Central East Coast Research Articles

SHOREWARD SAND TRANSPORT OUTSIDE THE SURFZONE, NORTHERN GOLD COAST, AUSTRALIA

To date, no suitable theoretical basis has been derived to predict with reliable accuracy the shoreward sand transport under waves in the deeper water outside the surf zone. This is important for understanding the rate of recovery of beaches after major storm erosion and, in some circumstances, to quantify net shoreward supply of sand to the shoreline from the active lower shore-face below the depth of storm erosion bar development. Even a relatively low rate of long term shoreward net supply may contribute to shoreline stability where it offsets a gradient in the longshore sand transport that would otherwise lead to recession. This paper outlines the results of analysis of a 41 year dataset of beach and nearshore profile surveys to quantify annual average rates of shoreward net sand transport in 6-20m water in an area where the profiles are not in equilibrium due to the existence of a residual river mouth ebb delta bar lobe. Additionally, an empirical adaptation of the sheet flow relationship of Ribberink and Al-Salem (1990) to provide for the effects of ripples has been derived from large wave flume data and correlates well with the measured Gold Coast transport rates. These have been applied to a new coastline modelling system developed as part of research into the long term evolution of Australia’s central east coast region in response to sea level change and longshore sand transport processes, which combines the one-line concept of shoreline profile translation within the zone of littoral sand transport with cross-shore profile evolution across the deeper shore-face profile below that zone. It demonstrates the importance of providing for both the shoreward supply from the continental shelf and the varying profile response time-scale across the shore-face in predicting shoreline evolution.

The influence of riverine barriers on phylogeographic patterns of Malagasy reed frogs (Heterixalus)

We analyzed the influence of large rivers on the phylogeography of endemic widespread amphibians along Madagascar’s east coast, using as models various species and species complexes of Malagasy reed frogs (Heterixalus spp.) that are specialized to either highland or lowland habitats. We assembled a dense sampling across the full species ranges and used mitochondrial (cob) as well as nuclear (Rag-1) DNA sequences to assess their phylogeographies. A multigene mtDNA phylogeny of each species was constructed to establish the relationships among the main phylogroups, in order to understand the geographical regions of clade origins and possible directions of historical range expansions. Distinct intraspecific lineages as diagnosed by mitochondrial haplotype clades were found in highlands and lowlands. Most geographical boundaries among these phylogroups did not coincide with rivers, indicating that the influence of rivers on the primary divergence of phylogroups is probably minor in these frogs. Nevertheless, we found evidence for the influence of one riverine barrier in the lowland species complex, where the most important genetic discontinuity (the border between Heterixalus madagascariensis and H. alboguttatus) coincides with the geographical position of the Mangoro River on Madagascar’s central east coast. Analyses of the highland species H. betsileo revealed the existence of six deep haplotype lineages, separated in two major subpopulations which differ largely in altitudinal distribution and do not overlap with the geographical settings of rivers in the highlands. Furthermore, our analyses indicated that most of the major intraspecific lineages of reed frogs show signs of a rather recent population expansion.

Speciation of Co, Ni and Cu in the coastal and estuarine sediments: Some fundamental characteristics

Kinetic and sequential extraction methods were used to investigate chemical speciation and distribution of Co, Ni, and Cu in the estuarine and coastal sediments collected from the central east coast of India. The kinetic (single) extraction study provided a chemically significant description of the kinetics of metals–sediment interactions and correctly predicted the influences of ligand field stabilization energy (LFSE) and water exchange rate (k-w) on the dissociation rate constants of metals–sediments complexes in the natural systems. The results consistently demonstrate that the fast (kd1) and medium fast (kd2) dissociation rate constants of the 3d transition metals complexes in the estuarine and coastal sediments follow the trend as predicted from the LFSEs (weak field) (kd 1,2,Co(II) d7>kd 1,2, Ni(II) d8>kd 1,2, Cu(II) d9). However, a higher rate coefficient of water exchange (k-w) of Cu (II) helps them to form more strong inert complexes than predicted from its LFSE alone. Sequential extraction method was used to fractionate these metals depending upon their association with different phases in the studied sediments. The comparison and statistical analysis of the fractionation data obtained by two independent methods indicate that the transition metals formed strong complexes with the organic matter present in the sediments. However, Cu undergoes strong complexation reaction with organic matter within the sediments followed by Ni and Co. This study suggests that the non-residual fractions (obtained from sequential extraction study) may overestimate the bioavailable fraction of metals in a system.

A study of lead and cadmium speciation in some estuarine and coastal sediments

Chemical speciation of lead (Pb) and cadmium (Cd) in the coastal and estuarine sediments along the central east coast of India was studied by applying sequential and kinetic extraction methods. The results of this study suggest that concentrations of non-residual and dynamic complexes (which are good indicators of bioavailability) of these toxic metals gradually increase with increasing total metal loading in sediments.Increase in bioavailability of these toxic metals with increasing total metals concentrations in the sediments can be a potential threat to benthic organisms and aquatic biota in the system. This study shows that total organic carbon (TOC) is one of the key factors which play a crucial role in controlling speciation of these toxic metals in sediments. However, distribution and speciation of these metals are influenced by their total metal loading and trace metal competitions rather than only TOC content in sediments.An attempt was made to identify the key factors which control speciation of these toxic metals in natural system and provides a better understanding to predict and control pollution of Pb and Cd in coastal and estuarine sediments.

Pattern of Recovery of the Goliath Grouper <I>Epinephelus itajara</I> Population in the Southeastern US

In the present study, we evaluate the past and current distribution and abundance of the atlantic goliath grouper, Epinephelus itajara (Lichtenstein, 1822), in coastal waters of the southeastern United States. The study is based on quantitative surveys conducted by us (n = 190) and the Florida Fish and Wildlife Conservation Commission's Artificial Reef Program (n = 505), coupled with semi-quantitative data submitted by volunteer divers to the Reef Environmental Education Foundation (n = 27,542) over the past 15+ yrs. The vast majority of the goliath grouper population is restricted to Florida waters. We found that the population of goliath grouper, after dramatic fishery-induced declines in the 1970s and 1980s, and eventual fishery closure in the 1990s, increased off southwest Florida in the mid-1990s, directly offshore of the high-quality mangrove nursery of the Ten Thousand Islands. It then expanded north and south, eventually increasing off Florida's central east coast. Tagged fish, regardless of life stage, showed strong site fidelity to home sites: juveniles (2963 tagged, 32.6% recaptured) to mangrove nursery sites and adults (2110 tagged, 7.6% recaptured) to offshore reefs. All long-distance movements appeared to be in response to approaching maturity, with juveniles emigrating from mangroves to take up residence on offshore reefs, to seasonal spawning activity, with adults moving from home sites to aggregation sites, or to apparent feeding sites in inlets. Understanding these patterns of population recovery and movement is fundamental to devising appropriate management policies.

A multi-method approach for the study of lanthanum speciation in coastal and estuarine sediments

Two independent analytical methods (sequential extraction and kinetic extraction methods) were applied in order to understand the distribution and speciation of La in the coastal and estuarine sediments from the central east coast of India. Sequential extraction study revealed that La was primarily present as inert complexes (~ 50–60% of the total La) in all the sediments. Amounts of ~ 20–30% of the total La in all the sediments were found to associate with the total organic carbon (TOC) in the sediments. The dissociation rate constants of La–sediment complexes obtained from kinetic extraction studies revealed that the concentration of thermodynamically weak complexes of La gradually increased with the increasing La/TOC ratio in the sediments. The results of this investigation demonstrate that combination of two analytical methods having complementary analytical capabilities can provide a better physicochemical picture of La speciation than either one of the method can do alone. Combination of the data obtained from sequential extraction and kinetic extraction methods suggest that TOC is one of the key factors in controlling speciation and distribution of La in the sediments.

Lacaziosis in bottlenose dolphins Tursiops truncatus along the coastal Atlantic Ocean, Florida, USA

This study represents the first systematic study of lacaziosis (lobomycosis) in bottlenose dolphins Tursiops truncatus in the Atlantic Ocean along the east-central coast of Florida, USA. Lacaziosis is a chronic infection of the skin caused by the fungus Lacazia loboi, which affects only dolphins and humans. Previous studies have shown a high prevalence (6.8 to 12.0%) of lacaziosis in resident dolphins from the adjacent Indian River Lagoon Estuary (IRL), where the disease is endemic. We examined the prevalence of lacaziosis in this coastal area using photo-identification data collected between 2002 and 2008 to determine the prevalence of lacaziosis in coastal dolphins using photographic methodology shown to have high sensitivity and specificity in prior research. The prevalence of skin lesions compatible with lacaziosis estimated from photographic data was 2.1% (6/284), approximately 3 times lower than that described for the estuarine population using similar methods. To exclude potential bias introduced by differences in study duration and survey effort among areas, an 18 mo period when effort was most equal (January 2006 to June 2007) was chosen for statistical comparison. The prevalence of lacaziosis estimated from photographic data was significantly lower (3.8%: n = 6/160) in the Atlantic Ocean compared to the IRL (12.0%: n = 20/167) (risk ratio = 3.19, 95% CI 1.32 to 7.75, p < 0.01 by chi-square analysis). The lower prevalence of lacaziosis in dolphins found in the Atlantic Ocean and the overall lack of movement of dolphins between these habitats suggests that environmental conditions within the estuary may favor viability of L. loboi, and/or that immune compromise in resident estuarine dolphins is a precursor to the disease.

Two syntopic and microendemic new frogs of the genus Blommersia from the east coast of Madagascar

We describe two new species of semiarboreal frogs from the northern central east coast of Madagascar which occur syntopically, at least on the island of Nosy Boraha. The two species are morphologically closest to Blommersia wittei, but differ in advertisement calls and molecular phylogenetic relationships. One of the new species has a remarkable femoral gland structure, as these are shifted towards the distal part of the thigh, close to the knee joint. The new species are apparently microendemic to a small stretch of Madagascar's east coast and have so far not been found at higher elevations. Since both new species are tolerant of habitat disturbance and occur in anthropogenically altered habitats, such as plantations and villages, we propose an IUCN threat status of Least Concern despite their restricted extent of occurrence.

Constraining Holocene lake levels and coastal dune activity in the Lake Michigan basin

Sediment cores collected from embayed lakes along the east-central coast of Lake Michigan are used to construct aeolian sand records of past coastal dune mobility, and to constrain former lake levels in the Lake Michigan basin. Time series analysis of sand cycles based on the weight-percent aeolian sand within lacustrine sediment, reveals statistically significant spectral peaks that coincide with established lake level cycles in Lake Michigan and the Gleissberg sunspot cycle of minima. Longer cycles of ~ 800 and ~ 2200 years were also identified that correspond to solar cycles. Shorter cycles between 80 and 220 years suggest a link between coastal dune mobility, climate, and lake levels in the Lake Michigan basin. Radiocarbon-dated sedimentary contacts of lacustrine sediment overlying wetland sediment record the Nipissing transgression in the Lake Michigan basin. Lake level rise closely mimics the predicted uplift of the North Bay outlet, with lake level rise slowing when outflow was transferred to the Port Huron/Sarnia outlet. The Nipissing highstand was reached after 5000 cal (4.4 ka) BP.

New spider mite genus (Prostigmata: Tetranychidae) from Australia &amp;amp; New Zealand, with a discussion of Yezonychus Ehara

The concept of Yezonychus Ehara is revised. A new genus, Neonidulus, is erected to accommodate four species: N. cornus (Pritchard &amp; Baker), N. falsicornus (Zhang &amp; Martin) and N. brevipilus (Zhang &amp; Martin) from New Zealand, and a new species described from the central east coast of Australia, N. tereotus.

Variability of SeaWiFS-derived chlorophyll-a concentrations in waters off central east coast of India, 1998–2003

Seasonal and inter-annual variability in satellite-derived estimates of near-surface chlorophyll-a concentration off the central east coast of India from 1998 to 2003 is examined. Wind-induced upwelling predominates in late spring and winter, coinciding with the maximum in solar radiation, leading to increased accumulations of phytoplankton biomass. Chlorophyll concentrations varied from 2 to 10mg/m3 over the central east coast of India and were generally lower in June and maximal in March. Chlorophyll concentrations along the coast followed a similar seasonal pattern (ranging from 0.5 to 6mg/m3); however, concentrations were always greater on the Machilipatnam and Nellore compared with the Visakhapatnam and Chennai. The lack of upwelling favorable conditions results in the majority of the southern side of the central east coast of India waters being insufficient, which is reflected in low or moderate productivity. The possible reasons and observed correlations between chlorophyll-a and upwelling index during the study period was discussed.

Interpretation of ground and aeromagnetic surveys of Palmer Land, Antarctic Peninsula

Aeromagnetic data for Palmer Land provide new information on crustal structures of the Antarctic Peninsula. Features shown on the compilation of the Lassiter Coast and Orville Coast are characterized by systems of subparallel regional anomaly zones and lineaments. The magnetic data reveal the widespread presence of an orthogonal pattern of crosscutting linear discontinuities that can be interpreted as a Late Cretaceous/Early Tertiary fracture pattern. The main displacements in the anomaly pattern between the two units are recognized in Wetmore-Irvine glaciers area where the structure of the Antarctic Peninsula changes orientation from SW-NE to S-N. The NW-SE trending transitional zone is probably a transfer zone associated with north-westerly movement of the Lassiter Coast crustal segment relative to the Orville Coast segment. Within the Lassiter Coast a fragment of Pacific Margin Anomaly (PMA), Central Plateau Magnetic Anomaly and East Coast Magnetic Anomaly (ECMA) are mapped. Two-dimensional modelling suggests that PMA is caused by a limited depth body (8 km) consisting of numerous plutons, probably, of different ages, composition and magnetization. The Central Plateau Magnetic Anomaly and the Merrick-Sweeney-Latady zone of the Orville Coast are represented by strong positive anomaly bands that are associated with gabbro-diorite rocks and accompanying plutons intruded near by the border of Mount Poster Formation and Latady Formation. The ECMA are alignments of high-amplitude magnetic anomalies caused by gabbro-diorite bodies, which are located within the framework of the Cretaceous granite-granodiorite plutons. Granite-granodiorite plutons of Lassiter Coast Intrusive Suite are mostly reflected by positive anomalies (100-500 nT). Modelling studies and the character of distribution of the magnetic anomalies suggest that the plutons of Lassiter Coast Intrusive Suite are prominently reflected in magnetic anomalies of regional extent. The plutonic activities during the geological evolution of Palmer Land have been a more important process than what is apparent from rock outcrops. Magmatic activity abruptly diminished westward from the Behrendt Mountains apparently due to a modification of the crustal structure of the Antarctic Peninsula. The area between the Evans Ice Stream and the Behrendt Mountains is possibly underlain by the non-magnetic equivalent of the Haag Nunataks basement, similar to that which has been inferred for the Ellsworth Mountains.

Growth rates of juvenile green turtles Chelonia mydas from three ecologically distinct foraging habitats along the east central coast of Florida, USA

A generalized additive mixed modeling approach was used to assess somatic growth for juvenile green turtles Chelonia mydas at 4 sites in 3 ecologically distinct foraging habitats along the east central coast of Florida, USA. The 3 habitats were a man-made nuclear submarine turning basin (Trident Submarine Basin), an estuary (Indian River Lagoon), and oceanic sabellariid worm rock reefs (Sebastian Inlet and St. Lucie Power Plant). Turtles from the Indian River Lagoon site grew significantly faster than turtles from the Trident Submarine Basin and sabellariid worm rock reef sites. There were no significant differences in growth rates between the sabellariid worm rock reef and Trident Submarine Basin sites. Non-monotonic or dome-shaped growth rate functions reflecting an immature peak in growth rates were observed for all 3 habitats. Growth rates peaked in 1998 for turtles in the Trident Submarine Basin and sabellariid worm rock reef habitats; since then growth rates have declined. This temporal decline in growth rates may reflect density-dependent effects on growth as more juveniles recruit to Florida for aging grounds, a direct result of increases in nest production at the primary rookeries (Costa Rica, Florida and Mexico). Developmental habitats are important for the survival of juvenile marine turtles. This study illustrates the degree to which juvenile growth rates vary among developmental habitats, which ultimately can affect the rate of growth and recovery potential of nesting stocks.

Using lidar remote sensing and support vector machines to classify fire disturbance legacies in a Florida oak scrub landscape

Abstract Background/Question/Methods Ecologists have long emphasized the reciprocal interactions between spatial pattern and ecological processes in the creation of landscape mosaics. While an enormous amount of recent research has focused on the quantification of spatial patterns, efforts to infer process from pattern have been hindered by the presence of multi-scale, often confounding, drivers of pattern in many landscapes. At the mesoscale, Holling’s extended keystone hypothesis posits that spatially contagious disturbances such as fire are the dominant pattern-generating processes. To test this hypothesis, we used fire history data and discrete, small-footprint lidar remote sensing acquired over a 22 sq. km landscape of oak scrub in the Kennedy Space Center/Merritt Island National Wildlife Refuge area on the east-central coast of Florida. We binned the lidar return data into 1 m vertical height intervals for each 5 m x 5 m horizontal cell. Since community structure tends to recover by 7 years post-fire, we tested for significant differences between recently-burned (&lt; 7 years) and unburned (≥ 7 years) patches with multivariate analysis of variance. To predict the burn status of each cell, we then used distribution-free, nonlinear support vector machine (SVM) classifiers, which have proven to be highly accurate for complex pattern recognition problems. Results/Conclusions We detected statistically significant differences in vegetation structure between burned and unburned patches for all of the dominant land cover types (upland non-forested, upland forested, wetland hardwood forest, and non-forested wetlands) in the study area. Initially, we obtained a predicted error rate of approximately 34% from the SVM classifier; by averaging the binned lidar data over a moving window of increasing size, however, we achieved substantial reductions in the predicted error rate for the SVM classifier. The optimal window size of 100 m x 100 m yielded a predicted misclassification rate of approximately 3%, an order of magnitude lower than the error rate obtained on the same data using a logistic regression classifier. These results suggest that, as predicted by the extended keystone hypothesis, fire disturbance is a dominant pattern-generating process at the patch scale in this oak scrub landscape. Furthermore, these results indicate that it is possible to use vertical vegetation structure, as represented by the binned lidar data, to predict burn status with a high level of accuracy. While our study employed a simple binary classification scheme, future research will focus on using SVM regression techniques to predict burn status with finer-grained classes of time since fire.

Using lidar remote sensing and support vector machines to classify fire disturbance legacies in a Florida oak scrub landscape

Ecologists have long emphasized the reciprocal interactions between spatial pattern and ecological processes in the creation of landscape mosaics. While an enormous amount of recent research has focused on the quantification of spatial patterns, efforts to infer process from pattern have been hindered by the presence of multi-scale, often confounding, drivers of pattern in many landscapes. At the mesoscale, Holling’s extended keystone hypothesis posits that spatially contagious disturbances such as fire are the dominant pattern-generating processes. To test this hypothesis, we used fire history data and discrete, small-footprint lidar remote sensing acquired over a 22 sq. km landscape of oak scrub in the Kennedy Space Center/Merritt Island National Wildlife Refuge area on the east-central coast of Florida. We binned the lidar return data into 1 m vertical height intervals for each 5 m x 5 m horizontal cell. Since community structure tends to recover by 7 years post-fire, we tested for significant differences between recently-burned (< 7 years) and unburned (≥ 7 years) patches with multivariate analysis of variance. To predict the burn status of each cell, we then used distribution-free, nonlinear support vector machine (SVM) classifiers, which have proven to be highly accurate for complex pattern recognition problems. We detected statistically significant differences in vegetation structure between burned and unburned patches for all of the dominant land cover types (upland non-forested, upland forested, wetland hardwood forest, and non-forested wetlands) in the study area. Initially, we obtained a predicted error rate of approximately 34% from the SVM classifier; by averaging the binned lidar data over a moving window of increasing size, however, we achieved substantial reductions in the predicted error rate for the SVM classifier. The optimal window size of 100 m x 100 m yielded a predicted misclassification rate of approximately 3%, an order of magnitude lower than the error rate obtained on the same data using a logistic regression classifier. These results suggest that, as predicted by the extended keystone hypothesis, fire disturbance is a dominant pattern-generating process at the patch scale in this oak scrub landscape. Furthermore, these results indicate that it is possible to use vertical vegetation structure, as represented by the binned lidar data, to predict burn status with a high level of accuracy. While our study employed a simple binary classification scheme, future research will focus on using SVM regression techniques to predict burn status with finer-grained classes of time since fire.

Mixing, hypersalinity and gradients in Hervey Bay, Australia

Hervey Bay, a large coastal embayment situated off the central eastern coast of Australia, is a shallow tidal area (average depth = 15 m), close to the continental shelf. It shows features of an inverse estuary, due to the high evaporation rate (approx. 2 m/year), low precipitation (less than 1 m/year) and on average almost no freshwater input from rivers that drain into the bay. The hydro- and thermodynamical structures of Hervey Bay and their variability are presented here for the first time, using a combination of four-dimensional modelling and observations from field studies. The numerical studies are performed with the Coupled Hydrodynamical Ecological Model for Regional Shelf Seas (COHERENS). Due to the high tidal range (>3.5 m), the bay is considered as a vertically well-mixed system, and therefore, only horizontal fronts are likely. Recent field measurements, but also the numerical simulations, indicate characteristic features of an inverse/hypersaline estuary with low salinity (35.5 psu) in the open ocean and peak values (>39.0 psu) in the head water of the bay. The model further predicts a nearly persistent mean salinity gradient of 0.5 psu across the bay (with higher salinities close to the shore). The investigation further shows that air temperature, wind direction and tidal regime are mainly responsible for the stability of the inverse circulation and the strength of the salinity gradient across the bay. Due to an ongoing drying trend, the occurrence of severe droughts at the central east coast of Australia and, therefore, a reduction in freshwater supply, the salinity flux out of the bay has increased, and the inverse circulation has also strengthened.

Two New Species of Nephasoma (Sipuncula: Golfingiidae) from the Western Atlantic Ocean

Abstract Two new species of the genus Nephasoma, phylum Sipuncula, are described from subtropical waters of the western Atlantic. Nephasoma (Nephasoma) columbaris is described from the central east coast of Florida where it is found along the edge of the continental shelf at depths of 61 to 104 m associated with the rubble from the reefs of the deep water coral Oculina varicosa. A second species, Nephasoma (Nephasoma) ditadii, is described from Brazilian waters in sand habitats at 150 m on the continental shelf off the coast of the state of Sao Paulo. Morphology of the two species is compared with allied species in the genus and the phylum. Usage in the taxonomic literature of the diagnostic characters “shield” and “pseudoshield” is reviewed and evaluated.

Retracted: ENSO‐related modulation of coastal upwelling along the central east coast of India

AbstractAn index of El Niño Southern Oscillation (ENSO) in the Pacific during February through April is shown to account for a significant part of the variability of coastal sea surface temperature (SST) anomalies measured a few months later within the central east coast of India (CEI). This ENSO‐related modulation of coastal upwelling appears to contribute to the connection observed at the basin‐scale between ENSO and SST in the Bay of Bengal. The ability to use this teleconnection to give warning of large changes in the CEI a few months in advance is exemplified using data 1998–1999 ENSO events. Copyright © 2008 Royal Meteorological Society

Stress tolerance of a subtropical Crassostrea virginica population to the combined effects of temperature and salinity

The combination of salinity and temperature has synergistic effects on virtually all aspects of the biology of estuarine organisms. Of interest were site-specific characteristics in the response of the eastern oyster, Crassostrea virginica, from the St. Lucie River Estuary to the interactive effects of temperature and salinity. This estuary, one of the largest on the central east coast of Florida, is strongly influenced by anthropogenic modifications due to management needs to control the patterns of freshwater flow in the St. Lucie River watershed. Crassostrea virginica is designated a valued ecosystem component for monitoring the health of this estuary. Our approach used a multidimensional response surface design to study the effects of temperature and salinity on sublethal measures of oyster performance: (1) body condition index as an overall indicator of bioenergetic status and (2) the RNA/DNA ratio as a biochemical indicator of cellular stress. The results showed that there was a greater ability to withstand extreme salinity conditions at lower temperatures. However, there were no site-specific attributes that differentiated the response of the St. Lucie Estuary population from populations along the distribution range. Condition index was a less variable response than the RNA/DNA ratio, and the final models for mean condition index and the RNA/DNA ratios explained 77.3 and 35.8% of the respective variances.

Molecular-genetic analyses of dispersal and breeding behaviour in the Australian termite Coptotermes lacteus: evidence for non-random mating in a swarm-dispersal mating system

We used microsatellite DNA markers to infer the dispersal and breeding behaviour of Coptotermes lacteus, a termite whose large mounds are a conspicuous feature of Australia’s central east coast. We genotyped a subsample of neuter offspring for each of 38 colonies sampled over two spatially separated populations, one in a natural forest and the other in an exotic radiata pine plantation. All colonies showed offspring genotype frequencies consistent with a single reproductive pair. This result confirms that stable monogamy is the normal breeding arrangement for this species and that multi-reproductive colonies are rare. The two study populations were significantly differentiated and the distance separating them (~150 km) is therefore an effective constraint on gene flow. The populations themselves, however, were not noticeably subdivided above the level of colony. This lack of within-population viscosity is unexpected for weakly dispersing species and suggests that local gamete dispersal is in fact quite effective in C. lacteus. Nonetheless, dispersing sexuals do not appear to mate randomly. Instead, all four microsatellite loci are deficient in heterozygotes, indicating that populations are substantially inbred, irrespective of habitat. Evidence from hierarchical F-statistics, spatial genetic autocorrelation and relatedness calculations suggests that deviations from Hardy–Weinberg equilibrium may result from either a preference for non-sibling relatives over totally unrelated mates, or from random mating with viscosity – though evidence for the latter hypothesis was not detected. These findings suggest that swarm-dispersal mating systems, usually considered to produce outbreeding and panmixia, can instead involve a notable degree of non-random mating.