Shifting baselines farther back: Ichthyoliths as palaeo-indicators of fish community structure throughout the Holocene from marginal reefs in Moreton Bay, Australia

Anthropogenic impacts to coastal marine ecosystems have rapidly increased over the past decades in response to rapidly increasing population growth in coastal regions. In Moreton Bay (27º25`S, 152º20`E), Australia, commercial and recreational fishing activities have intensified since the onset of European settlement, nearly 200 years ago. However, the total impacts that these practices have had on fish communities are difficult to discern due to the lack of understanding of long-term historical baselines. To recognise the major drivers of ecological change and degradation of coastal marine ecosystems, whether natural and/or anthropogenic, requires an understanding of the baseline or natural conditions prior to any major anthropogenic exploitation. To determine the baseline conditions of fish community structure in a marine ecosystem, a useful ecological indicator is needed. This study uses microscopic fish teeth as a proxy to reconstruct the baseline structure of fish functional groups in Moreton Bay, Southeast Queensland, Australia, prior to and post European settlement. Fish teeth were picked from core and surface sediments from three sites across Moreton Bay (Wellington Point, Peel Island and Myora Reef) to analyse patterns in temporal and spatial scales of fish functional groups. We found a general increase in the number of fish teeth in more recent sediment samples, highlighting possible taphonomic (preservational) effects. No significant difference in fish community structure was observed among sites in Moreton Bay. However, a significant temporal change in the relative abundance of functional groups was observed: 1) between 0CE to 999CE and 1000CE to 1999CE; and 2) between 2000BCE to 1001BCE and 1000CE to 1999CE. Fishing activities in the past 2000 years in Moreton Bay appear to have had minimal impacts on the functional structure of fish communities; however, the impact of changing environmental conditions, resulting in variation in coral reef accretion, may be a likely factor influencing the changes in functional composition of fish communities through time.


Fishing for evidence: Has catch and effort in Moreton Bay’s recreational fishery been influenced by changing human dimensions and regulatory frameworks?

Time-series of recreational fishing data are lacking for many parts of the world, despite longitudinal monitoring programs being regarded as essential to fisheries management. This study provides the first time-series comparison of catch and effort in Moreton Bay’s mixed-species recreational fishery, focusing on; Sillago maculata (diver whiting), Pagrus auratus (pink snapper), and Portunus armatus (blue swimmer crab). Access-point surveys were undertaken in Moreton Bay in 2013, and compared with surveys conducted using the same methodology in 1994/1995 and 1999. Diver whiting catch rates have significantly declined over the time-series, despite a regulatory change banning this species in commercial trawler bycatch, which was expected to increase productivity and catch rate. Snapper catch rates were consistent between 1994 and 2013, however a significantly greater catch rate in 1999 may have captured a ‘pulse’ increase in snapper abundance. Hyperstability could be occurring in this snapper fishery, with anglers potentially fishing down a declining stock. Size structure of snapper and diver whiting showed greater proportions in larger size classes in 2013 than past years, which for snapper is likely due to restrictive size limits. Mean length of the two species has significantly increased over time. Blue swimmer crabs showed opposite trends, with smaller proportions in larger size classes and a smaller mean carapace width in 2013. Human dimensions of these fisheries were examined in 2013, providing a baseline for future research. This study highlights the importance of time-series comparisons in identifying temporal trends, and may assist in sustainable management of recreational fisheries and fish stocks.


Initial establishment of coral-Symbiodinium association

Reef building corals (Scleractinian) generate habitat structural complexity that supports one of the most diverse marine ecosystems in the world, coral reefs. The success, productivity and growth of Scleractinian corals in oligotrophic tropical seas depends on the successful establishment of symbiosis between coral polyps and dinoflagellate symbionts, as they live in an obligate mutualistic association.

During the last year my field of interest has been the symbiotic association between Scleractinian corals and Symbiodinium dinoflagellates (zooxanthella), especially to understand the complex interactions occur between the holobiont (coral-symbiont) and the environment. This finely balanced symbiotic relationship is highly sensitive to changes in environmental conditions. As such my research has been focused in: (1) describe the environmental factors shaping the distribution Symbiodinium found in broadly distributed species along the Great Barrier Reef (GBR), and (2) evaluate if changes in symbiotic partnership facilitate shifts in thermal tolerance during the early onset of coral-Symbiodinium symbiosis for a common coral specie.

Calcification of the scleractinian coral Goniopora spp. on two inshore reefs of the Great Barrier Reef over the last millennium

Seasonal density banding in coral skeletons offers a unique key to unravelling coral growth through time. Optical densitometry from x-radiographs will be used to calculate annual linear extension and skeletal density – thus calcification – of Goniopora spp. fragments from the coral reef matrix. This pre- industrial revolution baseline, extending back 1000 years, will allow analyses of past, present, and future relationships between environmental stressors and coral growth.


Rare  earth  element  and  heavy  metal  concentrations   in  growth  bands  of  Favia  speciosa  and  Plesiastrea   versipora:  investigating  past  environmental  change   and  anthropogenic  influence  in  Moreton  Bay 

The   marginal   environments   of   Moreton   Bay   are   strongly   effected   by   terrestrial   processes,   with   high   annual   river   discharges   and   sediment   loads,   resulting   in   a   typical   estuarine   type   environment   characterized   by   high   turbidity.   To   explore   the   effects   of   both   anthropogenic   processes   including,   land-­use   change,   urban   and   industrial   growth   and   natural   process   including  ENSO,  rainfall,  weathering  and  sea  level  variation  on  the  environments  of  Moreton   Bay,   the   geochemical   analyses   of   four   massive   corals   from   the   bay   was   conducted.   The   geochemical  analysis  of  annual  growth  bands  of  coral  colonies  of  species  Favia  speciosa  and   Plesiastrea   versipora   using   inductively   coupled   plasma   mass   spectrometry   (ICP-­MS),   allowed   for   the   development   of   a   proxy   record   of   environmental   change   in   Moreton   Bay   spanning   from   1942   to   the   present.   Cores   of   a   Plesiastrea   versipora   from   Peel   Island   and   a   Favia  speciosa  from  Goat  and  Peel  Island  were  collected  on  the  28/6/2011.  A  core  sample  of   a   Favia   speciosa   collected   from   Wellington   Point   in   1997   and   a   fossil   of   the   same   species   from  Cleveland  Point  were  also  incorporated  into  this  study.  Trends  in  trace  metals  (Mn,  Zn,   Sn,  Cu,  Fe,  Pb,  rare  earth  elements,  and  yttrium  concentrations  (La  Ce  Pr  Nd  Sm  Eu  Gd  Tb   Dy   Ho   Er   Tm   Yb   Lu   and   Y)   were   measured,   with   chronologies   developed   from   X-­ray   densitometry   and   U-­Th   dating.   Annual   trends   in   metal   concentration   were   highly   variable,   with   few   long-­term   trends.   Comparisons   of   rare   earth   elements   and   yttrium   (REY)   concentrations   in   coral   cores   from   western   and   eastern   Moreton   Bay   indicated   a   strong   terrestrial-­marine   environmental   gradient   characterized   by   hypo-­saline   turbid   waters   in   western  Moreton  Bay  at  Wellington  Point  to  more  oceanic  water  in  eastern  Moreton  Bay  at   Peel   and   Goat   Island.   Decadal   REY   oscillations   measured   in   P.   versipora   where   predominantly   driven   by   rainfall   variation   in   the   Brisbane   river   catchment,   resulting   in   decadal  trends  of  decreased  river  influence  in  southern  Moreton  Bay  between  1942  and  2011.   Completion   of   Wivenhoe   Dam   in   the   upper   Brisbane   river   catchment   in   1981   resulted   in   a   decrease  in  discharge  variability  of  the  Brisbane  River.  This  is  shown  in  a  drop  in  total  REY    concentrations   in   modern   corals   of   Eastern   Moreton   Bay.   Sea   level   rise   is   also   discussed   as   potential  driver  of  this  decrease.  Mid-­Holocene    (6ka)  Cleveland  point  was  characterized  by   high  river  influence  comparable  with  modern  Wellington  point,  but  with  less  environmental   variability  through  time.  This  study  highlights  the  strong  environmental  gradients  in  the  bay,   driven  by  tidal  currents  and  catchment  process,  and  their  possible  interaction  with  biological   aspects  of  the  Bay,  including  the  potential  for  localized  coral  growth.


Density measurements and calculation of calcification of Goniopora spp. using CT-scan 3D modelization

This study presents a long term record of calcification of Goniopora from the Great Barrier Reef and reveals that calcification rate has been declining for the past 700 years. The significant decrease observed in the mid 19th century corresponds to the European settlement as well as the end of the Little Ice Age. Before this breaking point, calcification is driven by sea surface temperature showing an inverse relationship trend. It is possible that the effect of European settlement on calcification could be explained among other by sedimentation and river discharge. Also the end of the LIA announced drastic changes in temperature. This period is a transition between a cold period and global warming. However the response of corals is still to discover yet.


Project title

Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkable persistence in coral community structure, but little is known of the ecological characteristics of reef communities during periods of low sea stands or sea level falls. We sampled the relative species abundance of coral, benthic foraminifera, and calcareous red algae communities from eight submerged coral reefs in the Huon Gulf, Papua New Guinea, which formed during successive sea level fall and lowstand periods over the past ;416 kyr. We found that dissimilarity in coral species composition increased significantly with increasing time between reef-building events. However, neither coral diversity nor the taxonomic composition of benthic foraminifera and calcareous red algae assemblages varied significantly over time. The taxonomic composition of coral communities from lowstand reefs was significantly different from that of highstand reefs previously reported from the nearby Huon Peninsula. We interpret the community composition and temporal dynamics of lowstand reefs as a result of shifting energy regimes in the Huon Gulf, and differences between low and highstand reefs as a result of differences in the interaction between biotic and environmental factors between the Huon Gulf and Huon Peninsula. Regardless of the exact processes driving these trends, our study represents the first glimpse into the ecological dynamics of coral reefs during low sea level stands when climatic conditions for reef growth were much different and less optimal than during previously studied highstand periods.


Project title

Despite the international and regional protection of white sharks (Carcharodon carcharias), measures fundamental to monitoring their conservation status, population size, genetic population structure and genetic diversity, have not been established. Tissue sourced from predominately juvenile white sharks of five Australian regions was sequenced for the mtDNA control region and genotyped with six nuclear-encoded microsatellite loci. Maternally inherited population structure was found between all regions, suggesting regional natal philopatry, and was also found between the east and south/west coasts, which concords with recent tracking data from satellite and acoustic tags, that indicates the presence of east coast white shark nurseries. Finding genetic population subdivision with both maternally and bi-parentally inherited markers suggests that both genders exhibit degrees of regional philopatry and that males are not panmictic as previously supposed. In contrast, five sharks captured on the east coast proved to have haplotypes that resemble western Indian Ocean sharks more closely than Australian and New Zealand sharks. Estimates of long-term genetic effective population size from microsatellite loci indicate that an extensive ancestral white shark population once existed. Contemporary estimates of genetic effective population size suggest a breeding population in Australian waters greater than commonly accepted thresholds for inbreeding and loss of adaptive potential. However, unmonitored population decline could expose these genetically populations isolated to precipitous loss of genetic diversity. Therefore, we suggest that the current level of international and regional protection of white sharks is appropriate but that populations should be investigated in more detail.