Rocky Banks Research Articles

A fishery-independent assessment of an overfished rockfish stock, cowcod (Sebastes levis), using direct observations from an occupied submersible

A meaningful assessment of cowcod (Sebastes levis) has been conducted using visual, nonextractive, habitat-specific methods. Following the precipitous decline of rockfish (Sebastes spp.) stocks along the Pacific coast, it was evident that more effective methods were needed to assess several species in untrawlable habitats. Cowcod were surveyed within large Cowcod Conservation Areas (CCAs) off southern California using direct observations from the research submersible Delta over eight major offshore rocky banks in depths of 74 to 322 m. Maps of seafloor substratum and bathymetry were used to identify and quantify these areas. A line-transect analysis of fish counts, perpendicular distances of fish from the track line, lengths of survey tracks, and area of each rocky bank was used to estimate abundance. Biomass, calculated from abundance, fish length, and a weight–length relationship, varied with mean size of cowcod on these banks. These fishery-independent results have contributed to the recent assessment of cowcod by the Pacific Fishery Management Council. A time series of results from visual surveys is now necessary to evaluate a trend in cowcod biomass with respect to increased time of protection within the CCAs.

Habitat characteristics of juvenile cowcod, Sebastes levis (Scorpaenidae), in Southern California

We characterized habitat requirements of juvenile cowcod, Sebastes levis, using information from surveys conducted aboard the manned research submersible Delta. We conducted 303 dive surveys on rocky banks and outcrops in water depths between 28 and 365 m in southern and central California, covering 483 km (963,940 m2) of seafloor. We counted 549,263 fishes from at least 134 species; 216 individuals were juvenile cowcod, S. levis, of 45 cm or less in total length (TL). Juvenile cowcod occupied depths between 52 and 330 m and demonstrated ontogenetic shifts in their habitat associations. Small fish (5–20 cm TL) lived primarily among cobbles or cobbles and small boulders. As fish grew, they moved into high-relief rock habitats, including boulder fields and rock ridges. Small cowcods were found with pygmy, Sebastes wilsoni, and swordspine, Sebastes ensifer, rockfishes. Larger juveniles often associated with juvenile bocaccio, Sebastes paucispinis, juvenile widow rockfish, Sebastes entomelas, and squarespot rockfish, Sebastes hopkinsi. Our study resulted in a characterization of seafloor habitats on a small spatial scale that is relevant to juvenile cowcod nursery areas, which is important when considering effective management strategies for this overfished species.

An Improved Technique for Small‐Scale Radio‐Tracking of Crayfish and Benthic Fishes in Upland Streams

AbstractThis study measured the accuracy of two radio‐tracking techniques: (1) triangulation using a Yagi antenna and (2) a form of direct location, the extended‐reach technique, which uses a small loop antenna attached to a lightweight 9‐m telescopic pole. The study was conducted in the Cotter River, an upland stream in the Australian Capital Territory. Radio tags were positioned instream to determine whether depth, substrate, or local bank profile affected radio‐tracking accuracy. The extended‐reach technique was more accurate (mean error ± SE = 1.00 ± 0.21 m) than triangulation (2.57 ± 0.21 m). Decreased accuracy resulted from the triangulation of radio tags positioned close to boulders or in water more than 1 m deep. These variables had no effect on the accuracy of the extended‐reach technique. The presence or absence of a steep rocky bank did not affect the accuracy of either radio‐tracking method. The increased accuracy of the extended‐reach technique provides an improvement over traditional methods for studying the small‐scale movement and microhabitat use of crayfishes (e.g., Eustacus spp.) and benthic fishes in upland streams.

Geology - benthos relationships on a temperate rocky bank, eastern Bass Strait, Australia

To better understand the possible relationships between the geology of the seabed and the associated biological communities, a multibeam sonar survey over New Zealand Star Bank in the eastern Bass Strait was conducted. A hierarchical method of benthic habitat mapping was applied to the secondary biotope and biological facies levels at the site (<10 km) scale. Four secondary biotopes and four biological facies have been defined on the basis of geomorphology revealed by the bathymetry model and the results of statistical analysis of the sediment and underwater video transect data over the bank. The major differences that control the distribution of biological communities in the New Zealand Star Bank area appear to be related to variations in substrate. (1) Hard-ground features related to high-relief granite outcrops are associated with diverse and abundant sessile and motile fauna. These faunal communities may be biologically modified to patchy barrens habitat by grazing urchins. (2) Unconsolidated sediment on a flat seabed is associated with sparse small sponges on the inner shelf. On the middle shelf and seaward of bank, the flat and muddy seabed supports a community dominated by infauna. (3) Unconsolidated sediment on a low-relief seabed is associated with an increase in the density and sizes of sponges concentrated on any low-relief feature raised above the surrounding flat seabed.

A new cleaner goby of the genus Elacatinus (Teleostei: Gobiidae), from Trindade Island, off Brazil

Elacatinus pridisi n. sp., a cleaner goby from Trindade Island, off Brazil, differs from its congeners of the Horsti Complex that have a pale stripe extending from the eye to the caudal fin base by the following combination of characters: dark longitudinal stripe wide, reaching lower abdomen and base of anal fin (vs. never reaching lower abdomen or base of anal fin in all other species); pectoralfin rays typically 18 (vs. typically 17 in E. randalli (B hlke & Robins) and E. figaro Sazima et al. and typically 16 in E. atronasum (B hlke & Robins)); anal-fin rays typically 11 (vs. typically 10 in E. figaro); a pale oval spot present on snout (vs. no spot in E. atronasum and E. horsti (B hlke & Robins), a "V"-shaped spot in E. prochilos (B hlke & Robins), and a medial bar in E. xanthiprora (B hlke & Robins), E. louisae (B hlke & Robins) and E. lori Colin). The new species was recorded in depths ranging from 3 to 30 m, over rocky reefs and calcareous-algae banks around the island. It has been observed in cleaning activities during the day with clients varying from large-sized carnivores such as Carcharhinus perezi (Poey) to small-sized planktivores such as Chromis multilineata (Guichenot). The discovery of the new species reinforces recognition of the Trindade-Martin Vaz insular complex as an area of endemism in the Atlantic Ocean.

Ex situ conservation of Dyckia distachya: an endangered bromeliad from South Brazil

The Brazilian Atlantic Forest biome contains a high level of genetic diversity. Historically, several factors have contributed to the drastic reduction of its cover, today restricted to less than 7%. Large forest areas have been cut down in t he states of Santa Catarina and Parana to make way for hydroelectric power plant dams and many plant species are threatened to various degrees, especially the endemic. This is the case of the Dyckia distachya bromeliad, native to the rocky banks of the River Uruguay that is threatened with extinction because of the construction of a dam for the Ita Hydroelectric power plant. The present study describes the plant's most relevant characteristics and the results of ex situ and in vitro conservation. Plants and seeds were colleted and established ex situ in the bromeliad germplasm bank. Seeds were germinated in the laboratory and the resulting plants conserved in vitro using the growth reduction technique. Both methodologies were considered effective for germplasm conservation.

New data on occurrence of thermophile Scleractinia (Cnidaria, Anthozoa) in the Phlaegrean Island (Ischia, Procida, Vivara, Gulf of Naples), with special attention to Astroides calycularis

Biogeographia vol. XXV - 2004 (Printed December, 30 q' 2004) Marine Biogeography of the Mediterranean Sea: patterns and dynamics ofbiodiversity New data on occurrence of thermophile Scleractinia (Cnidaria, Anthozoa) in tl1e Phlaegrean Islands (lschia, Procida, Vivara, Gulf of Naples), with special attention to /lstroicles cal)/cu/arts MARCO DAPPIANO°*, MARIA CRISTINA GAMBI* ° [CR/LM, via dz’ Czzsrzlotti 300, Roma (Italy). Ttzborzztario di Ecologirz del Bent/705, Stzzzione Zoologiaz qA. Do/7m ”, Pzmtzz San Pietro —./380077 Isc/7221 (Nzzpoli, Italy) Key words: Scleractinia, Afiroitler a1/you/zzrir, distribution, marine cave, Tyrrhenian Sea. SUMMARY Ntw data on occurrence and distribution of some Scleractinia (Cnidaria, Arithozoa) with thermophile affinity were presented for the area comprising the Phlaegrean islands (lschia, Procida and Vivara, Gulf of Naples Tyrrhenian Sea). Data were obtained by means ofvisual census and photographic sampling in 21 sites located all around the islands on rocky cliffs, rocky banks and semi-obscure caves. Four species with thermophile affinity were recorded: Clzzdocorzz czzerpitarzz (Linneo, 1767), Mzzzlraa‘.tp/rzzmzsis (Heller, 1868), P/Jyllzmgzlz mom:/aezii (Lacaze—Duthiers, 1897), and Artroides mlym/izrir (Pallas, 1766). Both M. plmremir and P. mozrr/Jezii were first reported for the studied area after our study. The most widespread and frequent species was C raertaitara, occurring in almost all studied sites in photophilious biotopes within the first 15-20 m depth. M. 127/1zzremz': was particularly abundant in the “Grotta Grande” of the bank “Formiche of Vivara”, where it formed a large flzcie: on the cave ceiling. P. mam‘/Jezii was the most occasional specie occurring with few colonies in three sites between 25 and 40 m depth. For A. nzlycztlrzris a specific study on abundance pattern and population structure was performed in three stations (two inside of a semi—submersed, semi—obscure cave and one along the shadowed cliff off S. Angelo). A. czzlyrztldrzk showed very high densities in the zone 0-1 m depth, mainly consisting of young specimens (1—3 corallites). Density showed a dramatic decrease below 3 m depth in the two stations inside the cave, while in S. Angelo density started to decrease below 6-8 m depth. Inside of the cave, comparison with previous observations from an earlier ecological study performed in 1976, revealed that the species has strongly increased its abundance and coverage, extending its colonization to the entire perimeter of the cave, including a long and narrow siphon and a large inner chamber (from approx. 56 ml of bottom colonized in 1976 to approx. 418 m” in 2003). The high frequency, and extension of/1. m{yt‘zz/zzri: in the studied area can be favored by changes in the hydrographic conditions in the southern Tyrrhenian Sea and in the Gulf of Naples. In fact, an overall slight warming of the superficial waters has been recorded in some periods in the Gulf. Longer water mass summer stratification and increase of winter minimum were occasionally recorded. This inter—annual variability, with some years or longer periods of warming of the superficial waters, may be an important factor for the reproductive success of the species, which in these periods can favor more intensive offspring production and increase successful settlement of new recruits that may lead to the increased colonization observed. A. rzzlym/zzrir, especially in those areas such as the Gulf of Naples near to its northern distribution limit, should be therefore considered as a good “biological indicator” at short and rnedium—term scale, to reveal ongoing climatic changes.

Clear Creek

over, and that following summer had been the hardest for her since Darrell died. Mice! Mischief makers! Ever since, she had been careful to put poison in the attic. She had had no more problems with mice. Clear Creek My mommy said the creek never runs dry. My uncle said, no, never, not in his life time or their father's before them. Rest his soul in heaven, that creek never runs dry. Water so clear from riding on the back of that dark, gray slate, So slick that the water just glides like sheets of ice. It runs over naked fossils of coral and hard rounded géodes unbroken, Holding back crystals still growing in their entombed bellies. The sycamore trees hang close to Clear Creek Roots spread, nestled tight to the rocky bank Like ladies dressed in gowns, spread out in display In the summer wearing their fancy best. Bosoms full of heavenly beauty. Clear Creek never runs dry, No sir, never that we know. —Marilyn Gabriel 61 ...

A Good Boy, Bradley

FICTION A Good Boy, Bradley Laura Weddle It was the first day ofJuly and hotter than blazes. Nellie Grimes sat on her front porch, rocking, and breaking the last of the summer's beans. Her knotted little claw-like hands worked with mechanical precision, almost independently of her mind and body. As she worked, her eyes darted around the yard, taking in the sagging front gate, the broken bottom porch step, and the weather-beaten mailbox leaning drunkenly to one side. She could count at least six things that needed fixing in the front yard alone, never mind the back yard and the barn. She was trying to figure out a way to get her nephew Bradley to come up and do some work for her. He was just fifteen, but big and strapping like his daddy, and a good hard worker. Not too smart, as far as she could tell. Had a faraway, meandering look about his eyes that sometimes made her wonder if there was anybody home. Nellie was alone, and had been for so long she hardly even noticed it anymore. Mr. Ben had let her stay on in the tenant house after Spencer died ten years ago. Then when his granddaughter, Nora, inherited the farm, she had never asked Nellie to move either, and all they ever expected was for her to keep things up in reasonably good repair. That never had been a problem until just the last couple of years. Hard work was as natural as walking or breathing, but lately the pains in her hip joint made it hard to get up when she was down, much less fix a broken gate or plant a mailbox post. So she sat there and plotted and schemed about how to get Bradley to come and do the chores, without having to pay him an arm and a leg. It was ridiculous. The boy wanted five dollars for every day's work he did around the place, and him her blood kin. Nellie had a good view of the road and fields around the farm, situated as she was on a little rise, and her porch another ten feet off the ground. A dark green line of trees over to the right stood like sentinels between her house and the rocky banks of Harrison Lake. Laura Weddle, Somerset, Kentucky, is a retired Pikeville College professor, andfreelance writer. 38 The county road ran by in front of her house, and most weekends during the summer, a stream of cars pulling boats or trailers would head for the cool shelter of camping and fishing sites on the lake. She had almost finished breaking the beans when she saw dust rising, a long way down the road. She watched idly as the cloud came closer to her gate, and when it moved past, she saw that it had been raised by a big black car she'd never seen before. Nellie squinted to try to get a better view. She set the pan of beans aside and eased up to walk over to the porch railing. "Ohhh," she breathed, and rubbed her hip. She held on to the back of the rocker, and stretched out her other arm to catch the rail. Above all things she dreaded the thought of falling, alone as she was out there. The car had passed her gate and gone on down the road, obviously in a hurry to get somewhere. Nellie was about to turn around to get her beans and take them into the kitchen, when she saw the car stop in the road and two men in dark suits get out. Now what on earth are they stopping out here for? she wondered. They sure weren't fishermen, and there wasn't much to see around here, at least nothing worth stopping a car for. She was puzzling it over when a curious thing happened. The two men looked up toward her house, then turned to face each other. From where she stood, they appeared to be arguing, and although she could not hear words from that distance, she had the impression that the discussion was heated. While she stood peering...

Ecology of Cichla (Cichlidae) in Two Blackwater Rivers of Southern Venezuela

We investigated the ecology of peacock cichlids (Cichla spp.), diurnal piscovores and important gamefishes, in the Rio Cinaruco (Rio Orinoco drainage of the southern Venezuelan llanos) during the dry seasons of 1992-1993 and the Rio Pasimoni (Rio Negro-Amazonas drainage) during early 1993. In the Cinaruco, three Cichla species partitioned available habitats: C. intermedin near structure in primary river channel within or near swift current, C. orinocensis in shallow water along the shoreline of lagoons or slow channel reaches, and C. temensis in deeper waters along sandbanks and steeper rocky banks of lagoons and the river channel. During the dry season, C. orinocensis and C. temensis fed heavily on small characiform fishes, and C. intermedin consumed a variety of fishes, including loricariid catfishes. Only two peacock cichlids, C. orinocensis and C. temensis, were found in the Pasimoni, a more acidic and less seasonal ecosystem. These two species were larger in the Pasimoni compared with Cinaruco conspecifics; however, conspecifics from the two locations conformed to similar mass-length relationships. In both river systems, C. temensis were significantly larger than congeners, and C. temensis consumed larger prey than congeners in the Cinaruco. Examination of gonads and sizes of intraovarian oocytes indicated that reproduction by all five populations probably is initiated during the late low water period and may continue into the flooding period. Investigamos la ecologia de los pavones (Cichlidae, genero Cichla), picivores diurnos importantes en la pesca deportiva, en el Rio Cinaruco (cuenca del Rio Orinoco en el sur del estado Apure, Venezuela) durante la sequia de los alios 1992-1993, y del Rio Pasimoni (cuenca Rio Amazonas, estado Amazonas) de Venezuela durante los primeros meses del 1993. En el Cinaruco, tres especies de Cichla reparten los habitat disponibles: C. intermedin se ubica cerca de cobertura (arboles sumergidas, etc.) en el cauce principal cerca 0 dentro de la corriente rapida; C orinocensis se

Distribution and status of the smooth-coated otter Lutra perspicillata in National Chambal Sanctuary, India

The distribution and relative density of smooth-coated otters Lutra perspicillata Geoffroy were studied along a 425 km stretch of Chambal river within the National Chambal Sanctuary, Central India, between 1988 and 1992. Sample sites of 1 km were surveyed every 5 km. The study revealed that the distribution of otters along the river is patchy and largely restricted to the upper reaches. During the 1988 survey, 36% of sites were found with otter signs but only 24% in 1992. Recent increases in disturbance along the river due to construction of road bridges and mining activities might have put pressure on the population. Most of the positive sites (66%) were found on rocky banks, followed by clay banks (19%), banks with shoreline vegetation and marsh (11%) and sandy banks (3%). During intensive monitoring of four radio-implanted otters, c. 78% locations were made on rocky banks, 19% on banks with shoreline vegetation and marsh, with < 3% on sandy banks and <1% on clay banks, indicating greater preference for rocky banks owing to the greater availability of den sites. As a conservation measure, monitoring of the otter population should be done regularly and restrictions on cultivation, grazing and mining along the banks should be imposed within the Sanctuary limits, especially in the identified stretches.

Distribution and habitat of the spotted tree-frog, Litoria spenceri Dubois (Anura : Hylidae), and an assessment of potential causes of population declines

An extensive survey of the distribution and abundance of the spotted tree frog, Litoria spenceri, was conducted throughout its range in the Central and Eastern Highlands of Victoria and parts of New South Wales and the Australian Capital Territory between November 1991 and April 1994. Of the 64 streams surveyed, Litoria spenceri was recorded along 16, 15 in Victoria and one in New South Wales. The species was located along six streams in which it had not been recorded before, but could not be found along four streams in which it had previously been recorded. The survey failed to detect L. spenceri at historical sites on four other streams but located it elsewhere along those streams. Frogs were located predominantly in association with rocky banks adjacent to fast flowing water. Most populations occurred in dissected mountainous country, generally in areas with limited access and disturbance. Analysis of disturbance histories at individual sites and within catchments supporting the species indicates an association between the contraction in distribution and a number of human disturbances to forest and riparian habitats.

New azonal syntaxa from the hills and river banks of the Manyeleti Game Reserve, Northern Transvaal Province, South Africa

As part of a vegetation survey programme for nature conservation areas in South Africa, surveys of the plant communities of the rocky outcrops and river banks in the Manyeleti Game Reserve were undertaken. The Cardiospermo corindii-Acacietalia nigricentis are restricted to quartz and gabbro hills, mainly on shallow, soils, whereas the Spirostachyo africanae-Diospyretalia mespiliformis occur on the banks of small dry rivers. From a Braun-Blanquet analysis of the vegetation of the rocky outcrops and the riparian vegetation, two new orders, two new alliances and six new associations were identified and described. Additionally a quantitative assessment of the woody component of each association is presented. Ordinations based on floristic data revealed the position of the syntaxa on an environmental gradient.

The ecology and conservation of the Killarney Fern Trichomanes speciosum willd. In Britain and Ireland

Trichomanes speciosum Willd. (Hymenophyllaceae) is one of the rarest and most celebrated species in the British and Irish vascular flora. The ecology and habitats of 43 colonies of the sporophyte (fern plant) generation are described. Two-way indicator species analysis suggests that T. speciosum occurs in four main floristic groups; in very deeply shaded habitats; in large dripping caves; in crevices in cliffs and small caves; and on dripping vertical cliffs and rocky banks in wooded ravines. Canonical correspondence analysis shows that altitude and habitat types are the major environmental variables influencing the floristic composition of the 43 colonies. Monitoring data suggest that frond number remains remarkably constant over 13–29 years. Possible reasons for the absence of T. speciosum in so many apparently suitable habitats in western Britain and Ireland are discussed. Sporophyte establishment appears to be most critical, especially under a climate that is marginal for its temperature requirements. The distribution pattern of T. speciosum and its ability to colonise man-made habitats in northern France but not in Britain or Ireland suggest that some factor associated with temperature may be limiting. As each colony may consist of one or two individual plants with many fronds arising from the rhizome mass, there are only about 50–100 plants of the sporophyte generation known in Britain and Ireland. There is thus a need to protect all remaining colonies in the British Isles from interference, especially collecting and habitat alteration. Extreme discretion with information about localities is essential. Translocation and re-stocking in the wild are only considered appropriate in special circumstances.

Creation of bases for the hydromechanics of rocky banks

Creation of bases for the hydromechanics of rocky banks

A New Species of Tillandsia (Bromeliaceae) from Northwest Argentina

A new species, Tillandsia (subg. Anoplophytum) guasamayensis (Bromeliaceae) from northwest Argentina is described and illustrated. Included are keys to a group of five, putatively related taxa within the subgenus. The new species differs from others in the strikingly purple floral bracts of intermediate size (3.0-3.5 cm long), the white petals to 4.0 cm long, and sepals that are 1.8 to 2.5 cm long. Tillandsia subg. Anoplophytum (Beer) Baker, an epiphytic/saxicolous taxon based in eastern South America (e.g., Castellanos 1945; Smith 1943), includes 34 species in the view of Smith and Downs (1977). Recent field research by one of us (Palaci) revealed the presence of a new species in this subgenus, having dark purple floral bracts, white petals, and sepals 1.8 to 2.5 cm long; i.e., features unlike those of any pu- tatively closely related anoplophyton species, such as T. friesii Mez. The plant grows near Til- cara, Jujuy, along the rocky banks of the Rio Guasamayo, together with Abromeitiella lorentz- iana (Mez) Castell, T. diaguitensis Castellanos (see note following description), T. capillaris Ruiz Lopez & Pavon, and species of cactus. The floral bracts are distinctive from T. friesii (known, for example, from the adjacent state of Salta at Que- brada del Toro, 100 km from the collection site of the new species, Fries 828 (S, TYPE), and from

Sphaerobambos, a New Genus of Bamboo (Gramineae-Bambusoideae) from Malesia

In preparing an account of the bamboos of Sabah, East Malaysia, I was unable to decide to which genus one sterile specimen (Tiong SAN 88660) belonged. It was collected from Lohan village near Ranau. In 1979 when I went collecting around Ranau, I did in fact see bamboo clumps on a small hill near Lohan village but made no collections; from a distance this bamboo looks like Schizostachyum blumei Nees or S. latifolium Gamble which are common in the area. In February 1986 I revisited the areas near Telupid and Ranau together with Mr P. S. Shim (SAFODA) and Mr K. M. Wong (then of FRIM, Kepong). We stopped and collected the bamboo I saw in 1979, in a sterile state; it matches Tiong SAN 88660. I still could not place it in any known genus. It is a scrambling bamboo; the culm has thin walls and the branches are many at each node with the primary branch dominant. These primary branches are not always dormant, some developing and elongating to become as large as the main culm and behaving like it by producing branches at each node. The sheaths of young culm-shoots and of young primary branches are hairy and have very narrow, almost inconspicuous rugose bases. The plant looks like a species of Dinochloa, but the culms do not climb and are only slightly zig-zag. Later on that day we came to the muchdisturbed Lohan River, and found near the rocky river bank a bamboo clump about m tall with a few erect culms and with flowers and fruits. This matched the sterile bamboo collected earlier. The inflorescence is composed of pseudospikelets, the spikelet consisting of several florets like that of Bambusa. The fruit is globose with a large embryo resembling that of Dinochloa but the plumule and radicle are basal rather than lateral. The palea is longer than the lemma in the mature spikelet, 2-keeled with narrow wings along the keels such as can be found in some species of Guadua from the New World. The anthers have apiculate tips. Later I found that one of the leafy branches of the first collection bore a young inflorescence. These features indicate that this bamboo belongs to an undescribed genus which I propose to name Sphaerobambos, with S. hirsuta as the type species. Sphaerobambos is apparently related to Dinochloa and Melocalamus by the structure of the fruit. It differs from both genera in having multi-flowered spikelets. Without fruit Sphaerobambos can be easily confused with Bambusa by having multi-flowered spikelets. It differs from the latter, however, by having the palea longer than the lemma and the keels of the palea winged (Table 1). The examination of other specimens from neighbouring islands deposited in the Herbarium at

Organization of a community of tadpoles in rain forest streams in Borneo

ABSTRACTSamples of 29 distinct larval forms of anurans were collected in streams flowing through primary rain forest at Nanga Tekalit, Sarawak, at three periods spaced over 22 years. This assemblage of tadpoles lives in torrents, riffles, shingle areas, open pools, leaf drifts, protected side pools, potholes in rocky banks, bank seepages, and pools of small intermittent streams. Positive associations of species in types of microhabitats and co-occurrence within sites lead to recognition of four taxonomically heterogeneous groups: one concentrated in leaf drifts; one using riffles, shingle areas, and open pools; one concentrated in potholes; and one using side pools and potholes. Most pairs of larval forms having strong negative association are characterized by differences in morphology and feeding behaviour; they show little evidence of competitive relations. Between-sites variation in species composition differs among the types of microhabitats, leaf drifts showing the least amount of variation. Species composition within a site shows less change over intervals of 1–5 days than over intervals of 13–18 days. Variation in species composition is greater between sites than within sites over intervals of 9–31 days. Organization in this community seems to be effected by three factors: reproductive behaviour of adults and morphological and behavioural adaptations of tadpoles.

Répartition transversale des macroinvertébrés benthiques dans un bras du Rhône

While the downstream distribution of benthic macrofauna has been studied in many rivers, its transverse distribution remains rather unknown. The present work concerns this problem in a semi-regulated arm of the Rhone. The characteristics of this arm are: width 80 m, depth 0.5 to 1 m in the section studied, pebble substrate, rocky banks, discharge regulated at 30 m3. s-1 except for floods up to 1 000 m3. s-1.

Germination Responses of Anisacanthus wrightii (Torr.) Gray (Acanthaceae) to Selected Environmental Variables

Anisacanthus wrightii seed germination and radicle growth were greatest at 35° C and both rapidly decreased at temperatures above 35°C. Seeds germinated equally well in light and dark and had no after-ripening requirements. Treatments which decreased water availability sig- nificantly reduced germination and radicle length. Germination percentages and radicle growth of seeds in aqueous media were not significantly different between pH 4 and 7 but were significantly reduced at pH values of 8 and 9. Germinability of Anisacanthus wrightii seeds decreased rapidly after 33 months dry storage and the seeds did not germinate, during a 10-day test period, after 42 months. Anisacanthus wrightii (Torr.) Gray (Acanthaceae) is a multi-branched shrub occurring on fertile soils of South Texas thickets, on rocky banks and flood plains of streams in the Edwards Plateau of Texas (Correll and John- ston, 1970), and in northeastern Mexico (Vines, 1960). The flowers are borne singly or in pairs in unilateral spicate inflorescences and are subsessile to MATERIALS AND METHODS.-Wright's anisacanth seeds used in this study were obtained from a mixture of seeds from approximately 300 plants at the Soil Conservation Service Plant Materials Center at Knox City, Texas. Wright's anisacanth plants at Knox City were grown from seeds col- lected from a natural population of plants near Waco, Texas. Seeds used in this study were harv- ested in 1976 and 1978. The 1976 accession was used to determine the length of seed viability and the 1978 accession was used for all other experiments. Seeds were stored at room temperature (24°C ± 3°) until used in experiments. Germination studies were conducted using 10 replications of 25 fully developed and undamaged seeds each in 10-cm diameter petri dishes. Two Whatman No. 3 filter papers saturated with 8 ml of distilled water or various test solutions were used as the germination substrate. The petri dishes were randomly arranged on moist paper toweling in a sealed glass box inside an environmental chamber for testing. Preliminary germination trials indicated no significant increase in germina- tion percentage between 10 and 30 days when seeds were subjected to constant temperatures of 25°, 30°, or 35°C. Therefore, cumulative percent germination and radical lengths were recorded at the end of 10-day test periods. Seeds were considered to have germinated when the radicle was at least 3 mm long. Each experiment was repeated one to three times and the data pooled.