The Effect of Stormwater Discharge on the Nearshore Benthic Environment of Inner Wellington Harbour

<p>To investigate the spatial and temporal effects of stormwater discharge on the nearshore benthic environment of inner Wellington Harbour, sediment grain size, organic matter content, concentrations of As, Cr, Cu, Ni, Pb and Zn and the presence and abundance of the benthic macrobiota were measured at a number of stations at both stormwater outlets and at control sites. Correlations between the biological and the sedimentological and chemical variables were also investigated. In the vicinity of some outlets the sediment grain size distribution was altered and the sediment organic matter content was up to 5.5 times higher and metal concentrations were up to 11 times higher, than that at control sites. In general organic matter content and metal concentrations were highest close to an outlet and decreased with increasing distance seaward. With increasing distance from outlets the biological communities changed and there were significant differences in one or more of total, polychaete, arthropod and mollusc taxa, polychaete and mollusc individuals, diversity and the abundance of 12 taxa. The spatial extent of the impact of stormwater discharge on the benthic environment ranged from l0 to more than 45 metres from an outlet. Over time the largest range in organic matter content at an outlet was 6.1-42.8% while at a control it was 4-9%. For As, Cu, Pb and Zn the range in concentration over time was larger at stations closer to than those further from the outlet and larger at outlet than control site stations e.g. at 2 m in front of one outlet the Pb concentration range was 25l-1367 ppm, at 20 m from the outlet it was 15-22 ppm and at the associated control site 2 m station it was 15-20 ppm. Over time the direction of change in the biological community was different, and there were significant differences in the number of total, mollusc, polychaete and arthropod taxa and individuals and diversity, between that at the outlet and the associated control site. 27 taxa were more abundant at outlet than control sites and 45 taxa were more abundant at control than outlet sites over time. The biological community at outlet and control sites was best correlated to combinations of 2-5 of the sedimentological/chemical variables. Of these variables, organic matter content was the only commonly occurring variable at outlet sites and did not occur as one of the variables at the control sites. Where the organic matter content was >22% there were a low number of taxa and individuals, and with an increase in organic matter content there was a significant decrease in the number of total and arthropod taxa. The abundance of two taxa was significantly correlated to organic matter content and the abundance of six taxa was significantly correlated to metal concentrations.</p>

The Effect of Stormwater Discharge on the Nearshore Benthic Environment of Inner Wellington Harbour

<p>To investigate the spatial and temporal effects of stormwater discharge on the nearshore benthic environment of inner Wellington Harbour, sediment grain size, organic matter content, concentrations of As, Cr, Cu, Ni, Pb and Zn and the presence and abundance of the benthic macrobiota were measured at a number of stations at both stormwater outlets and at control sites. Correlations between the biological and the sedimentological and chemical variables were also investigated. In the vicinity of some outlets the sediment grain size distribution was altered and the sediment organic matter content was up to 5.5 times higher and metal concentrations were up to 11 times higher, than that at control sites. In general organic matter content and metal concentrations were highest close to an outlet and decreased with increasing distance seaward. With increasing distance from outlets the biological communities changed and there were significant differences in one or more of total, polychaete, arthropod and mollusc taxa, polychaete and mollusc individuals, diversity and the abundance of 12 taxa. The spatial extent of the impact of stormwater discharge on the benthic environment ranged from l0 to more than 45 metres from an outlet. Over time the largest range in organic matter content at an outlet was 6.1-42.8% while at a control it was 4-9%. For As, Cu, Pb and Zn the range in concentration over time was larger at stations closer to than those further from the outlet and larger at outlet than control site stations e.g. at 2 m in front of one outlet the Pb concentration range was 25l-1367 ppm, at 20 m from the outlet it was 15-22 ppm and at the associated control site 2 m station it was 15-20 ppm. Over time the direction of change in the biological community was different, and there were significant differences in the number of total, mollusc, polychaete and arthropod taxa and individuals and diversity, between that at the outlet and the associated control site. 27 taxa were more abundant at outlet than control sites and 45 taxa were more abundant at control than outlet sites over time. The biological community at outlet and control sites was best correlated to combinations of 2-5 of the sedimentological/chemical variables. Of these variables, organic matter content was the only commonly occurring variable at outlet sites and did not occur as one of the variables at the control sites. Where the organic matter content was >22% there were a low number of taxa and individuals, and with an increase in organic matter content there was a significant decrease in the number of total and arthropod taxa. The abundance of two taxa was significantly correlated to organic matter content and the abundance of six taxa was significantly correlated to metal concentrations.</p>

Assessment of Benthic Ecological Quality Status Using Multi-Biotic Indices Based on Macrofaunal Assemblages in a Semi-Enclosed Bay

Semi-enclosed bays have physical and chemical characteristics influenced by both land and sea systems and the quality of the benthic environment is always of great concern. Macrofauna are considered good indicators for evaluating the benthic ecological quality status owing to their biological characteristics. In this study, six biotic indices, namely the Shannon–Wiener diversity index (H′), Abundance-Biomass Comparison (ABC) curve, AZTI’s Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI), BOPA index, and BENTIX index, were used to evaluate the adaptability of different biological indices in the bioassessment of the benthic environment in a semi-enclosed bay. In the annual environmental assessment of the study area, the average values of the six indices (H′, ABC curve, AMBI, M-AMBI, BOPA, and BENTIX) were 4.494, 0.182, 2.433, 0.791, 0.033, and 3.813, respectively; accordingly, H′, M-AMBI, and BOPA met the high standards whereas the other indices met the good standards, indicating that the whole study bay was slightly disturbed and had good ecological quality. From the perspective of spatial variation, the benthic environment in the middle of the bay was better than that in the north; the environmental problems in the northeast were particularly noteworthy. In terms of temporal patterns, the benthic environment in winter and summer was significantly better than that in spring and autumn, with obvious seasonal differences. The present results indicate that the H′ and ABC curve based on benthic abundance and biomass should be avoided for environmental assessment in mariculture areas. AMBI and M-AMBI should be used with caution when the percentage of unassigned species is high, in which case H′ is the appropriate choice. When there are few unassigned species, M-AMBI is more conducive for accurate evaluation of the benthic environment than AMBI and H′.

Macrobenthic Assessment of the South Sandwich Islands Reveals a Biogeographically Distinct Polar Archipelago

The sub-Antarctic South Sandwich Islands forms part of one of the largest marine protected areas (MPAs) in the world. Whilst the neighbouring island of South Georgia is known to be a biodiversity hotspot, very little was known about the benthic biodiversity or biogeography of the South Sandwich Islands. Here we present findings from the first biophysical assessment of this polar archipelago. Using open-access datasets, alongside results from a recent UK Government-funder Blue Belt expedition to the region, we assess how the island’s biodiversity is structured spatially and taxonomically and how this is driven by environmental factors. The South Sandwich Islands are shown to be both biologically rich, and biogeographically distinct from their neighbouring provinces. A gradient forest approach was used to map the archipelago’s benthic habitats which, based on the functional composition of benthic fauna and environmental characterisation of the benthic environment, demonstrated a distinct biogeographical north-south divide. This faunal and environmental discontinuity between the South Sandwich Islands and the rest of the MPA and between the different islands of the archipelago itself, highlights the importance of the zoned protection across the South Georgia and South Sandwich Islands Marine Protected Area.

Macroinvertebrate interactions stimulate decomposition in WWTP effluent-impacted aquatic ecosystems

Aquatic ecosystems worldwide are impacted by an influx of nutrients and sludge particles from wastewater treatment plant (WWTP) effluents, leading to a degradation of benthic habitats and a loss of associated macroinvertebrate taxa. Hence, in habitats impacted by WWTPs, only a few tolerant macroinvertebrate taxa remain. These tolerant detritivore macroinvertebrate taxa play an important role in the degradation of organic matter, and biotic interactions between these taxa may either enhance or reduce the rate of sludge degradation. Therefore, the aim of the present study was to examine if the interaction between asellids and tubificids, both highly abundant in systems impacted by WWTP effluent, enhances the degradation of sludge. To this end, growth and reproduction of both taxa, sludge degradation and nutrient concentrations in the overlying water were measured in a 28-day laboratory experiment, subjecting WWTP sludge to 4 treatments: a control without macroinvertebrates, a tubificid, an asellid, and an asellid + tubificid treatment. Sludge degradation, phosphate concentration in the overlying water and asellid reproduction were enhanced when asellids and tubificids were jointly present, whereas tubificid growth and reproduction were hampered in comparison to the tubificid treatment. Hence, our results suggest that the biotic interactions between these tolerant detritivores stimulate sludge degradation, and thus possibly mitigating the negative impacts of WWTP-derived sludge particles on the benthic environment.

Distribution of Vulnerable Marine Ecosystems at the South Sandwich Islands: Results From the Blue Belt Discovery Expedition 99 Deep-Water Camera Surveys

The South Sandwich Islands (SSI) are a chain of volcanic islands located to the east of the Scotia Sea, approximately 700 km south-east of South Georgia. To date, knowledge of the SSI benthic environment remains limited. In this context, the Blue Belt Programme conducted a scientific survey in the SSI Marine Protected Area (MPA) during February/March 2019 to examine the biodiversity and distribution of benthic communities and their potential vulnerability to licensed longline research fisheries. Here we report results from analysis of multibeam echosounder (MBES) data and drop camera imagery data collected in selected locations around the SSI. A total of eight vulnerable marine ecosystem (VME) indicator morphotaxa were mapped along the slopes of the SSI, showing a substantial variation in taxon composition and frequency of occurrence, both along bathymetric and latitudinal gradients. Our results suggest that VME indicator taxa are mostly restricted to waters shallower than 700 m. As such, based on our present understanding of the region’s benthic environment the MPA, as currently established, offers effective protection for the majority of the VME indicator taxa.

Identification of Leucinostatins from Ophiocordyceps sp. as Antiparasitic Agents Against Trypanosoma cruzi

Safe and effective treatments for Chagas disease, a potentially fatal parasitic infection associated with cardiac and gastrointestinal pathology and caused by the kinetoplastid parasite Trypanosoma cruzi, have yet to be developed. Benznidazole and nifurtimox, which are currently the only available drugs against T. cruzi, are associated with severe adverse effects and questionable efficacy in the late stage of the disease. Natural products have proven to be a rich source of new chemotypes for other infectious agents. We utilized a microscopy-based high-throughput phenotypic screen to identify inhibitors of T. cruzi from a library of natural product samples obtained from fungi procured through a Citizen Science Soil Collection Program (https://whatsinyourbackyard.org/), and the Great Lakes (USA) benthic environment. We identified five leucinostatins (A, B, F, NPDG C and NPDG D) as potent inhibitors of the intracellular amastigote form of T. cruzi. Leucinostatin B also showed in vivo efficacy in a mouse model of Chagas disease. Given prior reports that leucinostatins A and B have antiparasitic activity against the related kinetoplastid T. brucei, our findings suggest a potential cross-trypanocidal compound class and provide a platform for further chemical derivatization of a potent chemical scaffold against T. cruzi.