Spatial and temporal distribution of freshwater sponges in Connecticut lakes based upon analysis of siliceous spicules in dated sediment cores

A survey of 28 Connecticut water bodies for spicular remainsoffreshwater sponges preserved in lacustrine sediments revealed14species representing 10 genera. Sediments were examined atfivelevels (ca 1991, ca 1970, ca 1934, ca 1890, ca 1875)todocument changes in species composition, distribution, andabundance. Five species were recorded statewide in all fivegeologic regions: Spongilla lacustris, Heteromeyeniatubisperma, Anheteromeyenia ryderi, Eunapius fragilis, andEphydatia muelleri. Spongilla lacustris was the mostcommonand widely distributed species. Factors that may havecontributedto the observed distribution of the spongillids in Connecticutareregional differences in lake water chemistries, individualspeciestolerances, and differences in extent of dispersal of variousspecies. Most of the more abundant species are widelydistributedwith respect to water quality parameters. Anheteromeyeniaargyrosperma, Duosclera mackayi and Trochospongillapennsylvanica appear to be restricted to waters exhibitingthelower ranges for conductivity, alkalinity and calcium content.Ingeneral, a greater number of spicules was found in bottomsedimentsof the surveyed lakes as compared with the surface sediments.Oftenthis was correlated with increased sediment accumulation ratesinmore recent periods. When this fact is taken into account, itappears that populations of a number of sponge species haveremained relatively constant in many of the lakes over thepastcentury. However, in some lakes exhibiting lower or onlyslightlyhigher sediment accumulation rates at the surface, fewerspiculeswere also found in more recent sediments, suggesting an actualdecline in sponge population sizes. Changes in abundance overthelast 100 years may be related to changes in land use practicesinsurrounding watersheds and the associated changes in waterchemistries.     

Abundance and microhabitats of freshwater sponges (Spongillidae) in a Danubean floodplain in Austria

1. This study examined the abundance and distribution of freshwater sponges (Spongillidae) at 32 sites in a floodplain on the Danube within the ‘Donau‐Auen’ National Park east of Vienna, Austria. Ranked from abundant to rare, the species inventory comprised Ephydatia fluviatilis, Spongilla lacustris, Ephydatia mülleri, Eunapius fragilis and Trochospongilla horrida. 2. The presence of hard substratum was essential for the growth of sponges. Timber stands near the water and drifting dead wood increased the abundance of E. fragilis, E. fluviatilis and E. mülleri, whereas stony substrata were important for S. lacustris. A small fraction of E. fluviatilis was collected from macrophytes (Phragmites). 3. Based on the area colonised, the abundance of S. lacustris, E. fragilis and E. fluviatilis was highest (94.2–100% of the total) in floodplain waters where hydrological connectivity with the Danube was low (0–6 days year⁻¹), whereas E. mülleri and T. horrida made up 20.3–35.9% of the total at sites connected for up to 179 days year⁻¹. Moreover, the area colonised by T. horrida at a current velocity >0.20 m s⁻¹ was larger than in the remaining species. Sites with E. mülleri and T. horrida had a higher silicon concentration (0.9 mg L⁻¹) than sites where the remaining three species were collected (0.4–0.6 mg L⁻¹). 4. In most species, the length of macroscleres (the larger spicules) was positively correlated with conductivity and negatively with pH. With respect to aberrant macroscleres, hooks were observed most frequently, whereas the proportion of centrotylotes (ie with the one on more globular swellings along the spicule) was lowest. 5. Freshwater sponges have a great deal of potential as bioindicators and restoration measures that improve floodplain connectivity will favour rare species, such as E. mülleri and T. horrida, while impairing others (e.g. E. fragilis, S. lacustris and E. fluviatilis).     

Xenochironomus ceciliae (Diptera: Chironomidae), a new chironomid species inhabiting freshwater sponges in Brazil

Chironomids living inside freshwater sponges are scarcely known, particularly in the Neotropical region where most of them are to be described. Here, male and female adults, pupa and 4th instar larva of Xenochironomus ceciliae sp. n., living in freshwater sponges of the Paraná River (Brazil) are described. The larval labrum with its several densely setose or combed structures somewhat resembling the filtering structures of simuliid larvae and the predominance of fine detritus in the larval gut contents, may indicate that the larvae of Xenochironomus ceciliae sp. n. are collector-filterers and they might be favored by the aquifer systems of the sponges.     

Biogeography and ecology of freshwater diatoms in Subantarctica: a review

Subantarctica is situated between the Antarctic and the Subtropical Convergence and consists of the islands in the southern Atlantic, Indian and Pacific Oceans. Diatoms are an important component of all Subantarctic aquatic, moss and soil habitats. Taxonomic studies reveal a high diversity and species richness in both the present-day and the fossil diatom flora. Planktonic diatoms are almost completely absent. A similarity analysis of the diatom composition from different localities in the southern zone (below 40°S) resulted in a biogeographical zonation. Three regions could be formed, based on their diatom composition: Subantarctica, Maritime Antarctica and the Antarctic Continent. The diatom communities in the different regions are all characterized by a high proportion of cosmopolitan species. A second feature of the southern diatom floras is the decreasing diversity when moving southwards.     

淡水螯虾生理生态学与环境毒理学研究进展

综述了我国2种主养的淡水螯虾(克氏原螯虾和红螯螯虾)在生理生态学与环境毒理学方面的研究进展。总结了淡水螯虾的环境条件(盐度、温度和pH)适应范围、毒性污染物(氨氮、亚硝酸盐、重金属和农药等)的半致死浓度和安全浓度,以及环境胁迫和毒性污染物暴露对淡水螯虾生长、组织结构、生理代谢和免疫功能等的影响,为淡水螯虾养殖的水环境监测与调控提供参考依据。     

Reproductive processes in sponges: a critical evaluation of current data and views

The nature of a number of fundamental processes occurring during reproduction in sponges still remains in doubt. Among the more significant of these are: the true status of sponges described as dioecious, namely whether some are actually successive hermaphrodites; the origin of oogonia, which have recently been claimed to be derived from choanocytes; the origin and mechanism of formation of large spermatogenic masses; the specific pathway leading to fertilization taken by sperm cells within the sponge tissue of viviparous species; the role played during larval metamorphosis by somatic cells which are incorporated into embryos; the cell lineage of choanocytes which form flagellated chambers during larval metamorphosis; the specific relationship of somatic growth and dormancy to gametogenesis; the role of budding and fragmentation in population maintenance; the role, if any, of gemmules in dispersion. It is considered mandatory that new techniques be developed in order to further elucidate these and other reproductive processes and to gather definitive data concerning them. The employment of only microscopic techniques is ultimately insufficient for investigating the dynamic relationships of reproductive processes.     

淡水鱼类功能生态学研究进展

在全球变化和人类活动的影响下,生物多样性正以前所未有的速度丧失,全球生物正经受第六次生物多样性危机。淡水生态系统是最脆弱的生态系统之一。淡水鱼类作为淡水生态系统的重要组成部分,承受着日趋严重的气候变化、栖息地退化、生物入侵和过度捕捞等压力,面临巨大的威胁。在此背景下,如何准确评估鱼类种群和群落对环境变化的响应,以及鱼类群落结构和功能的变化对生态系统功能的影响是淡水鱼类多样性和淡水生态系统保护的关键问题。近年来,淡水鱼类功能生态学的快速发展为解答这一问题提供了一个框架。系统地介绍了淡水鱼类功能生态学主要研究内容、方法、进展及其应用,并着重介绍了淡水鱼类功能特征及其与环境的关系、环境变化下的功能生态学响应研究。据此提出了淡水鱼类功能生态学未来的重点研究方向,指出了其在鱼类多样性保护和资源利用等领域的应用前景。     

Collaboration in scientific research: a critical need for freshwater ecology

1. Collaboration means actively working together to achieve things which could not be done alone. This article attempts to provide an overall, unified, guiding framework for collaboration in freshwater ecology by discussing aspects of collaboration at individual and organizational levels, and addressing international linkages.
2. The essential elements of collaboration are communication and trust, and effective project management. Barriers to effective collaboration include competition, organizational cultures and organizational instabilities.
3. The success of collaboration can be measured by tangible benefits such as increased numbers of peer-reviewed publications, the production of working models and a number of intangible benefits.
4. Interactions between individuals lie at the heart of an effective collaboration; organizational arrangements should facilitate this interaction. Some governments are encouraging collaboration to increase cost efficiency and allocate accountability. This trend should continue on an international level.
5. Collaboration is a key to future research in freshwater ecology.     

The ecology of the Turbellaria with special reference to the freshwater triclads

To attempt a complete review of turbellarian ecology in the time and space available would result in superficiality. Therefore, I have restricted this account to the four basic ecological processes which have and continue to determine flatworm distribution and abundance. These are: (1) historical or zoogeographical events which permit or prevent a species from reaching a habitat; (2) physiological limitations of the species vis à vis the habitat; (3) access to suitable energy sources and (4) the effects of competition, predation and parasitism, referred to collectively as bionomic processes.     

A continuous-flow system for growing fresh-water sponges in the laboratory

Two fresh-water sponge species, Ephydatia fluviatilis and Spongilla alba, were grown from gemmules in the laboratory. A system incorporating a continuous flow of filtered habitat water and live bacteria from a chemostat culture as a food source were used. Experiments with this system demonstrated a relationship between the concentration of bacteria and sponge growth rate. Because the continuous flow of water eliminates the effects of substances released by sponges and growth rate can be predicted for a given bacterial concentration, this system permits experimental studies which were not feasible in the past.     

New trends in phospholipid class composition of marine sponges

The exceptional ability of marine sponges to adapt to often drastic changes of their environments could be due to special structural features in cell membranes, including firstly phospholipids (PL). Thus, PL class composition was investigated in marine sponges (22 species from 19 genera to 15 families) originating from various locations (East Atlantic, North Atlantic, South-West Pacific, Mediterranean Sea, Red Sea, Arabian–Persian Gulf). The quantitative determination of PL class composition was obtained by high-performance thin-layer chromatography (HPTLC) with scanning densitometry of the different spots. Previous reports have shown phosphatidylethanolamine (PE) as the major PL class in marine sponges, followed by phosphatidylcholine (PC), while other papers described PC as a minor class and even lacking. This survey found PE as the major PL class in only two species, while PC was the major class in 13 species including a calcareous one. The great abundance of bacteria in some sponges was evidenced from the relatively high proportions of particular PL classes. Various PL distributions were observed even for the sponge species collected in the same area and belonging to the same genus. Thus, no clear rule on PL composition in marine sponges can be stated to date.     

First report on chitinous holdfast in sponges (Porifera)

A holdfast is a root- or basal plate-like structure of principal importance that anchors aquatic sessile organisms, including sponges, to hard substrates. There is to date little information about the nature and origin of sponges’ holdfasts in both marine and freshwater environments. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within holdfasts of the endemic freshwater demosponge Lubomirskia baicalensis. Using a variety of techniques (near-edge X-ray absorption fine structure, Raman, electrospray ionization mas spectrometry, Morgan–Elson assay and Calcofluor White staining), we show that chitin from the sponge holdfast is much closer to α-chitin than to β-chitin. Most of the three-dimensional fibrous skeleton of this sponge consists of spicule-containing proteinaceous spongin. Intriguingly, the chitinous holdfast is not spongin-based, and is ontogenetically the oldest part of the sponge body. Sequencing revealed the presence of four previously undescribed genes encoding chitin synthases in the L. baicalensis sponge. This discovery of chitin within freshwater sponge holdfasts highlights the novel and specific functions of this biopolymer within these ancient sessile invertebrates.     

Bdellovibrio-like parasite of cyanobacteria symbiotic in marine sponges

A bdellovibrio-like bacterium was observed infecting unicellular symbiotic cyanobacteria in two coral reef sponges, Neofibularia irata and Jaspis stellifera. The infecting bacterium, which was located between the cell wall and the cytoplasmic membrane of the cyanobacteria, was similar in size and appearance to previously described bdellovibrios. This observation is believed to extend the host range of the bdellovibrios.     

Sterols from sponges of Anavilhanas

Sponges present a wide variety of metabolites, and are considered one of the hotspots in research on the chemistry of natural products. Sterols from sponges have received attention because they present patterns of branches that distinguish them from all other living organisms. Freshwater sponges, native to rivers and lakes, have been studied chemically throughout the world, but there have been no studies on sponges from the Amazon region. The present work describes the sterols present in freshwater sponges collected in Anavilhanas, the world's second largest river archipelago, in the Negro river (Amazonas-Brazil), focussing on species whose family has not been studied previously in regard to their chemistry of natural products. Using a set of derivatization reactions for identification by chromatographic and spectrometric techniques, it was observed that the steroid extracts of sponges of the species Metania reticulata, Drulia browni and Drulia uruguayensis (Metaniidae) present 24-ethyl-cholest-5,22-dien-3β-ol as the principal sterol. Cholesterol, the main sterol in Spongillidae and Lubomirskiidae, was already detected but as a minor component along with three other sterols.     

Spongiopsyllus adventicius new species and genus of Entomolepididae (Copepoda: Siphonostomatoida) associated with sponges in Brazil

Spongiopsyllus adventicius n. gen., n. sp. is a siphonostomatoid copepod found associated with sponges from Bahia and Pernambuco states, northeast of Brazil. The new genus has three postgenital urosomites in females and four in males, while all the other genera in the family have no more than two and three postgenital urosomites in females and males, respectively.     

Chemical defenses against diatom fouling in Antarctic marine sponges

Antarctic sponges are commonly fouled by diatoms, sometimes so heavily as to occlude pores employed in filter feeding and respiration. This fouling becomes heavier during the annual summer microalgal bloom. Polar and non‐polar extracts of eight species of marine sponges from McMurdo Sound, Antarctica were assayed for cytotoxicity against sympatric fouling diatoms. To identify compounds potentially released by sponges as defenses against diatom biofouling, only fractions of crude extracts that were soluble in seawater or 2% methanol in seawater were assayed. Significant bioactivity was present in seven of the eight species. Both Mycale acerata and Homaxinella balfourensis displayed moderate levels of defense against diatoms even though they are not or are only weakly chemically defended against bacteria and predators. Calyx acuarius extracts, which do have antipredator and antibacterial effects, had no effect on diatoms except at levels many fold higher than present in the intact animal. These results strongly suggest some level of specificity for chemical defenses against diatom fouling in antarctic sponges.     

Metagenomic approaches to exploit the biotechnological potential of the microbial consortia of marine sponges

Natural products isolated from sponges are an important source of new biologically active compounds. However, the development of these compounds into drugs has been held back by the difficulties in achieving a sustainable supply of these often-complex molecules for pre-clinical and clinical development. Increasing evidence implicates microbial symbionts as the source of many of these biologically active compounds, but the vast majority of the sponge microbial community remain uncultured. Metagenomics offers a biotechnological solution to this supply problem. Metagenomes of sponge microbial communities have been shown to contain genes and gene clusters typical for the biosynthesis of biologically active natural products. Heterologous expression approaches have also led to the isolation of secondary metabolism gene clusters from uncultured microbial symbionts of marine invertebrates and from soil metagenomic libraries. Combining a metagenomic approach with heterologous expression holds much promise for the sustainable exploitation of the chemical diversity present in the sponge microbial community.