Volume 59, Issue 2-3

The stoloniferous hydrozoan Obelia geniculata frequently colonizes late-harvested blades of the aquacultured Saccharina japonica. To understand the corresponding changes at protein level, we compared the proteomic profiles in hydrozoan-colonized and healthy tissues. Our results showed that 107 and 75 protein spots were detected in colonized and healthy tissues, respectively. Among them, 7 and 16 identified proteins were significantly up- and down-regulated, respectively. Up-regulated proteins of cell-division cycle 46/minichromosome maintenance protein 5 and glutamyl-tRNA reductase were found mostly in hydrozoan-colonized tissues but were rare in healthy tissues. Microcompartments protein, carboxysome shell peptide, biotin synthetase, serine/arginine-rich splicing factor and a two-component response regulator were up-regulated in hydrozoan-colonized tissues. However, downregulated proteins of phosphoglycerate kinase, expansin 6, translation initiation factor 3, calcium/calmodulin-dependent protein kinase II inhibitor 2 and 50S ribosomal protein L1P were found mostly in healthy tissues but rare in hydrozoan-colonized tissues. Transmembrane protein, protoporphyrinogen oxidase, dual oxidase 2, PIH1 domain-containing protein 2, GTPase-activating protein alpha, threonyl-tRNA synthetase, flavanone 3-hydroxylase, uncoupling protein 3, bromoperoxidase 7, peptide release factor 1, and interaptin were down-regulated in hydrozoan-colonized tissues. Most of the up- and down-regulated proteins are known to be related to stress control, signal transduction and photosynthesis.

Laboratory experiments were set up in order to assess light and temperature requirements for survival, growth and reproduction of specimens of Lithophyllum stictaeforme collected at 30–35 m depth in the NW Mediterranean. Three replicates were grown in a variety of regimes, with temperature varying from 10 to 26°C, photoperiod from 8:16 to 16:8 h light:dark, and irradiance from 5 to 75 μmol photons m -2 s -1 . Other experiments were designed to imitate seasonal changes of temperature and photoperiod, and were maintained successively in temperature and photoperiod conditions of winter, spring, summer and autumn, and each set of conditions was combined with irradiances of 5, 10, 20, 50 and 75 μmol photons m -2 s -1 . Survival of thalli depended on both irradiance and temperature, with a strong interaction between these factors. The longest survival of thalli (>5 years) was observed at 20 μmol photons m -2 s -1 combined with 10–12°C and an 8:16 h light:dark regime, while the lowest survival (<0.6 years) was observed at 75 μmol photons m -2 s -1 combined with 24–26°C and a 16:8 h light-dark regime. No marginal extension was observed in any of the culture conditions examined. The time required for reproductive structures to mature was always <1.5 years and was correlated with thallus survival; it was dependent on temperature/photoperiod and specimens living at higher temperatures released their reproductive cells earlier. In the culture conditions that simulated seasonal changes, conceptacles matured in autumn, in agreement with the behaviour of field specimens, except at 75 μmol photons m -2 s -1 , when they matured earlier due to irradiance stress.

Subantarctic and Antarctic regions remain little explored with regards to their seaweed diversity. This study is based upon collections in the early 1970s and 2007–2013. It is supported by sequencing COI (mitochondrial cytochrome oxidase I) and reports new records for four species of brown algae ( Hincksia granulosa , Hincksia sandriana , Myriotrichia clavaeformis , Syringoderma australe ), four red algae ( Erythrotrichia carnea , Paraglossum salicifolium , Phycodrys antarctica , Plumariopsis eatonii ), one green alga ( Chaetomorpha aerea ) and of the oomycete Anisolpidium ectocarpii . A further four brown algae are reported at genus level and discussed ( Cladostephus sp., Colpomenia sp., Dictyota sp., Punctaria sp.). Observations of the biology of three brown algal taxa ( Cladothele decaisnei , Geminocarpus geminatus , Halopteris obovata ) from the region are also reported here.

Evidence is presented that the marine macroalga Pseudobryopsis papillata Nasr (Bryopsidaceae, Chlorophyta), described by Nasr in 1944 from the Red Sea, is conspecific with the Mediterranean generitype Pseudobryopsis myura (J. Agardh) Berthold in Oltmanns. Although Ps. myura was originally depicted as having non-papillate gametangia, recent and past collections of this species in the Mediterranean clearly show papillate gametangia, thus erasing the primary reason for distinguishing it from Red Sea populations. In addition, similar branch patterns and thallus lengths support the synonymization of these two species.

The species diversity of the red algal genus Ochtodes from Caribbean Mexico is reconsidered after a new collection in this region. A combined analysis of plastid rbc L sequences together with detailed morphological studies has confirmed the presence of two undescribed species in addition to Ochtodes secundiramea . Ochtodes akumalensis sp. nov. has abundant spiny branches, especially on the main axis, and robust cystocarps densely aggregate at the branch tips. In contrast, Ochtodes maguachaveziae sp. nov. lacks spiny branches and gland cells, and bears scattered cystocarps near the branch apices. Both species develop cruciately to obliquely divided zonate tetrasporangia. The molecular analysis showed that O. maguachaveziae and O. akumalensis represent separate taxonomic entities with a 1.8% sequence divergence between them. The description of two new species of Ochtodes from Caribbean Mexico suggest that our knowledge of the regional diversity of this genus is still incomplete.

Species of Ulva are distributed worldwide in various aquatic habitats and their morphological characters change considerably in response to environmental conditions, which makes identification in this genus problematic. All Ulva species so far described from the Persian Gulf, Iran, have been identified by classical taxonomic methods. In this study, Ulva spp. collected from the Persian Gulf were identified by combined morphological and molecular methods. We sequenced the internal transcribed spacer ITS2 and the rbcL gene in 15 specimens, representing typical morphotypes of over 50 samples. Maximum likelihood, maximum parsimony and Bayesian inference (BI) phylogenetic reconstructions using ITS and rbcL revealed clades, which we identified as Ulva chaugulii, U. paschima and U. ohnoi . These three species have not been recorded from the Persian Gulf, Iran before. The morphology of U. chaugulii differed considerably from its species description, showing further evidence for extreme intraspecific variation in morphology in this cosmopolitan genus.

A study of vertical distribution of dinoflagellate cysts in recent sediments was conducted for the first time in the Far Eastern seas of Russia. Dinoflagellate cysts were studied in sediment cores retrieved from five stations in Amur Bay (Peter the Great Bay, Sea of Japan) in 2010 and 2013. The Scrippsiella trochoidea complex was the dominant type of cyst, the average proportion of which (in the entire sediment cores) reached 39% of the total cyst abundance. The maximum abundance of S. trochoidea complex reached 5513 cysts g -1 dry sediment. Cysts of the S. trochoidea complex were found to remain viable in the sediments after exposure to sub-zero temperatures. The identification of S. trochoidea in the Far Eastern seas of Russia was first confirmed by using biomolecular genetic analyses. The study of vertical distribution showed that cysts of this species dominate the upper sediment layers (0–10 cm). A tendency for abundance to increase from the shore toward the middle part of the bay was observed in the spatial distribution of cysts.

There is growing interest in carbon stocks and flows in seagrass ecosystems, but recent global reviews suggest a paucity of studies from Africa. This paper reviews work on seagrass productivity, biomass and sediment carbon in Africa. Most work was conducted in East Africa with a major geographical gap in West Africa. The mean above-ground, below-ground and total biomasses from all studies were 174.4, 474.6 and 514 g DW m -2 , respectively with a global range of 461–738 g DW m -2 . Mean annual production rate was 913 g DW m -2 year -1 (global range 816–1012 g DW m -2 year -1 ). No studies were found giving sediment organic carbon, demonstrating a major gap in seagrass blue carbon work. Given the small numbers of relevant papers and the large geographical areas left undescribed in Africa, any conclusions remain tentative and much remains to be done on seagrass studies in Africa.

Calcification rates, as well as rates of photosynthetic inorganic carbon (Ci) uptake and relative electron transport (rETR), were measured by alkalinity titrations and pulse-amplitude-modulated (PAM) fluorometry in a simple experimental set up for Halimeda macroloba and Halimeda borneensis from Tangkhen Bay, Phuket, Thailand. While calcification was saturated at bulk seawater concentrations of ~0.3 and ~0.2 m m CO 3 2- , respectively, for the two species, photosynthetic Ci uptake was saturated at ~1.0 and 0.6 m m HCO 3 - , respectively. Thus, the normal seawater concentrations of these two Ci forms (0.3 m m CO 3 2- and 1.7 m m HCO 3 - ) were viewed as saturating for both processes. rETR increased towards the end of the incubations as a function of irradiance despite the decrease in Ci uptake. This implies that part of the photosynthetic electron flow was diverted to processes other than CO 2 reduction under Ci-limiting conditions, and shows that fluorometry is not a good way to estimate photosynthetic efficiencies under such conditions. Based on the responses to pH and Ci reported here, we estimate that the predicted range of ocean acidification for 2100 will still allow for positive rates of calcification in these two Halimeda species.

Reproductive structures of the seagrass, Halodule wrightii Ascherson (shoal grass) are cryptic and ephemeral, but were found on several occasions at several sites over more than a decade in the subtropical Laguna Madre (USA). Structures align with descriptions for H. wrightii . Male, but no female flowers were found, but the numerous fruit-bearing shoots imply the occurrence of pistillate flowers. Mean seed bank density was 890 seeds m -2 (1900–5200 m -2 ). Sexual reproduction in H. wrightii is more common than previously believed and the seed bank reserve may contribute to its ecological role as a colonizer of disturbed sediments.

In the marine cyanobacterium Arthrospira sp. under high light, the electron transport activity of photosystem (PS) II was much higher than the activities of PSI and the whole chain, indicating the existence of an alternative electron sink in PSII. Under high light, the addition of n-propyl gallate (PG), an inhibitor of plastid terminal oxidase (PTOX), decreased photosynthetic electron transport significantly as compared with that under low light. A significant residual level of photosynthetic electron transport remained in the presence of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) under high light. The extent of DBMIB insensitive electron transport was close to that of PG sensitive electron transport, suggesting that the PTOX acted as an alternative electron sink, accounting for 27% of total PSII electron transport in Arthrospira sp. cells under high light.

The taxonomy of Saccharina longipedalis , a kelp species endemic to the brackish Lake Akkeshi in eastern Hokkaido, was reviewed. The external morphology of sporophytes collected from seven sites around the distribution boundary of S. longipedalis and Saccharina japonica var. diabolica were compared; it was confirmed that the diagnostic morphology of S. longipedalis , such as a long stipe and thin blade, was not solely characteristic of individuals that grew in and around the center of the lake, which is thought to be the unique distribution area of S. longipedalis . Sequence comparisons of a 5S rDNA spacer and four microsatellite regions and AFLP analysis revealed that genetic similarity was high between S. longipedalis and S. japonica var. diabolica . Also based on observations that the early development in hybrids of sporelings from the seven sites was normal, we conclude that S. longipedalis should be treated as S. japonica var. diabolica .