Diversity, structure and function of fish assemblages associated with Posidonia oceanica beds in an area of the eastern Mediterranean Sea and the role of non-indigenous species

Temporal and spatial variation in density, biomass and body size of littoral fish species associated with nearshore Posidonia oceanica meadows was studied over an annual cycle in an area of the eastern Mediterranean Sea. A total of 109,350 littoral fishes were collected, belonging to 34 families and 88 species. Density of fishes peaked during the summer due to high numbers of juveniles. Season was a significant factor determining density, although number of species and biomass did not show any obvious seasonal pattern. Throughout the study, schooling planktivorous fish species such as the picarel Spicara smaris, the bogue Boops boops and the damselfish Chromis chromis were dominant, both in terms of density (80%) and biomass (70%). Temporal variation in density and body size of fishes was used to assess the seasonal and ontogenetic habitat use of each species, with their affinity to seagrass assessed by comparing their respective distribution on sand. Four functional guilds were created (juvenile migrants, seagrass residents, seasonal migrants and occasional visitors) to describe the habitat use of P. oceanica meadows by each species. Several species associated with P. oceanica meadows used this habitat mainly as juveniles during summer, although many others were present concurrently as adults and as juveniles. Among the species encountered, 11 were non-indigenous of Indo-Pacific origin, of which three used seagrasses mainly as juveniles and four as residents. The non-indigenous silverstripe blaasop Lagocephalus sceleratus ranked among the 10 most dominant species in terms of biomass (2%) and was classified as a seagrass resident.     

Effects of marine reserve characteristics on the protection of fish populations: a meta-analysis

Meta-analyses of published data for 19 marine reserves reveal that marine protected areas enhance species richness consistently, but their effect on fish abundance is more variable. Overall, there was a slight (11%) but significant increase in fish species number inside marine reserves, with all reserves sharing a common effect. There was a substantial but non-significant increase in overall fish abundance inside marine reserves compared to adjacent, non-reserve areas. When only species that are the target of fisheries were considered, fish abundance was significantly higher (by 28%) within reserve boundaries. Marine reserves vary significantly in the extent and direction of their response. This variability in relative abundance was not attributable to differences in survey methodology among studies, nor correlated with reserve characteristics such as reserve area, years since protection, latitude nor species diversity. The effectiveness of marine reserves in enhancing fish abundance may be largely related to the intensity of exploitation outside reserve boundaries and to the composition of the fish community within boundaries. It is recommended that studies of marine reserve effectiveness should routinely report fishing intensity, effectiveness of enforcement and habitat characteristics.     

Evidence of artisanal fishing impacts and depth refuge in assemblages of Fijian reef fish

Protection from fishing generally results in an increase in the abundance and biomass of species targeted by fisheries within marine reserve boundaries. Natural refuges such as depth may also protect such species, yet few studies in the Indo Pacific have investigated the effects of depth concomitant with marine reserves. We studied the effects of artisanal fishing and depth on reef fish assemblages in the Kubulau District of Vanua Levu Island, Fiji, using baited remote underwater stereo-video systems. Video samples were collected from shallow (5–8 m) and deep (25–30 m) sites inside and outside of a large old marine reserve (60.6 km², 13 years old) and a small new marine reserve (4.25 km², 4 years old). Species richness tended to be greater in the shallow waters of the large old reserve when compared to fished areas. In the deeper waters, species richness appeared to be comparable. The difference in shallow waters was driven by species targeted by fisheries, indicative of a depth refuge effect. In contrast, differences in the abundance composition of the fish assemblage existed between protected and fished areas for deep sites, but not shallow. Fish species targeted by local fisheries were 89% more abundant inside the large old reserve than surrounding fished areas, while non-targeted species were comparable. We observed no difference in the species richness or abundance of species targeted by fisheries inside and outside of the small new reserve. This study suggests that artisanal fishing impacts on the abundance and species richness of coral reef fish assemblages and effects of protection are more apparent with large reserves that have been established for a long period of time. Observed effects of protection also vary with depth, highlighting the importance of explicitly incorporating multiple depth strata in studies of marine reserves.     

Dynamics in a butterfly–plant–ant system: influence of habitat characteristics on turnover rates of the endangered lycaenid Maculinea alcon

Abstract.  1.  Maculinea alcon , a myrmecophilic, stenotopic lycaenid butterfly is restricted to wet heathlands, bogs, and nutrient-poor hay meadows. Due to intensification of agriculture and decrease of extensively grazed meadows, many suitable habitats have disappeared and the remaining ones are highly fragmented and deteriorated.
2. Historical distribution data and a comparison with the present occupation of patches show the decline of this critically endangered butterfly in north-west Germany. Most of the populations in north-west Germany are small and often geographically isolated.
3. In summer 2002, two-thirds of 77 investigated potential patches were unoccupied as a result of unsuitable habitat structure and habitat fragmentation.
4. Several habitat parameters were highly significantly correlated with the presence of M. alcon , in particular the distribution pattern of the host plant Gentiana pneumonanthe. Furthermore, butterflies were absent from many patches with an incidence probability below 50% with respect to patch size and isolation.
5. In the nature reserve Lüneburger Heide, part of the study area, M. alcon populations have been observed since 1995. Typical turnover of local populations could be detected during these years. Extinctions and re-colonisations have stabilised the presence of this species in a metapopulation in this nature reserve.
6. These data show the importance of different factors on different spatial levels influencing the presence of this endangered butterfly.     

Spatial patterns of genetic diversity in Posidonia oceanica, an endemic Mediterranean seagrass

Posidonia oceanica is an endemic seagrass species in the Mediterranean Sea. In order to assess levels of genetic structure in this species, the microsatellite polymorphism was analysed from meadows collected in several localities, along the coasts of the Tyrrhenian Sea (Mediterranean Sea). The existence of single population units and the recruitment of seedlings collected in some localities were investigated. Moreover, genetic structure at different spatial scales and biogeographic relationships among populations were also assessed. Our analysis showed the existence of clear patterns of genetic structure in P. oceanica in the area considered in the analysis. P. oceanica, in fact, is present in separate meadows that represent discrete populations, characterized by low genetic diversity. Comparable levels of genetic variability between mature meadows and seedlings were found. Patterns of genetic relatedness among populations seem to be in accord with direction of dominant current flux in the whole area, separating South Tyrrhenian from North Tyrrhenian populations. Moderate levels of gene flow between populations and genetic substructure within populations, together with the finding of the limited role of sexual reproduction in increasing genetic variability, should be a cause for concern for the persistence of this essential resource in the Mediterranean basin.     

New records of marine Tardigrada in the Mediterranean Sea

Meiofauna from Chafarinas archipelago (western Mediterranean, N. Africa) were studied, and marine Tardigrada were identified to species level. A total of 15 species, belonging to families Stygarctidae, Halechiniscidac (Subfamilies Halechiniscinae, Florarctinae, Styraconyxinae and Tanarctinae), Batillipedidae, and Echiniscoididae, were found for the first time from the Alboran Sea and southwestern Mediterranean area. Four species and one subspecies are new records for the Mediterranean Sea: I'ioractus acer, F. asper, P. stellatus, Actinarctus doryphorus and Echiniscoides sigismundi hispaniensis. The male of Floractus stellatus , previously unknown to science, is described. Many species have been recorded for the first time in different sedimentary environments, such as midlittoral pools, very shallow gravels, pools in a mixed rocky environment or between Posidonia oceanica meadows, 'Amphioxus' gravels, and coastal detritic.     

Fish assemblages of Cais do Carvão Bay (Madeira Island) determined by the visual census technique

Fish assemblages in Cais do Carvão Bay, Madeira Island, a proposed marine protected area (MPA), were determined from a diver visual census. A total of 32 transect counts were performed. Habitats sampled included sandy bottom, rocky boulders, vertical walls and rocky outcrops. Species richness, diversity, density, trophic structure, size and spatial organization were documented for the fish assemblages. Forty‐four species from 23 families were encountered; 32% belonged to Sparidae (10) and Labridae (four). The greatest species richness (25) was observed in rocky boulder habitat at 10–15 m depth, while the lowest (five) occurred over a deeper sand habitat. The greatest density (760·5 individuals per 100 m²) was recorded over rocky outcropping (20–25 m deep), and the lowest of 11·6 individuals per 100 m² was over a sand bottom at 10–15 m depth. Thalassoma pavo , Abudefduf luridus and Chromis limbata had higher densities on hard bottoms, while Heteroconger longissimus was the most abundant species in sand bottom habitats. No significant differences were detected for all indices calculated among depth intervals for sand and rocky boulder stations. Sand and rock boulder substratum, however, differed significantly for the 10–15 m depth stratum.     

Distribution and Density of Tsetse Flies (Glossinidae: Diptera) at the Game/People/Livestock Interface of the Nkhotakota Game Reserve Human Sleeping Sickness Focus in Malawi

In large parts sub-Saharan Africa, tsetse flies, the vectors of African human or animal trypanosomiasis, are, or will in the foreseeable future, be confined to protected areas such as game or national parks. Challenge of people and livestock is likely to occur at the game/livestock/people interface of such infested areas. Since tsetse control in protected areas is difficult, management of trypanosomiasis in people and/or livestock requires a good understanding of tsetse population dynamics along such interfaces. The Nkhotakota Game Reserve, an important focus of human trypanosomiasis in Malawi, is a tsetse-infested protected area surrounded by a virtually tsetse-free zone. The abundance of tsetse (Glossina morsitans morsitans) along the interface, within and outside the game reserve, was monitored over 15 months using epsilon traps. A land cover map described the vegetation surrounding the traps. Few flies were captured outside the reserve. Inside, the abundance of tsetse at the interface was low but increased away from the boundary. This uneven distribution of tsetse inside the reserve is attributed to the uneven distribution of wildlife, the main host of tsetse, being concentrated deeper inside the reserve. Challenge of people and livestock at the interface is thus expected to be low, and cases of trypanosomiasis are likely due to people and/or livestock entering the reserve. Effective control of trypanosomiasis in people and livestock could be achieved by increasing the awareness among people of dangers associated with entering the reserve.     

Woody vegetation composition and diversity in woodlands inside and outside a Forest Reserve in Jos,Nigeria

Protected areas such as forest reserves are often assumed to be best ways to conserve biodiversity and maintain intact ecosystems. We examined woody plant composition and diversity in the gallery forest and savannah woodland habitats of Amurum Forest Reserve and areas immediately surrounding it in Jos, Nigeria. A total of 100 10 × 10 m sample plots were established inside and outside the reserve. All woody plants ≥1 cm diameter at breast height (dbh) were identified and measured. A total of 7,564 individual plants categorized as 134 species from 44 families were recorded. Overall species diversity was significantly higher in the Forest Reserve than outside the reserve, although more species were encountered outside the reserve. Our findings suggest that, protected areas and the areas surrounding them are important for the conservation of biodiversity as the areas outside protected areas also contain species of conservation value. The continuous degrading areas outside protected areas isolates them and poses a serious threat to the long‐term viability of wildlife populations, so it is important that biodiversity in protected areas and their surrounding areas be conserved.     

Population structure of Gobius bucchichii, in a Mediterranean marine reserve and in an unprotected area

Gobius bucchichii , in a protected area lived longer than those outside the reserve. Our findings emphasize the cryptic role played by marine protected areas on ecosystems.     

Life-history changes in exploited reef fishes on the east coast of South Africa

Synopsis The impact of exploitation on various life-history characteristics of two sex changing, reef-dwelling sparid species was examined by comparing populations protected in a large marine reserve with those adjacent to the reserve. Like other sparids, Chrysoblephus laticeps and C. cristiceps grow slowly and are long lived, reaching ages of 17 and 21 years, respectively. No significant differences in the growth rate of C. laticeps were measured, but growth in C. cristiceps was significantly slower in the exploited population. Observed data showed that sex ratios outside the marine reserve were skewed towards the females, a result of size selective exploitation. Size at sex change was also significantly smaller for C. cristiceps in the exploited area, but not so for C. laticeps. This difference between the species was explained as a function of the size at recruitment into the fishery and the degree of protection afforded both large females and male fish. Considering the possibility that reproduction could be impaired as a result of changes in population structure, the tactic of protection through marine reserves is supported as a hedge against recruitment failure.     

Distribution and dynamics of Posidonia oceanica beds along the Albères coastline

The location and dynamics of Posidonia oceanica beds were studied in the marine natural reserve of Cerbère-Banyuls-sur-Mer (eastern Pyrenees, France), through the mapping of bottom assemblages (transects and image processing) and the monitoring of fixed markers installed at the Posidonia oceanica lower limit. The surface area occupied by continuous beds is relatively limited and localized, whereas the presence of important areas of dead 'matter' would seem to indicate that bottom cover by Posidonia oceanica was more extensive in the past. Although the limited extension of the seagrass beds seems to be linked to both a high level of turbidity and severe hydrodynamic conditions, it is hypothesized that the regressions observed are due to lack of sediment.     

西双版纳片断山地雨林蚁科昆虫群落研究

西双版纳是中国具有热带雨林的３个地区之一。采用样地调查法对西双版纳自然保护区山地雨林和３块山地雨林片断的蚂蚁群落作了比较研究。目的是揭示保护区与各片断间距离对蚂各落的影响。在４种样地中共计采集蚂蚁６亚科３５属７４种。与保护区距离不等的片断各有自己的特有种（１０－１１种）,各片断的特圾种少于自然保护区（１５种）。随着片断与自然保护区的距离增加,片断与保护区共有物种数减少（从５种、３种至２种）;最重要     

中国自然保护地体系分类研究

建设自然保护地体系是为子孙后代保留生物多样性资源与自然遗产最有效的途径。自1956年我国建立第一个自然保护区以来,已建设形成覆盖森林、草地、湿地、海洋、荒漠各类生态系统,珍稀濒危动植物物种和种质资源,自然遗迹和自然景观,以及水源保护等各类自然保护地。但由于缺乏自然保护地体系的顶层设计,各类保护地面临功能区分不清晰、空间重叠、管理成效不高等问题。建设以国家公园为主体的自然保护地体系的部署,为理顺我国保护地体系,明确各类保护地的功能定位提供了难得的机会。在分析我国现有自然保护地类型,并参考国际自然保护地体系分类经验的基础上,探讨了我国保护地体系分类,建议将我国自然保护地分为5大类,第I类为自然保护区,第Ⅱ类为国家公园,第Ⅲ类为自然公园,第Ⅳ类为物种与种质资源保护区,第Ⅴ类为生态功能保护区,并分析了各类自然保护地的功能定位和管理目标,以期为自然保护地体系规划建设提供参考。完善我国自然保护地体系分类,根据各类保护地的特点,创新保护地建设政策与机制,加大政府对自然保护地建设力度的同时,发挥全社会力量建设自然保护地,我国自然保护地建设将大有可为。     

广西邦亮长臂猿自然保护区的鸟类

摘要：于2006年5月及2010年的1月、5月和9～ 10月,采用样线法和定点观察法,结合雾网法对邦亮自然保护区鸟类资源进行了调查。共记录到鸟类223种,隶属于14目49科,其中留鸟146种、夏候鸟40种、冬候鸟34种、旅鸟3种。区系分析表明,保护区鸟类具有典型的华南区区系特点和显著的北热带特征。保护区有国家Ⅱ级重点保...     

Kobresia tibetica tussocks facilitate plant species inside them and increase diversity and reproduction

Many plant species grow inside tussocks of some graminoids, but the underlying mechanisms remain unclear. We address whether some species occur and flower mainly inside tussocks so that species diversity and sexual reproduction are higher inside than outside tussocks, and whether relieving biological and physical stress is the mechanism associated with the facilitative process. In a heavily grazed grassland on the eastern Tibetan Plateau, where both physical (due to high altitude) and biological conditions (due to heavy grazing) are extremely harsh, we investigated vegetation in paired plots inside and outside 150 Kobresia tibetica tussocks and measured tussock basal area (=plot area). We also measured temperatures at soil surface, 5 and 10 cm depth and the number of animals (yaks, sheep and horses) grazing inside and outside tussocks. Sixty-seven percent of the species occurred and 42% flowered more frequently inside than outside tussocks, but none less frequently. Inside tussocks 78% species flowered, but outside tussocks only 31% did. Consequently, number of species, number of flowering species and number of inflorescences were all markedly larger inside than outside tussocks. Differences in number of species, number of flowering species and number of inflorescences inside and outside tussocks increased with increasing tussock basal area. Soil temperatures were lower inside than outside tussocks, but grazing intensity was much larger outside tussocks. Therefore, tussocks of K. tibetica facilitated the species inside them likely by grazing prevention, but not by increasing warmth. This study provides evidence that plant species colonizing tussocks of graminoids can be facilitated by the tussock species, and facilitation by grazing prevention may be one mechanism causing the coexistence of the species inside tussocks.     

Seed bank dynamics in abandoned meadows during a 20-year period in the Białowieża National Park

1 The relationship between size and floristic composition of the seed bank and vegetation dynamics was studied between 1976 and 1996 in 0.75 ha of an abandoned Cirsietum rivularis meadow. The plot was divided into 100-m² (10 × 10 m) quadrats and sampled 5-yearly to map the vegetation and determine the soil seed bank.
2 Densities of seeds in the soil fluctuated as succession proceeded. The initially small seed bank trebled by 15 years after abandonment, before falling, after 20 years, to approximately the same as in the initial stage.
3 The floristic richness of the seed bank decreased during succession, with the number of species falling from 38 to 25. The diversity of life forms, however, increased in later periods, with tall herbs, shrubs and trees appearing after 10 years.
4 Seed bank floristic composition is apparently both a product of the species composition of the current vegetation and a record of the long-term substitution of species. Other factors, including the structure of the vegetation, also influence the accumulation of seeds in the soil.
5 Although changes in number of species show a directional pattern, the seed bank size fluctuated in the course of succession on these fertile wet meadows.     

Induction of annual cyclical changes in the ichthyofauna of a large microtidal estuary following an artificial and permanent increase in tidal flow

The opening of a deep artificial and second entrance channel into the large Peel‐Harvey Estuary in south‐western Australia in 1994 provided a unique opportunity to determine the characteristics of the ichthyofauna of a microtidal estuary, in which tidal water movement and the rate of recovery of salinities in spring have both increased markedly. Fishes in the original entrance channel and both halves of the two large basins (Peel Inlet and Harvey Estuary), which constitute most of the total area of the estuary, were sampled using a 21·5 m long seine with a fine (3 mm) mesh bunt. The 72 337 fishes that were caught throughout the estuary and represented 43 species, comprised mainly marine species, both in terms of number of species (65·1%) and number of individuals (70·6%). The number of species and density of fishes in each region, and particularly in the basins, showed a pronounced tendency to decline from a maxima in summer to a minima in winter and then to rise in spring. Although the species composition of the fish fauna in the natural entrance channel differed significantly from that in each of the four basin regions, those within the basins were significantly different only in the cases of the southern Harvey Estuary versus both regions of the Peel Inlet. Species composition in the natural entrance channel and four basin regions each underwent conspicuous cyclical changes during the year, which reflected out‐of‐phase changes in the densities of certain species. Although this cyclical pattern was due mainly to changes in the densities of marine species, it was augmented by those of estuarine residents. The cyclicity, which was not evident prior to the opening of the artificial Dawesville Channel, and thus when tidal water movement within the estuary was far less pronounced, parallels the situation recorded for macrotidal northern hemisphere estuaries.     

Random amplified polymorphic DNA assessment of diversity in western Mediterranean populations of the seagrass Posidonia oceanica

Posidonia oceanica is an endemic Mediterranean seagrass species that has often been assumed to contain low levels of genetic diversity. Random amplified polymorfic DNA (RAPD) markers were used to assess genetic diversity among five populations from three geographical regions (north, central, and south) of the western Mediterranean Sea. Stranded germinating seeds from one of the central populations were also included in the analysis. Forty-one putative genets were identified among 76 ramets based on 28 RAPD markers. Genotypic diversity strongly depended on the spatial structure, age, and maturity of the meadows. The lowest clonal diversity was found in the less structured and youngest prairies. Conversely, a high genotypic diversity was found in the highly structured meadows. The genotypic diversity in these meadows was at the same level as in P. australis and higher than previously reported data for P. oceanica populations in the Tyrrhenian Sea near the coast of Italy.