-filling/feeding-activity method gave a rate of 1.52 g dry wt · day −1 for each fish, while a defecation/absorption method gave 1.62 g dry wt · day −1; ingestion was taken to be the average of these two estimates (1.57 g dry wt · day −1). The mean planar area of territories was 0.43 m 2, and the mean surface-area index of the outer reef-flat/upper reef-slope sites involved was 1.82 m 2 · m −2. After measuring the C (39.9 %), N (4.3 %), and P (0.43 %) contents of the food, in the winter the fish was found to take up daily 1.43g C · m −2, 0.14 gN ·m −2 and 0.014 gP·m −2 of territory. Thus, the C: N: P atomic ratio of the turf-algal food was 263: 22: 1. Using laboratory respirometry, and surface light intensity and extinction data, daily net turf-algal production in the winter was 1.09–1.10gC · m −2 on experimental plates, and 1.98–2.00 g C · m −2 in territories. Thus P. lacrymatus consumed > 70% of the net community C fixation in its territory in the winter. The fish ingested an especially large part of the N (91%; 42% of P) incorporated into the algal community, and, thus, “spatially focused” fluxes particularly of N within its territory. Substantial quantities of C, N, and P(310 mg C · m −2 day −1; 13 mg N · m −2 · day −1; 6 mg P · m −2 · day −1) were defecated and probably contributed to temporary pools of these elements in the reef interstitial water. Dietary absorption by the fish was high: 91.7% for N (76.5% in summer), 78.4% for C (58.3% in summer), and 61.4% for P (only summer data available). Organics were absorbed in the first 25% of the gut length. P. lacrymatus ingested 15% of its body N, 24% of C, and 37% of total material daily by mass.

Recruitment, loss and coexistence in a guild of territorial coral reef fishes.

Eupomacentrus apicalis, Plectroglyphidodon lacrymatus, and Pomacentrus wardi are territorial pomacentrid fishes which occupy contiguous individual territories within rubble patches on the shallow reef slope. Loss of residents, which is non-seasonal (except for juvenile Po. wardi), results in reallocation of space in rubble patches among the species. This reallocation is random in the sense that sites previously held by one species will not be more likely than any other sites to be reoccupied by that species or to be occupied by any other particular species. The results of a 38 month study of three neighbouring patches are used to determine patterns of recruitment, survivorship, and loss for each species. The rate of recruitment of fish is proportional to the area of the rubble patch, and is seasonal in at least one of the species. About half the recruits are juveniles and young adults from other sites. The others are newly settled from the plankton. Total space used in a rubble patch does not vary significantly during the 38 month period. Po. wardi recruits and is lost at higher rates than the other species and its survivorship is significantly lower. Juvenile Po. wardi are lost at a greater rate than are adults, and their loss rate varies seasonally. The other species are similar to one another in having low recruitment and loss rates, and correspondingly high survivorship. The data are used in a critical assessment of several competing hypotheses to explain the coexistence of these fish. The available data are most closely compatible with the chance allocation or lottery hypothesis, but a definitive conclusion is not possible, and is probably beyond current experimental techniques.

Chance patterns of demographic change in populations of territorial fish in coral rubble patches at heron reef

Individuals of three permanently territorial fishes, Eupomacentrus apicalis (De Vis), Plectroglyphidodon lacrymatus (Quoy & Gaimard), and Pomacentrus wardi (Whitley), occur in contiguous territories on rubble patches along the shallow reef slope at Heron reef, Great Barrier Reef. Demographic changes over 31/2 years are examined in populations of each species in each of three nearby rubble patches. All species were represented in each patch. Changes to the habitat provided by the patches, and changes in the total area in each patch occupied by members of each species are also assessed. Despite evidence that the three patches provided relatively constant environments during the period of study, there were pronounced variations in numbers of certain species in each patch. There were different patterns of change in numbers in each patch, and this change was sufficient in most cases for the amount of space occupied by a species to vary by a factor of two during the period. The results strongly support the view that these species of fish are competitive near-equals which coexist in rubble patches by means of a ‘lottery’ competition by colonists for living sites.