VARIATIONS IN GROWTH,EROSION, PRODUCTIVITY,AND MORPHOLOGY OF ECKLONIA RADIATA (ALARIACEAE; LAMINARIALES) ALONG A FJORD IN SOUTHERN NEW ZEALAND1

Spatial and temporal patterns of growth, erosion, productivity, and morphology of the dominant habitat‐forming kelp Ecklonia radiata (C. Agardh) J. Agardh were studied bimonthly over 1.5 years in a southern New Zealand fjord characterized by strong gradients in light and wave exposure. Spatial differences in growth were observed with rates at two outer coast, high‐light, wave‐exposed sites reaching 0.42 and 0.45 cm · d^?1, respectively, compared to 0.27 cm · d^?1 at an inner, more homogeneous site. Sporophyte productivity was similar among sites, although population productivity was greater at the outer sites due to population density being 5‐fold greater than at the inner site. It was expected that the inner site would have no pronounced seasonal pattern in growth and productivity due to its homogeneity; however, all three sites displayed maximum rates in late winter/spring and minimal in autumn. Growth rates were 2‐fold greater during the first growth period than the following year. This discrepancy was not correlated to inorganic nitrogen (N) levels, which remained low year‐round (<4 μM), and is likely a result of an interaction between light and temperature, and the photosynthetic capability of E. radiata. Variable pigment content indicated photoacclimation at the inner site. Morphological differences were observed between sites, with E. radiata from the inner site having longer, wider, thinner blades and longer stipes. While E. radiata displayed spatial differences in growth, erosion, productivity, and morphology, populations displayed no temporal differences. These results highlight the need for greater understanding of the mechanisms influencing kelp growth and productivity in a unique marine environment.     

MORPHOLOGICAL VARIATION WITHIN AND BETWEEN NATURAL POPULATIONS OF NON-TIDE POOL FUCUS DISTICHUS (PHAEOPHYTA) IN NEW ENGLAND1,2

The sources of morphological variation in natural populations of Fucus distichus L. ssp. edentatus (De la Pyiaie) Powell and F. distichus L. ssp, evanescens (C. Agardh) Powell from New England were evaluated. Individuals from different populations were morphologically distinct as judged by population means and analysis of variance. A correlation between the plant's form and its habitat was established by field observation. The broadest material grows in calm estuarine habitats, while the narrowest plants occur in exposed, open coastal areas. Major differences in morphology also appear seasonally. In addition, microhabitat factors such as exposure to wave action and elevation explain some morphological variation. Cultured germlings from distinct populations of “evanescens” and “edentatus” type plants were outplanted to an experimental garden in order to ascertain whether the variation was heritable or environmentally induced. The latter experiments indicate that major differences in morphology are genetically determined.     

GENETIC AND MORPHOLOGICAL ANALYSES OF THE SOUTHERN BULL KELP DURVILLAEA ANTARCTICA (PHAEOPHYCEAE: DURVILLAEALES) IN NEW ZEALAND REVEAL CRYPTIC SPECIES1

Many macroalgae exhibit considerable intraspecific morphological variation, but whether such variation reflects phenotypic plasticity or underlying genetic differences is often poorly understood. We quantified both morphological and genetic variation of 96 plants from seven field sites across eastern South Island, New Zealand, to assess genetic differences between morphotypes of the southern bull kelp Durvillaea antarctica (Cham.) Har. Consistent DNA sequence differentiation across mitochondrial, plastid, and nuclear loci was correlated with two broadly sympatric morphotypes: “cape” and “thonged.” These ecologically, morphologically, and genetically distinct bull‐kelp lineages were previously considered to be environmentally determined phenotypes with no underlying genetic basis. Interestingly, the sheltered “cape” lineage appears essentially genetically uniform across its South Island range, whereas the exposed “thonged” lineage exhibits marked phylogeographic structure across its range. Results suggest that D. antarctica in New Zealand comprises two reproductively isolated species.     

The effect of wave exposure on the morphology of Ecklonia radiata

This study examined the consistency of the effect of wave exposure on the morphology of Ecklonia radiata, a small kelp, across a broad geographic range (>1100 km). Fifteen morphological characters were measured on individuals from sites of low (2.5 ± 0.8 S.E.) and high (12.2 ± 2.0 S.E.) wave exposure (Baardseth's index) within six locations in southwestern Australia. With the exception of lateral width (P = 0.0001), none of the morphological characters were consistently statistically different (P > 0.06) between high and low wave exposure and correlations with wave exposure were generally weak (r < 0.60). While 12 of the 15 characters were statistically different (P < 0.008) between sites of different exposure within at least one location, the direction of difference (significant or not) was opposite between some locations for all but one character (lateral width). ANOSIM was not able to separate thalli from high and low exposure when all locations were pooled (Clarke's R = 0.127), but within each location most sites showed better separation (0.126 < Clarke's R < 0.829). Despite the lack of statistical differences, trends suggested that E. radiata responds to exposure by having drag-reducing (small size, narrow laterals and blades, low spinosity) and strength-increasing (relatively large holdfast, thick stipe and thick blades and lamina) morphological traits, as observed for several other kelps in small-scale studies. We conclude that while wave exposure does have an effect on kelp morphology, the effect is not independent of other location-specific processes.     

Regional differences in kelp-associated algal assemblages on temperate limestone reefs in south-western Australia

Abstract. Ecklonia radiata (C. Agardh) J. Agardh kelp beds — a characteristic feature of the nearshore environment along the south‐west Australian coastline — contribute significantly to the coastal biodiversity in temperate Australia, yet, little is known about the organization of these macroalgal assemblages. By compiling existing and new data sets from habitat surveys, we have characterized and compared the structure of kelp‐associated macroalgal assemblages in three regions (Marmion Lagoon, Hamelin Bay and the marine environment neighbouring the Fitzgerald River National Park) across more than 1000 kilometres of the south‐west Australian coastline. 152 macroalgal taxa had been recognized within the three regions and this is in the range of species richness reported from other Australian and African kelp beds. The kelp‐associated algal assemblages were regionally distinct, 66% of all taxa were only found in one region and only 17 taxa were found in all three regions. Adjacent regions shared an additional 13–15 taxa. The regional shifts in assemblage structure were evident in species composition of both canopy and understorey. The organization of assemblages followed a spatial hierarchy where differences in assemblage structure were larger among regions (hundreds of kilometres apart) than among sites within regions (kilometres apart) and differences among sites within region were larger than differences among quadrats within sites (metres apart). Despite this hierarchy each level of nesting contributed approximately the same to total variation in assemblage structure and these spatial patterns were stronger than temporal differences from seasons to 2–3 years. Our results suggest that local and small‐scale processes contribute considerably to heterogeneity in macroalgal assemblages throughout south‐western Australia, and, in particular, our results are consistent with E. radiata exerting a strong influence on macroalgal assemblage structure. Further, our study contradicts the existence of a general south‐west Australian kelp assemblage, although a few species may form the core of E. radiata associations across regions.     

DEFINING TAXON BOUNDARIES IN MEMBERS OF THE MORPHOLOGICALLY AND GENETICALLY PLASTIC GENES CAULERPA (CAULERPALES,CHLOROPHYTA)1

Numerous attempts to capture the morphological variability of the genus Caulerpa have resulted in an unstable classification of numerous varieties and formae. In the present study we attempted to test taxon boundaries by investigating morphological and genetic variation within and between seven taxa of Caulerpa, supposedly belonging to four species, sampled at different sites in a Philippine reef system. Using both field and culture observations, we described the relation between the variability of a set of morphological characters and ecological parameters, such as wave exposure, light intensity, and substrate type. Statistical analyses showed that the limits between two (out of three) ecads of the C. racemosa (Forsskål) J. Agardh complex were obscured by the presence of morphological plasticity. Other studied taxa of Caulerpa (i.e. C. cupressoides [Vahl] C. Agardh, C. serrulata [Forsskål] J. Agardh, and two formae of C. sertularioides [S. Gmelin] Howe) could be grouped based on morphology despite the presence of morphological plasticity. Our results indicated a strong association between light intensity and several quantitative morphological variables. Genetic diversity of these taxa was assessed by partial sequencing chloroplast rbcL and tufA genes and the ycf10‐chlB chloroplast spacer. In all phylogenetic analyses, C. serrulata, C. cupressoides, C. sertularioides, and the three ecads of C. racemosa emerged as distinct genetic units. Despite the presence of morphological plasticity and morphological convergence, a subset of morphological characters traditionally used in taxonomic delimitation still had sufficient discriminative power to recognize the terminal phylogenetic clades.     

PHENOTYPIC PLASTICITY RECONCILES INCONGRUOUS MOLECULAR AND MORPHOLOGICAL TAXONOMIES: THE GIANT KELP,MACROCYSTIS (LAMINARIALES,PHAEOPHYCEAE), IS A MONOSPECIFIC GENUS1

The giant kelp genus Macrocystis C. Agardh (Laminariales, Phaeophyceae) is one of the world’s most ecologically and economically important seaweed taxa, yet its taxonomy remains uncertain. Although the genus currently contains four accepted species based on variable holdfast and blade morphology [M. pyrifera (L.) C. Agardh, M. integrifolia Bory, M. angustifolia Bory, and M. laevis C. H. Hay], numerous recent studies on Macrocystis interfertility, genetic relatedness, and morphological plasticity all suggest that the genus is monospecific. We reviewed this evidence and present an explanation for the extreme phenotypic plasticity that results in morphological variability within Macrocystis, driven by the effects of environmental factors on early development of macroscopic sporophytes. We propose that the genus be collapsed back to a single species, with nomenclatural priority given to M. pyrifera.     

Family‐level variation in early life‐cycle traits of kelp

Temperate kelp forests (Laminarians) are threatened by temperature stress due to ocean warming and photoinhibition due to increased light associated with canopy loss. However, the potential for evolutionary adaptation in kelp to rapid climate change is not well known. This study examined family‐level variation in physiological and photosynthetic traits in the early life‐cycle stages of the ecologically important Australasian kelp Ecklonia radiata and the response of E. radiata families to different temperature and light environments using a family × environment design. There was strong family‐level variation in traits relating to morphology (surface area measures, branch length, branch count) and photosynthetic performance (F_v/F_m) in both haploid (gametophyte) and diploid (sporophyte) stages of the life‐cycle. Additionally, the presence of family × environment interactions showed that offspring from different families respond differently to temperature and light in the branch length of male gametophytes and oogonia surface area of female gametophytes. Negative responses to high temperatures were stronger for females vs. males. Our findings suggest E. radiata may be able to respond adaptively to climate change but studies partitioning the narrow vs. broad sense components of heritable variation are needed to establish the evolutionary potential of E. radiata to adapt under climate change.     

PHYSIOLOGICAL RESPONSES OF ECKLONIA RADIATA (LAMINARIALES) TO A LATITUDINAL GRADIENT IN OCEAN TEMPERATURE1

We tested the ability of sporophytes of a small kelp, Ecklonia radiata (C. Agardh) J. Agardh, to adjust their photosynthesis, respiration, and cellular processes to increasingly warm ocean climates along a latitudinal gradient in ocean temperature (～4°C). Tissue concentrations of pigment and nutrients decreased with increasing ocean temperature. Concurrently, a number of gradual changes in the metabolic balance of E. radiata took place along the latitudinal gradient. Warm‐acclimatized kelps had 50% lower photosynthetic rates and 90% lower respiration rates at the optimum temperature than did cool‐acclimatized kelps. A reduction in temperature sensitivity was also observed as a reduction in Q₁₀‐values from cool‐ to warm‐acclimatized kelps for gross photosynthesis (Q₁₀: 3.35 to 1.45) and respiration (Q₁₀: 3.82 to 1.65). Respiration rates were more sensitive to increasing experimental temperatures (10% higher Q₁₀‐values) than photosynthesis and had a higher optimum temperature, irrespective of sampling location. To maintain a positive carbon balance, E. radiata increased the critical light demand (E_c) exponentially with increasing experimental temperature. The temperature dependency of E_c was, however, weakened with increasing ocean temperature, such that the critical light demand was relaxed in kelp acclimated to higher ocean temperatures. Nevertheless, calculations of critical depth limits suggested that direct effects of future temperature increases are unlikely to be as strong as effects of reduced water clarity, another globally increasing problem in coastal areas.     

An experimental study of geographic variation in avian growth and development

Reciprocal transplant and “common garden” experiments were done to distinguish the genetic and environmental components of geographic variation in growth, development and morphological characters of Mallard Ducks (Anas platyrhynchos) from California, USA and Manitoba, Canada. Most of the variation in growth and development could be attributed to differences in nesting phenology and local environmental conditions. Differences in morphological characters typical of birds in the two wild populations could be induced by transplanting young between localities. All differences between populations disappeared in the F1 offspring from captive breeding crosses, reared in a common environment. These results suggest that population-level variation in growth, development and morphology of Mallards in the wild is environmentally induced.     

Scorpion higher phylogeny and classification, taxonomic anarchy, and standards for peer review in online publishing

Soleglad and Fet's (2003a) attempt to reconstruct the phylogeny of Recent (including extant) scorpions, the revised classification derived from it, and recent emendations, mostly published in their self‐edited online journal, Euscorpius, are deficient. Separate analyses of three independent matrices (morphology, 16S rDNA, 18S rDNA) were presented. In the morphological matrix, 52 binary and 10 tristate trichobothrial characters were replaced with one character comprising six ordered states representing trichobothrial “types”. The remaining matrix of 105 characters was further reduced to 33 “fundamental” characters (20% of the morphological dataset), the analysis of which appears to be the basis for the revised classification presented. The taxon sample for the morphological analysis included 14 supraspecific terminal taxa representing genera, the monophyly of only 7 (12.5%) of which has been confirmed. A composite terminal, assembled from the fragments of fossils that may not be confamilial let alone monophyletic, was created for the Palaeopisthacanthidae, employed as the primary outgroup for the analysis. Other important outgroup taxa, notably eurypterids, xiphosurans and other arachnids, were omitted entirely. The morphological characters presented contained numerous unjustifiable assumptions of character polarity and phylogenetic relationship. An approach to character coding, deliberately adopted to reduce “homoplasy”, biased the analysis towards a preconceived result. Structurally and topographically similar features in different taxa were explicitly assigned separate (often autapomorphic) states according to presumed phylogenetic relationships among the taxa in which they were observed. Putative “reversals” were coded as separate characters or states. Character transformation was forced by ordering, additive coding or Sankoff optimization through allegedly intermediate states for which there is no empirical evidence. Many characters were defined in a manner that demonstrates either a lack of understanding of, or disregard for, established methods and standards of morphological character coding. Some states display overlapping variation whereas others subsume variation that is not structurally or topographically similar. Polymorphic “states” were created for terminals with interspecific variation and unknown “states” for terminals that should have been scored unknown. Many characters were not evaluated for particular terminal taxa, but merely scored inapplicable although the structures and, consequently, the characters in question are present and therefore applicable to them. In view of the significant theoretical and empirical problems with the approach to cladistics taken by Soleglad and Fet, we find no justification for accepting either the results of their analyses or the revised classification derived from them. Pending the outcome of a rigorous phylogenetic analysis, published according to acceptable standards of scholarship in a peer‐reviewed journal, we revert to the suprageneric classification of Scorpiones reflected by the most recent peer‐reviewed, published treatments and reject all changes to the classification proposed by Soleglad, Fet and colleagues since 2001. We argue that an analysis and revised classification of the kind presented in various papers by these authors could not survive the peer‐review process of a mainstream scientific journal. The poor scholarship exemplified by these and other papers published in Euscorpius emphasize the importance of quality control associated with the emergent infrastructure of online publishing. A centralized register of taxa may be the only solution for ensuring quality control in the taxonomy of the future. © The Willi Hennig Society 2005.     

Environmental correlates of phenotypic variation: do variable tidal regimes influence morphology in intertidal seaweeds?

Seaweed morphology is often shaped by the hydrodynamic environment. However, exposure to air at low tide represents an additional factor potentially affecting the morphology of intertidal species. Here, we examined the relationships between the morphology of Hormosira banksii, an important intertidal habitat‐forming seaweed in southern Australia, and environmental factors across multiple spatial scales around the island of Tasmania, Australia. Tasmania is surrounded by a diverse coastline with differences in wave exposure, tidal parameters, and temperature. We sampled Hormosira from four regions (100s km apart), three sites (10s km apart) within each region, and two zones (meters apart; eulittoral and sublittoral) at each site, and measured multiple morphological variables to test for differences in morphology at those different spatial scales. Thirteen environmental variables reflecting wave exposure, tidal conditions, and temperature for each site were generated to assess the relationship between Hormosira morphology and environmental variation. Morphology varied at all spatial scales examined. Most notably, north coast individuals had a distinct morphology, generally having smaller vesicles and shorter fronds, compared to other regions. Tidal conditions were the main environmental factors separating north coast sites from other sites and tidal regime was identified as the best predictor of morphological differences between regions. In contrast to other studies, we found little evidence that wave exposure was associated with morphological variation. Overall, our study emphasizes the role of tidal conditions, associated with emersion stress during low tide, in affecting the morphology of intertidal seaweeds.     

EFFECTS OF THE ENCRUSTING BRYOZOAN,MEMBRANIPORA MEMBRANACEA,ON THE LOSS OF BLADES AND FRONDS BY THE GIANT KELP,MACROCYSTIS PYRIFERA (LAMINARIALES)1

Juvenile sporophytes of the giant kelp, Macrocystis pyrifera (L.) C. A. Agardh, were transplanted from local kelp beds to stations located various distances from the outfall from an electrical generating station that was known to cause an increase in the settlement of fouling organisms. Plants near the outfall became heavily fouled by the encrusting bryozoan, Membranipora membranacea (L.), and lost about one-third of their blades during the course of the experiment. Blade loss was significantly correlated with amount of fouling. To test the hypothesis that fouling causes blade loss, we paired fouled and unfouled plants of about the same age, overall length, and number of fronds and placed them at stations in nearby kelp beds and near the outfall. At the stations in the kelp beds, the fouled plants lost blades more rapidly than the unfouled controls. However, at the station near the outfall the “control” plants quickly became fouled so there was little difference in treatments and there was no significant difference in blade loss. Plants fouled by Membranipora suffered greater blade loss than clean plants probably because fouled blades are fragile and break off easily and because fish bite off chunks of blade while foraging on the attached bryozoans.     

Experimental effects of kelp canopies on subtidal coralline algae

Plants are often grouped as canopy species or understorey species because it is thought that that these sets of taxa interact in predictable ways. Mensurative experiments in southern Australia demonstrated that the percentage cover of encrusting coralline algae was greater, and articulated (branching) coralline algae less, on boulders under a canopy of dense kelp (>7 plants per m²), Ecklonia radiata, than on boulders without kelp. Experimental clearances of kelp and reciprocal transplants of boulders between patches of E. radiata and patches without kelp showed that canopies maintained and facilitated the growth of encrusting coralline algae and reduced the cover of articulated coralline algae. Potential artefacts associated with clearing kelp and transplanting boulders were not detected when tested with a series of translocation controls. These results reject the model that the co‐occurrence of E. radiata and encrusting corallines is just an assemblage of plants caused by spatial and temporal coincidence. Instead, they support the model that kelp facilitates the growth and survival of understorey algae.     

POLLEN MORPHOLOGY AND ULTRASTRUCTURE OF KRAMERIA (KRAMERIACEAE): UTILITY IN QUESTIONS OF INTRAFAMILIAL AND INTERFAMILIAL CLASSIFICATION

The genus Krameria is currently recognized as an enigmatic, monotypic family of dicotyledons. Previous studies of morphology, anatomy, and cytology have been unable to establish unequivocably its phyletic affinities. We report here the results of an intensive investigation of the pollen of Krameria using light, scanning electron (SEM), and transmission electron microscopy (TEM). Pollen characteristics of the genus were compared to those of all families referred to the Polygalales and to selected species of the Leguminosae-Caesalpinoideae, both groups with which Krameria has historically been allied. Superficially, the pollen of Krameria resembles that of the legumes more than that of genera in the Polygalales. However, in ultrastructure, it differs from the pollen of all taxa investigated from both groups. Within Krameria, several variations of a basic type of 3-colporate pollen are discernible. Species with similar pollen variants appear, on the basis of other morphological data, to represent natural groups within the genus. Nevertheless, an arrangement of groups of species of Krameria from “least” to “most” specialized, based on a logical sequence of modification of the pollen morphology, does not agree with any sequence of specialization using other morphological or ecological characters. It is concluded that pollen morphology and ultrastructure has systematic value for intrafamilial groupings of the Krameriaceae but that palynological modifications are incongruous with trends of specializations of other characters and, like many other lines of investigation, pollen studies do not provide significant data as to the phylogenetic affinities of the family.     

Morphological and molecular concordance of Rhynchozoon clades (Bryozoa, Cheilostomata) from Alaska

Abstract. Alpha‐level taxonomy in the bryozoan order Cheilostomata relies almost exclusively on hard‐part morphology. Geographical, ecophenotypic, and intracolony variation often make it difficult to distinguish intra‐ from interspecific variation and to recognize taxonomically informative characters. DNA sequences provide a source of data independent of morphology by which to gauge the relative reliability of various morphological characters for taxonomy. We present a case study involving a limited number of specimens of Rhynchozoon sp. from Ketchikan, Alaska to show the utility of DNA data in identifying genetic lineages for subsequent morphological analysis. The study illustrates that the use of genetic data need not involve massive, broad‐scale phylogenetic studies to address problems in invertebrate α‐level taxonomy. Phylogeny reconstruction with a 430‐bp fragment of the 16S mitochondrial ribosomal RNA gene showed two moderately diverged clades, here termed Rhynchozoon clades A and B, separated by an average genetic distance of 2.38% (K2P+Γ). Comparison of voucher specimens by scanning electron microscopy showed two congruent, morphologically distinct forms (forms A and B, respectively) distinguishable by a polythetic suite of characters including degree of frontal costation, range of spine number, number of beads on the primary orifice, number of areolar pores, and peri‐orificial sculpturing. Orifice shape and ovicell form proved not to be good diagnostic characters. The status of the two forms as biological species is unclear, although maintenance of distinct suites of morphological characters in the two mitochondrial lineages suggests they may be reproductively isolated from one another. For Rhynchozoon form B, which tends to have a highly costate frontal wall, we suggest a resurrection of the name Rhynchozoon tumulosum, which had been previously synonymized with R. rostratum. Rhynchozoon form A may be conspecific with “Rhynchozoon sp. A” previously reported from Washington state.     

Effects of tidal height and wave exposure on cirrus and penis morphology of the acorn barnacle Tetraclita stalactifera

Exposure to wave action and other environmental factors can alter the morphology of intertidal barnacles. We tested several hypotheses on the causes of morphological variation in the cirri and penises of the barnacle Tetraclita stalactifera at sites differing in wave exposure, at different heights in the intertidal zone, and at different levels of population density. Unlike many other acorn barnacle species, cirrus and penis characteristics did not correspond to differences in wave exposure or crowding. However, barnacles from higher tidal elevations had thicker cirri and thicker penises than those from lower elevations. Because of reduced time submerged at higher elevations, increased thickness may be a means of compensating for reduced feeding and mating opportunity by allowing for continued feeding and mating attempts during periods of greater wave action. Our observations of differences in cirrus and penis morphology suggest that phenotypic plasticity in penis and cirrus characteristics are adaptations shared by the species T. stalactifera and other acorn barnacles, but that T. stalactifera responds differently to environmental stimuli than do other species.