COMMENTS ON THE WATER QUALITY OF THE MHLATHUZE ESTUARY IN RELATION TO DETERMINING THE ECOLOGICAL INTEGRITY CLASS

Summary

Water quality forms an integral component of the determination of the Ecological Reserve of a water resource. This paper presents the available historical and current information on the water quality of the Mhlathuze estuary, The data were assessed in order to determine the forcing factors that characterise the water quality of Mhlathuze estuary. These factors were used in conjunction with a previously-developed water quality indexing system to assign a water quality integrity class to the Mhlathuze estuary. Three reaches of the estuary were classified as being largely natural with few modifications. Major issues relating to water quality data gaps were identified. By addressing these issues an integrity class could in future be assigned with greater confidence.     

A REVIEW OF THE AQUATIC AVIFAUNA OF THE MHLATHUZE ESTUARY

Summary

This paper is the first published review of the aquatic avifauna of the Mhlathuze Estuary. It also uses a regional approach in order to determine the potential for certain hitherto unrecorded species to occur there. The study shows that there appear to have been significant changes in the aquatic avifauna over the past 15 years and that these have, by and large, been negative. However, information on the current status of the avifauna is lacking and it is considered important to determine this as soon as possible.     

A REVIEW OF THE MACROBENTHIC FAUNA OF THE MHLATHUZE ESTUARY: SETTING THE ECOLOGICAL RESERVE

Summary

This paper reviews historical and current ecological information on macrobenthos from the Mhlathuze Estuary before and after development of the Richards Bay Harbour. The fauna is described in terms of the potential influence of a change in freshwater inflow to the system and the requirements for the setting of an Ecological Reserve. Over 95% of the species recorded were primarily marine and to a lesser extent estuarine in origin. Fauna typical of sheltered, soft-bottomed marine environments inhabited the estuary, whereas estuarine fauna was limited to the canalised sections of the Mhlathuze River. Certain areas were characterised by opportunistic species indicative of disturbed or organically enriched sediments while others sustained a high diversity of more sensitive climax species, several of which are endemic to southern Africa. The majority of species belonged to the Class Polychaeta but the estuarine mudcrab Paratylodiplax blephariskios dominated the benthic biomass. The pre-feasibility stage of the Ecological Reserve Determination indicated that a reduction in freshwater input would negatively impact upon the already reduced estuarine component at the head of the estuary. Conversely, if freshwater flow to the estuary is augmented, sediment transport via the river could increase without there being an. improved catchment management policy in place.     

AN OVERVIEW OF THE GENUS PYRRHOPAPPUS (ASTERACEAE: LACTUCEAE) WITH EMPHASIS ON CHLOROPLAST DNA RESTRICTION SITE DATA

The genus Pyrrhopappus in recent systematic treatments has comprised five taxa (four species, one with two varieties), which have now been studied anew using morphogeographical and chloroplast DNA restriction site data. Eight populations, representing all of the recognized taxa of Pyrrhopappus, were digested with 17 restriction enzymes. Only three restriction site differences were found from among 750 restriction sites and no length variations were observed. This contrasts with similar studies, using these same enzymes, on the closely related genus Krigia in which 173 mutation sites and 20 length variations were found among the seven species concerned. Nucleotide sequence divergence values among the species of Pyrrhopappus were extremely low (0.0012) compared to much higher values found in the closely related genus Krigia (0.1270). Three species of Pyrrhopappus are herein recognized: two diploids with 2n = 12 chromosomes, P. carolinianus and P. pauciflorus (including P. multicaulis, P. geiseri and P. rothrockii), and a tetraploid (2n = 24), P. grandiflorus. The tetraploid is partially sympatric with both diploids but is readily recognized by its perennial roots, which bear tuber-like enlargements. These three species presumably arose relatively recently, and the DNA data suggest that neither P. pauciflorus nor P. carolinianus gave rise to the tetraploid P. grandiflorus.     

PRELIMINARY OBSERVATIONS ON THE MACROCRUSTACEA OF COASTAL LAKES IN THE VICINITY OF RICHARDS BAY,ZULULAND, SOUTH AFRICA

SUMMARY

A limited amount of research has been carried out on the four coastal lakes in the Richards Bay area. Due to the impending threat of water pollution from industrial, mining and residential areas within the catchments of these lakes there is an urgent need for the collection of baseline data before it is too late.

This paper reports on preliminary observations on Macrocrustacea of the lakes. A total of 27 species were recorded, of which 8 are new distribution records for the species in fresh water and one, an isopod, is a species new to science from a family previously unrecorded on the African continent. Sixteen of the Macrocrustacea recorded were found to be relict estuarine species.

The relationship between the Macrocrustacea are discussed in terms of habitat and dietary associations. The former category was found to be variable in the shallower Richards Bay lakes as opposed to Lake Sibaya whose depth (40 m) plays an important role in species distribution. Information is provided on habitat, substrata preference, associations with plant communities, and known depth distribution. Dietary data on the Macrocrustacea present in the four coastal lakes showed that seven major feeding groups are present: benthic filter feeders, nektonic filter feeders, periphyton grazers, shredders of dead macrophytes, benthic scavengers, partial carnivores and fish ectoparasites.     

武汉东湖浮游动物对浮游细菌的牧食力研究

利用３５μｍ、６４μｍ、９０μｍ和３６０μｍ等不同大小孔径的筛绢网过滤湖水进行了浮游动物对浮游细菌牧食力的研究。结果表明,东湖浮游动物对浮游细菌总滤过率为１８０．１９ｍｌｌ￣（－１）ｈ￣（－１）．摄食率为０．４０μｇＣｌ￣（－１）ｈ￣（－１）。９０μｍ以下的个体为原生动物和轮虫,它们组成了群落总生物量的７５％,其对细菌的牧食力占总牧食力的４４．８％,大于３６０μｍ的浮游动物（主要是甲壳动物）的牧食力占总牧食力的３５．１％。大于９０到小于３６０μｍ的浮游动物其牧食力最小,只占总牧食力的２０％。文中分别用滤过率、摄食率和特定摄食率对各浮游动物组分进行了比较,甲壳动物的特定摄食率比原生动物和轮虫的特定摄食率之和大。文中并讨论了可能影响浮游动物对浮游细菌牧食力的有关因素。     

巴尔干半岛现生轮藻植物综述

欧洲东南部巴尔干轮藻植物由于其产地生境的差异及以镶嵌状分布的模式,具有较高的生物分异度,计有44种,归属于现生属Nitella(10),Tolypella(4),Nitellopsis(1),Lychnothamnus(1),Lamprothamnium(1) and Chara(27).巴尔干半岛产有4种土著类型Chara rohlenae,Chara ohridana,Chara corfuensis and Chara visianii.建立1新种Chara hydropitys.该地区轮藻植物分布不均衡,部分类型例如Chara strigosa,Chara kokeilii,Chara muscosa,Chara fragifera,Chara imperfecta,Lychnothamnus barbatus为稀有品种,仅在少数地点发现.巴尔干地区轮藻植物之丰富多彩远远超过已知的程度,有待于深入研究.     

武汉东湖后湖区浮游甲壳动物群落结构的研究

武汉东湖后湖湖区浮游甲壳动物群落结构从60年代至90年代发生了十分显的变化。浮游甲壳动物的物种丰度下降非常明显,枝角类的种类数从60年代的47种下降至90年代的17种,桡足类的种类数由60年代的14种下降为90年代的9种。60年代枝角类的优势种隆线Sou一亚种在90年代被短尾秀体Sou所取代,60年代的两种优势哲水蚤－长江新镖水蚤与特异荡镖水蚤的优势在90年代消失,而60年代很少的一种剑水蚤－台湾温剑水蚤在90年代跃升为优势种。随着滤食性鱼类密度的上升,枝角类的密度从60年代至90年代显下降。哲水蚤1997及1998年的密度明显低于60年代的密度。研究表明,浮游甲壳动物群落物种丰度的下降与后湖湖区沉水植被的退化有关,而优势种的演替主要受滤食性鱼类密度的影响。     

ASPECTS OF COMPARATIVE PLANKTON ECOLOGY IN CASCADING MGENI RIVER RESERVOIRS (MIDMAR,ALBERT FALLS,AND NAGLE): AN OVERVIEW

Summary

An overview of a three year study of abundance, community structure and succession of zooplankton and phytoplankton in relation to physical limnological conditions in Lakes Midmar and Albert Falls is presented, along with findings on zooplankton from a nine month study of Lake Nagle. Physical stability increased between Midmar (mean summer N² = 6.55 × 10⁴ s²) and Albert Falls (N² = 8.70 × 10⁴ s²), in line with elevations in water temperature. Phytoplankton richness and diversity was similar in these reservoirs, although zooplankton species richness increased downstream. Abundance levels of both phyto- and zoo-plankton were broadly comparable in these two reservoirs. In Midmar and Albert Falls, overall mean (± SD) chlorophyll levels were 3.60 ± 1.54 and 3.41 ± 1.41 μg 1¹, with corresponding overall average zooplankton standing stocks of 0.85 and 0.76 g m² dry mass, dropping to 0.54 g m² in Nagle (for which spring to midsummer data are missing).

Ruderal and colonist phytoplankters were persistently dominant both in Midmar and Albert Falls, in keeping with the continuous (if incomplete) mixing patterns evident in these reservoirs. Few stress tolerant algae occurred. The summer ruderal assemblage was unexpectedly dominated by diatoms in the physically more stable conditions of Albert Falls, but not Midmar. Mean zooplankton grazer-induced instantaneous mortality rates for planktonic algae for the whole study were estimated (by regression predictions) as 0.17 d¹ in both lakes. Phytoplankton was not studied in Nagle.

Changes in zooplankton community structure between Midmar and Nagle largely involved progressive increases in the contribution of smaller-bodied cladocerans (comprising both sequentially smaller species of Daphnia (D. pulex, D. longispina, D. laevis), and additional genera such as Diaphanosoma, Ceriodapnia, Moina and Bosmina). As with a parallel progressive switch between Metadiaptomus meridianus and Tropodiaptomus spectabilis over this series of reservoirs, (and the temporal separation of “co-existing” populations in Albert Falls), which has been shown experimentally to be strongly temperature-linked, changes in absolute temperature are implicated as a primary causal factor in the shifts in cladoceran species composition. Temporal occurrences of these species also indicate the primacy of temperature.     

火赤链游蛇卵孵化的进一步研究兼评孵化水环境的影响

用 2× 2四种温、湿度孵化火赤链游蛇 (Dinodonrufozonatum)卵 ,重点评估湿度及其与温度的相互作用对孵化成功率、胚胎利用卵内物质和能量及孵出幼体特征的影响。卵在孵化过程中净吸水导致重量增加 ,孵化温、湿度及其相互作用显著影响孵化卵的重量变化并导致卵内水环境的相应变化。同一湿度下 ,低温孵化卵的终末重量大于高温孵化卵 ;同一温度下 ,高湿度孵化卵的终末重量大于低湿度孵化卵。温度显著影响孵化期 ,湿度及其与温度的相互作用对孵化期无显著的影响。孵化温、湿度对孵化成功率和孵出幼体性别无显著的影响。2 4℃和 30℃中均有畸形幼体孵出 ,但畸形率与孵化温、湿度无关。孵化基质湿度显著影响孵出幼体的大小(snout ventlength ,SVL)、湿重和躯干干重 ,潮湿基质中孵出幼体的SVL和体重较大且躯干发育较好。孵化温度显著影响幼体剩余卵黄的干重和灰分含量以及幼体的能量和总灰分含量 ,30℃孵出幼体的剩余卵黄较大、总灰分含量和剩余卵黄灰分含量较高 ,但能量较低。在所有被检测的幼体特征中 ,孵化温、湿度相互作用仅影响剩余卵黄干重。各条件下孵出幼体的最大持续运动距离与其SVL无显著的相关性 ,孵化温、湿度及其相互作用对孵出幼体最大持续运动距离无显著的影响。孵化水环境虽然影响部分幼体特     

PATTERNS OF DISTRIBUTION OF DIATOM ASSEMBLAGES ALONG ENVIRONMENTAL GRADIENTS IN THE SEVERN RIVER ESTUARY,CHESAPEAKE BAY,MARYLAND1

Distribution patterns of diatoms from natural substrates and surface waters of the Severn River, Maryland, are related to salinity and seasonal gradients through time and spare by minimum spanning tree cluster analysis and principal components analysis. Assemblages were found to be distributed in a complex but orderly fashion, with primary discontinuities occurring between seasons, and between planktonic and attached forms. Within seasons, benthic groupings are distributed as continua along a horizontal salinity gradient, with one discontinuity at a location with a mean salinity of approximately 7‰, Downstream from this discontinuity, most species do not follow the changing salinity patterns from season to season, and are considered euryhaline for a salinity range of 8–16‰. Upstream from this discontinuity there is a relatively distinct and persistent assemblage of oligohaline indicators. Evidence derived by comparing this study with similar studies from Oregon estuaries indicates that similar distribution patterns, community structures and taxa can be expected to occur in estuaries on the east and west coasts of North America.     

PATTERNS OF DISTRIBUTION OF DIATOM ASSEMBLAGES ALONG ENVIRONMENTAL GRADIENTS IN THE SEVERN RIVER ESTUARY,CHESAPEAKE BAY,MARYLAND1

Distribution patterns of diatoms from natural substrates and surface waters of the Severn River, Maryland, are related to salinity and seasonal gradients through time and space by minimum spanning tree cluster analysis and principal components analysis. Assemblages were found to be distributed in a complex but orderly fashion, with primary discontinuties occurring between seasons, and between planktonic and attached forms. Within seasons, benthic groupings are distributed as continua along a horizontal salinity gradient, with one discontinuity at a location with a mean salinity of approximately 7%o. Downstream from this discontinuity, most species do not follow the changing salinity patterns from season to season, and are considered euryhaline for a salinity range of 8–16%o. Upstream from this discontinuity there is a relatively distinct and persistent assemblage of oligohaline indicators. Evidence derived by comparing this study with similar studies from Oregon estuaries indicates that similar distribution patterns, community structures and taxa can be expected to occur in estuaries on the east and west coasts of North America.     

孵化温度对火赤链游蛇幼体特征的影响兼评剩余卵黄的功能

研究３ 个温度中孵出火赤链游蛇（ Ｄｉｎｏｄｏｎ ｒｕｆｏｚｏｎａｔｕｍ） 幼体的特征并评估剩余卵黄的功能。孵化温度显著影响孵化期和孵出幼体的体长和尾长。与其他类似研究结果不同的是, 低温（２４℃） 孵出的幼体体长和尾长小于较高温度（２８ ℃和３０ ℃） 孵出的幼体。在２４ ～３０℃温度范围内, 孵化温度对孵化成功率、胚胎对卵内物质和能量的利用、幼体的性比和畸形率、孵出幼体总干重及躯干长、剩余卵黄和脂肪体干重无显著影响。孵出的雄性幼体数量显著多于雌性幼体。剩余卵黄的主要功能是用于孵出幼体的早期维持和躯干的生长。新生卵内容物中８１－４ ％ 的干物质、７０－０％ 的脂肪和７９－４ ％ 的能量在孵化过程中被转移到幼体。     

THE PHYLOGENETIC RELATIONSHIPS OF THE PHAEOTHAMNIOPHYCEAE, WITH COMMENTS ON CERTAIN CAPSOID MEMBERS OF THE CHRYSOPHYCEAE

The algal communities of the Flower Garden Banks National Marine Sanctuary have not been comprehensively evaluated and only a few dominant macroalgal species have been reported. This study utilizes both destructive and non-destructive sampling techniques to characterize and taxonomically identify the 'algal mat' community structure. The East and West Flower Garden Banks are located on the outer continental shelf approximately 200 km off the Texas-Louisiana coastline. The average depth of both banks is 100 m with the crest approximately 20 m from the surface. Harvest and photogrammetric samples were collected during two extended cruises to the Flower Garden Banks in October 1998 and March 1999. Forty, 0.25-m² quadrats of standing stock material were randomly collected along with one hundred sixty-one 0.25 m² photo-quadrats from an average depth of 27 m. Photo-transparencies were projected to an actual size grid with 25 random points. Four thousand twenty-five transparency points were evaluated and used to calculate percent composition of algal cover. Harvest samples were used to characterize the "algal mat" composition, species richness, abundance, and biomass. Forty-two species were identified from the samples representing 14 Orders. The "red algal mat" was the dominant algal coverage comprising 38.4% of all photogrammetric samples. This mat was primarily composed of members from the Order Ceramiales. Centroceras, Ceramium , and Polysiphonia comprised 33.4% of the mat, Anotrichium and Hypoglossum , 22.4%.     

THE FIRST FOSSIL PROSCOPIIDAE (INSECTA, ORTHOPTERA, EUMASTACOIDEA) WITH COMMENTS ON THE HISTORICAL BIOGEOGRAPHY AND EVOLUTION OF THE FAMILY

Abstract:  Eoproscopia martilli gen. et sp. nov. is described from the Early Cretaceous (Aptian) Crato Formation Lagerstätte of Ceará State, north-east Brazil. The new taxon is assigned to the extant family Proscopiidae and represents the first occurrence of the group in the fossil record. Eoproscopia is similar to crown group proscopiids in its stick-like habitus, elongate prothorax and absence of the cryptopleuron, but differs in the presence of well-developed wings, the short head with a small, simple fastigium, the prothoracic legs being inserted near the posterior margin of the prothorax, and the absence of spines on the metathoracic tibiae. The discovery of Eoproscopia extends the geological range of the family by approximately 110 myr and confirms the presence of stem-group proscopiids in the Atlantic rift zone of South America during the Early Cretaceous.     

甘草酸,甘草次酸的提取分离及应用概况

本文简要介绍了甘草酸和甘草次酸的提取精制技术、含量测定方法及其主要用途。