We redescribe the only previously known species of Myrsidea from bulbuls, M. pycnonoti Eichler. Sixteen new species are described; they and their type hosts are: M. phillipsi ex Pycnonotus goiavier goiavier (Scopoli), M. gieferi ex P. goiavier suluensis Mearns, M. kulpai ex P. flavescens Blyth, M. finlaysoni ex P. finlaysoni Strickland, M. kathleenae ex P. cafer (L.), M. warwicki ex Ixos philippinus (J. R. Forster), M. mcclurei ex Microscelis amaurotis (Temminck), M. zeylanici ex P. zeylanicus (Gmelin), M. plumosi ex P. plumosus Blyth, M. eutiloti ex P. eutilotus (Jardine and Selby), M. adamsae ex P. urostictus (Salvadori), M. ochracei ex Criniger ochraceus F. Moore, M. borbonici ex Hypsipetes borbonicus (J. R. Forster), M. johnsoni ex P. atriceps (Temminck), M. palmai ex C. ochraceus, and M. claytoni ex P. eutilotus. A key is provided for the identification of these 17 species.

A new species

We review the effects of fishing on benthic fauna, habitat, diversity, community structure and trophic interactions in tropical, temperate and polar marine environments and consider whether it is possible to predict or manage fishing-induced changes in marine ecosystems Such considerations are timely given the disillusionment with some fishery management strategies and that policy makers need a scientific basis for deciding whether they should respond to social, economic and political demands for instituting or preventing ecosystem-based management Fishing has significant direct and indirect effects on habitat, and on the diversity, structure and productivity of benthic communities These effects are most readily identified and last longest in those areas that experience infrequent natural disturbance The initiation of fishing in an unfished system leads to dramatic changes in fish community structure As fishing intensity increases the additional effects are more difficult to detect Fishing has accelerated and magnified natural declines in the abundance of many forage fishes and this has lead to reduced reproductive success and abundance in birds and marine mammals However, such donor-controlled dynamics are less apparent in food webs where fishes are the top predators since their feeding strategies are rather more plastic than those of most birds and mammals Fishers tend to target species in sequence as a fishery develops and this leads to changes in the composition of the fished communities with time The dramatic and apparently compensatory shifts in the biomass of different species in many fished ecosystems have often been driven by environmental change rather than the indirect effects of fishing Indeed, in most pelagic systems, species replacements would have occurred, albeit less rapidly, in the absence of fishing pressure In those cases when predator or prey species fill a key role, fishing can have dramatic indirect effects on community structure Thus fishing has shifted some coral reef ecosystems to alternate stable states because there is tight predator–prey coupling between invertebrate feeding fishes and sea urchins Fishing has reduced, and locally extirpated, populations of predatory fishes These reductions do not have a consistent effect on the abundance and diversity of their prey: environmental processes control prey populations in some systems, whereas top-down processes are more important in others By-catch which is discarded during fishing activities may sustain populations of scavenging species, particularly seabirds We conclude by identifying the circumstances in which new research is needed to guide managers and stress the importance of unfished control sites for studies of fishing effects We discuss the advantages and disadvantages of closed area management (marine reserves) and the conditions under which such management is likely to provide benefits for the fishery or ecosystem

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The effects of fishing on marine ecosystems

Sibling species are common in all major marine groups and habitats. Their abundance reflects both inadequate study of morphological features of living organisms ("pseudo-sibling species") and divergence in habitat, life history, and chemical recognition systems without parallel divergence in morphology. Many marine sibling species are quite distinct genetically. Others, however, exhibit slight genetic differences whose significance is only clear in sympatry and in combination with other subtle but concordant patterns of differentiation. A large number of abundant, well-studied, or economically important taxa have recently been shown to be complexes of sibling species. The broad habitat and geographic distributions characteristic of many marine species require reevaluation in this context.

Sibling species in the sea

Electrophoretic data were analysed from 49 species of freshwater fish, 57 species of marine fish, and seven anadromous species. For each species, at least 15 individuals had been assayed for at least 15 loci in two or more subpopulations. The results showed that while average total heterozygosity (HT) was approximately equal in freshwater and marine species (0·062 and 0·064 respectively), subpopulation heterozygosity (Hs) was significantly less in the former group (0·046 and 0·059 respectively). Consequently the average degree of genetic subpopulation differentiation (HST) was significantly greater for freshwater species (0·222 v. 0·062). On average, it is likely that marine subpopulations exchange between 10 and 100 times more migrants per generation than freshwater subpopulations, presumably because of the relative absence of barriers to dispersal in the marine environment. The reduced values of Hs in freshwater species are likely to reflect reduced effective subpopulation sizes relative to marine species. The few andromous species that have been analysed show intermediate levels of GST.

A comparison of genetic diversity levels in marine, freshwater, and anadromous fishes

Many studies have shown that seabirds are sensitive to changes in food supply, and therefore have potential as monitors of fish stocks. For most seabird species breeding parameters suitable for biomonitoring have yet to be measured over a wide range of prey densities. However, it is clear that responses vary among species and care must be taken when interpreting seabird data as a proxy for fish abundance. For many years seabirds have also been used as monitors of pollution, especially oil pollution. Beached bird surveys provide important evidence of geographical and temporal patterns, and, for example, show consistent declines in oil release into the southern North Sea over the last 15 years. Analysis of oil on birds can now permit fingerprinting of sources, allowing prosecution of polluters. As predators high in marine food webs, seabirds also have potential as monitors of pollutants that accumulate at trophic levels. Recent work on mercury in seabirds has permitted an analysis of spatial patterns and of the rates of increase in mercury contamination of ecosystems over the last 150 years, since mercury concentrations in feathers of museum specimens can be used to assess contamination in the birds when they were alive. Surprisingly, pelagic seabirds show higher increases than most coastal ones, and increases have been greatest in seabirds feeding on mesopelagic prey. This seems to relate to patterns of methylation of mercury in low-oxygen, deeper water. Accurate measurement of long-term trends in mercury contamination depend on the assumption that seabird diet composition has not changed. This can be assessed by analysis of stable isotopes of N and C from the same feathers used for mercury measurement, a technique that also permits the monitoring of trophic status over time or between regions. While high mercury contamination of seabirds in the southern North Sea is unsurprising, we cannot yet explain certain unexpected results, such as high levels in seabirds from north Iceland compared with those from south Iceland or Scotland.

Seabirds as monitors of the marine environment

The Food, Growth and Fledging Success of Norwegian Puffin Chicks Fratercula arctica in 1980-1983

Published and unpublished records of amp hip od-sea anemone associations are reviewed. They involve at least 22 amphipod species in 7 families, and 8 families of sea anemones. The associations are of 4 main types: protection only, ectocommensals, endocommensals and micropredators. Morphological adaptations are not conspicuous, except for the specialised mouthparts of Acidostoma spp., but most obligate symbionts show inborn immunity against the toxic substances released by the host. Sex ratios are normal, sexual dimorphism small, and fecundity low compared to related free-living species. The obligate commensal associates are usually host-specific, although able to survive in alternative hosts in the laboratory, while the micropredators and the facultative associates show low host specificity. The amphipod symbionts usually do not occupy the entire geographical and ecological range of their hosts' distribution. Amphipod-sea anemone associations have evolved independently many times and do not seem to be of great evolutionary antiquity.

Associations between amphipods (Crustacea: Amphipoda) and sea anemones (Anthozoa: Actiniaria)

1. The first Norwegian specimens of the lysianassid amphipod Acidostoma nodiferum Stephensen are recorded, and the distribution of the species is mapped. The animals were collected in association with the sea anemone Actinostola callosa (Verrill), which is in agreement with recent anatomical work suggesting ectoparasitical habits for species of Acidostoma. 2. The Norwegian records of the photid amphipod Leptocheirus hirsutimanus (Bate) are enumerated, and some notes given on a specimen recently collected near Bergen. Earlier reports of the occurrence of L. pilosus Zaddach in Norway are erroneous, but both this species and L. pectinatus (Norman) may eventually be found in Norwegian waters, judging from their distribution in NW Europe. 3. The lysianassid amphipod Onisimus normani G. O. Sars is shown, both from scattered notes in the literature and from recent observations near Bergen, to be a regular associate of a number of large sea anemone species. The distribution of O. normani is mapped and so...

Notes on Norwegian marine amphipods 1–3

The taxon Caprella acanthifera auct., usually considered to be one ‘highly variable’ species, is shown here to consist of a number of closely related species. In this paper three species of the group lacking an axillary spine near the insertion of gnathopod 2 are described and illustrated; the taxa with an axillary spine will be dealt with in a separate paper. This paper redefines Caprella acanthifera Leach 1814, sensu stricto; the nominal taxa C. hystrix, C. calva, C. aspera, and C. leptonyx are considered to be junior synonyms. Also described are C. stella sp.n., from starfish at the Azores and C. cavediniae sp.n., living among algae in the Mediterranean. The sources of apparent morphological variability in caprellids are discussed.

What is, and what is not, Caprella acanthifera Leach, 1814 (Amphipoda, Caprellidea)? Part 1: the acanthifera-group

Correlations between guillemots (including Common Guillemots Uria aalge and Brunnich's Guillemots U. lomvia) and their prey (divided into five prey categories, capelin Mallotus villosus, herring Clupea harengus, polar cod Boreogadus saida, plankton, and a mixture of other prey species) at two depths (10-100 m and 100-200m) were estimated along an extended transect of 3,060 nautical miles (5,667 km) in the Barents Sea in April/May 1986. Spatial concordance was highest during daylight hours when the largest number of birds were seen on water (presumably feeding birds). Capelin was the single prey category which was most often associated with birds but no single prey category could alone explain the distribution of birds. Although only a small fraction of guillemots could be identified to species, there was some evidence that capelin were of greater importance to Common than to Brunnich's Guillemots. Overall correlation between birds and total prey density was statistically significant at the smallest scale of 5 nautical miles (n.m.). The removal of herring from the calculations increased the strength of the correlation. The depth at which prey was located had little effect on the distribution of birds. The correlation between birds and prey was scale dependent, and reached a maximum at 90 n.m., although there seemed to be some upper threshold in the coefficient at c. 40 n.m. Numerical concordance (including only 5 n.m. periods where both prey and birds were present) was significant at the 5 n.m. scale but was higher for high density than for low density prey patches. The results are discussed in relation to the few similar studies in other oceans and in relation to the severe reduction of important prey species in the Barents Sea.

Wim Vader

Papers

The Food, Growth and Fledging Success of Norwegian Puffin Chicks Fratercula arctica in 1980-1983

Associations between amphipods (Crustacea: Amphipoda) and sea anemones (Anthozoa: Actiniaria)

Notes on Norwegian marine amphipods 1–3

What is, and what is not, Caprella acanthifera Leach, 1814 (Amphipoda, Caprellidea)? Part 1: the acanthifera-group

Correlations between pelagic distribution of Common and Brünnich's Guillemots and their prey in the Barents Sea