Three New Species of the Sun Coral Genus Tubastraea (Scleractinia: Dendrophylliidae) from Hong Kong, China.

Tubastraea is a genus of azooxanthellate scleractinian corals belonging to the family Dendrophylliidae, which are commonly called sun corals. This genus currently has only seven recognized species. In this paper, we report three new species of Tubastraea, including T. dendroida sp. nov., which has a tree-like colony, T. violacea sp. nov., which has violet polyps, and T. chloromura sp. nov., which has olive green polyps. These species are distinct in their septal structures, as well as their rDNA sequences including the entire ITS1, 5.8S and ITS2, and a segment of the 18S and 28S genes.

Morphology, Feeding Rate and Larval Settlement Preference of the Corallivorous Nudibranch Phestilla subodiosa (Nudibranchia: Trinchesiidae) from Hong Kong.

We studied the morphology, host specificity, feeding rate and larval settlement preference of the corallivorous nudibranch Phestilla subodiosa collected from the field. These specimens collected from the scleractinian coral Monipora peltiformis in Hong Kong waters are morphologically different from the holotype and paratypes collected from an aquarium culture of Montipora spp., as they have diamond-shaped swollen bulbs, and brown spots on cerata, as well as bulbs and the body immediately posterior to cerata. In experiments where P. subodiosa individuals were placed on the surface of several species of common scleractinian corals collected from Hong Kong waters, the nudibranchs were found to feed on M. peltformis at a rate of 0.05 cm2 individual-1 d-1; however, they were killed and eaten by other tested coral species (Pavnoa decussata, Porites lutea and Duncanopsammia peltata). When cultured in seawater conditioned with M. peltiformis, the veliger larvae required six days to become competent for settlement, and at day 9 could reach a maximum metamorphic rate of 31.1%. At competence, the veliger larvae could be induced to settle, indicating the presence of a larval settlement cue released by the host coral. Other coral species or their conditioned seawater did not induce settlement of the P. subodiosa larvae. Overall, our study expands the distribution record of P. subodiosa, adds this species to the list of corallivorous nudibranchs in Hong Kong waters, provides morphological features that were not included in the original description of this species, reveals the host specificity, and provides the feeding rate of this species. These results contribute to a better understanding of the diversity and potential impact of corallivorous nudibranchs in coral ecosystems.

A new species of the sun coral genus Tubastraea (Scleractinia: Dendrophylliidae) from Hong Kong.

Tubastraea, commonly known as sun coral, is a genus of brightly coloured azooxanthellate corals in the family Dendrophylliidae. The diversity of this genus is low, with only seven recognized species. Herein, we describe Tubastraea megacorallita sp. nov. from Hong Kong based on morphological and molecular analyses. This new species exhibits several characteristics of the genus including being colonial, having a rough texture of corallum and no epitheca. It can be distinguished from its congenerics by bigger corallites, and the Pourtals plan arrangement of its septa. The rDNA gene sequences (consisting of ITS1, 5.8S, ITS2, 18S and 28S) showed 2.455.18% divergence from those of its closest relatives, T. coccinea and T. micranthus.

Prey decline leads to diet shift in the largest population of Indo-Pacific humpback dolphins?

The Pearl River Delta (PRD) region on the southeast coast of China has long been known as a highly productive fishing ground. Since the late 1980s, fishing pressure in the PRD has been intense, which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region, such as the Indo-Pacific humpback dolphin (Sousa chinensis). In this study, we examined 54 stomachs with food remains, collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017. The 6043 identified prey items represent 62 teleost taxa, primarily small estuarine fish, but also larger reef fish. The dolphins appear to be opportunistic foragers, hunting across the water-column, with preference for shoaling and meaty fishes (e.g. Collichthys lucidus IRI% = 38.6%, Johnius belangerii IRI% = 23.1%, Mugil cephalus IRI% = 14.0%). Our findings suggest a dietary shift in recent years, from primarily demersal (as previously reported) to greater intake of neritic and pelagic fish. Dolphin foraging group size has decreased in recent years, which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs. We suggest that these are indicators of declining food resources. Faced with a shortage of preferred prey, humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake, while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.

A New Species of Predatory Nudibranch (Gastropoda: Trinchesiidae) of the Scleractinian Coral Goniopora.

Members of the nudibranch genus Phestilla are common predators of scleractinian corals, but currently this genus has 10 described species only. Here we describe Phestilla goniophaga sp. nov., the first formally named predatory nudibranch species of the stony corals from the genus Goniopora. The new species can be distinguished from its congeneric species by the large number of long cerata (up to 16 rows and 23 cerata per row), and white rounded hump on the notum. The hump resembles the mouth of the coral poly, while the cerata resemble the coral tentacles. The egg masses of P. goniophaga sp. nov. are unique among Phestilla spp. egg masses in being bright orange in color, and forming a coiled ribbon. Analysis of the COI, 16S rRNA and H3 genes of P. goniophaga sp. nov. also showed that this species is distinct from other congeneric species.

Toxicological effects of two organic ultraviolet filters and a related commercial sunscreen product in adult corals.

Corals are exposed to organic ultraviolet (UV) filters and other personal care product (PCP) ingredients in the environment, but the toxicities of organic UV filters and their related PCP to corals are not well understood. In this study, 7-day exposures were conducted to evaluate the toxicities and bioaccumulation of two organic UV filters, ethylhexylmethoxy-cinnamate (EHMC; octinoxate) and octocrylene (OC) (single- and combined-chemical tests), and diluted sunscreen wash-off water containing both active ingredients to the adult life stage of two hard coral species, Seriatopora caliendrum and Pocillopora damicornis. In the single-chemical tests, death (33.3%) and bleaching (83.3%) were only observed in the 1000 µg/L EHMC treatment of S. caliendrum. In the sunscreen product exposures, 5% sunscreen water (containing 422.34 ±â€¯37.34 µg/L of EHMC and 33.50 ±â€¯7.60 µg/L of OC at Day 0) caused high mortality in S. caliendrum (66.7-83.3%) and P. damicornis (33.3-50%), and tissue concentrations were up to 10 times greater than in the single-chemical exposures; co-exposure to EHMC and OC at similar levels to those in the sunscreen product resulted in bioaccumulation similar to the single-chemical tests. These results confirm the bioaccumulation potential of EHMC and OC and show that other ingredients in sunscreen products may increase the bioavailability of active ingredients to corals and exacerbate the toxicity of sunscreen products. Future studies on the toxicities of PCPs to aquatic organisms should not only focus on the toxicities of active ingredients.