Abstract:

The presence of associated endofauna can have an impact on the health of corals. Duringfieldwork on the southern Caribbean island of Curaçao in 2021, the presence of an unknown coral-dwelling worm snail was discovered, which appeared to cause damage to its hosts. A study of photoarchives revealed that the species was already present during earlier surveys at Curaçao since 2014and also in the southern Caribbean island of Bonaire in 2019. It was not found in St. Eustatius, anisland in the eastern Caribbean, during an expedition in 2015. The vermetid snail was preliminarilyidentified asPetaloconchussp. Its habitat choice resembles that ofP. keenae, a West Pacific coralsymbiont. The Caribbean species was observed in 21 host coral species, more than reported for anyother vermetid. BecausePetaloconchussp. is a habitat generalist, it is possible that it was introducedfrom an area with another host-coral fauna. The unknown vermetid is considered to be cryptogenicuntil future studies reveal its actual identity and its native range.

Supplemental Materials.

A B S T R A C T

An increasing number of artificial reefs (ARs) are constructed to compensate for the loss of natural reefs (NRs),
but little is known about their benthic community composition. Here, we compared the densities of coral-
associated fauna (CAF) between a centuries-old manmade structure and the nearest NR at St. Eustatius,
eastern Caribbean. Overall, no significant difference in the density of CAF (coral-dwelling barnacles, crabs,
worms) was found between the NR and the AR, nor between the exposed and sheltered sides of each. Signifi-
cantly different densities of CAF related to host cover were observed among corals on both the AR and the NR.
Per host species, the AR did not show such differences in density between exposed and sheltered sides, although
these differences were observed on the NR. Thus, turbulence and host cover regulate the density of CAF, while
differences also depend on host species composition. Furthermore, from an ecological engineering perspective,
the present AR resembles the NR in overall design, but not in relief rugosity and surface structure, which are also
considered important contributors to the difference in species assemblages of the host corals and their CAF, even
after many decades of community development

Abstract:

There is much documentation about seahorses (Hippocampus spp.) being threatened by habitat degradation and overfishing, but relatively few published studies mention their natural predators. The present study documents three cases in which seahorses are being caught by octopuses. In one case, the seahorse was partly consumed. These observations made at Bonaire (Caribbean Netherlands) and New South Wales (Australia) suggest that predation on seahorses by octopuses may be more widespread and common than previously thought.

Abstract

Marine community datasets are key to the effective management and conservation of marine ecosystems, including coral reefs, which are increasingly threatened by a myriad of stressors. Although community information exists for many comparatively well-studied taxa, other common groups remain to be examined for even such basic information. In this study, we report on the zoantharian communities (Cnidaria: Anthozoa: Hexacorallia: Zoantharia) on the reefs of Bonaire in the southern Caribbean, and compare current results from 30, 20, 10, and 5 m depths to recent similar surveys from nearby Curaçao. The surveys revealed a total of 17 zoantharian species and epibiotic associations on the reefs of Bonaire. Additionally, results showed that while zoantharian assemblages around Bonaire at shallow 5 and 10 m depths, dominated by Palythoa spp., were similar to those found on Curaçao, diversity and numbers of zoantharians were higher at 20 and 30 m due to more abundant epibiotic Parazoanthidae species associated with sponges. Differences in assemblage structure were seen in deeper 20 and 30 m depths between the two islands, implying that conservation of deeper reef slopes, or along depth gradients, may need to be independently considered and addressed for each location. Analyses with environmental parameters on the Bonaire dataset indicate the potential importance of coral reef rugosity and physical structure in shaping these zoantharian communities, aspects that should be focused on in more detail in future research.

Read the full article here: https://link.springer.com/article/10.1007/s00338-022-02226-x

Abstract: A salp swarm was observed in Director’s Bay, Curaçao in July 2021, where salps were caught and consumed by three scleractinian colonial reef corals: Madracis auretenra, Locke, Weil & Coates, 2017; Meandrina meandrites (Linnaeus, 1758), and Montastraea cavernosa (Linnaeus, 1767). The first two scleractinians are newly recorded salpivores. Since the coral polyps were collaborating, predation was not restricted by polyp size. This is the first detailed report on salpivorous corals in the Caribbean

Brachyuran crabs of various families are known as obligate associates of stony corals, with many of these species living as endosymbionts inside the skeleton of their hosts. In particular, coral gall crabs (Cryptochiridae) have been well studied in tropical coral reefs around the world. These crabs can be recognized by the shape of their dwellings (or pits), which may be crescent-shaped or resemble a slit, a canopy, a basket, or a gall, depending on the identity and morphology of their host, and on the position inside the host’s skeleton. Cryptochirids are each known to be associated with a few scleractinian host species (Anthozoa: Scleractinia) or only one. Crabs of the species Latopilumnus tubicolus Türkay and Schuhmacher, 1985 (Pilumnidae), have so far only been reported as endosymbionts of the Indo-Pacific scleractinian Tubastraea micranthus (Ehrenberg, 1834). Their dwellings are unique because they start in one of the coral’s calyces from where they penetrate deep inside the coral branches, becoming long and tubular, whereas the pits (or cysts) of cryptochirids remain relatively shallow.

Article referenced in BioNews 34 article "New discoveries on relationships between host corals, crabs and christmas tree worms"

Caribbean Christmas tree worms (Annelida: Polychaeta: Serpulidae: Spirobranchus) are considered host generalists in their associations with anthozoan (Scleractinia) and hydrozoan (Millepora) stony corals. As planktonic larvae, they settle on coral surfaces and start secreting a calcareous tube to be used as a dwelling. This tube usually becomes overgrown by the host coral (except for its opening) and may get encapsulated deep inside the coral skeleton. In this manner, the well-protected worms grow and survive predation and other hazards, allowing them to live for over four decades. When the host corals are overgrown by other organisms, such as octocorals and sponges, these may act as secondary hosts.

The long lists of Caribbean host species suggest that the recorded number has reached a maximum. However, recent surveys (2015–2019) in the southern and eastern Caribbean, as well as in the Greater Antilles, enabled us to establish new records of two primary hosts (scleractinians) and two secondary hosts (a zoantharian and an ascidian).

Article referenced in BioNews 34 article "New discoveries on relationships between host corals, crabs and christmas tree worms"

Abstract. In contrast with a general decline of Caribbean reef corals, a previously rare sun coral is
increasing in abundance within shallow coral communities on Curacao. This azooxanthellate scleractinian
was identified as Cladopsammia manuelensis, which has an amphi-Atlantic distribution. Over the last decade,
C. manuelensis has increased abundance along the leeward coast of Curacao (southern Caribbean)
between depths of 4 and 30 m. This species was initially not noticed because it resembles the invasive coral
Tubastraea coccinea, which was introduced to Curacao from the Indo-Pacific around 1940. However, in contrast
to T. coccinea, C. manuelensis was previously only present on deeper reef sections (>70 m) of Caribbean
reefs. Our observations illustrate how the sudden increase in abundance of a previously unnoticed, apparently
cryptogenic species could result from natural dynamics on present-day reefs, but also could easily be
mistaken for an invasive species. The finding that deep reef sections can harbor species capable of colonizing
shallower reef zones highlights the importance of thorough inventories of reef communities across
large depth ranges, which can help us to discriminate between range increases of native species and the
arrival of invasives.

Key words: bathymetric distribution; Cladopsammia; coral reefs; cryptogenic; deep water; Dendrophylliidae; invasive;
native; Rhizopsammia; Tubastraea;.