Over 130 years of survival by a small, isolated population of Favia gravida corals at Ascension Island (South Atlantic)

info:eu-repo/semantics/publishedVersio

Rarity in the native range of the Lessepsian migrant <i>Plocamopherus ocellatus</i> (Nudibranchia):Fact or artifact?

The opening of the Suez Canal in 1869 enabled a large number of Indo-Pacific marine species to expand their ranges into the Mediterranean Sea (Galil et al. 2017), entering the Gulf of Suez from the Red Sea and migrating northwards towards the easternmost basin of the Mediterranean. These species have been called 'Lessepsian migrants' (Yonow 2015), 'Lessepsian immigrants' (Kleitou et al. 2019), or 'Lessepsian invaders' (Ivkic et al. 2019), named after Ferdinand de Lesseps who planned the Suez Canal's construction, or 'Erythraean non-indigenous species' (Galil et al. 2017), after the Erythraean Sea, an earlier maritime designation including both the Red Sea and the Gulf of Aden

Abundance of coral-associated fauna in relation to depth and eutrophication along the leeward side of Curaçao, southern Caribbean

Coral-associated invertebrates contribute much to the biodiversity of Caribbean coral reefs. Although the nature of their symbiotic relation is usually not fully understood, they can cause damage to their hosts, especially when they occur in high densities. The abundance of seven groups of coral-associated invertebrates was investigated on reefs along the leeward side of Curaçao, southern Caribbean. In particular, coral barnacles (Pyrgomatidae), boring mussels (Mytilidae: Leiosolenus spp.), gall crabs (Cryptochiridae), and Christmas tree worms (Serpulidae: Spirobranchus spp.) were recorded together with their host corals by means of a photo survey at four depths (5, 10, 15, 20 m) and across seven sites with high and five sites with low eutrophication values (based on δ15N isotope data). Feather duster worms (Sabellidae: Anamobaea), coral blennies (Chaenopsidae: Acanthemblemaria), and worm snails (Vermetidae: Petaloconchus) were insufficiently abundant for thorough quantitative analyses. The results show a decrease in the number of barnacles and Christmas tree worms per host over depth, which could be related to the availability of their host corals. Sites with high δ15N values show a higher abundance of barnacles and Christmas tree worms per host than sites with low values. This indicates that eutrophication could be favourable for these filter feeding organisms but when their densities become too high, they tend to overgrow their hosts and may become a threat to them

A high-latitude, mesophotic Cycloseris field at 85 m depth off Rapa Nui (Easter Island)

Published records of mesophotic zooxanthellate corals from Rapa Nui (Easter Island) are rare and so far based only on dredged specimens and observations during scuba dives (Wells 1972, Glynn et al. 2003, 2007). During recent remotely operated vehicle (ROV) surveys off Rapa Nui (March 2016), a large and dense aggregation of zooxanthellate Cycloseris corals (Scleractinia: Fungiidae) with a density of approximately 500 ind m−2 was discovered (27°08΄55˝S, 109°26΄46˝W) on black sand in a depth range of approximately 79–85 m (Panels A, B). A few corals were overturned, exposing their white (azooxanthellate) undersides and sutures along which self-fragmentation took place (Panel C, arrows). The Cycloseris field was video-recorded on 17 March, 2016, with a high-resolution camera, equipped with two red parallel laser beams for size calibration (see Online Supplementary Video). More than 95% of the corals showed autotomy and regeneration, similar to fields dominated by Cycloseris distorta (Michelin, 1842) in the Galápagos Islands (Feingold 1996, Hickman 2008, Glynn et al. 2018) and by Cycloseris fragilis (Alcock, 1893) in the Persian Gulf (Hoeksema et al. 2018)

Onset of autotomy in an attached Cycloseris coral

(Scleractinia: Fungiidae) are either complete individuals or fragments in various stages of fission and regeneration (Hoeksema and Waheed 2011). Their fragmentation is initiated by a process of radial skeleton dissolution called autotomy (Yamashiro et al. 1989; Yamashiro and Nishihira 1994). Only unattached fragmenting corals are known, representing the adult anthocyathus stage. The anthocaulus stage in which juveniles of free-living species are still attached, as i

Size-dependent dispersal by Goniopora stokesi corals at Semporna, eastern Sabah, Malaysia

Free-living corals of Goniopora stokesi Milne Edwards & Haime, 1851 (Scleractinia: Poritidae) were observed at various sites during the Semporna Marine Ecological Expedition(SMEE 2010) in eastern Sabah, from 29 November to 18 December 2010. At two out of 63 sites, dense aggrega tions (75- 100% cover) with extended polyps had formed only on the sandy bottom of depressions (at 16-20 m depth). These corals could not leave, unlike scattered G. stokesi corals found on sandy slopes, which may migrate in downward direction (Hoeksema 1988). The largest coral patch (Fig. 1a) was c. 200 m2 (Denawan I.) and the other only c. 40 m2 (Larapan I.).Some colonies showed budding through the formation of polyp balls (Fig. 1b), which is a known trait in this species (Boschma 1923; Rosen and Taylor 1969). A few parent individuals had loose polyp balls around them, which had dropped and rolled to available space nearby. Most large specimens were dome-shaped with their dead, fl attened base on the sand or partly buried inside it (Fig. 1b). Only a few were found in upside-down position or laying on a side (Fig. 1c). The heavy weight and fl at underside of these large corals would likely hinder any further migration and may render them practically immobile. Our observations suggest that free-living G. stokesi corals can disperse easily when they are small and may eventually form dense fi elds when they are physically entrapped by the surrounding reef