Abundance and distribution of marine litter on the beaches of Okinawa Island, Japan.

This study evaluated the distribution and abundance of marine litter on 30 beaches around Okinawa Island, Japan. Beach quality indices and multivariate statistical analyses were used to assess the quality of the beaches and their pollution patterns. A total of 11,626 items weighing 513.49 kg with an average density of 0.13 ± 0.10 items/m2 were collected. Litter was dominated by plastics (81.72 %), broken glass (8.38 %), and cigarette butts (7.44 %), and 74.05 % of total litter was from land-based sources. Single-use plastics (SUPs) were present in all surveyed beaches and made up 30.54 % of the total litter. The clean coast index (CCI), plastic abundance index (PAI), and hazardous index (HI) were between 0.1 and 7.6, 0.1-4.0 and 0.01-1.42, respectively, indicating low to moderate levels of pollution of Okinawan beaches. This study should aid in the formation of strategies to deal with marine litter in Okinawa, other areas of Japan and the Asia-Pacific region.

Sexual Reproduction in Zoanthus kuroshio and Isaurus tuberculatus (Cnidaria: Anthozoa: Zoanthidae) in Southern Japan.

Among family Zoanthidae (Anthozoa: Hexacorallia: Zoantharia), Zoanthus and Isaurus are widespread benthos on coral reefs, but the reproductive biology of both genera is generally unknown. Accordingly, sexual reproduction of two Zoanthidae species in Japan, Zoanthus kuroshio in Okinawa, and Isaurus tuberculatus in Okinawa and Kochi, was investigated by annual sampling. Between 2012 and 2013, polyps of tagged colonies of Z. kuroshio and I. tuberculatus were sampled monthly, and gonads in mesenteries were examined under a stereomicroscope. In Z. kuroshio, sizes of oocytes were estimated and in situ spawning observations were conducted at night at Okinawa sites. Monthly sampling indicated that gametogenesis periods of both species in Okinawa were from May to August, and oogenesis set in earlier than spermatogenesis, and thus both species can be considered protogynous functional hermaphrodites. On the other hand, I. tuberculatus in Kochi had hermaphroditic polyps in July and August. Notably, fertile colonies of Z. kuroshio were not only hermaphrodites but also included exclusively male and female colonies. Overall, four sexual types were identified in Z. kuroshio: male, female, functional protogynous hermaphrodites, and unclassified sterile colonies. In situ gamete release of Z. kuroshio was observed in August 2012 and July to August 2013. First spawning of the year occurred 1 day after the new moon; colonies shed their bundles 3.5-4 h after sunset. We speculate that lunar phase and time after sunset influence spawning timing in Z. kuroshio. Basic knowledge on sexual reproduction of Zoanthidae is critically needed to better understand the basic biology of these benthic cnidarians.

An Indo-Pacific coral spawning database.

The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology.

Gametogenesis and Inter-annual Variability in the Spawning Pattern of Acropora hyacinthus in Northwestern Philippines.

Emmeline A. Jamodiong, Elizaldy A. Maboloc, Ronald D. Villanueva, and Patrick C. Cabaitan (2018) Acropora hyacinthus is a fast-growing tabular coral that dominates the shallow water coral assemblage in the Magsaysay reef at the Bolinao-Anda Reef Complex (BARC), northwestern Philippines. The timing of gamete development was investigated for A. hyacinthus through dissection and histological analyses of coral fragments that were collected monthly from February 2014 to April 2015 from the 22 tagged colonies. The spawning time was identified by the presence of oocytes in the sampled A. hyacinthus colonies through rapid sampling from January to March 2014, 2015 and 2016. Results show that A. hyacinthus is a hermaphroditic broadcast spawning coral with an annual gametogenic cycle. Acropora hyacinthus exhibits an extended release of gametes across 2 to 3 months, from February to April. Major release of gametes occurred in March. Two types of extended spawning patterns that are unique in this region were observed in this species (i.e., asynchronous spawning amongst colonies and split spawning of individual colonies). This study contributes to the increasing knowledge on the coral reproductive strategies in northwestern Philippines and provides information on availability of coral materials for coral reef restoration efforts and management.