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A biodiversity survey on three corallivorous snails (Mollusca: Gastropoda) was performed at 28 sites around the island of Bonaire to assess their distribution patterns and associated host corals. The snails and their hosts were identified and counted in three depth zones: 5–10, 10–20, and 20–30 m. The snails were Coralliophila galea and C. salebrosa (Muricidae: Coralliophilinae), and Cyphoma gibbosum (Ovulidae: Simniinae). All three species were widespread around the island without apparent interspecific geographical variation. Coralliophila galea was found exclusively on scleractinian corals, Coralliophila salebrosa almost exclusively on octocorals, and Cyphoma gibbosum only on octocorals. Coralliophila salebrosa showed more dietary overlap with Cyphoma gibbosum than with Coralliophila galea. Coralliophila galea was the most commonly encountered species with the largest number of host species. Owing to its hosts distribution, this species also showed a greater maximum depth and a wider bathymetrical range than the other two snails. The other two snails were shallower and their depth ranges did not differ significantly. Host-coral size did not seem to have influence on the number of snails per host. Coral damage caused by the snails was visible but appeared to be low, causing no mortality in Bonaire, which suggests that the relation with their hosts is more parasitic than predatory. Because these three corallivores have occasionally been reported to occur as outbreaks in other Caribbean localities and may act as vectors in the dispersal of coral diseases, it is recommended that future studies should focus on their population dynamics. [ABSTRACT FROM AUTHOR]

Abstract Background Impacts of biotic stressors, such as consumers, on coral microbiomes have gained attention as corals decline worldwide. Corallivore feeding can alter coral microbiomes in ways that contribute to dysbiosis, but feeding strategies are diverse – complicating generalizations about the nature of consumer impacts on coral microbiomes. Results In field experiments, feeding by Coralliophila violacea, a parasitic snail that suppresses coral growth, altered the microbiome of its host, Porites cylindrica, but these impacts were spatially constrained. Alterations in microbial community composition and variability were largely restricted to snail feeding scars; basal or distal areas ~ 1.5 cm or 6–8 cm away, respectively, were largely unaltered. Feeding scars were enriched in taxa common to stressed corals (e.g. Flavobacteriaceae, Rhodobacteraceae) and depauperate in putative beneficial symbionts (e.g. Endozoicomonadaceae) compared to locations that lacked feeding. Conclusions Previous studies that assessed consumer impacts on coral microbiomes suggested that feeding disrupts microbial communities, potentially leading to dysbiosis, but those studies involved mobile corallivores that move across and among numerous individual hosts. Sedentary parasites like C. violacea that spend long intervals with individual hosts and are dependent on hosts for food and shelter may minimize damage to host microbiomes to assure continued host health and thus exploitation. More mobile consumers that forage across numerous hosts should not experience these constraints. Thus, stability or disruption of microbiomes on attacked corals may vary based on the foraging strategy of coral consumers.

A biodiversity survey on three corallivorous snails (Mollusca: Gastropoda) was performed at 28 sites around the island of Bonaire to assess their distribution patterns and associated host corals. The snails and their hosts were identified and counted in three depth zones: 5–10, 10–20, and 20–30 m. The snails were Coralliophila galea and C. salebrosa (Muricidae: Coralliophilinae), and Cyphoma gibbosum (Ovulidae: Simniinae). All three species were widespread around the island without apparent interspecific geographical variation. Coralliophila galea was found exclusively on scleractinian corals, Coralliophila salebrosa almost exclusively on octocorals, and Cyphoma gibbosum only on octocorals. Coralliophila salebrosa showed more dietary overlap with Cyphoma gibbosum than with Coralliophila galea. Coralliophila galea was the most commonly encountered species with the largest number of host species. Owing to its hosts distribution, this species also showed a greater maximum depth and a wider bathymetrical range than the other two snails. The other two snails were shallower and their depth ranges did not differ significantly. Host-coral size did not seem to have influence on the number of snails per host. Coral damage caused by the snails was visible but appeared to be low, causing no mortality in Bonaire, which suggests that the relation with their hosts is more parasitic than predatory. Because these three corallivores have occasionally been reported to occur as outbreaks in other Caribbean localities and may act as vectors in the dispersal of coral diseases, it is recommended that future studies should focus on their population dynamics.

Abstract: Loss of larger consumers from stressed ecosystems can lead to trophic release of mid‐level consumers that then impact foundation species, suppressing ecosystem function and resilience. For example, in coral reef ecosystems, outbreaks of coral predators like crown‐of‐thorns sea stars have been associated with fishing pressure and can dramatically impact the composition and persistence of corals. However, the ecological impacts, and consequences for management, of smaller, less obvious corallivores remain inadequately understood. We investigated whether reef state (coral vs. seaweed domination) influenced densities and size frequencies of the corallivorous gastropod Coralliophila violacea on its common host, the coral Porites cylindrica, within three pairs of small Marine Protected Areas (MPAs) and adjacent fished areas in Fiji. C. violacea densities were 5–35 times greater, and their size frequencies more broadly distributed, within seaweed‐dominated fished areas than in adjacent MPAs dominated by corals. Tethering snails (4–9 mm in shell height) in place on their coral hosts indicated that suppression of snails in MPAs was due to predation, apparently by fishes. When tethered on the benthos (where they rarely occur), rather than on their host, mortality of larger snails (15.0–25.0 mm in shell height) was high in all areas, primarily due to hermit crabs killing them and occupying their shells. Because C. violacea is a sessile gastropod that feeds affixed to the base of corals and produces minimal visible damage, it has been considered a “prudent feeder” that minimally impacts its host coral. We assessed this over a 24‐d feeding period in the field. Feeding by individual C. violacea reduced P. cylindrica growth by ~18–43% depending on snail size. Our findings highlight the considerable, but underappreciated, negative impacts of this common corallivore on degraded reefs. As reefs degrade and corals are lost, remaining corals (often species of Porites) may gain the full attention of elevated densities of coral consumers. This will further damage the remaining foundation species, suppressing the resilience of corals and enhancing the resilience of degraded, seaweed‐dominated reefs. [ABSTRACT FROM AUTHOR]

Active coral reef restoration is increasingly applied for local reef management, but remains hampered by biological interactions such as coral predation (corallivory). To determine factors that drive corallivory and develop more ecology-based restoration approaches, coral and corallivore communities were characterized and fish bite mark densities quantified on natural coral colonies and fragments outplanted on small artificial structures. Six study sites were distributed equally among three levels of fisheries management at southern Kenyan reefs (fished < reserve < no-take). Obligate corallivorous fish densities strongly correlated with coral cover regardless of fisheries management level, whereas facultative corallivorous fish (mainly parrotfish) were most abundant in no-take zones. High corallivorous snail densities were associated with low coral diversity and corallivorous sea stars were scarce. Bite mark densities on natural reefs were clearly higher for branching corals, but did not correlate to coral cover, coral diversity or corallivorous fish densities. Compared to natural colonies, predation pressure was up to 24-fold greater on outplanted coral fragments and especially fierce inside no-take zones. This high predation pressure correlated with low live tissue cover of outplanted fragments. These results demonstrate that reefs with low coral cover, often targeted for restoration, do not necessarily experience greater coral predation and that improved outplanting methods and species considerations are needed to address high predation pressure on outplanted fragments. The interplay between fisheries management, reef restoration and corallivory warrants further scrutiny: while obligate corallivorous fish are unlikely detrimental to reef recovery, high densities of facultative corallivorous fish could hamper restoration efforts. • Highest fish bite mark densities on branching coral growth forms. • No 'predation pit': Predation pressure not elevated at reefs with lower coral cover. • Strongest predation on outplanted corals, especially inside no-take zones. • Facultative corallivorous fish most abundant in no-take zones. • Predation marks associated with reduced live tissue cover of outplanted corals. [ABSTRACT FROM AUTHOR]

Disturbances such as tropical storms cause coral mortality and reduce coral cover as a direct result of physical damage. Storms can be one of the most important disturbances in coral reef ecosystems, and it is crucial to understand their long-term impacts on coral populations. The primary objective of this study was to determine trends in disease prevalence and snail predation on damaged and undamaged colonies of the threatened coral species, Acropora palmata, following an episode of heavy ocean swells in the US Virgin Islands (USVI). At three sites on St. Thomas and St. John, colonies of A. palmata were surveyed monthly over one year following a series of large swells in March 2008 that fragmented 30 to 93% of colonies on monitored reefs. Post-disturbance surveys conducted from April 2008 through March 2009 showed that swell-generated damage to A. palmata caused negative indirect effects that compounded the initial direct effects of physical disturbance. During the 12 months after the swell event, white pox disease prevalence was 41% higher for colonies that sustained damage from the swells than for undamaged colonies (df = 207, p = 0.01) with greatest differences in disease prevalence occurring during warm water months. In addition, the corallivorous snail, Coralliophila abbreviata, was 46% more abundant on damaged corals than undamaged corals during the 12 months after the swell event (df = 207, p = 0.006).

Los arrecifes del Parque Nacional Morrocoy (PNM) se encuentran actualmente impactados. Posterior a la mortandad masiva ocurrida en 1996, ha habido indicios de recuperación de Acropora palmata. Este proceso podría ser retrasado por Coralliophila. Se observaron solamente tres colonias de A. palmata en todo un arrecife de Cayo Sombrero. En julio 2005 estas presentaron densidades de Coralliophila abbreviata de 4, 0 y 2 ind/col y de Coralliophila caribaea de 22, 14 y 0 ind/col y, en enero 2006 las densidades fueron: 8, 0 y 4 ind/col de C abbreviata y 22, 14 y 0 ind/col de C caribaea. En las tres colonias se observaron cuatro lesiones (dos de cada depredador). Hubo pérdida de tejido de 66,14 cm a 162,85 cm en las lesiones ocasionadas por C abbreviata, con tasa de depredación de 0,52 cm día-1 en una de ellas, mientras que en otra fue de 37,41 a 72,50 cm con tasa de depredación de 0,19 cm día-1 . Las lesiones generadas por C caribaea no cambiaron. Es probable que el efecto de Coralliophila afecte la recuperación de A. palmata en el PNM, considerando la alta densidad de depredadores y la escasa abundancia de este coral en este parque.The coral reefs of Morrocoy National Park are currently deteriorated. After the massive mortality of 1996, Acropora palmata has shown some signs of recovery, a process that could be hampered by Coralliophila. We observed only three colonies of A. palmata in an entire reef in Cayo Sombrero. In July 2005, these colonies registered Coralliophila abbreviata densities of 4, 0, and 2 ind/col and Coralliophila caribaea densities of 22, 14, and 0 ind/col; in January 2006, said densities were 8, 0, and 4 ind/col (C. abbreviaté) and 22, 14, and 0 ind/col (C. caribaea). Four sites of damage (two per predator) were observed in the three colonies. In one colony, C abbreviata caused a loss of tissue of 66.14 to 162.85 cm , indicating a predation rate of 0.52 cm² day-1. In the other colony, the damage ranged from 37.41 to 72.50 cm2, with a predation rate of 0.19 cm day-1. The areas damaged by C caribaea did not show any change. The high density and predation rate of Coralliophila likely affected the recovery of the scant specimens of A. palmata in Morrocoy National Park.

Acropora palmata populations have experienced steep declines over the past 30 years. Although numerous culprits are recognized, their relative contributions to the decline are poorly quantified, making it difficult to prioritize effective conservation measures. In 2004, a demographic monitoring program was implemented in the Florida Keys (USA), aimed at determining the relative importance of various stressors affecting A. palmata. A subset of randomly selected A. palmata colonies within 15 fore-reef plots was tagged and surveyed three to four times per year over 7 years. Colony size, live tissue, prevalence of disease, snail ( Coralliophila abbreviata) predation, physical damage and other conditions were assessed at each survey. The estimated effect of each condition causing recent mortality was ranked, and together, these parameters were used to attribute the population-level tissue loss associated with each condition. In addition, all new colonies in the study plots were counted and assessed annually in order to track trends in total colony count and live tissue abundance. Between 2004 and 2010, the study population has shown more than 50% decline in live area from three main conditions: fragmentation, disease and snail predation. Approximately half of this decline occurred during the catastrophic 2005 hurricane season from which recovery has been minimal. Meanwhile, colony abundance has shown gradual decline throughout the study. Snail predation was the most prevalent condition. However, it ranked third in attributed tissue loss, behind breakage that occurred during the 2005 hurricane season, and disease. Thermal bleaching of A. palmata was not observed during this study. Because mortality continues to outpace recruitment and growth, intervention to ameliorate losses to the more manageable threats including predation and breakage could result in substantial conservation of live tissue, buying time for the abatement of less tractable threats to A. palmata recovery such as climate change and disease. [ABSTRACT FROM AUTHOR]

The twenty Recent species of the muricid subfamily Coralliophilinae known from the New Zealand region are recorded and illustrated. The following eight species are reported for the first time from New Zealand: Babelomurex nakamigawai (Kuroda, 1959), Coralliophila sp. aff. sertata, C. solutistoma Kuroda & Shikama in Shikama, 1966, Hirtomurex marshalli Oliverio, 2008, Latiaxis pilsbryi Hirase, 1908, Leptoconchus sp., Mipus matsumotoi Kosuge, 1985 and Rhizochilus sp. cf. antipathum Steenstrup, 1850. The species previously recorded as Neothais clathrata (A. Adams, 1854) from New Zealand is actually Coralliophila squamosissima (E.A. Smith, 1876). Two new species are described from bathyal depths: Hirtomurex tangaroa n. sp., and Hirtomurex taranui n. sp. Four species (Coralliophila sertata (Hedley, 1903), C. sp. aff. sertata, Hirtomurex tangaroa n. sp. and H. taranui n. sp.) are restricted to the South-West Pacific, with the latter three possibly endemic to the New Zealand region. All the New Zealand species have planktotrophic development, and 60% of them live in deep water. [ABSTRACT FROM AUTHOR]