Temporal Patterns Of Settlement Research Articles

Spatial and temporal settlement patterns of blue crab (Callinectes sapidus and Callinectes similis) megalopae in a drought-prone Texas estuary

The Mission-Aransas Estuary is the wintering ground for the only sustained wild population of the endangered whooping crane (Grus americana), and blue crabs (Callinectes sapidus) are an important component of their diet as well as being a major food source for important sport fishes such as the red and black drum. Blue crabs also support a commercial crabbing industry, and fisheries data indicate that blue crab populations have been declining since the 1980s. Possible factors leading to decline in blue crab populations include overfishing, increased populations and predation by regulated sport fishes, reduced freshwater inflows into estuaries, and reduced larval recruitment. Little is known about blue crab recruitment dynamics in this region, but restricted passes between coastal estuaries and the Gulf of Mexico along with extended periods of drought that often lead to hypersaline conditions in coastal bays may limit larval recruitment from the Gulf into the bays. To investigate blue crab larval recruitment patterns, citizen scientist volunteers used hogshair settlement collectors to sample five monitoring sites over a four year period. Results show that large numbers of blue crab megalopae are common in nearshore waters of the Gulf of Mexico, but only a small fraction (∼1%) recruit into the estuary. Peak periods of ingress into the estuary occur during fall and winter months, with C. sapidus primarily contributing to the fall peak and C. similis dominating the winter peak. Increased salinity in the estuary during droughts may reduce the ability of blue crab larvae to detect and enter passes into the estuary.

Spatial and temporal patterns of settlement among juvenile inshore fishes of Eastern Adriatic Sea, Croatia

Spatial and temporal patterns of settlement among juvenile inshore fishes of Eastern Adriatic Sea, Croatia

Settlement length and temporal settlement patterns of juvenile cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and whiting (Merlangius merlangus) in a northern North Sea coastal nursery area

Abstract Knowledge of settlement timing and duration, which has been identified as an important milestone for demersal fish, is critical to understanding population connectivity, relevant to the development of spatially—and temporally—resolved conservation measures, and recruitment variability, as important density-dependent dynamics may take place at this stage. To study the settlement ecology of cod haddock, and whiting, sampling was conducted over spring and summer 2004–2006 at the northern North Sea nursery area. Over 4000 0-group juveniles were collected. Settlement was associated with clear and progressive changes in the prey composition of these juveniles. The size of fish that could be considered settled was estimated as 49 (±3) mm for cod, 78 (±4) mm for haddock, and 85 (±6) mm for whiting. Clear differences in temporal settlement patterns were also apparent. Cod settled in a single pulse lasting about a month (mid-May to mid-June) and initially occupied shallower, inshore waters, whereas haddock settled in one pulse, lasting ∼2 weeks (second half of May), favouring deeper, farther offshore locations. Whiting settled much later in the season and over a more protracted period (early June to early August), and their depth preferences also changed over time and with increasing length.

Temporal patterns of settlement, recruitment and post-settlement losses in a rocky reef fish assemblage in the South-Western Mediterranean Sea

Post-settlement events can significantly alter the density distribution of settlers and subsequently the adult population structure. The temporal and inter-annual variability of settlement and the effects of mortality on recruitment were investigated across 2 years in the vicinities of Cabo de Palos–Islas Hormigas Marine Reserve by visual census and light trap sampling. Settlement was seasonal with greater species richness and abundance in summer. Although temporal synchronization was observed between larval supply and settlement, densities of settlers could not be predicted from post-larval abundances. Timing of settlement was consistent between years but with high inter-annual variation in abundance. High mortality (~80 %) and general decoupling between post-larval and settlement stages suggest that early mortality is driving such patterns. Nevertheless, indications of habitat-mediated mortality were found for benthic species such as Symphodus and Diplodus, highlighting the importance of habitat in shaping population demography.

Daily patterns of settlement and individual growth rates of young-of-the-year of the rockfish Sebastes inermis in a Sargassum bed

Otolith microstructure analysis was used to reveal the temporal patterns of settlement, planktonic duration and size-at-settlement (SAS) of young-of-the-year (YOY) of the rockfish Sebastes inermis in a Sargassum bed in Sendai Bay, northern Japan, during 2000 and 2001. Individual growth rates (IGR) during the planktonic period and after settlement for each settled group were also studied and compared to those of YOY collected in a Zostera marina bed. In both years, YOY settled in distinctive groups at new and full moon phases. SAS was surprisingly invariant (21.4–22.7 mm total length) while planktonic duration varied widely (range: 73–123 days), even within settlement groups and between years (mean = 88 days in 2000; mean = 105 days in 2001). In both years, IGR were remarkably lower during the planktonic period (range: 0.09–0.29 mm/d) than after settlement (range: 0.54–0.73 mm/d), demonstrating that Sargassum and Zostera marina beds are important nursery grounds for S. inermis. In conclusion, the analysis of variation in SAS vs planktonic duration along with the selection pressures on settlement size, were the most important driving factors in the settlement dynamics of this rockfish.

Nutrient enrichment affects recruitment of oysters and barnacles in a mangrove forest

We tested the hypothesis that nutrient enrichment affects recruitment of the oyster Sac- costrea glomerata and the barnacle Hexaminius popeiana, which are dominant occupiers of space on tree trunks in temperate mangrove forests in New South Wales, Australia. We measured recruitment on artificial settlement plates at high and low intertidal levels under ambient conditions and where we manipulated nutrient levels by adding fertiliser to the water column for 2 mo. To determine whether nutrients influenced temporal patterns of settlement and early mortality of larvae, we quan- tified recruitment for 2 sampling intervals: on plates that were replaced 4 times at 2 wk intervals and on those left in the field for the entire 2 mo. For both intervals, recruitment of oysters was 3 to 4 times and significantly higher under elevated than ambient nutrient conditions. Recruitment of barnacles was also significantly higher under elevated nutrient conditions, but only on plates sampled at 2 wk intervals. On plates left out for 2 mo, the effect of nutrients on recruitment was variable, but recruits were generally higher in number under ambient conditions, suggesting that nutrients might enhance postsettlement mortality. Nutrient enrichment clearly affected recruitment of oysters and barnacles, possibly by mimicking natural settlement cues of conspecific individuals. Considering the central role of recruitment to the population dynamics of marine benthic invertebrates, nutrient enrichment has the potential to alter species assemblages in estuarine and marine habitats.

Critical swimming speeds of late-stage coral reef fish larvae: variation within species, among species and between locations

The swimming abilities of larval fishes are important for their survival, potentially affecting their ability to avoid predators, obtain food and control dispersal patterns. Near settlement swimming abilities may also influence spatial and temporal patterns of recruitment. We examined Critical speed (U-crit) swimming ability in late stage larvae of 89 species of coral reef fishes from the Great Barrier Reef and the Caribbean. Coefficients of variation in U-crit calculated at the individual level were high (28.4%), and this was not explained by differences in size or condition factor of these same larvae. Among species U-crit ranged from 5.5 cm s−1 to 100.8 cm s−1 (mean=37.3 cm s−1), with 95% of species able to swim faster than the average current speed around Lizard Island, suggesting that most species should be capable of influencing their spatial and temporal patterns of settlement. Inter-specific differences in swimming ability (at both the family and species levels) were significantly correlated with size and larval morphology. Correlations were found between swimming performance and propulsive area, fineness ratio and aspect ratio, and these morphological parameters may prove useful for predicting swimming ability in other taxa. Overall, the swimming speeds of larvae from the same families at the two locations were relatively similar, although the Lutjanidae and Acanthuridae from the Caribbean were significantly slower than those from the great barrier reef. Differences in swimming speed and body form among late stage larvae suggests that they will respond differently to factors influencing survival and transport during their pelagic phase, as well as habitat use following settlement.

Environmental influences on temporal patterns of settlement in two littoral labrid fishes in the Mediterranean Sea

Correlations between daily fish settlement and environmental and physical parameters were examined during two consecutive years in two labrid species ( Symphodus roissali and Symphodus ocellatus) in the NW Mediterranean Sea. Both these species have a short planktonic larval duration (12±0.3 and 9±0.4 days, respectively) and limited offshore larval dispersal. Time-series analysis was used to compare the daily settlement patterns with various environmental variables, and non-linear generalized additive models (GAM) were used to examine the relationship between environmental conditions averaged over larval period and daily settlement patterns. Settlement was not uniform and took place as pulses of different length. Although the analyses detected a few significant correlations between day-to-day patterns in environmental variables and settlement (e.g. solar radiation, atmospheric pressure, daytime or nocturnal wind components), these were not consistent among years. In S. ocellatus, however, wind components (daytime or nighttime) explained part of the variance in settlement intensity. The correlations (GAM outputs) observed between settlement patterns and environmental variables (averaged during the whole planktonic period) suggest that calm weather during the planktonic period usually increases settlement success.

Temporal settlement patterns of larvae of the broadcast spawning reef coral Favites chinensis and the broadcast spawning and brooding reef coral Goniastrea aspera from Okinawa, Japan

The faviid corals, Favites chinensis and Goniastrea aspera are widely distributed in the Indo-Pacific region. Both corals are hermaphroditic broadcast spawners, but G. aspera is also known to brood planula larvae in Okinawa. This study investigated the temporal settlement patterns of planula larvae of the scleractinian corals F. chinensis and G. aspera that developed from spawned gametes, and planula release and settlement of brooded larvae of G. aspera from Okinawa, Japan. Some of the broadcast-spawned larvae of F. chinensis and G. aspera had very short pre-competency periods of 1–2 and 2–3 days after spawning, and relatively long maximum settlement-competency periods of 56–63 and 63–70 days after spawning, respectively. These pre-competency periods are among the shortest reported for larvae of broadcast spawning coral species, and appear to be negatively correlated with seawater temperature. F. chinensis larvae tended to settle rapidly with 34–39% of larvae settling in the first week after spawning, while broadcast-spawned G. aspera larvae had a slower settlement pattern with 11–15% of larvae settling in the first week after spawning. Brooded larvae of G. aspera settled more rapidly, with settlement rates of 27–31% within the first 24 h and 45–65% within the first week after the start of the experiment. The production of planula larvae with rapid settlement capabilities may enable F. chinensis and G. aspera to establish and maintain populations in shallow reef sites at Okinawa. The release of the brooded planulae for up to 2 months may explain why G. aspera is locally more dominant on shallow reefs in Okinawa than F. chinensis. On a broader scale, the longer settlement competency periods of some of the broadcast-spawned larvae of these species increase their potential for longer-distance dispersal and may partly explain the wide biogeographic distribution of these species in the Indo-Pacific region.

Timing of Parturition, Planktonic Duration, and Settlement Patterns of the Black Rockfish, Sebastes inermis

The microstructure of otoliths was used to examine the relationship among timing of parturition, duration of planktonic stage, and temporal patterns of settlement in young-of-the-year (YOY) Sebastes inermis collected during the settlement seasons of 1998–2001 in a seagrass bed at the northwestern coast of Japan. Parturition occurred in winter, predominantly around the new and full moons, and parturition dates were distributed mainly from early January to late February. In the 4 years YOY S. inermis settled into distinctive groups at early spring, synchronized mainly to a semi-lunar cycle at new and full moon phases; except for 1998, in which settlement occurred around the first and third quarter moons. In all years settlers extruded earlier in the parturition season encompassed the first settlement groups that appeared in the bed and vice versa. Planktonic period ranged from 53 to 113 days, and its mean values varied significantly among settlement groups and years. Mean size at settlement showed less variability among settled groups and between years (range: 18–26 mm total length), which suggested an ideal size for settling and active migration. On the basis of our findings we discuss the extent to which the 'tidal control', 'settlement linkage', and 'competent size' hypotheses explain the temporal pattern of settlement.

Inter-cohort differences in spatial and temporal settlement patterns of young-of-the-year windowpane ( Scophthalmus aquosus) in southern New Jersey

The timing and location of settlement of two cohorts (spring and fall) of windowpane ( Scophthalmus aquosus) were identified based on collections from 64 sampling locations along a corridor from the lower estuary, through the inlet, and on to the adjacent inner continental shelf in southern New Jersey. Spatio-temporal patterns of settlement during 1989–1998 were determined based on capture location and timing, and eye migration stage. Spring-spawned windowpanes were collected in estuarine, inlet and ocean habitats as larvae, during settlement, and after settlement. Densities of spring-spawned larvae (∼2–10 mm standard length (SL)) peaked in May in all habitats (estuary, inlet, and ocean). Initial settlement of spring-spawned windowpane occurred during May in the inlet and ocean when fish had grown to ∼7–8 mm SL (mid-point of eye migration), but fish did not appear in demersal estuarine collections until June when they were larger and more developmentally advanced (∼24–32 mm SL; post-eye migration). A transitional settlement period, comprised of a progressive habitat shift from pelagic to demersal habitats, is proposed for the spring cohort to explain the observed patterns. Fall-spawned fish of all developmental stages and sizes were virtually absent from estuarine collections. Fall-spawned larval (∼2–10 mm SL) densities peaked in October in inlet and ocean habitats and fish began settling there during the same month at sizes similar to the spring cohort (∼7–8 mm SL). This research confirms that there are important cohort-specific and life-stage dependent differences in young-of-the-year (YOY) windowpane habitat use in southern New Jersey and perhaps in other east coast US estuaries. These differences may affect the overall contribution that each cohort makes to a given year class and thus, may have an important role in determining the recruitment dynamics of this species.

Temporal and spatial variation in settlement of the gastropod Concholepas concholepas in natural and artificial substrata

Settlement of Concholepas concholepas (Gastropoda: Muricidae) on natural and artificial substrata was studied between April 1999 and March 2001 at two sites in central Chile; the Las Cruces Marine Reserve and El Quisco Management and Exploited Area. Four different artificial materials were tested in the low intertidal zone during 1999 settlement season to determine their properties as settlement and microhabitat substrata for competent Concholepas larvae. Globular pads made of plastic filaments were identified as the best artificial collectors, exhibiting overall higher settlement rates than rock plots and lower variability among replicates within a given site. Thus, subsequent monitoring of settlement used only these globular pads that were replaced twice monthly. The temporal pattern of settlement was remarkably similar from year to year, starting at the end of austral winter (August–September) and ending in summer (December–January), defining a temporally restricted settlement season. Settlement at two sites within the Marine Reserve of Las Cruces was significantly higher than at sites in El Quisco. However, during the second settlement season, an additional site at El Quisco exhibited settlement rates comparable to those observed at Las Cruces. The results show that Concholepas settlement varies significantly over scales of several hundreds of metres as well as tens of kilometres, probably due to differences in coastal oceanographic conditions.

Distribution changes after settlement in 6 species of damselfish (Pomacentridae) in One Tree Island lagoon, Great Barrier Reef

While larval supply patterns playa major role in determining the distribution and abun- dance of reef fishes at a range of spatial and temporal scales, events occurring in the weeks after set- tlement may also significantly alter the demography of a juvenile population. I monitored over 2 sum- mers the arrival of new recruits of 6 species of benthic dams elfish onto continuous and patch reef habitat in One Tree Island lagoon. Each species had specific habitat preferences, and most showed some form of patchiness in spatial and temporal distribution at settlement; however, this was most likely a result of group settlement rather than habitat patchiness. Tagged recruits of Pomacentrus amboinensis remained within 1 m of their settlement site for at least the first 36 d on continuous reef, while known individuals of other species also moved little during this period, suggesting that disap- pearances were likely to be due to mortality. Mortality of recruits varied among species, years and habitats (patch vs continuous reef), and consequently spatial distributions of fish changed after set- tlement at the scale of lOs of metres (within-site) and several kilometres (among 8 sites). The spatial patchiness in distributions was not consistent among species, sites or years, suggesting that spatial variation in substrate did not have a major effect on settlement variation at this scale. These results show that the settlement signal may be obscured in the first few weeks post-settlement, and that less- frequent censuses, commonly used as proxies for high-frequency monitoring of settlement, may not accurately hind cast spatial or temporal patterns of settlement.

Temporal patterns of settlement in the temperate reef fish Paralabrax clathratus

Variation in settlement of kelp bass, Paralabrax clathratus, from the pelagic to benthic environment was monitored daily during the summer 1998 on the leeward side of Santa Catalina Island, California. Settlement collectors were placed underwater on buoy lines at 5 to 7 m depth to provide a standardized form of spatial and structural refuge for settling larvae. SCUBA divers retrieved and replaced collectors each day for 58 d and totaled the number of kelp bass settlers found. Settlement of kelp bass occurred nonrandomly around the lunar cycle, suggesting a semi-lunar pat- tern of settlement just after the new and full moons, with peak settlement occurring approximately 5d after the full moon. A high, positive correlation was found between settlement and tidal ampli- tude, and between settlement and onshore winds. A high negative correlation was found between settlement and sea surface temperature. This indicates a strong relationship between settlement of kelp bass and high amplitude tides, drops in sea surface temperature and strong onshore winds. These results suggest that internal tidal bores were a likely means of onshore transport, because bores produce near-bottom onshore flow and are prevalent during high amplitude or spring tides, but especially, they coincide with abrupt drops in sea surface temperature. Back-calculated spawn dates of successful settlers suggested a semi-lunar pattern of spawning just after the new and full moons, with peak activity occurring near the full moon. Kelp bass that settled at spring tides were signifi- cantly younger and smaller than kelp bass that settled at neap tides, thus suggesting that settlement of kelp bass is enhanced and larval durations shortened by oceanographic features such as internal tidal bores. Therefore, behavioral or passive synchronization to the lunar and/or tidal amplitude cycles by adult kelp bass during spawning and by kelp bass larvae during settlement result in predictable peaks in daily settlement.

Modelling settlement in open populations of reef fishes

Processes that act on individual larvae or on whole larval cohorts can affect settlement patterns in open marine populations. The interaction of these processes is explored using an individual-based simulation model in which the temporal pattern of settlement is the culmination of spawning, larval mortality, and larval duration. The model yielded a wide range of settlement patterns derived from a single spawning pattern. Sensitivity analyses indicate temporal settlement distributions are robust to the mortality rate but are sensitive to the variance associated with larval duration. We applied real data on coral reef fishes (larval production and settlement) to our model to generate hypotheses concerning the influence of cohort-wide and individual processes on their larval lives. Settlement of four out of six species was well matched by our model. Results of species matched by our model showed an approximately equal balance of cohort-wide and individual processes on larval mortality. Results for two species suggest individual-based factors predominantly influence larval duration, while results for another suggest cohort-wide processes predominate. That the settlement of two species was not adequately described using this model suggests additional factors, such as larval behaviour, should be considered by future modelling efforts.

Spatial and temporal patterns of settlement of the brown macroalgae Turbinaria ornata and Sargassum mangarevense in a coral reef on Tahiti

Turbinaria ornata and Sargassum mangarevense are the most conspicuous macroalgal species that grow on the reefs of Tahiti and other high islands of French Polynesia. This study reports on a quantitative investigation of spatial and seasonal settlement efficiencies and dispersal distances for these 2 species in a coral reef habitat on Tahiti. Settlement patterns of germlings were observed in situ on settlement plates placed around parental thalli during 2 seasons (hot and cold). For both species, the dispersal of germlings was limited to within 90 cm of the parental thalli, and the greatest number of settled germlings was observed during the cold season. T. ornata showed a higher attachment ability and lower dispersal distances than S. mangarevense. A model of dispersal is suggested for the 2 species showing a decrease in germling number with distance from parental thalli. Dispersal of germlings appears to be influenced by the dominant current during their release. This short-distance dispersal allows rapid establishment and maintenance of local populations, and is consistent with the explanation of the metapopulation distribution of the 2 species. The 2 species did not release all oogonia present in their reproductive structures. T. ornata had a stock of oogonia that varied seasonally (with low amounts during the hot season), whereas there was no seasonal variation in the oogonia stock of S. mangarevense. Recently, isolated atolls have been settled by T ornata but not by S. mangarevense. It is proposed that the tendency for fertile thalli of T. ornata to float over long distances, combined with its oogonia stock and higher settlement efficiencies, could account for its greater capacity to colonize new areas, as compared to S. mangarevense.

Spatial and temporal patterns of settlement among sparid fishes of the genus Diplodus in the northwestern Mediterranean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 168:45-56 (1998) - doi:10.3354/meps168045 Spatial and temporal patterns of settlement among sparid fishes of the genus Diplodus in the northwestern Mediterranean Laurent Vigliola1, Mireille L. Harmelin-Vivien1,*, Franco Biagi2,3, René Galzin4, Antoni Garcia-Rubies5, Jean-Georges Harmelin1, Jean-Yves Jouvenel4, Laurence Le Direach-Boursier1,6, Enrique Macpherson5, Leonardo Tunesi7 1Centre d'Oceanologie de Marseille, CNRS UMR 6540, Université de la Méditerranée, Station Marine D'Endoume, F-13007 Marseille, France 2Universitá di Pisa, Dipartimento di Scienze dell'Uomo e dell'Ambiente-DSUA, Via A. Volta 6, I-56100, Italy 3Centro Interuniversitario di Biologia Marina ed Ecologica Applicata-CIBM, I-52127 Livorno, Italy 4Ecole Pratique des Hautes Etudes, CNRS URA 1453, Université de Perpignan, F-66860 Perpignan Cedex, France 5CSIC, Centro de Estudios Avanzados de Blanes, Camino de Santa Barbara, E-17300 Blanes, Spain 6GIS Posidonie, Parc Scientifique et Technologique de Luminy, Case 901, F-13288 Marseille Cedex 09, France 7ICRAM, Via L. Respighi 5, I-00197 Roma, Italy ABSTRACT: Juvenile settlement of 3 sparid fish species, Diplodus puntazzo, Diplodus sargus and Diplodus vulgaris, was studied over 3 yr at 20 stations located at 5 sites in the NW Mediterranean Sea: 1 site in Spain (Girona), 2 in France (Banyuls and Marseille) and 2 in Italy (Portofino and Elba). When all sites and years were combined, 71% of the settlers recorded belonged to D. vulgaris, 25% to D. sargus and 4% to D. puntazzo. Settlement was seasonal, with D. sargus settling in May-June, D. puntazzo in October-November, and D. vulgaris in 2 pulses, the first in November-December and the second in January-February. Settlement intensity varied spatially, temporally, and among species. At a small spatial scale (within site), settlement intensity varied between stations and particularly between years. At a large spatial scale (among sites), settlement intensity varied among sites, with Marseille and Girona generally experiencing higher settlement than other sites. No difference in settlement intensity was observed between protected and unprotected areas. The settlement of D. sargus was higher in 1994 than in 1993 and 1995 at all sites, suggesting the influence of meso-scale hydroclimatic conditions on the settlement success of this species. The settlement of D. vulgaris was higher in 1993 in the western part of the NW Mediterranean, and in 1994 in the eastern part. No consistent spatial trend over time was seen for D. puntazzo. Thus, settlement intensity of Diplodus species to nearshore habitats in the NW Mediterranean exhibited high year-to-year variations at both local and regional scales. KEY WORDS: Settlement · Sparid fish · NW Mediterranean · Spatial variability · Temporal fluctuations Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 168. Publication date: July 09, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

Forty-eight years of landscape change on two contiguous Ohio landscapes

This study analyzes the current and historic structure of two contiguous, rural landscapes covering approximately 242 km2 in central Ohio, USA: a till plain landscape with relatively homogeneous topography and soils, and a moraine landscape with greater geomorphological diversity and heterogeneity. These landscapes were chosen because they were both heavily dominated by agriculture during 1900–1940 and were both initially surveyed by the metes-and-bounds system. They differed, however, in the temporal pattern of settlement and development and in the inherent agricultural capability of their soils. We combined analysis of aerial photographs from 1940, 1957, 1971, and 1988 with historical archives and other available mapped data in a GIS data base to facilitate analysis of both spatial and temporal patterns of change. On the moraine, the agricultural matrix decreased over time as forest, urban/suburban areas, and industry increased. In contrast, on the till plain agricultural landcover increased through 1988, with concommitant decreases in upland forest and oak savanna. The moraine landscape exhibited greater diversity and equitability than the till plain on each date. The till plain had its greatest diversity and equitability in 1940, whereas the moraine increased in diversity and equitability during each time period. The undulating topography of the moraine encouraged landcover dynamism rather than stability, whereas the more homogeneous till plain exhibited considerable inertia. Patch and matrix shape remained constant and predominantly angular over the 48 year study period. Differences in the physical environment, especially topography and soil capability, and the socioeconomic environment, especially agricultural policies and patterns of urbanization, resulted in these two contiguous landscapes having different trajectories of change. It is clear from this study that socioeconomic factors must be combined with the physical setting to fully understand patterns of change in human-dominated landscapes.

Temporal variability in settlement of a coastal fish (Sillaginodes punctata) determined by low‐frequency hydrodynamics

The temporal pattern of settlement of King George whiting (Sillaginodes punctata) in Port Phillip Bay, Australia, was compared with the temporal ingress of passive particles to the bay from adjacent coastal waters, predicted by a numerical hydrodynamic and dispersal model. The settlement data and the numerical model showed significantly correlated pulsing on an approximate 10–14‐d period. Pulsing was not obviously associated with individual oceanographic or climatic variables but was most likely caused by a combination of factors related to the passage of pressure systems and associated rotating winds that occur on a 7–14‐d cycle in this region. Such factors may include low‐frequency oscillations related to barometric pressure, reversals in longshore currents, and coastal trapped waves. Additionally, these processes would interact with the spring‐neap tidal cycle. The strong tidal currents in the region of settlement may overwhelm the behavioral responses of larvae and cause them to act as passive particles. High interannual variability in recruitment of S. punctata may relate to variation in the frequency and timing of hydrodynamic events that allow transport of larvae to juvenile habitats.