Will future climate change threaten a range restricted endemic species, the quokka (Setonix brachyurus), in south west Australia?

Range-restricted species, such as regional endemics, possess traits that may make them particularly vulnerable to environmental change. The quokka, Setonix brachyurus, is a small macropod, endemic to south-western Australia and two adjacent islands. Climatic factors appear to play a role in defining the distribution of this species. Mainland populations are historically restricted to areas with an annual average rainfall in excess of 700 mm and their current distribution is almost completely confined within the 1000 mm rainfall isohyet. As such, the predicted increasing aridity of south-western Australia due to climate change is likely to threaten the continued persistence of the quokka on the mainland. To examine this possibility, we modelled the distribution of the quokka with Maxent using records of occurrence and a combination of historical climate (1961-1990) and habitat variables. Future projections of this distribution were then examined assuming two simple dispersal scenarios (zero and full migration) and three climate-change scenarios of increasing severity for 2030, 2050 and 2070. The predictive performance of the distribution model generated under historical climate conditions was high (AUC > 0.8), with annual precipitation contributing the most information to the model. Except for the low-severity climate-change scenario under the full dispersal assumption, the future projected distribution of quokka was shown to contract over time. The extent of range contraction tended to increase with the severity of the climate-change scenario, with the species predicted to lose almost all range by the year 2070 under the most extreme climate-change scenario. The results indicate the importance of identifying potential refuges for the quokka (i.e. areas where the species is predicted to persist) and defining management strategies to protect these areas from threatening processes.     

Influence of forest fragmentation on an endangered large-bodied lemur in northwestern Madagascar

Madagascar’s diverse and mostly endemic fauna and flora suffer from recent landscape changes that are primarily caused by high levels of human activities. The loss and fragmentation of forest habitats are well known consequences of human activities. In this study, we investigate the effects of forest fragmentation on presence, abundance and genetic diversity in a larger-bodied lemur species, Lepilemur edwardsi, in northwestern Madagascar. In addition, we characterized the genetic differentiation among populations and demographic changes. We found L. edwardsi at only 13 (76.5%) of 17 visited sites, 11 of which were situated in the Ankarafantsika National Park (ANP). We captured between two and 17 individuals per site. We sequenced the mtDNA d-loop of all samples and genotyped 14 microsatellite loci in two exemplary populations for demographic analyses. A negative influence on forest fragmentation could be detected, since the fragments had a lower genetic diversity than sites in the ANP. Genetic differentiation between populations ranged from low to high but was almost always significant. A typical pattern of isolation-by-distance could not be detected and the data could rather be interpreted as results of random genetic drift. The data furthermore revealed signals of a demographic collapse of about two orders of magnitude in the two exemplary sites. This decline probably started during the last few hundred years of intensified human disturbances and population growth. Given the results of this study, urgent conservation actions are needed and should concentrate on an effective protection of the few remaining populations in order to ensure the long-term survival of L. edwardsi.     

Origin of cultivated Tatary buckwheat (Fagopyrum tataricum Gaertn.) revealed by RAPD analyses

The phylogenetic relationships among cultivated landraces and natural populations of wild subspecies of Tatary buckwheat were investigated at the individual level by constructing a phylogenetic tree based on RAPD markers. As the PCR templates, DNA of individuals rather than bulked samples, was used. Ten individuals from 10 cultivated landraces, 71 individuals from 21 natural populations of wild subspecies, and 7 individuals from 3 weedy Tatary buckwheat were provided for RAPD analyses. Three groups were recognized: (1) all cultivated landraces and wild subspecies from central Tibet and northern Pakistan; (2) 10 individuals of wild subspecies from northwestern Yunnan; (3) the remaining individuals of wild subspecies from northwestern Yunnan and all individuals of wild subspecies from Sichuan. Group (2) was phylogenetically closely related to group (1). The origin of cultivated Tatary buckwheat, the hybrid origin of weedy Tatary buckwheat and of the wild populations from central Tibet and northern Pakistan are discussed. We arrive at the conclusion that cultivated Tatary buckwheat probably originated in northwestern Yunnan in China.     

Does reproductive plasticity in Lumbricus rubellus improve the recovery of populations in frequently inundated river floodplains?

Flooding events often eradicate all of the individuals of the earthworm species Lumbricus rubellus living in river floodplains, although earthworm cocoons usually survive immersion, permitting populations to recover after the flood waters recede. Yet, if the area is flooded again before earthworms hatching from cocoons or migrating from adjacent areas reach reproductive maturity, it is unlikely that their populations will recover. The objective of this study is to determine the importance of the length of the dry period for population recovery in L. rubellus. Earthworms were collected at three floodplain sites along the Rhine River that were frequently, moderately or seldom flooded. Reproductively mature L. rubellus from the frequent flooded site were half the weight and probably younger than those from the other sites. A mechanistic population model was used to estimate the time for earthworm development from hatching to reproductive maturity, and to calculate the probability of population recovery after flooding. The model results show that the probability of extinction increases when the dry period is not long enough for individuals to reach reproductive maturity. When this condition is met population extinction is virtually absent resulting from the high lifetime reproductive output of L. rubellus. Parameterization of the model with site-specific data indicate that population survival on the site with the shortest dry period drastically decreases if worms mature at the weight measured at the other sites. The results therefore strongly suggest that the dry period is critical for population recovery in river floodplains and that earthworm populations have adapted to local (site-specific) conditions.     

应用RAPD分析川西北高原老芒麦自然居群的遗传多样性

利用RAPD标记对来自青藏高原东南部川西北高原的8个老芒麦自然居群的遗传多样性和群体遗传结构进行了分析和评价。从150个RAPD引物中筛选出25个能扩增出高度重复性条带的引物。这25个引物共扩增出370条可分辨的条带,其中291条(占78.65%) 具有多态性,表明供试居群在物种水平上存在较高水平的变异。同时各居群的多态性位点比率(PP)在46.49%到53.78%之间变化,表明群体水平的变异较低。居群的平均基因多样性(HE)为0.176(变幅为0.159~0.190),而物种水平的平均基因多样性达0.264。基于Nei’s基因多样性、Shannon指数和贝叶斯方法的群体分化系数分别为32.0%、33.7%和33.5%。AMOVA 分析表明居群内遗传达到总变异的59.9%,而居群间变异仅有40.1%,但二者均达到极显著水平(P < 0.001)。居群间每世代迁入个体数(Nm)达到0.503个。各居群间存在较高的Nei’s遗传一致度。本研究获得的老芒麦的遗传结构不同于已报导的大多数披碱草属物种。另外,基于聚类分析及AMOVA的结果均表明各居群间存在较为明显的地理分化,8个居群分化为采集地的南部和北部2个分支。总之,研究结果表明来自青藏高原东南部的老芒麦居群具有较高水平的遗传变异。在该地区应尽量选择遗传多样性高的老芒麦居群实施就地保护。     

Two genetically distinct units of the Chinese sika deer (cervus nippon): analyses of mitochondrial DNA variation

Chinese sika deer, Cervus nippon, are currently threatened by habitat loss, fragmentation and human hunting, which has led to the extinction of three subspecies in the wild. The remaining subspecies subsist in the narrow regions of Jilin, Heilongjiang, Sichuan, Gansu, Jiangxi, Anhui, and Zhejiang provinces. In order to design effective conservation strategies for the Chinese sika deer, we have investigated genetic diversity, population structure and gene flow in the Chinese sika deer populations by analyzing ≈995 base pairs of the mitochondrial DNA (mtDNA) control region in 59 individuals sampled from the northeast of China, Sichuan, Jiangxi and Zhejiang. Chinese sika deer exhibited low mtDNA diversity and high gene flow among the four populations, and showed no strong geographical structure. The analyses of mtDNA variation among individuals of sika deer identified only two main phylogenetic groups even though three subspecies were sampled. These data singles out the Zhejiang population as being highly genetically distinct and worthy of separate conservation consideration. Therefore, it is recommended that a breeding program for the Zhejiang population be established.     

Abundance, body size and movement patterns of a tropical treefrog in continuous and fragmented forests in the Brazilian Amazon

Phyllomedusa tarsius is a hylid frog that breeds in ponds located in a range of habitats from continuous forests to severely disturbed matrix habitats in Central Amazon. During three reproductive seasons, we followed the movement patterns, measured body size and registered abundance and residency time of this species in five habitats: pasture, Vismia regrowth, Cecropia regrowth, 1 and 10 ha forest fragments, and continuous forest. The frog captures were strongly correlated with rainfall in all disturbed habitats, but not in continuous forest, probably because individuals respond more directly to rainfall patterns in more open habitats. Males in disturbed habitats were smaller than those found in continuous forest, perhaps as a result of differences in habitat quality. Males remained at sites for longer periods in fragments and continuous forest compared to matrix habitats. Here again, the quality and suitability of breeding sites in matrix habitats may be lower than in continuous forest resulting in the need for more movement. We found bigger subpopulations in matrix habitat ponds and a higher percentage of individuals moving among them when compared to continuous forest ponds. Constant movement of individuals among disturbed subpopulations decreases population isolation and increases interbreeding among different subpopulations. No movement between individuals from continuous forest ponds and disturbed habitats was observed. This suggests that the disturbed habitat subpopulations are not acting as sink subpopulations for continuous forest populations. The maintenance of individuals in fragments is more dependent on local conditions for reproduction and on subpopulations in the matrix habitat than on recruitment of individuals from populations in continuous forest.     

Discovery of c-SNPs in Anemone coronaria L. and Assessment of Genetic Variation

Single nucleotide polymorphisms (SNPs) were discovered in 44 cDNA clones from leaves by comparison of the commercial cultivar ‘Mona Lisa‘ with a wild population of Anemone coronaria L. One hundred and fifty five SNPs were discovered with an average frequency of one SNP per 167 bp. Forty nine percent of the SNPs are transitions, 43 are transversions, 26 are heterozygotes and 9% are InDels. Eighty two (68%) of the SNPs located in the ORF, resulted in a change of amino acid while 39 (32%) did not affect the amino acid. Thirty eight SNPs (46%), which change the amino acid, resulted in similar amino acid, while 44 SNPs (54%) resulted in a non-similar amino acid. Nine polymorphic sites were genotyped by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) using genomic DNA. Phylogenetic analysis of 50 individuals from six wild populations and the commercial cultivar revealed high polymorphism within and low polymorphism between A. coronaria L. wild populations. The phylogenetic tree revealed only one clear cluster of the ‘Mona Lisa’ cultivar. All the other individuals from the various wild populations are distributed on different nodes indicating that the genetic variation within the wild populations is high while the commercial cultivar is quite homogenous and genetically different from all other populations.     

Fruiting failure and limited recruitment in remnant populations of the hawkmoth-pollinated tree Oxyanthus pyriformis subsp. pyriformis (Rubiaceae)

Plants with highly specialized pollination systems may be particularly vulnerable to the effects of habitat fragmentation. The sub-canopy tree Oxyanthus pyriformis subsp. pyriformis has deep tubular flowers (c. 90 mm in length) that are specialized for pollination by long-tongued hawkmoths. Existing natural populations of this taxon appear to be confined to two suburban habitat fragments in the city of Durban, South Africa. Breeding system experiments showed that the trees are self-incompatible and thus completely reliant on pollen vectors for sexual reproduction. Hawkmoths were rarely observed to visit flowers, despite intensive monitoring over four seasons from 1997 to 2003. Fruit set as determined from examination of more than 150,000 flowers at the two sites was extremely low (0.04% and 0.07% of flowers), but increased to more than 70% in flowers that were hand-pollinated with pollen from another tree. This >1000-fold increase in the likelihood of fruit production following pollen-supplementation indicates that trees experience severe pollen-limitation of fruit set. Natural fruit set is so low that only a few dozen fruits were recorded in each population during two years of monitoring. This is of concern as O. pyriformis trees are dependent solely on seeds for recruitment. Demographic surveys showed that remaining natural populations have fewer saplings than adult trees and only two seedlings for every adult tree. The long-term viability of reintroduced populations of O. pyriformis is also in doubt, as we observed an almost complete lack of recruitment in a population that was established in a seemingly suitable forest site 20 years ago. Regular hand-pollination and, in some instances, further planting of saplings, may be the only way to safeguard these populations.     

Interaction between tolerance and 70 kDa stress protein (hsp70) induction in collembolan populations exposed to long-term metal pollution

Induction of the 70 kDa stress proteins (hsp70) as a marker for cellular stress response was investigated in two species of Collembola from a metal concentration gradient near a brass mill in the vicinity of Gusum, Sweden. In the field, populations of Orchesella bifasciata (Nicolet 1841) in the middle of the gradient, which ranged from about 60 to 3800 mg of Zn+Cu per kg dry wt. litter, had 40% higher hsp70 levels than populations from the least and most contaminated sites, but differences were not significant. All but one of the populations, inhabiting a severely polluted area, approached lower hsp70 values when they were fed algae containing very high metal concentrations; the hsp70 level in specimens from the control site exposed to polluted algae was below the detection limit, most probably due to pathological cell damage. The hsp70 levels in specimens from contaminated sites with the highest in situ hsp70 levels could not be distinguished from those of control site individuals after they were reared on litter from the control site, and the hsp70 level of control site individuals increased by nearly 100% when they were reared on litter from one of the contaminated sites. Tomocerus flavescens (Tullberg 1871) had higher hsp70 levels than O. bifasciata at the contaminated sites but responded similarly to the experimental treatments. A model is presented to interpret the observations as the result of the dual role of hsp70 to maintain cellular protein homeostasis and to stabilise protein folding in metal tolerant specimens. Differences in tolerance between individuals and heterogeneous distribution of metals in the litter may account for the large intraspecific variability found in hsp70 levels.     

Genetic diversity and structure of natural and agronomic switchgrass (Panicum virgatum L.) populations

Panicum virgatum L. (switchgrass) is an obligate outcrossing C₄ perennial prairie grass currently being pursued for the production of lignocellulosic ethanol. Commercial production of switchgrass for bioenergy has increased substantially in the United States. Understanding the degree of native genetic diversity within and among switchgrass populations will facilitate effective germplasm improvement, conservation, and management programs. In this study, the genetic diversity and differentiation among natural and agronomic switchgrass populations were analyzed at the molecular level by using random amplified polymorphic (RAPD) DNA markers. The mean genetic diversity among populations ranged from 0.051 ± 0.136 to 0.243 ± 0.214 and the mean genetic similarity among all the switchgrass populations was 0.775. The clustering pattern of switchgrass populations grouped the individuals based on their sites of origin, with agronomic cultivars predominantly separated into distinct clusters. The grouping of individuals within and across the populations was corroborated by principal component analysis. These results are consistent with previous reports for switchgrass accessions. RAPD DNA markers were suitable for quickly estimating the genetic diversity of native and agronomic switchgrass populations, and suggest that introgression of agronomic genes into natural switchgrass populations and subsequent changes in genetic structure may be detectable.     

The effect of removal by trapping on body condition in populations of signal crayfish

Crayfish are amongst the most frequently introduced non-native aquatic organisms, with well-documented negative effects on a large number of freshwater taxa. Crayfish-control attempts often make use of manual removal by trapping, a method known preferentially to remove the largest individuals. Studies from aquaculture suggest that lowered population densities and the preferential removal of large individuals may result in non-removed individuals demonstrating increased growth rates. We test the hypothesis under wild conditions, that removal by trapping of American signal crayfish from a UK river would result in an improvement in body condition in the remaining crayfish. We studied four 100 m stretches of two rivers, the Evenlode and Thame, comprising two removal and two non-removal stretches. Each river supported both treatments. Half of the crayfish captured from the removal sections were removed and humanely destroyed by freezing. All crayfish captured from the non-removal sections were marked and returned at the point of capture. Crayfish were more likely to be captured if relatively large and with intact chelae. Catch per unit effort was reduced at the removal sites, and still remained significantly lower between capture sessions. The mean carapace length of crayfish was smaller at removal than non-removal sites. Over the course of the experiment, crayfish at the removal sites became progressively heavier for a given carapace length. The results of this study are consistent with expectations if removals reduced the population density, particularly of large, competitively dominant crayfish, resulting in higher growth rates in the remaining population. This study confirms the possibility that the effects of manual removal by trapping may be at least partially counteracted by density dependent effects improving the body condition of the non-removed portion of the population.     

Genetic structure among earthworms (Lumbricus terrestris L.) from different sampling sites in western Germany based on random amplified polymorphic DNA

Earthworms are being used as bio-indicators to assess terrestrial pollution. However, it is often not known whether their populations possess a uniform genetic structure, which would allow comparison of residues or biological properties of earthworms from different sampling locations. In order to investigate this point, random amplified polymorphic DNA (RAPD) variation was surveyed in earthworms (Lumbricus terrestris) from five different sampling sites in Germany. Forty oligonucleotide RAPD primers (10 base pairs in length) were screened, three of which produced high polymorphic band patterns. A total of 61 DNA fragments were detected in 90 individuals of L. terrestris from five sampling sites with 49 (80.3%) RAPD markers being polymorphic. The genetic similarities within (band sharing rates between 0.756 and 0.795) and among the L. terrestris populations (0.635) were similar even at widely separate locations. Inter-population variation in the RAPD pattern for all five earthworm populations accounted for 37.9% of the total variation, while intra-population variation for three adjacent Saarland populations accounted for only 18.0% of the total variation. Principal component analysis (PCA) and the genetic distances of the populations confirm these results. Twenty-four percent of the genetic distance is caused by geographical isolation as shown by a test for isolation by distance. These results show that L. terrestris fulfils the genetic qualifications for a bio-indicator particularly at closely located sampling sites. However, the results also suggest that earthworm studies of widely separated locations should include genetic characterisation of the earthworm samples.     

Enchytraeid and earthworm communities along a pollution gradient near Olkusz (southern Poland)

The effect of heavy metal pollution on Oligochaeta (Enchytraeidae and Lumbricidae) populations was studied along a pollution gradient in vicinity of Olkusz (southern Poland). The study sites, which differed in metal concentrations in the humus layer, were established in mixed-pine forests 3.5 km, 2.5 km, 3.9 km, 7.9 km and 31.9 km (reference site) from the source of pollution (zinc smelter). Enchytraeid and earthworm population density and species composition were determined from soil sampled four times from the study sites. Enchytraeidae populations consisted of nine genera and 18 species. The dominating enchytraeid species in all study sites was Cognettia sphagnetorum (approx. 90%), except for the most polluted site, where Enchytraeus, Fridericia and Henlea were the most common species diversity and heterogeneity were the highest in the most polluted site. The highest mean densities were found in the reference site (16,333 individuals m^?2) and lowest in the most polluted site (3932 individuals m^?2). Earthworm populations consisted of three epigeic species, and the most abundant one was Dendrobaena octaedra. Earthworms densities in all sites sampled were low. The concentrations of Zn, Pb and Cd in: humus layer, and in enchytraeids and earthworms, were the highest for the most polluted site and decreased with distance from pollution source. Density of Enchytraeidae and body loads of metals in Enchytraeidae and Lumbricidae can be employed for biomonitoring.     

Characterisation of white clover populations collected from the Caucasus and high altitude regions of eastern Turkey

White clover populations collected from the Caucasus region and eastern Turkey were compared with seven white clover cultivars in a moist, lowland, highly fertile environment. The Caucasus collection came from 15 sites below 1000 m and 19 sites above 1000 m; all seven sites in Turkey were above 1000 m. The populations were generally small leaved and except for those from low altitude sites in Dagestan and Azerbaijan populations were acyanogenic. None of the collected populations were significantly higher yielding than Grassland Huia in any season. However, several populations from the Caucasus were higher yielding than Kent Wild White and similar to that of Grassland Tahora. Survival was poor with only four populations having more than 50% of plants surviving after 18 months in this environment. High altitude Caucasus populations were earlier flowering than low altitude populations, an adaptation to allow adequate seed set.There was a negative relationship between altitude of population origin and proportion of cyanogenic plants; and between altitude and both leaf size and canopy height. High incidence of no leaf mark (vv) was associated with populations from colder rather than warmer environments. Populations from sites with low rainfall were larger leaved and more upright than populations from wetter sites. Populations from severely grazed sites were less upright and less cyanogenic than populations from infrequently or nil defoliated sites.Deceased     

Notes on some endangered species of Spanish herpetofauna: I. Podarcis pityusensis Boscá

The status of the populations of Podarcis pityusensis on about 70 islets and small islands around Ibiza and Formentera (Balearic Islands) is examined, using data from our own observations, and, to a lesser amount, other publications. Lizard populations were found on 43 islets, but data are lacking for another 13. Only 10 sites (18%) have abundant and well-maintained populations. In 13 localities (23%), there is no geographic isolation between the populations, or this isolation is very poor and incomplete. The high probability of populations mixing, or actual observation of this mixing, in 19 islands (34%) is indicated. Human pressure on lizard populations is strong in 14 cases (25%). And finally, 18 populations (about one third) may be considered highly endangered or already extinct by elimination or genetic mixing with other populations. Among the subspecies which became extinct through mixing are P.p. miguelensis, P.p. subformenterae, P.p. algae, P.p. sabinae and P.p. grueni. The need for adequate protective measures aimed at the conservation of the remaining populations is emphasized.     

RAPD variation in a germplasm collection of Myracrodruon urundeuva (Anacardiaceae), an endangered tropical tree: Recommendations for conservation

RAPD markers were used to investigate the distribution of genetic variability in a germplasm collection of the dioecious tropical tree Aroeira (Myracrodruon urundeuva) composed of open pollinated maternal half-sib families collected from trees at least 300 meters apart and grouped in nine collection areas throughout its geographical range in Brazil. Open pollinated families from nearby trees from two natural populations were also included in the study. A Principal Coordinate Analysis (PCO) based on genetic similarities estimated with 83 RAPD markers showed no defined clustering among individuals from the same collection areas. However, a matrix correlation test showed low, but significant correlation between genetic and geographic distances (r = 0.17; p < 0.02). An AMOVA showed that 92% of the genetic variation is found within collection areas. Significant variation was found both between regions and between areas within regions although only 3.54 and 4.44% of the variation was found at these levels respectively. An AMOVA on the individuals from the two natural populations resulted in a pattern of distribution congruent to the one found for the collection areas, with 97% of variability within populations. An analysis of 10 open-pollinated half-sib families revealed that between 75% and 89% of the variability is contained within families, suggesting that seeds from one tree represent a significant proportion of the variability found in the population. These results indicate that, either for the establishment of in situ genetic reserves or for ex situ conservation, efforts should be directed to the conservation of several individual trees or collection of open pollinated seed families in a few distant sites. In addition, if resources are available to enlarge the genetic base of the existing collection, expeditions should prioritize collection sites located in areas at significant distances to those already sampled.     

Mercury exposure in humans through food consumption from the Everglades of Florida

In March 1989, The Florida Department of Health and Rehabilitative Services (HRS) issued a Health Advisory recommending the limited consumption of several fish species caught from the Everglades region of South Florida due to elevated methylmercury (MeHg) levels (average 2–3 ppm in fish meat). There were no reports of clinical MeHg poisoning in humans in Florida, although deaths of Florida panthers were attributed to mercury (Hg). poisoning. This study evaluated the extent of MeHg exposure in persons eating contaminated fish in the Everglades region. Populations at risk were identified including sport fishermen, Everglades Residents and subsistence fishermen. Over 1700 individuals were approached; those who had eaten fish or wildlife from the contaminated areas at least once/month for the prior three months were asked to participate. Three hundred and fifty (350) participants completed a brief questionnaire and provided a hair sample for Hg analysis. In 119 (36%) of individuals with levels above the limits of detection, the mean total Hg in hair was 3.62±3.0μg/g [± standard deviation] with a range of 1.28 – 15.57. The most at risk populations identified with respect to Hg levels were Blacks and men. Although the majority of the participants had fished in the Everglades for many years (>15 years), they reported relatively low intake of fish and had low hair Hg levels compared with similar populations in prior studies of other populations at risk. Although 71% of participants knew of the State Health Advisories concerning ingestion of Hg contaminated fish from the Everglades, this did not change their consumption habits. In addition, Blacks, individuals of lower income and of lower education levels were less likely to know about the Health Advisories. Given recent studies of neurologic effects from relatively low in utero MeHg exposure, the continuation of the Mercury Health Advisories and wildlife monitoring in the Everglades are warranted, especially for women of childbearing age and children. However, public education must be targeted for the populations at risk identified in this study in order to reach these populations more effectively.     

Persistence of depleted abalones in marine reserves of central California

We evaluated the persistence and possible recovery of two depleted marine mollusks, the red (Haliotis rufescens) and black abalone (H. cracherodii), in central California, USA. Monitoring over 32-years did not reveal increasing or decreasing trends in red abalone abundances and sizes over the past three decades, in the absence of harvesting. Comparisons between marine reserves protected for at least 25 years and sites with open public access showed significant difference in size structure for black abalone, with individuals greater than 8 cm in shell length comprising 14–37% of animals in reserves and 2–11% at open-access sites, and a trend for greater abundances of red abalone within reserves. Despite no increasing trends, protection in one of the no-take reserves, the Hopkins marine life refuge (HMLR), has led to persistence of red abalone populations over multiple generations, at average densities of 0.2 individuals/m². At other locations, both within the HMLR and elsewhere, red abalone densities are lower than at the location where long-term studies were conducted (av. 0.03 animals/m²), and an order of magnitude lower than for black abalone (av. 0.4 animals/m²). These results suggest that continued fishery closure and protection in no-take reserves are effective tools for allowing persistence of abalone populations, though there are no signs of recovery to levels comparable to those preceding fisheries collapse. Such failure to recover is most likely associated with high natural mortality and possibly continued illegal take, but not with processes underlying low abalone population levels elsewhere, including food or habitat limitation, recruitment failure, or disease. Linking current structure and trends to specific processes is a crucial first step towards devising focused strategies for conserving and re-building depleted marine populations.     

Effectiveness of a small marine reserve in southern China in protecting the harvested sea urchin Anthocidaris crassispina: A mark-and-recapture study

Assessment of the effectiveness of protected areas requires information on population characteristics of the target species. This study used a mark-and-recapture approach to examine the population structure, individual growth, and mortality of the commercially harvested short-spined sea urchin Anthocidaris crassispina in a small (18 ha) no-take marine reserve and two nearby non-protected sites. Sea urchins were tagged with fluorochrome and recaptured 1 year later. The size-at-age relationship was modelled using the Tanaka function, and mortality estimated using an exponential decay function coupled with the Tanaka growth parameters. The urchin population in the reserve consisted of a higher proportion of older individuals than populations in the two non-protected areas, however, large sea urchins (>50 mm) were absent in the reserve. Sea urchins occurring at high densities (>15 ind. m⁻²) in the reserve grew much slower than those outside the reserve, suggesting a density-dependant effect on growth. Growth ring analysis from the rotulae supported the mark-and-recapture results with the maximum number of rings being higher in the reserve than in non-protected sites. Urchins with the same number of growth rings inside the reserve were smaller than those outside the reserve. Within the reserve, urchins with the same number of growth rings were smaller at locations with higher urchin density. Annual mortality rate was lower in the reserve population than in the non-protected populations. These results illustrate the effectiveness of this small reserve in protecting A. crassispina from fishing. However, further study is required to examine whether a high density of small/old individuals is better than a medium density of large individuals in order to maximize the potential spillover of larvae by such small urchin refugia to the surrounding overfished areas.