Sediment suppresses herbivory across a coral reef depth gradient

Sediments are a ubiquitous feature of all coral reefs, yet our understanding of how they affect complex ecological processes on coral reefs is limited. Sediment in algal turfs has been shown to suppress herbivory by coral reef fishes on high-sediment, low-herbivory reef flats. Here, we investigate the role of sediment in suppressing herbivory across a depth gradient (reef base, crest and flat) by observing fish feeding following benthic sediment reductions. We found that sediment suppresses herbivory across all reef zones. Even slight reductions on the reef crest, which has 35 times less sediment than the reef flat, resulted in over 1800 more herbivore bites (h⁻¹ m⁻²). The Acanthuridae (surgeonfishes) were responsible for over 80 per cent of all bites observed, and on the reef crest and flat took over 1500 more bites (h⁻¹ m⁻²) when sediment load was reduced. These findings highlight the role of natural sediment loads in shaping coral reef herbivory and suggest that changes in benthic sediment loads could directly impair reef resilience.     

Spatial variation in the effects of grazing on epilithic algal turfs on the Great Barrier Reef, Australia

Of all benthic components on tropical reefs, algal turfs are the most widespread and the main source of primary productivity. We compared the importance of grazing by herbivores on algal turfs on two zones with marked differences in terms of benthic composition, herbivore biomass and grazing pressure, the inner flat and crest, of an inshore reef on the Great Barrier Reef, Australia. A combination of herbivore exclusion cages and transplants of coral rubble covered by algal turfs between reef zones was used to examine changes in algal turfs over a 4-day experimental period. In situ crest turfs had lower algal height, sediment loads and particulate content than reef flat turfs. Caged samples on the crest exhibited an increase in all three variables. In contrast, in situ and caged treatments on the flat presented algal turfs with similar values for the three analysed variables, with high algal height and heavy particulate and sediment loads. In the absence of cages, reef flat turfs transplanted to the crest had decreased algal height, total particulate material and particulate inorganic content, while the opposite was found in crest turf samples transplanted to the flat. Our results highlight the dynamic nature of algal turfs and the clear differences in the relative importance of herbivory in shaping turf length and sediment load between the reef crest and inner flat.     

Reef demise and back-stepping during the last interglacial, northeast Yucatan

The elevation of reefs and coastal deposits during the last Interglaciation (MIS-5e) indicates that sea level reached a highstand of as much as 6 m above the present, but it is uncertain how rapidly this level was attained and how it impacted reef development. To investigate this problem, I made a detailed sedimentological analysis of a well-dated reef from the northeast coast of the stable Yucatan Peninsula. Two linear reef tracts were delineated which are offset and at different elevations. The lower reef tract crops out along northern shore for 575 m and extends from below present mean sea level to +3 m. The reef crest facies consists of large Acropora palmata colonies dispersed within a coral boulder-gravel and is flanked by an A. cervicornis-dominated reef-front and a large area of lagoonal framework formed by coalesced patches of A. cervicornis and Montastraea spp. Constituents in the upper centimetre of the lower tract are heavily encrusted by a cap of crustose corallines and, in places, are levelled by a discontinuous marine-erosion surface. The upper reef tract crops out ~150 m inland up to an elevation of +5.8 m and parallels the southern section of shore for ~400 m. It also consist of an A. palmata-dominated crest facies flanked by reef-front, back-reef and lagoonal frameworks. In this case, however, lagoonal frameworks are dominated by a sediment-tolerant assemblage of branching coralline algae. Also different is the lack of encrustation by corallines, and the infiltration of upper tract facies by beach-derived shell-gravels from regressive shoreface deposits above. These results indicate that the lower reef tract and lagoonal patch-reefs formed at a sea level of +3 m. Final capping by crustose corallines and discontinuous marine erosion indicates that the lower tract was terminated by the complete demise of corals on the crest but only patchy demise in the lagoon. Areas of continuous framework accretion between the lagoonal patch reefs and the upper reef-tract, however, require that the demise of this reef was ecologically synchronous with initiation of the upper reef-tract, which had back-stepped 100 m into the lagoon. In this new position, the upper tract developed a reef crest that corresponded to a final sea-level position of +6 m. Reef flat development at +5 m and large in-place colonies of A. palmata at the base of the crest unit indicate, however, that sea level must have risen rapidly from +3 to more than +5 m to accommodate back-stepping. This sea-level jump created a higher energy wave field that mobilized back-reef and lagoonal sediments, and the resulting high sediment flux eroded lagoonal framework and prevented the recovery of the submerged lower reef crest. So this single jump in sea level was responsible not only for reef demise and back-stepping but also for marine erosion and suppression of subsequent reef development—features that elsewhere have been used to support multiple sea-level excursions during the last interglacial.     

40 Years of benthic community change on the Caribbean reefs of Curaçao and Bonaire: the rise of slimy cyanobacterial mats

Over the past decades numerous studies have reported declines in stony corals and, in many cases, phase shifts to fleshy macroalgae. However, long-term studies documenting changes in other benthic reef organisms are scarce. Here, we studied changes in cover of corals, algal turfs, benthic cyanobacterial mats, macroalgae, sponges and crustose coralline algae at four reef sites of the Caribbean islands of Curaçao and Bonaire over a time span of 40 yr. Permanent 9 m² quadrats at 10, 20, 30 and 40 m depth were photographed at 3- to 6-yr intervals from 1973 to 2013. The temporal and spatial dynamics in the six dominant benthic groups were assessed based on image point-analysis. Our results show consistent patterns of benthic community change with a decrease in the cover of calcifying organisms across all sites and depths from 32.6 (1973) to 9.2% (2013) for corals and from 6.4 to 1% for crustose coralline algae. Initially, coral cover was replaced by algal turfs increasing from 24.5 (1973) to 38% around the early 1990s. Fleshy macroalgae, still absent in 1973, also proliferated covering 12% of the substratum approximately 20 yr later. However, these new dominants largely declined in abundance from 2002 to 2013 (11 and 2%, respectively), marking the rise of benthic cyanobacterial mats. Cyanobacterial mats became the most dominant benthic component increasing from a mere 7.1 (2002) to 22.2% (2013). The observed increase was paralleled by a small but significant increase in sponge cover (0.5 to 2.3%). Strikingly, this pattern of degradation and phase change occurred over the reef slope down to mesophotic depths of 40 m. These findings suggest that reefs dominated by algae may be less stable than previously thought and that the next phase may be the dominance of slimy cyanobacterial mats with some sponges.     

Influence of Diadema antillarum populations (Echinodermata: Diadematidae) on algal community structure in Jardines de la Reina, Cuba

The 1983-1984 mass mortality of Diadema antillarum produced severe damages on Caribbean reefs contributing to substantial changes in community structure that still persist. Despite the importance of Diadema grazing in structuring coral reefs, available information on current abundances and algal-urchin interactions in Cuba is scarce. We analyzed spatial variations in Diadema abundance and its influence on algal community structure in 22 reef sites in Jardines de la Reina, in June/2004 and April/2005. Urchins were counted in five 30 x 2m transects per site, and algal coverage was estimated in randomly located 0.25m side quadrats (15 per site). Abundances of Diadema were higher at reef crests (0.013-1.553 ind/m2), while reef slope populations showed values up to three orders of magnitude lower and were overgrown by macroalgae (up to 87%, local values). Algal community structure at reef slopes were dominated by macroalgae, especially Dictyota, Lobophora and Halimeda while the most abundant macroalgae at reef crests were Halimeda and Amphiroa. Urchin densities were negatively and positively correlated with mean coverage of macroalgae and crustose coralline algae, respectively, when analyzing data pooled across all sites, but not with data from separate habitats (specially reef crest), suggesting, along with historical fish biomass, that shallow reef community structure is being shaped by the synergistic action of other factors (e.g. fish grazing) rather than the influence of Diadema alone. However, we observed clear signs of Diadema grazing at reef crests and decreased macroalgal cover according to 2001 data, what suggest that grazing intensity at this habitat increased at the same time that Diadema recruitment began to be noticeable. Furthermore, the excessive abundance of macroalgae at reef slopes and the scarcity of crustose coralline algae seems to be due by the almost complete absence of D. antillarum at mid depth reefs, where local densities of this urchin were predominantly low.     

Effects of extreme seasonality on community structure and functional group dynamics of coral reef algae in the southern Red Sea (Eritrea)

Spatial and temporal variation in the biomass of four functional groups of coral reef algae (canopy algae, foliose algae, turf algae and crustose corallines) was investigated in the southern Red Sea. This region is characterised by extremely high summer temperatures (ca. 35°C). Strong seasonal shifts in the relative contribution of each group to the total macroalgal biomass were observed. On the reef flat, canopy and foliose algae dominated in winter, retaining low biomass in summer. On the fore reef, crustose corallines accounted for most of the macroalgal biomass throughout the year. Turf algae contributed least to the total biomass in all reef zones; biomass peaks shifted from midsummer on the inner reef flat to winter in the deeper zones. Biomass correlated negatively with seawater temperature in most groups, but the correlation was positive for turf algae on the shallow reef flat. We hypothesise both direct and indirect effects of the strong seasonality.

Comparing early embryo mortality in dairy cows during hot and cool seasons of the year

The objectives of this study were to identify the level and stage of embryonic mortality that occur in dairy cows during hot and cool seasons of the year. Experimental dairy cows, of varying ages, were artificially inseminated with frozen-thawed semen from proven Holstein sires. Females on each dairy unit were then randomly allocated to one of three experimental groups after partitioning by day of artificial insemination, days post partum, parity, and current milk production level. In Group I and Group II, nonsurgical embryo collection was performed on each cow using Dulbecco's phosphate-buffered saline as the flushing medium. Embryos from cows in Group I were collected on Days 6 or 7 post insemination during the hot (n=93) and cool (n=64) seasons. Embryos from cows in Group II were collected on Days 13 or 14 post insemination during the hot (n=97) and cool (n=63) seasons. In Group III, contemporary control cows were also inseminated during the hot (n=106) and cool (n=106) seasons, and fetal heart beat was evaluated via ultrasound between Days 25 and 35 following insemination. Embryo viability decreased (P<0.05) from 59% at Day 7 to 27% at Day 14 in the hot season, but was not decreased during the cool season (52 vs. 60%). Pregnancy rate at Days 25 to 35 was 21% in the hot season, which was less (P<0.05) than the 36% in the cool season. The percentage of unfertilized ova collected in both the hot and cool seasons suggests that fertilization failure was not affected by season of breeding. In summary, embryonic loss after Day 7 of pregnancy appears to be a problem in this hot, dry climate.     

Application of diet theory reveals context-dependent foraging preferences in an herbivorous coral reef fish

Dietary preferences of grazers can drive spatial variability in top-down control of autotroph communities, because diet composition may depend on the relative availability of autotroph species. On Caribbean coral reefs, parrotfish grazing is important in limiting macroalgae, but parrotfish dietary preferences are poorly understood. We applied diet-switching analysis to quantify the foraging preferences of the redband parrotfish (Sparisoma aurofrenatum). At 12 Caribbean reefs, we observed 293 redband parrotfish in 5-min feeding bouts and quantified relative benthic algal cover using quadrats. The primary diet items were macroalgal turfs, Halimeda spp., and foliose macroalgae (primarily Dictyota spp. and Lobophora spp.). When each resource was evaluated independently, there were only weak relationships between resource cover and foraging effort (number of bites taken). Electivity for each resource also showed no pattern, varying from positive (preference for the resource) to negative (avoidance) across sites. However, a diet-switching analysis consisting of pairwise comparisons of relative cover and relative foraging effort revealed clearer patterns: parrotfish (a) preferred Halimeda and macroalgal turfs equally, and those two resources were highly substitutable; (b) preferred Halimeda to foliose macroalgae, but those two resources were complementary; and (c) also preferred turf to foliose macroalgae, and those resources were also complementary. Thus parrotfish grazing rates depend on relative, not absolute, abundance of macroalgal types, due to differences in substitutability among resources. Application of similar analyses may help predict potential changes in foraging effort of benthic grazers over spatial gradients that could inform expectations for reef recovery following the protection of herbivore populations.     

3-D distribution of nongeniculate corallinales: a case study from a reef crest of South Sinai (Red Sea,Egypt)

An innovative technique for the estimation of species and growth-form abundance of coralline algae, including information on their vitality, was adopted on the reef crest of Ras Nosrani and Coral Bay, South Sinai. Data of coralline abundance from visual census and collection of voucher specimens were plotted on a 3-D sketched representation of the horizontal and vertical planes of the reef crest and of its crannies. Coralline dominance at the two investigated sites was not significantly different, with values ranging from 8.55 and 10.06% on the vertical plane and from 5.3 to 7.17% on the horizontal plane. About one-third of total corallines of the South Sinai reef crest was located in crannies, where the algae are completely overlooked by routine field surveys. Pink to violet, healthy corallines with encrusting growth-form, mainly belonging to Hydrolithon onkodes and Neogoniolithon, with subordinate fruticose Lithophyllum kotschyanum dominated the reef crest at both sites. The fruticose growth form, usually associated with L. kotschyanum, was more common in the horizontal than in the vertical plane. Purple, healthy, encrusting Sporolithon uncommonly occurred. Whitish, gray or green unhealthy or dead corallines were more common on the horizontal plane at both sites, possibly resulting from excessive solar radiation.     

Rapid fluctuations in flow and water-column properties in Asan Bay, Guam: implications for selective resilience of coral reefs in warming seas

Hydrodynamics and water-column properties were investigated off west-central Guam from July 2007 through January 2008. Rapid fluctuations, on time scales of 10s of min, in currents, temperature, salinity, and acoustic backscatter were observed to occur on sub-diurnal frequencies along more than 2 km of the fore reef but not at the reef crest. During periods characterized by higher sea-surface temperatures (SSTs), weaker wind forcing, smaller ocean surface waves, and greater thermal stratification, rapid decreases in temperature and concurrent rapid increases in salinity and acoustic backscatter coincided with onshore-directed near-bed currents and offshore-directed near-surface currents. During the study, these cool-water events, on average, lasted 2.3 h and decreased the water temperature 0.57 °C, increased the salinity 0.25 PSU, and were two orders of magnitude more prevalent during the summer season than the winter. During the summer season when the average satellite-derived SST anomaly was +0.63 °C, these cooling events, on average, lowered the temperature 1.14 °C along the fore reef but only 0.11 °C along the reef crest. The rapid shifts appear to be the result of internal tidal bores pumping cooler, more saline, higher-backscatter oceanic water from depths >50 m over cross-shore distances of 100 s of m into the warmer, less saline waters at depths of 20 m and shallower. Such internal bores appear to have the potential to buffer shallow coral reefs from predicted increases in SSTs by bringing cool, offshore water to shallow coral environments. These cooling internal bores may also provide additional benefits to offset stress such as supplying food to thermally stressed corals, reducing stress due to ultraviolet radiation and/or low salinity, and delivering coral larvae from deeper reefs not impacted by surface thermal stress. Thus, the presence of internal bores might be an important factor locally in the resilience of select coral reefs facing increased thermal stress.     

FIELD MEASUREMENTS OF INORGANIC NITROGEN UPTAKE BY EPIFLORA COMPONENTS OF THE SEAGRASS POSIDONIA OCEANICA (MONOCOTYLEDONS,POSIDONIACEAE)1

Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass, and specific composition of this epiphyte–seagrass association are impacted by anthropogenic increase of nutrient load in this oligotrophic area. In this context, nitrogen uptake by P. oceanica and its epiflora was measured using the isotope ¹⁵N at a 10 m depth in the Revellata Bay (Corsica, Mediterranean Sea). Epiflora components showed various seasonal patterns of biomass and abundance. The epiphytic brown algae appeared at the end of spring, later than the crustose corallines, and after the nitrate peak in the bay. Because of their later development in the season, epiphytic brown algae mostly rely on ammonium for their N needs. We hypothesize that the temporal succession of epiphytic organisms plays a crucial role in the N dynamics of this community under natural conditions. The epiphytic brown algae, which have a growth rate one order of magnitude greater than that of crustose corallines, showed lower N‐uptake rates. The greater N‐uptake rates of crustose corallines probably reflect the greater N requirements (i.e., lower C/N ratios) of red algae. We determined that the epiflora incorporated ammonium and nitrate more rapidly than their host. Nevertheless, when biomass was taken into account, P. oceanica was the most important contributor to N uptake from the water column by benthic macrophytes in this seagrass bed.     

The population and community structure of Hawaiian fringing-reef crustose Corallinaceae (Rhodophyta,Cryptonemiales)

Measurements of cover, relative density, and frequency are given for the major reefbuilders on the Waikiki fringing reef. Crustose coralline algae cover 39% of the reef surface and exceed all other organisms as the major builders and consolidators of reef materials. An unidentified coralline (melobesioid C) covers the greatest area (17 %), but Hydrollthon reinboldii (Weber-van Bosse & Foslie) Foslie (11 % cover) because of its thicker thalli and higher relative density (45 %) and frequency (68 %) values is the primary limestone former. Melobesioid C ranks second and Sporolithon erythraeum (Rothpletz) Kylin (6 % cover) third in relative importance. Porolithon onkodes (Heydrich) Foslie (3 % cover), although shown by its low density (4 %) and frequency (6 %) to have a comparatively restricted distribution, is more important than P. gardineri (Foslie) Foslie (2 % cover). P. onkodes maintains and provides the surf-resistant reef edge and is, therefore, of great ecological importance. Coelenterate corals cover less than 1 % of the total area and are relatively unimportant on the fringing reef. The hypothesis is developed that the high ratio (200 : 1) of crustose corallines to corals at Waikiki may be partly due to increases in eutrophication.Experimental evidence shows that P. onkodes can withstand intense illumination and is thereby unique among Hawaiian crustose Corallinaceae. Sporolithon erythraeum is more typical of other crustose corallines since it is physiologically adapted to low-light habitats.     

Grazer biomass correlates more strongly with production than with biomass of algal turfs on a coral reef

The biomass of large herbivorous grazing fish on the shallow reef crest of Myrmidon Reef, Great Barrier Reef, is 7.0 times that on the reef slope (15 m depth), and 2.3 times that on the reef flat. Biomass of algal turfs on the crest was only 1.4 and 1.0 times that on the slope and flat, respectively. In contrast, rate of production of algal turfs on the crest was 5.3 and 2.8 times that on the slope and flat, respectively. A multiple correlation between large grazer biomass, algal turf biomass, and algal turf production across the three zones showed that only rate of algal production correlated significantly with large grazer biomass (algal production p=0.007, algal biomass p=0.418). This result suggests that large grazers may aggregate in zones of highest algal turf production. The mechanisms by which fish respond to habitat-specific differences in food production remain unclear.     

Development rates,fecundity and survival of developmental stages of the ticksRhipicephalus appendiculatus,Boophilus decoloratus andB. microplus under field conditions in Zimbabwe

To determine development rates, fecundity and survival ofRhipicephalus appendiculatus, Boophilus decoloratus andB. microplus, a study was carried out in long and short grass in the highveld of Zimbabwe. Engorged adult females of the three species and engorged larvae and nymphs ofR. appendiculatus were buried beneath the soil in small cages in the rainy, cool and hot seasons in 1980 and 1981. Half the number of cages were examined regularly to determine development rates and half were left undisturbed to determine survival rates and the fecundity of engorged females. Development was most rapid during warm conditions and slowest during cool conditions, but high temperatures appeared to prolong the preoviposition periods of all species. The relationship between fluctuating temperatures and rate of development in the field was defined using a least-squares procedure. Survival of engorged females was usually high, but was reduced by predation when they were not protected. Fecundity was reduced in long grass during the cool season and in short grass during the hot season. A higher percentage of eggs hatched in the rainy season than in the cool or dry seasons. The survival of engorged larvae and nymphs was usually high in all seasons. Engorged nymphs were the hardiest stage and eggs the most suceptible stage to adverse microclimatic conditions.     

Seasonal variation in follicular dynamics of superovulated Indian water buffalo

The ovaries of 5 buffalo were examined daily by ultrasound beginning at Day 3 of the estrous cycle, followed by superovulation between Days 11 and 13 of the cycle in both the wet cool and dry hot seasons. Daily ultrasonographic observations of the ovaries were recorded on a videotape and were used to assess the progression of both the large (dominant) and the next to the large (sub-dominant) follicles as well as the numbers of follicles in the small (4 to 6 mm), medium (7 to 10 mm) and large (> 10 mm) size categories in the 2 seasons before and during the superovulation treatment. Greater numbers of small (P < 0.05) and medium size follicles (P < 0.01) were available before the start of the superovulatory treatment in the buffalo during the dry hot season. The turnover of follicles from medium to large size classes also occurred sooner (P < 0.01) and was of higher magnitude (P < 0.05) during the treatment in the dry hot season. However, the number of corpora lutea at palpation per rectum (2.8 +/- 0.7 vs 2.2 +/- 0.6), the serum progesterone concentration (1.6 +/- 0.3 vs 1.4 +/- 0.1 ng/ml), and the yield of embryos on Day 6 (0.2 +/- 0.2 vs 0.6 +/- 0.2) did not differ significantly between the dry hot and the wet cool season. None of the embryos recovered during the dry hot season were transferable, which remains unexplained.     

168 Cell Wall Proteomics of the Green Alga Haematococcus Pluvialis (Chlorophyceae)

Coral reefs of US-held islands in the central Pacific Ocean are among the most pristine in the world and represent over 93% of the reef systems under United States jurisdiction. The remote location of many islands has limited past algal research, resulting in incomplete understanding of species diversity, quantity, and ecology. Starting in 2000, the Coral Reef Ecosystem Investigation (CREI) began rapid ecological assessments on many Pacific island reefs to monitor ecological changes in reef biota over time. During the past year, algal efforts have concentrated on the French Frigate Shoals (Northwestern Hawaiian Islands) where we have increased the number of algal species reported by 1000%. Additionally, species new to science, including Acrosymphyton brainardii and Scinaia huismanii, have been described. Quantitative field sampling using a photoquadrat method is revealing species of the green algae Halimeda and Microdicyton to be ecological dominants in many areas during late summer/early autumn. Preliminary analyses with Primer software show species composition and abundance of all benthic organisms to differ significantly between most field sites sampled. Additional benthic habitat mapping of Pacific island reefs by CREI researchers is breaking the long-held paradigm that macroalgal cover is minimal in healthy tropical reef systems. Videotape analyses of benthic communities often find over 50% algal cover from 1 to 20 meter depths in many locations. Common ratios of macroalgae, turf algae, and crustose coralline algae to corals, other benthic organisms and substrate types on US Pacific reefs are being calculated for the first time.     

Responses of algal communities to gradients in herbivore biomass and water quality in Marovo Lagoon, Solomon Islands

Settlement tiles were used to characterise and quantify coral reef associated algal communities along water quality and herbivory gradients from terrestrial influenced near shore sites to oceanic passage sites in Marovo Lagoon, the Solomon Islands. After 6 months, settlement tile communities from inshore reefs were dominated by high biomass algal turfs (filamentous algae and cyanobacteria) whereas tiles located on offshore reefs were characterised by a mixed low biomass community of calcareous crustose algae, fleshy crustose algae and bare tile. The exclusion of macrograzers, via caging of tiles, on the outer reef sites resulted in the development of an algal turf community similar to that observed on inshore reefs. Caging on the inshore reef tiles had a limited impact on community composition or biomass. Water quality and herbivorous fish biomass were quantified at each site to elucidate factors that might influence algal community structure across the lagoon. Herbivore biomass was the dominant driver of algal community structure. Algal biomass on the other hand was controlled by both herbivory and water quality (particularly dissolved nutrients). This study demonstrates that algal communities on settlement tiles are an indicator capable of integrating the impacts of water quality and herbivory over a small spatial scale (kilometres) and short temporal scale (months), where other environmental drivers (current, light, regional variability) are constant.     

Influence of season and reproductive status on peripheral plasma progesterone levels in the lactating bovine

Data collected monthly for one calendar year from Holstein cows lactating under Louisiana ambient climatic conditions comprised a total of 264 cowmonths. The year was divided into seasons of cool, intermediate, and hot temperatures. A highly significant (P<0.01) relationship between plasma progesterone and animal age (r=–0.57) was observed. Plasma progesterone concentrations in the hot season (4.6 ng/ ml) were significantly (P<0.01) higher than concentrations in the cool and intermediate seasons (3.4 and 3.8 ng/ ml, respectively). Plasma cortisol concentrations were lower (P<0.01) in the hot season than in the cool and intermediate seasons and suggested the adrenal cortex did not contribute to the increase in progesterone concentrations which occured in the hot season. A significant (P<0.01) positive correlation (r=0.45) between cortisol and progesterone was observed. Reproductive status did not have a statistically significant effect on progesterone levels and the affect of season on progesterone concentrations was consistant across all reproductive status. Plasma progesterone levels in the anestrus animals (3.9 ng/ ml) suggested progesterone secretion was responsible for their failure to cycle. Similar progesterone levels were observed in normal (3.5 ng/ ml) and repeat breeders (3.6 ng/ ml).Presented at the Seventh International Biometeorological Congress, 17–23 August 1976, College Park, Maryland, USA.     

Daily and hourly movement of male desert-dwelling elephants

The daily and hourly movements of eight male desert-dwelling elephants of various ages (12–45 years old) were determined hourly by global positioning system (GPS)/telemetry collars during the wet, cold dry and hot dry seasons of 2006 in northwest Namibia. The average daily movement in the wet season was greater than that observed during either the cold dry or the hot dry seasons. A similar difference was also observed for the movement rates, with the highest average rate of hourly movement recorded during the wet season. The diurnal movements (both distance and rate) were greater than those in the nocturnal hours during the wet season, whilst during the cold dry and hot dry season the reverse was true. The daily cycle of movement also changed seasonally, with greatest movement rates observed during the wet season between 11.00–20.00 hours, during the cold dry season between 14.00–21.00 hours; and between 04.00–11.00 hours during the hot dry season. Periods of decreased movement rates were observed between 09.00–10.00 and 02.00–03.00 hours in the wet season; 03.00–06.00 and 11.00–13.00 hours in the cold dry season; and 01.00–03.00 and 12.00–14.00 hours during the hot dry season.     

167 Algal Monitoring Studies on Remote Tropical Pacific Reefs

Coral reefs of US‐held islands in the central Pacific Ocean are among the most pristine in the world and represent over 93% of the reef systems under United States jurisdiction. The remote location of many islands has limited past algal research, resulting in incomplete understanding of species diversity, quantity, and ecology. Starting in 2000, the Coral Reef Ecosystem Investigation (CREI) began rapid ecological assessments on many Pacific island reefs to monitor ecological changes in reef biota over time. During the past year, algal efforts have concentrated on the French Frigate Shoals (Northwestern Hawaiian Islands) where we have increased the number of algal species reported by 1000%. Additionally, species new to science, including Acrosymphyton brainardii and Scinaia huismanii, have been described. Quantitative field sampling using a photoquadrat method is revealing species of the green algae Halimeda and Microdicyton to be ecological dominants in many areas during late summer/early autumn. Preliminary analyses with Primer software show species composition and abundance of all benthic organisms to differ significantly between most field sites sampled. Additional benthic habitat mapping of Pacific island reefs by CREI researchers is breaking the long‐held paradigm that macroalgal cover is minimal in healthy tropical reef systems. Videotape analyses of benthic communities often find over 50% algal cover from 1 to 20 meter depths in many locations. Common ratios of macroalgae, turf algae, and crustose coralline algae to corals, other benthic organisms and substrate types on US Pacific reefs are being calculated for the first time.