Introduction of species is a major driver of global change and loss of biodiversity in ecosystems. The Mediterranean Sea is the most heavily invaded region in the world by introduced seaweeds. The fan mussel Pinna nobilis is the largest Mediterranean bivalve, and a protected species, present at depths from 0.5 m to 60 m. In Cabrera National Park marine protected area (MPA) (Balearic Islands, north-western Mediterranean) the population of P. nobilis is affected by the invasive seaweeds Lophocladia lallemandii and Caulerpa racemosa; however the extent of this colonization on the bivalve is unknown. Therefore, the main aims of the present study were to: (1) determine the extent of invasion of L. lallemandii and C. racemosa on the P. nobilis population; and (2) test if this invasion showed differences with depth. This is the first study assessing invasion by seaweeds on a large bivalve in a high density P. nobilis population. Pinna nobilis was distributed in all seagrass meadows surveyed within the MPA; we found a total of 872 live P. nobilis individuals, 449 and 423 of which were found at 10 and 20 m depth, respectively. High cover of L. lallemandii and low presence of C. racemosa were detected in the P. nobilis population, being quantified in 49.37% and 1.38% of the population of P. nobilis, respectively. Bathymetric differences on Lophocladia epizoism over P. nobilis has been recorded in this study; with increasing values of L. lallemandii cover index, biomass and volume at deeper depths. Pinna nobilis could be a preferential substratum for L. lallemandii in Posidonia oceanica meadows in deeper waters, acting as a stepping-stone for invasive seaweeds and facilitating the invasion throughout seagrass meadows.

This study investigated the presumed nursery function of mangroves for the ichthyofauna in East African swamp forests, Mida Creek. The species and size composition of the fish fauna and their trophic interactions were studied for five stations. Samples were collected during 5–6 consecutive days close to spring tide in mid-July 2011. Fish were caught using different types of passive fishing gear, such as large and small fyke nets, gill nets and, additionally, beach seines. All individuals were identified to species level, measured and preserved for further analyses. Stomach content analysis was applied to provide information about their diet. Stable isotope analysis was used to detect whether the source of primary production for the higher trophic levels is mangrove-related or not. A total of 27 fish species was recorded in a catch of 938 teleost specimens. Our analyses showed that a majority of fish belonged to the zoobenthivorous/omnivorous trophic mode, since they were partially feeding on invertebrates and on various other food sources. Two species (Sphyraena barracuda and Synodus variegatus) exhibited a mixed diet, with a piscivorous preference. Results concerning the population structure suggested that the fish community of Mida mainly consists of transient species. Juveniles were numerically more abundant in the whole Creek than adults. These findings support the hypothesis of a nursery function of the mangrove forests, Mida Creek.

A floristic study of marine macrophytic algae and Cyanobacteria in the splash and intertidal zones at Luhuitou reef, Sanya Bay, Hainan Island, China, was conducted during the rainy and dry seasons of 2008−2012 utilizing 148 of the most common species. Macrophytic algal diversity increased from the splash zone to the low intertidal zone, while cyanobacterial diversity decreased. In the upper and middle intertidal zones, the dominant species (primarily highly productive ephemerals) changed frequently throughout each year. In the low intertidal zone, the dominant species (mainly annual fleshy, foliose and coriaceous forms) also changed. In the dry season, species numbers were 33% higher than in the rainy season. During the rainy season, Cyanobacteria dominated the splash zone, while green and red algae dominated in increasing numbers from the upper to the low intertidal zones. During the dry season the splash zone was devoid of all macrophytic algae, and only one species of Cyanobacteria survived. In the upper intertidal, Cyanobacteria and red algae prevailed, while in the mid and low zones, red and green algae were the most diverse. In spite of heavy pollution in Sanya Bay, there was no evidence of dramatic changes in species numbers or composition, and the marine flora was similar to that of unpolluted regions in the Indo-Pacific.

Due to the input of humic substances from freshwater run-off into the marine habitat, the influences of such substances on marine organisms should not be neglected. We here investigate the effect of a humic acid (HA) extract from the North Sea, characterized by spectroscopic techniques and carboxylic and phenolic group content, on the growth of different algae. Two benthic pennate diatoms isolated from the Baltic Sea, Navicula ramosissima (C. Agardh) Cleve, 1895 and Entomoneis paludosa (W. Smith) Reimer, 1975, as well as two tychopelagic centric diatoms isolated from the North Sea, Melosira nummuloides C. Agardh, 1824 and Paralia sulcata (Ehrenberg) Cleve, 1873, were employed. The concentrations of pigments (fucoxanthin, diadinoxanthin, chlorophyll-a and β-carotene) and nutrients were also measured. Adding low concentrations of naturally humic substances (5.5 mg of C l−1) to the algae cultures resulted in enhanced growth rates compared to the control experiments, possibly due to the increase in the bioavailability of trace metals or other nutrients.

Diversity of hard corals is investigated on the reefs of two Iranian islands, Qeshm and Larak, located in the Persian Gulf. The corals were sampled and photographed and their percentage cover was estimated by diving in June 2008 and February 2009. Thirty-eight coral species belonging to 20 genera and nine families were identified, of which three species are new records from the Gulf. Coral diversity was higher in Larak Island, and in total, Acroporidae and Faviidae were the most diverse coral families. Acropora (83%) had the highest percentage cover in Larak Island, while the maximum percentage cover in Qeshm Island was for Porites (52.96%). Canonical correspondence analysis distinctly plotted the study sites against environmental variables. Salinity and pH were the most effective variables on the coral diversity, and had positive correlations with the frequency of several species including Pocillopora damicornis, Platygyra acuta and Acanthastrea maxima, while they had negative correlation with another group of other corals, including Plesiastrea devantieri, Acropora downingi and Psammocora digitata (P < 0.01). Water clarity had positive correlations with some coral species, including Cyphastrea serailia and Coscinaraeamonile, and negative correlations with other species such as Leptastrea transversa and Acropora arabensis. Diversity of a number of corals mainly Porites lutea and Cyphastrea chalcidicum had high affinity with the water temperature. The results of this study supported the existence of diversified coral communities in Iranian islands, while showing that their spatial and temporal distribution can be affected by environmental variables.

Reproductive division of labour is well-known in several animal groups but the ecological factors driving the evolution of such social organization are still being discussed. Recent studies have discovered social organization in four marine species of trematode parasites having two distinct castes specialized for reproduction and defence of the clonal intra-molluscan larval colony, respectively. Here, we provide novel evidence for social structure also in colonies of the trematode Himasthla elongata infecting the common periwinkle Littorina littorea. We found two types of rediae, the parthenogenetic larval offspring of the parasite: small non-reproductive rediae and considerably larger reproductive rediae. Both redial types possessed a digestive system, collar and posterior appendages and, hence, aside from dimensions, were morphologically similar. However, in vitro experiments showed that non-reproductive morphs attacked heterospecific competing parasites at a higher rate (2–3 fold) than reproductive morphs did. No within-colony antagonism was observed. In contrast to a previous study on a congeneric trematode species, our findings suggest a relatively weak caste formation in H. elongata, possibly resulting from a corresponding weaker level of interspecific competition.

The gametogenic cycle and life history of Nicolea uspiana (Nogueira, 2003) (Polychaeta: Terebellidae) was studied by taking monthly samples over a 13 month period. Each month, 10 females were sorted; 50 oocytes were removed from the coelom of each specimen, and the maximum diameter was determined. Additionally, 10 males were sorted and 100 gametes were randomly selected from each specimen to evaluate their shape and maturation stage. This species is gonochoric and exhibits slight external sexual dimorphism (in the shape of the nephridial papillae). The sex-ratio of N. uspiana was 2.4 male for each female. The initial gametic stages of both sexes are produced in special structures called nephromixia. Oogenesis is extra-ovarian, and the germ cells are clumped and surrounded by follicle cells. These cells are ovulated into the coelomic fluid, and yolk synthesis occurs in this cavity. The maximum diameter of oocytes measured, 225 µm, showed that these eggs fall into the size-range for lecithotrophy. Furthermore, N. uspiana is an iteroparous species, as the mature individuals can breed several times during their lifetime. Male gonads release germ cells early in development, and sperm maturation also occurs in the coelomic fluid. The male gametes consist of flattened plaques of germ cells attached on their anterior part by a cytophore assuming a rosette-like appearance. Following maturation of the male cells, the spermatids produce arrays of stiffly vibratile tails, assuming a morula shape. The reproductive patterns and life history of the terebellids are also discussed.

A new species of the sabellid genus Pseudobranchiomma is described from 50 cm depth in dock fouling from the southern Gulf of California. Pseudobranchiomma schizogenica sp. nov., belongs to a group of six species characterized by having radiolar serrations extending for most of the radiolar length. The new species is characterized by the presence of a unique set of features related to the covering of the peristomium by lateral collar margins, the shape of the first ventral shield, the size of interramal eyespots, and the width of the hood of thoracic and abdominal spinelike chaetae. Information about live and post-fixed colour, glandular pattern and reproduction is also provided. The new species described here is compared with all species in the former group. The presence of paired patches of cilia without heads (kinocilia-type) on ventral lappets and ventral shields of the collar, thorax and abdomen is documented for the first time in the genus Pseudobranchiomma. Dense aggregations of Pseudobranchiomma schizogenica sp. nov., on docks from the southern Gulf of California are predominantly a result of asexual reproduction taking place during summer, when 82% of the population reproduces by architomy.

During the Capbreton cruises (1987–1990), samples of bathyal benthic macrofauna were taken at 37 stations situated along the continental slope (480–1113 m depth) of the Capbreton Canyon (Bay of Biscay, north-east Atlantic). Ten species of polychaetes belonging to six genera (Melinna, Eclysippe, Amphicteis, Anobothrus, Glyphanostomum and Tanseimaruana) of the family Ampharetidae Malmgren, 1866 were collected at 13 of these stations. Most of these species are reported for the first time in the area. Amphicteis aff. wesenbergae is reported for the first time after its recent description and a new species belonging to the genus Glyphanostomum is here described. Moreover, the finding of Melinna monoceroides represents the northernmost record of the species; Tanseimaruana vestis is recorded for the second time from the East Atlantic after its recent finding in Icelandic waters; Anobothrus aff. gracilis is reported for the second time from the Iberian Peninsula, representing, the southernmost record of the species in the Atlantic Ocean. The potential identification of two fragments of an Ampharetinae indet as Anobothrus laubieri, a deep water Arctic species, is discussed.

A new genus and species of Tanaidacea are described from the manganese nodule province between the Clarion and the Clipperton Fracture Zone of the equatorial North Pacific Ocean collected during the French/German BIONOD expedition in 2012. The new genus, Cheliasetosatanais, can be diagnosed by the propodal and dactylus setation and the maxilliped endite armament. The male is also described and, while being a dimorphic swimming male, still shares the diagnostic characters and posseses a fully functional maxilliped.

The mystacocarid Ctenocheilocaris galvarini is a member of the intertidal meiofauna in exposed sandy beaches along the coast of Chile. Originally described by Dahl (1952) from sub-tidal sediment off Isla Guafo, the only other published record is from semi-fine intertidal sand in Las Cruces. This paper presents a variety of new records of C. galvarini based on both quantitative and qualitative sampling of the coast of Chile between 18°S and 54°S. Ctenocheilocaris galvarini is found primarily in southern Chile, south of 32°, in the intertidal zone of intermediate beaches, in fine sand (Wentworth scale) most likely distributed between the level of the water-table and the surface, but avoiding dry sand.

A new species of Paracrenhydrosoma (Copepoda: Harpacticoida: Cletodidae) is described from samples taken from muddy bottoms in Jangmok, Geoje Island, Korea. The genus Paracrenhydrosoma is distinguished from other genera of the Acrenhydrosoma-complex (Acrenhydrosoma, Dyacrenhydrosoma and Neoacrenhydrosoma) by carrying an antennal exopod with two setae, P1 endopod with three setae, P3 endopod with two setae and P5 exopod with two setae. The new species differs from its congeners as follows: bifid rostrum on anterior margin, long caudal ramus, exceedingly long baseoendopodal mucroniform process of female P5 that reaches the end of the second free abdominal segment, and modified P3 endopod of male. A tabular key to aid in the identification of the Acrenhydrosoma-complex is provided. The worldwide distribution of the Acrenhydrosoma-complex is summarized and discussed.

Sea food is very rich in lipids. The brown shrimp, Crangon crangon is a most popular and very valuable taxon in the White Sea, in the Mediterranean and in the Black Seas. The aim of this study was to determine the seasonal variations of lipids in C. crangon muscle tissue using gas chromatography–mass spectrometry. The lipids were separated into groups: neutral lipids (triacylglycerols, free fatty acids, sterols) and polar lipids (phospholipids), by high performance liquid chromatography with a laser light-scattering detector. Fatty acids were identified using the GC-MS technique. The mainly fatty acids were 16:0, 18:0 (saturated FAs), 16:1, 18:1 (monounsaturated FAs), 20:4 (ARA), 20:5 (EPA) and 22:6 (DHA). The largest amounts of fatty acids in the muscle were observed in spring; these were the result of collecting food after winter and before reproduction. The muscle lipid content was 32.2 ± 1.8 mg g−1. The summer was the poorest season and the lipid value was 7.7 ±0.4 mg g−1. The levels of muscle neutral lipids (NL) oscillated between 80% (autumn) and 90% (spring). The temperature and salinity has a significant influence on content and profile of fatty acids. This work will help to understand the biology, the seasonal variation in lipid mass, lipid classes content and fatty acids profile in the abdominal muscle of C. crangon.

The goal of the present study was to assess the temporal and spatial distribution of L. schmitti in three bays of the northern coast of the State of São Paulo, Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV), over a period of two years (1998 and 1999). Abiotic factors were monitored to test their influence on the distribution of the species through redundancy analysis. The shrimp were captured using a commercial fishing boat equipped with double-rig trawling nets at six sampling points. A total of 5658 individuals were collected during the study (4437 and 1221 in the first and second years, respectively). The number of individuals differed between years, bays, seasons and sampling locations. The highest number of L. schmitti was collected in MV (N = 2747), followed by UBM (N = 1649) and UBA (N = 1262). Shrimp abundance correlated positively with organic matter content, salinity and temperature, with the highest number of individuals collected from sites with intermediate levels of organic content (4 and 6%) and increasing when the sediment had a higher proportion of fine and very fine sand + clay. Abundance was also associated negatively with rainfall, given that the analysed population showed a seasonal pattern, with an increase in capture rate in those months following the rainy season. Average rainfall was 222.47 ± 138.68 mm, with a maximum of 538 mm and a minimum of 22.4 mm. The results obtained in this study suggest that, in the region of Ubatuba, temperature, salinity, organic content and rainfall modulate the distribution of these animals.

Egg clutch brooding and larval release behaviour are common among decapods and involve pheromone communication between the developing embryos and the brooding female. We tested caridean shrimps to determine whether their behaviour was similar to other decapods. In tests with aqueous extracts of crushed eggs and peptide pheromone mimic shrimps responded similarly to brachyurans and lobsters. The elongate body form of shrimps enabled us to focally stimulate body locations with the goal of determining the location of pheromone receptors. The receptors for the pheromones are likely located on the bases of the walking legs or on the gills, not on the pleopods, first walking legs, antennae or antennules. Shrimps are another example of organisms that use peptides generated by trypsin-like serine proteases as pheromones and signal molecules.

Size distribution and swimming activity of the sea scallop, Placopecten magellanicus, were measured in situ from high-definition video recordings collected by a remotely operated vehicle on a fished scallop bed on German Bank, Gulf of Maine in August 2010. Scallop densities ranged from 0.004 to 3.89 m−2 and shell height (SH) ranged from 16.3 to 193.8 mm. The size distribution was bimodal, with high abundance from 20 to 40 mm SH indicating a recent recruitment event in the area. The low abundance of scallops >100 mm SH was likely due to the active fishery in this area. Of 535 observed swims, 200 were characterized for swim distance, time, velocity and distance travelled per adduction. The size of scallops observed to swim ranged from 18.9 to 99.9 mm SH. Both swim time and swim distance increased linearly with SH, and quadratic relationships were observed between velocity and SH, and between distance travelled per adduction and SH. Swimming velocities peaked at ~ 50 cm s−1 for scallops between 60 and 80 mm, and maximum velocity was 103.2 cm s−1observed for an individual of 64.0 mm SH. Our study provided a unique opportunity to investigate size distribution and associated swimming activity of scallops in their natural habitat, rather than in a simulated study in the laboratory, and at depths not reachable by SCUBA diving.

In this study we examined the epibiont assemblage on shells of the living limpet Patella aspera. Limpets were collected at two sites at each of the nine islands of the Azores, totalling 707 individuals examined. Shells were measured and all the epibiota identified to the lowest taxonomic resolution possible. 190 taxa were recorded, of which 97% were algae, including 17 new records for the Azores. Only five shells were devoid of fouling organisms. The assemblage was dominated by a few algal taxa, whereas the majority of species occurred on less than 10% of the shells. A significant and positive relationship was generally found between basibiont size (shell length) and epibiota richness. The strength (slope) of the relationship, however, varied between islands and sites. These results suggest that a range of processes operating at multiple spatial scales influenced epibiont assemblages. Many features identified in these assemblages resemble, in many ways, those examined in island biogeography, suggesting that basibionts may be considered as ‘islands’ and may provide a suitable model system to test ecological hypotheses about ecosystems that are not so amenable to experimentation.

Sea urchins are key herbivores in many coastal ecosystems. The purple sea urchin, Heliocidaris erythrogramma, is widely distributed across temperate Australia where it exhibits considerable plasticity in feeding behaviour and ecophysiology. In this study we examined H. erythrogramma populations on subtidal reefs along ~4° of latitude in south-west Australia. We used a multi-factorial survey design to assess variability in H. erythrogramma abundances between locations (>200 km part), sites (≥1 km apart) and habitat types (reef flats and slopes). We also examined spatial variability in urchin size, condition (measured by gonad index), and the relative abundances of two co-occurring subspecies. Urchin densities were generally low and did not vary between locations, but did vary between habitat types and amongst sites. Site-level variability in urchin size and condition was also pronounced. The southernmost population comprised smaller individuals and greater relative abundance of the H. e. erythrogramma subspecies, which is abundant on the east coast of Australia. We observed no indication of population-level responses to a recent extreme warming event that impacted the wider ecology of the region, but further investigation into the effects of both gradual warming and short-term climatic events on the ecology of H. erythrogramma and other key herbivores is required.

Relations between fish size and otolith size of stargazer (Uranoscopus scaber) were studied in this study. A total of 268 samples were obtained from the coastal shelf of Ordu Province (south-eastern Black Sea) by commercial trawling and gillnetting operations. It was found that there were high correlations between fish size and otolith size. It was concluded that all measurable body sizes could be effectively used to estimate otolith length, width and weight. Similarly, estimation of the age of fish from otolith length and weight was also possible with high significance. The results of this research will be useful for others working on this fish, being a first study in the field. The ages of stargazer were determined between 0+ and 4+. Relationships were determined as OW = 0.001 × OWi2.76, OW = 0.35 × 10−3 × OL2.54 with high correlation coefficients of r = 0.965 and r = 0.949, respectively.

Otolith microstructure analysis was used to determine daily growth rate and hatching periods of young of the year (YOY) annular seabream, Diplodus annularis, collected by using beach seine from Çanakkale shallow waters between January and December 2007. Total length of the YOY D. annularis was between 20 and 85 mm and the daily ages ranged between 27 and 205 d. Somatic growth rate, estimated by fitting a linear regression to the age–length data set, was calculated as 0.369 mm d−1. Seasonal changes in the growth rate of the YOY D. annularis have been found to be 0.381, 0.369, 0.357 and 0.308 mm d−1 for individuals that hatched in spring, summer, autumn and winter, respectively. Analysis of covariance indicated that there were no significant differences (P > 0.05) in the growth rates between the seasons. Hatching period of the YOY D. annularis was estimated to occur between March and September, with relatively higher hatching frequency in June.