Temperate Coast Research Articles

Nutrient enrichment intensifies hurricane impact in scrub mangrove ecosystems in the Indian River Lagoon, Florida, USA.

Mangroves are an ecological assemblage of trees and shrubs adapted to grow in intertidal environments along tropical, subtropical, and warm temperate coasts. Despite repeated demonstrations of their ecologic and economic value, multiple stressors including nutrient over-enrichment threaten these and other coastal wetlands globally. These ecosystems will be further stressed if tropical storm intensity and frequency increase in response to global climate changes. These stressors will likely interact, but the outcome of that interaction is uncertain. Here, we examined potential interaction between nutrient over-enrichment and the September 2004 hurricanes. Hurricanes Frances and Jeanne made landfall along Florida's Indian River Lagoon and caused extensive damage to a long-term fertilization experiment in a mangrove forest, which previously revealed that productivity was nitrogen (N) limited across the forest and, in particular, that N enrichment dramatically increased growth rates and aboveground biomass of stunted Avicennia germinans trees in the interior scrub zone. During the hurricanes, these trees experienced significant defoliation with three to four times greater reduction in leaf area index (LAI) than control trees. Over the long-term, the +N scrub trees took four years to recover compared to two years for controls. In the adjacent fringe and transition zones, LAI was reduced by > 70%, but with no differences based on zone or fertilization treatment. Despite continued delayed mortality for at least five years after the storms, LAI in the fringe and transition returned to pre-hurricane conditions in two years. Thus, nutrient over-enrichment of the coastal zone will increase the productivity of scrub mangroves, which dominate much of the mangrove landscape in Florida and the Caribbean; however, that benefit is offset by a decrease in their resistance and resilience to hurricane damage that has the potential to destabilize the system.

Spatial autocorrelation potentially indicates the degree of changes in the predictive power of environmental factors for plant diversity

In the literature of ecological indicators, more attention has yet to be paid to the potential effects of spatial autocorrelation (SAC) on the prediction of plant community structure. At a selected foredune ridge in a temperate coast of South Korea, this research developed two regression models: (1) a non-spatial ordinary least squares (OLS) in which the fine-scale (ca. 10m) variability of diversity was predicted by soil and topographic parameters and (2) a spatial model in which spatial filters extracted by spatial eigenvector mapping were incorporated as additional predictors into the original OLS. After such incorporation, a reduction apparently occurred in the predictive power of the environmental variables, especially those with an inherently high amount of SAC. For example, Mg2+ was the most significant predictor for species diversity in OLS, but it became insignificant in spatial regression. This indicates that, during the incorporation of SAC, the predictive importance of Mg2+ was replaced by that of spatial filters. In other words, because the SAC of Mg2+ was inherently strong (global Moran's I=0.68, p<0.001), this soil attribute became redundant when the spatial filters were added to the non-spatial OLS. These discussions corroborate the general idea of this paper that SAC potentially indicates the degree of shifts in the predictive power of environmental factors for plant diversity. In sum, we suggest that environmental variables, which are highly structured over space, should be the target of special attention and care in future modeling attempts aiming to predict the spatial patterns of plant species diversity in coastal dunes. This fine-scale approach can also be applied to macroecological studies along a variety of ecological systems, spanning latitudinal or disturbance gradients.

REVIEW: Potential effects of kelp species on local fisheries

Summary Kelp species are ecosystem engineers in temperate coasts, where they provide valuable services to humans. Evidence of the declines of kelp forests exists from several regions, but their effects on fisheries still need to be elucidated. More effective management strategies for sustainable fisheries require a synthesis of research findings and an assessment of how research could be improved to fill current gaps. This review aimed to: (i) summarize the available evidence on the influence of changes in kelp density and/or area on the abundance and diversity of associated fisheries and (ii) examine how research on kelp–fisheries interactions could better support effective management. Most studies (67%) reported data ascribable, directly or indirectly, to a positive relationship between kelp and fishery‐relevant variables, 11% provided evidence of a negative relationship, 15% indicated species‐specific findings and the remaining found unclear or ‘neutral’ relationships. Important shortcomings were identified, including the paucity of experimental studies suitable to test for unequivocal cause–effect relationships, the disproportion between North America, which is well‐studied, and other regions and between the large number of fish‐based investigations and the small number of those focusing on other commercially important organisms, and the general lack of studies carried out over spatial and temporal scales comparable to those of global processes driving patterns of distribution of both kelps and fisheries. Synthesis and applications. The consistency of most studies in showing a positive kelp–fishery relationship supports the protection of kelp habitats stated by current environmental directives. However, achieving their goals requires that the limitations we detect are addressed through better connections between research, management practice and policy. This would require the following: (i) researchers to combine multiple approaches (large‐scale experimental studies and modelling) for the analysis of kelp–fisheries relationships; (ii) funding agencies to provide resources needed to fill the existing gaps; and (iii) researchers and institutions from less studied regions to strengthen collaborations with those from regions where there have been more investigations into kelp–fishery systems. This is essential under present and predicted environmental changes, with the ultimate aim of conserving and allowing the sustainable use of critically important habitats and of fishery resources relying on these.

Study on bioaccumulation and biosorption of mercury by living marine macroalgae: Prospecting for a new remediation biotechnology applied to saline waters

This study aimed to assess and explore the bioaccumulation capabilities of three different macroalgae species, Ulva lactuca (green), Gracilaria gracilis (red) and Fucus vesiculosus (brown), very common on temperate coasts and estuaries, for the removal of mercury (Hg) from contaminated waters (with high salinity), using environmentally realistic concentrations of metal (10–100μgL−1). Levels of Hg accumulated by all seaweeds ranged between 20.8 and 208μgg−1, corresponding to bioconcentration factors of c.a. 2000. A comparative evaluation of bioaccumulation (living biomass) and biosorption (dried biomass) was performed for U. lactuca, which had displayed the best performance in accumulating Hg. The removal conducted by the living seaweed (mmacroalgae/Vsolution≈500mgL−1), although slower, was more promising since all Hg levels were reduced by about 99%, fulfilling the European criteria for drinking water quality. Pseudo-second-order and Elovich models described quite well the experimental data, assuming a process essentially of chemical nature. Determination of total Hg content in algal biomass over time, allowed to confirm and to follow the uptake of this metal by the living organism. Volatilization of Hg or its conversion to organo-metallic forms (0.02–0.05%) was negligible during the decontamination process.Overall, the results are a contribution for the development of an efficient and cost-effective water remediation biotechnology, based on the use of living macroalgae to promote the removal of Hg.

Biogeographic Affinities of Dictyotales from Madagascar: A Phylogenetic Approach

During the Atimo Vatae research cruise of 2010, the seaweed flora of the southern coast of Madagascar was extensively sampled. Here we report on the species diversity and biogeographic affinities of the brown algal order Dictyotales, which was assessed using DNA-barcoding makers. Molecular identification resulted in 23 MOTU's belonging to 9 genera. From a biogeographic perspective Madagascar is considered to be part of the large tropical Western Indo-Pacific realm. However, only 3 out of 23 species confirmed this affinity. In contrast, species- and genus-level links to the more temperate coast of KwaZulu-Natal were as prominent (4 species) and 6 species represent endemic species. The remaining species were either widely distributed in tropical regions or their affinities were unclear. In conclusion, the Dictyotales data do not suggest the flora of southern Madagascar is unequivocally a part of the tropical Western Indo-Pacific realm, but rather a region of overlap, where more temperate species thrive in conjunction with some Indo West Pacific (IWP) elements.

QUANTIFYING CLIMATE CHANGE AND DETERMINING FUTURE COASTAL DESIGN STORMS FOR EASTERN AUSTRALIA

Coastal inundation has both potential marine and inland contributions. Using a suite of Global Circulation Models, their skill in representing the key fundamental coastal engineering design forcings (mean sea level pressure, wind and precipitation) has been quantified at the 20 year ARI. Skill is assessed by comparison with measured and assembled data along the temperate east Australian coast. Clear extreme distributions are available from GCM output which show no sign of saturation within the tails of extreme distributions. Extreme surface pressures and winds are comparable with the available data giving confidence to the coastal engineering community that GCMs provide data that is suitable for coastal engineering design. GCMs also provide much longer and more detailed data than is available from equivalent measured records. When changes under the A2 scenario are considered, the consensus of the models is that little change in 20 year extreme surface pressures and rainfall are anticipated over the next 100 years with an accompanying 10% decrease in design wind.

Scorched mussels (BIVALVIA: MYTILIDAE: BRACHIDONTINAE) from the temperate coasts of South America: Phylogenetic relationships, trans-Pacific connections and the footprints of Quaternary glaciations

This study addresses aspects of the phylogeny and phylogeography of scorched mussels (BIVALVIA: MYTILIDAE: BRACHIDONTINAE) from southern South America (Argentina and Chile), as well as their ecophylogenetic implications. Relationships were inferred from sequences of two nuclear (28S and 18S) and one mitochondrial (COI) genes, using Bayesian and maximum likelihood analyses. Our results indicate that the monophyletic BRACHIDONTINAE include three well supported clades: [i] Brachidontes Swainson (=Hormomya Mörch), [ii] Ischadium Jukes-Browne+Geukensia van de Poel, and [iii] Austromytilus Laseron+Mytilisepta Habe (usually considered a member of the SEPTIFERINAE)+Perumytilus Olsson. Species of clade [iii] are distributed along the temperate coasts of the Pacific Ocean. Available evidence supports divergence between Austromytilus (Australia) and Perumytilus (South American) following the breakup of Australian, Antarctic and South American shelves. Four brachidontins occur in southern South America: Brachidontes rodriguezii (d’Orbigny), B. granulatus (Hanley), and two genetically distinct clades of Perumytilus. The latter are confined to the Chile-Peru (North Clade) and Magellanic (South Clade) Biogeographic Provinces, respectively warm- and cold-temperate. The South Clade is the only brachidontin restricted to cold-temperate waters. Biogeographic considerations and the fossil record prompted the hypothesis that the South Clade originated from the North Clade by incipient peripatric differentiation, followed by isolation during the Quaternary glaciations, genetic differentiation in the non-glaciated coasts of eastern Patagonia, back-expansion over southern Chile following post-LGM de-glaciation, and development of a secondary contact zone between the two clades in south-central Chile. Evidence of upper Pleistocene expansion of the South Clade parallels similar results on other organisms that have colonized coastal ecosystems from eastern Patagonia since the LGM, apparently occupying free ecological space. We emphasize that the assembly of communities cannot be explained solely in terms of environmental drivers, as history also matters.

Environmental tolerance of the two invasive species Ciona intestinalis and Codium fragile: their invasion potential along a temperate coast

Ciona intestinalis and Codium fragile are among the most successful invasive species in marine systems worldwide, and they are currently in the process of expanding their distributional ranges along the Chilean coast. Herein we evaluated whether their tolerance to a wide range of environmental conditions contributes to the invasion potential of these two species. To examine the environmental tolerance and performance (e.g., growth) of these non-indigenous species, unifactorial experiments (8–10 days) were conducted with different environmental factors (solar radiation, salinity and temperature). Based on the results, the potential risk of invasion along the Chilean coast was evaluated for both species using a mechanistic niche modeling approach. Both species can tolerate extensive ranges of the abiotic factors salinity and temperature, with C. intestinalis being more tolerant to cold-temperate waters. Also, C. intestinalis was more susceptible to high light intensities than C. fragile. These results confirm those of other experiments, and the outcome of the niche modeling shows that both species can potentially invade most regions of the Chilean coast with the exception of the Magellan region. The results suggest that physiological capacity to tolerate and perform in a wide range of physical conditions is a pre-requisite for successful invasions by littoral biota, but predation and possibly competitive exclusion can slow down the invasion success of C. intestinalis, which in contrast to C. fragile, is consumed by many benthic predators. Sexual and asexual reproduction as well as buoyancy of its thalli further contribute to the dispersal and colonization success of C. fragile. Based on these considerations, it is concluded that the invasion risk of C. fragile along the Chilean coast is substantially higher than that of C. intestinalis.

Herbivory mediates the expansion of an algal habitat under nutrient and CO2 enrichment

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 497:87-92 (2014) - DOI: https://doi.org/10.3354/meps10557 Herbivory mediates the expansion of an algal habitat under nutrient and CO2 enrichment Laura J. Falkenberg*, Sean D. Connell, Bayden D. Russell Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, South Australia 5005, Australia *Corresponding author: laura.falkenberg@adelaide.edu.au ABSTRACT: Certain environmental conditions facilitate the control of primary producers by herbivores. Environmental change can, therefore, mediate the strength of consumption relative to production such that the abundance of primary producers is altered, potentially driving phase-shifts from one habitat type to another (e.g. the displacement kelp forests by mats of turfs along temperate coasts). Here, we assessed the extent to which herbivores may counter the increased cover of kelp-competitors (i.e. turfs) anticipated to be caused by enriched nutrients and CO2. Specifically, we experimentally enriched nutrients and CO2 and quantified the change in cover of algal turfs in the presence and absence of gastropod grazers. In the absence of grazers, turf algae responded positively to the combination of enriched nutrients and CO2 such that they occupied >95% of available space. In contrast, where grazers were present, sparse covers of algal turfs were maintained even under CO2 and nutrient enrichment (i.e. turfs occupied <5% of available space). This result indicates that consumption by grazers increased where enrichment of nutrients and CO2 facilitated greater algal cover such that cover continued to be largely restricted. By recognising the environmental conditions which will maintain or disrupt the balance between the processes of production and consumption, we may improve forecasts regarding the probability of habitat stasis or shifts. KEY WORDS: Carbon dioxide · Climate change · Grazers · Nutrients · Ocean acidification · Eutrophication · Turf-forming algae Full text in pdf format PreviousNextCite this article as: Falkenberg LJ, Connell SD, Russell BD (2014) Herbivory mediates the expansion of an algal habitat under nutrient and CO2 enrichment. Mar Ecol Prog Ser 497:87-92. https://doi.org/10.3354/meps10557 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 497. Online publication date: February 05, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

The decomposition of estuarine macrophytes under different temperature regimes

The Great Brak Estuary is a temporarily open/closed system situated along the warm temperate coast of the Western Cape, South Africa. The estuary is subject to a variety of anthropogenic impacts (e.g. freshwater abstraction and sewage discharge) that increases its susceptibility to prolonged periods of mouth closure, eutrophication, and ultimately the formation of macroalgal blooms. The aim of this study was to determine the decomposition characteristics of the most dominant submerged macrophyte and macroalgal species in the Great Brak Estuary. Laboratory experiments were conducted to determine the effect of different temperature regimes on the rate of decomposition of 3 macrophyte species and the extent of inorganic nutrients released. The results demonstrated that anaerobic decomposition of Zostera capensis, Ruppia cirrhosa, and Cladophora glomerata resulted in high levels of inorganic nutrient release over the 28-day study period. Ammonium (NH4+) was the dominant form of dissolved inorganic nitrogen (DIN) released during the decomposition process for all three species. The low levels of total oxidised nitrogen (nitrate and nitrite) released during decomposition were attributed to the inhibition of nitrification by heterotrophic bacteria under anoxic conditions. The relative levels of dissolved inorganic phosphorus (DIP) released were lower than that observed for DIN, and peaked early on in the experimental period (ca. 7 days), thereafter stabilising or decreasing. The DIP levels were explained, in part, by the varying nutrient requirements and limitations of each species (e.g. nitrogen-limited). The release of inorganic nutrients was greatest at higher temperatures (i.e. 25°C and 30°C), due to the reduced bacterial activity experienced at lower temperatures (i.e. 15°C). Ultimately, estuarine health deteriorates during macroalgal blooms, and therefore it is important to implement mitigation measures, such as artificial mouth breaching and plant harvesting, in order to minimise or reverse the effects of eutrophication.Keywords: Great Brak Estuary, decomposition, temperature, inorganic nutrient release, Cladophora glomerata, Zostera capensis, Ruppia cirrhosa

What are algal turfs? Towards a better description of turfs

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 495:299-307 (2014) - DOI: https://doi.org/10.3354/meps10513 AS WE SEE IT What are algal turfs? Towards a better description of turfs S. D. Connell1, M. S. Foster2, L. Airoldi3,4 1Southern Seas Ecology Laboratories DX 650 418, School of Earth and Environmental Sciences, University of Adelaide, South Australia 5005, Australia 2Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA 3Dipartimento di Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via S. Alberto, 163, 48123 Ravenna, Italy 4Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA *Corresponding author: sean.connell@adelaide.edu.au ABSTRACT: The use of standardised classifications, or operational definitions, is essential if different researchers are to measure and compare similar entities. In the marine realm, algal ‘turfs’ are increasingly reported to be globally expanding at the expense of kelps and canopy-forming algae. However, ecological research about the underlying drivers of this shift is limited by a vague and inconsistent definition of what exactly a turf is. In order to stimulate more effective descriptions of ‘turfs’ and facilitate communication of research outcomes and comparisons across studies, we reviewed the use of the term turf in ecological studies of temperate coasts and coral reefs and (1) identified the main types and distribution of algal assemblages known as ‘turfs’, (2) examined the descriptions of turfs so that we may recognise some general characteristics, including those contingent on environmental conditions; and (3) offered character descriptions that could improve communication and comparisons. These descriptors centre on reporting information on the morphology, height, density of thalli, the amount of sediment trapped in turfs and a description of the area covered by turfs, including their patchiness and persistence. Our review recognised these as common attributes that could be usefully described across a wide range of circumstances and provide insights into the ecology of turfs and their interactions with other assemblages in a community. The use of common descriptors would provide the term ‘turf’ with greater scientific value. KEY WORDS: Algae · Coral · Definition · Epilithic · Rock · Temperate · Turf-forming Full text in pdf format Supplementary material PreviousCite this article as: Connell SD, Foster MS, Airoldi L (2014) What are algal turfs? Towards a better description of turfs. Mar Ecol Prog Ser 495:299-307. https://doi.org/10.3354/meps10513 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 495. Online publication date: January 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Occurrence of larval fishes in a rocky shore-associated nursery area in temperate South Africa, with emphasis on temperature-related growth in dominant Sparidae

Larval fishes were studied in Shark Bay on the warm, temperate south-east coast of South Africa. The bay is a small, shallow, subtidal area associated with a rocky shore. Sampling took place fortnightly for a period of one year (September 2004–August 2005) to assess composition, abundance and growth of fishes. The objectives of the study were to assess the extent of use of this habitat type by larvae throughout the year and to ascertain what temperature advantages this relatively warm habitat could have on growth of dominant species. A total of 10 fish families, represented by 16 taxa, was collected using a specially modified beach seine net (mesh aperture 500 µm). Shark Bay was utilised extensively by Diplodus capensis and Sarpa salpa and to a lesser extent by Clinus supercilious, Liza spp. and Mugil cephalus. Mean catch per unit effort (CPUE) of larvae was high (>500 larvae per net haul), peaking at ∼7 500 larvae in a single haul that consisted mostly of postflexion-stage Sparidae. There was a weak, negative correlation (−0.24) between temperature and overall CPUE, which reflected either the seasonality or protracted nature of spawning by the species occurring in the bay. There was no significant difference in CPUE between the moon phases sampled on the spring tides in this study. Shark Bay was dominated by postflexion-stage larvae, consisting in particular of species common to tide pools during the juvenile stage. Certain species were sampled for only short periods during the year. The year-round occurrence and high abundance of the two dominant species indicate that Shark Bay represents an important nursery habitat for the completion of the larval phase. These species exhibited exponential growth that lagged behind small increases in temperature, highlighting the importance of access to shallow, warm habitat that allows larval growth to increase, leading to earlier settlement into juvenile habitat and thereby reducing the pelagic larval duration.

Neosiphonia ramirezii sp. nov. (Rhodomelaceae, Rhodophyta) from Peru

The genus Neosiphonia Kim and Lee 1999 contains approximately 30 species worldwide. Unidentified samples from Peru are here described as a new species, Neosiphonia ramirezii sp. nov., on the basis of morphological and molecular data. N. ramirezii sp. nov. is characterized by the presence of a limited prostrate system, well-developed erect filaments, rhizoids cut off from pericentral cells by cross walls, four pericentral cells that are completely ecorticate, scarce trichoblasts, inconspicuous scar cells, procarps with three-celled carpogonial branches, spermatangial branches developed from basal cells of forked trichoblasts, and spirally arranged tetrasporangia. Our new species is distinct from N. flaccidissima (Hollenberg) Kim et Lee, N. sphaerocarpa (Borgesen) Kim et Lee, and N. savatieri (Hariot) Kim et Lee from the Pacific temperate coast of South America and from 14 Neosiphonia species reported worldwide by having limited prostrate filaments attached by numerous rhizoids, dichotomous (“Y” shaped) branches in the main axes, and scarce trichoblasts. Phylogenetic rbcL analyses confirm the placement of the new taxon as a distinct species in the genus Neosiphonia.

Habitat choice and recruitment of tropical fishes on temperate coasts of Japan

Tropical reef corals are expanding on Japanese temperate coasts in response to rising sea surface temperatures, and many tropical fish juveniles have been observed routinely in these coral habitats. The present study explored how offshore tropical fish larvae locate coral habitat on the temperate coasts of Japan. Settlement-stage larvae were sampled between July and October 2009–2011 with light traps anchored on coral-replete and coral-free habitats (rocky habitats) at two-level distance (distance between each habitat type was 6 km and 500 m, respectively). Larval abundance was significantly higher on the coral-dominated habitat than that on the rocky habitat at both short and long distance sites, suggesting that coral habitats attract offshore tropical fish larvae. In underwater visual survey, Chaetodontidae and Pomacentridae juveniles were more abundant in coral habitats than in rocky habitats at both the sites, and a laboratory habitat choice experiment demonstrated that these larvae showed a preference for corals rather than rocks. In contrast, densities of juvenile Mullidae did not differ between the coral and rocky habitats, and the larvae did not show a substrate preference in the habitat choice experiment. These observations suggest that habitat choice at settlement possibly accounts for the differences in settlement patterns of tropical fishes between the two habitats. Taken together, our results showed that most tropical fish larvae colonize their settlement coast at a scale of ~0.5 km, and that they may locate coral habitats after reaching a reef. Moreover, the results suggest that coral habitat expansion on temperate coasts will lead to an increase in coral-associated tropical fishes and will change assemblage structures of fishes on temperate coasts.

Fish response to expanding tropical Sargassum beds on the temperate coasts of Japan

Fish response to expanding tropical Sargassum beds on the temperate coasts of Japan

Rapid isolation of 14 microsatellite markers for Van Diemen’s siphon limpet Siphonaria diemenensis

Siphon limpets are an ecologically important component of the intertidal zone of Australia's temperate coast. Using 1/16 of a shotgun pyrosequencing plate, a set of 14 microsatellites was developed for the Van Diemen's siphon limpet (Siphonaria diemenensis). From 2,744 sequences that contained putative microsatellite motifs, 18 were selected for primer design and tested for amplifica- tion. Fourteen microsatellite loci were successfully geno- typed in 48 specimens of S. diemenensis from two localities. The number of alleles per locus varied from 5 to 35 (mean = 14.6) and the observed heterozygosity ranged from 0.53 to 0.90 (mean = 0.77). Only one locus showed significant deviation from Hardy-Weinberg equilibrium, probably due to null alleles. No linkage disequilibrium between pairs of loci was detected. Connectivity and sea- scape genetic studies on siphon limpets using the markers reported here should provide important information for management of temperate Australian marine biodiversity.

Relationship between pelagic larval duration and abundance of tropical fishes on temperate coasts of Japan

The influence of pelagic larval duration (PLD) and egg type dispersal capabilities of 35 demersal and pelagic-spawning tropical fish species is examined in relation to their abundance on the temperate coasts of Japan. The PLDs of pelagic spawners were significantly longer than those of demersal spawners, and a high occurrence of pelagic spawners on the temperate coasts suggests that these fishes are more easily transported to temperate coasts than demersal spawners. For demersal spawners, the common species on the temperate coasts had significantly longer PLDs than the rare species; this suggests that PLD is a major factor influencing the distribution patterns of tropical demersal spawners on temperate coasts. Moreover, a negative correlation between PLD and the abundance of some species of pelagic and demersal spawners suggests the presence of reproductively active fishes in northern subtropical and even in temperate waters.

The use of δ15N signatures of translocated macroalgae to map coastal nutrient plumes: improving species selection and spatial analysis of metropolitan datasets

The definition of the spatial footprint of land-derived nutrient plumes is a key element to the design of initiatives to combat eutrophication in urbanised coastal regions. These plumes, however, are difficult to monitor because of their inherent high-frequency temporal and spatial variability. Biomonitoring with macroalgae provides time-integration of bioavailable nitrogen inputs through the measurement of δ¹⁵N signatures in tissues, and adequate spatial coverage through translocation to desirable monitoring locations. In this study, we used laboratory incubations to compare three different species of macroalgae as bioindicators, and a field experiment to investigate the applicability of the technique for the large-scale mapping of nutrient plumes. Cladophora valonioides was selected for the field experiment as it showed rapid changes in δ¹⁵N values in the laboratory incubations, was abundant in shallow depths making collection cost-efficient, and had tough thalli capable of withstanding deployment in open water. Ecklonia radiata also performed well in the laboratory incubations, but field harvest from subtidal depths was comparatively more expensive. Ulva lactuca had fragile thalli, and large nitrogen reserves that acted to mask the isotopic signal of newly acquired nitrogen. Cladophora valonioides was translocated to 246 sites covering an area of ∼445 km² along the highly urbanized temperate coast of Adelaide, South Australia. The resulting isotopic signatures of nitrogen in tissues were spatially interpolated to produce maps of land-derived nutrient plumes, to model probability and standard error in the predictive surface, and to optimize sampling design.

The Australasian muricid gastropod Lepsiella as Pleistocene visitor to southernmost South America

Six shells belonging to a muricid gastropod species were recovered from a Pleistocene marine raised beach located on Navarino Island, in southern South America. None of the living species in the Beagle Channel or in the area is close, and none of the fossil species in the vicinity regions shows the diagnostic characters of the Navarino Pleistocene fossils. Our material resembles Lepsiella baileyana from southern Australia, although some differences in the suture and in the spire outline are recognized. Haustrinae were previously confined geographically to New Zealand and to the temperate coast of Australia, now extending its range of distribution to southern South America. This finding of Lepsiella ukika sp. nov. is best explained on the basis of transoceanic migration from Australasia by means of the Antarctic Circumpolar Current perhaps during a Quaternary glacial period. The presence of this Pleistocene visitor in southern South America is important because it clearly demonstrates that transcontinental...

Diet of largemouth bass, Micropterus salmoides (Centrarchidae), an invasive alien in the lower reaches of an Eastern Cape river, South Africa

Largemouth bass (Micropterus salmoides) have been introduced to many South African river systems where they become invasive and pose a threat to native biota. The diets of small (32–138 mm TL) and large (192–448 mm TL) sized bass were analysed and compared in a marine fish nursery area in the lower Kowie River on the warm temperate coast of South Africa over a one-year period from March 2009 to February 2010. Dietary differences were detected between the two size groups. Amphipod sp. (% index of relative importance (IRI) = 69.2) and dipterans (Insecta) (%IRI = 21.9) dominated gut contents of small bass while larger bass preyed mostly on odonates (Insecta) (%IRI = 16.3) and the brachyuran Potamonautes sidneyi (%IRI = 80.0). Fish prey was of low importance during this study but comparisons with previous work on the lower Kowie River showed that when the river is flowing, young marine fish recruiting into the freshwater from the estuary become important prey items. These data suggest that in the lower Kowie River bass utilize invertebrate prey at low fish prey abundance and opportunistically feed on migrant fish when these are available.