Coral Rubble Habitats Research Articles

Forever fissiparous: asexual propagation and stable demography in a tropical and geographically isolated asterinid sea star

Sea stars of the family Asterinidae are well known for their diverse life history strategies encompassing sexual reproduction through various larval forms, while others, all multi-armed species, through clonal asexual reproduction. For at least 25 years, a geographically isolated population of the minute (radius < 7 mm) tropical Pacific fissiparous asterinid, Ailsastra heteractis, has been locally abundant in a shallow water coral rubble habitat at One Tree Island, southern Great Barrier Reef. The population biology of this sea star was investigated over 14 years to characterise its asexual reproduction through fission (splitting in half) and to determine whether a size threshold is reached for an expected switch to sexual reproduction. Fission followed by regeneration was the dominant propagation mechanism generating individuals that varied in arm number (2–7) and length (0.5–6.9 mm). Recently split individuals were present year round with regenerating individuals being the most prevalent body form. Growth rates and fission activity, as measured by mean arm length, varied among months but with no overall pattern. Analyses of arm length data based on season indicated that fission activity was lowest in autumn. There was a positive correlation between the incidence of fission and air and water temperature with a decrease in the proportion of recently split individuals in winter and an increase in summer. Fission was present in all size classes with no evidence of a switch to a larger sexual morphotype with growth. Juvenile recruitment from sexual reproduction was not evident. Extensive searches did not reveal the presence of other populations of A. heteractis. The absence of recruitment and reproductive organs coupled with a stable population demography indicates that propagation by fission is the only reproductive mechanism for the A. heteractis population.

Revision of the spider crab genus Sargassocarcinus Ward, 1936 (Crustacea: Brachyura: Epialtidae)

The Western Pacific epialtid genus Sargassocarcinus Ward, 1936, is revised. The genus had been regarded as monotypic but is here shown to contain three species: S. sublimis (Rathbun, 1916), S. cristatus (Balss, 1924), and S. foliatus Ward, 1936 (type species). The many unusual characters possessed by Sargassocarcinus are figured and discussed; and diagnostic features of the three species are clarified. The taxonomy of the three species and aspects of their ecology are discussed. Sargassocarcinus species are found free-living on coral rubble habitats and not associated with macrophytic algae.

Individual differences in activity and habitat selection of juvenile queen conch evaluated using acceleration biologgers

Fine-scale differences in behaviour and habitat use have important ecological impli- cations, but have rarely been examined in marine gastropods. We used tri-axial accelerometer loggers to estimate activity levels and movement patterns of the juvenile queen conch Lobatus gigas (n = 11) in 2 habitat types in Eleuthera, The Bahamas. In 2 manipulations in nearshore areas, queen conchs were equipped with accelerometers and released in adjacent coral rubble or sea- grass habitats. Queen conchs were located approximately every 6 h during daylight by snorkel- ing, to measure individual differences in linear distance moved, and after 24 h they were relocated to an alternate habitat (24 h in each habitat). We found significant inter-individual variability in activity levels, but more consistent levels of activity between the 2 habitat types within individual queen conchs. Four (36%) of the individuals placed in seagrass moved back to the adjacent coral rubble habitat, suggesting selectivity for coral rubble. Individuals showed variable behavioural responses when relocated to the less preferable seagrass habitat, which may be related to differ- ing stress-coping styles. Our results suggest that behavioural variability between individuals may be an important factor driving movement and habitat use in queen conch and, potentially, their susceptibility to human stressors. This study provides evidence of diverse behavioural (activity) patterns and habitat selectivity in a marine gastropod and highlights the utility of accelero meter biologgers for continuously monitoring animal behaviour in the wild.

All things in moderation: using formalin to coerce leucothoid amphipods out of the rubble (Crustacea: Amphipoda: Leucothoidae)

Collection of small (<12 mm) inquilinous animal species living deep in coral rubble can be difficult. Elutriation or swirling of coral rubble samples is successful, yet leaves many animals undisturbed in crevices of the rubble. Adding a small amount of formalin to a rubble sample before elutriation greatly increases the yield of such animals, although formalin is often avoided when collections are to be used for molecular studies. Focusing on leucothoid amphipods, detailed collection methods are given for obtaining these cryptic amphipods from coral rubble habitats. Using formalin in moderation facilitates the collection of hard to capture nestling and inquilinous species. These collection methods leave the amphipods alive with their DNA undamaged for successful extraction and amplification.

Rising CO2 concentrations affect settlement behaviour of larval damselfishes

Reef fish larvae actively select preferred benthic habitat, relying on olfactory, visual and acoustic cues to discriminate between microhabitats at settlement. Recent studies show exposure to elevated carbon dioxide (CO2) impairs olfactory cue recognition in larval reef fishes. However, whether this alters the behaviour of settling fish or disrupts habitat selection is unknown. Here, the effect of elevated CO2 on larval behaviour and habitat selection at settlement was tested in three species of damselfishes (family Pomacentridae) that differ in their pattern of habitat use: Pomacentrus amboinensis (a habitat generalist), Pomacentrus chrysurus (a rubble specialist) and Pomacentrus moluccensis (a live coral specialist). Settlement-stage larvae were exposed to current-day CO2 levels or CO2 concentrations that could occur by 2100 (700 and 850 ppm) based on IPCC emission scenarios. First, pair-wise choice tests were performed using a two-channel flume chamber to test olfactory discrimination between hard coral, soft coral and coral rubble habitats. The habitat selected by settling fish was then compared among treatments using a multi-choice settlement experiment conducted overnight. Finally, settlement timing between treatments was compared across two lunar cycles for one of the species, P. chrysurus. Exposure to elevated CO2 disrupted the ability of larvae to discriminate between habitat odours in olfactory trials. However, this had no effect on the habitats selected at settlement when all sensory cues were available. The timing of settlement was dramatically altered by CO2 exposure, with control fish exhibiting peak settlement around the new moon, whereas fish exposed to 850 ppm CO2 displaying highest settlement rates around the full moon. These results suggest larvae can rely on other sensory information, such as visual cues, to compensate for impaired olfactory ability when selecting settlement habitat at small spatial scales. However, rising CO2 could cause larvae to settle at unfavourable times, with potential consequences for larval survival and population replenishment.

In situ observations of fish associated with coral reefs off Ireland

The abundance and behaviour of fish on and around coral reefs at Twin Mounds and Giant Mounds, carbonate mounds located on the continental shelf off Ireland (600–1100 m), were studied using two Remotely Operated Vehicle (ROV) dives. We recorded 30 fish taxa on the dives, together with three species of Scleractinia ( Lophelia pertusa, Madrepora oculata and Desmophyllum cristagalli) and a diverse range of other corals (Antipatharia, Alcyonacea, and Stylasteridae). Stands of live coral provided the only habitat in which Guttigadus latifrons was observed whereas Neocyttus helgae was found predominantly on structural habitats provided by dead coral. Significantly more fish were found on structurally complex coral rubble habitats than on flatter areas where coral rubble was clogged with sand. The most common species recorded was Lepidion eques (2136 individuals), which always occurred a few cm above bottom and was significantly more active on the reefs than on sedimentary habitats. Synaphobranchus kaupii (1157 indiv.) , N. helgae (198 indiv.) and Micromesistius poutassou (116 indiv.) were also common; S. kaupii did not exhibit habitat-related differences in behaviour, whilst N. helgae was more active over the reefs and other structured habitats whereas M. poutassou was more active with decreasing habitat complexity. Trawl damage and abandoned fishing gear was observed at both sites. We conclude that Irish coral reefs provide complex habitats that are home to a diverse assemblage of fish utilising the range of niches occurring both above and within the reef structure.

Loss of Structural Complexity in Staghorn Coral Rubble Habitats Influences the Density of Damselfish in Dry Tortugas National Park, Florida, USA

Loss of Structural Complexity in Staghorn Coral Rubble Habitats Influences the Density of Damselfish in Dry Tortugas National Park, Florida, USA

Commensalism between Juvenile Cusk Eels and Pancake Urchins on Western North Atlantic Seamounts

We describe a commensal relationship between small (approximately 6 to 9 cm) deep-sea cusk eels, one tentatively identified as Barathrites sp. (Osteichthyes: Ophidiidae), and pancake urchins, both Hygrosoma petersi and Phorosoma placenta (Echinodermata: Echinothuriidae). These interactions were observed in situ using a remotely operated vehicle (ROV), deployed at depths of 1410 to 1775 m on three seamounts in the western North Atlantic (Bear and Rehoboth seamounts in the New England Seamounts and Yakutat Seamount in the Corner Rise Seamounts). Full motion video and still frames documented individual cusk eels associated with urchins in open fine-grained sediment and coral rubble habitats. Cusk eels foraged around the periphery of urchins and took refuge at the base and among the long spines on the aboral surface. We suggest that such associations provide juvenile cusk eels with shelter from predators or flow (or both) and access to prey far from other forms of refugia.

New sciophilous sponges from the Caribbean (Porifera: Demospongiae)

Thirteen new species of sponges are described from coral reefs of the Netherlands Antilles and the Colombian Caribbean. Species were collected during quantitative investigations of reef sponges performed by students of the University of Amsterdam in the period between 1984 and 1991. Most of the reported specimens were taken from undersides of coral rubble, crevices or reef caves (sciophilous habitats) and without exception are small encrusting or fistular sponges. The material reported in this paper includes a new genus and species of Placospongiidae, Placospherastra antillensis n. g. n. sp. , the first Caribbean representatives of the genera Triptolemma (Pachastrellidae) and Megaciella (Acarnidae), viz. Triptolemma endolithicum n. sp. and Megaciella incrustans n. sp., a new species of Timeidae, Timea curacaoensis n. sp., a new species of Microcionidae with peculiar colloscleres, Clathria (Thalysias) collosclera n. sp., two new species of Chondropsidae, viz. Batzella fusca n. sp., and Strongylacidon unguiferum n. sp., three new species of Coelosphaeridae, viz. Forcepia (Forcepia) minima n. sp., Forcepia (Forcepia) fistulosa n. sp., and Forcepia (Leptolabis) microlabis n. sp., a new species of Crellidae, Crella (Grayella) beglingerae n. sp., a new species of Hymedesmiidae, Hymedesmia (Hymedesmia) bonairensis n. sp., and a new species of Mycalidae, Mycale (Paresperella) vitellina n. sp. Most species are represented by only small fragments removed from the substrate by scalpel or diving knife, leaving little and often crumbled preserved type material. This study is intended to demonstrate that the small crusts dominating easily accessible shallow water coral rubble habitats in the Caribbean remain understudied.

Colonization patterns of mobile cryptic animals into interstices of coral rubble

Coral rubble is one of the characteristic bottom habitats in tropical and subtropical coral reefs. Many mobile organisms inhabit the interstices among coral rubble. Because coral rubble habi- tats are frequently subjected to physical disturbances, the process of assemblage recolonization is important for maintaining the diversity and productivity in coral reefs. The present study examined the colonization patterns of these mobile organisms by using experimental traps with defaunated coral rubble at 3 areas (Back reef, Seagrass bed, and Nearshore) in a fringing coral reef on Ishigaki Island, Japan. Sixteen mesh trays filled with coral rubble were set at each of the 3 areas; 4 trays were collected after 1, 2, 4, and 8 wk. The experiment was repeated in winter and spring. The number of species that occurred in the trays generally increased with the time period, but detailed examination was difficult because of significant interaction factors. Higher order interactions (season, area, and time period) were also significant for variations in assemblage composition. Temporal and spatial variations in abundances of 15 numerically dominant species (gastropods and decapods) were analyzed by a general linear model with an Akaike's information criterion model selection. Although the patterns of colonization were species specific, initial (<1 wk) and time-dependent (2 to 8 wk) patterns were recognized. These results suggest that a short-distance movement within the local area is the main pathway for the colonization into a disturbed coral rubble habitat. Although seasonal variability in colonization requires consideration, the method using traps with coral rubble provides a standard habitat for quantitative assessment of the assemblage composition of cryptic organisms in coral reefs.

Deep‐water chaunacid and lophiid anglerfishes (Pisces: Lophiiformes) off the south‐eastern United States

Recent research cruises to deep (80–910 m) reef habitats off the south‐eastern U.S. and in the northern Gulf of Mexico have provided new information on the diagnostic characteristics, behaviours, colour patterns in life, bottom associations, distributions and maximum sizes of species of the anglerfish genera Chaunax, Lophiodes and Sladenia. Chaunax stigmaeus occurred much further south than previously known (Blake Plateau off South Carolina), and all C. stigmaeus observed were found associated with dense beds of dead coral (Lophelia pertusa) rubble or on broken hard bottom. In contrast, Chaunax suttkusi was found on soft bottoms. Chaunax stigmaeus and C. suttkusi appear to be sympatric over a major portion of their ranges. Because knowledge of pigmentation in live or freshly caught Chaunax is critical to distinguish some members of the genus, changes in the colouration of C. suttkusi were noted and documented photographically immediately after death and after fixation. The yellow spots found on some, but not all specimens, temporarily disappeared completely after death, but they reappeared after fixation, slowly disappearing thereafter along with other carotenoid pigments. Lophiodes beroe and Lophiodes monodi were collected for the first time off the Atlantic coast of the U.S., being previously known only from the Gulf of Mexico, Caribbean Sea and the northern coast of South America. For both species (L. beroe and L. monodi), the collections included the two largest known representatives of the species (400 and 325 mm standard length, respectively). Lophiodes beroe commonly occurred on L. pertusa rubble, and seemed to prefer this habitat. Occupying such a habitat that is deep and difficult to sample probably explains how this common species escaped detection. Only a single L. monodi was collected or observed, so this species appears to be uncommon in this geographic area or at least so on coral rubble habitat. Detailed aspects of the colour patterns of both species were noted. In particular, L. beroe displayed a characteristic pattern of white patches in life that were not apparent after death. The first photographic documentation of the colour pattern in life and of the pharyngeal pigmentation of Lophiodes reticulatus is provided. The third known specimen of Sladenia shaefersi, and the first to be taken in U.S. waters was collected from coral rubble near the base of a steep 200 m scarp on the Blake Plateau.

Identification of nursery habitats for commercially valuable humphead wrasse Cheilinus undulatus and large groupers (Pisces: Serranidae) in Palau

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 332:189-199 (2007) - doi:10.3354/meps332189 Identification of nursery habitats for commercially valuable humphead wrasse Cheilinus undulatus and large groupers (Pisces: Serranidae) in Palau Mark Tupper1,2,* 1The WorldFish Center, PO Box 500 GPO, 10670 Penang, Malaysia 2Marine Lab, University of Guam, UOG Station, Mangilao, Guam 96923, USA *Email: m.tupper@cgiar.org ABSTRACT: In recent years there has been increasing interest in conserving fish habitats. However, fish–habitat associations, particularly nursery habitat for early juvenile stages, are poorly known for most reef fishes. Using mark–recapture techniques, I examined among-habitat variation in settlement, post-settlement growth, and persistence, and movement in 3 large, vulnerable, and commercially important reef fishes: the humphead wrasse Cheilinus undulatus, the squaretail coralgrouper Plectropomus areolatus, and the camouflage grouper Epinephelus polyphekadion. Both the humphead wrasse and the coralgrouper appeared to utilize specific nursery habitats. Settlement, growth, and persistence of humphead wrasse were highest in branching coral structures mixed with bushy macroalgae (BCMA). Of all tagged C. undulatus recaptured in intermediate or adult habitats, 80% were tagged post-settlement in BCMA. Early juvenile P. areolatus were found almost exclusively in coral rubble habitats on the slopes of tidal channels, at a narrow depth range of 5 to 7 m. This dependence on one habitat type could render this species vulnerable to shipping or dredging operations or other forms of coastal development. E. polyphekadion appeared to be a habitat generalist, and no specific nursery habitat could be identified. In summary, spatial management (e.g. implementation of marine protected areas) should prioritize habitats for conservation according to their value as essential nursery or spawning habitats for target species needing protection. KEY WORDS: Fish habitat · Nursery areas · Grouper · Humphead wrasse Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 332. Online publication date: March 05, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Interactions between ophiuroids and beaugregory damselfish

The interactions between beaugregory damselfish and ophiuroids, potential damselfish egg predators, were investigated using several field studies. A survey of back reef areas showed that the two most common ophiuroid species, Ophiocoma echinata and Ophioderma appressum, were significantly associated with the territories of beaugregory males within the coral rubble habitat where both ophiuroids and beaugregory's can be found. Feeding experiments showed that three ophiuroid species (Ophiocoma echinata, Ophioderma appressum and Ophiocoma wendtii) and Echinometra viridis consumed late development stage beaugregory eggs, whereas earlier stages were only consumed by Ophioderma appressum and Echinometra viridis. Manipulation of ophiuroid densities had no significant effect on the survival of beaugregory eggs and had no measurable impact on female mate choice. The aggressive response of male beaugregory damselfish towards three ophiuroid and one echinoid species showed significant differences among species but were lower than those shown to bluehead wrasse, Thallasoma bifasciatum; the principal daylight predator of eggs. The intensity of attacks by male beaugregory damselfish towards Thallasoma bifasciatum increased significantly if males were guarding eggs, but did not appear to change for the four echinoderm species. Male habitat selection was shown to be unaffected by the presence of ophiuroids.

Movement Patterns, Habitat Utilization, Home Range Size and Site Fidelity of Whitesaddle Goatfish, Parupeneus Porphyreus, In a Marine Reserve

Suitability of small (< 1 km2) marine reserves for protecting a commercially important endemic Hawaiian goatfish, Parupeneus porphyreus, was examined by quantifying goatfish habitat use, home range size and site fidelity in an existing marine reserve (Coconut Island in Kaneohe Bay, Hawaii). Five goatfish equipped with acoustic transmitters were tracked for up to 93 h each over 3–14 days. Daytime habitat use patterns of two of these fish were continuously monitored for one month using a fixed hydrophone hardwired to an onshore computer. Acoustically tagged fish showed consistent diel patterns of behavior, refuging in holes in the reef by day and moving over extensive areas of sand and coral rubble habitat at night. Remote monitoring of daytime habitat use by two goatfish revealed that the same daytime refuge was used by both fish for at least one month (the battery life of the transmitters). Home ranges of all fish were within the boundaries of the Coconut Island reserve suggesting that even small areas containing suitable habitat can make effective reserves for this species. A relatively low abundance of reproductive size P. porphyreus at Coconut Island in comparison with deeper areas may indicate an ontogenetic shift to deeper habitat in this species.

Settlement strategies and distribution patterns of coral-reef fishes

Patterns of habitat use established at settlement may be a primary determinant of the distribution of coral-reef fishes within and among habitats. However, due to the difficulty of observing fish larvae in the wild, the behaviour of individuals at settlement has rarely been observed. Here, we examined the behaviour at settlement of five species of damselfishes (family Pomacentridae) by conducting multi-choice experiments in large outdoor aquaria at Lizard Island on the Great Barrier Reef, Australia. Late-stage larvae that were competent to settle were collected using light traps and placed in large circular aquaria at night where they could choose to settle among live coral, dead branching coral, coral rubble and bare sand habitats. We examined patterns of habitat choice at settlement by larvae with no prior experience of the reef (naive larvae). The effect of experience in the reef environment on habitat preferences was then determined by studying the behaviour of juveniles collected soon after settlement and exposed to the same experimental protocol. We also examined the importance of interspecific interactions among late-stage larvae and interactions between newly settled juveniles and adults in determining patterns of habitat choice exhibited by larvae and newly settled juveniles. Late-stage larvae and newly settled juveniles made distinct habitat choices but the choices made varied widely among species. Chromis viridis (Cuvier) late-stage larvae selected live coral and always settled as a group. Post-settlement C. viridis also selected live coral but exhibited stronger schooling behaviour and moved around the aquaria more frequently than late-stage larvae. Pomacentrus moluccensis (Bleeker) consistently selected live coral and also preferentially selected habitats where conspecifics, either settlers or adults, were present. P. amboinensis (Bleeker) late-stage larvae preferentially selected both live and dead standing coral habitats but avoided coral rubble. Post-settlement P. amboinensis selected live coral more frequently than late-stage larvae. P. coelestis (Jordan and Starks) late-stage larvae initially settled with equal frequency among the habitats presented but exhibited an increasing use of coral rubble and dead coral throughout the day. In contrast, early post-settlers always selected the coral rubble habitat with significantly greater frequency than other habitats. Therefore, experience on the reef may be associated with habitat preferences in P. coelestis. P. chrysurus settlers were distributed evenly among habitats due to agonistic interactions among individuals observed within hours of settling. Also, early post-settlement P. chrysurus avoided habitats containing adults. For the pomacentrids we tested, the patterns of habitat selection observed in our experiments were similar to the distribution of adults among habitats on the reef at Lizard Island. Also, interactions among individuals at settlement could explain the spacing of individuals within habitats. Therefore, precise selection of habitats at settlement and behaviour among conspecifics within hours of settling may have a major influence on the distribution of coral-reef fishes within and among habitats.