• Energy Research

ABSTRACTTemperature perturbations from climate change affect ecosystems through short‐term pulse events, such as heatwaves, and chronic long‐term shifts. Temperate rocky reef ecosystems have been observed to show substantial ecological change as a result of short‐term temperature fluctuations, but the longer‐term impacts of temperature change remain poorly understood. Here, we investigate temperate reef fishes and mobile invertebrates along Tasmania's east coast, contrasting trends in species richness, abundance, and community structure across seasons within a year to those observed over three decades of warming. Fishes exhibited dynamic seasonal shifts, but interannual changes in richness and abundance balanced out over decades with limited overall net change. In contrast, invertebrate communities changed little seasonally but suffered significant long‐term losses. Our study revealed short‐term ecological changes driven by temperature to be incongruent with long‐term shifts. Species responded in varying ways, depending on life history and ecology. Fishes apparently tracked short temperature pulses, while less mobile invertebrates, such as echinoderms and molluscs, tolerated short‐term fluctuations but exhibited long‐term decline. Multi‐scale studies across a broad range of taxa are needed to clarify thermal responses. The most vulnerable taxa—those facing long‐term thermal stress—may be overlooked through decisions based on short‐term studies, risking major biodiversity loss.

Urbanisation of the coastal zone represents a key threat to marine biodiversity, including rocky reef communities which often possess disproportionate ecological, recreational and commercial importance. The nature and magnitude of local urban impacts on reef biodiversity near three Australian capital cities were quantified using visual census methods. The most impacted reefs in urbanised embayments were consistently characterised by smaller, faster growing species, reduced fish biomass and richness, and reduced mobile invertebrate abundance and richness. Reef faunal distribution varied significantly with heavy metals, local population density, and proximity to city ports, while native fish and invertebrate communities were most depauperate in locations where invasive species were abundant. Our study adds impetus for improved urban planning and pollution management practises, while also highlighting the potential for skilled volunteers to improve the tracking of changes in marine biodiversity values and the effectiveness of management intervention.

Les aires marines protégées (AMP) sont une composante importante et croissante de la stratégie de conservation marine, mais leur efficacité est variable et débattue ; maintenant, une étude a rassemblé des données à partir d'un échantillon mondial d'AMP et démontre que l'efficacité dépend de cinq propriétés clés : si une pêche est autorisée, les niveaux d'application, l'âge, la taille et le degré d'isolement. Les aires marines protégées sont une composante importante et croissante de la stratégie de conservation marine, mais leur efficacité est variable et beaucoup débattue. Ces auteurs rassemblent des données provenant d'un échantillon mondial de régions pêchées et de 87 aires marines protégées et démontrent que l'efficacité d'une aire protégée dépend de cinq propriétés clés : la quantité de pêche autorisée, les niveaux d'application, la durée de la protection, la zone et le degré d'isolement. La conservation n'est assurée que lorsque ces cinq cases ont été cochées. Conformément aux objectifs mondiaux convenus dans le cadre de la Convention sur la diversité biologique, le nombre d'aires marines protégées (AMP) augmente rapidement, mais les avantages socio-économiques générés par les AMP restent difficiles à prévoir et font l'objet de débats1,2. Les AMP ne parviennent souvent pas à atteindre leur plein potentiel en raison de facteurs tels que l'exploitation illégale, les réglementations qui autorisent légalement l'exploitation préjudiciable ou l'émigration des animaux en dehors des limites en raison de l'habitat continu ou de la taille inadéquate de la réserve3,4,5. Ici, nous montrons que les avantages de conservation de 87 AMP étudiées dans le monde augmentent de manière exponentielle avec l'accumulation de cinq caractéristiques clés : pas de prise, bien appliquées, vieilles (>10 ans), grandes (>100 km2) et isolées par l'eau profonde ou le sable. En utilisant des AMP efficaces avec quatre ou cinq caractéristiques clés comme norme non exploitée, les comparaisons des données d'enquête sous-marine des AMP efficaces avec les prévisions basées sur les données d'enquête des côtes pêchées indiquent que la biomasse totale de poissons a diminué d'environ deux tiers par rapport aux références historiques en raison de la pêche. Les AMP efficaces comptaient également deux fois plus d'espèces de poissons de grande taille (>250 mm de longueur totale) par transect, cinq fois plus de biomasse de poissons de grande taille et quatorze fois plus de biomasse de requins que les zones de pêche. La plupart (59 %) des AMP étudiées n'avaient qu'une ou deux caractéristiques clés et n'étaient pas écologiquement distinguables des sites de pêche. Nos résultats montrent que les objectifs mondiaux de conservation basés sur la seule superficie n'optimiseront pas la protection de la biodiversité marine. Il faut mettre davantage l'accent sur une meilleure conception des AMP, une gestion durable et la conformité pour s'assurer que les AMP atteignent la valeur de conservation souhaitée. Las áreas marinas protegidas (AMP) son un componente importante y creciente de la estrategia de protección marina, pero su efectividad es variable y debatida; ahora, un estudio ha reunido datos de una muestra global de AMP y demuestra que la efectividad depende de cinco propiedades clave: si se permite la pesca, los niveles de aplicación, la edad, el tamaño y el grado de aislamiento. Las áreas marinas protegidas son un componente importante y creciente de la estrategia de protección marina, pero su efectividad es variable y muy debatida. Estos autores reúnen datos de una muestra global de regiones pesqueras y 87 áreas marinas protegidas y demuestran que la efectividad de un área protegida depende de cinco propiedades clave: cuánta pesca está permitida, niveles de aplicación, cuánto tiempo ha estado vigente la protección, área y grado de aislamiento. La protección está asegurada solo cuando se han marcado las cinco casillas. En línea con los objetivos mundiales acordados en el marco del Convenio sobre la Diversidad Biológica, el número de áreas marinas protegidas (AMP) está aumentando rápidamente, pero los beneficios socioeconómicos generados por las AMP siguen siendo difíciles de predecir y están siendo objeto de debate1,2. Las AMP a menudo no alcanzan su máximo potencial como consecuencia de factores como la recolección ilegal, las regulaciones que permiten legalmente la recolección perjudicial o la emigración de animales fuera de los límites debido a un hábitat continuo o un tamaño inadecuado de la reserva3,4,5. Aquí mostramos que los beneficios conservadores de 87 AMP investigadas en todo el mundo aumentan exponencialmente con la acumulación de cinco características clave: sin captura, bien aplicadas, antiguas (>10 años), grandes (>100 km2) y aisladas por aguas profundas o arena. Utilizando AMP efectivas con cuatro o cinco características clave como estándar no explotado, las comparaciones de los datos de las encuestas subacuáticas de las AMP efectivas con las predicciones basadas en los datos de las encuestas de las costas pescadas indican que la biomasa total de peces ha disminuido aproximadamente dos tercios de las líneas de base históricas como resultado de la pesca. Las AMP efectivas también tenían el doble de especies de peces grandes (>250 mm de longitud total) por transecto, cinco veces más biomasa de peces grandes y catorce veces más biomasa de tiburones que las áreas de pesca. La mayoría (59%) de las AMP estudiadas tenían solo una o dos características clave y no eran ecológicamente distinguibles de los sitios de pesca. Nuestros resultados muestran que los objetivos de protección global basados en el área por sí solos no optimizarán la protección de la biodiversidad marina. Se necesita más énfasis en un mejor diseño de las AMP, una gestión duradera y el cumplimiento para garantizar que las AMP alcancen el valor de conservación deseado. Marine protected areas (MPAs) are an important and increasing component of marine conservation strategy, but their effectiveness is variable and debated; now a study has assembled data from a global sample of MPAs and demonstrates that effectiveness depends on five key properties: whether any fishing is allowed, enforcement levels, age, size and degree of isolation. Marine protected areas are an important and increasing component of marine conservation strategy, but their effectiveness is variable and much debated. These authors assemble data from a global sample of fished regions and 87 marine protected areas and demonstrate that the effectiveness of a protected area depends on five key properties: how much fishing is allowed, enforcement levels, how long protection has been in place, area and degree of isolation. Conservation is assured only when all five of these boxes have been ticked. In line with global targets agreed under the Convention on Biological Diversity, the number of marine protected areas (MPAs) is increasing rapidly, yet socio-economic benefits generated by MPAs remain difficult to predict and under debate1,2. MPAs often fail to reach their full potential as a consequence of factors such as illegal harvesting, regulations that legally allow detrimental harvesting, or emigration of animals outside boundaries because of continuous habitat or inadequate size of reserve3,4,5. Here we show that the conservation benefits of 87 MPAs investigated worldwide increase exponentially with the accumulation of five key features: no take, well enforced, old (>10 years), large (>100 km2), and isolated by deep water or sand. Using effective MPAs with four or five key features as an unfished standard, comparisons of underwater survey data from effective MPAs with predictions based on survey data from fished coasts indicate that total fish biomass has declined about two-thirds from historical baselines as a result of fishing. Effective MPAs also had twice as many large (>250 mm total length) fish species per transect, five times more large fish biomass, and fourteen times more shark biomass than fished areas. Most (59%) of the MPAs studied had only one or two key features and were not ecologically distinguishable from fished sites. Our results show that global conservation targets based on area alone will not optimize protection of marine biodiversity. More emphasis is needed on better MPA design, durable management and compliance to ensure that MPAs achieve their desired conservation value. تعد المناطق البحرية المحمية (MPAs) مكونًا مهمًا ومتزايدًا في استراتيجية الحفظ البحري، لكن فعاليتها متغيرة ومتناقضة ؛ الآن جمعت دراسة بيانات من عينة عالمية من المناطق البحرية المحمية وتوضح أن الفعالية تعتمد على خمس خصائص رئيسية: ما إذا كان يُسمح بالصيد، ومستويات الإنفاذ، والعمر، والحجم، ودرجة العزلة. تعد المناطق البحرية المحمية مكونًا مهمًا ومتزايدًا في استراتيجية الحفاظ على البيئة البحرية، ولكن فعاليتها متغيرة ومثيرة للجدل. يقوم هؤلاء المؤلفون بتجميع البيانات من عينة عالمية من المناطق المصيدة و 87 منطقة محمية بحرية ويثبتون أن فعالية المنطقة المحمية تعتمد على خمس خصائص رئيسية: مقدار الصيد المسموح به، ومستويات الإنفاذ، وطول مدة الحماية، والمنطقة، ودرجة العزلة. لا يتم ضمان الحفظ إلا عند وضع علامة على جميع هذه الصناديق الخمسة. تماشياً مع الأهداف العالمية المتفق عليها بموجب اتفاقية التنوع البيولوجي، يتزايد عدد المناطق البحرية المحمية (MPAs) بسرعة، ومع ذلك لا تزال الفوائد الاجتماعية والاقتصادية الناتجة عن المناطق البحرية المحمية يصعب التنبؤ بها وتخضع للمناقشة1,2. غالبًا ما تفشل المناطق البحرية المحمية في الوصول إلى إمكاناتها الكاملة نتيجة لعوامل مثل الحصاد غير القانوني، أو اللوائح التي تسمح قانونًا بالحصاد الضار، أو هجرة الحيوانات خارج الحدود بسبب الموائل المستمرة أو عدم كفاية حجم المحمية3، 4، 5. نوضح هنا أن فوائد الحفظ لـ 87 منطقة محمية بحرية تم التحقيق فيها في جميع أنحاء العالم تزداد بشكل كبير مع تراكم خمس ميزات رئيسية: لا تأخذ، تطبق بشكل جيد، قديمة (>10 سنوات)، كبيرة (>100 كيلومتر مربع)، ومعزولة بالمياه العميقة أو الرمال. باستخدام المناطق البحرية المحمية الفعالة مع أربع أو خمس سمات رئيسية كمعيار غير مكتمل، تشير مقارنات بيانات المسح تحت الماء من المناطق البحرية المحمية الفعالة مع التنبؤات المستندة إلى بيانات المسح من السواحل المصيدة إلى أن إجمالي الكتلة الحيوية للأسماك قد انخفض بنحو الثلثين عن خطوط الأساس التاريخية نتيجة لصيد الأسماك. تحتوي المناطق البحرية المحمية الفعالة أيضًا على ضعف عدد أنواع الأسماك الكبيرة (>250 مم إجمالي الطول) لكل مقطع، وخمسة أضعاف الكتلة الحيوية للأسماك الكبيرة، وأربعة عشر ضعف الكتلة الحيوية لأسماك القرش مقارنة بالمناطق التي يتم صيدها. كان لمعظم المناطق البحرية المحمية التي تمت دراستها (59 ٪) سمة رئيسية واحدة أو اثنتين فقط ولم يكن من الممكن تمييزها بيئيًا عن المواقع التي يتم صيد الأسماك فيها. تظهر نتائجنا أن أهداف الحفظ العالمية القائمة على المساحة وحدها لن تحسن حماية التنوع البيولوجي البحري. هناك حاجة إلى مزيد من التركيز على تصميم أفضل للمناطق المحمية البحرية والإدارة الدائمة والامتثال لضمان تحقيق المناطق المحمية البحرية لقيمة الحفظ المطلوبة.

Competition for space between corals and macroalgae represents a key threatening process for coral reefs, yet the influence of climate change on this competitive interaction is poorly understood, particularly at the poleward margins of coral distribution. Here we describe the discovery of Australia’s southernmost hermatypic corals and explore novel dynamics facilitating the presence and extent of high-latitude coral communities. Examination of 607 shallow reef sites across temperate Australia revealed hard corals to be negatively associated with increasing kelp bed cover, but positively associated with increasing sea surface temperature, herbivorous fishes, grazing sea urchins, and increasing cover of turf algae, which proliferates in the absence of kelp. However, the nature of these effects varied across different regions of temperate Australia consistent with regional variability in the presence/absence of key functional groups for temperate reefs, such as guilds of subtropical herbivorous fishes and/or prevalence of overgrazing sea urchins. For the southernmost coral communities, in eastern Bass Strait Tasmania, the dominant reef-building coral Plesiastrea versipora was negatively associated with kelp and positively associated with the southward range-extending diadematid sea urchin Centrostephanus rodgersii, which has caused extensive kelp bed overgrazing since first locally reported in 1974. Facilitation of coral establishment was strongest on overgrazed barrens where urchin density was relatively low, but sufficient to maintain the reef kelp-free, while corals were less frequent at high urchin densities and completely absent from barrens colonised by intensively grazing limpets. In contrast to tropical Australian coral reefs and other temperate regions (e.g. Western Australia), assays of herbivory confirmed sea urchin grazing, not herbivorous fishes, as chiefly responsible for kelp consumption within this high-latitude system. Size structure of P. versipora in eastern Bass Strait was dominated by small colonies (~ 20 cm2), suggesting an expanding population at the poleward edge of the species’ range. Nevertheless, colonies up to a maximum area of 500 cm2 were observed, which are likely > 40 yrs old based on growth rates established in warmer waters. This research highlights novel patterns and processes structuring the interface between subtropical and temperate reef communities under climate change and specifically highlights the role of herbivores in releasing corals from competition with kelp under warming ocean regimes.

Ectotherms generally shrink under experimental warming, but whether this pattern extends to wild populations is uncertain. We analysed ten million visual survey records, spanning the Australian continent and multiple decades and comprising the most common coastal reef fishes (335 species). We found that temperature indeed drives spatial and temporal changes in fish body size, but not consistently in the negative fashion expected. Around 55% of species were smaller in warmer waters (especially among small-bodied species), while 45% were bigger. The direction of a species' response to temperature through space was generally consistent with its response to temperature increase through time at any given location, suggesting that spatial trends could help forecast fish responses to long-term warming. However, temporal changes were about ten times faster than spatial trends (~4% versus ~40% body size change per 1 °C change through space and time, respectively). The rapid and variable responses of fish size to warming may herald unexpected impacts on ecosystem restructuring, with potentially greater consequences than if all species were shrinking.

AbstractThe global extent of macroalgal forests is declining, greatly affecting marine biodiversity at broad scales through the effects macroalgae have on ecosystem processes, habitat provision, and food web support. Networks of marine protected areas comprise one potential tool that may safeguard gene flow among macroalgal populations in the face of increasing population fragmentation caused by pollution, habitat modification, climate change, algal harvesting, trophic cascades, and other anthropogenic stressors. Optimal design of protected area networks requires knowledge of effective dispersal distances for a range of macroalgae. We conducted a global meta‐analysis based on data in the published literature to determine the generality of relation between genetic differentiation and geographic distance among macroalgal populations. We also examined whether spatial genetic variation differed significantly with respect to higher taxon, life history, and habitat characteristics. We found clear evidence of population isolation by distance across a multitude of macroalgal species. Genetic and geographic distance were positively correlated across 49 studies; a modal distance of 50–100 km maintained FST < 0.2. This relation was consistent for all algal divisions, life cycles, habitats, and molecular marker classes investigated. Incorporating knowledge of the spatial scales of gene flow into the design of marine protected area networks will help moderate anthropogenic increases in population isolation and inbreeding and contribute to the resilience of macroalgal forests.Implicaciones del Aislamiento por Distancia de Macroalgas para Redes de Áreas Marinas Protegidas

Marine Protected Areas (MPAs) offer a unique opportunity to test the assumption that fishing pressure affects some trophic groups more than others. Removal of larger predators through fishing is often suggested to have positive flow-on effects for some lower trophic groups, in which case protection from fishing should result in suppression of lower trophic groups as predator populations recover. We tested this by assessing differences in the trophic structure of reef fish communities associated with 79 MPAs and open-access sites worldwide, using a standardised quantitative dataset on reef fish community structure. The biomass of all major trophic groups (higher carnivores, benthic carnivores, planktivores and herbivores) was significantly greater (by 40% - 200%) in effective no-take MPAs relative to fished open-access areas. This effect was most pronounced for individuals in large size classes, but with no size class of any trophic group showing signs of depressed biomass in MPAs, as predicted from higher predator abundance. Thus, greater biomass in effective MPAs implies that exploitation on shallow rocky and coral reefs negatively affects biomass of all fish trophic groups and size classes. These direct effects of fishing on trophic structure appear stronger than any top down effects on lower trophic levels that would be imposed by intact predator populations. We propose that exploitation affects fish assemblages at all trophic levels, and that local ecosystem function is generally modified by fishing.