Kay Van Damme

Crustacean species richness in temporary pools: relationships with habitat traits

We examined species richness separately for cladocerans and ostracods in 52 temporary pools in a small geographical area, relating species richness with habitat traits using multiple regressions. Habitat traits considered included surface area, water depth, permanence and sediment depth. Permanence was an important predictor of species richness of both cladocerans and ostracods. Additionally, variation in ostracod species richness was significantly explained by water depth (negative relationship) and sediment depth (positive relationship). Surface area was not a statistically significant factor in any of our analyses. The importance of permanence supports the hypothesis that extinction due to pool drying is a major driving force behind the structuring of microcrustacean communities in temporary pools.

Physical and chemical limnology of alpine lakes and pools in the Rwenzori Mountains (Uganda–DR Congo)

This study describes the physical and chemical properties of 17 Afroalpine lakes (>2 m deep) and 11 pools (<2 m deep) in the Rwenzori mountains, Uganda-DR Congo, with the aim to establish the baseline conditions against which to evaluate future environmental and biological changes in these unique tropical ecosystems, and to provide the foundation for lake-based paleoenvironmental studies. Most Rwenzori lakes are located above 3,500 m elevation, and dilute (5–52 μS/cm specific conductance at 25°C) open systems with surface in- and outflow. Multivariate ordination and pairwise correlations between environmental variables mainly differentiate between (1) lakes located near or above 4,000 m (3,890–4,487 m), with at least some direct input of glacial meltwater and surrounded by rocky catchments or alpine vegetation; and (2) lakes located mostly below 4,000 m (2,990–4,054 m), remote from glaciers and surrounded by Ericaceous vegetation and/or bogs. The former group are mildly acidic to neutral clear-water lakes (surface pH: 5.80–7.82; Secchi depth: 120–280 cm) with often above-average dissolved ion concentrations (18–52 μS/cm). These lakes are (ultra-) oligotrophic to mesotrophic (TP: 3.1–12.4 μg/l; Chl-a: 0.3–10.9 μg/l) and phosphorus-limited (mass TN/TP: 22.9–81.4). The latter group are mildly to strongly acidic (pH: 4.30–6.69) waters stained by dissolved organic carbon (DOC: 6.8–13.6 mg/l) and more modest transparency (Secchi-disk depth: 60–132 cm). Ratios of particulate carbon, particulate nitrogen and chlorophyll a in these lakes indicate that organic matter in suspension is primarily derived from the lakes’ catchments rather than aquatic primary productivity. Since key features in the Rwenzori lakes’ abiotic environment are strongly tied to temperature and catchment hydrology, these Afroalpine lake ecosystems can be expected to respond sensitively to climate change and glacier melting.

Past and present human impacts on the biodiversity of Socotra Island (Yemen): implications for future conservation

Abstract The Socotra Archipelago (Yemen) is globally recognized for its outstanding biodiversity and endemism, designated on this basis a UNESCO World Heritage Site in 2008. The island underwent long geological and political isolation, ensuring preservation of unique ecosystems until the start of the new millennium. Now, Socotra Island is undergoing rapid development, out of balance with conservation. Major causes for biodiversity loss in other global insular ecosystems such as habitat fragmentation and degradation, pollution, invasive species and the impact of tourism, are becoming pressing issues that deserve close attention. Unsustainable resource use, the loss of traditional land management and illegal trade in biota are worrying phenomena that further increase the pressures on Socotra’s ecosystems. We provide the first comprehensive review of potential human impacts on Socotra before the 21st century, an updated discussion of some of the principal threats to its biodiversity in recent times, discussing local examples within a historical context of known extinction processes on islands, and underline the importance of traditional knowledge in the protection of Socotran ecosystems.

Adaptations to the hyporheic in Aloninae (Crustacea: Cladocera): allocation of Alona protzi Hartwig, 1900 and related species to Phreatalona gen. nov.

Morphological study of Alona protzi Hartwig, 1900, Alona phreatica Dumont, 1983 and Alona smirnovi Petkovski & Flößner, 1972 reveals close affinities with Alona labrosa Vasiljeva & Smirnov, 1969. We separate these four species from the polyphyletic Alona Baird, 1843 (Anomopoda: Chydoridae). United under Phreatalona gen. nov., these taxa share primitive features on the limbs, together with specializations to a rheic life mode. Phreatalona contains some of the only true hyporheic taxa within the Cladocera. Endemism in two ancient lakes (P. smirnovi and P. labrosa) and a preference for river sediments in Europe (P. phreatica and P.protzi) suggest a long isolation from typical littoral/benthic biotopes. We discuss close links with southern vicariant Nicsmirnovius, the position of these (hypo)rheic chydorids within the subfamily and their affinities with Acroperus. We remark an independent evolution of external (habitus, postabdomen) vs. internal (limb) morphology in the protzi-complex. Phreatalona is likely tertiary in origin, evolving from a littoral alonine adapting to rheic and finally hyporheic environments. Baikal endemic P. labrosa is likely the most primitive species of the genus. We discuss adaptations and evolution in the hyporheic and the effect on dispersal and biogeography of Phreatalona.

Redescription of Leydigia parva Daday, 1905 and assignment to Parvalona gen. nov. (Cladocera: Anomopoda: Chydoridae)

A morphological investigation of Leydigia parva Daday, 1905 (Chydoridae: Anomopoda: Cladocera), based on specimens from Paraguay (type specimens) and Brazil, clarifies its position in the subfamily and prompts its assignment to a new genus, Parvalona. The affinity of this rare benthic chydorid with Leydigia Kurz, 1875 and Alona Baird, 1843, in which this taxon was placed earlier, is discussed.

Rwenzori Mountains (Mountains of the Moon): Headwaters of the White Nile

The Rwenzori Mountains, Ptolemys legendary Mountains of the Moon, were created in the late Pliocene (less than 5 Ma bp) and stretch along the border between western Uganda and Democratic Republic of Congo. The landscape has been sculptured by repeated growth of glaciers, resulting in numerous lakes and six separate mountains rising over 4,500 m asl. Apart from being considered the (highest) source of the White Nile, the range is also renowned for its high level of endemicity, especially with regard to the terrestrial biota. In this chapter, we sketch the history of exploration, and summarize the main characteristics of Rwenzoris terrestrial and aquatic ecosystems. We also point out some highlights in the paleo- climatic history of the range.

New species in the rheophilous genus Nicsmirnovius Chiambeng & Dumont, 1999 (Branchiopoda: Anomopoda: Chydoridae) and reassignment of Alona eximia Kiser, 1948 and Alonella fitzpatricki Chien, 1970

A morphological comparison of specimens previously assigned to Alona eximia Kiser, 1948 from tropical Africa, Eastern Asia and the Americas shows that this species-group shares a number of morphological characters on the postabdomen, head pores, first antenna and second and fourth limb that separate them from Alona Baird, 1843 but unite them with Nicsmirnovius Chiambeng & Dumont, 1999. Alonella fitzpatricki Chien, 1970, formerly believed to be a junior synonym of A. eximia, is separated from the latter and assigned to the genus Nicsmirnovius. Two new taxa, from Africa and the Island of Socotra (Yemen) are added to the genus. The relationship between the specialised habitat of these chydorids and their morphology is discussed. The geographic range of all known populations is figured and a key to species is presented.

Fossil remains of an unknown Alona species (Chydoridae, Aloninae) from a high arctic lake in Nordaustlandet (Svalbard) in relation to glaciation and Holocene environmental history

We analyzed a lacustrine sediment core covering the Holocene from Lake Einstaken, Nordaustlandet, for its fossil Cladocera (Crustacea) with an aim to reconstruct past aquatic communities in this environmentally extreme and unexplored region. In the analysis, we encountered remains (carapaces, ephippia, headshields, and postabdomens) of an unknown chydorid (Chydoridae, Aloninae) species during two separate periods in the early Holocene. The remains had some comparable morphological characters with the European Alona guttata s.str. Sars, 1862 and with the glacial relict Alona werestschagini Sinev, 1999, but they differed clearly from the previous species; the headshield had broadly rounded rostrum and narrow fornices, the ephippium was heavily pigmented and reticulated, and the postabdomen had convex dorsal and ventral margins. The postabdomen had evidently similar morphology with Alona bergi Røen, 1992, which has been described, although inadequately, from arctic Canada and northern Greenland. We conclude, based on the morphology of the postabdomen, that the unknown remains belong to species closely resembling A. bergi, named here Alona cf. bergi, and assume that the species, whether the true A. bergi or some other cryptic species of the A.guttata group, is a postglacial relict of the high arctic adapted to cold climate. Herewith, we emphasize the need for extensive biogeographical investigations into both fossil and intact specimens of chydorids in the arctic.

A DROUGHT-RESISTANT LARVA OF PANTALA FLAVESCENS (FABRICIUS, 1798) (ODONATA: LIBELLULIDAE) IN THE LENÇOIS MARANHENSES, NE-BRAZIL

This paper is dedicated to Philip S. Corbet on the occasion of his 70th birthday. Abstract A single male of Pantala flavescens was collected by chance with dry mud in the bed of a pond in the Lenc ois Maranhenses (N-E Brazil) which had been dry for several months. It was noticed as a larva in an aquarium about seven days after the mud first had been wetted and it was then reared to the imaginai stage. Fifteen measurements were taken on three larval skins that could be recovered. These were fitted to literature data on larval development that had first been converted to exponential growth curves, in an effort to determine whether the drought-resistant stage had been an egg or a larva. It was found that that a drought-resistant egg was improbable, and that the larva had probably survived drought as an early instar (2–4). It is argued that early larval tolerance to drought may be common in Pantala, and may contribute as much to its success in semiarid environments as its rapid larval development.

Corrections and additions to the Dumontiidae Santos-Flores & Dodson, 2003 (Crustacea: Branchiopoda: Anomopoda), and implications for anomopod phylogeny

The presumed sixth limb of Dumontia Santos-Flores & Dodson, 2003 is shown to correspond to the inner part of the fifth limb. Comparison of the latter structure within the order increases the similarity between the Dumontiidae and the Daphniidae (plus Moinidae), but important similarities with the Radopoda remain. The relationship between a ‘‘daphniid line’’ and radopods needs further attention.