Summer Abundance Research Articles

Viral lysis and nanoflagellate grazing as factors controlling diel variations of Synechococcus spp. summer abundance in coastal waters of Taiwan

Diel variations in the protozoan grazing and viral-mediated mortality of Synechococ- cus spp. were simultaneously estimated using a modified dilution method in the coastal waters off Taiwan during 4 cruises in summer 2011. During the study period, the abundance of Synechococ- cus spp. showed a clear diel cycle and ranged from 1.2 × 10 4 cells ml �1 at 08:00 h to 9.8 × 10 4 cells ml �1 at midnight. The frequency of dividing cell (FDC) values were highest between afternoon and dusk and decreased to <10% between 20:00 and 08:00 h. Synechococcus spp. specific growth rates varied during the experimental period from 0.025 to 0.033 h �1 and 0.050 to 0.085 h �1 at day- time and nighttime, respectively. Rates of Synechococcus spp. mortality due to nanoflagellate grazing averaged 0.031 h �1 during daytime and 0.041 h �1 at night. The estimated mortality due to viral lysis was between 0.011 and 0.019 h �1 during daytime and between 0.026 and 0.065 h �1 at night. Nanoflagellate grazing was the dominant cause of Synechococcus spp. mortality during daytime; however, mortality from viral lysis and nanoflagellate grazing was more balanced at night.

Seasonal fatty acid profile analysis to trace origin of food sources of four commercially important bivalves

Knowledge of bivalve food sources has great importance in aquaculture areas where cultured species usually occur at higher densities than in natural populations. Except phytoplankton, which is considered as their primary food sources, bivalves can use other food sources such as detritus, bacteria and zooplankton. The objective of this study was to determine food sources of four commercially important bivalve species co-existing in the Mali Ston Bay — most important aquaculture area of the eastern Adriatic Sea. Food sources were investigated by analyzing the fatty acid profiles of digestive gland and muscle tissues of the European flat oyster Ostrea edulis and the black mussel Mytilus galloprovincialis, cultured in the water column, and the bearded horse mussel Modiolus barbatus and Noah's ark shell Arca noae from natural populations. Digestive gland fatty acid analysis revealed that during the period of higher plankton abundance in spring and summer, all species ingested mainly phytoplankton followed by zooplankton and detritus. During the low plankton abundance of the autumn–winter period zooplankton and/or detritus became more important in a bivalve diet. Fatty acid composition of muscles indicated differences in selective incorporation of polyunsaturated fatty acid (PUFA) from their diets. While A. noae and M. barbatus accumulated significantly PUFAs during all and O. edulis during spring–summer period, in M. galloprovincialis this tendency was not observed at all. This suggested better utilization of ingested food in bottom-dwelling species. Because all four species consumed similar food sources they were in competition. However, as investigated species in Mali Ston Bay exist in high density, primary production plus the availability of other food sources in this area was probably sufficient to satisfy demands for all species. Aquaculture in the study area depends wholly on natural spat. This suggests that larviphagy, observed for all species, might constitute a self-regulating restriction to natural populations and/or commercial aquaculture growth.

Ten-year variations in population structure of pink-shrimp in a southwestern Atlantic Bay affected by highway construction

OBJECTIVES: Population structures of Farfantepenaeus brasiliensis and F. paulensis, consisting mainly of juveniles, were evaluated during the construction of an expressway along a mangrove area. Estuarine regions in southern Brazil function as sites for reproduction, nursery and growth of a variety of organisms, including two of the most important species of shrimp for fisheries in the southwestern Atlantic. Shrimps were collected in Saco dos Limões creek, Baía-Sul, Florianópolis, State of Santa Catarina, four times a year, by day and night, between 1997 and 2006. Fluctuations in the abundances of shrimp appear to be related to their life cycles, with largest abundances in Summer and Spring, rather than to impacts promoted by dredging activities during the expressway construction.

Fish assemblages of interior tidal marsh channels in relation to environmental variables in the upper San Francisco Estuary

Tidal marsh wetlands represent critical habitat for many estuarine fishes and are particularly important to conserving and restoring native and at-risk species. We describe the seasonal and regional variation in the composition and abundance of fishes in interior tidal marsh channels in the upper San Francisco Estuary (SFE), and relate these to variation in environmental conditions. Fish were sampled quarterly using modified fyke nets from October 2003 to June 2005 in 18 interior tidal marsh channels spanning 3 distinct river systems: Petaluma River, Napa River and West Delta. We collected 116 samples and 9452 individuals of 30 fish species. Four non-native species dominated—Mississippi silverside, western mosquitofish, yellowfin goby, and rainwater killifish—with an additional 13 species occurring commonly (represented equally by natives and non-natives, residents and transients). Large seasonal differences in composition and abundance of fishes occurred, with the lowest abundances in winter and spring and highest abundances in summer and fall. Correlation of ordination scores and environmental variables further supported the importance of season, as well as fish species’ status (native vs. non-native), feeding preference (pelagic vs. demersal), and marsh utilization (resident vs. transient), as factors influencing fish assemblage composition. The proximity of the marsh systems to freshwater and marine influences, which largely control salinity and temperature variation, explained 26% of the variation in fish composition, while channel geomorphology explained 22%. We recommend that both edge habitat (which may be beneficial to fish foraging success) and the extent of tidal connectivity (which allows access for fishes), in addition to location along the estuarine gradient, be considered in designing and managing tidal marsh restoration.

Blooms of toxin-producing Cyanobacteria — a real threat in small dam reservoirs at the beginning of their operation

Abstract Large and harmful cyanobacterial blooms appeared in two newly-built artificial reservoirs shortly after being filled with water. Taxonomic composition of cyanobacterial communities was highly variable in both water bodies and fast species replacement was observed. In the first year of the operation of the smaller Konstantynów Reservoir, the mass development of Anabaena flos-aquae and Planktolyngbya limnetica (48.7 and 53.6% of the cyanobacterial abundance) occurred in summer, while in autumn the dominance of Planktothrix agardhii (99.9%, 14.95 × 106 ind. Dm−3) was noted. The surface scum developed in summer consisted of An. flos-aquae that contained high amounts of anatoxin-a (1412.4 μg AN-a dm−3 of scum) and smaller amounts of microcystins (10 μg eq. MC-LR dm−3 of scum). In the larger Kraśnik Reservoir, Aphanizomenon flos-aquae occurred in high abundance in spring and summer, however, it was replaced by different species of Microcystis (1.3 × 107 ind. dm−3) which created thick surface scum. Simultaneously, a hazardous increase in the total concentration of microcystins (from 13.6 to 788.5 μg eq. MC-LR dm−3 of water with scum) and anatoxin-a (from 0.03 to 43.6 μg dm−3) was observed.

Molecular Enumeration of an Ecologically Important Cyanophage in a Laurentian Great Lake

Considerable research has shown that cyanobacteria and the viruses that infect them (cyanophage) are pervasive and diverse in global lake populations. Few studies have seasonally analyzed freshwater systems, and little is known about the bacterial and viral communities that coexist during the harsh winters of the Laurentian Great Lakes. Here, we employed quantitative PCR to estimate the abundance of cyanomyoviruses in this system, using the portal vertex g20 gene as a proxy for cyanophage abundance and to determine the potential ecological relevance of these viruses. Cyanomyoviruses were abundant in both the summer and the winter observations, with up to 3.1 × 10(6) copies of g20 genes ml(-1) found at several stations and depths in both seasons, representing up to 4.6% of the total virus community. Lake Erie was productive during both our observations, with high chlorophyll a concentrations in the summer (up to 10.3 μg liter(-1)) and winter (up to 5.2 μg liter(-1)). Both bacterial and viral abundances were significantly higher during the summer than during the winter (P < 0.05). Summer bacterial abundances ranged from 3.3 × 10(6) to 1.6 × 10(7) ml(-1) while winter abundances ranged between ∼3.4 × 10(5) and 1.2 × 10(6) ml(-1). Total virus abundances were high during both months, with summer abundances significantly higher at most stations, ranging from 6.5 × 10(7) to 8.8 × 10(7) ml(-1), and with winter abundances ranging from 3.4 × 10(7) to 6.6 × 10(7) ml(-1). This work confirms that putative cyanomyoviruses are ubiquitous in both summer and winter months in this large freshwater lake system and that they are an abundant component of the virioplankton group.

The role of phytoplankton in the modulation of dissolved and oyster cadmium concentrations in Deep Bay, British Columbia, Canada

We previously identified dissolved cadmium (Cd diss) as the main source of this metal in cultured Pacific oysters, Crassostrea gigas, in Deep Bay, British Columbia, Canada (Lekhi et al., 2008). Total suspended particulate Cd (Cd part) was not found to be a significant source of oyster Cd (Cd oys), with Cd part > 20 μm negatively correlated with Cd oys concentration. High phytoplankton abundance in spring and summer was hypothesized to reduce Cd oys indirectly by drawing down Cd diss and increasing oyster growth. In the present study we expanded on these results by examining specifically how the phytoplankton community composition modulates both Cd diss and Cd oys concentrations in Deep Bay. Based on calculations of nutrients and Cd diss drawdown, phytoplankton accounted for approximately 90% of the overall summer reduction in Cd diss in the bay. Diatoms were the dominant phytoplankton group, being correlated negatively with Cd oys and positively with Cd part. This suggests that diatom growth mediates the transfer of Cd from the dissolved to the particulate phase, resulting in lower Cd oys. Spring blooms and sporadic harmful algal blooms may mediate a large flux of Cd part to the sediments. Thus, phytoplankton act as a sink, rather than a source, of Cd to oysters in Deep Bay and have a crucial role in the seasonality of Cd oys by reducing the concentration of Cd diss during the summer. Based on environmental variables, two descriptive models for annual Cd oys concentrations were developed using multiple linear regression. The first model (R 2 = 0.870) was created to explain the maximum variability in Cd oys concentrations throughout the year, while the second (R 2 = 0.806) was based on parameters that could be measured easily under farm conditions. Oyster age heavily affected both models, with the first model being secondarily affected by temperature and the second one being more sensitive to changes in salinity.

Monitoring Winter and Summer Abundance of Cetaceans in the Pelagos Sanctuary (Northwestern Mediterranean Sea) Through Aerial Surveys

Systematic long-term monitoring of abundance is essential to inform conservation measures and evaluate their effectiveness. To instigate such work in the Pelagos Sanctuary in the Mediterranean, two aerial surveys were conducted in winter and summer 2009. A total of 467 (131 in winter, 336 in summer) sightings of 7 species was made. Sample sizes were sufficient to estimate abundance of fin whales in summer (148; 95% CI = 87–254) and striped dolphins in winter (19,462; 95% CI = 12 939–29 273) and in summer (38 488; 95% CI = 27 447–53 968). Numbers of animals within the Sanctuary are significantly higher in summer, when human activities and thus potential population level impacts are highest. Comparisons with data from past shipboard surveys suggest an appreciable decrease in fin whales within the Sanctuary area and an appreciable increase in striped dolphins. Aerial surveys proved to be more efficient than ship surveys, allowing more robust estimates, with smaller CIs and CVs. These results provide essential baseline data for this marine protected area and continued regular surveys will allow the effectiveness of the MPA in terms of cetacean conservation to be evaluated and inform future management measures. The collected data may also be crucial in assessing whether ship strikes, one of the main causes of death for fin whales in the Mediterranean, are affecting the Mediterranean population.

Using multitable techniques for assessing the temporal variability of species–environment relationship in a copepod community from a temperate estuarine ecosystem

This study investigated copepod assemblages' distribution patterns and determined the main hydrological and physical factors structuring it at different temporal scales. Copepod and hydrographic surveys were conducted seasonally during a one-year period, at a fixed station in Mondego estuary. Hourly samples were collected, during a diel cycle from sub-surface and 1 m above the bottom, at spring tides. Temporal variability of copepod community was analyzed using the STATICO method. Seasonal variability of the environmental conditions, linked with periods of higher freshwater flow, were the main drivers responsible for copepod community structure observed. Seasonal changes related to environmental factors showed to be strongest in spring and in winter, which accounted with higher species density. Marine and estuarine copepods showed maximal abundance in spring and summer, while the period of higher river flow, coincidently with autumn and winter, imposed changes in the copepods composition, emphasizing the changes in saline zonation within the estuary due to regime of river discharge. STATICO also emphasized the effects of physical forcing at short-term temporal scales. The stable part of the species–environment relationships resulted from the combination of a salinity gradient linked to a fresh, brackish- and marine species gradient, which was dependent on tidal cycle. The STATICO method proved to be a valuable statistical tool to get a clear representation of temporal organization of the copepod assemblages.

Seasonal dynamics and hosts of Amblyomma triste (Acari: Ixodidae) in Argentina

The seasonal dynamics and host usage of Amblyomma triste in Argentina were analyzed. Adults of A. triste were present from early winter to mid-summer, with the peak of abundance from late winter to mid-spring (August to October). Larvae and nymphs were found from December to June, with the peak of abundance in summer. There were no differences among the biological parameters (pre-moult period of larvae and nymphs, pre-oviposition period of females, and minimum incubation period of eggs) of engorged ticks exposed to different photoperiod regimens at the laboratory, but the periods for each biological parameter obtained from ticks exposed in the field were significantly longer than those from the laboratory. Field results fit better with the data of seasonal distribution of each stage. Morphogenetic diapause was not detected, but complementary studies should test the presence of behavioral diapause. Rodents of the subfamily Sigmodontinae (Akodon azarae, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus rufus and Scapteromys aquaticus) are the principal hosts for immature stages of A. triste, the caviid Cavia aperea could be another potential host for these stages, and birds are exceptional hosts for larvae and nymphs. Regarding hosts of adults in Argentina, domestic and wild large-sized mammals belonging to different orders (cattle, dog, horse, Blastocerus dichotomus and Hydrochoerus hydrochaeris) serve as hosts for adults of this tick species. In conclusion, A. triste has a life cycle of 1 year with adults feeding on large endemic and introduced mammals and immature stages using sigmodontine and caviid rodents as hosts.

Seasonal occurrence and biological parameters of the common green lacewing predators of the common pistachio psylla, Agonoscena pistaciae (Hemiptera: Psylloidea)

Species in the carnea complex of the common green lacewing are predators of the common pistachio psylla, Agonoscena pistaciae in both cultivated pistachio plantations and on wild pistachio plants in Iran. The seasonal occurrence of common green lacewings was monitored in pistachio orchards from 2007 to 2008. In addition, the effect of different temperature regimes on prei- maginal development, survival and prey consumption of the predatory lacewing Chrysoperla lucasina fed on A. pistaciae nymphs were studied under controlled conditions. The adults of common green lacewings first appeared on pistachio trees in mid April and were most abundant in early July, decreased in abundance in summer and increased again in October. The relative density of common green lacewings was higher in pistachio orchards where the ground was covered with herbaceous weeds than in those without weeds. In the laboratory females of C. lucasina laid an average of 1085 eggs over 60 days at 22.5°C. The maximum prey consumption occurred at 35°C when the larvae consumed 1812 fourth instar psyllid nymphs during their larval period. The intrinsic rate of natural increase (rm) was 0.11. The total development (egg-adult) required 385 degree-days above the theoretical lower devel- opmental threshold of 9.6°C.

Phytoplankton community changes during wetland restoration in Jinghe Estuary, Lake Ebinur, Xinjiang

精河入湖口湿地是新疆艾比湖湿地的重要组成部分.本文通过空间序列代替时间序列的方法,对艾比湖精河入湖口退化湿地不同恢复期的浮游植物群落特征进行分析,结果表明,恢复早期和中期硅藻种类最多,绿藻在密度上占明显优势,恢复近期硅藻为主要优势类群.恢复早期及自然区浮游植物群落结构较为稳定,中期和近期群落结构不够稳定,易受外界环境的影响.艾比湖精河入湖口退化湿地各恢复时期浮游植物群落结构尚不完善,仍需进一步改善.在季节变化上,浮游植物种类和密度以夏季最多,春季次之,秋季最低;春、秋季以硅藻为主要优势类群,夏季绿藻为主要优势类群,蓝藻在夏季密度高于其它各季节.对各恢复期浮游植物和环境因子进行相关性分析表明,温度、盐度和总磷是影响浮游植物种类和数量的主要因素.;The Jinghe Estuary wetland is one of the main proportions in wetlands of Lake Ebinur, Xinjiang. By using the method of spacial investigation, phytoplankton community was analysed in the wetland of Jinghe Estuary under different restoration stages. The results indicated that in the restoration process, species number of Bacillariophyta was the most diversified in the early and middle stage of the restoration, while Chlorophyta was abundant. Bacillariophyta was dominated in the late stage of the restoration. The structure of phytoplankton community was steady in natural site and in the early stage of restoration, but that was not steady in the middle and late stage of restoration. The species composition and abundance in summer were higher than in spring and autumn. In spring and autumn, Bacillariophyta was the first dominant group in the phytoplankton community. In summer, Chlorophyta became the main dominant group. Cyanophyta in summer had a higher abundance than in spring and autumn. Canonical Correspondence Analysis of phytoplankton and environmental data for all sites showed that temperature, total phosphorus and salinity influenced on the phytoplankton community composition and abundance.

Seasonal occurrence and population structure of the broadnose sevengill shark Notorynchus cepedianus in coastal habitats of south‐east Tasmania

Research longline sampling was conducted seasonally from December 2006 to February 2009 to investigate the occurrence and population structure of the broadnose sevengill shark Notorynchus cepedianus in coastal areas of south-east Tasmania. Notorynchus cepedianus showed a consistent temporal trend in seasonal occurrence in Norfolk Bay characterized by high abundances in summer to near absence in winter. This pattern was less pronounced in the Derwent Estuary, where fish were still caught during winter. The absence of smaller total length (L(T) ) classes (<80 cm) from the catches suggests that N. cepedianus are not using these coastal habitats as nursery areas. Of the 457 individuals tagged, 68 (15%) were recaptured. Time at liberty ranged from 6 days to almost 4 years and all but one of the recaptures were caught in its original tagging location, suggesting site fidelity. The large number of N. cepedianus in these coastal systems over summer indicates that these areas are important habitats for this species and that N. cepedianus may have a significant influence on community dynamics through both direct and indirect predator-prey interactions.

Abundance, age structure and reproductive patterns of Rattus norvegicus and Mus musculus in two areas of the city of Buenos Aires

The aim of this research was to compare the abundance, growth, age structure and reproductive patterns of Rattus norvegicus and Mus musculus populations of a shanty town and a parkland in the city of Buenos Aires, Argentina. Live trapping of rodents was conducted in each area every 2 months, from September 2006 to August 2007. Abundance of R. norvegicus and M. musculus was significantly higher in the shanty town than in the parkland. Abundance of both species showed significant differences between trapping sessions in both study sites. Both species showed a peak in abundance in summer in the parkland and also in autumn in the shanty town. Age structure of both species differed between summer–autumn and winter–spring in the shanty town. In the parkland, pregnant females of both species were only found in spring–summer. No significant differences were found in any of the reproductive parameters compared between the shanty town and the parkland. Our results suggest that the shanty town represents a favourable but not constant habitat for rodents throughout the year.

Seasonal spawning and wind‐regulated retention‐dispersal of early life stage Atlantic cod (Gadus morhua) in a Newfoundland fjord

AbstractSequential ichthyoplankton surveys were used to determine the spatial and temporal distribution of eggs and larvae over coastal spawning grounds of Atlantic cod (Gadus morhua) in Smith Sound, Trinity Bay, Newfoundland, during the spring and summer of 2006 and 2007. Egg densities showed similar patterns for both years with two peaks in abundance in spring (March–April) and late summer (late July). A clear progression of development stages (1–4) was observed in spring and summer in 2006 and summer in 2007, suggesting retention of eggs within the Sound during these periods. Modelled predictions of vertical egg distributions indicated eggs were broadly distributed near the surface during spring (March–April), but were concentrated below the pycnocline (&gt;10 m) within the inner portions of the Sound during the summer months (July–August). Back‐calculated peaks in spawning based on water temperatures were estimated at 11 and 4 April for 2006 and 2007, respectfully, with late season peaks centred on 21–24 July for both years. Environmental data indicated cooler water temperatures and periods of high wind stress in spring, and warmer, calmer periods late summer, consistent with higher retention and faster development times on the spawning grounds later in the season. We conclude that spring and summer spawning events result in different distributions of early life stages and may lead to different distributions of juvenile and adult fish.

The seasonal phenology of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in Queensland

Abstract Bactrocera tryoni is a polyphagous fruit fly, originally endemic to tropical and subtropical coastal eastern Australia, but now also widely distributed in temperate eastern Australia. In temperate parts of its range, B. tryoni populations show distinct seasonal peaks driven by changing seasonal climates, especially changing temperature. In contrast to temperate areas, the seasonal phenology of B. tryoni in subtropical and tropical parts of its range is poorly documented and the role of climate unknown. Using a large, historical (1940s and 1950s) fruit fly trapping dataset, we present the seasonal phenology of B. tryoni at nine sites across Queensland for multiple (two to seven) years per site. We correlate monthly trap data for each site with monthly weather averages (temperature, rainfall and relative humidity) to investigate climatic influences. We also correlate observed population data with predicted population data generated by an existing B. tryoni population model. Supporting predictions from climate driven models, B. tryoni did show year‐round breeding at most Queensland sites. However, contrary to predictions, there was a common pattern of a significant population decline in autumn and winter, followed by a rapid population increase in August and then one or more distinct peaks of abundance in spring and summer. Mean monthly fly abundance was significantly different across sites, but was not correlated with altitudinal, latitudinal or longitudinal gradients. There were very few significant correlations between monthly fly population size and weather variables (either for the corresponding month or for up to 3 months previously) for eight of the nine sites. For the southern site of Gatton fly population abundance was correlated with temperature. Results suggest that although climate factors may be influencing patterns of B. tryoni population abundance in southern subtropical Queensland, they are not explaining patterns of abundance in northern subtropical and tropical Queensland. In the discussion we focus on the role of other factors, particularly larval host plant availability, as likely drivers of B. tryoni abundance in tropical and subtropical parts of its range.

Monsoon-forced distribution and assemblages of appendicularians in the northwestern coastal waters of South China Sea

This study examines species composition and abundance of appendicularians in the northwestern coastal waters of South China Sea based on in situ data obtained by 169 μm planktonic nets during summer and winter, and discusses the influence of environmental factors on their distribution and assemblages. A total of 19 appendicularian species (including one unidentified species) was collected. Species richness is higher in summer than in winter, and it increases from inshore to offshore waters. Average abundance of appendicularians is 103.1 (±198.1) and 54.6 (±111.1) ind. m −3 in summer and winter, respectively. The abundance distribution of appendicularians is generally high around inshore waters during summer and winter, and with a higher abundance assemblage along the eastern coast from Leizhou Peninsula to Hainan Island, especially at the eastern mouth of Qiongzhou Strait in summer. Oikopleurids accounted for 97.5% and 99.6% of total appendicularians abundance in summer and winter, and the region of high values was the same to that of total appendicularians abundance. Oikopleura longicauda, Oikopleura rufescens, and Oikopleura fusiformis are dominant species during summer and winter. Results showed that spatial distribution of species richness of appendicularians is considered to be the result of physical factors such as temperature and salinity in summer and winter, while variations in abundance of appendicularians are affected by the combination of physical and biological factors. In particular, variations of appendicularians abundance are affected by food availability in summer.

Interdecadal changes in at‐sea distribution and abundance of subantarctic seabirds along a latitudinal gradient in the Southern Indian Ocean

AbstractLong‐term demographic studies have recently shown that global climate change together with increasing direct impacts of human activities, such as fisheries, are affecting the population dynamics of marine top predators. However, the effects of these factors on species distribution and abundance at sea are still poorly understood, particularly in marine ecosystems of the southern hemisphere. Using a unique long‐term data set of at‐sea observations, we tested for interdecadal (1980s vs. 2000s) changes in summer abundance and distribution of 12 species of Albatrosses and Petrels along a 30° latitudinal gradient between tropical and Antarctic waters of the southern Indian Ocean. There were contrasting effects of climate change on subantarctic seabird distribution and abundance at sea. While subtropical waters showed the highest rate of warming, the species that visited this water mass showed the greatest changes in distribution and abundance. The abundance of Wandering Albatrosses (Diomedea exulans), White‐chinned Petrels (Procellaria aequinoctialis) and Giant Petrels (Macronectes sp.) declined markedly, whereas the other species showed contrasting trends or did not change. With the exception of the White‐chinned Petrel, these decreases were at least partly related to regional increase in sea surface temperature. The southward shift of Wandering Albatross and Prions (Pachyptila spp.) distributions could be ascribed to species redistribution or decrease in abundance due to warming of the subtropical waters. Surprisingly, White‐chinned Petrel distribution shifted northward, suggesting more complex mechanisms. This study is the first to document a shift in species range in the Southern Ocean related to climate change and contrasting abundance changes. It suggests that some species might experience more severe impacts from climate change depending on the water masses they visit. As climate changes are predicted to continue in the next decades, understanding species responses to climate change is crucial for conservation management, especially when their conservation status is critical or unknown.

Ecology of Georgetown Salamanders (Eurycea naufragia) Within the Flow of a Spring

Abstract The Georgetown salamander, Eurycea naufragia, is a permanently neotenic salamander known only from about a dozen surface springs and caves in Williamson County, Texas. Rapid urbanization places all known populations at risk and conservation strategies are hindered by a lack of information on the ecology of the species. To better understand requirements of microhabitat and spatial distribution of E. naufragia within flows of surface springs, we conducted counts of salamanders on the surface at one locality over a 12-month period. Numbers of salamanders and percentage of cover objects occupied by salamanders varied among months, with a general trend of higher abundance in spring and summer. Few juveniles were observed, and there was no strong seasonal trend in distribution of size of salamanders. Within the flow of the spring, abundance of salamanders decreased linearly with distance from origin of the spring. Salamanders were more likely to be under rocks than under other types of cover objects an...

COMPARATIVE ANALYSIS OF EPIPHYTIC FORAMINIFERA IN SEDIMENTS COLONIZED BY SEAGRASS POSIDONIA OCEANICA AND INVASIVE MACROALGAE CAULERPA SPP.

Mediterranean shallow-water soft bottoms are characterized by extensive meadows of the endemic seagrass Posidonia oceanica (L.) Delile that support abundant benthic biota including numerous epiphytic foraminiferal taxa. The biomass of the epiphytic communities varies with the P. oceanica cycle, especially influencing those taxa with higher abundances in summer, when the foliar surface is maximum. During the past decades exotic macrophyte species have invaded habitats formerly dominated by P. oceanica . Two of these taxa are the green algae Caulerpa taxifolia (Vahl) Agardh, 1817 and C. racemosa (Forsskal) Agardh, 1873, that, along with the non-invasive C. prolifera (Forsskal) Lamouroux, 1809, produce defensive, secondary metabolites such as caulerpenyne that affects turnover rates of P. oceanica leaves. As a consequence of different architectural features of the algal substrate, replacement of P. oceanica by Caulerpa spp. results in the change from a complex three-dimensional, long duration substrate into a simpler, two-dimensional one with a shorter life span. Epiphytic foraminifers can be clustered into functional groups according to their shape, structure, behavior and life span. The foraminiferal dead assemblage includes a total of 110 species, that included 43 species in sediments colonized by P. oceanica , 82 species in sediments with C. prolifera , 78 in sediments invaded by C. taxifolia , and 55 in sediments invaded by C. racemosa . Taxonomic composition of all assemblages is similar, though differences occur in the relative abundance of each taxon. Sediments in P. oceanica meadows are characterized by flat, encrusting, long life-span species (e.g., Planorbulina mediterranensis d’Orbigny, 1826), whereas in Caulerpa spp. habitat, temporarily motile, shorter life-span taxa (e.g., Lobatula lobatula (Walker and Jacob, 1798) and Rosalina bradyi Cushman, 1915) tend to dominate. Multivariate analysis shows that only the thanathocoenosis of P. oceanica sediments is representative of the P. oceanica epiphytic foraminiferal assemblage ( Planorbulinatum medi-terranensae Colom, 1942). Hence, differences among the foraminiferal assemblages in sediments colonized by different phytal substrates occur prior to taphonomic and dissolution processes and may be applicable to paleoecological interpretations.