A new species of Terebellidae, Loimia ramzega sp. nov., has been identified from North Brittany beaches (English Channel). This new species is characterized by its gigantic size (max 650 mm, live), two pairs of lateral lappets on segments 1 and 3; first pair more ventral, second pair more developed and lateral but oblique, with wavy edge. Nine ventral pads from segment 2 (fused on segments 2 and 3), first three pads swollen, next ones subsequently decreasing in size. Three types of notochaetae, asymmetrically bilimbate, symmetrically bilimbate and capillary. Uncini pectinate with 6 teeth (some with 5 teeth) slightly decreasing in size, in one vertical row. Pygidium with about 14 long conical marginal papillae surrounding anus.

During a recent expedition to Ascension Island in the southern Atlantic Ocean, a polyplacophoran of the genus Acanthochitona was collected, corresponding to the first recorded species of this molluscan class from this remote island. A scanning electron microscope study reveals a close affinity to Acanthochitona subrubicunda, which was so far only known from the Cape Verde Archipelago. Due to the lack of comparable type material the new finding warrants a confirmed identification and is only tentatively attributed to Acanthochitona subrubicunda. It is hypothesized that the class Polyplacophora was either overlooked during earlier surveys or colonized the island in more recent time. If the latter scenario took place, a transport by ships is thinkable.

A new species of Mysidium from the eastern tropical Pacific, Mexico, is described, representing the second species of this genus described for the Pacific Ocean and the eighth species reported worldwide. Mysidium pumae sp. nov. is distinguished from the other species of the genus by several characters including: the lanceolate appendix masculina, 3× as long as wide, tapering distally, with a distal tuft of 16 setae and an inner proximal tuft of more than 30 setae, the male pleopod 4 with endopod bearing 3 setae, the exopod with 4 articles, the modified seta from article 3 of the exopod bifid, telson 2.3× as long as wide, distally concave. A table with the main differences among all the known species in the genus is provided.

The taxonomy of Mediterranean populations of Diodora is assessed based on new molecular (COI and 28S) data. The recently described Diodora demartiniorum Buzzurro & Russo, 2005, is found to be a valid species restricted to the Gulf of Gabès (Tunisia) but possibly occurring also on the coast of Libya. However, specimens from the Aegean Sea previously identified as D. demartiniorum are molecularly (and morphologically pseudocryptically) distinct and represent a previously unrecognized species here described as D. giannispadai n. sp. It is hypothesized that the current distribution of these two species corresponds to glacial refuges during Pleistocene climate changes.

The urohyal is incorporated within the hyoid and branchial arches and performs a significant role in the mouth opening-closing mechanism of fishes, and is considered a synapomorphy of teleostean fishes. Morphological variation of the urohyal, in terms of size and shape parameters, can allow species identification. Morphology of the urohyal in 49 species belonging to 43 genera and 29 families from the Persian Gulf and from the Oman Sea were compared using size and shape measurements. The results examine the suitability of using the urohyal morphology in differentiating fish species from this region; highlighting the taxonomic value of the urohyal, which until now, had been studied little in terms of use as a diagnostic feature in the classification of teleosts.

The examination of a collection of nudibranchs (Mollusca: Gastropoda: Heterobranchia) obtained during several expeditions to international waters off Newfoundland, North Atlantic, revealed the presence of rare species, new records for the area, and an undescribed species of Tritonia (described herein). This includes the first record of Dendronotus niveus Ekimova, Korshunova, Schepetov, Neretina, Sanamyan and Martynov, 2015 from the Atlantic Ocean and numerous specimens of the rare species Doridoxa ingolfiana Bergh, 1899, which is here redescribed. Other species collected are Flabellina cf. salmonacea (Couthouy, 1838), Dendronotus frondosus (Ascanius, 1774), Dendronotus robustus A. E. Verrill, 1870, Aldisa zetlandica (Alder & Hancock, 1854), Onchidoris bilamellata (Linnaeus, 1767), Colga villosa (Odhner, 1907) as well as an unidentified species of Aeolidiella. Anatomical characteristics and genetic barcode data are used to identify the species whenever it was possible. Ecological data, including substrate, associated fauna and bathymetric range are provided.

High plasticity in cephalopod populations shows dramatic changes in their biological traits. Commercial catches of Mayan octopus (Octopus maya) in six localities of the state of Campeche, Mexico, were sampled monthly for five consecutive fishing seasons (2005–2009) in order to describe variations in population structure and maturation. Octopus maya grows and matures during the fishing season, from August to December. Spent individuals predominate in January and February, revealing a year-long life cycle. However, the presence of a few spent females in all months sampled suggests that a small part of the population shows an extended spawning period. Overall sex ratios did not significantly shift from the expected 1:1 in most samples. Males are mostly mature while the majority of females are immature during the season. Use of illegal fishing gears (spear diving or pots) in central localities accounts for a larger share in mature females. Octopus size showed large interannual and geographic differences. Females mature at a larger size (1024 g body weight, BW; 124 mm mantle length, ML) than males (484 g BW; 91 mm ML). Size at maturity in both sexes varies more between seasons than between localities. Female ML at maturity is larger than the current minimum legal size and implications for current octopus fishing regulations are discussed.

Light adaptive strategies were studied in a comparative analysis of the congeneric seagrass species Zostera muelleri and Zostera marina at two case study areas in New Zealand and Germany. Surveys in intertidal seagrass meadows were conducted from pre-dawn until sunset on days when either low or high tide coincided with noon. The results show marked fluctuations of photophysiology (optimum and effective quantum yield, non-photochemical quenching, cycling of xanthophyll cycle (XC) pigments) over daily and tidal cycles. At both locations, we observed a near complete conversion (de-epoxidation) of violaxanthin to zeaxanthin at times with high irradiance and a rapid and complete re-epoxidation under subsequent lower light conditions. At the New Zealand site we also observed significantly larger XC-pigment pool sizes in seagrass leaves sampled in a week when low tide coincided with noon (larger daily fluence and higher maximum irradiance), compared with leaves sampled in a week when high tide was at noon. This dynamic adjustment of xanthophyll pool size has not been previously reported for intertidal seagrasses. It adds to our understanding of an important adaptive feature in a highly dynamic light environment and to the general ecology and adaptability of seagrasses.

Upside-down jellyfish (genus Cassiopea) can be found in tropical coastal waters worldwide. Until now reports of the genus from Brazilian waters have been scant. We report here medusae and scyphistomae collected from Cabo Frio, Rio de Janeiro state. Although we could not unambiguously identify the material using morphological criteria, genetic sequence data (COI) indicate that the Brazilian jellyfishes are genetically similar to those from Bermuda, Hawaii and Florida, which are related to specimens from the Red Sea (Cassiopea andromeda). We hypothesize that the presence of C. andromeda in Brazil is due to an invasion event, as the scyphistomae were found growing over the known invasive ascidian Styela plicata. Estimation of divergence time between Brazil (Cabo Frio) and Florida/Bermuda populations is that it occurred at the beginning of ship movement to South America.

Common rock oysters Saccostrea cucullata (Bivalvia) were sampled from intertidal volcanic rocks at five sites around Ascension Island (central-east Atlantic) in austral winter 2012–2014. Their left valves were sectioned to reveal annual growth increments. Their periodicity was validated by the presence of specific growth marks in the increment sequence visible in consecutive years of sampling. No significant differences in shell height-weight relationships were revealed between sites. Marginal analysis of the increment width showed that S. cucullata accelerated their growth in cooler winter months and decelerated the growth in warmer summer months. Rock oysters in Ascension Island lived up to 14–16 years with maximum age of 26 years. Young oysters (1–5 years old) had the same growth rates both in shell height and weight in all sites. However, their starting point (size and weight of 1-year-old animals) was different in various sites, with largest animals occurring in the most protected site Northeast Bay with sheltered inlets and smallest animals inhabiting exposed to surf site of Letterbox. Growth in shell height was best described by von Bertalanffy growth function with the largest L∞ in animals inhabiting the windward side and smallest animals occurring in the leeward side of the Island. In summary, S. cucullata around Ascension Island lived longer but had slower growth than those from tropical regions of Southwest Asia probably due to comparatively low productivity observed in the central part of the equatorial tropical Atlantic.

The infauna of Chabahar Bay (Iranian Coast of the Gulf of Oman) was investigated using shallow water (less than 10 m) grab-samples between June 2013 and March 2014. The magelonid fauna of these samples was studied and prioritized, with four species being present: M. fauchaldi sp. nov., M. symmetrica, M. cf. cincta and M. crenulifrons. The new species differs from all known magelonid species within the Persian Gulf region in possessing polydentate abdominal hooks. A fifth species, currently undescribed, was also found. The validity of M. pulchella originally described from Kuwait is discussed in light of its closeness to M. crenulifrons. The main distinguishing feature between the two species is the presence or absence of crenulation of the anterior prostomial margin, a character shown to be variable in M. crenulifrons. Although differences between the type specimens of both species suggests M. pulchella to be a valid species, examination of further material and DNA analysis is needed.

It is necessary to monitor shell-associated polydorid worms owing to the risk that they pose to commercially important molluscs. This requires accurate identification, but is often hampered by morphological similarities among species, insufficient type specimens, and abridged species descriptions. Thus morphological characteristics and molecular sequences of the most harmful polydorid species, Polydora uncinata from Japan and Australia and Polydora hoplura from South Africa were compared to determine whether they represent two morphologically similar, but genetically distinct species, or a single species. A wide range of morphological variation (with respect to size, length of caruncle and pigmentation patterns) was observed in each species and population, and their variations largely overlapped and revealed them to be at the intraspecific level of a single species. This was confirmed by gene sequences of nuclear 18S and 28S rRNA that were completely identical for P. uncinata and P. hoplura. The mitochondrial 16S rRNA and cyt b gene analyses also showed no genetic differences between these two species. The tree topology of the mitochondrial cyt b gene did not reflect geographic differences but instead suggests artificial transportation of the species. We recommend the synonymization of P. uncinata with P. hoplura.

Spirobolbolaimus undulatus sp. nov. is described in intertidal sandy sediment from the East China Sea. The new species is characterized by six jointed outer labial setae much thicker and longer than the four slender cephalic setae, anterior and posterior pharynx bulbs, sclerotized multispiral amphid fovea, eight longitudinal rows of postamphideal setae, gubernaculum apophysis and many precloacal supplements. The new species differs distinctly from the type species Spirobolbolaimus bathyalis in the presence (vs absence) of jointed outer labial setae, eight additional small teeth, gubernaculum apophysis and many precloacal supplements and eight (vs six) rows of postamphideal setae. It differs from the other known congener Spirobolbolaimus boucherorum in the jointed outer labial setae (vs setae with smooth outline), three main teeth with eight additional small teeth (vs only three main teeth) and many distinct precloacal supplements (vs seven tiny papillate ones). We emend the diagnosis of the genus Spirobolbolaimus based on the description. Microlaimus pecticauda and Microlaimus spirifer possess two opposed reflexed ovaries, and thus are transferred from the family Microlaimidae to Molgolaimus of the family Desmodoridae: Molgolaimus pecticauda comb. nov. and Molgolaimus spirifer comb. nov.

During several sampling periods in the Northern Adriatic Sea (Mediterranean) from 2003–2010, one species of Pista and one of Pistella were found. They were initially identified as Pista cf. lornensis (Pearson, 1969), but detailed examination revealed the presence of two new species, one belonging to the genus Pistella Hartmann-Schröder, 1996, P. rovignensis sp. nov. and one belonging to the genus Pista, P. adriatica sp. nov. These two species differ from each other in the structure of the branchiae, shape of lateral lobes and the structure of the anterior thoracic uncini. The two new species are compared with other species of Pistella and Pista currently known. The relationship of Pistella and Pista is confusing and a complete revision of the two genera is urgently needed together with other genera characterized by having long-handled thoracic uncini.

The study analyses the role of non-indigenous invertebrates in the food webs of two eutrophic brackish estuarine ecosystems of the Baltic Sea: the Neva River estuary and the Curonian Lagoon, with the aim of clarifying several questions such as what trophic levels were occupied by newly established species (mainly amphipods and mysids) and whether they can affect the native benthic invertebrates as a result of their possible carnivorous nature. Stable isotope analysis (δ15N values) and gut contents analysis of field-collected specimens were used to estimate trophic level and trophic links of the newly established malacostracan crustaceans, while their consumption rates when feeding as carnivores were measured experimentally. The δ15N analysis allocated four trophic levels (TL) in the coastal food webs of both studied ecosystems with the lowest δ15N (2–4‰) for detritus and algae and the highest for fish (12–14‰). Through their high abundance, non-indigenous crustaceans (Pontogammarus robustoides, Gmelinoides fasciatus, Obessogammarus crassus, Gammarus tigrinus, Limnomysis benedeni and Paramysis lacustris) have become important members of food chains of the studied ecosystems. Their trophic position varied significantly within species during ontogenesis. This suggests that they turned from being typically detritivores/plantivorous (TL 2–2.4) at juvenile stages to omnivores (2.5–3) or to carnivores (>3) as adults. Assessment of the predation pressure by the adult amphipods on other coexisting invertebrates (in the example of the Neva Estuary) showed a low or medium impact, depending on species of predator and productivity of its potential prey organisms.

Sponges together with associated bacteria form complex holobionts governed by various relationships established between the partners. Molecules of communication may participate in the homeostasis of these biological associations. Bacteria produce N-acyl homoserine lactones to communicate. In the present study, we characterized 102 cultivable bacteria isolated from the sponge Suberites domuncula at the genus level and described their production of AHLs during 96 h of culture in a Marine Broth medium. The presence of AHLs was monitored using the Escherichia coli pSB406 reporter strain. Sixty-seven bacteria were AHLs positive. Among them, 46 were related to the Gammaproteobacteria, eight to the Alphaproteobacteria, seven to the Firmicutes and six to the Flavobacteria. The kinetic production of AHLs was determined and compared with a reference bacterium, Pseudomonas aeruginosa PAO1 (pDA224). We established three profiles of AHLs production with no definitive pattern related to an order, a family or a genus of bacteria.

During ArcticNet surveys aboard ‘CCGS Amundsen’ in 2011, several subtidal stations located in Canadian Archipelago were sampled in order to study the composition of their benthic communities. Among the abundant material sampled, several specimens of rare polychaete species were found. Examination of this material showed four species not previously recorded in the area, and a new species described herein. Descriptions of these specimens are given in this work. Ophelina brattegardi Kongsrud et al., 2011 is characterized by a body composed of 27–28 chaetigers, by having the parapodia of the last four chaetigers shifted to the ventral side of the body, and by lacking branchiae in mid-body chaetigers. Macrochaeta polyonix Eliason, 1962 is unique within the genus in having several (instead of one or two) compound neurochaetae in anterior parapodia. Chaetozone acuta Banse & Hobson, 1968 is characterized by having spines from anterior third of the body and arranged in bundles composed of just a few chaetae. Chaetozone jubata Chambers & Woodham, 2003 can be distinguished from similar species by having very long capillary chaetae from chaetiger 2 or 3. Finally, Dialychone hervyae n. sp. is characterized by bearing four pairs of radioles with narrow flanges, by the bilobed tip of its first peristomial ring that projects beyond the collar, and by the paleate thoracic notochaetae bearing long mucros.

During quantitative surveys two new species of Cirratulidae from subtidal bottoms of the Atlantic coast of Argentina were collected. They belong to the genera Monticellina and Chaetozone. Monticellina morae sp. nov. is characterized by the presence of a long peristomium of smooth appearance, but triannulated at SEM, bearing the dorsal tentacles in the posterior part, with the first pair of branchiae posterolateral to the dorsal tentacles in chaetiger 1. The body is divided into three parts, an anterior region laterally expanded and with crowded segments, a middle region with beadlike chaetigers and an inflated and crowded posterior region. Chaetozone larae sp. nov. is characterized by an inflated dorsally and laterally expanded anterior crowded region. Peristomium biannulated laterally, with a dorsal crest on the first and second annuli that occupy the entire width, and then a narrow crest in the following annulus (interpreted as an achaetous segment). Capillaries are lanceolate, short and long, with acicular spines curved, forming partial cinctures. In addition, a comparative table of all described species of Monticellina is included and the distinctive characters are discussed.

Using partial sequences of two mitochondrial genes, cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (12S rRNA), and one nuclear gene, 28S ribosomal RNA (28S rRNA), we investigated population genetics of the holoplanktonic shrimp Lucifer hanseni Nobili, 1905 in the Indo-Malayan Archipelago (IMA), encompassing Andaman Sea, Malacca Strait, Gulf of Thailand, Borneo Island, Philippines (hereafter collectively referred to as the Thailand-Malaysia-Philippine area: TMP), Celebes Sea (CS), and the waters near islands in the Western Pacific (WP) including Palau, Papua New Guinea and Solomon Islands. The samples from the TMP showed the highest number of haplotypes. Significant phylogeographic structure was found in the L. hanseni populations (ΦST = 0.832 for COI, 0.159 for 12S rRNA, 0.783 for 28S rRNA). The total number of haplotypes was 46 in COI, 28 in 12S rRNA and 23 in 28S rRNA. The haplotype network analyses revealed two major clades for COI (subgroups: TMP + CS, WP) and for 12S rRNA and 28S rRNA (TMP, CS + WP). The CS and WP populations appeared isolated from the TMP populations. The samples from the CS showed low genetic diversity compared with the other samples at both haplotype and nucleotide levels, suggesting that the population CS experienced bottleneck events. This is the first demonstration of significant genetic structure of a holoplanktonic metazoan in IMA, which is suggested to be synergistically influenced by historical events (vicariance) and contemporary oceanographic circulations and corroborates the results of previous studies on other benthic/demersal animals with mero-planktonic phases.

A new Spiogalea species is described from South-east Brazil. The specimens were collected in muddy bottoms during a large survey (15–3000 m) in southern Brazil. This genus comprised, up to now, only one species described from Capbreton Canyon (Bay of Biscay). The new species differs from the type-species, mostly in the morphology of the prostomial chitinous plate, a character restricted to the genus Spiogalea. With this new species, the generic diagnosis of the genus was amended.