Invertebrate communities,sediment parameters and food availability of intertidal soft-sediment ecosystems on the north coast of British Columbia,Canada

ABSTRACT

The Skeena River estuary supports commercial and culturally important salmon fisheries. However, considerable development has occurred in the area, and more has been proposed. If anthropogenic development degrades this critical habitat, the Skeena salmon run, that every year contributes $110 million to local economies, may be negatively impacted. Benthic invertebrates are common indicator species, as they often respond to disturbances before commercial species, warning of potential impacts. Unfortunately, invertebrates in the Skeena estuary have not been extensively studied, and we lack the detailed understanding of their community structure and dynamics for them to serve as indicator species in this region. Therefore, present conditions of the Skeena estuary are established here (invertebrate community, sediment conditions and food availability), in order to provide the data required both to anticipate changes associated with potential anthropogenic disturbances and to detect changes in this system if development occurs.     

XLIX.—A list of New Zealand Heteroptera with the description of a remarkable green Aradid representing a new genus

Summary

Christchurch Harbour is the lagoonal estuary of the Rivers Avon and Stour. Due to the low tidal range much of it remains submerged at low water. The microfauna living on the bottom sediment includes Foraminiferida and Thecamoebina. The latter are normally restricted to the lower reaches of rivers but when low salinity conditions prevail in the lagoonal part of the estuary they have a wider distribution. It is shown that a number of species will tolerate brackish water if the calcium content is less than 1 mg-atom/l. Most species show seasonal changes in abundance related partly to temperature changes. It is suggested that fossil Thecamoebina may be more common than has previously been recognized, especially in Pleistocene and Holocene deposits, and that they would be useful paleoecological indicators.     

Three new species of Gammarus from Shaanxi,China (Crustacea: Amphipoda: Gammaridae)

Three new species, Gammarus shenmuensis n. sp., G. murarius n. sp. and G. martensi n. sp. are described, based on the collections from the Shaanxi Province of China. The morphological characters that distinguish these different species are presented. Distribution data on these gammarids are also given.     

II.—Bermudian species of Donatia (Tethya)

Summary

Acanthochondrites inflatus (Bainbridge, 1909), parasitic on the branchial cavity wall of Raja radiata is redescribed and a comparison of its morphological features is made with the only other species of the genus, A. annulatus (Olsson, 1869.)     

Potential impacts of logging on intertidal infaunal communities within the Kitimat River estuary

ABSTRACT

Efficiently evaluating industrial activities plays an essential role in determining the extent to which human–ecosystem interactions may lead to species loss, disrupted community dynamics, and degraded ecosystems. Intertidal habitats offer a unique opportunity in this regard, as they are species rich ecosystems that exhibit rapid community turnover and pronounced responses to ecological disturbances. In an attempt to use these dynamic communities to identify the impact storage of harvested logs is having on the Kitimat River estuary, surveys evaluating the biotic and abiotic conditions within surrounding mudflats were conducted. The intertidal mudflats of the Kitimat River Estuary varied spatially and temporally, and with differences in the infaunal community, as well as the abiotic sediment conditions between reference mudflats, and mudflats potentially impacted by logging activities. While these differences were pronounced, we cannot at this time link these differences to the logging activities at impacted sites. We also observed evidence that suggests that the infaunal community of these intertidal mudflats have changed substantially since the 1970s, with the establishment of a community of polychaetes, as well as the appearance of the invasive clam Mya arenaria, and the invasive Cumacea Nippoleucon hinumensis. Beyond contrasting impacted and reference mudflats, the current health of these mudflats, as indicated by the infaunal community assemblage, is currently unclear. More research is required to determine if organic enrichment has occurred at these habitats, as well as to further elucidate the current health of these intertidal mudflats.     

Chelodesmid studies. XVIII. On some new or poorly-known taxa in the tribe Batodesmini (Polydesmida: Chelodesmidae)

Summary

Some new and poorly-known taxa of batodesmine diplopods are described from northern South America, with notes on their affinities. New genera include Igaraparana, based on I. batesi, sp. nov. from Amazonian Colombia; Curimagua, based on C. granulata, sp. nov. from Edo. Falcon, Venezuela; and Cheirogonus, based on C. pittieri, sp. nov. from Panama. The inadequately proposed species Leptodesmus interrupticolor Silvestri (southeastern Ecuador) is redescribed and figured from type material, and referred to Cordilleronomus as its third species. The enigmatic genus Tunochilus Chamberlin, 1950, is clarified and referred to the Batodesmini from its incorrect location in the Cryptodesmidae, with notes and drawings made from a paratype of the type species T. marginis; the presumptive congener T. marcuzzii is described as new from material taken at Caracas, Venezuela.     

Biogeography of amphipods (Crustacea: Amphipoda: Gammaridae) from the central Zagros Mountains,Iran, with descriptions of two new species

Seven species of gammarid amphipods were studied in the relatively small province of Charmahal-Va-Bakhteyari in the central Zagros Mountains, Iran. Of these, four are previously known (Gammarus proiectus, G. komareki, G. syriacus and G. balutchi), one is a new record for the region (G. pseudosyriacus) and two are new species (G. lordeganensis and G. bakhteyaricus). From the taxonomic point of view, head microsculpturing characters were found to be reliable as discriminating sets of characters useful in species identification. Habitat diversification and climatic fluctuations appear to be the main factors for species diversity of the area, and the Zagros Mountains act as a geographical barrier to species distribution.     

Survival and reproduction of the mussel Xenostrobus securis (Lamarck) (Mollusca; Bivalvia; Mytilidae) in a Western Australian estuary. Pt. II: Reproduction,growth and longevity

Summary

Growth, longevity and breeding characteristics of populations of the mussel Xenostrobus securis in the Swan Estuary are remarkably variable, both between one year and another and between upstream and downstream localities. These characteristics and their variability may be accounted for by the species' physiological responses and limitations to variable salinity conditions. The Swan Estuary is subject to extreme temporal and spatial variations in salinity. Temperature has only a secondary significance on the biology of the mussel in this estuary.

Activity including growth is inhibited at chlorinities below 2‰. This occurs each winter during the discharge period. At Crawley (downstream) the discharge period rarely lasts more than a few weeks in mid winter, but at upstream limits of the estuary (e.g. Barker Bridge) it is highly variable and may last as long as seven months. Consequently the period of no-growth which corresponds to the discharge period varies between downstream and upstream populations and the total annual growth increment varies accordingly. Similarly the duration of the no-growth period and the total annual growth increment varies from year to year at upstream localities.

At Crawley mussels live only one year. At that locality there is almost total mortality of adults soon after spawning. The relationship of the post-reproductive mortality to intensity of reproductive effort is discussed. At Barker Bridge heavy post-reproductive mortality was not observed and animals may live two years or more. This greater longevity at Barker Bridge is considered to have survival advantage for the population which is living in an unstable and inconsistent environment. Downstream conditions are more seasonally regular and the populations there can rely on having optimal conditions each year.

Spawning begins at the downstream end of the estuary in November or December when the chlorinity rises to the critical lower limit for larval development (8 to 9‰. Cl). A wave of spawning moves up the estuary as the summer progresses, following the zone of optimal salinity conditions. It does not reach Barker Bridge until February or March. In 1964 the chlorinity did not reach the lower limit for larval development at Barker Bridge and no spawning or spatfall occurred there.

It is considered that X. securis is physiologically well adapted for persistence in an estuarine environment characterized by variable and unstable salinity conditions.     

XII.—The upper Valentian trilobite fauna of Shropshire

Summary

Records of ten species of Sosylus collected in Nigeria are given, with details of distribution, host trees and platypodid associates. The Sosylus fauna of Nigeria appears to lie between that of Ghana and the Congo in species composition. Comment is made on the close association that some Sosylus species have with their platypodid hosts.     

Survival and reproduction of the mussel Xenostrobus securis (Lam.) (Mollusca: Bivalvia: Mytilidae) in a Western Australian estuary

Summary

The Swan estuary is subject to extreme temporal and spatial variations in salinity. Downstream populations of the mussel Xenostrobus securis (Lamarck, 1819) are exposed to a seasonal range from 1·5‰. Cl to 20·0‰. Cl. In summer the estuary is progressively filled with saline water from the sea; in winter it is flooded by fresh river run-off water from the heavy and concentrated winter rains. The autumn fall in salinity is usually very rapid and constitutes a severe physiological shock for organisms inhabiting the estuary.

The physiography and hydrology of the Swan estuary are described. Experiments are reported on the salinity tolerance and behavioural responses to salinity stresses of adult mussels and larval stages.

Adult mussels show no ability to osmoregulate (except possibly at very low salinities). They can tolerate environmental chlorinities at least as high as 31‰. Cl and can withstand sudden dilutions from at least 18‰. down to 1‰.. They are capable of survival at 1‰. for many months.

Closure of the shell valves in response to sudden dilutions of the medium is a behavioural mechanism minimizing physiological shock. Adult mussels remain inactive with the valves closed indefinitely at chlorinities below 2‰.. However, the internal body fluids of the mussels become isotonic with the medium after a few days. Adult salinity tolerance and behavioural responses are sufficient to meet the conditions occurring in the estuary, and adult salinity tolerance is unlikely to limit distribution of the species.

In laboratory dishes eggs may be successfully fertilized, and normal cleavage occurs in water between about 8 to 9‰. and 17·5‰. Cl. This tolerance range of developing larvae imposes upstream limits on the distribution of the mussel and precludes any possibility of larval dispersal between adjacent estuaries by way of the sea.     

The Conidae (Mollusca: Gastropoda) of India

Summary

The polyp and immature medusa stages of Cladonema californicum Hyman, are described. The life cycle of the species was observed in the laboratory and took about 47 days to complete under laboratory conditions. Field collections from Bodega Harbor indicated that the medusae and reproductive polyp are present all year. A review of the taxonomy of the genus reveals that there are possibly only two valid species of Cladonema if one bases species separation on the medusa alone: C. radiatum and its ‘varieties’, and C. californicum. Additional work is needed to elucidate the relationships among the described varieties of the medusae of C. radiatum and the morphology of their respective polyps before further revision of the genus can be attempted.     

L.—Notes on Cecidomyidæ

Resumé

This paper is mostly concerned with records of mites new to the British Isles. Odd notes on the biology of some species previously recorded from these islands deal with various aspects of the general biology of the different species. The following species are described as new to science:—Parasitus hibernicus, Phaulodiaspis euris, Ettmulleria dipterorum, and Schwiebea boletophagi. The newly discovered male of Polyaspinus cylindricus Berl. is described fro the first time and its importance in the study of the comparative parative morphology of the Mesostigmata is discussed. The division of the genus Pergamasus by Hull in 1918 is treated in some detail and his subgenera, Plesiogamasus, Paragamasus are promoted to generic status. Some remarks are made on the generic divisions of the Hypoaspis complex of the Laelaptidae and two new genera of Dr. Hull, Chamolaelaps and Halbertia, are brought forward and the types of all the above genera of Dr. Hull designated. New records of Leptus porcinus Hull, 1918 are given and the species is figured in detail.     

Coexistence of species of two amphipod genera: Niphargus timavi (Niphargidae) and Gammarus fossarum (Gammaridae)

The co‐occurrence of amphipods Niphargus timavi and Gammarus fossarum was studied. A small brook in SW Slovenia was sampled monthly for one year. Below the primary spring the brook sinks, flows for about 150 m below the surface and springs again. Gammarus fossarum never reached the stretch above the sink. Both species were found at all sampling sites below the secondary spring throughout the year, but the abundance of the two varied along the stream spatially and temporarily. Differences in life cycles between G. fossarum and N. timavi were not informative; however, the estimated reproductive potential of G. fossarum was much higher than of N. timavi. A result of the higher reproductive potential may be the dominance of gammarids in permanent waters, while N. timavi may invade a surrounding fissure system where it survives gammarid competition and summer desiccations when the gammarid population becomes extinct.     

A new species of Metatrichoniscoides (Crustacea: Isopoda: Oniscoidea) from the coast of South Wales,U.K.

Summary

A new species of terrestrial isopod, Metatrichonixoides celticus is described and differentiated from other European species of the same genus. M. celticus occurs on the coast of South Wales, U.K. and its supralittoral habitat is outlined.     

A re-assessment of the genera Holorusia Loew (=Ctenacroscelis Enderlein), Ischnotoma Skuse and Zelandotipula Alexander (Diptera: Tipulidae), with notes on their phylogeny and zoogeography

Summary

A short historical background to the genera considered is given. A review is made of a number of characters which had previously only been treated inconsistently, or not at all. As a result, the old-world genus Ctenacroscelis is merged with Holorusia sensu stricto, as represented by the isolated Californian type-species. All other species previously referred to Holorusia sensu lato are redistributed to two genera; the tropical South American and New Zealand forms are united into Zelandotipula; the Chilean element and the Australian species are united into Ischnotoma, the name Icriomastax Enderlein being resurrected as a subgenus to receive most of the Chilean species.

Tentative phylogenetic and zoogeographic observations are made. Holorusia and Ischnotoma are considered and discussed as sister-groups, whilst Zelandotipula is believed to be only distantly related. Zoogeographically Holorusia is seen as a successful Asiatic genus; Ischnotoma as a receding group, with extreme southern-continental distribution, having had a much wider distribution as indicated by the European Oligocene fossil Holorusia vasifera, transferred here to Ischnotoma. Zelandotipula is viewed as an essentially Neotropical genus, which has made one ‘invasion’ of New Zealand, probably in the geologically recent past.

Résumés of the principal features of the re-defined genera are given, together with systematic notes on certain species, and species catalogues giving distributions and all new name combinations.     

The carboniferous fossil lycopod Ulodendron landsburgii (Kidston) comb. nov.

Summary

A data gathering system controlled by microcomputer, recording swimming activity, is described. Prior to the breeding season, in a normal day and night regime, the delta prawn Palaemon longirostris shows a circadian swimming rhythm with peak activity at night. As the ovaries ripen and the prawns mate there is evidence of an additional tidal swimming rhythm. Females carrying eggs revert to nocturnal circadian swimming only. In ovigerous females the circadian swimming rhythm persists in continuous darkness with a free-running period of between 22 and 23 hours. The closely related and sympatric species Palaemonetes varians has similar patterns of swimming behaviour. It is suggested that the absence of newly hatched palaemonid larvae in the estuary is a result of the interaction of these adult swimming patterns with tidal flow and nocturnal hatching.     

The Mollissima subgroup of fannia Desvoidy,with the description of a new species from Burma and a revised key to species (Diptera: Muscidae)

Synopsis

A comparison of the type-species of the genus Coelomyia Haliday (C. mollissima Haliday) with that of the genus Fannia Desvoidy (F. scalaris Fabricius) shows that these two genera cannot be maintained as equivalent phylogenetie taxa. Coelomyia is synonymized with Fannia and its species placed in Fannia, four new combinations thus being established. The mollissima subgroup is defined and its affinities shown, a new species is described, and a revised key to species is given.     

Breeding preferences in the treefrogs Dryophytes japonicus (Hylidae) in Mongolia

ABSTRACT

When a species occurs over a broad range of climates and landscapes, the breeding ecology of that species is expected to vary locally. Additionally, a basic knowledge of breeding ecology is required before other types of studies may be conducted, such as physiology or conservation. In North East Asia, Dryophytes japonicus is distributed from Japan to Mongolia, where its breeding ecology is unknown. The objectives of this study were to understand the breeding requirements of D. japonicus in this part of its range. We collected data for Dryophytes japonicus at 56 sites located within 23 independent localities in Northern Mongolia during the breeding season 2017. The data collected included habitat type and co-occurring amphibian, fishes and bird species. Our results show that the species prefers circa 70 m long oxbow lakes for breeding, while habitat characteristics, water quality and co-occurring species were not significantly associated with the occurrence of the species. We therefore conclude that D. japonicus is behaviourally plastic in Mongolia, as it is in other portions of its range, and that the species can use several types of environments and co-occur with different species at its breeding sites. Corvus dauuricus was the only bird species significant predicting the occurrence of D. japonicus, likely because of overlapping ecological preferences.