Vertical distribution of epipelagic siphonophores at the confluence between Benguela waters and the Angola Current over 48 hours

The diel distribution of epipelagic siphonophores at a station off northern Namibia (18°00 S 10°30 E) was studied. This area is characterized by the mixing of surface waters of the Angola Current with the waters of the northernmost Benguela region. During the sampling period, the continuous flow of the Angola Current gave rise to a marked thermocline at ca 30 m depth. In order to study the diel vertical distribution patterns of epipelagic species under these hydrographic conditions, narrow depth horizons in the top 200 m of the water column were sampled repeatedly over a 48 h period. Thirty-four species were collected. Sphaeronectes gracilis and Chelophyes appendiculata predominated. Increasing numbers of species and individuals were observed on the second day of sampling, particularly in the layers above the thermocline. Only a few species showed an upward nocturnal migration that crossed the boundary between 2 water masses. The differences in the depth distributions of the various species were related to 3 distinct phenomena: the existence of 2 separate siphonophore populations associated with each of the 2 water masses; vertical migration by the most abundant species, which were able to cross the thermocline; and differences in patch size for the most epipelagic species.     

Diatoms in recent Atlantic (20° S to 70° N latitude) sediments: abundance patterns and what they mean

Valve abundances of marine planktonic, marine benthic and freshwater diatoms in 780 sediment surface samples from the North and Equatorial Atlantic between 20° S 75° W and 70° N 10° E display patterns that do not correspond to published records of primary production in the photic zone. On the contrary, their abundance is more closely related to dissolution and dilution by terrigenous minerogenic and biogenic carbonate material. Highest abundances of marine planktonic diatoms occur in the northern North Atlantic south of Iceland and in the equatorial regions. The central North Atlantic and the central Caribbean, which feature lower primary production in the photic zone, contain few or no diatoms in surface sediments. African derived freshwater diatoms are concentrated in a lobe between 5° S and 20° N latitude decreasing in numbers from the African continent westward.Lars Gronlien died unexpectedly in January 1992.     

Vertical and seasonal distribution of flying beetles in a suburban temperate deciduous forest collected by water pan trap

Vertical and seasonal distributions of flying beetles were investigated in asuburban temperate deciduous forest in Kanazawa, Japan using water pan traps to determine the abundance and composition among vertical strata, change in the abundance and composition through seasons and determinant factors in generating the distributions. Traps were placed at three levels (0.5 m, 10 m, and 20 m above ground) on a tower. Samplings were carried out seasonally from May to November in 1999 and 2000. Variations in the abundance of flying beetles were observed from different layers. The results showed that the abundance and composition of flying beetles varied among strata and seasons. In both 1999 and 2000,Elateridae was consistently most abundant in the bottom layer, while Attelabidae and Cantharidae were most abundant in the upper layer. In 1999, Eucnemidae and overall scavengers were most abundance in the bottom layer, but results were not consistent with those in 2000. In general, the abundance of herbivores reaches a peak in the early season(May/June) and decreases in the following months. Peaks of abundance in predators vary vertically. In the bottom layer a peak was observed in the early season (May/June), while in the upper layer this was observed in July. Scavengers had two peaks, in May/June and September. These patterns indicated that vertical distributions in the abundance of differentfeeding guilds varied through seasons.     

Distribution and seasonal dynamics of <Emphasis Type="Italic">Boroecia maxima</Emphasis> (Ostracoda: Halocypridinae) in the Arctic basin and adjacent Atlantic waters

Based on materials obtained during Soviet and Russian expeditions to the Arctic basin and adjacent Atlantic waters during the period from 1929–1993, as well as data from the literature, we examined the distribution range of the common deep-sea ostracod Boroecia maxima. This species occurs throughout the pelagic water column (down to 3000 m depth and below) and prefers low water temperatures (surface Arctic and intermediate water masses). During the year, at all depths, the ratio between age groups of B. maxima remains virtually unchanged. Breeding apparently continues year-round. During the polar night, B. maxima makes no migration into warm Atlantic water, where wintering predatory zooplankton occur in large numbers, and thus avoids grazing pressure.     

Vertical distribution and abundance of benthic invertebrates in profundal sediments of Mondsee,with special reference to oligochaetes

Two profundal sediment sites at the same depth (MO₁ and MO₇) in Lake Mondsee differed considerably in their trophic conditions. Based on organic carbon (weight loss on ignition) and redox values, MO₁ sediments could be classified as eutrophic, MO₇ sediment as oligo- to mesotrophic. Investigations on abundance, diversity and vertical distribution of meio- and macrofauna exhibited distinct differences between the two sampling sites. MO₇ showed a much higher diversity than MO₁. Seven species of ostracods and oligochaetes respectively, were found at MO₇, but only two species of oligocheates at MO₁. The vertical distribution of meiofauna at MO₇ corresponded to redox values. Chironomids were found in the uppermost 4 cm of sediments. Oligochaetes penetrated 15 to 20 cm into the sediment. Nearly 100% of the adult oligochaetes and cocoons occurred only below the first three centimeters of sediment. Their distribution patterns are discussed.     

Distribution of <Emphasis Type="Italic">Boroecia borealis</Emphasis> (Ostracoda: Halocyprididae) in the Arctic Ocean and adjacent waters of the Atlantic

The geographical and vertical distribution of Boroecia borealis was studied based on literature data and materials collected by Soviet and Russian expeditions in the Arctic Ocean and adjacent waters of the Atlantic during the period from 1929 to 1993. In the region of study, this species occurs at a temperature from 0.5 to 17.7°C. In the Arctic basin, B. borealis is predominantly found in the warm deep Atlantic layer. The central Arctic region is not a zone of exclusion of this species, but is a part of the species’ range, where its apparently dependent populations occur. In the northern Atlantic, B. borealis can reach into the low latitudes as far as 30°N.     

Climate-driven changes in abundance and distribution of larvae of oceanic fishes in the southern California region

We examined climatic effects on the geographic distribution and abundance of 34 dominant oceanic fishes in the southern California region using larval fish data collected from the 50‐year long California Cooperative Oceanic Fisheries Investigations (CalCOFI) surveys. The oceanic species responses to environmental changes in their geographic distributions were not very pronounced, perhaps because they lived in the deep layer where temperature change was relatively small or because the environmental variation of the CalCOFI region is not strong enough (with an average temperature gradient of the upper 100 m around 91 km °C^?1). Among the 34 taxa, 16 showed a significant distributional shift (median latitude or boundaries) in relation to environmental variables, and eight species significantly shifted their geographic distribution from the 1951–1976 cold period to the 1977–1998 warm period. Interestingly, the vertically migrating taxa more often showed a significant response to environmental variables than the nonmigrating mesopelagic taxa, reflecting the more significant increase in heat content of the upper ocean (<200 m), compared with the deeper zone (300–500 m) where the mesopelagic fishes typically remain. Climate change has significant effects on the abundances of oceanic fishes. Twenty‐four taxa exhibited a significant change in abundance in relation to environmental variables, and 25 taxa, including both warm and cold‐water taxa, showed a significant increase in abundance from the cold to warm period. Analysis of physical data indicated that the surface‐layer (20–200 m) warmed significantly and the isotherms approached shoreward from the cold to the warm period. We further show that the spatial distribution of coastal–neritic fish retreated shoreward and oceanic fish extended shoreward from the cold to warm period. Our results suggest intensified stratification of the southern California region during the warm period may create a suitable habitat for the oceanic species. Moreover, such an unfavorable condition (e.g. changes in food habitat) for coastal–neritic species might result in competitive release for the oceanic fishes to flourish.     

福建中部近海浮游动物数量分布与水团变化的关系

根据2009—2010年在福建中部近海24°55'—25°13'N、119°11'—119°32'E水域冬、春、夏3个季节的调查资料,探讨了该水域浮游动物总丰度与生物量的平面分布、季节变化及其与台湾海峡水团变化的关系。结果表明,调查水域浮游动物的数量在冬、春之交变化较大,而在春、夏季变化较小。浮游动物冬、春两季的平均丰度分别为8.90 个/m³和245.65 个/m³,夏季为236.82 个/m³。冬、春两季,该水域浮游动物的分布特征相近。其数量在近岸较高,向外侧水域逐渐降低。冬季浮游动物的丰度最高为31.56 个/m³,春季最高达到831.67 个/m³。中华哲水蚤(Calanus sinicus)是冬、春季影响总丰度变化最主要的种类。与冬、春季不同,夏季浮游动物的数量在离岸水域较高,丰度最高达1053.13 个/m³,而在近岸较低,最低值仅19.17 个/m³。汉森莹虾(Lucifer hanseni)、双生水母(Diphyes chamissonis)是影响总丰度变化最主要的种类。浮游动物在各季的不同分布特征与台湾海峡的季节性水团变化有关。受季风转换影响,从冬季到夏季,海峡内沿岸流势力逐渐减弱,台湾暖流水势力逐渐增强,并影响到沿岸的水文环境。这导致调查水域内浮游动物的优势种类由暖温种向暖水种演替。由于冬、春季的重要优势种类中华哲水蚤与夏季的汉森莹虾、双生水母具有不同的温度适应性,受不同性质水团的影响,在近岸和离岸水域各自呈现出不同的数量高低。从而进一步影响到各季浮游动物总数量的分布。     

The distribution of Gobius cobitis in the British Isles

Records of occuerence of Gobius cobitis on the British coast are listed from the literature and from extensive collecting in interfidal areas. In Britain the number of suitable habitats is reduced and the density of population is lower than in the Channel Islands and Brittany.     

Vertical distribution of Atlantic salmon (Salmo salar) as a function of illumination

The vertical distribution of cultured Atlantic salmon larger than 1 kg was monitored by hydroacoustics in both a shallow (6 m) and a deep (20 m) cage. Surface light levels and fish distribution were registered for three periods throughout the year. The two fish groups were fed calculated rations twice a day. During the winter and spring (including vernal equinox), the fish were distributed at around 5 m depth in both cages when not feeding. Around summer solstice, the fish preferred deeper waters when not feeding. The light dependency of the vertical migration was pronounced, and indicates clearly that even a 20 m deep cage is not deep enough to meet the depth requirements of large Atlantic salmon during summer.     

Review of the taxonomy of the Calanidae (Copepoda) and the limits to the genus Calanus

Conflicting systems of classifying the Calanidae (Brodsky, 1972; Bradford & Jillett, 1974) are analysed and a preferred system recommended. Brodsky's system, based on characters with assumed adaptive and functional significance is rejected as is his claim to have produced a phylogenetic scheme. Bradford & Jillett's system, based on a variety of characters, results in a coherent classification which aims to be neutral concerning phylogenetic relationships among genera. Species of Calanoides, Calanus, Nannocalanus, and Neocalanus are surveyed and the need for further taxonomic work is assessed.     

大亚湾大辣甲水域溶解无机碳垂直分布特征及季节动态

于2007年10月～2008年9月进行了4个季节的垂直采样监测,对大亚湾大辣甲水域溶解无机碳(DIC)的垂向分布和季节动态特征进行了研究,分析了大亚湾溶解无机碳与各环境要素(pH、水温、溶解氧和叶绿素a等)的相关性。结果表明:在春、秋和冬季,大亚湾大辣甲水域DIC含量在垂直分布上差异较小,但夏季(2008年7月)变化较为显著,DIC含量的变化范围为16.79～26.52mg·L^-1;DIC高值基本集中在中、底层水域(8～16m),尤以底层水域(13～16m)为甚;DIC含量基本呈现出春、夏季较高,秋、冬季较低的分布趋势;DIC含量与pH值和水温含量显示出了负相关关系,而与盐度呈正相关关系。     

How species richness and total abundance constrain the distribution of abundance

The species abundance distribution (SAD) is one of the most intensively studied distributions in ecology and its hollow‐curve shape is one of ecology's most general patterns. We examine the SAD in the context of all possible forms having the same richness (S) and total abundance (N), i.e. the feasible set. We find that feasible sets are dominated by similarly shaped hollow curves, most of which are highly correlated with empirical SADs (most R² values > 75%), revealing a strong influence of N and S on the form of the SAD and an a priori explanation for the ubiquitous hollow curve. Empirical SADs are often more hollow and less variable than the majority of the feasible set, revealing exceptional unevenness and relatively low natural variability among ecological communities. We discuss the importance of the feasible set in understanding how general constraints determine observable variation and influence the forms of predicted and empirical patterns.     

The occurrence of Calanidae species in waters off Argentina

As food of planktivorous fish and likely good predictors of natural perturbations, members of the family Calanidae are recognised to be key species in ecosystems worldwide. The distribution and seasonal relative abundance of the Calanidae species occurring in the Argentine Sea were reviewed from published and unpublished data collected over the last three decades. Species are also figured in order to elucidate any possible taxonomic uncertainty. Calanoides cf. carinatus, Calanus australis and Calanus simillimus are the most abundant calanids in the region. The former two species typically inhabit inner and middle shelf waters decreasing offshore, while Calanus simillimus is distributed in the middle and outer shelf, its abundance increasing towards the shelf-break. The southern limit of the distribution of Calanoides cf. carinatus appears to be 46° S. Calanus australis is the most common large copepod in coastal and inner shelf waters off southern Patagonia. Neocalanus tonsus and Calanoides patagoniensis are a much rarer species. The latter is recorded in the southwestern Atlantic, for the first time, immediately east of Magallanes Strait and the Beagle Channel. The taxonomic status and worldwide biogeographic distribution of the region's calanids are briefly described and the patterns identified off Argentina are discussed in relation to the major hydrographic characteristics.     

The effects of host-plant distribution and local abundance on the species richness of agromyzid flies attacking British umbellifers

Abstract. 1. The number of agromyzid species (Diptera: Agromyzidae) attacking British Umbelliferae generally increases with the size of the geographic range of the host, measured as occupied 10 km squares in the Atlas of the British Flora (Lawton & Price, 1979). 2. In the present study we tried to explain the large, residual variation in this species—area relationship using two new variables, namely the local abundance of the host plant, and the number of habitats within which it grows. 3. Local abundance was estimated from eight floras that map plant distributions within English countries by tetrads (2 times 2 km squares). Local abundance was defined as: Total number of occupied tetrads Total number of available tetrads within occupied 10 km squares 4. The number of habitats occupied by each host plant was taken from the only county flora to record plant habitats objectively, that for Warwickshire. 5. We expected to find a correlation between local abundance and the residuals from the national species—area relationship, with locally scarce plants having fewer agromyzids than expected from the sizes of their national ranges, and vice versa. 6. What we found was that size of geographic range and local abundance were highly correlated; hence their relative contributions to agromyzid species richness were difficult to disentangle. Residuals from the national species—area relationship were positively correlated with local abundance, but the relationship marginally failed to achieve statistical significance (P= 0.06). 7. In contrast, the number of habitats occupied by each species of umbellifer in Warwickshire had a marked effect upon agrornyzid species richness, with plants that grow in more habitats supporting more species of insects. Not surprisingly, local abundance and number of habitats occupied were highly correlated. 8. Lawton & Price's observation that aquatic umbellifers are faunally impoverished now emerges as part of the general effect of number of habitats occupied by the host plants on agromyzid species richness. 9. Once the number of habitats occupied by each host plant in Warwickshire was entered into a multiple regression, the effect of size of host geographic range on agromyzid species richness was no longer statistically significant. 10. A combination of the number of habitats occupied, and leaf-form of the host (the latter taken from Lawton & Price, 1979), explains 61% of the variation in agromyzid species richness on British Umbelliferae.     

Distribution and seasonal abundance of benthic macroinvertebrates in a subtropical Florida lake

We studied the distribution and seasonal abundance of benthic macroinvertebrates from July 1975 through September 1976 in a hypereutrophic lake in subtropical Florida. The benthic community was comprised principally of oligochaetes (56.1%), chironomids (37.1%), and chaoborids (5.7%). Numbers of taxa and mean densities correlated negatively with depth and positively with mean grain size of the substratum and dissolved oxygen concentration at the mud-water interface. Seasonal abundances and life history information obtained for the predominant species of Chironomidae (Polypedilum halterale, Glyptotendipes paripes, Chironomus crassicaudatus, Cryptochironomus fulvus, C. blarina, Cladotanytarsus sp., Procladius culiciformis, and Coelotanypus concinnus) indicated that all of these species are multivoltine with rapid generation times. Larval lengths of life at summer temperatures, 27–31 °C, ranged from 14–22 days indicating that sampling in subtropical lakes should be at short intervals (approximately 3 days) if the life cycles, ecology, and function of the components of the benthic community is to be understood.     

Distribution and abundance of young fish in the St. Clair River and associated waters,Ontario

Fish larvae were sampled in 1986 in the St. Clair River, and adjacent waters. Species richness (9 taxa as larvae; 4 others as juveniles) and abundance was lowest in the river, where many larvae (e.g., burbot, rainbow smelt, and yellow perch) were in transit from Lake Huron. The most abundant, and localized, species was gizzard shad, which reached a peak mean density of 4600 larvae 100 m^-3 in an agricultural canal. Adjacent waters contribute greatly to the fish communities of the river and adjoining Lakes Huron and Erie, especially in terms of the number and quantity of forage species.     

土壤剖面碳氮稳定同位素自然丰度的垂直分布模式及其影响机制

土壤碳、氮稳定同位素自然丰度(δ13C和δ15N)随土壤深度变化的研究,对揭示碳、氮元素生物地球化学循环机制具有重要意义.本文在概述土壤剖面δ13C和δ15N垂直分布特征的基础上,重点介绍了土壤δ13C和δ15N垂直分布模式的影响机制.土壤剖面δ13C垂直分布模式的影响机制主要有3种:1)植被δ13C值的历史变化;2)...     

Shingle habitats in the British Isles

RANDALL, R. E., 1989. Shingle habitats in the British Isles . Shingle is the term applied to sediments larger in diameter than sand but smaller than boulders. Around Great Britain there are almost 900 km of pure shingle and vast stretches of rock/shingle, sand/shingle and mud/shingle mixtures. Outside Japan, New Zealand and north-west Europe, shingle is an uncommon coastal sediment. Shingle may form fringing beaches, spits, bars, cuspate forelands and offshore barrier islands, depending upon available supply of sedimentary material and coastal topography.
Species composition on shingle features is partly determined by climate which affects the geographic range of certain species. The other major factors are beach stability and beach composition. Climate results in distinctive patterns in the flora but within the each climate zone beach movement will affect the quantity of annuals, short-lived or long-lived perennials present. The presence or absence and nature of the fine material within the shingle will cause different combinations of species ecologically related to those of sand dunes, salt-marsh or cliff. Coastal shingle vegetation has a distinctive flora which contains several rare or declining species as well as some common coastal and ruderal plants.
At the largest shingle sites a successional sequence can be recorded which initiates with halophytic forbs near the foreshore and moves through neutral to acid grassland species with shrubs and prostrate scrub in the more inland areas.     

Vertical distribution and seasonal variation of eelgrass beds in Iwachi Bay,Izu Peninsula,Japan

The vertical distribution and population structure of eelgrass beds were surveyed in Iwachi Bay, along the Pacific coast of central Japan. Samplings were conducted from May through November 1977 by SCUBA. Eelgrass was distributed between 3 and 11 m in depth. The relative light intensity at 12 m depth was 11% at the lower range. The highest population density was 290 shoots/m² in September and the fresh weight of biomass was 888 g/m² in July at 7 m depth. The maximum mean leaf area index was about 3 at 10 m depth in July. The ratio of reproductive shoots to the total shoots was about 36% at 7 m depth in June. Eelgrass showed good growth at 7–10 m depth, which is comparatively deeper than other eelgrass habitations. The high values of water transparency and sunshine duration, as well as solar radiation compared with other localities was believed to contribute to the growth of eelgrass in deeper waters in Iwachi Bay.