Exotic oniscideans (Crustacea: Isopoda) in coastal salt marshes: first record of the families Halophilosciidae and Platyarthridae in Continental Chile

We report two new exotic introduced isopods in Chile: Halophiloscia couchii of the family Halophilosciidae and Niambia capensis of the family Platyarthridae. This report provides first evidence of the presence of these species in the Southeastern Pacific. These species were found in several salt marshes and beaches spanning nearly 2000?km of the Chilean coast. With the data reported here, the percentage of exotic oniscidean isopods in Chile is 28%.     

Parasitism by isopods in sandy beach fish assemblages: role of urbanization and environmental characteristics

Parasitism by isopods is a common phenomenon in marine fishes and may induce negative effects, especially in juvenile stages. The surf-zones of sandy beaches are an important nursery habitat for many fish species, including commercially important ones, and are structured by beach characteristics and human activities, which are suggested to influence the fishes’ susceptibility to parasitism. Here, we analyze the early infestation and prevalence of parasitism in surf zones fishes of 27 beaches in southeastern Brazil with different characteristics. Parasites were recorded in only seven of the beaches. A high infestation was found in a single site, the highly urbanized Itaguá beach, where the prevalence of parasitism on juveniles and early adults of the Atlantic anchoveta Cetengraulis edentulus was high (68.11%). Four species of parasitic isopods were found, all belonging to the Cymothoidae family, but Livoneca desterroensis was the most abundant (78.7%). No effects of parasitism were detected on the size, weight and physiological condition of fishes, but presence of parasites and prevalence of infestation were positively affected by urbanization. Overall, our results indicate that the surf-zones have low parasite infestation, yet, they suggest that anthropic effects such as urbanization may enhance the prevalence of isopod parasitism.

     

A study of the endogenous activity rhythms of the marine isopod Exosphaeroma truncatitelson

The endogenous activity rhythms of the South African endemic isopod Exosphaeroma truncatitelson were explored. Isopods were collected on days coinciding with either a neap or spring tide. High- and low-energy beaches, which vary in the intensity of wave action, were selected as study sites. Isopods, in groups of 10–30, were placed in glass tanks with different experimental conditions: darkness + no sand, darkness with sand and natural ambient light (no sand). Activity of the isopods was measured for 50 h by recording the number of isopods swimming actively during a 30-s period. These isopods exhibited an endogenous activity rhythm which coincided with the tidal cycle even though removed from their natural habitat. Cosine curves were fitted to the observed activity data and statistical differences across variables were investigated. Peak activity was shown to occur shortly after high tide. Similar activity cycles were observed for both neap and spring tides and for different times of the year. Results also indicated that the activity cycles at both low- and high-energy beaches were similar. Two survival advantages of this rhythm are proposed: prevention of stranding on high shores and competitive avoidance with other local isopod species.     

广东硇洲岛的瓣鳃类

根据1999－2001年在广东硇洲岛海滨的岩石岩,砾石滩,泥沙滩,泥沙滩,沙滩,红树林区潮间带和近海区潮下带等各种生态环境采集到的瓣鳃类动物的整理鉴定,获得瓣鳃炎77种,分隶于24科44属,本文对其区系组成及分布特点进行了详细的论述。     

Distribution, habitat selection and colony types of the Amsterdam Island fur seal Arctocephalus tropicalis at Gough Island

The present study was undertaken during the summers of 1974/75 and 1975/76. Beaches were classified according to their topography and structure, and colony types were classified according to age and sex composition during the breeding season peak haul-out. Breeding success was measured by the total number of pups born. All available beaches were occupied during the breeding season, breeders predominating on the windward west coast and nonbreeders on the leeward east coast. Principal factors influencing the distribution of breeding fur seals were the topography and physical nature of the beaches, ambient temperatures and solar radiation, sea condition, and exposure to wind and sea spray. The resultant distribution pattern is ascribed to a behavioural thermoregulatory response in A. tropicalis so as to reduce exogenous heat-loading during the summer breeding season.     

Isopódos litorales de la Costa de concepción,Chile central

Littoral isopods of the coast of Concepción, Central Chile

A collection of isopods is studied from the intertidal region of the province of Concepción (Chile), located on the South American pacifics coast between 36 and 37° S latitude.

The collection consists of 11 species, two of them new for science: Ianiropsis kussakini, described here, and Janira sp., still under study. The distribution of species is, grosso modo, restricted to the central zone or south center of Chile, which seems to corroborate the opinion of some authors who consider it as a region of biogeographic transition between the Peruvian and Magellan provinces.     

The primary production of phytoplankton in the restored Maltañski Reservoir in Poland

Patterns in composition, abundance and diversity of the annelid fauna (Polychaeta and Oligochaeta) in 22 sandy beaches in Iceland were explored. The effect of exposure on annelid distribution was studied. A total of 5651 annelids were recorded from 160 core samples. Oligochaetes (chiefly Tubificidae) dominated the annelid assemblage whereas polychaetes represented a minor fraction. Polychaetes were relatively more abundant in exposed than in sheltered beaches, contrary to oligochaetes. Meiofaunal polychaete species were also more abundant in exposed than in sheltered beaches. Southwest beaches seemed more diverse in annelid species than northern ones. Annelid diversity did not differ between sheltered and exposed sites, but higher diversity was attained in fine sands at sheltered areas. Cluster analysis revealed large differences between beaches in the annelid community composition. The general patterns found suggest that beach exposure is a major factor conditioning macro- and meiofaunal polychaete and oligochaete distribution along the Icelandic coast.     

Global Diversification at the Harsh Sea-Land Interface: Mitochondrial Phylogeny of the Supralittoral Isopod Genus Tylos (Tylidae,Oniscidea)

The supralittoral environment, at the transition between sea and land, is characterized by harsh conditions for life. Nonetheless, evolution of terrestrial isopods (Oniscidea), the only group of Crustacea fully adapted to live on land, appears to have involved a transitional step within the supralittoral. The two most basal oniscidean lineages (Ligiidae and Tylidae) have representatives that successfully colonized the supralittoral. One of them is the genus Tylos, which is found exclusively in supralittoral sandy beaches from tropical and subtropical coasts around the world. Comprehensive phylogenetic hypotheses for this genus are lacking, which are necessary for understanding the evolution and biogeography of a lineage that successfully diversified in the harsh sea-land interface. Herein, we studied the phylogenetic relationships among 17 of the 21 currently recognized species of the genus Tylos, based on sequences from four mitochondrial genes (Cytochrome Oxidase I, Cytochrome b, 16S rDNA, and 12S rDNA). Maximum Likelihood and Bayesian phylogenetic analyses identified several lineages with deep divergences and discrete geographic distributions. Phylogenetic and distributional patterns of Tylos provide important clues on the biogeography and evolution of this group. Large divergences among the most basal clades are consistent with ancient splits. Due to the biological characteristics of Tylos, which likely prevent dispersal of these isopods across vast oceanic scales, we argue that tectonic events rather than trans-oceanic dispersal explain the distribution of Tylos in different continents. Overwater dispersal, however, likely enabled range expansions within some basins, and explains the colonization of volcanic oceanic islands. Present-day distributions were also likely influenced by sea level and climate changes. High levels of allopatric cryptic genetic differentiation are observed in different regions of the world, implying that the dispersal abilities of Tylos isopods are more limited than previously thought. Our results indicate that a taxonomic revision of this group is necessary.     

Did global warming and alien invasions affect surf zone hyperbenthic communities on sandy beaches in Belgium?

Due to global warming, southern hyperbenthic species were expected, which extend their distribution range northwards. It was also expected that alien species would have invaded the surf zone hyperbenthos. Therefore, the species composition of the hyperbenthos occurring along the Belgian coast was determined, and spatial and temporal patterns in community composition were assessed. The hyperbenthos was sampled with a hand-pushed sledge on 10 sandy beaches during summer 1995, winter 1996, summer 2009 and winter 2010. Neither alien species nor any southern species which recently extended its distribution range northwards were observed during the present study, indicating that alien species and global warming did not yet affect the species composition of the surf zone hyperbenthos along the Belgian coast. The hyperbenthic community was dominated by Mysida, while Amphipoda were the most diverse group. Multivariate analysis revealed that temporal patterns dominated over spatial patterns: winter and summer hyperbenthic communities clearly differed in species composition and different species assemblages were also observed between the first and the recent sampling campaigns. Although for several other groups, a decline in species richness has been observed closer to the mouth of the Westerschelde, no spatial gradient could be recognised for the surf zone hyperbenthos. Instead, it was found that species richness was positively related to beach width. It could be concluded that the species composition and the total abundance of surf zone hyperbenthic communities along sandy beaches of the Belgian coast strongly vary in space, but especially in time.     

Taxonomy,natural history and zoogeography of sand beach isopods from the coast of Southern Chile

Seven species of marine isopods were collected on sandy beaches of Southern Chile (from about 37° S until 42° S). From these, Excirolana hirsuticauda Menzies, Excirolana monodi Carvacho, Chaetilia paucidens Menzies, Macrochiridothea setifer Menzies and M. mehuinensis Jaramillo are known only from the Chilean coasts. Another species, Excirolana braziliensis Richardson, is known from other areas of American coasts. One species is identified here as Macrochiridothea aff. lilianae by its resemblance with M. lilianae Moreira from Southern Brazil. All these species are here briefly described and some aspects of their ecology added. Also Zoogeographic characterization of the studied area is discussed in relation to the distributional patterns of isopods living in them.     

Environmental limits to the distribution of Scaevola plumieri along the South African coast

Abstract. Scaevola plumieri is an important pioneer on many tropical and subtropical sand dunes, forming a large perennial subterranean plant with only the tips of the branches emerging above accreting sand. In South Africa it is the dominant pioneer on sandy beaches along the east coast, less abundant on the south coast and absent from the southwest and west coasts. Transpiration rates (E) of S. plumieri are predictably related to atmospheric vapour pressure deficit under a wide range of conditions and can therefore be predicted from measurement of ambient temperature and relative humidity. Scaling measurements of E at the leaf level to the canopy level has been demonstrated previously. Using a geographic information system, digital maps of regional climatic variables were used to calculate digital maps of potential transpiration from mean monthly temperature and relative humidity values, effectively scaling canopy level transpiration rates to a regional level. Monthly potential transpiration was subtracted from the monthly median rainfall to produce a map of mean monthly water balance. Seasonal growth was correlated with seasonal water balance. Localities along the coast with water deficits in summer corresponded with the recorded absence of S. plumieri, which grows and reproduces most actively in the summer months. This suggests that reduced water availability during the summer growth period limits the distribution of S. plumieri along the southwest coast, where water deficits develop in summer. Temperature is also important in limiting the distribution of S. plumieri on the southwest coast of South Africa through its effects on the growth and phenology of the plant.     

Distribution and abundance of meiofauna in intertidal sand substrata around Iceland

Iceland is situated in an important subarctic transition area where complex oceanographic dynamics occur. The intertidal, subtidal, and deep-sea faunal communities of Iceland are being intensively studied, as a critical resource for continued sustainability of fisheries and the preservation of northern littoral ecosystems. However, the meiofaunal communities and the environmental factors affecting them are still relatively poorly known. The meiobenthic metazoan community was studied with core sampling in 23 sandy beaches along the intertidal zone of the Iceland coast in a campaign developed in September 2003. Small-scale variation in meiofauna composition (major taxa) was explored and related to biotic and abiotic factors at different scales, such as beach exposure, granulometry, and organic matter content. Differences in meiofaunal community structure at a low taxonomic resolution appeared among beaches located within wide biogeographical zones of hydrobiological significance (NE and SW Shelf regions) and exposure degrees. Seventeen major taxa were recorded. In contrast with more local and taxon-focused studies, oligochaetes were the dominant group all around Iceland, followed by nematodes, turbellarians, gastrotrichs, and copepods (mainly harpacticoids). Acari, ascidians, bivalves, cnidarians, collembolans, gastropods, isopods, kinorhynchs, insects, nemerteans, ostracods, and polychaetes were relatively scarce groups, together being less than 1.6% of the meiofauna. There was a large variation in meiofaunal abundance between sites. Maximum abundances (>500 ind. cm^?2) were found in Sau?arkrökur, Hraunhafnartangi, and Skálaness, whereas minimum abundances (<40 ind. cm^?2) were recorded in Magnavík, Jokülsárlón (glacier beach site), Vikurnúpur, Breidalsvík, and Stokknes. We did not find a clear pattern in overall meiofaunal abundance regarding the degree of exposure of beaches. Oligochaetes, nematodes, and copepods were relatively more abundant in sheltered beaches, whereas turbellarians and gastrotrichs tended to be more abundant in exposed beaches. The best correlates of meiofaunal composition and abundance within beaches were the proportion of gravels and the content of utilizable organic matter in the sediment. We should consider factors operating at wider scales (importantly beach exposure and overall situation in the complex oceanographical context of Iceland) to find a pattern in the local structure of intertidal meiofaunal assemblages.     

Arrival times,laying dates,and reproductive success of Snowy Plovers in two habitats in coastal northern California

ABSTRACT Habitat quality, as indexed by the reproductive success of individuals, can greatly influence population growth, especially for rare species near the limits of their range. Along the Pacific coast, the Snowy Plover (Charadrius alexandrinus nivosus) is a threatened species that, in recent years, has been breeding on both riverine gravel bars and ocean beaches in northern California. From 2001 to 2009, we compared the habitat characteristics, breeding phenology, reproductive success, and abundance of Western Snowy Plovers occupying these two habitats. Similar percentages of yearling and adult plovers returned to gravel bars and beaches, but plovers breeding on gravel bars arrived and initiated first clutches 2–3 weeks later than those breeding on beaches. Despite this delay, however, the mean annual fledging success of plovers on gravel bars (1.4 ± 0.4 [SD]) was double that on beaches (0.7 ± 0.3). Differences in cumulative reproductive success produced a stronger pattern. By their sixth year, males on gravel bars had fledged 14.5 ± 2.1 chicks, more than four times the number of young fledged by males on beaches (3.3 ± 3.1). Over 9 years, local population size decreased by about 75%, coincident with a shift in breeding distribution away from high‐quality gravel bars to ocean beaches. This unexpected population decline and shift to poorer quality beaches may have been related to occasional low survival of plovers that over‐winter exclusively on beaches in our study area. Consistently low productivity of plovers breeding on ocean beaches suggests the need for intensified management to ameliorate the negative impacts of predation and human activity on the recovery of this population.     

Foraging activity of the sand beach isopod Scyphax ornatus Dana

Abstract

The terrestrial isopod Scyphax ornatus lives on exposed sand beaches. Adult isopods spent the daytime in burrows near the high water mark and made nightly foraging excursions over the uncovered middle beach. Hourly records of their night time distribution showed that Scyphax congregated near the water’s edge during the last 4 h of flood tide, where they fed on carrion. Insects (mostly drowned honey bees) were the main food item, but coelenterates, amphipods, crabs, and goose barnacles were also eaten. During ebb and early flood tides Scyphax occurred at low densities over the uncovered middle beach. Analysis of the distribution of large and small food items on the beach showed that by feeding during the flood tide, Scyphax exploited a rich concentration of carrion that accumulated in the swash zone and that was moved slowly up the beach by the incoming tide.     

Exploring macroinvertebrate species distributions at regional and local scales across a sandy beach geographic continuum

Exposed sandy beaches are highly dynamic ecosystems where macroinvertebrate species cope with extremely variable environmental conditions. The majority of the beach ecology studies present exposed beaches as physically dominated ecosystems where abiotic factors largely determine the structure and distribution of macrobenthic communities. However, beach species patterns at different scales can be modified by the interaction between different environmental variables, including biotic interactions. In this study, we examined the role of different environmental variables for describing the regional and local scale distributions of common macrobenthic species across 39 beaches along the North coast of Spain. The analyses were carried out using boosted regression trees, a relatively new technique from the field of machine learning. Our study showed that the macroinvertebrate community on exposed beaches is not structured by a single physical factor, but instead by a complex set of drivers including the biotic compound. Thus, at a regional scale the macrobenthic community, in terms of number of species and abundance, was mainly explained by surrogates of food availability, such as chlorophyll a. The results also revealed that the local scale is a feasible way to construct general predictive species-environmental models, since relationships derived from different beaches showed similar responses for most of the species. However, additional information on aspects of beach species distribution can be obtained with large scale models. This study showed that species-environmental models should be validated against changes in spatial extent, and also illustrates the utility of BRTs as a powerful analysis tool for ecology data insight.     

Burrowing abilities and swash behavior of three crabs, Emerita analoga Stimpson, Blepharipoda occidentalis Randall, and Lepidopa californica Efford (Anomura, Hippoidea), of exposed sandy beaches

To investigate factors related to the distribution of intertidal species, and specific predictions of the swash exclusion hypothesis for exposed sandy beaches, we compared the burrowing abilities and swash behavior of three species of anomuran crabs in the superfamily Hippoidea (Emerita analoga, Blepharipoda occidentalis and Lepidopa californica) which commonly inhabit the intertidal and shallow subtidal zones of beaches along the California coast. Burrowing times in the laboratory increased significantly with crab size for all species in five sediment grain sizes ranging from fine sand to gravel (0.15 to 3.24 mm). For each species, burrowing times differed significantly among sand grain sizes, ranging from 0.3 to 21.5 s. Burrowing times for the hippid crab, E. analoga, were relatively constant across sediment types, while those of the albuneid crabs, B. occidentalis and L. californica, were rapid in fine to medium sands, and much slower in coarser sediments. Our results indicate that E. analoga is a substrate generalist while L. californica and B. occidentalis are substrate sensitive. Pre-burrowing times and behavior, distance moved, and burrowing times differed among the species in the swash zone. Combined times of preburrowing and burrowing were shorter than the swash period (6 s) for most E. analoga individuals. Fifty percent of the individuals of L. californica reached the substrate and burrowed in the swash period, while no individuals of B. occidentalis burrowed in that time. Pre-burrowing behavior and time may be valuable in explaining spatial and temporal patterns in the distribution of hippoid crabs on California beaches. Our results support predictions of the swash exclusion hypothesis concerning the burrowing and locomotory abilities of sandy beach macrofauna. The substrate generalist characteristics, and unique orientation and swimming abilities of the hippid crab, E. analoga, in intertidal swash may help explain the success of this species and its congeners, and have important implications for understanding patterns of macrofauna community structure on exposed sandy beaches in California and other regions.     

Investigations into the biology of the garfish, Belone belone (L.), in Swedish waters

Garfish, Belone belone (L.), were collected from commercial fishermen between May and September of 1987 from around the Swedish coast. Fish belonging to the year classes of 1983, 1984 and 1985 dominated the catch, with very few fish from the year classes of 1980, 1981 and 1982. Maturity stages and condition were investigated, and estimates of fecundity calculated; these ranged from 2193 to 10804 eggs per ripe female. Examination of gut contents showed fish, especially juvenile clupeids and gasterosteids, as well as isopods and amphipods, to be the most important components of their diet. Garfish populations from both the Baltic and the west coasts were parasitized by copepods of the genus Caligus . A study of meristic characteristics showed a significant difference between the number of vertebrae in fish from the Baltic and those captured on the west coast of Sweden.     

Spatial variation in population dynamics of the sand-burrowing amphipod Haustorioides japonicus

Densities of sandy beach organisms along coastlines often vary considerably even within small local scales. In order to understand the demographic basis of density variations in shore animals, we examined the population dynamics of the amphipod Haustorioides japonicus Kamihira, which is an ideal subject because it lacks a planktonic dispersal stage in its life history. Quantitative sampling at three adjacent sandy beaches along the Sea of Japan coast revealed that the spring density, i.e., the density of overwintered individuals, was similar among the three beaches. However, the amount of recruitment of newly hatched juveniles from late spring to summer greatly differed among the beaches, resulting in large spatial variations in the summer density. Cohort analyses revealed that at all beaches, young-of-the-year (YOY) individuals reproduced and then died, and that individuals which recruited in late summer overwintered. Moreover, growth, fecundity, and survival schedules of overwintered and YOY individuals were very similar among beaches. These observations suggest that the difference in recruitment success, i.e., the survival of newly hatched juveniles, is the primary cause of the inter-population variation in the summer density. It is likely that variations in salinity and sandy sediment affect the recruitment success of newly hatched individuals. This study indicates that biological productivity may differ substantially even among adjacent sandy beaches, with important implications for beach management.