Water loss and viability in Zizania (Poaceae) seeds during short-term desiccation

How Texas wild rice, Zizania texana, became isolated in the San Marcos River of Central Texas, hundreds of kilometres from other wild rice populations is not known. Zizania seeds are intolerant of short-term desiccation. Seeds desiccated at 14% relative humidity (RH) and 75% RH do not survive after only 5-6 d and 2-3 wk of drying. Water loss is rapid and reaches a maximum at the time of seed death due to drying. And although all Zizania seeds germinate well following a long, cold dormancy period, Z. texana seeds readily germinate in the isothermic water (22°C) of the San Marcos River and Springs without an obligate, cold dormant period. Within 30-60 d of collection, Z. texana seeds germinate in substantial numbers, unlike seeds of Z. palustris, which require a long, cold dormant period. The Texas population of Z. texana may represent a relict population of a once more widely dispersed wild rice population, since the San Marcos springs probably have never gone dry.     

Eel community structure,fluvial recruitment of <Emphasis Type="Italic">Anguilla marmorata</Emphasis> and indication for a weak local production of spawners from rivers of Réunion and Mauritius islands

Anguillid eels were sampled from permanent rivers in the Réunion and Mauritius islands, western Indian Ocean, with a standardized electrofishing method. A. marmorata was very dominant, corresponding to 91.7 and 90.7% of all the eels collected in Réunion and Mauritius, respectively. Three other species (A. mossambica, A. bicolor bicolor and A. nebulosa labiata) were also present in both islands. A. marmorata showed a strong altitudinal gradient of densities from the lower to upper zones, especially in the younger stages (TL <250 mm), while A. mossambica was only found in the upper zones and A. bicolor bicolor occurred only in the lower zones (A. nebulosa labiata was rare). The eel species composition in freshwaters of both islands is very similar because these two adjoining islands are located in the same trail of drifting marine larvae. Mean estimated eel biomasses were noticeably low (11.1 and 22.2 kg ha⁻¹ in Réunion and Mauritius islands, respectively), especially when compared to those of other tropical insular systems without any eel fishery (Comoros or Polynesia, more than 100 kg ha⁻¹). Nevertheless, the fluvial recruitment of A. marmorata seemed to be regular during the surveyed period, staggering from October to April. The obvious lack of large eels in Mauritius but more significantly in Réunion suggests a high pressure from traditional fishery, and the local reproductive turnover is uncertain. Because sexual maturation seems to occur at a large body size for A. marmorata, as for temperate species, the Réunion and Mauritius rivers may only have a weak contribution to the regional production of spawners. However, the giant mottled eel population in the western Indian Ocean is believed to be panmictic at the regional scale, and may not rely exclusively on these islands’ contribution. A comparison is made with those of freshwater systems in other tropical islands.     

Heat coma and its relationship to ocean dynamics in the oceanic sea skaters of Halobates (Heteroptera: Gerridae) inhabiting Indian and Pacific Oceans

This study was performed to clarify how weather and current dynamics affect the resistance to temperature change in the oceanic sea skaters, Halobates. Heat coma temperature (HCT) was measured for the adults and 5th instar larvae of four Halobates species collected from a fixed sampling location (12°00′N, 135°00′E ) in western tropical Pacific Ocean and from 13 locations in the eastern area of the India Ocean ranging from 08°00′N-06°00′S and 86°00-76°00′E. Both the gap temperature for heat coma (GTHC, mean±SD: 7.83±1.86 °C, n=32) and the heat coma temperature (HCP, 35.03±1.80 °C, n=32) of individuals collected from the Pacific Ocean, during the first half (10 days) of the sampling period at the fixed sampling point, were significantly higher than those during the second half (GTHC: 5.10±2.05 °C, n=63; HCP: 34.03±2.02 °C, n=63). The reduction in heat tolerance shown in the second half of the 20 day period may have been caused by a decrease in air temperature due to rainfall that occurred around the sampling point accompanied with the arrival of Typhoon No. 6.In the study of individuals collected from the Indian Ocean, significantly higher average GTHCs of >8 °C were recorded for the adult H. micans collected at 02°00′S and 06°00′S (89°00′E) than those at 0°00-8°00′N in the eastern Indian Ocean. Dynamic mixture of water from northern and southern currents occurs at 02°00-6°00′S of the Indian Ocean and might relate to such high heat tolerance.Temperature dynamics in the ocean habitat might directly affect the temperature resistance of the oceanic sea skaters.     

Hybridization and barriers to gene flow in an island bird radiation

While reinforcement may play a role in all major modes of speciation, relatively little is known about the timescale over which species hybridize without evolving complete reproductive isolation. Birds have high potential for hybridization, and islands provide simple settings for uncovering speciation and hybridization patterns. Here we develop a phylogenetic hypothesis for a phenotypically diverse radiation of finch-like weaver-birds (Foudia) endemic to the western Indian Ocean islands. We find that unlike Darwin's finches, each island-endemic Foudia population is a monophyletic entity for which speciation can be considered complete. In explaining the only exceptions-mismatches between taxonomy, mitochondrial, and nuclear data-phylogenetic and coalescent methods support introgressive hybridization rather than incomplete lineage sorting. Human introductions of known timing of one island-endemic species, to all surrounding archipelagos provide two fortuitous experiments; (1) population sampling at known times in recent evolutionary history, (2) bringing allopatric lineages of an island radiation into secondary contact. Our results put a minimum time bound on introgression (235 years), and support hybridization between species in natural close contact (parapatry), but not between those in natural allopatry brought into contact by human introduction. Time in allopatry, rather than in sympatry, appears key in the reproductive isolation of Foudia species.     

Traditional Ecological Knowledge of a Riverine Forest in Turkana, Kenya: Implications for Research and Management

The present study explores traditional ecological knowledge (TEK) of Turkana pastoralists and cultivators in the context of a riverine forest in northern Kenya. The Turkwel River and its floodplain sustain a thick forest, which is used for grazing and extraction of non-timber forest products. However, sedentarisation and agricultural expansion have resulted in localised clear-felling of trees, while river damming has altered the natural flow regime. A series of structured, semi-structured, and group interviews were combined with a botanical inventory in order to assess the relevance of TEK to ecological research and forest conservation. Turkana informants gave 102 vernacular names for the 113 woody species. Of these, 85% had a domestic or pastoral use among the 105 specific uses that were described. Ethnobotanical knowledge was relatively homogenous and not related to age, gender, or source of livelihood. The informants had in-depth knowledge of some key ecological processes. The conceived threats to forest survival were primarily cultivation and permanent settlements, while the effects of river damming and livestock grazing were disputed. A claimed decline in rainfall was confirmed by official data. There is strong evidence that TEK could be used to generate hypotheses for research and to design sustainable conservation strategies. A revised version of the indigenous system of tree management should be incorporated into the official forestry policy in order to resolve future conflicts between pastoralists and cultivators.     

A new genus and species of deep-sea glass sponge (Porifera, Hexactinellida, Aulocalycidae) from the Indian Ocean

New hexactinellid sponges were collected from 2589 m depth on the Carlsberg Ridge in the Indian Ocean during deep-sea dredging. All fragments belong to a new genus and species, Indiellagen. n.ridgenensissp. n., a representative of the family Aulocalycidae described here. The peculiar features of this sponge, not described earlier for other Aulocalycidae, are: longitudinal strands present in several layers and epirhyses channelization.     

韩国华津浦湖的鱼类区系

There are sevenlagoons onthe east coast of Korea,including Kyeongpo Lake,Hyang Lake,Mae Lake,Chung-cho Lake,Yeoungrang Lake,Songji Lake and HwajinpoLake.They are all originally natural and brackish waterlakes.Therefore,these lakes are not only historically veryimportant but also have high values for geological,andecological sciences.Natural lakes like lagoons are different from man-made lakes.That is,water level in natural lakes is almostconstant,cline by waterside is not much,and wet la…     

Length–weight relationships of seven fish species in the Yangtze River Estuary and its adjacent waters,Eastern China

The length–weight relationships (LWRs) for seven fish species belonging to five families in the Yangtze River Estuary and its adjacent waters are presented. Cynoglossus gracilis, Cynoglossus macrolepidotus, Ctenotrypauchen chinensis, Collichthys niveatus, Ophichthus apicalis and Erisphex potti were collected monthly in 2009 using trammel nets (the size of smaller mesh net was 1.5 m × 15 m × 4 panels with mesh sizes of 2.5, 3.4, 4.3 and 5.8 cm; the size of larger-mesh net was 2.4 m × 30 m × 4 panels with mesh sizes of 5.0, 6.0, 7.0 and 8.0 cm; soaking overnight). Lophiogobius ocellicauda were collected December in 2020 using shrimp trawl nets (mesh size 2.0 cm). The precision of measurement for the fish specimens is 0.1 cm total length and 0.1 g total weight. The estimated ranges of the parameters a and b for the seven fish species were from 0.0001 to 0.0289 and 2.718 to 3.541, respectively. Two new maximum total length were recorded for Ctenotrypauchen chinensis and Ophichthus apicalis.