Octocoral Carijoa Riisei Research Articles

UPDATED DISTRIBUTION OF OCTOCORAL Carijoa riisei (DUCHASSAING & MICHELOTTI, 1860) IN BRAZIL INCLUDING ITS FIRST RECORD IN THE STATE OF SERGIPE, NORTHEASTERN BRAZIL

This study recorded, for the first time, the presence of the azooxanthellate colonial octocoral Carijoa riisei (Carijoidae) in the state of Sergipe, Brazil. In September 2021, colonies of C. riisei were observed attached to a floating pier in the estuary of the Vaza-Barris River, in the central region of the Sergipe coastline. These colonies were photographed in situ and collected for confirmation of their morphological identification in the laboratory. Our results represent the first recorded occurrence of Carijoa riisei in the state of Sergipe and contribute to filling a gap in the species distribution along the Brazilian coast. Future studies are necessary to assess the potential impacts of C. riisei on local ecosystems and understand the role of artificial substrates in the dispersal of invasive species.

Reproduction of Carijoa riisei (Cnidaria: Octocorallia) in the Panamanian tropical eastern Pacific

Octocorals are the main component of rocky walls in the Panamanian tropical eastern Pacific (TEP), providing shelter and substrate for diverse marine invertebrates and demersal fishes. Despite their ecological importance, many essential biological traits of these corals remain undescribed. Like some cnidarians, octocorals may be related to bioinvasion. One emerging risk is the rise of the Indo-Pacific invasive octocoral Carijoa riisei, which overgrows other soft corals, competing for food and space and promoting the emergence of diseases. Considering the potential risk to native octocorals, we investigated the reproductive seasonality of C. riisei at 15 m depth every month for one year in the Gulf of Panama (Las Perlas Archipelago), an octocoral diversity hotspot with seasonal upwelling. Carijoa riisei showed an average fecundity (percentage of polyps with eggs sampled throughout the year from only female colonies) of 53% (SE 0.03%) with no seasonality. Carijoa riisei produced eggs continuously with overlapping generations, with an average of 23 (1–107; SE 0.75) eggs per fertile polyp and an average egg diameter of 0.12 (0.10–0.64; SE 0.0008) mm. The number of eggs inside the gastrovascular cavity was higher during the upwelling. However, the size and proportion of large eggs were greater towards the end of the upwelling season, with a drastic decrease from 30% to 2% at its end. Our results over a one-year sampling period show that in the Panamanian TEP, C. riisei reproduces continuously, seemingly energized by higher nutrient levels present during upwelling. This, along with its rapid growth rate, makes this species a formidable competitor for native species. Thus, we encourage future monitoring of these populations.

The alien octocoral Carijoa riisei is a biogenic substrate multiplier in artificial Brazilian shipwrecks.

Despite the obvious negative effects caused by invasive species, some recent studies have shown that the impacts at local scale are diverse and not necessarily negative. Arborescent benthic organisms such as octocorals form three-dimensional structures capable of increasing the amount of substrate available and providing shelter for epibiont species. We investigated the role of the alien octocoral Carijoa riisei on the diversity of benthic communities in three shipwrecks on the north-eastern coast of Brazil. We expected that (a) the fauna associated with the octocoral are richer and more diverse compared to the adjacent; (b) some species are exclusively associated with C. riisei; (c) the species that are present both in the areas with and without C. riisei have a greater abundance when associated with the octocoral. For this, we compared the macrobenthic communities associated with C. riisei to those found in adjacent areas where the octocoral was absent. Our study showed that the communities associated with the octocoral were 1.5 times richer and 10 times more abundant than adjacent communities, with 29 exclusive taxa. The dominant taxa were the amphipods Ericthonius brasiliensis and Podocerus brasiliensis and polychaetes of the family Syllidae. These taxa were present in areas with presence and absence of C. riisei, but their abundance was significantly greater where the octocoral was present. Our results reinforce the idea that Carijoa riisei acts as an ecosystem engineer in coastal reefs, creating new habitats and increasing diversity at a local scale, even though it is an alien species.

Invasion and current distribution of the octocoral Carijoa riisei (Duchassaing & Michelotti, 1860) in the Ecuadorian coast (Eastern Tropical Pacific)

Invasion and current distribution of the octocoral Carijoa riisei (Duchassaing & Michelotti, 1860) in the Ecuadorian coast (Eastern Tropical Pacific)

Taking a detour: invasion of an octocoral into the Tropical Eastern Pacific

The tropical snowflake octocoral Carijoa riisei, which is thought to be native to the Indo-Pacific biogeographical region, has been increasingly reported from the Colombian Tropical Eastern Pacific (TEP) over the past two decades. Massive mortalities of native octocorals, particularly in Pacifigorgia spp. and Muricea spp., were observed due to C. riisei overgrowth. However, the area of origin of TEP C. riisei remains unknown and its potential invasive status has not been addressed yet. We evaluated geographical scenarios for the colonization of the Colombian TEP by conducting phylogeographical analyses based on nuclear and mitochondrial sequences of 306 individual specimens from across the species’ (native/non-native) range and applying hypothesis-specific operational criteria. Additionally, we assessed whether C. riisei has to be considered an invasive species based on the previously proposed ‘unified framework for biological invasions’. Our results showed relatively high genetic differentiation between Colombian TEP populations, on the one side, and Indo-Pacific and Hawaiian populations, on the other side. In contrast, we could not identify genetic differentiation and significant isolation by distance (IBD) between Colombian TEP and Tropical Atlantic populations. C. riisei might have been introduced from the Atlantic into the Colombian TEP, possibly via the Panama Canal. Based on the criteria of the ‘unified framework for biological invasions’, we also conclude that this octocoral constitutes an invasive species. Our study may serve as a basis for establishing strategies to protect native species from one of the very few invasive coral species worldwide.

Pregnane steroids from the Vietnamese octocoral Carijoa riisei

Six pregnane steroids including one new compound namely 15β-hydroxypregna-4,20-dien-3-one (1), were isolated and structurally elucidated from the octocoral Carijoa riisei. The cytotoxic activity against a panel of eight human cancer cell lines of isolated compounds was also evaluated by SRB method. As the results, 18-acetoxypregna-1,4,20-trien-3-one (5) showed significant cytotoxicity against all the tested cell lines with the IC50 values from 22.29 ± 1.47 to 48.73 ± 3.93 μM, whereas 15β-acetoxypregna-1,4,20-trien-3-one (3) and 20R-acetoxypregna-1,4-dien-3-one (6) only exhibited weak effect on KB cell line with IC50 values of 93.62 ± 7.32 and 71.38 ± 5.45 μM, respectively.

INVERTEBRADOS MARINOS ASOCIADOS CON LAS PLATAFORMAS DE GAS EN LA GUAJIRA (CARIBE COLOMBIANO)*

The industrial and economic development of Colombia has expanded its limits towards the territorial sea in the search for new resources. The prospection and construction of infrastructures in the sea challenge new alternatives for the sustainable development of the country. The main goal of this study was to build a baseline inventory of the marine invertebrates associated to two gas platforms located offshore in La Guajira, at the northeastern Colombian Caribbean Sea: platforms A and B, sitting on sandy bottoms at 18 and 33 m depth, respectively. This inventory includes a total of 116 species of marine invertebrates that were collected by Scuba diving. Crustaceans had the greatest richness with 50 species, from which the infraorder Brachyura was the best represented with 10 families including approximately 44% of species. Mollusks comprised the second largest group with 29 species, followed by annelids with 14 species, sponges with 12 species, cnidarians with 7 species, and finally echinoderms with 4 species. Filter-feeding and sessile organisms dominated in abundance, while mobile species showed a larger number of species. The barnacles complex (Balanus spp.), the octocoral Carijoa riisei and sponges were the main components of the fouling fauna on the structures. Although there are no previous studies for the study area and the southern Caribbean, it is considered that the invertebrates community associated to gas platforms in La Guajira exhibit both high species richness and a large abundance of organisms.

New invertebrate host records (Porifera and Cnidaria) for some caridean shrimps in estuaries of north-eastern Brazil

We report for the first time the association of some caridean shrimps with the octocoral Carijoa riisei (Cnidaria: Clavulariidae) and the sponge Dragmacidon reticulatum (Porifera: Axinellidae), in estuaries from north-eastern Brazil. The alpheid shrimp Synalpheus apioceros , Synalpheus fritzmuelleri , Alpheus formosus , Alpheus carlae and the palaemonid Cuapetes americanus are reported in association with Carijoa riisei . The latter two species, plus the alpheid Alpheus buckupi, are recorded in association with D. reticulatum.

Comparisons of sexual reproduction in Carijoa riisei (Cnidaria, Alcyonacea) in South Atlantic, Caribbean, and Pacific areas

Soft corals show a wide variety of reproductive strategies, including both asexual and sexual reproduction which can influence macro-evolutionary processes. The octocoral Carijoa riisei has an ample geographical distribution in Pacific and southern Atlantic and also in Caribbean region. This species was considered invasive in Hawaii, and its capacity for rapid proliferation is recognized, but recent studies, however, have indicated that it appears to be native to the Indo-Pacific region. The present study examined the reproductive biology of C. riisei in the Atlantic basin. The results were then compared to previous studies of the same species from the Pacific (Hawaii) and Caribbean (Puerto Rico) regions to examine the hypothesis that the reproductive patterns of C. riisei populations are the same throughout its geographical distribution, independent of its native or non-native status. Samples were collected on a monthly basis from May/2007 to April/2008 at Porto de Galinhas (Pernambuco State, Brazil). This species was found to have similar reproduction patterns in Brazil, the Caribbean, and in Hawaii (a gonochoric reproductive pattern and continuous and asynchronous gamete release). The similarities of their traits contribute to its rapid proliferation and occupation of spaces left by other species, independent of its native or non-native status.

Prey selectivity of the octocoral Carijoa riisei at Pernambuco, Brazil

This study was designed to evaluate prey selection (type and size) by the octocoral Carijoa riisei at Porto de Galinhas beach, Northeast Brazil, relating prey availability in plankton with the content inside polyps. Diatoms and cyanophytes were the predominant items found in both polyp gastric cavity and plankton. A correlation between prey abundance in the plankton and in the gastric cavity of C. riisei polyps was observed. Mastogloia sp. showed the highest positive electivity index (0.99). Benthonic items were found, with 0.51% of total consumed preys. The size amplitude of prey items in the plankton was similar to those found inside the polyps, although the mean prey size in the polyps (112.7 µm) was significantly lower than the value found in the plankton (240.5 µm). Thus, the study indicates some size selectivity in this species or at least size limitation. From the results, we concluded that the octocoral C. riisei is an opportunistic polyphagous species in the Brazilian northeast coast, showing suspensivorous passive filtering feeding habit with a preference for small prey items and evidencing its important ecological role in the reefal ecosystem as responsible for bidirectional energy transference between pelagic zones and the benthos.

Prey selectivity of the octocoral Carijoa riisei at Pernambuco, Brazil

This study was designed to evaluate prey selection (type and size) by the octocoral Carijoa riisei at Porto de Galinhas beach, Northeast Brazil, relating prey availability in plankton with the content inside polyps. Diatoms and cyanophytes were the predominant items found in both polyp gastric cavity and plankton. A correlation between prey abundance in the plankton and in the gastric cavity of C. riisei polyps was observed. Mastogloia sp. showed the highest positive electivity index (0.99). Benthonic items were found, with 0.51% of total consumed preys. The size amplitude of prey items in the plankton was similar to those found inside the polyps, although the mean prey size in the polyps (112.7 µm) was significantly lower than the value found in the plankton (240.5 µm). Thus, the study indicates some size selectivity in this species or at least size limitation. From the results, we concluded that the octocoral C. riisei is an opportunistic polyphagous species in the Brazilian northeast coast, showing suspensivorous passive filtering feeding habit with a preference for small prey items and evidencing its important ecological role in the reefal ecosystem as responsible for bidirectional energy transference between pelagic zones and the benthos.

Antiprotozoan activity of Brazilian marine cnidarian extracts and of a modified steroid from the octocoral Carijoa riisei

In the present investigation, we have evaluated the antileishmanial and antitrypanosomal activity of methanolic crude extracts obtained from eight species of cnidarians and of a modified steroid isolated from the octocoral Carijoa riisei. The antileishmanial activity of cnidarians crude extracts showed 50% inhibitory concentration (IC50) values in the concentration range between 2.8 and 93.3 microg/mL. Trypomastigotes of Trypanosoma cruzi were less susceptible to the crude extracts, with IC50 values in the concentration range between 40.9 and 117.9 microg/mL. The steroid (18-acetoxipregna-1,4,20-trien-3-one) displayed a strong antileishmanial activity, with an IC50 value of 5.5 microg/mL against promastigotes and 16.88 microg/mL against intracellular amastigotes. The steroid also displayed mammalian cytotoxicity (IC50 of 10.6 microg/mL), but no hemolytic activity was observed at the highest concentration of 12.5 microg/mL. The antileishmanial effect of the steroid in macrophages suggested other mechanism than macrophage activation, as no upregulation of nitric oxide was observed. The antitrypanosomal activity of the steroid resulted in an IC50 value of 50.5 microg/mL. These results indicate the potential of cnidarian natural compounds as antileishmanial drug candidates.

Trophic ecology of the octocoral Carijoa riisei from littoral of Pernambuco, Brazil. I. Composition and spatio-temporal variation of the diet

Octocorals are common components of sublittoral benthic communities in temperate, tropical and polar areas. However, their natural diets and feeding rates are poorly known. The aim of this study was to determine qualitatively–quantitatively the diet of the octocoral Carijoa riisei (snowflake coral) and analyse the distribution and diet composition throughout a whole year at two different depths of the same environment. Hence, 30 colonies were haphazardly sampled for gastric content analysis from 2 and 6 m deep (surface and bottom) at Porto de Galinhas beach, Pernambuco, Brazil, in January, June and October 2006, and March 2007. Relative and absolute abundance, richness and occurrence frequency per gastric cavity were assessed. Shannon–Wiener index (H′) and evenness were also calculated. Items were classified according to the occurrence frequency. The biovolume of preys was estimated from meristic data, and from the biovolume were then estimated wet weight, dry weight and organic carbon. Weighed biovolume (WBV), which relates biomass and abundance, was assessed to estimate the real contribution of preys to octocoral diet. Results attested the presence of 102 phytoplankton and 25 zooplankton taxa. Mean prey size was 112.7 µm. Diatoms showed the greater richness with 88 morphotypes. Only cyanophytes and diatoms, from phytoplankton, were very common (>70%). As a whole, phytoplankton was also the most abundant group (83%), followed by crustacean fragments (5%). Thus, although having low biovolume (<0.09 mm3×10−3), the phytoplankton showed the highest WBV (44.5%). Feeding items richness was homogeneous throughout the study year and in both depths, while abundance showed significant seasonal and bathymetric fluctuation. The t-test (Hutchinson) found significant differences for prey item diversity related to depth and season. From the analysis, it is possible to conclude that the C. riisei population of the Brazilian north-eastern coast is polyphagous, but shows preference for phytoplanktonic elements and small prey. Therefore, the species behaves as a passive suspensivorous feeder with equitable biomass contribution from phytoplankton and zooplankton.

Brittle stars (Echinodermata: Ophiuroidea) associated with the octocoral Carijoa riisei (Cnidaria: Anthozoa) from the littoral of Pernambuco, Brazil

The present work records for the first time the association between ophiuroids and the octocoral Carijoa riisei. Carijoa riisei is a colonial octocoral very abundant in the littoral of Pernambuco (Brazil), with growth by creeping stolons with an arborescent structure creating an optimal environment for epibionts. The objectives of the work were to identify the species of Ophiuroidea associated with C. riisei, and to verify the existence of seasonality through the density, abundance and frequency of sampled taxa. Due to the known relationship between the ophiuroids and sponges related in the literature, the sponges founded associated with C. riisei were recorded. Seasonal samples of the beaches of Porto de Galinhas and Guadalupe were realized. In Guadalupe, 39 and 21 ophiuroids (dry and rainy seasons respectively) belonging to the families Ophiactidae (Ophiactis savignyi, Ophiactis lymani) and Ophiotrichidae (Ophiotrhix angulata) were identified. Ophiactis savignyi stood out in all the analysed stations (48.72% in dry season and 52.38% in rainy season). The average density of the ophiuroids was 10.74 ind/100 g of C. riisei, varying from 12.56 ind/100 g in the dry season to 8.92 ind/100 g, in the rainy season. Amongst the species of ophiuroids recorded in the samples, O. savignyi showed 80% and 100% frequency of occurrence in the dry and the rainy seasons, respectively, and O. lymani showed 80% during the dry season. The presence of O. lymani in Guadalupe constitutes the first record in Pernambuco state. Taking into account that all the ophiuroids collected in Guadalupe were considered juveniles (1–3 mm of disc diameter), the microhabitat created by C. riisei may be utilized as a recruitment place for some ophiuroids. No ophiuroids were found at Porto de Galinhas beach, just as for sponges. On the other hand, the ophiuroids were always found with sponges in Guadalupe beach. For this reason, the ecological relation of the ophiuroids with C. riisei could be observed as an occasional relation, in the way that the octocoral supplies a support structure to the growth of the many sponges that have given a favourable habitat to shelter ophiuroids.

Isolamento e atividades biológicas de produtos naturais das esponjas monanchora arbuscula, aplysina sp. petromica ciocalyptoides e topsentia ophiraphidites, da ascídia didemnum ligulum e do octocoral carijoa riisei

The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60.

Vertical zonation of megabenthic taxa on a deep photosynthetic reef (50–140 m) in the Au’au Channel, Hawaii

This study surveyed several locations at depths between 50 and 140 m within the Au’au Channel, Hawaii to characterize the deep reef habitat and determine the depth distribution and relative abundance of the dominant, habitat forming megabenthic taxa. In the Au’au Channel, the depth distribution of megabenthic taxa exhibited a pattern of vertical zonation with relatively few taxa dominating each zone. Macroalgae particularly Halimeda spp. and to a lesser extent scleractinian corals Leptoseris spp. were dominant between 50 and 80 m; Leptoseris spp. were dominant between 80 and 90 m as macroalgae decreased in abundance; the invasive octocoral Carijoa riisei was dominant between 90 and 100 m primarily on rugose features; Antipathes spp. and Leptoseris spp. were dominant between 100 and 120 m on exposed fossil reef; and small wire corals were dominant between 120 and 140 m. In general, the percentage of live benthic cover decreased with depth, particularly below 90 m where a large majority of the area was uncolonized, soft substrata. The gradient of downwelling light intensity appears to play a major role in regulating the depth distribution of photosynthetic organisms, skilophilous organisms, and other benthic fauna, which compete for space with dominant photosynthetic species. The depth of the seasonal thermocline also appears to play an important role in limiting the distribution of tropical benthic species.

New report of nudibranch predators of the invasive octocoral Carijoa riisei in the Main Hawaiian Islands

New report of nudibranch predators of the invasive octocoral Carijoa riisei in the Main Hawaiian Islands

Dispersal and association of two alien species in the Indonesian coral reefs: the octocoral Carijoa riisei and the demosponge Desmapsamma anchorata

The discovery of the association between the sponge Desmapsamma anchorata (Demospongiae: Poecilosclerida: Desmacididae) and the octocoral Carijoa riisei (Cnidaria: Alcyonacea: Clavularidae) on an Indonesian reef enlarges the widespread dispersion of these Atlantic species in the Indo-Pacific area. The species involved and their morphological adaptations resulting from the association are described. When covered by the sponge, C. riisei develops an irregular branching pattern and a dense nematocyst layer where the ectoderm comes in contact with the sponge tissue. The finding of fertile colonies suggests that the Indonesian population of C. riisei is self-sustaining.