The gorgonian coral Acabaria biserialis: life history of a successful colonizer of artificial substrata

The azooxanthellate coral Acabaria biserialis Kükenthal, 1908 (Octocorallia: Alcyonacea) is highly abundant on the vertical underwater structures of the oil jetties at Eilat (Red Sea), but it is rare on the adjacent natural reefs. To understand its success on such artificial substrata we examined various aspects of its life history and population dynamics. A. biserialis is a gonochoric brooder. The percentage of colonies on the artificial substrata bearing gonads ranged from none (September 1994 and 1995) to 100% (January 1994, 1995 and April 1994). Mature oocytes and sperm sacs reached rather small maximum diameters of 240 and 160 μm, respectively, probably dictated by the small gastrovascular cavities. A continuous release of planulae was observed in the laboratory from March to July 1995. Planulation occurred during various lunar phases, and both by day and night. Recruitment of A. biserialis on PVC plates attached to the jetties coincided with the breeding period inferred from the laboratory findings. Recruits reached a maximum height of 3 cm within 3 months, thus exhibiting a remarkably rapid growth rate compared with other gorgonians. This high colony growth rate may compensate for the lack of clonal propagation in the studied A. biserialis population. The complex substrata of the jetties provide the conditions required for successful colonization, which include upside-down orientation, an adequate light regime and exposure to flow. The findings of our study may provide a useful contribution to the design of artificial reefs aimed at attracting rapid colonization by A. biserialis colonies. Received: 30 December 1998 / Accepted: 19 August 1999     

DNA fingerprints of a gorgonian coral: a method for detecting clonal structure in a vegetative species

Clonal reproduction, a common life history strategy among sessile marine invertebrates, can lead to high local abundances of one to a few genotypes in a population. Analysis of the clonal structure of such populations can provide insight into the ecological and evolutionary history of the population, but requires markers that can identify individual genets. Forensic and demographic studies have demonstrated that DNA fingerprinting can provide markers that are unique for an individual genotype. We have generated DNA fingerprints for over 70 colonies of the clonal gorgonian, Plexaura A (Plexaura sp. A) collected from June 1990 through July 1991 in the San Blas Islands, Panama. DNA fingerprints within a singic individual were identical and fingerprinting resolved multiple genotypes within and among reefs. On one reef in the San Blas Islands, Panama, 59% of the colonies sampled were of one genotype and this genotype was not found on any other sampled reefs. A previous study using tissue grafts identified 13 putative clones on these reefs, while DNA fingerprints of the same colonies differentiated 17 genotypes. The present study demonstrates the utility of DNA fingerprinting for distinguishing clones and for identifying clonal structure of marine invertebrate populations.     

Movements between coral colonies in Trapezia ferruginea (Crustacea: Brachyura), an obligate symbiont of scleractinian corals

Trapezia ferruginea appears to depend entirely on its coral host (Pocillopora spp.) for shelter and food. Field and laboratory experiments have shown that the brightly colored crabs move between colonies at night. Analysis of movements in crabs randomly distributed among randomized Pocillopora damicornis colonies under laboratory conditions showed that after 6 days there was a significant increase in the number of heterosexual pairs (P<0.001) and a significant correlation between the number of crabs and the size of colonies (P=0.003), as well as between the size of crabs and the size of colonies (P=0.020) — conditions which are also observed in the field. No such correlations were obtained (P>0.05) in a similar experiment where very intense predation by carnivorous fishes was present. This host selection by adults appears to be elicited by the lack of a suitable partner and the inadequate size of their established territory in the colony.     

Multivariate analysis of spatial patterns: a unified approach to local and global structures

We propose a new approach to the multivariate analysis of data sets with known sampling site spatial positions. A between-sites neighbouring relationship must be derived from site positions and this relationship is introduced into the multivariate analyses through neighbouring weights (number of neighbours at each site) and through the matrix of the neighbouring graph. Eigenvector analysis methods (e.g. principal component analysis, correspondence analysis) can then be used to detect total, local and global structures. The introduction of the D-centring (centring with respect to the neighbouring weights) allows us to write a total variance decomposition into local and global components, and to propose a unified view of several methods. After a brief review of the matrix approach to this problem, we present the results obtained on both simulated and real data sets, showing how spatial structure can be detected and analysed. Freely available computer programs to perform computations and graphical displays are proposed.     

Participatory monitoring to connect local and global priorities for forest restoration

New global initiatives to restore forest landscapes present an unparalleled opportunity to reverse deforestation and forest degradation. Participatory monitoring could play a crucial role in providing accountability, generating local buy in, and catalyzing learning in monitoring systems that need scalability and adaptability to a range of local sites. We synthesized current knowledge from literature searches and interviews to provide lessons for the development of a scalable, multisite participatory monitoring system. Studies show that local people can collect accurate data on forest change, drivers of change, threats to reforestation, and biophysical and socioeconomic impacts that remote sensing cannot. They can do this at one‐third the cost of professionals. Successful participatory monitoring systems collect information on a few simple indicators, respond to local priorities, provide appropriate incentives for participation, and catalyze learning and decision making based on frequent analyses and multilevel interactions with other stakeholders. Participatory monitoring could provide a framework for linking global, national, and local needs, aspirations, and capacities for forest restoration.     

Linking marine predator diving behavior to local prey fields in contrasting habitats in a subarctic glacial fjord

Foraging theory predicts that animals will adjust their foraging behavior in order to maximize net energy intake and that trade-offs may exist that can influence their behavior. Although substantial advances have been made with respect to the foraging ecology of large marine predators, there is still a limited understanding of how predators respond to temporal and spatial variability in prey resources, primarily due to a lack of empirical studies that quantify foraging and diving behavior concurrently with characteristics of prey fields. Such information is important because changes in prey availability can influence the foraging success and ultimately fitness of marine predators. We assessed the diving behavior of juvenile female harbor seals (Phoca vitulina richardii) and prey fields near glacial ice and terrestrial haulout sites in Glacier Bay (58°40′N, ?136°05′W), Alaska. Harbor seals captured at glacial ice sites dived deeper, had longer dive durations, lower percent bottom time, and generally traveled further to forage. The increased diving effort for seals from the glacial ice site corresponded to lower prey densities and prey at deeper depths at the glacial ice site. In contrast, seals captured at terrestrial sites dived shallower, had shorter dive durations, higher percent bottom time, and traveled shorter distances to access foraging areas with much higher prey densities at shallower depths. The increased diving effort for seals from glacial ice sites suggests that the lower relative availability of prey may be offset by other factors, such as the stability of the glacial ice as a resting platform and as a refuge from predation. We provide evidence of differences in prey accessibility for seals associated with glacial ice and terrestrial habitats and suggest that seals may balance trade-offs between the costs and benefits of using these habitats.     

Sex ratios in bumble bee colonies: Complications due to orphaning?

Summary Highly male-biased investment ratios (1:2.86, F:M, biomass wet weight) were found among reproductives reared by 32 Bombus terricola colonies set out in the field and 35 B. melanopygus colonies held in laboratory confinement. The numerical sex ratios were almost identical for the two species (1 queen to 6.1 males). Most of the males were produced early in the season by small weak colonies. It is argued that in a population where some colonies are orphaned and rear only males, female-biased sex ratios are expected among the surviving queen-producing colonies.     

Temporal and spatial variability in coral recruitment on two Indonesian coral reefs: consistently lower recruitment to a degraded reef

Corals are the primary reef-building organisms, therefore it is key to understand their recruitment patterns for effective reef management. Coral recruitment rates and juvenile coral abundance were recorded in the Wakatobi National Marine Park, Indonesia, on two reefs (Sampela and Hoga) with different levels of environmental degradation (12.5 vs. 44 % coral cover with high and low sedimentation rates, respectively) to examine consistencies in recruitment patterns between years and seasons. Recruitment was measured on multiple panels at two sites on each reef (6–7 m depth) and cleared areas of natural reef. Although coral recruitment was twofold higher in 2008–2009 than in 2007–2008, and seasonal differences were identified, consistent significant differences in recruitment rates were found between the two reefs even though they are separated by only ~1.5 km. Recruitment rates and juvenile abundance were lower on the more degraded reef. These patterns are likely a consequence of differential pre- and post-settlement mortality as a result of the high sedimentation rates and degraded conditions and possibly reduced larval supply.     

Molecular evidence for multiple lineages in the gorgonian family Plexauridae (Anthozoa: Octocorallia)

Octocorals are diverse and abundant on many marine hard substrates, and, within this group, members of the family Plexauridae are an important component of tropical reef assemblages, especially in the Caribbean. To understand historical relationships within this large and diverse assemblage, and to test the monophyly of the family and some of its genera, DNA sequences of two mitochondrial loci (msh1 and ND2, ~1,185 bp) were analyzed from 46 species in 21 genera from deep and shallow waters in the tropical western Atlantic and in the tropical western and eastern Pacific (plus 9 taxa in the closely related Gorgoniidae and 1 species of the more distantly related Alcyoniidae). Five strongly supported clades were recovered. Three large clades correspond roughly to the Plexauridae, Paramuriceidae, and Gorgoniidae, and two smaller clades were comprised of taxa previously assigned to several families. Astrogorgia sp. did not group with any of the clades. The mutual relationships among the five clades remain unclear. Several genera previously regarded as unrelated appear to be grouped among the three families; e.g. Hypnogorgia sp. (Paramuriceidae) falls within a clade consisting of both Pacific and Atlantic Muricea spp. (Plexauridae), while Swiftia sp., Scleracis sp., and an Atlantic Thesea sp. (all Paramuriceidae) group with the gorgoniids. In several instances, genera containing Atlantic and Pacific species were recovered as monophyletic (Muricea spp., Bebryce spp.). However, in at least three cases (Echinomuricea spp., Thesea spp., Villogorgia spp.), placement of Atlantic and Pacific species in the same genus may reflect convergence of sclerite morphology. The results indicate a strong need for reexamination of octocoral taxonomy using a combination of molecular, morphological, and chemical evidence.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-005-1592-y.Communicated by J.P. Grassle, New Brunswick     

Seasonality and dynamics in coral reef macroalgae: variation in condition and susceptibility to herbivory

Seasonal variation in coral reef macroalgal size and condition is well documented, yet seasonal variability of herbivory on macroalgae by coral reef fishes is unknown. Herbivore feeding intensity was quantified monthly on an inner-shelf reef on the Great Barrier Reef, using Sargassum bioassays. Removal rates of transplants displayed high levels of variation with significantly higher rates of removal during the summer months. Differences in Sargassum plant size and condition suggest that the variability in herbivore feeding intensity is attributed primarily to the variation in the condition of the macroalgae, especially epiphyte loads. The dramatic changes in macroalgal removal reveal a considerable decrease in herbivore activity in the winter. This highlights the clear distinction between ‘summer’ and ‘winter’ months in terms of reef processes, emphasizing the high seasonal variation in macroalgal removal rates at different time of the year.     

Linking Wild and Captive Populations to Maximize Species Persistence: Optimal Translocation Strategies

Abstract:  Captive breeding of animals is widely used to manage endangered species, frequently with the ambition of future reintroduction into the wild. Because this conservation measure is very expensive, we need to optimize decisions, such as when to capture wild animals or release captive-bred individuals into the wild. It is unlikely that one particular strategy will always work best; instead, we expect the best decision to depend on the number of individuals in the wild and in captivity. We constructed a first-order Markov-chain population model for two populations, one captive and one wild, and we used stochastic dynamic programming to identify optimal state-dependent strategies. The model recommends unique sequences of optimal management actions over several years. A robust rule of thumb for species that can increase faster in captivity than in the wild is to capture the entire wild population whenever the wild population is below a threshold size of 20 females. This rule applies even if the wild population is growing and under a broad range of different parameter values. Once a captive population is established, it should be maintained as a safety net and animals should be released only if the captive population is close to its carrying capacity. We illustrate the utility of this model by applying it to the Arabian oryx ( Oryx leucoryx ). The threshold for capturing the entire Arabian oryx population in the wild is 36 females, and captive-bred individuals should not be released before the captive facilities are at least 85% full.     

An equilibrium theory of queen production in honeybee colonies preparing to swarm

Summary An equilibrium model is developed which seeks to explain the regulation of queen rearing in honeybee colonies preparing to swarm. The model postulates that there is a balance between nurse bees becoming inhibited from queen rearing and nurses losing their inhibition, and that whether a colony does or does not rear queens reflects the equilibrium percentage of inhibited nurses. This model leads to a quantitative prediction about the size of a conoly's nurse population at which queen rearing should start. Comparing the model's predictions with empirical observations pinpoints data needed for a more complete explanation of control of queen rearing. In particular, the model suggests a central regulatory role for density-dependent changes in the behaviors involved in queen substance dispersal.     

Genotypic differences in brood rearing in honey bee colonies: context-specific?

Summary Three experiments were performed to determine whether brood care in honey bee colonies is influenced by colony genetic structure and by social context. In experiment 1, there were significant genotypic biases in the relative likelihood of rearing queens or workers, based on observations of individually labeled workers of known age belonging to two visually distinguishable subfamilies. In experiment 2, no genotypic biases in the relative likelihood of rearing drones or workers was detected, in the same colonies that were used in experiment 1. In experiment 3, there again were significant genotypic differences in the likelihood of rearing queens or workers, based on electrophoretic analyses of workers from a set of colonies with allozyme subfamily markers. There also was an overall significant trend for colonies to show greater subfamily differences in queen rearing when the queens were sisters (half- and super-sisters) rather than unrelated, but these differences were not consistent from trial to trial for some colonies. Results of experiments 1 and 3 demonstrate genotypic differences in queen rearing, which has been reported previously based on more limited behavioral observations. Results from all three experiments suggest that genotypic differences in brood care are influenced by social context and may be more pronounced when workers have a theoretical opportunity to practice nepotism. Finally, we failed to detect persistent interindividual differences in bees from either subfamily in the tendency to rear queen brood, using two different statistical tests. This indicates that the probability of queen rearing was influenced by genotypic differences but not by the effect of prior queen-rearing experience. These results suggest that subfamilies within a colony can specialize on a particular task, such as queen rearing, without individual workers performing that task for extended periods of time.     

Innovative substrate tiles to spatially control larval settlement in coral culture

We designed settlement tiles for coral culture with the aims: (1) to attract and (2) to spatially control settlement and (3) to produce substrate units for further handling in mariculture. Ceramic tiles with vertical (i.e. pyramid tile; truncated pyramid shape, 22.0×22.0, ±1.0 mm, L×W) and horizontal surfaces (i.e. flat tile; 17.0×17.0, ±1.0 mm, L×W) were temporarily arranged chessboard-like in a polystyrene grid. Surfaces of both types were structured with grooves (width and depth 2.0±0.1 mm). Material analysis by ICP and photospectrometry showed negative influences on water chemistry when new tiles were directly used; high contents of heavy metals could be detected depending on the production process. Planulae of Acropora tenuis (16.3±3.1% settlement) preferred to settle in the grooves of pyramid tiles with a density of 0.19±0.03 to 0.44±0.06 settlers cm^–2, whereas those of Favia fragum (60.7±13.3% settlement) showed high preferences for the grooves of flat tiles (0.48±0.22 to 1.05±0.44 settlers cm^–2). Settlement occurred exclusively on surfaces with a biofilm (turf and crustose coralline algae) and was independent of available substrate surface area, whereas the number of tiles per set-up influenced the density of settlers per unit. Spatial control of settlement was achieved through tile design and arrangement. Tiles with settlers could be easily separated for further use in coral culture.Communicated by O. Kinne, Oldendorf/Luhe     

Microplastics in mangroves and coral reef ecosystems: a review

Microplastic pollution has recently been identified as a major issue for the health of ecosystems. Microplastics have typically sizes of less than 5 mm and occur in various forms, such as pellets, fibres, fragments, films, and granules. Mangroves and coral reefs are sensitive and restricted ecosystems that provide free ecological services such as coastal protection, maintaining natural cycles, hotspots of biodiversity and economically valuable goods. However, urbanization and industrial activities have started contaminating even these preserved ecosystems. Here we review sources, occurrence, and toxicity of microplastics in the trophic levels of mangrove and coral reef ecosystems. We present detection methods, such as microscopic identification and spectroscopy. We discuss mitigating measures that prevent the entry of microplastics into the marine environment.