Biofluorescence as a survey tool for cryptic marine species

As ecosystems come under increasing anthropogenic pressure, rare species face the highest risk of extinction. Paradoxically, data necessary to evaluate the conservation status of rare species are often lacking because of the challenges of detecting species with low abundance. One group of fishes subject to this undersampling bias are those with cryptic body patterns. Twenty‐one percent of cryptic fish species assessed for their extinction risk (International Union for Conservation of Nature [IUCN]) are data deficient. We developed a nondestructive method for surveying cryptically patterned marine fishes based on the presence of biofluorescence (underwater biofluorescence census, UBC). Blue LED torches were used to investigate how widespread biofluorescence was in cryptic reef fishes in the Coral Triangle region. The effectiveness of UBC to generate abundance data was tested on a data‐deficient pygmy seahorse species (Hippocampus bargibanti) and compared with data obtained from standard underwater visual census (UVC) surveys. We recorded 95 reef fish species displaying biofluorescence, 73 of which had not been previously described as biofluorescent. Of those fish with cryptic patterns, 87% were biofluorescent compared with 9% for noncryptic fishes. The probability of species displaying biofluorescence was 70.9 times greater for cryptic species than for noncryptic species. Almost twice the number of H. bargibanti was counted using the UBC compared with UVC. For 2 triplefin species (Ucla xenogrammus, Enneapterygius tutuilae), the abundance detected with UBC was triple that detected with UVC. The UBC method was effective at finding cryptic species that would otherwise be difficult to detect and thus will reduce interobserver variability inherent to UVC surveys. Biofluorescence is ubiquitous in cryptic fishes, making this method applicable across a wide range of species. Data collected using UBC could be used with multiple IUCN criteria to assess the extinction risk of cryptic species. Adopting this technique will enhance researchers’ ability to survey cryptic species and facilitate management and conservation of cryptic marine species.     

Population structure of four species of porcellanid crabs (Decapoda: Anomura) occurring on the coast of Karachi

The population structure of 4 species of porcellanid crabs, including 2 species of Petrolisthes (P. boscii and P. rufescens) and 2 of Pachycheles (P. tomentosus and P. natalensis) was investigated. Sex ratios deviated from the expected 1:1 distribution in some size classes of the 4 species, but conformed in general to this pattern on the entire population basis. Probability curves developed from sex ratios differ markedly in shape and slope and resemble Wenner's (1972) anomalous and intermediate types. Ovigerous females of Petrolisthes boscii occurred for 9 months, of P. rufescens for 11 months; those of Pachycheles tomentosus and P. natalensis occurred throughout the year. In every size class, a considerably higher number of female Pachycheles tomentosus and P. natalensis became ovigerous than in Petrolisthes boscii and P. rufescens. Size-frequency distributions of the 4 species were unimodal, indicating that recruitment to crab populations was gradual. Juveniles of Petrolisthes boscii and P. rufescens were most abundant towards the commencement of the southwest monsoon season, in June–July; juveniles of Pachycheles tomentosus and P. natalensis were most abundant during the premonsoon month of March. Thirteen percent of Pachycheles natalensis were infected by a bopyrid parasite; the bopyrid also infected 5.2% of Petrolisthes rufescens and 0.6% of P. boscii. The latter two species were also infected by a rhizocephalan parasite, the infection rates being inverse to those by the bopyrid, i.e., 0.3 and 6.4%, respectively.     

Reproductive cycles of tropical sea cucumbers (Echinodermata: Holothuroidea) in southern Taiwan

Reproductive cycles of Afrocucumis africana (Dendrochirotida), Actinopyga echinites, Holothuria leucospilota, H. cinerascens, H. difficilis (Aspidochirotida), Synaptamaculata, Opheodesoma grisea, Patinapta taiwaniensis and Polycheira rufescens (Apodida), representing three orders of intertidal holothurians in southern Taiwan, were determined by gonad index and histological examination from March 1990 through September 1991. All nine species of holothurians have annual spawning periods lasting 2 to 4 mo in spring or summer. The early spawning of H. cinerascens and P. rufescens (suspension feeders) suggests that their feeding mode is related to food resources and may influence the reproductive period. In the direct-developing dendrochirotid (suspension feeder), gonad development occurs in cool months, and gametes are released at the beginning of warm months. In indirect-developing aspidochirotid and apodid (deposit feeder), gamete release occurs in late spring or summer and appears to be correlated with summer phytoplankton growth. The holothurians in the present study display spawning periodicity and duration similar to those of temperate species. Four species of holothurians lengthened spawning season with decreased latitude.     

Selective feeding of littoral harpacticoids on diatom algae: hungry gourmands?

We studied benthic harpacticoid grazing on diatom algae from two sites on the White Sea intertidal sandflat. Diatoms from sediments and from harpacticoid gut contents were sampled in situ, identified and counted, and grazing rates were calculated by two ways: (1) using potential daily ration estimations and (2) from the gut content and gut-residence time data. Paraleptastacus kliei did not contain any diatoms in the guts and presumably fed on other objects (bacteria or flagellates). Two other dominating species studied, Heterolaophonte minuta and Huntemannia jadensis, contained an average of 604 and 222 diatom cells per specimen. Diet composition differed significantly from the natural algal community. Two diatoms of intermediate cell size (Nitzschia palea var. debilis and Navicula sp.) contributed 92–97% of gut content for H. minuta and 58–81% for Hn. jadensis, whereas these diatoms amounted to only about 10% of biomass in native community. Mean consumption rates were estimated as 50–200 μg of wet biomass/day/cm², so the harpacticoids grazed only between 3 and 11% of the total microalgae biomass per day. The grazing impact on the two preferred diatom populations, however, was much more intensive, 10–30% per day for Navicula sp. and 55–228% for N. palea. Therefore, native harpacticoid populations demonstrate highly selective feeding and could be strongly limited by their food in spite of seemingly plentiful total abundance of microphytobenthos. This disproportionally high grazing pressure upon some species apparently could affect the structure of microalgae communities resulting in low relative abundance of mid-sized forms. We hypothesize that a very dynamic spatio-temporal distribution of epibenthic harpacticoids (short-living micropatches) may be the possible adaptation to such local food limitation.     

Effects of environmental factors and body size on rates of oxygen consumption in Archaeomysis grebnitzkii and Neomysis awatschensis (Crustacea: Mysidae)

The rates of oxygen consumption in relation to oxygen tension, temperature, salinity and body size were determined for Archaeomysis grebnitzkii Czerniavsky and Neomysis awatschensis (Brandt). Oxygen uptake was regulated by both species down to an oxygen tension of about 50 mm Hg (30% of saturation value); below this level, it was related to the oxygen tension in the medium. Oxygen tension below 20 mm Hg was lethal. A statistically significant interaction was noted for the effects of species, temperature, and salinity. In general, oxygen-uptake rate decreased with decreasing salinity in both species. The effect of size is expressed as a power function of body weight. The regression coefficients of oxygen consumption on body weight, 0.70 for A. grebnitzkii and 0.62 for N. awatschensis, were found to be significantly different from each other.Contribution No. 726 from the Department of Oceanography, University of Washington, Seattle, USA.     

Diel feeding behavior of neritic copepods during spring and fall blooms in Akkeshi Bay,eastern coast of Hokkaido,Japan

In situ diel feeding behavior of neritic copepods was investigated using the gut fluorescence method, during spring and fall bloom periods in Akkeshi Bay, on the eastern coast of Hokkaido, Japan. Acartia omorii and Paracalanus sp. were the dominant species during the fall, and Pseudocalanus spp. and A. longiremis during the spring. During both bloom periods, diel rhythms were always observed for the gut pigment contents of these dominant copepods, although there were interspecific differences in the pattern. The maximum gut pigment content was always observed during the night and the minimum during the day. For all species, except Paracalanus sp., the average gut pigment content during the night was significantly higher (p<0.05) than during daytime by factors of between 1.5 and 2.7. There were no significant differences between the gut evacuation rate constants determined during the day and the night, and initial gut pigment content had no effect on the value of gut evacuation rate constants. The instantaneous ingestion rates of individual copepods calculated from gut pigment and the mean value of gut evacuation rate constants followed the same diel rhythms as gut pigment contents. Copepod daily ingestion rates were higher than the daily requirements for respiration during both bloom periods. Estimated daily ration was 40 to 91% of body carbon during the fall bloom, and 17 to 28% during the spring bloom. The higher daily rations during fall were probably due to the difference in in situ temperature (ca. 14°C).     

Gut length and mass in herbivorous and carnivorous prickleback fishes (Teleostei: Stichaeidae): ontogenetic, dietary, and phylogenetic effects

Relative gut length, Zihler’s index, and relative gut mass were measured in four species of prickleback fishes and the effects of ontogeny, diet, and phylogeny on these gut dimensions were determined. Of the four species, Cebidichthys violaceus and Xiphister mucosus shift to herbivory with growth (>45 mm SL), whereas X. atropurpureus and Anoplarchus purpurescens remain carnivores. A. purpurescens belongs to a carnivorous clade, and the three other species belong to an adjacent, herbivorous clade. Gut dimensions were compared in three feeding categories of the four species: (1) small, wild-caught juveniles representing the carnivorous condition before two species shift to herbivory; (2) larger, wild-caught juveniles representing the natural diet condition of the two carnivores and the two species that have shifted to herbivory; and (3) larger, laboratory-raised juveniles produced by feeding a high-protein artificial diet to small juveniles until they have reached the size of the larger, wild-caught juveniles. Comparisons of gut dimensions in categories (1) versus (2) tested for an ontogenetic effect, in (2) versus (3) for a dietary effect, and within each category for a phylogenetic effect. C. violaceus and X. mucosus increased gut dimensions with increase in body size and did not change ontogenetic trajectory in gut dimensions on the high-protein artificial diet, suggesting that they are genetically programmed to develop relatively large guts associated with herbivory. X. atropurpureus increased its gut dimensions with increase in size similar to its sister taxon, X. mucosus, suggesting a phylogenetic influence, but decreased gut dimensions on the high-protein artificial diet, suggesting phenotypic plasticity. Nevertheless, X. atropurpureus displayed a larger gut than A. purpurescens, further evidence that it evolved in an herbivorous clade. A. purpurescens possessed a relatively small gut that was little affected by ontogeny or diet. Ontogeny and phylogeny more than diet appear to influence gut dimensions in the four species, thus favoring genetic adaptation over phenotypic plasticity as the major force acting on digestive system features in the two prickleback clades.     

Motile cryptofauna of Tuléar reef flats

A study of the calcareous tube-building polychaete Hydroides dianthus (Verrill) in a temperate estuary (Delaware Bay, USA) revealed an assemblage that was strongly associated with the serpulid. This polychaete species provided numerous microhabitats by means of its tubes and sediment enriched with tube fragments. Quantitative associations for winter and summer tube heads showed that 17 and 12 species, respectively, were statistically dependent on H. dianthus. There were significant associations between number of species, number of individuals, mean number of animals, standard deviation, the size of the tube clump for both seasons (winter and summer), and for scaled standard deviation (SDN) and species diversity (H) during the winter. Successional development of the serpulid assemblage starts with the settling of H. dianthus, progresses through growth, maturation, mortality, and the interaction of associates and predators, resulting in a highly diverse benthic assemblage in this temperate estuary.     

Feeding,food preference,and the uptake of food energy by the supralittoral isopod Ligia pallasii

Analyses of gut contents of freshly collected Ligia pallasii (Brandt) showed that the principal foods were encrusting diatoms, insect larvae, occasional members of the same species, and a variety of red and green seaweeds growing in the upper interiidal tidepool habitat. L. pallasii prefers to eat the green seaweed Ulva sp., and the brown alga Nereocystis luetkeana, when given a choice between several seaweeds, although neither of these forms is normally accessible to the isopods. The absorption (assimilation) of food-energy was 78% on a diet of Ulva and 55 to 76% on a diet of N. luetkeana—representative values for an algivorous invertebrate. A correlation analysis on the relationship of feeding preference of L. pallasii with calorific value of 7 potential seaweed foods suggested that feeding preference in this species is related to factors other than energy content of the food. Food preferences of invertebrates are discussed in relation to calorific value, accessibility, and to various nutritional factors.     

Associations of Forest Cover,Fragment Area,and Connectivity with Neotropical Understory Bird Species Richness and Abundance

Theoretical and empirical studies demonstrate that the total amount of forest and the size and connectivity of fragments have nonlinear effects on species survival. We tested how habitat amount and configuration affect understory bird species richness and abundance. We used mist nets (almost 34,000 net hours) to sample birds in 53 Atlantic Forest fragments in southeastern Brazil. Fragments were distributed among 3 10,800‐ha landscapes. The remaining forest in these landscapes was below (10% forest cover), similar to (30%), and above (50%) the theoretical fragmentation threshold (approximately 30%) below which the effects of fragmentation should be intensified. Species‐richness estimates were significantly higher (F= 3715, p = 0.00) where 50% of the forest remained, which suggests a species occurrence threshold of 30–50% forest, which is higher than usually occurs (<30%). Relations between forest cover and species richness differed depending on species sensitivity to forest conversion and fragmentation. For less sensitive species, species richness decreased as forest cover increased, whereas for highly sensitive species the opposite occurred. For sensitive species, species richness and the amount of forest cover were positively related, particularly when forest cover was 30–50%. Fragment size and connectivity were related to species richness and abundance in all landscapes, not just below the 30% threshold. Where 10% of the forest remained, fragment size was more related to species richness and abundance than connectivity. However, the relation between connectivity and species richness and abundance was stronger where 30% of the landscape was forested. Where 50% of the landscape was forested, fragment size and connectivity were both related to species richness and abundance. Our results demonstrated a rapid loss of species at relatively high levels of forest cover (30–50%). Highly sensitive species were 3‐4 times more common above the 30–50% threshold than below it; however, our results do not support a unique fragmentation threshold. Asociaciones de la Cobertura Forestal, Superficie del Fragmento y Conectividad con la Riqueza y Abundancia de Aves Neotropicales de Sotobosque     

Comparative study of vanadium biokinetics in three species of echinoderms

Vanadium-48 (as vanadate) was used to study the uptake, tissue distribution, depuration and food-chain transfer of vanadium through 3 species of echinoderms: the seastar Marthasterias glacialis L., the sea urchin Paracentrotus lividus Lmk. and the holothurian Holothuria forskali D.Ch.; all were collected from the littoral zone near Monaco. Uptake by all species was relativelyslow; after 3 wk exposure, isotopic equilibrium had not been reached and whole-body concentration factors ranged from 5 and 7 in the holothurian and sea urchin, respectively, to 18 in the seastar. Sixty-three to 77% of the incorporated radiotracer was associated with the body wall or test, suggesting surface sorption as the principal mechanism governing uptake from water. Stable vanadium measurements confirmed the preponderance of this element in the external hard parts of the echinoderms; however, concentration factors based on stable vanadium levels were significantly higher than those measured experimentally. Subsequent vanadium depuration rates were also species-dependent, with biological half-times for loss ranging from approximately 50 d in the sea urchin and holothurian to 123 d in the seastar. Food-chain transfer experiments indicated that seastars can assimilate and retain a large fraction of the vanadium ingested with food whereas sea urchins appear to lack this capability. The relative importance of the water and food input pathway in achieving vanadium levels in echinoderms is discussed in light of results of ⁴⁸V distribution in experimental individuals and stable vanadium distribution in samples from the natural environment.     

Influence of occupant microhabitat on the composition of encrusting communities on gastropod shells

The exploitation of microhabitats is widely considered to increase biodiversity in marine ecosystems. Although intertidal hermit crabs and gastropods may inhabit the same shell type and shore level, their microhabitat may differ depending on the state of the tide. On the south coast of Wales the hermit crab Pagurus bernhardus mainly inhabits the shells of Nucella lapillus (84%). Hermit crab shells had a significantly different encrusting community compared with live N. lapillus shells. At low tide the live gastropods were found on exposed rock surfaces whereas hermit crabs were restricted to tidal pools. Communities encrusting live gastropod shells were characterised by lower species richness and abundance compared with shells inhabited by hermit crabs (12 species found in total). A greater abundance and richness of epibionts was recorded from both shell types during the summer compared with winter. Differences in community composition between shell occupant types were attributed to microhabitats used by gastropods and hermit crabs and the associated desiccation pressures, rather than competitive interactions or shell characteristics. This contradicts earlier studies of subtidal shells where biological processes were considered more important than physical factors in controlling species abundance and richness patterns. The use of rockpool microhabitats by hermit crabs increases the biodiversity of rocky shores, as some species commonly found on hermit-crab-inhabited shells were rare in other local habitats.Communicated by J.P. Thorpe, Port Erin     

Abalones and sea urchins in an area inhabited by sea otters

Abalones (Haliotis spp.) and sea urchins (Strongylocentrotus spp.) are part of the subtidal fauna in the kelp bed off Hopkins Marine Station, Pacific Grove, California, USA, a protected marine reserve. Although these animals have been preyed upon by sea otters for over 10 years, their densities are gubstantial (Haliotis spp.: 0.21/m²; Strongylocentrotus spp.: 0.22/m²), and two species, H. rufescens (Swainson) and S. purpuratus (Stimpson), have wide size distributions indicating broad age ranges. Most of the adult abalones and sea urchins occur clustered deep in crevices, either as a direct result of sea-otter predation or because ample drift of algal food reduces foraging activities. Abalones tend to occur in larger crevices than sea urchins, and competition for suitable crevice space may exist among these large, invertebrate, algal-drift feeders.     

Physiological responses to fluctuation in temperature of salinity in invertebrates. Adaptations ofAlpheus viridari (Decapoda,Crustacea),Terebellides parva (Polychaeta) andGolfinigia cylindrata (Sipunculida) to the mangrove habitat

The snapping shrimpAlpheus viridari (Armstrong, 1949), the polychaeteTerebellides parva Solis-Weiss, Fauchald and Blankensteyn 1990, and the sipunculanGolfingia cylindrata (Keferstein, 1865) are commonly found in the same mangrove habitat, where they experience frequent, acute fluctuations in temperature and salinity. Ecological studies indicate a temporal variation, including occasional absence, in the distribution of bothG. cylindrata andT. parva; this fed us to examine the physiological adaptations of the three species (collected at Western Bay, Twin Cays, Belize in 1985, 1986 and 1988). Each was subjected to acute, repeated exposure to either control (35 S) and decreased (25 S) salinity or to control and increased (45 S) salinity. Ability to regulate water and ion content (g H₂O or mol g^-1 solute free dry wt) was examinedA. viridari behaved as a hyperosmotic conformer at decreased salinity but as an osmoconformer at increased salinity. Regardless of direction of salinity change,A. viridari regulated water content through change in Na⁺, K⁺, and Cl^– contents. In contrast,G. cylindrata behaved as an osmoconformer and did not demonstrate ability to regulate water content.T. parva behaved as an osmoconformer, showed incomplete regulation of water content via change in Na⁺, K⁺, and Cl^– contents but had limited survival following exposure to 45 S. Each species was also exposed to change in temperature. Species were subjected to acute, repeated exposure either to control (28°C) and decreased (21°C) temperature or to control and inereased (35°C) temperatureA. viridari regulated water and ion content under both experimental conditions. In contrast,T. parva did not regulate water and ion content under either experimental temperature.G. cylindrata did not regulate water and ion content during exposure to decreased temperature and did not survive exposure to increased temperature. ForA. viridari, weight specific oxygen uptake rates (mg O₂ g^-1 ash-free dry wt) were determined. Exposure to decreased salinity or to increased temperature resulted in a small sustained elevation in O₂ uptake. It is concluded that, unlikeA. viridari, T. parva andG. cylindrata are only marginally adapted to withstand the salinity and temperature stresses, respectively, of the mangrove habitat. The inability ofT. parva andG. cylindrata to fully adapt to extremes in the mangrove habitat could well explain the temporal variation seen in the distribution of these two species.Contribution number 380. Caribbean Coral Reef Ecosystems, National Museum of Natural History, Smithsonian Institution     

Studies on the transport of sugars in the holothurian Holothuria scabra

Experiments using ¹⁴C sugars were carried out on the holothurian Holothuria scabra Jäger, in order to assess the role of its perivisceral fluid in the translocation and transportation of dissolved organic materials. The results obtained indicate that the perivisceral fluid plays a significant part. Rates of ¹⁴C glucose, fructose and sucrose uptake were followed in major tissues such as the alimentary canal, haemal system, respiratory tree and body wall. The monosaccharides are absorbed more intensively by digestive and haemal systems, the disaccharide by respiratory tree and body wall. It is, therefore, presumed that tissues in H. scabra selectively absorb sugars depending on their metabolic activity.     

Feeding ecology of a size-structured predator population,the South American sun-star Heliaster helianthus

Patterns of feeding in a population of Heliaster helianthus (Lamarck), a common and dominant species of starfish indigenous to the Pacific South American coast, were investigated in an intertidal habitat in central Peru from October 1986 to April 1987. The H. helianthus population comprised individuals of 3.5 to 30.2 cm body size (diameter) with two modal size classes. The number of rays ranged between 18 and 40, and individuals with 31 to 33 rays accounted for ca. 42% of the total population. There was a higher rate of increase in ray number with body size amongst small individuals(<13.0 cm diam). H. helianthus is capable of feeding on more than one prey item at a time (average of 5.6 to 13.2 prey items handled, with several predators observed to hold >100), and both the number of prey individuals captured and the total prey biomass were significantly correlated with predator size. Amongst a total of 1132 feeding observations, the largest number of predators (an average of 85.4% of those feeding) were preying on the mussel Semimytilus algosus whilst another mussel, Perumytilus purpuratus, ranked second with 21,9% of predators feeding. The proportion of S. algosus in the diet increased from 65.4% in the smallest predator size-group (10.9 cm diam) to 91.2% in the largest (19.0 cm). In contrast, P. purpuratus and barnacles were more highly represented in the diet of small H. helianthus. The smallest size-group (10.9 cm) had low dietary overlap with larger sizes and less specialized prey utilization. Two geographically separated populations of H. helianthus in Peru and Chile showed contrasting patterns of prey utilization. S. algosus and P. purpuratus comprised 85.5 and 6.5% by number in the diet of the Peruvian population, respectively, whilst corresponding figures for the Chilean population were 8.3 and 60.5%, with barnacles attaining a higher share (22.6%). However, the total number of prey individuals per feeding predator was almost the same in Peru and Chile, with 10.0 and 10.7 individuals, respectively. H. helianthus individuals of different sizes occupy slightly different microhabitats within the intertidal area, which, coupled with differential spatial distribution of prey species, results in the predator population being able to utilize a wide range of resources.     

Diet of four species of deep-sea isopods (Crustacea: Malacostraca: Peracarida) in the South Atlantic and the Southern Ocean

The food of four species of asellote isopods (Crustacea, Malacostraca), Haploniscus rostratus, Haploniscus unicornis, Acanthocope galatheae and Betamorpha fusiformis, was evaluated by analysis of their gut contents. The isopods were sampled at several stations on the abyssal plains of Guinea Basin, Angola Basin and Cape Basin (southeast Atlantic), the Weddell Sea abyssal plain and the Antarctic continental slope during the DIVA and ANDEEP expeditions in 2000, 2001 and 2005. While all species had mineral particles in their guts and mucus material was the most frequent food item, the remaining gut contents differed among species. Betamorpha fusiformis fed mostly on phytodetritus, especially in the Southern Ocean basins and ingested along with it whole calcareous foraminifers. Acanthocope galatheae showed some differences in gut contents between basins, but in the Guinea Basin, the contents were to a large extent stercomata, i.e., waste pellets of soft-walled foraminifers, i.e., the Komokiaceae. Indications were that the haploniscids were feeding on detritus and agglutinating foraminifers (stercomata). This indicates spatial differences in food availability for this diverse group of deep-sea isopods and the importance of poorly known foraminiferal groups, like the Komokiaceae, as a food source in the deep sea.     

Clonal and solitary anemones (Anthopleura) of western North America: population genetics and systematics

Francis (1979) proposed that clonal and solitary forms of the anemone Anthopleura elegantissima are actually two species. In 1984 and 1985, samples from two to six California populations of all known forms and species of California Anthopleura were analyzed electrophoretically to determine their taxonomic relationships. Data from 14 enzymes and 18 loci, 17 of them polymorphic, show that the two forms of A. elegantissima are virtually identical electrophoretically, and there is no evidence of reduced gene flow between them. We conclude there are three species of Anthopleura in California: A. elegantissima (Brandt, 1835), A. xanthogrammica (Brandt, 1835) and A. artemisia (Dana, 1848). Genetic variation in the two species capable of asexual reproduction, A. elegantissima and A. artemisia, is extremely high, approximately 2.5 times that of the strictly sexual A. xanthogrammica.     

Endofauna differences between two temperate marine sponges (Demospongiae; Haplosclerida; Chalinidae) from southwest Australia

The endofaunal assemblages associated with two species of sponge from the family Chalinidae (Haliclona sp. 1 and Haliclona sp. 2) were studied at four locations along the south west coast of Australia. The species have distinct morphologies and inhabit similar microhabitats; there is also considerable scientific interest in Haliclona sp. 1 (green Haliclona) due to the unique bioactive compound it produces. A total of 948 and 287 endofaunal individuals were found associated with 16 specimens of both the green Haliclona and Haliclona sp. 2 (brown Haliclona), respectively. Twenty-four endofaunal taxa were found (from mysid shrimps to teleost fish), with the brown Haliclona having a greater density of endofaunal species and individuals than the green Haliclona. The endofaunal assemblages of both species of sponge were significantly different, but only the endofaunal assemblage within the green Haliclona differed significantly among locations. Differences in the abundance and biomass of associated endofauna of each species of sponge can be related to differences in their morphologies, size and internal structure. In the green Haliclona, differences in endofaunal assemblages among locations are unlikely to be due to environmental influences as taxa discriminating each locations assemblage were common to both species of sponge. Numerous endofaunal individuals were found to be reproductively active, and it is clear that the species of sponge provide important habitats for their associated endofauna. This provision of habitat needs to be taken into account when harvesting green Haliclona biomass for supply of its target bioactive compound for further pharmaceutical development.     

Body size preferences in the pot-bellied seahorse <Emphasis Type="Italic">Hippocampus abdominalis:</Emphasis> choosy males and indiscriminate females

Male seahorses (genus Hippocampus) provide all post-fertilization parental care, yet despite high levels of paternal investment, these species have long been thought to have conventional sex roles, with female mate choice and male–male competition. Recent studies of the pot-bellied seahorse (Hippocampus abdominalis) have shown that sex-role reversal occurs in high-density female-biased populations, indicating that male mating preferences may lead to sexual selection on females in this species. Egg size, egg number, and offspring size all correlate positively with female body size in Hippocampus, and by choosing large mating partners, male seahorses may increase their reproductive success. While male brood size is also positively correlated with body size, small H. abdominalis males can carry exceptionally large broods, suggesting that the fecundity benefits of female preference for large partners may be limited. We investigated the importance of body size in reproductive decisions of H. abdominalis, presenting focal individuals of both sexes with potential mating partners of different sizes. Mating preferences were quantified in terms of time spent courting each potential partner. Male seahorses were highly active throughout the mate-choice trials and showed a clear behavioral preference for large partners, while females showed significantly lower levels of activity and equivocal mating preferences. The strong male preferences for large females demonstrated here suggest that sexual selection may act strongly on female body size in wild populations of H. abdominalis, consistent with predictions on the importance of female body size for reproductive output in this species. An erratum to this article can be found at