Michael F. Barker

Sexual and asexual reproduction in geographically separated populations of the fissiparous asteroid Coscinasterias calamaria (Gray)

Abstract Sexual reproduction and asexual reproduction by fission were studied in four populations of Coscinasterias calamaria (Gray), two in Otago Harbour in the South Island of New Zealand and two in the North Island near Auckland. The annual reproductive cycle in both islands of New Zealand is clearly defined with a spawning season between November and January. In both sites the pyloric caeca index was approximately inverse to the gonad index cycle as found in other forcipulate asteroids. There are substantial differences in the sex ratios of mature starfish at each site studied, with 1:1 ratios in two populations, one population heavily biased towards females and the fourth consisting almost entirely of males. Morphometric variation in arm number due to splitting was studied and the frequency of splitting varied considerably between the four populations. Generally speaking sublittoral C. calamaria divide less frequently than intertidal starfish and populations in which food is less abundant or of poorer quality are more fissiparous and put less energy into sexual reproduction, than populations with plentiful readily available food in the form of mussels. The significance of the different reproductive patterns in C. calamaria is discussed.

The ecology of Evechinus chloroticus.

This chapter gives an overview of the ecology of Evechinus chloroticus, locally known as “kina,” a ubiquitous echinometrid endemic to New Zealand. Evechinus chloroticus is the most common, largest sea urchins known, with a maximum test diameter of 180–190 cm, occurring on shallow rocky reefs from sheltered sites to those of moderate exposure. Evechinus chloroticus breeds through the spring and summer. Although Evechinus chloroticus has been a traditional food of Maori people since before the arrival of Europeans, the gonads have not yet been harvested extensively for export markets because of poor color and taste. This has proved to be a significant problem in establishing a fishery for this species. The chapter also explores the geographic distribution, habitat, feeding, movement, reproductive cycle, larval development, recruitment, and population and biology associated with Evechinus chloroticus. As the only shallow water sea urchin on hard bottoms around New Zealand, knowledge of its ecology is of great importance.

Adhesive Secretions of Live Mussels Observed in Situ by Attenuated Total Reflection–Infrared Spectroscopy

The chemical species involved in the adhesion of blue mussels (Mytilus galloprovincialis) and greenshell mussels (Perna canaliculus) to surfaces has been investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Mussel spat ranging in size from 0.5 to 25 mm were placed in a flow cell containing a ZnSe multiple internal reflection prism and supplied with temperature-controlled seawater. Distinctively different absorption spectra were obtained when the mussels were predominantly moving across the surface or forming permanent bonds. With limited movement, the absorption spectrum was characteristic of protein with peaks near 1647 cm−1 (amide I), 1543 cm−1 (amide II), and 1235 cm−1 (amide III). When the mussels were observed to be moving across the surface of the ATR-IR crystal there was a strong broad absorption maximum around 1200–900 cm−1 (carbohydrate polymers), presumably due to the secretion of a weakly acidic mucopolysaccharide. Distinct differences in the spectra obtained from the adhesive secretions of blue or greenshell mussels were not observed. The data presented is the first reported use of IR spectroscopy to obtain in situ, real-time, chemical data on the interactions between invertebrates and substrates immersed in sea water.

Is Settlement of Haliotis iris Larvae on Coralline Algae Triggered by the Alga or Its Surface Biofilm

ABSTRACT Abalone larvae settle (attach and metamorphose) in response to crustose coralline algae (CCA), but it is not known whether the settlement cues arise from the CCA or from microbes on their surface. The CCA Phymatolithon repandum induced close to 100% metamorphosis of Haliotis iris larvae. Pebbles and shells with a biofilm but without visible macroalgae induced, on average, 58% metamorphosis on H. iris larvae within 2 days, and biofilms are commonly used to cue settlement in H. iris hatcheries. This suggests that settlement on P. repandum might be triggered by the surface biofilm rather than the CCA itself. Treatment of P. repandum with antibiotics, germanium dioxide, and scrubbing did not significantly reduce settlement of H. iris larvae. Diatom strains isolated from P. repandum induced little attachment or metamorphosis at the low diatom densities (103–104 cells/cm2) found on P. repandum, but induced moderate attachment (30–85% after 4 days) and metamorphosis (2–40%) at high densities (5 × 104-1 × 106 cells/cm2). Nine bacterial strains isolated from P. repandum induced low-percent attachment (0–45% after 7 days) and metamorphosis (0–20%) if assayed in the presence of antibiotics. Parallel assays without antibiotics had higher attachment (40–80% after 7 days) and metamorphosis (5–50%), but this activity may have arisen from bacteria introduced with the larvae. Although bacteria and diatoms did induce some attachment and metamorphosis of H. iris larvae, they were less effective than P. repandum (95% within 2 days). Treatments that greatly reduced the biofilm on P. repandum had no effect on its settlement-inducing activity. This evidence supports the view of CCA as an especially potent source of inducers for temperate abalone larval settlement.

Chapter 16 Ecology of Evechinus chloroticus

Publisher Summary This chapter describes the ecology of Evechinus chloroticus ( E. chloroticus ). It is locally known as “kina” and is a ubiquitous echinometrid sea-urchin endemic to New Zealand. It is one of the largest sea urchins known, with a maximum test diameter (TD) of 16–17 cm. The chapter also describes the morphology and taxonomy of E. chloroticus , which is widely distributed around the main islands of New Zealand and is generally found in water less than 12–14 m deep, although individuals are collected from at least 60 m. E. chloroticus is found in different patterns of distribution and relationships with kelp and other invertebrates throughout New Zealand and it is difficult to make broad generalizations about its habitat. By examining the mouths of urchins in situ and noting the types of food materials present, the feeding of E. chloroticus is observed directly at both Kaikoura and Kaiteriteri. The feeding activity of grazing species is affected by their foraging behavior. Like most species of temperate echinoids, E. chloroticus is gonochoric with a 1:1 sex ratio and an annual breeding cycle—the reproductive effort varying with diet quality and population density.

Chapter 24 – Evechinus chloroticus

Evechinus chloroticus is a large echinometrid sea urchin endemic to New Zealand. It is found aggregated on kelp and/or coralline algae dominated shallow rocky reefs from the far north to the Snares Islands in the south. Juveniles are generally cryptic. Evechinus chloroticus is primarily herbivorous but will graze a variety of encrusting organisms when algae are scarce. Grazing may have a major influence on kelp biomass. Within kelp beds, individuals do not seem to move very far over time periods of up to a year. Evechinus chloroticus is gonochoric with a 1:1 sex ratio. It has an annual breeding cycle with spawning from October to March. Sexual maturity occurs at a test diameter between 35 to 75 mm. Planktotrophic larvae settle after approximately 30 days into coralline algae dominated habitats. Data from calcein-tagged E. chloroticus indicate the Richards model best describes growth, which decreases rapidly after 3 to 4 years (40 to 50 mm test diameter). Annual mortality and mean longevity are highly variable between sites. Potential predators include a number of benthic feeding fish, starfish and lobsters. While gel electrophoresis showed little genetic variation between populations, studies using six microsatellite loci indicate restricted gene flow between North and South Island populations at a scale of > 1000 km. Partial reproductive isolation was observed between the open coast and outer fiord populations, and significant genetic differences were found within and among southern fiords.

Controlling calcium carbonate precipitation in the presence of biological and organic molecules

Biomineralisation arises due to a partnership between the biological and inorganic components of a living system. The final structure and form of the inorganic material is in some way controlled by the nature of the specific organic entities present. This manifests itself in the initiation of the growth, by providing the appropriate matrix in which the inorganic material forms and/or by providing a defect base such that the inorganic crystal packing may be appropriately perturbed. Working with proteins is not necessarily the best or easiest way to understand a physical process and over past years people have turned to simple organic molecules, surfactants, small biological moieties and organic substrates in order to determine, at least in part, the import of organic/inorganic interactions during the growth of the inorganic material. As one example of these additives, surfactants, which represent approximately 50% of the cell membrane, display a diverse and vast array of geometrical forms in aqueous solution, many of which bare striking resemblance to biominerals, albeit on considerably smaller length scales. They also have the ability to associate in solution with inorganic material precursors, such as calcium ions. Hence, while they may not be the main driving force in the formation of biominerals, they are certainly present during the process and may, when used as model systems, allow us some way into the world of nanomaterials. Surfactants, a series of simple alcohols and carboxylic acids, and proteins extracted from the spines of adult sea urchins, have been used by our group to study the formation of calcium carbonate based inorganic materials. The growth of the calcium carbonate is significantly affected by the inclusions, with deviations varying from simple stepped growth to the formation of curved surfaces.

Asexual reproduction and somatic growth of the fissiparous sea star Allostichaster polyplax in New Zealand

ABSTRACT Allostichaster polyplax is a fissiparous (capable of reproducing asexually by fission) sea star found in intertidal and shallow subtidal habitats in New Zealand and Australia. A localized population of A. polyplax occurred at a density of 2.7 individuals m−2 in an intertidal boulder field at Otago Harbour, South Island, New Zealand. The percentage of sea stars undergoing fission, recorded from January 2010 to March 2011, peaked in January (midsummer) in both years. The frequency of fission decreased for larger sea stars (mean arm length, R > 25 mm), suggesting an ontogenic shift from asexual to sexual reproduction. Effects of fission (i.e. arm regeneration) and food availability (small gastropods) on growth, storage and sexual reproduction were examined in a factorial laboratory experiment. There was no effect of arm regeneration or food on total arm growth. Storage capacity, measured as pyloric caeca index (PCI), was greater in full-armed than regenerating sea stars, and greater in fed than starved individuals. Fed individuals had a similar PCI as field-collected ones. Gonads were observed in two individuals (males) in the full-armed and fed treatment. Fission did not occur during the experiment. Feeding rate on snails was greater for full-armed than regenerating sea stars. Water temperature had a weak positive effect on the feeding rate of regenerating sea stars. Our findings suggest that fission and subsequent growth of ramets can sustain demographically stable and geographically isolated populations of A. polyplax. The role of sexual reproduction in population dynamics and connectivity of this species (and fissiparous sea stars in general) remains equivocal and requires further research on genetic differentiation within and among populations.