Lunar Periodicity in Reproduction of Senatorial Scallop (Chlamys Senatoria Gmelin, 1791) in Asid Gulf, Masbate, Philippines

In Masbate, senatorial scallop Chlamys senatoria is one of the five commercially important species of scallop present in Asid Gulf, but its basic biology is poorly understood in the Philippines. To provide biological information for future conservation and management, the reproductive rhythm of senatorial scallop in relation to lunar phase was investigated from October 2016 to March 2017. Scallops were collected daily from the fishers’ catches and were measured, dissected, and processed for histological analysis; whereas, fecundity and size of eggs (diameter) were also determined. Ecological parameter such as bottom water temperature was monitored during the sampling period. Results showed that C. senatoria is a highly fecund species, which ranges from 8.3 X 105 to 2.1 X 106 oocytes per female and its sizes (oocytes) ranges from 53.8 µm to 72.5 µm while Gonado-somatic index (GSI) ranges from 3.2 to 7.1. Fecundity, egg diameter, and the GSI decreased during new moon (NM) and full moon (FM). GSI indicates that the onset of spawning activity commences during NM and FM. Environmental parameters that were monitored showed significant variations in relation to lunar phase. Spawning of scallop C. senatoria follows a lunar reproductive pattern, which was initiated and influenced by the variations of different factors such as temperature, water amplitude, and light as the effect of lunar/tidal cycles. These findings indicate that reproduction and necessarily spawning in the scallop are related to factors associated with lunar phases. Strategies for managing the resource can be formulated using the temporal dimension of lunar phases.

A novel system for intensive Diadema antillarum propagation as a step towards population enhancement

The long-spined sea urchin Diadema antillarum was once an abundant reef grazing herbivore throughout the Caribbean. During the early 1980s, D. antillarum populations were reduced by > 93% due to an undescribed disease. This event resulted in a lack of functional reef herbivory and contributed to ongoing ecological shifts from hard coral towards macroalgae dominated reefs. Limited natural recovery has increased interest in a range of strategies for augmenting herbivory. An area of focus has been developing scalable ex situ methods for rearing D. antillarum from gametes. The ultimate use of such a tool would be exploring hatchery origin restocking strategies. Intensive ex situ aquaculture is a potentially viable, yet difficult, method for producing D. antillarum at scales necessary to facilitate restocking. Here we describe a purpose-built, novel recirculating aquaculture system and the broodstock management and larval culture process that has produced multiple D. antillarum cohorts, and which has the potential for practical application in a dedicated hatchery setting. Adult animals held in captivity can be induced to spawn year-round, with some evidence for annual and lunar periodicity. Fecundity and fertilization rates are both consistently very high, yet challenges persist in both late stage larval development and early post-settlement survival. Initial success was realized with production of 100 juvenile D. antillarum from ~ 1200 competent larvae. While the system we describe requires a significant level of investment and technical expertise, this work advances D. antillarum culture efforts in potential future hatchery settings and improves the viability of scalable ex situ production for population enhancement.

The small polychaete Platynereis dumerilii revealed as a large species complex with fourteen MOTUs in European marine habitats

Recent studies reporting complexes of cryptic or pseudo-cryptic species with narrow geographic distributions have been challenging the cosmopolitan status of a fair number of marine benthic invertebrates. Morphologically similar species are often overlooked but molecular techniques have been extremely effective in signalling potential hidden diversity which, complemented with further detailed examination, might reveal unique morphological and ecological features. Evidence of morphological stasis, where no clear and stable morphological differences are apparent, can be exemplified by the annelids Platynereis dumerilii (Audouin & Milne Edwards, 1833) and Platynereis massiliensis (Moquin-Tandon, 1869). These sibling species, usually found among algae in marine intertidal and subtidal habitats, can only be distinguished by their different reproductive strategies and life histories. The former is gonochoric, with a single reproductive event in life (semelparous) transforming into a pelagic epitokous form called heteronereis, has free spawning synchronized by lunar periodicity and a larval stage with planktotrophic development; while the latter shows no epitokous transformation and is a protandrous hermaphrodite, characterized by egg brooding and lecithotrophic larval stages with a semi-direct development. In order to verify the possible existence of additional hidden Platynereis species within the P. dumerilii morphotype, we used a multi-locus approach to investigate 26 populations along Europe from the NE Atlantic and the Macaronesia islands (Azores, Madeira and Canaries) to the Western and Eastern Mediterranean Sea. We concatenated the mtDNA COI-5P, rDNA 16S and 28S-D2 sequences and performed a phylogenetic analysis through Bayesian inference (BI). To depict Molecular Operational Taxonomic Units (MOTUs), we applied three delimitation methods (ABGD, bPTP and GYMC) to the concatenated alignment, except for COI where we also applied the Barcode Index Number (BIN), implemented in BOLD, which is exclusive to this locus. Consensus MOTUs were defined based on the majority rule and, in case of draw, the most conservative MOTUs were chosen. We detected at least 14 MOTUs with 23.1% COI mean K2P distance (6.6 - 32.6%). The BI tree is split into three major clades (Clade A: MOTUs 1-3, Clade B: MOTUs 4-9 and Clade C: MOTUs 10-14), with MOTU 3 appearing to represent P. dumerilii sensu stricto and MOTU 9 P. massiliensis. This assumption is based on data from the Type locality and a previous study by Wage et al. (2017), which combined phylogeographic (COI barcode region), reproductive biology and life-history observations on some selected Platynereis populations thriving in the vent areas from the Italian islands of Ischia and Vulcano. Major Cade C seems to be pseudo-cryptic as some visible differences can be found in the specimens, as for example, the size of the tentacular cirri and lack of dorsal pigmentation, in contrast with Clades A and B, where only differences in pigmentation types were found so far. The Spanish archipelago of the Canary Islands and the whole Mediterranean Sea seem to be a cryptic hotspot. Five MOTUs are unique to the Macaronesia and five sympatric MOTUs are present in the Gran Canaria and La Palma islands alone. Additionally, three lineages were present exclusively in the Mediterranean with four sympatric MOTUs spotted in the southeast of Spain (Calpe) and the Greek island of Crete. Three out of four NE Atlantic MOTUs are shared with the Mediterranean with one exclusive to this part of the continent. Failure to recognise this hidden biodiversity may compromise the accuracy and the interpretation of biomonitoring data or other relevant ecological studies. Integrative taxonomy is thus essential to solve these uncertainties and to allow naming the involved undescribed species. Otherwise, most molecular data providing enough support for species hypothesis will continue to be unused, and large fractions of biodiversity will persist unnoticed.

The daily resolved temperature dependence and structure of planktonic foraminifera blooms

Planktonic foraminifera (PF) life cycles are highly sensitive to marine conditions, which are evolving rapidly due to anthropogenic climate change. Even though PF shells in the sedimentary record serve as prominent proxies of past ocean conditions, very little is still known about their life cycles, particularly in oligotrophic environments. Here, we present a full annual record of PF fluxes (> 63 µm) from the oligotrophic Gulf of Aqaba, northern Red Sea, sampled at daily timescales during 2015–2016 using an automated time-series sediment trap. These results are coupled with daily surface chlorophyll-a concentrations, sea surface temperatures (SSTs), particulate organic carbon and bulk fluxes, together with monthly resolved vertical profiles of chlorophyll-a, temperatures and nutrient concentrations. The annual cycle of PF fluxes is controlled by SST changes that drive water column mixing and changes in food availability. PF species flux patterns and succession dynamics vary throughout the year, displaying large variability on previously undocumented daily-weekly timescales, and are not synchronized with lunar periodicity. On daily timescales, spring blooms show a complex structure and interplay between SSTs, chlorophyll-a surface concentrations and PF fluxes. These events deliver about a third of the total annual PF flux over a period of several weeks.

Synodic lunar phases and suicide: based on 2605 suicides over 23 years, a full moon peak is apparent in premenopausal women from northern Finland

Suicide data for this study were available for the period of March 1988 to June 2011, and involved 2111 male and 494 female victims from the Finnish province of Oulu. Data for lunar phases during that period were categorised into three groups: new moon (<25% visible), full moon (>75% visible) and other times with values in between. Seasonal effects were controlled with definitions for winter (Nov, Dec, Jan), spring (Feb, Mar, Apr), summer (May, June, July), and autumn (Aug, Sep, Oct). Suicide occurrences during different lunar phases were compared with their expected distribution using multinomial tests with all tests being two-tailed. Statistical significance was set at p < 0.05. No correlation between suicides and moon phase in any of the four seasons was apparent for male victims, but in winter for women it was (p = 0.001). Further analysis of the data revealed that the full moon association was statistically significant only for premenopausal women, defined as female victims younger than 45 years of age. To explain this unexpected finding a number of factors were considered, e.g., the darkness of a northern Finnish winter with increases of SAD and depression especially in premenopausal women, the influence of the lunar periodicity on the menstrual cycle, and cosmogeophysical effects on the humoral and autonomous nervous system.

Description of the adult and immature stages of Clunio ponticus Michailova, 1980 (Diptera, Chironomidae), from the Black Sea, Varna, Bulgaria

The mature and immature stages of Clunio ponticus Michailova, 1980 are diagnosed and described based on associated material recently collected in the marine littoral zone of Varna, St-Konstantin and Helena Resorts, Black Sea (eastern Bulgaria). Male and female adults, pupae and larvae of C. ponticus can be easily distinguished from other known European Clunio species on the basis of some atypical features found in the male and female adults, pupal exuviae and fourth instar larvae. In addition, the biological cycle (reproduction and emergence) of C. ponticus is not synchronized with lunar periodicity (new and full moon) as for some other known Clunio species from Europe, but closely related to the typology of the intertidal zone along the coastline of the Black Sea. This indicates that this species is a local biogeographic representative of the ‘Pontus Region’, which includes the eastern coastline of the Black Sea. Remarks on related known Clunio species from Europe with comments on the ecology and geographical distribution of C. ponticus are given.