Harpacticoida (Crustacea: Copepoda) of the South China Sea: faunistic and biogeographical analysis

Based on original and on published databases, a compendium of the Harpacticoida of the South China Sea is presented, and the distributional range of species is discussed. Up to now, a total of 77 harpacticoid species belonging to 57 genera and 19 families have been recorded in this region. Twenty of these species, collected in Nha-Trang Bay (Vietnam), have not hitherto been described. The most speciose families are the Miraciidae (20 species) and the Laophontidae (9 species). Thirteen families were represented by one to three species only and six families by four to seven species. A brief comparison is presented between the harpacticoid fauna of the South China Sea, the Philippine Islands, the inner Malayan Archipelago (Java, Flores, Banda, and Celebes Seas), New Guinea, the Yellow Sea, and the Andaman and Nicobar Islands. The overall similarity between the species lists of these areas was observed to be extremely low (average value of Simpson index is 0.15 ± 0.08). The lists of planktonic species from the different areas showed the highest similarity. The lowest similarity (highest endemism) was observed between the lists of interstitial species. It is likely that one of the factors determining the differences between the faunas is the poor knowledge about the composition and distribution of benthic harpacticoids in tropical latitudes.     

Glaciella,a new genus of freshwater Canthocamptidae (Copepoda,Harpacticoida) from a glacier in Nepal,Himalayas

A new genus and new species of Canthocamptidae: Glaciella yalensis (Copepoda: Harpacticoida) from the surface of Yale Glacier, Nepal is described. This new species was collected from cryconite-pit on the surface of the glacier and is closely related to genus Maraenobiotus, but easily distinguishable from its species in the following: 1) segments and setae on endopodites of legs 2–4 in the male differing shape, 2) exopodites of male legs 3–4 with modified setae, 3) caudal seta in female absent. Body color of this copepod is red in live specimens.Contributions No. 86 Itako Hydrobiological Station, Ibaraki University.     

三亚岩相潮间带底栖海藻群落结构及其季节变化

为了解三亚潮间带大型海藻生态现状,布设6条岩相断面,于2008年1—11月进行了四季野外的调查,并使用物种多样性指数与聚类分析研究了潮间带大型海藻四季的群落结构和多样性变化。调查共鉴定出大型底栖藻类130种,隶属于4门75属,其中红藻门41属67种、褐藻门16属31种、绿藻门15属29种、蓝藻门3属3种。潮间带海藻种类数季节变化不大,并呈低潮带>中潮带>高潮带的垂直分布特征,且中低潮带有共同分布种,夏季尤为普遍。潮间带海藻夏冬两季平均生物量高于春秋两季,但并无显著差异。优势种季节变化明显:春季有波利团扇藻Padina boryana、日本仙菜Ceramium japonicum、半叶马尾藻Sargassum hemiphyllum、海柏Polyopes polyideoides,夏季有波状软凹藻Chondrophycus undulates、冠叶马尾藻Sargassum cristaefolium、宽扁叉节藻Amphiroa dilatata、石花菜Gelidium amansii,秋季有冠叶马尾藻、波状软凹藻、叶状铁钉菜Ishige foliacea,冬季有瓦氏马尾藻Sargassum vachellianum、苔状鸭毛藻Symphyocladia marchantioides、珊瑚藻Corallina officinalis、波利团扇藻、日本仙菜。群落多样性冬高夏低:Shannon多样性和Margalef丰富度指数最大值出现在冬季,Shannon多样性和Pielou均匀度指数最低值出现在夏季。区域底栖藻类以暖水性热带-亚热带种为主,其次为温水性的暖温带种类,基本符合南海南区暖水区系特点。研究表明,尽管三亚潮间带底栖海藻种类数与生物量上并无显著的季节差异,但群落结构与多样性均显示出一定的季节变化。     

The biology and ecology of lotic microcrustaceans

• 1 Copepoda, Ostracoda and ‘Cladocera’ are important meiobenthic Crustacea which can be both numerically abundant and species rich in running waters. Harpacticoids and ostracods are well adapted to benthic life because they are typical crawlers, walkers, and burrowers. Many cladocerans are substratum dwellers, but most benthic species among these can also swim. Cyclopoids which are generally good swimmers are nevertheless often bottom frequenters and actively colonise sediment interstices (the hyporheic zone).
  • 2 The subclass Copepoda includes 10 orders. With 53 families, the order Harpacticoida dominates the benthos. Only five of these families are represented in fresh waters (ca. 1 000 species and subspecies). The order Cyclopoida includes 12 families of which the Cyclopidae is well represented in freshwater habitats with 900 species and subspecies. Freshwater Ostracods belong to the order Podocopida (5 000 species) with three superfamilies occurring in running fresh waters. The group ‘Cladocera’ contains four orders, 12 families, more than 80 genera, and 450–600 freshwater species. Most of the benthic species are found in the families Chydoridae (39 genera), Macrothricidae, Ilyocryptidae and Sididae.
• 3 For each of the three major taxa, morphological characteristics are presented, specimen collection and preparation are described and references to available taxonomical keys are provided.
• 4 Biological characteristics are extremely diverse among and within the three taxa, resulting in a great variety of strategies in meiobenthic crustaceans. Characteristics of reproduction, sexual dimorphism, cyclomorphosis and population parameters (i.e. clutch size, lifespan, growth, moulting) are provided for some of the most common species.
• 5 Important differences between the three main taxa were found at the species level. Ecological requirements such as hydraulic microhabitats and geomorphologic features of the streambed are the major determinants of species diversity and abundance for benthic microcrustacea of lotic habitats. Many studies on the ecology of these communities are limited by a lack of knowledge of the life history characterisitics of lotic (especially interstitial) crustacean populations.

     

珊瑚藻类对南麂列岛潮间带底栖生物群落多样性的影响

为了解南麂列岛潮间带珊瑚藻类对于其他大型藻类和底栖动物的影响, 在南麂列岛国家级海洋自然保护区布设了4条潮间带断面, 于2012年5月至2013年2月对其生物状况进行了逐季调查, 分别分析了中低潮区大型藻类、非珊瑚藻大型藻类、底栖动物的物种多样性和均匀度, 并计算了大型底栖动物的功能多样性指数Rao's Q。主要结果如下: (1)共采集和鉴定出大型藻类52种, 其中珊瑚藻科藻类有5种; (2)珊瑚藻类在高潮区没有分布, 在中低潮区均占据优势, 占潮间带藻类生物量的68.9%。四季中低潮区大型藻类的Shannon-Wiener多样性指数范围为1.638-4.044, 非珊瑚藻大型藻类的多样性指数范围为1.495-3.809, 底栖动物为5.289-6.917; 大型藻类的Pielou均匀度指数范围为0.819-0.971, 非珊瑚藻大型藻类的均匀度指数范围为0.830-0.973, 底栖动物为0.967-0.988; (3)大型藻类物种多样性和均匀度指数的降低与珊瑚藻类优势度的增加相关, 但珊瑚藻类优势度与底栖动物物种多样性指数、均匀度指数和功能多样性指数均没有显著相关性; (4)底栖动物功能多样性与珊瑚藻类优势度均呈低潮区高于中潮区的变化规律, 但相关性分析表明两者间并无直接联系。推测珊瑚藻类通过竞争占据了其他藻类的生存空间, 从而降低了南麂列岛潮间带大型藻类的物种多样性和均匀度。底栖动物则因其自身生活特点而使得珊瑚藻类的扩张未能影响其多样性水平。     

Southern Ocean deep-sea isopod species richness (Crustacea, Malacostraca): influences of depth, latitude and longitude

We examined deep-sea epibenthic sledge isopod data from the Atlantic sector of the Southern Ocean (SO) (depth range=742–5,191 m). Samples were taken during the expeditions EASIZ II (ANT XV-3) in 1998 and ANDEEP I and II (ANT XIX3/4) in 2002. A total of 471 isopod species were recorded from 28 sites. The species richness of the epibenthic sledge samples was highly variable (6–82 species). Species richness was highest at site 131-3 in 3,053 m depth in the north-eastern Weddell Sea. The highest numbers of species were sampled in the middle depth range and lower species richness was found in the shallower and deeper parts of the study area. Depth is suggested to explain isopod species richness better than both latitude and longitude. Between 58°S and 65°S, the number of species ranged from 9 to 82 (mean=35.9). Further south in the Weddell Sea, between 73°S and 74°S, species richness was lower and the number of species ranged from 6 to 35 (mean=19.2). With regard to longitude, the highest species richness (up to 82 species) was found between 50°W and 60°W in the area of the South Shetland Islands and around the Antarctic Peninsula, while numbers did not exceed 50 species in the eastern Weddell Sea. The haul length, ranging from 807 to 6,464 m, was positively correlated with depth; however, there was no linear relationship between haul length and species richness. We therefore suggest that depth was the most important factor explaining isopod species richness. However, only 28 sites were visited and the statistical power is thus limited. Sampling in the deep sea is expensive and time consuming and as yet this is the best isopod data set available from the Atlantic sector of the SO. Future expeditions are therefore important to better explain the current patterns of benthic diversity in Antarctica.     

An elementary,structural analysis of river phytoplankton

Summary A structural analysis of river phytoplankton has been carried out based upon published studies on 67 rivers. When available on a yearly basis to account for seasonal variability, five structural features have been chosen: species composition, species richness, species dominance, diversity and biomass (total and per taxonomic groups). Despite the high number of reported studies, most of them cover only some of the aforementioned features. As a result of the low amount of studies, tropical rivers are underepresented. No size distribution studies have been carried out on river phytoplankton. The average species richness amounts to 126, being higher in temperate rivers. Roughly one half of each flora is comprised of sporadic species. No statistically significant relationship between species richness and latitude has been found despite the fact that tropical rivers appear to house fewer species than temperate rivers. Also, one half of the support in the floras are either benthic or tychoplanktonic. Diatoms comprise the majority of species numbers in the whole data set but are substituted by desmids in tropical rivers and by green algae when benthic species are not taken into account. There appears to be lower biomass in river phytoplankton than in lakes. Diatoms are also the major taxonomic group comprising total biomass in rivers but they share clearly a lower fraction in tropical rivers. On an average basis, diatoms appear to be more dominant in rivers than in lakes. The time course of diatom dominance occurs close to the summer solstice in tropical rivers whereas is much more lagged in temperate sites. The diversity of river phytoplankton is highly scattered (0.40–4.40 bits ind^–1).     

Biodiversity of peracarid crustaceans(Malacostraca) from the shelf downto the deep Arctic Ocean

During three expeditions with the RVs Meteor and Polarstern more than sixty thousand peracarids were sampled from the deep Arctic Ocean (northern North Atlantic) by means of an epibenthic sledge. Sampling areas were the Kolbeinsey Ridge north of Iceland (800–1100 m), the Northeast Water Polynya, off Greenland (45–517m), and 75°N east of Greenland (197–2681m). Until now 288 species of Peracarida have been identified to species level. These 288 species comprise 152 genera and 59 families of Amphipoda, Cumacea, Isopoda, Mysidacea and Tanaidacea. Thirty-eight genera were very frequent and were sampled at each expedition (these were 22 species of Isopoda, seven species of Cumacea, three species of Amphipoda and Mysidacea, each, and two species of Tanaidacea). Sixty genera are eurybathic, occurring at least over a depth range of 1000m, some even from the shelf up to 2681m depth. Only 10 genera are stenobathic, occurring only in the deep sea. No significant decrease in species number with depth or latitude could be observed. The influencing factors probably causing different community structures are diverse, ranging from food availability over substrate or hydrographical qualities to interspecific competition.     

Diversity and indicator species as measures of water pollution in a subarctic lake

Benthic invertebrates were collected from a subarctic lake during 1976 to assess the effectiveness of diversity indices and indicator species as measures of heavy metal pollution. Collections were made near an operating metal mine, where sediments were contaminated with high levels of arsenic (up to 2,500 mg/kg dry weight), mercury (500 µg/kg), lead (850 mg/kg), copper (750 mg/kg) and zinc (950 mg/kg). A total of 25 species and a diversity index of 2.4—2.9 were recorded in this heavily impacted area. Chironomids (Procladius denticulatus, Heterotrissocladius changi, Chironomus decorus) were most common in the sediments, followed in importance by molluscs (Pisidium casertanum) and oligochaetes (Lumbriculus variegatus). There were 23 and 25 species in the areas of moderate and negligible contamination, respectively. The diversity indices ranged from 2.4–2.6 and 2.4–2.8 and the main species were generally similar to those found in the heavily impacted area. While diversity indices and indicator species were therefore ineffective in monitoring metal contamination, the strong negative correlation between the concentration of metals and the abundance of benthic organisms provided a much more realistic assessment of the level of contamination.     

Taxonomic position of and generic distinction between Parepactophanes Kunz, 1935 and Taurocletodes Kunz, 1975 (Copepoda, Canthocamptidae incertae sedis), with description of a new species from the Black Sea

Both sexes of a new species of Taurocletodes Kunz, 1975 (Copepoda, Harpacticoida, Canthocamptidae incertae sedis ) are described from sandy beaches along the Black Sea coast of Turkey. The genus Taurocletodes is removed from its synonymy with Parepactophanes Kunz, 1935 and re-instated as a valid genus, accommodating the type species T. dubius (Noodt, 1958) comb. nov. and T. tumenae sp. nov. Both genera can be differentiated by major differences in the segmentation of P1–P3 endopods, the absence/presence of penicillate setae on P1 endopod, the number of outer spines on P2–P4 exp-3, the armature of P2–P4 endopods and the sexual dimorphism of P2 endopod and P3 exopod. T. tumenae sp. nov. and T. dubius are morphologically very similar, differing in morphometric characters related to the endopodal segmentation of P1 and P4, and armature of the male P5. The controversial taxonomic status of Parepactophanes and Taurocletodes within the family Canthocamptidae is discussed.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 469−486.     

Benthic fauna in tropical tidal flats of Hinchinbrook Channel, NE Australia: diversity, abundance and their spatial and temporal variation

A survey of the benthic infauna (macro- and mesofauna) in tidalflats of Hinchinbrook Channel, north-east Australia, was carried out toassess the species diversity and individual abundances as well as theirtemporalvariations. Two sites were surveyed at five occassions from November 1988 toOctober 1991. In addition, spatial distributions over the intertidal gradientwere investigated once in May 1990. During the entire survey, over 200 specieswere recorded, with 53 species found on average at each sampling occassion.Species densities ranged from 4.0 to 8.2 species 177cm^–2 for macrofauna and from 4.1 to 11.8 species10 cm^–2 for mesofauna, but varied little betweensites. The average infaunal diversity (H') was 2.53. Individual abundancesreached median values of 14.0 individuals 177cm^–2for macrofauna and 14.5 individuals 10 cm^–2 formesofauna. Changes in total abundances were not related to season andinconsistent at the two study sites, with significantly higher abundancesoccurring either at site A or B on single sampling dates. Transects sampled inMay 1990 showed varying species compositions and abundances in the upper, midand lower intertidal, but no defined benthic communities were revealed bymultivariate analyses. Temporal variations in the benthic assemblages of thetwotidal flats in Hinchinbrook Channel were higher than variations between sites,with a separation of assemblages before and after 1989. Problems to assess andinterpret temporal changes in species rich tropical benthic communities arediscussed.     

A latitudinal gradient in large-scale beta diversity for vascular plants in North America

Species turnover, or beta diversity, has been predicted to decrease with increasing latitude, but few studies have tested this relationship. Here, we examined the beta diversity–latitude relationship for vascular plants at a continental scale, based on complete species lists of native vascular plants for entire states or provinces in North America (north of Mexico). We calculated beta diversity as the slope of the relationship between the natural logarithm of the Jaccard index (ln J ) for families, genera or species, and both geographic distance and climate difference within five latitude zones. We found that beta diversity decreased from south to north; within latitude zones, it decreased from species to genera and families. Geographic and climatic distance explained about the same proportion of the variance in ln J in zones south of c. 50°N. North of this latitude, nearly all the explained variance in ln J was attributable to geographic distance. Therefore, decreasing beta diversity from south to north reflects decreasing climate differentiation within more northerly latitude zones, and primarily post-glacial dispersal limitation north of 50°N.     

Variation in Vertebral Number in Galaxiid Fishes (Teleostei: Galaxiidae): A Legacy of Life History, Latitude and Length

Mean vertebral counts among species of Galaxiidae vary curvilinearly with fish size – large species have more vertebrae (pleomerism). The relationship with size breaks down among adults of diadromous species. There is mostly no relationship between vertebral count and body shape, although an inverse relationship between count and body depth in a series of divergent small galaxiids may reflect a shift in swimming mode. Diadromous populations have more vertebrae than non-diadromous (landlocked) conspecifics (around the same number as related non-diadromous species). Diadromous species have more vertebrae than related non-diadromous species and exhibit rising vertebral number with increasing latitude (Jordan's rule applies). Regressions of vertebral number against latitude differ among conspecific populations from different regions, perhaps reflecting different relationships between latitude and local climate. Differences in counts between diadromous and non-diadromous species are not simply a direct influence of environment on ontogeny, as embryonic development of species/populations undertaking the two distinct life history strategies occurs in similar, freshwater habitats; differences seem likely to be evolved, and to reflect an advantage of higher vertebral counts in marine environments, where diadromous species live as juveniles. This conclusion is supported by correlation between vertebral counts and size of juveniles of diadromous species at return from the sea, suggesting selection for vertebral number during marine life. Overall, vertebral count is thus influenced by a complex amalgam of fish size, life history, and environment. The explanation for pleomerism may well be related to the scaling relationship between length and cross-sectional area (area rises by the square of length increase) leading to increasing stiffness with growth – compensated for in larger species by having more vertebrae. This could also be driven by scaling in the surface area of the articular facets of the vertebrae themselves.     

A new genus and a new species of freshwater Canthocamptidae (Copepoda: Harpacticoida) from wet mosses of Canada

A new genus and a new species of Canthocamptidae: Maraenobiotus canadensis and Neomaraenobiotus laurentiacus (Copepoda: Harpacticoida) are described and their taxonomic relationships are discussed. They have been collected from wet mosses in Northern Canada.     

Support for the Multi-taxa Approach in Biodiversity Assessment, as Shown by Epigaeic Invertebrates in an Afromontane Forest Archipelago

Often a single indicator invertebrate taxon is used for assessing changing landscape patterns. However, we argue here against the exclusive selection of a single group. Covariation in diversity patterns of spiders, carabids, staphylinids and ants were compared in and between five highly naturally-fragmented Afromontane forest patches (size range: 3.5–25.2 ha) in South Africa. Significantly fewer individuals and species were captured in smaller forest patches (<6 ha) for most of the taxa, except Formicidae, where a higher number of species were captured in medium-sized patches (7–9 ha). When sampling effort was standardized, a higher diversity (rarefaction and Simpson's diversity index) was obtained in the smaller patches for Carabidae, Staphylinidae and Formicidae. The only significant positive correlation between taxa, in terms of numbers of species, was between Carabidae and Staphylinidae. The other taxa showed only weak positive correlations between species richness, or negative correlations. Multivariate techniques showed significant species turnover between patch assemblages for each taxon, and also showed that some taxa are more similar in assemblage-structure than others. An index of complementarity showed that species compositions of the selected taxa varied greatly between forest patches of different sizes. Our results support the multi-taxa approach, in conservation studies, even at the level of taxonomically-related groups sharing a common habitat stratum.     

Richness gradients of stream invertebrates across the USA: taxonomy- and trait-based approaches

Large-scale diversity patterns in relationship to environmental factors at multiple spatial scales have been well-studied for many taxonomic groups; however, freshwater ecosystems remain understudied. Biodiversity is now widely recognized to encompass many more factors than just species numbers, particularly the inclusion of functional attributes. In this study, we examined richness patterns of stream invertebrate genera and their biological traits (“functional” richness) across 364 sites in the contiguous USA. In particular, we focused on the relationship between taxonomy- and trait-based richness to test for functional redundancy in stream communities. Further, we obtained environmental data to model the relative importance of local and watershed-scale environmental factors and residual spatial (latitude, longitude) influences on taxonomy- and trait-based richness. Trait richness increased linearly with genus richness (slope ≪ 1), although this appears to be an artifact of the restricted range of genus richness in our study (32 genera maximum). Furthermore, trait richness was significantly lower than expected under random community assembly. In contrast, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) genera exhibited a saturating pattern between trait and genus richness and trait richness was no different from random. Our study indicates that there is functional redundancy among stream invertebrate genera, likely as a result of harsh habitat filters limiting trait diversity. Environmental factors (including spatially structured environmental factors) were always more important than spatial factors (latitude, longitude) in structuring richness despite strong longitudinal patterns of all richness measures (these differences were only significant for EPT genera). Finally, we found no significant difference in the relative importance of local and watershed scale environmental factors for taxonomy- and trait-based richness.     

Assessing the diversity of New Zealand freshwater harpacticoid copepods (Crustacea: Copepoda) using mitochondrial DNA (COI) barcodes

Taxonomic and ecological studies of freshwater harpacticoid copepods are limited globally by the ability to easily and accurately identify specimens. Here, we test the use of the mitochondrial cytochrome c oxidase subunit I (COI) gene locus as a tool for assessing the diversity of freshwater Harpacticoida. We obtained sequences from New Zealand harpacticoid copepods, representing two families, five genera and nine species, including the non-indigenous Elaphoidella sewelli. All species were delineated by the COI gene. However, high intraspecific diversity was evident among populations of Elaphoidella bidens (>12%), and between North and South Island populations of Bryocamptus pygmaeus (>18%), potentially indicating the presence of morphologically cryptic taxa. We suggest that mitochondrial DNA (COI) sequences can provide a useful tool for the routine identification of freshwater harpacticoid copepods. Applications of these data will include assessing species diversity and biogeography as well as assisting with the detection of non-indigenous species.     

Intrusions of the Kuroshio Current in the northern South China Sea affect copepod assemblages of the Luzon Strait

We analyse the influence of the Kuroshio Current on copepod assemblages in the northern South China Sea. The assumption was tested whether predominant current regimes bring marine zooplankton and Copepoda from subtropical and tropical waters to the south of Taiwan. A total of 101 copepod species were identified from 26 families and 48 genera that include Calanoida, Cyclopoida, Harpacticoida and Poecilostomatoida. High copepod abundances in the study area are shown to be caused by both, a year-round Kuroshio Current intrusion and the SW monsoon, prevailing in the South China Sea during summer. Calanus sinicus did not appear in the samples, indicating that there was no cold water mass intrusion in the area during sampling. Both, the intrusion of the Kuroshio Branch Current to the Luzon Strait and the South China Sea circulation may play a more important role in shaping copepod assemblages in the region than hitherto expected. The abundance of copepods was higher above the 50 m isoline than at deeper strata. Species number and the Shannon-Wiener diversity index were higher with increasing depth. Copepod assemblage structure changed with different sampling depth and different sampling areas. Copepod abundance and species richness were higher in the northern South China Sea than in the Kuroshio Current area, and higher at lower latitudes than at higher latitudes. Some indicator species are characteristic for the Kuroshio Current and indicate with others that the study area accomodated water masses from the northern South China Sea as well as from the Kuroshio Current.     

Gelidium pristoides in South Africa

Gelidium pristoides has been harvested commercially from the eastern Cape, South Africa, since 1951, with 40–80 t y^–1 (dry wt) collected in recent years. This species has been intensively studied since 1983, and we briefly review knowledge of its biology in relation to harvesting. We describe a new study of intertidal epiphytic animals, showing that none is specific to G. pristoides, and that only 2.8% of these animals (numbers) inhabit this agarophyte, while the rest are found in other intertidal algal communities: harvesting is considered to have negligible effects on epifauna. Over the past 3 y, we have monitored, at two sites, the effects of the harvesting of G. pristoides on other benthic algae and animals. In only two of the seven main components analysed, did we find any difference between harvested and control plots. At one site only, the number of limpets and percentage cover of Gelidium was higher in harvested plots. These results show that harvesting has no significant biological effect. Regulations governing seaweed exploitation in South Africa were amended in 1988, to encourage local processing of products, and these changes are discussed in relation to the local Gelidium industry. Despite experimental results predicting a higher yield per unit effort if harvesting is limited to summer, harvesting continues throughout the year for practical reasons.