Bruce A. Marshall

Seep faunas and other indicators of methane‐rich dewatering on New Zealand convergent margins

Abstract Fluid seeps, many marked by rich, distinctive, chemosynthetic faunas living independently of the Earths photosynthesis‐based food chain, are indicators of sedimentological and tectonic processes at convergent margins. Thirteen seep sites, seven marked by distinctive faunas and others marked by carbonate chimneys, carbonate crusts, or plumes of low‐density fluids on sounder records, are reported from the vicinity of the convergent plate boundary through New Zealand. Sites extend from East Cape in the northeast to Otago and Puysegur Ridge in the southwest. Some reports are based on data from fishing and research cruises and some are from archived material. Seeps with different characteristics occur in three geological environments: (1) Calyptogena‐based communites and active plumes occur on upper slope ridges of subduction margins; (2) Maorithyas sp., chimneys, and carbonate crusts occur at shelf edges and canyon heads, often away from subduction margins; (3) Calyptogena sp. and diapirs also occur...

Completeness of the fossil record: Estimating losses due to small body size

Size bias in the fossil record limits its use for interpreting patterns of past biodiversity and ecological change. Using comparative size frequency distributions of exceptionally good regional records of New Zealand Holocene and Cenozoic Mollusca in museum archive collections, we derive first-order estimates of the magnitude of the bias against small body size and the effect of this bias on completeness of the fossil record. Our database of 3907 fossil species represents an original living pool of 9086 species, from which ∼36% have been removed by size culling, 27% from the smallest size class (<5 mm). In contrast, non-size-related losses compose only 21% of the total. In soft rocks, the loss of small taxa can be reduced by nearly 50% through the employment of exhaustive collection and preparation techniques.

Adaptive radiation of chemosymbiotic deep-sea mussels

Adaptive radiations present fascinating opportunities for studying the evolutionary process. Most cases come from isolated lakes or islands, where unoccupied ecological space is filled through novel adaptations. Here, we describe an unusual example of an adaptive radiation: symbiotic mussels that colonized island-like chemosynthetic environments such as hydrothermal vents, cold seeps and sunken organic substrates on the vast deep-sea floor. Our time-calibrated molecular phylogeny suggests that the group originated and acquired sulfur-oxidizing symbionts in the Late Cretaceous, possibly while inhabiting organic substrates and long before its major radiation in the Middle Eocene to Early Oligocene. The first appearance of intracellular and methanotrophic symbionts was detected only after this major radiation. Thus, contrary to expectations, the major radiation may have not been triggered by the evolution of novel types of symbioses. We hypothesize that environmental factors, such as increased habitat availability and/or increased dispersal capabilities, sparked the radiation. Intracellular and methanotrophic symbionts were acquired in several independent lineages and marked the onset of a second wave of diversification at vents and seeps. Changes in habitat type resulted in adaptive trends in shell lengths (related to the availability of space and energy, and physiological trade-offs) and in the successive colonization of greater water depths.

The ark was full! Constant to declining Cenozoic shallow marine biodiversity on an isolated midlatitude continent

Abstract In recent years several authors have questioned the reality of a widely accepted and apparently large increase in marine biodiversity through the Cenozoic. Here we use collection-level occurrence data from the rich and uniquely well documented New Zealand (NZ) shelfal marine mollusc fauna to test this question at a regional scale. Because the NZ data were generated by a small number of workers and have been databased over many decades, we have been able to either avoid or quantify many of the biases inherent in analyses of past biodiversity. In particular, our major conclusions are robust to several potential taphonomic and systematic biases and methodological uncertainties, namely non-uniform loss of aragonitic faunas, biostratigraphic range errors, taxonomic errors, choice of time bins, choice of analytical protocols, and taxonomic rank of analysis. The number of taxa sampled increases through the Cenozoic. Once diversity estimates are standardized for sampling biases, however, we see no evidence for an increase in marine mollusc diversity in the NZ region through the middle and late Cenozoic. Instead, diversity has been approximately constant for much of the past 40 Myr and, at the species and genus levels, has declined over the past ∼5 Myr. Assuming that the result for NZ shelfal molluscs is representative of other taxonomic groups and other temperate faunal provinces, then this suggests that the postulated global increase in diversity is either an artifact of sampling bias or analytical methods, resulted from increasing provinciality, or was driven by large increases in diversity in tropical regions. We see no evidence for a species-area effect on diversity. Likewise, we are unable to demonstrate a relationship between marine temperature and diversity, although this question should be re-examined once refined shallow marine temperature estimates become available.

Second-Order Sequence Stratigraphic Controls on the Quality of the Fossil Record at an Active Margin: New Zealand Eocene to Recent Shelf Molluscs

Abstract New Zealand has the most complete Cenozoic molluscan fossil record in the Southern Hemisphere. In order to understand the true marine faunal history of the region, it is necessary first to identify apparent biodiversity changes that result simply from variations in the quality of the fossil record. The present study uses a range of methods to quantify both long-term, secular changes and short-term patterns of variation in sampling probability for New Zealand Cenozoic shelf molluscs. Overall, about one-third of all once-living Cenozoic species have been sampled, and average per-stage sampling probabilities are between 20% and 50%. Increase in per-stage sampling probability through time reflects the increase in outcrop area and ease of fossil recovery from older to younger stages. Short-term patterns of variation apparently are related to second-order sequence stratigraphic controls of preservation potential. Once the effects of stage duration are eliminated, patterns of stage-to-stage sampling probability reflect enhanced preservation in mid-cycle positions and, perhaps to a lesser extent, secondary post-depositional loss of stratigraphic record above and below sequence boundaries. Although this result mirrors patterns observed in Europe, it is possible that enhanced preservation mid-cycle is relatively more important at active margins, such as New Zealand, whereas secondary loss of record at the sequence boundary is more important at passive margins. Finally, it is worth noting that different methods and data compilations yield rather consistent estimates of short-term variation in sampling probability, lending confidence to the methods and suggesting that the patterns identified are likely to reflect true underlying features of the New Zealand marine fossil record.

Biotic influences on species duration: interactions between traits in marine molluscs

Abstract We analyze relationships among a range of ecological and biological traits—geographic range size, body size, life mode, larval type, and feeding type—in order to identify those traits that are associated significantly with species duration in New Zealand Cenozoic marine molluscs, during a time of background extinction. Using log-linear modeling, we find that bivalves have only a small number of simple, two-way associations between the studied traits and duration. In contrast, gastropods display more complex interactions involving three-way associations between traits, a pattern that suggests greater macroecological complexity of gastropods. This is not an artifact caused by the larger number of gastropods than bivalves in our data set. We used stratified randomized resampling of families to test for associations between traits that might result from shared inheritance rather than ecological trait interactions; we found no evidence of phylogenetic effects in any associations examined. The relationships revealed by our study should serve to constrain the range of possible biological mechanisms that underlie these relationships. As previously observed, two-way associations are present between large geographic range and increased duration, and between large geographic range and large body size, in both bivalves and gastropods. In gastropods, planktotrophic larval type is associated with large range size through a three-way interaction that also involves duration; there is no direct association of larval type and geographic range. Gastropods also display two-way associations between duration and life mode, and duration and feeding type. We note that in gastropods, an infaunal life mode is associated with large range size, whereas in bivalves infaunality is associated with reduced range size.

Sex selective predation of deep-sea, meiobenthic copepods by pectinacean bivalves and its influence on copepod sex ratios

Abstract An alternative hypothesis is presented which accounts for heavily female biased sex ratios in deep‐sea, sediment dwelling, harpacticoid copepods. Deep‐sea, carnivorous bivalves (Mollusca: Pectinacea) are shown to have guts containing an almost exclusive diet of male harpacticoids. Significant removal of males by predation is believed to be responsible for the commonly observed dominance by females in deep‐water assemblages. It is speculated that bioluminescence or chemosensory mechanisms might be implicated in this relationship.

Some Recent Thraciidae, Periplomatidae, Myochamidae, Cuspidariidae and Spheniopsidae (Anomalodesmata) from the New Zealand region and referral of Thraciareinga Crozier, 1966 and Scintillona benthicola Dell, 1956 to Tellimya Brown, 1827(Montacutidae) (Mollusca : Bivalvia)

Thracia vitrea (Hutton, 1873) is redescribed and referred to Thracia Blainville, 1824, subgenus Odoncineta O. G. Costa, 1829. The circum-Antarctic species Thracia meridionalis E. A. Smith, 1885 is newly recorded from New Zealand and referred to subgenus Crassithracia Soot-Ryen, 1941. New thraciids are described belonging to Asthenothaerus Carpenter, 1864 (one), Parvithracia Finlay, 1926 (s. str.) (one), Parvithracia (Pseudoasthenothaerus) Kamanev, 2002 (two) and Trigonothracia Yamamoto & Habe, 1959 (one). Myadora biconvexa Powell, 1927 and Parvithracia cuneata Powell, 1937 are referred to, Barythaerus, a new genus of Thraciidae. Thracia reinga Crozier, 1966 and Scintillona benthicola Dell, 1956 are referred to Tellimya Brown, 1827 in Montacutidae. The periplomatid Pendaloma micans (Hedley, 1901) is newly recorded as widely distributed off New Zealand. New data on shell morphology and distributions are provided for the myochamids Hunkydora novozelandica (Reeve, 1859) and Myochama tasmanica (Tenison Woods, 1877) and new species of Hunkydora Fleming, 1948 and Myadoropsis Habe, 1960 are described. Cuspidaria aupouria Dell, 1950 is referred to Rhinoclama Dall & E. A. Smith in Dall, 1886 (s. str.). A new and minute species of the Cuspidariidae from the Norfolk Ridge is referred to a new genus, namely Pseudogrippina, and cuspidariids belonging in Plectodon Carpenter, 1864 (three) and Rhinoclama (Austroneaera) Powell, 1937 (two) are described. The three Rhinoclama (Austroneaera) species previously recorded from the New Zealand region are reviewed. Spheniopsidae is transferred from Heterodonta to Anomalodesmata and tentatively grouped in Cuspidarioidea. Six new spheniopsids of the genus Grippina Dall, 1912 are described and G. aupouria (Powell, 1937) is redescribed.

Pectinoidea (Mollusca: Bivalvia: Propeamussiidae: Pectinidae) of Lord Howe Island, Norfolk Island and the Kermadec Islands

Abstract Twenty-four pectinoidean species are recorded from Lord Howe Island (7 species), Norfolk Island (13 species) and the Kermadec Islands (14 species). Eighteen species are new records, and these are compared with similar species from the Australasian region. The following taxa are newly synonymised: Annachlamys leopardus rena Iredale, 1939 (= A. kuhnholtzi (Bernardi, 1860)), Chlamys cellularis Oliver, 1915 (= C. c. coruscans (Hinds, 1845)), Chlamys (Mimachlamys) asperrimoides Powell, 1958 (= M. senatoria (Gmelin, 1791)). Chlamydella favus lemchei Powell , 1958 is considered to be specifically distinct from Cyclopecten favus Hedley, 1902, and is referred to Cyclochlamys Finlay, 1926. Lectotypcs are for the following species designated: Hemipecten forbesianus A. Adams & Reeve, 1849, Ostrea senatoria Gmelin, 1791, and Ostrea porphyrea Gmelin, 1791.

New Zealand Recent Hyriidae (Mollusca: Bivalvia: Unionida)

The New Zealand freshwater mussels are taxonomically revised and compared with key Australian and South American taxa using DNA sequence data. Three living species are recognised: Echyridella menziesii, Echyridella aucklandica and Echyridella onekaka. Cucumerunio websteri websteri and Cucumerunio websteri delli, are treated as junior synonyms of Unio aucklandica, which is transferred from Cucumerunio (and Hyridella) to Echyridella. Lectotypes are designated for Unio waikarensis and Unio hochstetteri, which are illustrated together with primary type specimens of other relevant taxa. The type locality of U. aucklandica is restricted to the catchment of the Kawakawa River.