Depth analysis of fatty acids in two caribbean reef corals

Total fatty acid compositions of colonies of two hermatypic, reef-building corals collected during the day-time over a depth range of 21 m were determined to assess the effect of depth-related environmental factors upon the lipid content of these organisms. No systematic changes were found, suggesting a steady-state balance between algal and animal lipogenesis in these symbiotic partnerships. Stephanocoenia michelinii , a day and night feeder, contained lipids indicative of external dietary sources such as copepods, whereas Montastrea annularis , a night feeder, did not.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46632/1/227_2004_Article_BF00391131.pd

Bioirrigation in Marine Sediments

Bioirrigation refers to the enhanced transport of solutes across the sediment-water interface induced by the activities of bottom-dwelling organisms. This chapter provides an overview of what bioirrigation is, how it is induced, and how it affects processes in marine sediments. After discussing some well documented effects of bioirrigation such as the enhanced cycling of organic matter, nutrients, metals and pollutants, this article also touches upon phenomena that were uncovered more recently and deserve further attention, including rapid redox oscillations, bioadvection, and biohydraulic sediment cracking. Last but not least, some of the key methods used to study bioirrigation are presented, with special emphasis on imaging techniques that allow measurements with high spatial and temporal resolution. The chapter includes a number of graphics and videos that illustrate the highly dynamic and heterogeneous nature of bioirrigated sediments

Bioirrigation in Marine Sediments

Bioirrigation refers to the enhanced transport of solutes across the sediment-water interface induced by the activities of bottom-dwelling organisms. This chapter provides an overview of what bioirrigation is, how it is induced, and how it affects processes in marine sediments. After discussing some well documented effects of bioirrigation such as the enhanced cycling of organic matter, nutrients, metals and pollutants, this article also touches upon phenomena that were uncovered more recently and deserve further attention, including rapid redox oscillations, bioadvection, and biohydraulic sediment cracking. Last but not least, some of the key methods used to study bioirrigation are presented, with special emphasis on imaging techniques that allow measurements with high spatial and temporal resolution. The chapter includes a number of graphics and videos that illustrate the highly dynamic and heterogeneous nature of bioirrigated sediments

Population consequences of mutual attraction between settling and adult barnacles

1. Spatial patterns of recruitment were compared between populations of the rocky shore barnacles (Crustacea: Cirripedia) Semibalanus balanoides, an obligate cross-fertilizer, and Chthamalus montagui, which can self-fertilize. We tested the hypothesis that recruitment depends on a behaviourally mediated interaction at settlement between the effects of adult background density and adult spacing, which limit free space for settlement and mating opportunities, respectively. Recruitment to patches of cleared rock (10- or 30-cm diameter) was compared between replicate shores with background densities of adult barnacles classed as low (?20 per 25 cm2) and high (>4× low). Replicate patches were cleared of all barnacles surrounding a remnant cluster, comprising 0, 1, 2, 4, 8, 16 or 32 adults.2. For S. balanoides, settlement and subsequent recruitment over 5 months varied in direct proportion to remnant cluster size, except on the shore with the highest background density where recruitment was inversely proportional to cluster size. We interpret this inversion to indicate attraction to potential mates at low adult densities (positive density dependence, an Allee effect) switching to attraction to free space at high density (negative density dependence). The strengths and slopes of the regressions increased from shores with the lowest to the highest overall recruitment of barnacles, but retained significance over a five-fold range in recruitment. Positive effects of cluster size on recruitment were consistent between consecutive years, despite considerable variation in recruitment densities. In contrast, recruitment of C. montagui was generally more weakly proportional to cluster size, except for a strong positive correlation at the shore with the highest recruitment.3. Dispersion of recruits within treatment patches was accurately modelled by a computer simulation that allowed each barnacle to settle at random between fixed minimum and maximum distances from the nearest other settled barnacle. The model estimated threshold distances by maximum likelihood fit to observed recruitment into concentric annuli around the central adult cluster. Upper thresholds of separation corresponded to penis length for 65% of S. balanoides and 42% of C. montagui patches. Lower thresholds were ?2× cyprid length for 75% of S. balanoides patches, but were larger than this for C. montagui patches