-- Layton et al. Chemical microenvironments within macroalgal assemblages: implications for the inhibition of kelp recruitment by turf algae. Limnology & Oceanography. DOI:10.1002/lno.11138 -- Kelp forests around the world are under increasing pressure from anthropogenic stressors. A widespread consequence is that in many places, complex and highly productive kelp habitats have been replaced by structurally simple and less productive turf algae habitats. Turf algae habitats resist re-establishment of kelp via recruitment inhibition; however little is known about the specific mechanisms involved. One potential factor is the chemical environment within the turf algae and into which kelp propagules settle and develop. Using laboratory trials, we illustrate that the chemical microenvironment (O2 concentration and pH) 0.0–50 mm above the benthos within four multispecies macroalgal assemblages (including a turf-sediment assemblage and an Ecklonia radiata kelp-dominated assemblage) are characterised by elevated O2 and pH relative to the surrounding seawater. Notably however, O2 and pH were significantly higher within turf-sediment assemblages than in kelp-dominated assemblages, and at levels that have previously been demonstrated to impair the photosynthetic or physiological capacity of kelp propagules. Field observations of the experimental assemblages confirmed that recruitment of kelp was significantly lower into treatments with dense turf algae than in the kelp-dominated assemblages. We demonstrate differences between the chemical microenvironments of kelp and turf algae assemblages that correlate with differences in kelp recruitment, highlighting how degradation of kelp habitats might result in the persistence of turf algae habitats and the localised absence of kelp.

Comprehensive baseline environmental data for Storm Bay in south eastern Tasmania were required to inform the salmonid industry regarding site selection, to provide background environmental data before large-scale farming commences, and to support the development of a scientifically relevant and cost-effective environmental monitoring program. Storm Bay is a large deep bay that receives freshwater inflow from the River Derwent on its north-western boundary and exchanges water with Frederick Henry Bay on its north-eastern boundary. The eastern and western boundaries are defined by the Tasman Peninsula and Bruny Island, respectively, and the southern boundary connects with the Tasman Sea. This area is a mixing zone between the River Derwent outflow and oceanic waters. The oceanography in Storm Bay is complex and is characterized by considerable fluctuations in temperature, salinity and nutrients on variable temporal and spatial scales. This is due to the southerly extension of warm nutrient-depleted sub-tropical waters transported via the East Australian Current (EAC) down the east coast of Tasmania over summer, whilst the south and south-west coasts are influenced by cooler, nutrient-rich sub-Antarctic waters from the south and the Leeuwin Current from the north-west (Buchanan et al. 2014). The current project arose in response to the salmon aquaculture industry recognising the need for increased scientific knowledge to support ecologically sustainable development of Atlantic salmon (Salmo salar) farming operations in south-eastern Tasmania, particularly expansion into Storm Bay. The information provided will assist salmon companies to manage their operations in Storm Bay under varying environmental conditions. Our research has also provided the opportunity to investigate changes in water quality over a quarter of a century, as CSIRO investigated seasonal and inter-annual variability in chemical and biological parameters in Storm Bay during 1985-89. We sampled at the same “master station” in Storm Bay as CSIRO and used similar procedures where possible. Five sites were sampled monthly in Storm Bay for over five years from November 2009 to April 2015, except on rare occasions when weather conditions were unsuitable, and bimonthly at times in 2013 when external funding was not available. Site 1 was located at the mouth of the Derwent estuary and the entrance to Storm Bay, site 2 was in the same location as the ‘master site’ of a CSIRO study in 1985-88, site 3 was furthest offshore and provided the most information on oceanic currents influencing the bay, while sites 5 and 6 were requested by the salmon aquaculture industry as potential sites for expansion of salmon farming. Site 4 was further offshore and monitoring at this site was discontinued after three months because of insufficient time to collect samples from all sites in one day. An additional site, 9, at the entrance to Frederick Henry Bay was included from 18 July 2011 at the request of the Marine Farming Branch, Department of Primary Industries, Parks, Water and Environment (DPIPWE), to provide information on water quality coming from Frederick Henry Bay. Adjacent to, and largely unaffected by the River Derwent, Frederick Henry Bay is a large marine embayment with limited freshwater input from the Coal River at its northern boundary. ---------------------------------------------- See child records linked to this parent record for specific context and methodologies for each of the monitoring variables (phytoplankton, zooplankton, chlorophyll, pigment, nutrients, oceanography).

Data is PCR amplification results of southern rock lobster (Jasus edwardsii) faecal material tested for sea urchin DNA (using unique primers for Centrostephanus rodgersii and Heliocidaris erythrogramma) in an attempt to determine in situ rates of consumption of sea urchins by lobsters. An efficient and non-lethal method was used to source and screen lobster faecal samples for the presence of DNA from ecologically important sea urchins. Lobster faecal samples were collected from trap caught specimens sourced in winter & summer seasons over 2 years (2009-2011) within two no-take research reserves; declared specifically for the purpose of rebuilding large predatory-capable lobsters to assess the potential for predator-driven remediation of kelp beds on rocky reefs extensively overgrazed by sea urchins (North Eastern Tasmania) and reefs showing initial signs of overgrazing (South Eastern Tasmania). Data for molecular assays showed high variability in the proportion of lobsters testing positive to sea urchins, with significant variability detected across different years and seasons but this was found to vary depending on different lobster size-classes. Sea urchin DNA was also amplifiable from sediments and urchin faeces collected from the reef surface where urchins occurred in high abundance. Furthermore, positive sea urchin DNA assays were obtainable from lobster faeces after lobsteres were fed sediment and urchin faecal material. Rates of predation obtained with genetics tests can also be compared to independent rates of urchin losses given known lobster abundances within research reserves (and at control sites). Data of changes in urchin abundances and lobster abundances are therefore also lodged as part of this record.

Gillnet fishing trials at a number of sites off the east coast of Tasmania have been undertaken to collect samples of the banded morwong, which are characterised based on size, age, maturity stage and sex structure. Otoliths are sectioned for age determination. The dataset comprises a major component of work carried out from the beginning of 2001 and available historic data (1995 to 2000) have also been uploaded into this database to provide a complete dataset. See attached reports for further information.

Surveys were conducted as part of an assessment of the Macrocystis pyrifera (Linnaeus) C. Agardh 1820 beds on the east coast of Tasmania by the Commonwealth Scientific and Industry Research Organization (CSIRO) Division of Fisheries seaweed program in the early 1950's. Surveys were conducted because of interest in the Macrocystis beds as a source of alginates. Surveys were done between 1950 and mid 1953. The paper was published in 1954.

Mesozooplankton community composition and structure were examined throughout the D’Entrecasteaux Channel, Huon Estuary and North West Bay, Tasmania, from November 2004 to October 2005, the data represented by this record was collected on the 07/12/2004 The composition of the mesozooplankton community was typical of inshore, temperate marine habitats, with seasonally higher abundance in summer and autumn and lower numbers in winter and spring. Copepods were the largest contributors to total abundance across all seasons and stations, while cladocerans and appendicularians were proportionally abundant in spring and summer. The faecal pellets of these three main groups, along with those of krill and amphipods, also contributed significantly to material recovered from sediment traps. Meroplanktonic larvae of benthic animals showed short-term peaks in abundance and were often absent from the water column for long periods. Spatially, North West Bay and the Channel had a higher representation of typically marine species, including Calanus australis and Labidocera cervi, while truly estuarine species, such as the copepod Gladioferens pectinatus, were more important in the Huon Estuary.

Water temperature, averaged across the water column, in Storm Bay followed a distinct seasonal cycle each year, reaching a low of 9 °C and a high of ~ 19 °C. Warmest temperatures were in February, followed by a gradual cooling throughout autumn to a winter minimum in August, then increasing again during spring. Across the sites, the median temperature varied little, with site 3, the most marine of the sites, showing the least spread in values. Median salinity varied little across Storm Bay, being slightly higher at sites 3 and 6, highlighting the marine nature of site 3 and the patterns of seawater circulation in Storm Bay. The lowest salinities were recorded at site 1, where less saline surface waters flow into the bay from the Derwent Estuary. Seasonally, salinity was highest in autumn, with slightly fresher water present in Storm Bay in spring. Some lower salinity values were recorded in July and August, suggesting the presence of less saline subantarctic water flowing into the bay, or freshwater flow from the Derwent. Glider transects show slight lower salinity in summer, then mild stratification in autumn to spring, especially in the shallow regions near the mouth of the Derwent.

The Tasman Fracture CMR AUV survey was a pilot study undertaken in 2014/15 as part of the National Marine Biodiversity Hub's National monitoring, evaluation and reporting theme. The aim of this theme is to develop a bluepint for the sustained monitoring of the South-east Commonwealth Marine Reserve Network. The particular aim of the survey was to contribute to an inventory of the distribution and cover of epibenthic biota in the reserve using IMOS AUV 'Sirius'. Data contained here represents a scored subset of the ~ 18,400 images collected at the Tasman Fracture CMR. Images were scored for proportion cover of visible macrobiota using 25 random points superimposed on each image. Taxon were biologically classified using UTAS morphospecies classification scheme, which can be mapped back to CATAMI (http://catami.org/).

The data is quantitative abundance of fish, megafaunal invertebrates and percent algal cover derived from underwater visual census methods involving transect counts at rocky reef sites around Tasmania. This dataset allows examination of changes in Tasmanian shallow reef faunal and floral communities over a decadal scale, with initial surveys conducted in 1992-1995, and again in 2006-2007. There are plans for ongoing surveys. An additional component was added in the latter study - a boat ramp study looking at the proximity of boat ramps and their effects of fishing. We analysed underwater visual census data on fishes and macroinvertebrates (abalone and rock lobsters) at 133 shallow rocky reef sites around Tasmania that ranged from 0.6 - 131 km from the nearest boat ramp. These sites were not all the same as those used for the comparison of 1994 and 2006 reef communities. The subset of 133 sites examined in this component consisted of only those sites that were characterized by the two major algal (kelp) types (laminarian or fucoid dominated). Sites with atypical algal assemblages were omitted from the 196 sites surveyed in 2006. This study aimed to examine reef community data for changes at the community level, changes in species richness and introduced species populations, and changes that may have resulted from ocean warming and fishing. The methods are described in detail in Edgar and Barrett (1997). Primarily the data are derived from transects at 5 m depth and/or 10 m depth at each site surveyed. The underwater visual census (UVC) methodology used to survey rocky reef communities was designed to maximise detection of (i) changes in population numbers and size-structure (ii) cascading ecosystem effects associated with disturbances such as fishing, (iii) long term change and variability in reef assemblages.

An aerial survey was conducted for giant kelp (Macrocystis pyrifera) on the east coast of Tasmania from Eddystone Point to Southeast Cape. This survey represents part of a series of similar surveys, with historic aerial surveys having been conducted in 1986 and 1999. The survey was conducted via light aircraft. Areas of visable Macrocystis pyrifera beds were marked on topographical land tenure maps using landmarks as references, and complimentary photo footage was collected.