Bathyal cumaceans of the Catalan Sea (North-western Mediterranean): faunistic composition,diversity and near-bottom distribution along the slope (between 389 and 1859 m)

Deep-water epibenthic/suprabenthic species of Cumacea were studied in the Catalan Sea (Western Mediterranean). Samples (21) were taken at depths from 389 to 1859m, using a Macer-GIROQ type sledge, 32 cumacean species were collected. Diastyloides serratus and Leucon longirostris were the commonest species on the upper slope and middle slope, respectively. On the lower slope (1250–1859 m) dominance by any single species was not apparent and Cyclaspis longicaudata, Procampylaspis bonnieri and Platysympus typicus were the most abundant species. Two leuconids (Leucon cf. serratus, and Leucon (Crymoleucon) sp. A) were recorded for the first time in the Mediterranean Sea. The highest total abundance of cumaceans was encountered over the middle slope. Highest values of species richness and diversity (H') were registered at intermediate depths on the lower slope (1250–1355 m). The low H' value on the middle slope was attributable to the dominance of L. longirostris. Swimming coefficients calculated from near-bottom samples revealed intraspecific differences in the most abundant species. Thus, while mancas, juveniles, immature males and females, and adult females were captured almost exclusively in the lower level of the sledge, adult males of L. longirostris swam in the water column indistinctly between 10 and 140cm above the bottom. Similar trends, although less evident, have been established for other deep-sea cumaceans.     

Seasonal cycle of zooplankton abundance and biomass in Hamsilos Bay,Sinop, Southern Black Sea,Turkey

In this investigation, zooplankton was studied between July 2015 and June 2016 in Hamsilos Bay to examine spatial and temporal variations in abundance, biomass and taxonomic composition. The recorded mean zooplankton abundance and biomass were 3770.35 ind. m^?3 and 25.06 mg m^?3 in the inner station, 3928.11 ind. m^?3 and 28.19 mg m^?3 in the middle station and 3948.22 ind. m^?3 and 28.74 mg m^?3 in the outer station, respectively. The high abundance and biomass values observed in September 2015 were attributed to Oithona davisae (4575 ind. m^?3 at the inner station) and Penilia avirostris (33.4 mg m^?3 at the outer station), respectively. Copepoda was the most abundant during the entire period of the survey. In terms of abundance and biomass, Copepoda was followed by meroplankton and Cladocera. Most species within the zooplankton community exhibited evident seasonality throughout the year in Hamsilos Bay. This was particularly apparent for O. davisae, Centropages ponticus, Cladocera and meroplankton, which were abundant in summer–autumn, and for Pseudocalanus elongatus, which was more abundant during winter and spring. It has been determined that O. davisae, which is a non-indigenous cyclopoid copepod species of the Black Sea, has successfully inhabited southern Black Sea and has established a permanent population in this area.     

The carcinofauna found in stomach contents of the flying gurnard (Dactylopterus volitans) on the continental shelf of the Campos Basin,Brazil

A total of 3109 crustaceans belonging to 50 taxa distributed in 42 families were found in 117 analysed stomachs of flying gurnard (Dactylopterus volitans). Samples were obtained in April 2008 by the R/V Gyre using a bottom trawl towed in 12 stations at 14–100 m depth on the continental shelf of the Campos Basin, Brazil. The carcinofauna was analysed and the order Calanoida (Copepoda) found to be the most important item in terms of relative abundance and frequency of occurrence, followed by the order Amphipoda (Peracarida), the infraorder Brachyura (Decapoda), the order Stomatopoda and the subclass Myodocopa (Ostracoda). In the order Calanoida, the species Pontellopsis cf. villosa (Pontellidae) represented 98.04% of total crustacean abundance. The diet of Dactylopterus volitans varied according to fish size, with higher diversity of Crustacea at smaller size classes, decreasing in larger fishes. A similar pattern regarding depth was obtained, with greater diversity of taxa in gurnard stomachs caught at shallower depths. Flying gurnard is considered a generalized carnivore of invertebrates, eating mobile macrobenthic organisms, such as crustaceans, and its diet varies with its life stage, without any specific group as its main food source.     

Relating abundance of purpleback flying squid Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae) to environmental parameters using GIS and GAM in south-eastern Arabian Sea

The distribution pattern of purpleback flying squid and the relationship between its abundance and environmental variables in the south-eastern Arabian Sea were analysed using a geographical information system (GIS) and a generalised additive model (GAM). Highest abundances were observed during December and January within 10 and 13°N and 71 and 72°E around the Lakshadweep Islands. The mean abundance in the area was 4.21 tonnes/km² and the maximum sustainable yield (MSY) was estimated as 0.63 million tonnes. GAM indicated that very high squid abundance was associated with low values of dissolved oxygen (6.01–6.27 mg/L), sea surface temperature (28.03–28.62°C), pH (7.75–8.56), salinity (30.42–34.48 psu), chlorophyll-a (0.4–0.6 mg/m³), zooplankton biomass (0.23–0.64 mL/m³), and shallow 20°C isotherm (101.2–134.7 m) and mixed layer depth (17.8–29.8 m). As a carnivore from paralarval stages, S. oualaniensis depends on secondary and tertiary production to sustain its population for which primary production is used up. In the tropical Arabian Sea where temperature differences are not so pronounced, S. oualaniensis distribution was found to be related to a low but very narrow sea surface temperature (SST) band. There is sufficient fishable biomass in the area to possibly launch a new targeted oceanic squid fishery from the western seaboard of India.     

In situ observations on behaviour of the ommastrephid squid genus Illex (Cephalopoda: Ommastrephidae) in the northwestern Atlantic

We compiled observations of ommastrephid squid of the genus Illex, primarily Illex illecebrosus from archived submarine video footage recorded during dives off Cape Hatteras and New England, and in the Gulf of Mexico. Based on the behaviour observed, we derived a partial in situ ethogram, or catalogue of the body patterns and behaviour. In total, 36 components were observed: 16 chromatic components (5 light and 11 dark), 10 postural components and 10 locomotor components. Co-occurrence analyses were used to show that specific sets of components occurred together either more or less often than they would if chosen at random. In addition, some of the components were observed occurring during specific behaviours, such as bottom sitting, hunting, or schooling. Such observations by submersibles also provide very precise, although incomplete, records of depth distribution. We summarize the depths and altitudes above bottom of these observations by time of day. Most of the squid were observed near bottom at depths of about 200–900 m. The deepest depths observed were during daytime and the shallowest during the evening. However, individuals were observed as much as 1000 m above the bottom during daytime whereas others were on or near the bottom in deep water during the evening.     

Deep-water amphipods from the Catalan Sea slope (western Mediterranean): Bathymetric distribution,assemblage composition and biological characteristics

Deep-water epibenthic/suprabenthic species of Amphipoda were studied in the Catalan Sea (north-western Mediterranean) at depths from 389 to 1859 m. In four cruises 20 samples were effected during 1991–1992, covering four different seasonal periods (March, April, July and December). A minimum total of 82 species was collected. Ampelisca uncinata and Eusirus leptocarpus were newly recorded as components of the Mediterranean fauna while three other species collected (Bathymedon sp. A, Autonoe sp. and Rhachotropis cf. gracilis) had distinct possibilities to be new species. The Gammaridae Carangoliopsis spinulosa and the Oedicerotidae Synchelidium maculatum were the two main dominant species on the upper slope level (389-506 m). On the middle slope (between 549-601 m), dominance by any few species was not apparent; the Eusiridae Rhachotropis glabra and R. caeca together with Bathymedon acutifrons, Scopelocheirus hopei and Andaniexis mimonectes were the most abundant species. On the lower slope, at depth below 1000 m, R. caeca was the largely dominant species. The highest species richness (S_T) was reported at intermediate depths over the middle slope (63 species), decreasing with depth increase, and being particularly low at 1808–1859 m (19 species). Total amphipod densities were also higher at the upper and middle slope levels (1760.2–2613.9 amphipods/1000 m³) than below 1000 m (376.4–679.2 amphipods/1000 m³). The low swimming coefficients (K_t) of bathyal Gammaridea, ranging between 0 and 0.336, indicate their relationship to the water-sediment interface although interespecific differences in K_t in relation to species size were also reported. Almost all the dominant amphipods had recruits (=smallest juveniles) in two or three of the three seasons sampled (mainly in March and December), and the smallest juveniles were often only abundant in two of these seasons. This indicates that most species had more than one generation per year, probably suggesting bivoltinism, a commonly adopted biological strategy among intertidal, littoral and shallow water amphipods, as the commonest strategy adopted by the mid-bathyal amphipods in our study.     

Population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) in the northern Aegean Sea (NE Mediterranean)

The population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) were studied in the northern Aegean Sea in samples collected annually (1997–2000) in summer, through experimental trawl, at depths down to 600 m. Females were larger than males in Plesionika martia and Plesionika heterocarpus; no significant differences in size of males and females were found in Chlorotocus crassicornis and Plesionika antigai. A trend of increasing size with depth was observed, as well as a linear increase in the proportion of females with increasing size. Sex ratio was skewed towards females at all depths in P. antigai, while in P. heterocarpus and C. crassicornis males dominated the intermediate depths. Negative allometries were apparent in the carapace length–weight relationships in males of all species. Isometric relationships were found in females apart from in P. heterocarpus. The population patterns conform to relevant Mediterranean reports. However, some population differences exist that may reflect the distinct environmental conditions prevailing in the study area.     

Annelids (Polychaeta and Oligochaeta) from the Sea of Marmara,with descriptions of five new species

This paper deals with annelids (Oligochaeta and Polychaeta) collected in the Sea of Marmara between 2006 and 2010 at depths from 0 to 66 m. A total of five oligochaete and 198 polychaete species were found. Five polychaete species, namely Prosphaerosyllis marmarae sp. nov., Levinsenia demiri sp. nov., Levinsenia kosswigi sp. nov., Levinsenia marmarensis sp. nov. and Levinsenia tribranchiata sp. nov. are new to science, and five oligochaete and 84 polychaete species are new to the fauna of the Sea of Marmara. A list of species found in the region and their maximum densities are presented at depth intervals. The present material includes six alien polychaete species, Paraprionospio coora, Polydora cornuta, Prionospio (Minuspio) pulchra, Pseudopolydora paucibranchiata, Chaetozone corona and Metasychis gotoi, of which the latter four species were new records for the region.     

First observation and seasonal dynamics of the new invasive planktonic copepod Oithona davisae Ferrari and Orsi, 1984 along the southern Black Sea (Anatolian Coast)

The zooplankton species Oithona davisae is indigenous to coastal areas of Japan and the China Seas. It has, however, successfully invaded many other coastal marine regions such as San Francisco Bay, the Mediterranean Sea, the North Sea and the Black Sea. It is transported most probably in ballast water tanks. This is the first report of O. davisae in the coastal regions of the southern Black Sea (Anatolian coast). Based on monthly plankton sampling at two stations (Sürmene Bay), the seasonal dynamics of O. davisae were investigated. The highest abundance occurred at the coastal station (49,761 ind. m^?3) in December and in October at the offshore station (8896 ind. m^?3). The egg-carrying copepod O. davisae is more abundant in September (4571 ind. m^?3) at the coastal station and in August (952 ind. m^?3) at the offshore station. Expansion of this invasive copepod along the Black Sea coasts is reported by another country also. According to our results this invasive species may replace its native congener, Oithona nana. It can be hypothesized that O. davisae is one of the key species for energy transfer to the upper level of the food web from the microbial loop, which has recently become important in the Black Sea.     

First records of dendrobranchiate prawns (Decapoda: Dendrobranchiata) from the Andaman Sea,India

ABSTRACT

The Andaman Sea adjoining the Indian Territory is biologically rich in terms of marine diversity. However, inadequate surveys during the post-independence era have resulted in large lacunae in data on the species composition in these waters. In this paper, we report the first observation of two species of dendrobranchiate prawns, Metapenaeopsis difficilis Crosnier, 1991 and Haliporus taprobanensis Alcock and Anderson, 1899, in the Indian seas, supplemented with notes on their morphological diagnoses, comparison with closely related species and zoogeographical distribution. Crustacean specimens were collected using trawl nets and a naturalists’ dredge on board the Fisheries Oceanography Research Vessel Sagar Sampada in the deeper offshore region between 124 and 850 m depth in the Andaman Sea during the period 2015–2017. Metapenaeopsis difficilis is distinguished by an oval-shaped thelycal plate and a low, unarmed bead-like plate on the thoracic sternum between the third pereiopods. Metapenaeopsis difficilis is previously reported from the Philippines, Indonesia, Coral Sea, New Caledonia, Marquesas Islands, and Wallis and Futuna Islands at depths between 21 and 440 m, thereby indicating its westward range extension. Haliporus taprobanensis is distinguished by a tough integument, presence of a postero-dorsal spine on the fourth pleonal somite, and smooth dorsum of the first four pleonal somites. Haliporus taprobanensis is previously reported from South Africa, Madagascar, off Sri Lanka, Indonesia, Philippines and northern Australia at depths between 300 and 1650 m.     

Deep-living demersal fishes in the Catalan Sea (western Mediterranean) below a depth of 1000 m

An extensive survey of the deep-living fishes of the Catalan Sea (western Mediterranean) recorded 31 species in 19 families and 29 genera from 100 samples at depths between 960 and 2251 m. Chlorophthalmidae, Moridae and Macrouridae accounted for nearly 85% of all specimens taken. In biomass terms, Hexanchidae, Moridae, Alepocephalidae and Chlorophthalmidae were the most important families. A quantitative model of the bathymetric distribution of the species is presented. The ‘centre of gravity’ of species’ distribution and the habitat width, a measure of the distribution heterogeneity, are also given. Out of the 31 demersal species caught, the distributions of only 13 are centered below 1000 m. The Mediterranean deep-sea ichthyofauna is very impoverished in comparison with the adjacent Atlantic Basin fauna.     

Effect of tropical monsoon on fishery abundance of Indian squid (Uroteuthis (Photololigo) duvaucelii)

Indian squid, Uroteuthis (Photololigo) duvaucelii (Loliginidae) constitute an important component of the inshore cephalopod fisheries along the eastern Arabian Sea. Local environmental variation plays an important role in species–environment interactions in neritic squids, which inhabit nearshore/coastal waters. Such ‘active’ and ‘passive’ responses of squids to environmental changes is crucial in understanding their relationships and influence on the biological processes, distribution and abundance of the fast-growing short-lived coastal loliginids. The empirical relationship between squid abundance and the variability in rainfall and sea surface temperature (SST) were explored in a tropical monsoon fishery. Monthly catch rates (catch per fishing hour) of squids in commercial trawl during 1987–2009 were used as the abundance index. Linear regression models with ARIMA errors were fitted with catch per unit hour time series as dependent variable and rainfall and SST as exogenous variables. While rainfall was observed to have a negative effect on squid abundance, the SST recorded a positive impact. ARIMA models provided satisfactory fit to observed data and forecast of 22 months. Given that the squid life-cycle is a function of their environment, this result is relevant in forecasting squid biomass for the management of tropical monsoon fisheries.     

Hybridization of beaked redfish (Sebastes mentella) with small redfish (Sebastes viviparus) and diversification of redfish (Actinopterygii: Scorpaeniformes) in the Irminger Sea

We searched for Sebastes mentella and Sebastes viviparus hybrids in samples of redfish with external traits typical of S. mentella. The samples were collected in the Irminger Sea in 2007 (n = 131) and 2010 (n = 72). Hybrids were identified using MDH-2* locus coding malate dehydrogenase. Both samples contained hybrids (two and one individuals, respectively). The results of our investigations and previously published data show that interspecific hybridization may have a strong impact on the genetic structure of S. mentella in the Irminger Sea, presumably being one of the main reasons for the differentiation of allele frequencies of some genes between samples collected at different depths. This should be taken into consideration in studies of Irminger Sea redfish.     

Environmental humidity and leaf-litter depth affecting ecological parameters of a leaf-litter frog community in an Atlantic Rainforest area

We studied a leaf-litter frog community from an Atlantic Rainforest area in the state of Espírito Santo, south-eastern Brazil. Frogs were sampled using 4 × 4-m plots. We recorded 348 individuals from 13 species. The estimated overall density of leaf-litter frogs in the study area was 6.6 frogs/100 m² with an estimated overall frog biomass of 0.04 g/ha. Brachycephalus didactylus was the species with the highest estimated density and highest abundance. Five of the litter frog species recorded are considered endemic to the Atlantic Forest and two species are endemic to the state of Espírito Santo, including Euparkerella robusta, which is considered threatened as the result of habitat loss. The overall abundance of leaf litter was positively related to relative humidity and depth of the leaf litter. The relationship between frog body mass and frog abundance was significant, suggesting that a general biological trend in this relationship occurs in our study area.     

Growth ‘rules’ and the larvae of decapod crustaceans

Summary

Statements that have attempted to express the relationship between the sizes of successive arthropodan instars are examined with reference to published data on larval decapod crustaceans.

The conclusions reached are (a) that ‘Brooks's Law’, which simply states that the lengths of successive instars form an exponential series, generally holds good in decapod larvae, (b) that ‘Przibram's Rule’, stating that the weight increase between instars is always by some power of 2, is not supported by the observed length changes, and (c) that Gurney's suggestion that growth factors in decapod larvae do not normally exceed about 1·5 is not applicable to the order as a whole, but may be valid for some sub-groups within it.     

Spatial distribution of ichthyofauna in the northern Alboran Sea (western Mediterranean)

This study describes the four main demersal fish assemblages identified along the continental shelf and slope (30–800 m depth) of the northern Alboran Sea (western Mediterranean), based on the analysis of the MEDITS (International bottom trawl survey in the Mediterranean) 12-year data series. We collected 186 fish species belonging to three classes, 24 orders and 69 families. Taxonomically, the order Perciformes was the most diverse, represented by 18 families and 58 species. Each assemblage had particular characteristics of abundance, biomass, mean fish weight and species richness. The geographical differences associated with the distribution of some species occurred within shelf assemblages. The middle slope was characterised by the highest similarity between samples, probably due to its lower environmental variability compared to that of the other assemblages.     

Decapod crustaceans of the Delaware Bay area

Summary

Based on samples from 1968 to 1976 with a variety of collecting gear, 37 species belonging to 18 families of decapod crustaceans are reported from the Delaware Bay area. The species are divided into four major groups based on life habit and/or habitat (nektonic, benthic, commensal, and semi-terrestrial) and their distribution, relative abundance, and general ecology are described. It is concluded that the decapod crustaceans have closer affinities with taxa from the cool end of the Virginian province. Moreover, it is also concluded that our list is a conservative number of species because most collecting was conducted with grabs as dredge hauls which were primarily restricted to river oyster beds.