A review on mesopelagic fishes belonging to family Myctophidae

Myctophids are mesopelagic fishes belonging to family Myctophidae. They are represented by approx. 250 species in 33 genera. Called as “Lanternfishes”, they inhabit all oceans except the Arctic. They are well-known for exhibiting adaptations to oxygen minimum zones (OMZ-in the upper 2,000 m) and also performing diel vertical migration between the meso- and epipelagic regions. True to their name, lanternfishes possess glowing effect due to the presence of the photophores systematically arranged on their body, one of the important characteristic adding to their unique ecological features. Mid-water trawling is a conventional method of catching these fishes which usually accounts for biomass approx. in million tones as seen in Arabian Sea (20–100 million) or Southern ocean (70–200 million). Ecologically, myctophids link primary consumers like copepods, euphausiids and top predators like squids, whales and penguins in a typical food web. Lantern fishes become a major part of deep scattering layers (DSL) during migration along with other fauna such as euphausiids, medusae, fish juveniles, etc. Like any other marine organisms, Myctophids are susceptible to parasites like siphonostomatoid copepods, nematode larvae etc. in natural habitats. They are important contributors of organic carbon in the form of their remnants and fast sinking faeces, which get deposited on ocean beds. Economically, they are a good source of protein, lipids and minerals, which is used as fishmeal for poultry and animal feed and as crop fertilizers. Few species are considered edible, but proper processing difficulties on a higher scale limit myctophids as human food. Myctophids have a life span of approx. 1–5 years and low fecundity rates (100–2,000 eggs per spawn). This trait is a disadvantage, if continuous utilization of their population, for e.g., for fish meal industries etc., occurs without giving them a chance to revive and recover. Hence, research in this area also should be given utmost importance. In this paper, we have tried to compile information and ideas from various sources of myctophid research around the world, particularly from the Indian Ocean, to understand their ecological and economic importance and also to put forth new ideas to bring about conservation and restoration of this vulnerable resource.     

Sarcotretes (Copepoda: Pennellidae) parasitizing myctophid fishes in the Southern Ocean: new information from seabird diet

Copepods are common parasites of marine fishes, but little information is available on the biology of species that parasitize mesopelagic fishes in oceanic waters. In this study, we report the finding of large numbers of Sarcotretes spp. (n = 2340) in dietary samples of king penguins collected at Crozet and the Falklands Islands. Analysis of penguin food indicates that S. scopeli Jungersen parasitizes myctophid fishes, Protomyctophum tenisoni (Norman), in the southern Indian Ocean and P. choriodon Hulley in the southern Atlantic. It suggests that the much rarer S. eristaliformis (Brian) also parasitizes myctophids, but the host species of that copepod remains to be determined. The new data add significant information concerning the hosts and distribution of Sarcotretes spp. in the Southern Ocean and emphasize the usefulness of ichthyophagous predators in revealing valuable information on the biology of organisms that parasitize their prey.     

Late Quaternary marginal marine palaeoenvironments of northern Australia as inferred from cluster analysis of coccolith assemblages

Cluster analyses (R- and Q-mode) were applied to upper Quaternary coccolith assemblages in a sediment core (MD972132) collected in the Gulf of Carpentaria, northern Australia. This shallow gulf is influenced by the Australian monsoon, is tectonally stable and represents an important link between marine and terrestrial palaeoenvironments. The Gulf of Carpentaria is linked to the Pacific Ocean to the east by Torres Strait (12 m water depth) and to the Indian Ocean to the west by the Arafura Sill (53 m water depth), and therefore has been separated from both oceans during sea-level low-stands, resulting in the formation of Lake Carpentaria. Coccolith assemblages in the gulf are similar to modern assemblages in the region, and correspond to typical assemblages in marginal seas. The cluster analysis defines six species assemblages (R-mode), and six groups of samples (i.e., defined by depth in core depth; Q-mode), some with sub-groups, which were deposited under similar environmental conditions. We thus recognised, four major environmental facies over the past 125 ka, corresponding to closed Lake Carpentaria stages, the transitional periods while active channels sporadically connected Lake Carpentaria to the Indian Ocean, and the opening of the Gulf of Carpentaria to the ocean over either one, or both of the sills. Lake Carpentaria was isolated from both oceans through Marine Isotope Stages (MIS) 5d, MIS 4 and MIS 2, and the Gulf of Carpentaria was connected to both oceans during MIS 5c and MIS 1. Torres Strait was emergent during MIS 5b, was flooded again during MIS 5a and persisted as land bridge from MIS 4 to MIS 1. The Arafura Sill was opened from MIS 5c to MIS 5a and episodically connected the Gulf to the Indian Ocean during MIS 3.     

Assessing the contribution of foraminiferan protists to global ocean carbonate production

Larger symbiont-bearing foraminifera are prominent and important producers of calcium carbonate in modern tropical environments. With an estimated production of at least 130 million tons of CaCO(3) per year, they contribute almost 5% of the annual present-day carbonate production in the world's reef and shelf areas (0-200 m) and approximately 2.5% of the CaCO(3) of all oceans. Together with non-symbiont-bearing smaller foraminifera, all benthic foraminifera are estimated to annually produce 200 million tons of calcium carbonate worldwide. The majority of foraminiferal calcite in modern oceans is produced by planktic foraminifera. With an estimated annual production of at least 1.2 billion tons, planktic foraminifera contribute more than 21% of the annual global ocean carbonate production. Total CaCO(3) of benthic and planktic foraminifera together amounts to 1.4 billion tons of calcium carbonate per year. This accounts to almost 25% of the present-day carbonate production of the oceans, and highlights the importance of foraminifera within the CaCO(3) budget of the world's oceans.     

Influence of the Agulhas Current on the distribution of lanternfish larvae off the southeast coast of Africa

Spatial and temporal distribution patterns of lanternfish larvaealong the southeast coast of Africa were analysed in relationto oceanographic conditions. Investigations werebased on theplankton collections made during winter, spring and summer monthsof 1990–1991. The warm southward-flowing Agulhas Currentis the dominant large-scale oceanographic feature in the area.The number of species of myctophid larvae collected per cruiseranged from 35 to 38. The most abundant species differed fromone season to the other.Afew species showed marked seasonalityin their occurrence, e.g. Scopelopsis multipunclatiis only appearedin winter and Hygophum hygomii showed the highest abundancesin winter. The majority of species occurred in relatively lowconcentrations during all three periods. Relatively large concentrationsof lanternfish larvae of most species sometimes occurred veryclose inshore (especially in the north of thestudy area) inwater depths of 50–100 m. This was related to shorewardintrusions ofAgulhas Current surface water. Low numbers of larvaeof few species appeared on the inshore shelf of the southernsector of the study area, where cold central Indian Ocean wateris forced onto the shelf by kinematic upwelling.     

Widespread gene flow between oceans in a pelagic seabird species complex

Global‐scale gene flow is an important concern in conservation biology as it has the potential to either increase or decrease genetic diversity in species and populations. Although many studies focus on the gene flow between different populations of a single species, the potential for gene flow and introgression between species is understudied, particularly in seabirds. The only well‐studied example of a mixed‐species, hybridizing population of petrels exists on Round Island, in the Indian Ocean. Previous research assumed that Round Island represents a point of secondary contact between Atlantic (Pterodroma arminjoniana) and Pacific species (Pterodroma neglecta and Pterodroma heraldica). This study uses microsatellite genotyping and tracking data to address the possibility of between‐species hybridization occurring outside the Indian Ocean. Dispersal and gene flow spanning three oceans were demonstrated between the species in this complex. Analysis of migration rates estimated using bayesass revealed unidirectional movement of petrels from the Atlantic and Pacific into the Indian Ocean. Conversely, structure analysis revealed gene flow between species of the Atlantic and Pacific oceans, with potential three‐way hybrids occurring outside the Indian Ocean. Additionally, geolocation tracking of Round Island petrels revealed two individuals travelling to the Atlantic and Pacific. These results suggest that interspecific hybrids in Pterodroma petrels are more common than was previously assumed. This study is the first of its kind to investigate gene flow between populations of closely related Procellariiform species on a global scale, demonstrating the need for consideration of widespread migration and hybridization in the conservation of threatened seabirds.     

Vertical gradients in species richness and community composition across the twilight zone in the North Pacific Subtropical Gyre

Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0–1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology‐based studies in the region (4,024 OTUs, 10‐fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic–upper mesopelagic depths (100–300 m), with slight shoaling of maximal richness at night due to diel vertical migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies. Four distinct depth‐stratified species assemblages were identified, with faunal transitions occurring at 100 m, 300 m and 500 m. Highest diversity occurred in the smallest zooplankton size fractions (0.2–0.5 mm), which had significantly lower % OTUs classified due to poor representation in reference databases, suggesting a deep reservoir of poorly understood diversity in the smallest metazoan animals. A diverse meroplankton assemblage also was detected (350 OTUs), including larvae of both shallow and deep living benthic species. Our results provide some of the first insights into the hidden diversity present in zooplankton assemblages in midwaters, and a molecular reappraisal of vertical gradients in species richness, depth distributions and community composition for the full zooplankton assemblage across the epipelagic, mesopelagic and upper bathypelagic zones.     

Biofuels in China: opportunities and challenges

With rapid economic development, energy consumption in China has tripled in the past 20 yr, exceeding 2.4 billion tons of standard coal in 2006. The search for new green energy as substitutes for the nonrenewable energy resources has become an urgent task. China has a variety of climates and is rich in potential biofuel plant species. Corn and cassava are used as the main raw materials for bioethanol production in China. At the end of 2005, bioethanol productivity had increased to 1.02 million tons produced by four companies, and bioethanol-blended petrol accounted for 20% of the total petrol consumption in China. According to the Mid- and Long-term Development Plan for Renewable Energy, the consumption of biodiesel in China will reach 0.2 million tons in 2010 and 2.0 million tons in 2020. This review is intended to provide an introduction to the distribution and development of biofuel crops and biofuel industry in China.     

Features of species composition and abundance of the nekton community in the upper epipelagic layer of the Northwest Pacific in early summer

The composition and structure of nekton in the upper epipelagic zone is considered based on the data of trawl surveys conducted in the Northwestern Pacific Ocean and adjacent waters in 2004–2009. Alterations in the nekton community during the early summer period, as well as peculiarities of its species composition and quantitative distribution that depend on changes in background conditions are described. In total, as many as 66 species of fish and 22 species of cephalopods were recorded in catches for the studied period. The lowest biodiversity was found in the near-shore waters (areas nos. 5, 7, and 9) and the highest one was in open oceanic waters (area no. 13). In 2004–2009, nekton biomass was formed mainly by mesopelagic species and their share amounted to 40–60% of the entire nekton community. Pacific salmon varied within 17–37% the total nekton biomass in various years. In general, for the period of studies, the mean biomass of nekton community was 2 431 000 tons, and in 2009, the total biomass approached this value.     

The occurrence of Pampus argenteus (Euphrasen, 1788), (Osteichthyes, Perciformes, Stromateoidei, Stromateidae) in the North Sea

The occurrence in the North Sea of a specimen of the white pomfret, Pampus argenteus (Euphrasen, 1788), a mesopelagic fish which is native to the Indian Ocean and particularly South-east Asia and the East China Sea, is described. Other anomalous distribution records for the same species are examined and some possible explanations investigated.     

Length-weight relationship of coral reef-associated fishes from Gulf of Mannar and Palk Bay,Southeast Coast of India

Length-weight relationship parameter was estimated for eight coral reef-associated finfish species from the Gulf of Mannar and Palk Bay, Eastern Indian Ocean. Fish samples were collected from the landings of trawlers with a cod-end mesh size of 25–35 mm, operated at a depth ranging from 50–70 m off Tuticorin, Rameswaram and Thondi coasts on monthly basis between June-2018 and July-2019. Fish specimens were sampled by measuring total length (TL) and total weight (TW) with precision to 0.1 cm and 0.1 g respectively. A new maximum total length was recorded for Canthigaster solandri, Centriscus scutatus and Halichoeres stigmaticus from this study.     

Feeding habits of the blue shark, Prionace glauca, and salmon shark, Lamna ditropis, in the transition region of the Western North Pacific

We describe the feeding habits of 70 blue sharks (Prionace glauca) and 39 salmon sharks (Lamna ditropis) caught at 0–7 m depth at night by research drift gillnets in the transition region of the western North Pacific during April–May of 1999 and 2000. Blue sharks of 50–175 cm total length fed on a large variety of prey species, consisting of 24 species of cephalopods and 16 species of fishes. Salmon sharks of 69–157 cm total length fed on a few prey species, consisting of 10 species of cephalopods and one species of fish. Important prey for the blue sharks were large, non-active, gelatinous, meso- to bathypelagic cephalopods (e.g., Chiroteuthis calyx, Haliphron atlanticus, Histioteuthis dofleini and Belonella borealis) and small myctophid fishes. Important prey for the salmon sharks were mid-sized, active, muscular, epi- to mesopelagic squids (e.g. Gonatopsis borealis, Onychoteuthis borealijaponica and Berryteuthis anonychus). Our results suggest that blue sharks feed on cephalopods mainly during the daytime when they descend to deep water. Salmon sharks may feed opportunistically with no apparent diurnal feeding period. Blue sharks and salmon sharks have sympatric distribution in the transition region in spring; they have different feeding habits and strategies that reduce competition for food resources.     

Jute—World’s foremost bast fibre. I. Botany,agronomy, diseases and pests

India and Pakistan together contain over 96% of the world’s acreage devoted to this crop and produce nearly 97% of the world’s total supply. Two species of Corchorus are involved. The production of fibre has increased from about one million tons at the beginning of the present century to about two million tons today.     

Breaking the ice: large-scale distribution of mesozooplankton after a decade of Arctic and transpolar cruises

Mesozooplankton collected during five summer expeditions to the Arctic Ocean between 1987 and 1991 was analysed for regional patterns in biomass and species distribution, distinguishing between an epipelagic (0–100 m) and a deeper (0–500 m) layer. A total of 58 stations was sampled mainly in the Nansen, Amundsen and Makarov Basins of the central Arctic Ocean and in areas of the Greenland Sea, West Spitsbergen Current and Barents Sea. Results from the different expeditions were combined to create a transect extending from the Fram Strait across the Eurasian Basin into the Makarov Basin. Mesozooplankton dry mass in the upper 500 m decreased from 8.4 g m⁻² in the West Spitsbergen Current to less than 2 g m⁻² in the high-Arctic deep-sea basins. In the central Arctic Ocean, biomass was concentrated in the upper 100 m and was dominated by the large copepods Calanus hyperboreus and C. glacialis. In contrast, the mesozooplankton in the West Spitsbergen Current was more evenly distributed throughout the upper 500 m, with C. finmarchicus as the prevailing species. The distribution of abundant mesopelagic species reflected the hydrographic regime: the calanoid copepod Gaetanus tenuispinus and the hyperiid amphipod Themisto abyssorum were most abundant in the Atlantic inflow, while Scaphocalanus magnus was a typical component of the high-Arctic fauna. The relatively high mesozooplankton biomass and the occurrence of boreal-Atlantic species in the central Arctic Ocean are indicators for the import of organic material from allochthonous sources, especially from the northern North Atlantic. Hence, in spite of its enclosure by land masses, the Arctic Ocean is characterized by an exchange of water masses and organisms with the North Atlantic, and advection processes strongly influence the distribution of plankton species in this high-latitude ecosystem. Received: 18 December 1997 / Accepted: 11 April 1998     

Distribution and abundance of fish larvae in the northern Ionian Sea (Eastern Mediterranean)

The purpose of this paper was to study the spatial distribution, abundance and composition of fish larvae in the northern Ionian Sea. Samples were collected to the 600 m depth with an electronic multinet BIONESS during the “INTERREG Italia-Grecia” oceanographic cruise carried out in March 2000 off the Apulian Italian coast. A total of 46 species of teleost early stages were collected, belonging to 38 genera and 22 families. Over 52% of the larvae identified were mesopelagic species, almost 27% were demersal and about 21% pelagic. A total of 307 myctophids, 69 clupeids and 61 gadid post-larvae dominated the community. Benthosema glaciale (mean 6.1 mm SL) was the most abundant species (21.6%), the most frequent in the samples (28.8%), and dominant in the whole study area (mean 1.4 ind/100 m³). Particular attention was given to the horizontal and vertical distribution and abundance of the three dominant post-larval species: Benthosema glaciale, Sprattus sprattus sprattus and Notoscopelus elongatus. The Pearson coefficient (R = 0.734) showed a high correlation between total zooplankton and fish larval assemblages in terms of spatial distribution abundance values. Regarding the vertical distribution of fish larvae, Sorensen’s index (S = 0.69) showed that fish larvae and total zooplankton abundance peaks co-occurred along the water column.     

The fatty acids of some marine teleosts

The lipids of five mesopelagic species of myctophid, two mesopelagic species of stomia-toid, and one epipelagic species of Macrorhamphosidae from the eastern-North Atlantic have been examined by thin-layer chromatography and their fatty acid compositions have been determined by gas-liquid chromatography.     

Antarctic Marine Biodiversity – What Do We Know About the Distribution of Life in the Southern Ocean?

The remote and hostile Southern Ocean is home to a diverse and rich community of life that thrives in an environment dominated by glaciations and strong currents. Marine biological studies in the region date back to the nineteenth century, but despite this long history of research, relatively little is known about the complex interactions between the highly seasonal physical environment and the species that inhabit the Southern Ocean. Oceanographically, the Southern Ocean is a major driver of global ocean circulation and plays a vital role in interacting with the deep water circulation in each of the Pacific, Atlantic, and Indian oceans. The Census of Antarctic Marine Life and the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCAR-MarBIN) have strived to coordinate and unify the available scientific expertise and biodiversity data to improve our understanding of Southern Ocean biodiversity. Taxonomic lists for all marine species have been compiled to form the Register of Antarctic Marine Species, which currently includes over 8,200 species. SCAR-MarBIN has brought together over 1 million distribution records for Southern Ocean species, forming a baseline against which future change can be judged. The sample locations and numbers of known species from different regions were mapped and the depth distributions of benthic samples plotted. Our knowledge of the biodiversity of the Southern Ocean is largely determined by the relative inaccessibility of the region. Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work. Taxa such as mollusks and echinoderms are well represented within existing datasets with high numbers of georeferenced records. Other taxa, including the species-rich nematodes, are represented by just a handful of digital records.     

Paleoceanographic changes during the past 1.9 Myr at DSDP Site 238, Central Indian Ocean Basin: Benthic foraminiferal proxies

Deep-sea benthic foraminifera have been quantitatively analyzed in samples (> 125 μm size fraction) from Ocean Drilling Program (ODP) Site 238, to understand paleoceanographic changes in the Central Indian Basin over the past 1.9 Myr. Factor and cluster analyses of the 25 highest-ranked species made it possible to identify five biofacies, characterizing distinct deep-sea environmental settings. The environmental interpretation of each biofacies is based on the ecology of recent deep-sea benthic foraminifera. The benthic faunal record indicates fluctuating deep-sea conditions in environmental parameters including oxygenation, surface productivity and organic food supply. These changes appear to be linked to Indian summer monsoon variability, the main climatic feature of the Indian Ocean region. The benthic assemblages show a major shift at ∼ 0.7 to 0.6 Ma, marked by major turnovers in the relative abundances of species, coinciding with an increased amplitude of glacial cycles. These cycles appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the Central Indian Ocean Basin.     

应用年龄结构产量模型评估印度洋黄鳍金枪鱼资源

利用年龄结构产量模型(Age structured production model,ASPM)评估了印度洋黄鳍金枪鱼资源状况,同时结合亲体量-补充量曲线陡度系数和年龄组自然死亡系数的敏感性分析,描述了黄鳍金枪鱼资源的发展趋势、判断了开发状况。研究认为,陡度系数设在0.6-0.8才可能使亲体量产生出最大可持续产量(Maximum sustainable yield,MSY)的水平。采用美洲热带金枪鱼委员会推荐的自然死亡系数值时,评估结果最接近渔业现状。研究发现,随着捕捞努力量的增加,总资源量和亲体量呈逐年下降趋势,但总资源量自1990年后趋向稳定,维持在195.9-263.2万t,平均为221万t;亲体量在1994年后下降到100万t以下,1997年以后处在维持MSY所需亲体量的水平之下,目前仍呈下降趋势。补充量在渔业初期呈现大幅度波动,1978年后趋于稳定,并维持在3258.36-6583.35×106尾,平均为4687.66×106尾。未成熟鱼的数量总体较为稳定,但成熟鱼的数量出现剧减,从渔业初期的246.51×106尾减少到2005年的19.02×106尾。模型估计的总捕捞死亡系数从渔业初期开始逐渐上升,1991年后出现大幅度上升,处于0.334-0.456间,2003年时超过FMSY,捕捞产量也于2003年超过MSY。分析认为,2003年以来印度洋黄鳍金枪鱼的持续高产量被认为是不可持续,根据ASPM估算,2003-2006年均产量46.4万t,超过了MSY(36.4万t);S/SMSY为0.76;Fall/FMSY为1.39,由此判断现阶段印度洋黄鳍金枪鱼正处于过度捕捞状态。     

Late Quaternary marginal marine palaeoenvironments of northern Australia as inferred from cluster analysis of coccolith assemblages

Cluster analyses (R- and Q-mode) were applied to upper Quaternary coccolith assemblages in a sediment core (MD972132) collected in the Gulf of Carpentaria, northern Australia. This shallow gulf is influenced by the Australian monsoon, is tectonally stable and represents an important link between marine and terrestrial palaeoenvironments. The Gulf of Carpentaria is linked to the Pacific Ocean to the east by Torres Strait (12 m water depth) and to the Indian Ocean to the west by the Arafura Sill (53 m water depth), and therefore has been separated from both oceans during sea-level low-stands, resulting in the formation of Lake Carpentaria. Coccolith assemblages in the gulf are similar to modern assemblages in the region, and correspond to typical assemblages in marginal seas. The cluster analysis defines six species assemblages (R-mode), and six groups of samples (i.e., defined by depth in core depth; Q-mode), some with sub-groups, which were deposited under similar environmental conditions. We thus recognised, four major environmental facies over the past 125 ka, corresponding to closed Lake Carpentaria stages, the transitional periods while active channels sporadically connected Lake Carpentaria to the Indian Ocean, and the opening of the Gulf of Carpentaria to the ocean over either one, or both of the sills. Lake Carpentaria was isolated from both oceans through Marine Isotope Stages (MIS) 5d, MIS 4 and MIS 2, and the Gulf of Carpentaria was connected to both oceans during MIS 5c and MIS 1. Torres Strait was emergent during MIS 5b, was flooded again during MIS 5a and persisted as land bridge from MIS 4 to MIS 1. The Arafura Sill was opened from MIS 5c to MIS 5a and episodically connected the Gulf to the Indian Ocean during MIS 3.