Hydrobiologia

Moubayed, Z.

doi: 10.1007/BF00010807pmid: N/A

Abstract The author describes the male imago and pupa of Chaetocladius algericus sp.n. from Algeria and the male imago of Smittia durandae sp.n. from Lebanon.

Bērzinš, Bruno;Bertilsson, Jan

doi: 10.1007/BF00010808pmid: N/A

Abstract A large material of planktic and semiplanktic microcrustaceans from different types of waters in south and central Sweden was computerized. The more frequent species were ranked according to phosphorus content (tot-P), electrolytic conductivity and content of suspended matter, searching for correlations with the trophic degree. With few exceptions, species indicating oligotrophy are found at lower factor values and those indicating eutrophy at higher values concerning all the abiotic factors considered.

Huys, Rony;Thistle, David

doi: 10.1007/BF00010809pmid: N/A

Abstract Bathycamptus eckmani gen. et spec. nov., which is associated with mudballs produced by the. cirratulid Tharyx luticastellus, is described from bathyal muds in San Diego Trough, off California. ?Heteropsyllus minutus Wells from the Haden Ground, Scotland is considered to be its closest relative and is placed in the same genus. The genera Bathycamptus and Psammocamptus Mielke are regarded as sister groups on the basis of the shared sexual dimorphism shown by P3-P4. Relationships with other marine Canthocamptidae are discussed, and a re-evaluation of the genus Hemimesochra Sars is made. It is concluded that this genus should encompass only the type species H. clavularis Sars. ?Leimia dubia Wells and H. nympha Por are transferred to the new genus Boreolimella, which is closely related to Bathycamptus but not to Leimia Willey. The genus Perucamptus gen. nov. is established to include H. rapiens Becker and shows no clear relationship with the other genera. H. trisetosa Coull is assigned to Caroliiaicola gen. nov., which is regarded as being an advanced member of the Paranannopidae. H. secunda Wells is recognised as belonging to Mesopsyllus Por; whilst H. nixe Por is considered the type species of a new genus Pusillargillus.

Soetaert, Karline

doi: 10.1007/BF00010810pmid: N/A

Brendock, Luc;Alit, Osman M.;Claeys, Dirk;Moghraby, Asim El;Dumont, Henri J.

doi: 10.1007/BF00010811pmid: N/A

Abstract A lightweight LRF 104 laser rangefinder was used in lake mapping. As an example, the Malha crater (Darfur, West-Sudan), containing a lake, springs, wells, and vegetation, was mapped.

McCahon, C. P.;Whiles, A. J.;Pascoe, D.

doi: 10.1007/BF00010812pmid: N/A

Abstract The acute toxicity of cadmium to three larval instars (1 st, 3rd and 4th) of the cased trichopteran Agapetus fuscipes Curtis was determined for animals both in the cased and uncased state. First instar larvae were significantly more sensitive than 3rd or 4th instars and for all ages cased animals were more resistant than uncased. Sub-lethal toxicity was demonstrated by a reduction in case building activity and aggregation response. The need to consider life cycle information when designing toxicity testy and the importance of incorporating sub-lethal responses into a study are discussed.

Weatherley, N. S.;Ormerod, S. J.

doi: 10.1007/BF00010813pmid: N/A

Abstract Models are developed which predict changes in macrofloral and macroinvertebrate assemblages in response to surface water acidification. Empirical relationships between assemblage type and water chemistry are used to predict the probabilities of species occurrences during acidification, as recreated by the hydrochemical model, MAGIC. The water chemistry of two streams is simulated between 1844 and 2124. From 1958, alternative scenarios involved either moorland or conifer forest. From 1984, sulphate deposition was either constant or reduced by 50%. Alternative ecological models driven by pH or total hardness are compared. The floral model showed minor differences between scenarios, probabilities of species occurrence changing gradually and reaching stable values by around 1964. For certain invertebrate species the occurrence probabilities changed rapidly over relatively short periods, for example in the late 20 h century under moorland with constant deposition. Reduced sulphate deposition prevented decrease of acid sensitive species in moorland scenarios but not under forest, which greatly accelerated faunal changes irrespective of deposition pattern. Differences between the pH and hardness models indicated that the effects of these parameters should be separated in future studies. Where an earlier model showed only step changes in invertebrate assemblage type, this new approach can model more precise taxonomic shifts occurring with acidification. Such changes could be important to conservation, or as early indicators of response to pollution. The tentative simulations here suggest that large taxonomic changes may occur over relatively short periods during acidification.