A comparison of video and point intercept transect methods for monitoring subtropical coral communities

This study evaluated the use of video transects obtained from SCUBA divers or remote operated vehicle (ROV) and point intercept transect (PIT) method from divers for monitoring subtropical coral communities. Comparisons were made between the datasets obtained by the ROV and SCUBA diver video transect (‘Diver’) and the PIT method on three nearby coral sites with different hydrographies, scleractinian coral composition, dominant species and percentage cover. There was no significant difference between the ROV and ‘Diver’ datasets whereas the PIT method tended to over-estimate percentage cover at sites where corals are not extensive. Power analysis showed that the minimum detectable change in coral percentage cover, δ, had low mean values between 0.39% and 1.65% for the ROV dataset, 0.66% for the “Diver’ dataset, and 12.11% for the PIT dataset. This implied that the ROV and SCUBA survey methods can produce higher precision in terms of detecting temporal changes in coral communities and are thus more suitable for scientific research and management purposes than the PIT method. Other advantages of using video transects by SCUBA divers or ROV include provision of permanent records for subsequent studies and public information, less field time incurred and wider survey areas.     

Functional versatility supports coral reef biodiversity

We explore the role of specialization in supporting species coexistence in high-diversity ecosystems. Using a novel ordination-based method to quantify specialist and generalist feeding structures and diets we examined the relationship between morphology and diet in 120 wrasses and parrotfishes from the Great Barrier Reef. We find that wrasses, despite their morphological diversity, exhibit weak links between morphology and diet and that specialist morphologies do not necessarily equate to specialized diets. The dominant pattern shows extensive overlap in morphology (functional morphospace occupation) among trophic groups; fish with a given morphology may have a number of feeding modes. Such trophic versatility may lay the foundation for both the origins and maintenance of high biodiversity on coral reefs.     

Measured coral luminescence as a freshwater proxy: comparison with visual indices and a potential age artefact

Illuminating slices from massive coral skeletons under ultraviolet light can reveal bright luminescent lines in nearshore corals affected by freshwater river flows. The occurrence and intensity of these lines in long-lived corals can then be used to reconstruct past river flow and rainfall, extending the instrumental records of past tropical climate variability considerably. Earlier studies from the Great Barrier Reef, Australia, have used visual assessments of luminescent line intensity to develop semi-quantitative (though potentially subjective) indices of spatial and temporal variations in freshwater flows. Annual visual assessments and relative coral luminescence intensity (measured by fluorescence spectroscopy) and growth variables are first compared for 89 Porites coral colonies from 30 reefs throughout the length and breadth of the GBR. This demonstrates that simple visual assessments can provide useful information, in the absence of quantitative measurements, of this proxy freshwater tracer. The annual range of measured luminescence between the preceding winter minimum and summer maximum, rather than annual average or annual maximum luminescence is shown to be the most robust measure of freshwater flow. Second, from analyses of the coral colony data and over 40-century-long or longer coral core records, attention is drawn to a potential age artefact in annual average and annual maximum measured coral luminescence. These variables show a significant decline through time, similar to the observed decline in average skeletal density. Although the reasons for this decline are unknown, it could compromise interpretation of long-term variations in freshwater flows and subsequent climatic inferences. This artefact does not appear to affect the annual luminescence range which, it is concluded, is a robust proxy for inter-annual variations in river flow and rainfall.     

SedPods: a low-cost coral proxy for measuring net sedimentation

Sediment derived from impaired watersheds is a major stressor to adjacent coral reefs globally. To better understand stresses generated by specific processes and events, many coral reef scientists seek to collect physical samples of settling particles and obtain reproducible information about net rates of sediment accumulation on coral reefs. Yet, the tools most commonly used to gather this information, sediment tube traps, only provide information on the gross accumulation of sediment at a site, in that all particles are effectively trapped within the container, unlike what a coral surface experiences. To address the need for an improved measurement of net particle accumulation on coral surfaces, we propose using recoverable sediment pods (SedPods) that can be constructed from readily available materials for under US $20. These devices are inexpensive, easy to fabricate, and allow for capture of particles over a given time span. The particles can then be used for laboratory analysis and accurate calculation of net accumulation rates on a coral surface proxy. In an experiment in Hanalei Bay, HI, we found that net sediment accumulation on rectangular SedPods was an order of magnitude less than gross accumulation in nearby conventional tube traps.     

Scientific contributions of extensive biodiversity monitoring

To develop a complete and informative biodiversity observation system, it is necessary to compare the strengths and limits of various monitoring schemes. In this article, we examine the various advantages of extensively monitoring fine-grained spatial variations of biodiversity, where the prominent traits of many species within a community (abundance, phenology, etc.) are regularly recorded at numerous sites over a large territory, usually via human observation networks. Linking these variations with environmental factors sheds lights on the major mechanisms leading to changes in biodiversity, thus increasing our knowledge of macroecology and community ecology. This extensive monitoring allows us to assess diffuse effects, contributing to the sound use of the precautionary principle. Combined with site-focused monitoring, information gathered from extensive monitoring provides the raw material necessary to build biodiversity scenarios.     

A new laboratory method for monitoring deep-water coral polyp behaviour

Deep-water corals are found along the oceanic margins world-wide and in the north east Atlantic the most abundant species is Lophelia pertusa (L.). There is now growing evidence that deep-water reefs formed by such species are coming under increasing pressures from resource exploitation, principally deep-sea trawling and hydrocarbon exploration. Here a novel and unobtrusive method of recording deep-water coral behaviour in the laboratory is described using time-lapse video to record silhouettes of the polyps under infrared illumination. The polyps of L. pertusa behaved asynchronously and did not show any clear diurnal patterns over a three-day observation period. Conceptually, sessile benthic suspension feeders appear to be vulnerable to smothering by sediments disturbed by bottom trawls or sub-seabed drilling. This method allows deep-water coral polyp behaviour to be continuously monitored in the laboratory and, therefore, the responses of coral polyps to environmental perturbations such as sedimentation can be recorded. Further work is necessary to resolve the sensitivity of deep-water corals to short-term environmental change and the combined approach of in situ monitoring and subsequent laboratory experimentation has great potential to address these issues.     

Towards the global monitoring of biodiversity change

Governments have set the ambitious target of reducing biodiversity loss by the year 2010. The scientific community now faces the challenge of assessing the progress made towards this target and beyond. Here, we review current monitoring efforts and propose a global biodiversity monitoring network to complement and enhance these efforts. The network would develop a global sampling programme for indicator taxa (we suggest birds and vascular plants) and would integrate regional sampling programmes for taxa that are locally relevant to the monitoring of biodiversity change. The network would also promote the development of comparable maps of global land cover at regular time intervals. The extent and condition of specific habitat types, such as wetlands and coral reefs, would be monitored based on regional programmes. The data would then be integrated with other environmental and socioeconomic indicators to design responses to reduce biodiversity loss.     

A simple system for monitoring biodiversity in protected areas of a developing country

The achievements of initiatives to strengthen biodiversity conservation in developing countries may be difficult to assess, since most countries have no system for monitoring biodiversity. This paper describes a simple and cost-effective, field-based biodiversity monitoring system developed specifically for areas where specialist staff is lacking. We discuss the preliminary lessons learned from protected areas in the Philippines. Whilst the monitoring system aims to identify trends in biodiversity and its uses so as to guide management action, it also promotes the participation of local people in the management, stimulates discussions about conservation amongst stakeholders and builds the capacity of park staff and communities in management skills. In addition, it seeks to provide people with direction regarding the aims of protected areas, and reinforces the consolidation of existing livelihoods through strengthening community-based resource management systems. The field methods are: (1) standardised recording of routine observations, (2) fixed point photographing, (3) line transect survey, and (4) focus group discussion. Both bio-physical and socio-economic data are used and given equal importance. The system can be sustained using locally available resources. The approach is useful in countries embarking on shared management of park resources with local communities, where rural people depend on use of natural ecosystems, and where the economic resources for park management are limited. We hope this paper will encourage other countries to develop their own biodiversity monitoring system, letting its development become a means for capacity building whilst at the same time supporting the creation of ownership.     

A comparison of the strength of biodiversity effects across multiple functions

In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.     

Mapping from heterogeneous biodiversity monitoring data sources

Field monitoring can vary from simple volunteer opportunistic observations to professional standardised monitoring surveys, leading to a trade-off between data quality and data collection costs. Such variability in data quality may result in biased predictions obtained from species distribution models (SDMs). We aimed to identify the limitations of different monitoring data sources for developing species distribution maps and to evaluate their potential for spatial data integration in a conservation context. Using Maxent, SDMs were generated from three different bird data sources in Catalonia, which differ in the degree of standardisation and available sample size. In addition, an alternative approach for modelling species distributions was applied, which combined the three data sources at a large spatial scale, but then downscaling to the required resolution. Finally, SDM predictions were used to identify species richness and high quality areas (hotspots) from different treatments. Models were evaluated by using high quality Atlas information. We show that both sample size and survey methodology used to collect the data are important in delivering robust information on species distributions. Models based on standardized monitoring provided higher accuracy with a lower sample size, especially when modelling common species. Accuracy of models from opportunistic observations substantially increased when modelling uncommon species, giving similar accuracy to a more standardized survey. Although downscaling data through a SDM approach appears to be a useful tool in cases of data shortage or low data quality and heterogeneity, it will tend to overestimate species distributions. In order to identify distributions of species, data with different quality may be appropriate. However, to identify biodiversity hotspots high quality information is needed.     

A standard unit for monitoring recruitment of fishes to coral reef rubble

We developed a benthic standard monitoring unit for recruitment of fishes (SMURF) to sample fishes that settle in coral rubble and tested it on three fringing reefs on the west coast of Barbados, West Indies. These rubble SMURFs are inexpensive to construct and permit newly settled fishes, including cryptic, secretive and small species, to be quickly and fairly completely (> 83%) removed by divers without returning the unit to the surface. Over a 3-month period involving 9 collections, 32 units on 3 reefs yielded 948 newly settled fishes belonging to 28 taxa (3.3 ± 0.2 S.E. recruits per sample, n = 287) in addition to numerous crustaceans. Most specimens were Sparisoma spp. (Scaridae) (41.8%) and Stegastes partitus (Pomacentridae) (13.6%), with moderate numbers of Scarus spp. (Scaridae) (8.6%), Lythrypnus spp. (Gobiidae) (7.4%), and Pseudogramma gregoryi (Serranidae) (7.2%). Sampling SMURFs at 1-day rather than 11-day intervals yielded approximately twice as many fish, although some taxa were not affected by sampling frequency, indicating taxon-specific differences in post-settlement loss rates. Netting, intended to reduce predation on settlers, did not affect settlement estimates unless algae grew on it, suggesting that the SMURF design minimizes fish predation even in the absence of the netting. Over time, however, the netting resulted in substantial algal growth that was associated with an increase in abundance of Sparisoma spp. and a decrease in the abundance of S. partitus. This suggests that settler estimates are more affected by microhabitat changes from algal growth than by predation. During low settlement periods, SMURFs performed better than light-traps in assessing the daily input of new settlers of two abundant taxa. Eight SMURFs per reef were sufficient to demonstrate differences in settlement rates and temporal correlations in settlement within and among reefs. This study underscores the potential of benthic SMURFs to measure settlement of coral reef fishes at a range of spatio-temporal scales with moderate research cost and effort, and to facilitate the study of the settlement stage of several taxa.     

监测是评估生物多样性保护进展的有效途径

生物多样性保护受到国际社会的广泛关注,继2010年国际生物多样性年之后,联合国又于2010年12月21日宣布2011-2020年为国际生物多样性十年,并号召各国政府和社会各界积极行动起来,为实施<生物多样性公约>第十次缔约方大会通过的2011-2020年生物多样性保护战略规划作出贡献.该战略规划提出了未来十年的全球生物多样性保护目标,包括5个战略目标和20个具体目标(http://www.cbd.int/deci-sion/cop/).     

Optimized monitoring sites for detection of biodiversity trends in China

Properly designed monitoring networks can generate data to understand status and trends of biodiversity, and to assess progress towards conservation targets. However, biodiversity monitoring is often affected by poor sampling design. We proposed an approach to choosing optimized monitoring sites among large areas. Based on comprehensive distribution data of 34,284 vertebrates and vascular plants from 2376 counties in China, we selected 564 optimized monitoring sites (counties) through complementarity analysis and pre-existing knowledge of nature reserves. The optimized monitoring sites are complementary to each other and reasonably distributed, to ensure that maximum species are covered while the total number of sites and monitoring costs are minimized. Incongruence of optimized monitoring sites among different taxa indicates that taxa with different ecological features should be selected for large-scale monitoring programmes. The results of this study have been applied in the design and operation of China Biodiversity Observation Network.     

Photographic assessment of coral chlorophyll contents: Implications for ecophysiological studies and coral monitoring

Assessing environmental impacts on coral reef communities has become a growing discipline. As most corals grow relatively slowly, the common method of monitoring changes in coral communities may limit our ability to identify stressors and stress responses. Since chlorophyll density (amount of chlorophyll a + c₂ per unit of coral surface area) in corals may correlate with coral color, the latter has been suggested as an indicator of the natural seasonal changes in undisturbed (“healthy”) corals, as well as an indicator of environmentally-induced stresses in corals, including those related to bleaching. However, the color of underwater objects as perceived through the naked eye or a camera is affected by attenuation of irradiance with depth, changes in spectral properties of underwater light, turbidity and dissolved materials in the water, among other factors. Thus, methodological issues have so far held back the use of color as a quantitative indicator for chlorophyll content. Presented here are two accurate and easy to use methods for quantitative measurements of chlorophyll density from digital photographs of corals. In these methods, the intensities of the red, green and blue channels in digital photographs were compared to measured chlorophyll densities in Stylophora pistillata. Variations in external light, known to bias the true color in underwater images, were eliminated either by photographing corals through a specially built funnel with an internal light source or by mathematically normalizing color channels to a gray reference scale. In both methods, chlorophyll density was highly correlated with the intensity of the red channel, despite large variations in lighting conditions during the photography.These photographic methods enabled the estimation of natural spatial and temporal changes of the chlorophyll density of corals. By predicting chlorophyll density in corals at very low costs, both methods presented here could facilitate the study of large-scale physiological changes in corals.     

A comparison between coral colonies of the genus Madracis and simulated forms

In addition to experimental studies, computational models provide valuable information about colony development in scleractinian corals. Using our simulation model, we show how environmental factors such as nutrient distribution and light availability affect growth patterns of coral colonies. To compare the simulated coral growth forms with those of real coral colonies, we quantitatively compared our modelling results with coral colonies of the morphologically variable Caribbean coral genus Madracis. Madracis species encompass a relatively large morphological variation in colony morphology and hence represent a suitable genus to compare, for the first time, simulated and real coral growth forms in three dimensions using a quantitative approach. This quantitative analysis of three-dimensional growth forms is based on a number of morphometric parameters (such as branch thickness, branch spacing, etc.). Our results show that simulated coral morphologies share several morphological features with real coral colonies (M. mirabilis, M. decactis, M. formosa and M. carmabi). A significant correlation was found between branch thickness and branch spacing for both real and simulated growth forms. Our present model is able to partly capture the morphological variation in closely related and morphologically variable coral species of the genus Madracis.     

Recent changes in coral assemblages of a South African coral reef, with recommendations for long-term monitoring

Two-mile reef, Sodwana, South Africa is an unusual coral reef, being situated on a submerged fossilized sand dune and being very southerly (27°54). It is a popular Scuba diving venue receiving about 100000 dives year^–1. The line-intercept transect method, as recommended by the global coral reef monitoring network (GCRMN), was used to determine soft coral, hard coral and other benthos percentage cover. Physical coral damage, disease and bleaching were also recorded. Results were compared with those of B. Riegl (1993 – unpublished PhD thesis) 5 to 7 years earlier. The reef appears to be ecologically and highly dynamic. In the interim, there has been an increase in living benthos cover of 22.3% but also an increase in coral bleaching from 0% in 1993 to 1% in 1998. Physical damage, despite the large number of dives on the reef was minimal (1.52%), although it appears as if coral diseases may be increasing. The 20-m transects recommended by GCRMN are too long for this highly rugose reef with its distinct ridges and gullies. It is recommended that benthos cover, coral damage, bleaching and disease should be monitored annually using 40 5-m transects on the reef ridges and 40 5-m transects on the reef slopes.     

Bayesian occupancy monitoring for Annamite endemic biodiversity in central Vietnam

Given the crisis facing South-east Asian biodiversity evidence led conservation, including assessing the impact of innovative protected area management models, is urgently needed. Bayesian statistics provide an intuitive way to interpret biodiversity monitoring data but are largely unused, or poorly understood, by field biologists and protected area managers. We built Bayesian occupancy models for two threatened endemics of the Annamite mountains: northern yellow-cheeked gibbon Nomascus (gabriellae) annamensis and crested argus Rheinardia ocellata ocellata based on auditory surveys in three protected areas in central Vietnam. Occupancy of 2 × 2-km grid cells across the landscape was 0.76 ± SE 0.03 for northern yellow-cheeked gibbon and 0.68 ± SE 0.05 for crested argus. Models predicted higher probability of gibbon occurrence at lower elevations and higher probability of crested argus presence with increasing dense forest cover. Bayesian modeling is a useful tool for assessing the effectiveness of conservation interventions and for measuring progress against conservation goals. The wider application of Bayesian statistics in conservation monitoring should allow more intuitive and user-friendly representation of sampling uncertainty, including visual representation of probability distributions and more rigorous testing for changes in the status of conservation targets.