This paper represents the results of more than 30 years field observations and research work carried out from the Isefjord Laboratory, Vellerup Vig (Zealand, Denmark), which is owned and financed by the author. The Isefjord complex, 36 km long, including the main fjord and the Roskilde Fjord, and covering about 400 km2, is a shallow (7–10 m, max. 30 m) area dominated by substrata of fine sand to mud with a high content of organic matter. As a guidebook for future research the first part gives information about distribution, systematics, ecology, and breeding of the majority of the 477 animal species described. Nearly 400 species are invertebrates and of the chordates 68 species are true fishes. 63% of all animal species have not previously been recorded from the area, 27 species are new to Danish seas, and one (Polychaeta, Capitellidae) is new to science. The hydrography is treated mainly on the basis of literature. The fjord system may be classified as mixohaline: the Isefjord proper is polyhali...

Systematics and ecology of the Isefjord marine fauna (Denmark) with a survey of the eelgrass (Zostera) vegetation and its communities

An overview is presented of non-indigenous marine and estuarine plant and animal species recorded from The Netherlands. In this list both exotic species from outside NW Europe and non-indigenous species from elsewhere in NW Europe are enumerated. Species that have been suggested to be non-indigenous in The Netherlands but for which insufficient evidence could be found are discussed shortly as well. The list is based mainly on literature data supplemented by own observations of the author. At least 99 plant and animal species have been introduced from elsewhere in the world. Another 13 species have been introduced from other parts of NW Europe. The third category of dubious non-indigenous species enumerates 37 species. The list is preceded by an introduction describing the history of Dutch research on introduced species, the origin of the marine and estuarine flora and fauna of The Netherlands, natural and human-induced dispersal processes, and a summary of the geographic patterns of introduced species.

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Non-indigenous marine and estuarine species in The Netherlands

The European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Filifera Part 4. - This study reviews all European hydroids belonging to the filiferan family Eudendriidae. Two new species occurring in the northeastern Atlantic are described: Eudendrium capillaroides new spec. and Eudendrium unispirum new spec. Eudendrium vaginatum Allman, 1863, is redescribed. It is characterized by a special type of nematocysts and traits of the perisarc. It is distinct from Eudendrium annulatum Norman, 1864, which is a separate, valid species. Eudendrium fragile Motz- Kossowska, 1905 and Eudendrium islandicum Schuchert, 2000 are both recognized as synonyms of E. album Nutting, 1898. Eudendrium stratum Bonnevie, 1898 and E. planum Bonnevie, 1898 are both recognized as synonyms of E. rameum (Pallas, 1766). Eudendrium insigne Hincks, 1861 is indistinguishable from E. ramosum and newly collected material from the type locality confirmed this. Eudendrium insigne must thus be regarded as a synonym of E. ramosum (Linnaeus, 1758). A re-examination of the type material of Eudendrium elsaeoswaldae Stechow, 1921 revealed that it is conspecific with E. ramosum (Linnaeus, 1758), becoming thus a new synonym of the latter. Perigonimus multicornis Allman, 1876 is indistinguishable from Myrio - nema hargitti (Congdon, 1906) and must be regarded as a senior synonym of the latter. Because it seems likely that the original type locality designation "Kattegat" was incorrect, it should not replace M. hargitti or M. amboinense.

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The European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Capitata Part 1

Molecular evidence for multiple episodes of paedomorphosis in the family Hydractiniidae

. The history of the study of hydroid ecology is briefly outlined, pointing out the major methodological innovations which have contributed to the development of ecological research in the last thirty years. The influence of the major ecological factors on hydroid ecology and biology is synthesized, taking into account: substratum, water movement, light, salinity, sedimentation, exposure to air, temperature, food availability and pollution. Besides affecting the species composition of the hydroid community, these factors also influence the morphology and general biology of the individual species. The adaptations and reactions of hydroids to different intensities of the various environmental factors and to their combinations are reported.

The ecology of marine hydroids and effects of environmental factors: a review

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George James Allman

Papers

A monograph of the gymnoblastic or tubularian hydroids / by George James Allman.