2016 SoE Marine Chapter - State and Trends - Trophic structures and relationships

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "The state and trends of ecological processes – trophic structures and relationships". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.----------------------------------------DESCRIPTION OF ECOLOGICAL PROCESS FOR EXPERT ASSESSMENTFor this assessment, food web structure and function as defined by diet and modelling studies (which synthesis much of the available information) have been used to evaluate the status and trends for trophic structures and relationships. The status and outlook for the structure of Australian marine ecosystems is highly variable. Food webs are naturally dynamic, through time and space (e.g. Griffiths et al. 2009), and human pressure on them has varied around Australia over the past two centuries, altering trophic structures to differing degrees (Dell et al. 2013, GBRMPA 2014). Food webs studies have primarily focused on coastal and shelf waters (e.g. Salini et al 1998, Bulman et al. 2001, DofWWA 2009), with much less coverage of deep water food webs. Diet studies have only occurred intermittently and few studies have been subsequently repeated (e.g. recent resampling of fish diets on the shelf of SE Australia; CSIRO unpublished). Consequently, understanding the true magnitude of inter-annual variation in diets is low and there is little capacity to be sure of dietary changes through time.Modelling studies (Fulton et al. 2005, Klaer 2005) suggest there has been trophic restructuring of food webs in south-eastern Australia over the last century, particularly as a result of the intensification of commercial fisheries up to the 1990s. The reduction in fishing pressure, particularly over the last 5-10 years (Flood et al. 2014, Patterson et al. 2015) will likely, eventually, allow the recovery of trophic structures. However, a complete recovery is unlikely given the multitude of on-going pressures (e.g. remaining fishing pressure, both recreational and commercial, shipping, coastal habitat modification, pollution, etc.) and because some highly depleted species (e.g. eastern gemfish) have failed to recover from past overexploitation; which itself may be related to shifts in trophic connections with predators and prey (TSSC 2009). In addition, climate change is reshaping south eastern ecosystems, with shifts in species ranges (Sunday et al. 2015) and the realisation of new trophic interactions (e.g. shifts in octopus diets; Briceno et al. 2015), as omnivorous species appear to shift more rapidly than carnivores (Sunday et al. 2015). Eastern Australian ecosystems, including the Great Barrier Reef are highly modified (Butler and Jernakoff 1999, GBRMPA 2014). Amongst the most obviously shifted systems are around population centres and in the southern Great Barrier Reef (GBRMPA 2014). As elsewhere, fishing pressure has eased over the past 5 years, but other pressures (e.g. from increasing development) have increased (AIMS 2014). Overall trophic structures likely remain highly modified, both by past and present removal of predatory species and shifts in abundance of basal species, due to eutrophication or habitat removal (GBRMPA 2014, Fulton and Gorton 2014). The ecosystems of northern, western, southwestern and southern Australia see less direct, and spatially more variable, pressure than those in the east and south east. Over the past 3 decades, fishing pressure in the region has significantly declined, and has continued to do so (though at a reduced rate) over the past 5 years (Prince et al. 2008, Patterson et al. 2014, Fletcher and Santoro 2015). Development of other sectors (e.g. shipping) has grown, but largely concentrated on specific locations (AIMS 2014). Consequently, some locations will remain highly modified (e.g. where there is heavy cumulative pressure, due to the combined effects of catchment and urban outflow, shipping, tourism, fisheries, etc), while food webs in remote locations (or those primarily influenced only by sustainable fisheries, such as in the Great Australian Bight) may be stable and in good condition. Shifting climate drivers (e.g. marine heatwaves) are likely to be effecting trophic interactions (e.g. via declines in kelp shifts in fish communities; Wernberg et al. 2013), but there is too little data to be certain of the true status and trends.DATA STREAM(S) USED IN EXPERT ASSESSMENTDiet data from south east and western Australia as well as information published in peer reviewed publications and reports. Details of the specific data sets used to generate the assessment have not been provided.----------------------------------------2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]• 2016 •Assessment grade: Poor-GoodAssessment trend: UnclearConfidence grade: Adequate high quality evidence or high level of consensusConfidence trend: Adequate high quality evidence or high level of consensusComparability: Grade and trend are comparable to the 2011 assessment• 2011 •Assessment grade: GoodAssessment trend: StableConfidence grade: Limited evidence or limited consensusConfidence trend: Limited evidence or limited consensus----------------------------------------CHANGES SINCE 2011 SOE ASSESSMENTDiet studies have only occurred intermittently and few studies have been subsequently repeated (e.g. recent resampling of fish diets on the shelf of SE Australia; CSIRO unpublished). Consequently, understanding the true magnitude of inter-annual variation in diets is low and there is little capacity to be sure of dietary changes through time. As a result trends cannot be considered to be stable and can only be regarded as unclear.

2016年《环境状况报告》（State of the Environment, 以下简称SoE）的海洋章节整合了多套基于海洋数据流（Data Stream）构建的专家模板。本元数据记录旨在说明题为《生态过程的状况与趋势——营养结构与相互关系》的专家评估报告。本记录附带完整的专家评估报告（含已提供的图表与表格）。若有可用数据，生成该专家评估所用的数据流（Data Stream）可通过本记录的“在线资源（On-line Resources）”板块获取。
----------------------------------------专家评估生态过程说明
本次评估以摄食研究与模型研究（整合了绝大多数可获取的信息）所界定的食物网结构与功能为依据，对营养结构与相互关系的现状及趋势进行评估。澳大利亚海洋生态系统结构的现状与前景存在显著差异。食物网在时间与空间维度上本就具有天然动态性（如Griffiths等人2009年的研究）；过去两个世纪以来，澳大利亚各地人类对食物网施加的压力存在差异，导致营养结构出现不同程度的改变（Dell等人2013年、大堡礁海洋公园管理局（Great Barrier Reef Marine Park Authority, 以下简称GBRMPA）2014年的研究）。现有食物网研究主要集中于近岸与陆架海域（如Salini等人1998年、Bulman等人2001年、西澳大利亚州渔业与海洋部（Department of Fisheries and Western Australian Waters, 以下简称DofWWA）2009年的研究），对深水食物网的研究覆盖度则相对较低。摄食研究仅断断续续开展，且鲜有研究得到重复验证（例如近期对澳大利亚东南部陆架海域鱼类摄食情况的重采样研究；联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, 以下简称CSIRO）未刊研究）。因此，当前对摄食状况年际变化真实幅度的认知仍较为有限，难以准确判断摄食状况随时间的变化趋势。
模型研究（Fulton等人2005年、Klaer 2005年的研究）显示，过去一个世纪以来澳大利亚东南部海域的食物网已出现营养结构重组，这一变化主要源于截至20世纪90年代的商业渔业强度提升。捕捞压力的降低（尤其是过去5至10年间的压力下降，Flood等人2014年、Patterson等人2015年的研究）最终或可推动营养结构的恢复。但鉴于当前仍存在多种持续施加的压力（如尚存的休闲与商业捕捞压力、航运活动、近岸生境改造、污染等），且部分严重枯竭的物种（如东部宝石鱼）尚未从过去的过度捕捞中恢复（这一情况或与其与捕食者、猎物间的营养联系变化有关；联邦濒危物种威胁咨询委员会（Threatened Species Scientific Committee, 以下简称TSSC）2009年的研究），因此完全恢复的可能性极低。此外，气候变化正在重塑澳大利亚东南部的生态系统：物种分布范围发生迁移（Sunday等人2015年的研究），新的营养相互关系逐渐形成（例如章鱼摄食习惯的改变；Briceno等人2015年的研究），而杂食性物种的分布迁移速度似乎快于肉食性物种（Sunday等人2015年的研究）。
包括大堡礁在内的澳大利亚东部海域生态系统已遭到严重改造（Butler与Jernakoff 1999年、GBRMPA 2014年的研究）。受影响最显著的生态系统集中于人口聚居区附近海域以及南部长堡礁海域（GBRMPA 2014年的研究）。与其他区域一样，过去5年间东部海域的捕捞压力有所缓解，但其他压力（如开发活动加剧带来的影响）却有所上升（澳大利亚海洋科学研究所（Australian Institute of Marine Science, 以下简称AIMS）2014年的研究）。总体而言，由于过去和当前的捕食性物种移除活动，以及富营养化或生境破坏导致的基础物种种群数量变化，东部海域的营养结构可能仍处于严重改造状态（GBRMPA 2014年、Fulton与Gorton 2014年的研究）。
澳大利亚北部、西部、西南部与南部海域的生态系统所受的直接压力低于东部与东南部海域，且压力的空间异质性更强。过去30年间，该区域的捕捞压力已显著下降，且在过去5年间仍在持续降低（尽管下降速率有所减缓；Prince等人2008年、Patterson等人2014年、Fletcher与Santoro 2015年的研究）。其他行业的开发活动（如航运）有所增长，但主要集中于特定区域（AIMS 2014年的研究）。因此，部分区域仍将处于高度改造状态（例如因流域径流、城市排污、航运、旅游业、渔业等多重因素叠加导致压力巨大的海域），而偏远海域（或仅受可持续渔业影响的区域，如大澳大利亚湾）的食物网则可能保持稳定且处于良好状态。气候变化驱动因子的变化（如海洋热浪）或已对营养相互关系造成影响（例如通过海藻减少导致鱼类群落结构改变；Wernberg等人2013年的研究），但当前数据不足，无法准确判断其真实状况与趋势。
----------------------------------------专家评估所用数据流
本次评估所用的数据包括澳大利亚东南部与西部海域的摄食数据，以及已发表于同行评议期刊与报告中的相关信息。生成本评估所用的具体数据集细节尚未提供。
----------------------------------------2016年SoE评估摘要【完整细节请参阅附带的专家评估报告】
• 2016年
评估等级：较差-良好
评估趋势：不明确
置信等级：具备充分高质量证据或高度共识
置信趋势：具备充分高质量证据或高度共识
可比性：本次评估的等级与趋势可与2011年评估结果进行对比

• 2011年
评估等级：良好
评估趋势：稳定
置信等级：证据有限或共识不足
置信趋势：证据有限或共识不足

----------------------------------------2011年SoE评估以来的变化
摄食研究仅断断续续开展，且鲜有研究得到重复验证（例如近期对澳大利亚东南部陆架海域鱼类摄食情况的重采样研究；CSIRO未刊研究）。因此，当前对摄食状况年际变化真实幅度的认知仍较为有限，难以准确判断摄食状况随时间的变化趋势。据此，无法认定评估趋势处于稳定状态，仅能判定其趋势不明确。