Fisheries management at the tri-national border between Belize,Guatemala and Honduras

The Mesoamerican Barrier Reef System has considerably changed after a series of natural disturbances, especially hurricanes and extreme coral bleaching, and is further impacted by anthropogenic threats. Located at a tri-national border between Belize, Guatemala and Honduras, the Sapodilla Cayes Range is specifically impacted by tourism, commercial fishing and other anthropogenic activities occurring in the three countries and by the fact that Belize only claims 3 nautical miles of Exclusive Economic Zone in the south pending a settlement to a border dispute with Guatemala. This area represents a source of income and food to several coastal communities and to Belize's economy. Key fisheries products harvested in the area by the three countries are the same but fisheries legislations and the number of fishermen are different, creating conflicts between fishermen. This paper summarizes the key problems that arise in southern Belizean fishing waters and the efforts made by the three countries to ensure the sustainability of the fishery.     

The value of recreational fishing in the Great Barrier Reef, Australia: A pooled revealed preference and contingent behaviour model

Given the focus on protecting natural assets in the Great Barrier Reef Marine Park in Australia, it is important for managers and policy makers to understand the value of recreational fishing in the area, and how changes in management may affect those recreational values. Travel cost methods were used to estimate the value of recreational fishing in the Capricorn Coast in Central Queensland using data from on-site surveys conducted at boat ramps. The study also uses contingent behaviour models to estimate the change in the value of recreational fishing as conditions vary. Results indicate that there are high values associated with recreational fishing activity along the Capricorn Coast, and that the demand for recreational fishing is inelastic and that values are relatively insensitive to changes in catch rates.     

十万大山盆地下二叠统生物礁古油藏剖析及其地下隐伏礁的分布预测

广西宁明亭亮茅口组生物礁古油藏为十万大山盆地已暴露破坏的礁石油藏之一。亭亮生物礁为大新（崇左）台地边缘发展起来的大型堤礁。礁的主要造架生物为海绵、水螅、苔藓虫及藻类等，其沉积组合具礁基、礁核、礁盖、礁间滩及礁前等亚相。该石油藏的含沥青储层主要位于礁体的上部和顶部，含沥青礁灰岩厚达９８ｍ以上。礁储层次生溶孔的形成与分布主要受控于深埋有机溶蚀作用，同时在空间上还与礁顶部古风化壳和不整合面密切相关。烃源     

塔中地区礁滩储集体形成条件及分布规律

奥陶纪时期，塔中地区发育生物礁、丘和滩等不同类型的碳酸盐岩建隆生物礁丘发育层位主要集中在上奥陶统．塔中地区的礁滩相包括灰泥丘、中物礁、粒屑滩和地质异常体等4种类型，沉积古地理、构造作用、陆源碎屑物注入和海平面变化是控制生物礁发育的主要因素．塔中地区生物礁的分布环境主要有2个相带：一是台地内，尤其是半局限台地与开阔台地的转折处或台内缓坡上，如塘参1井、塔中23井上奥陶统的生物礁：另一个是台地边缘，如塔中45井-塔中44井-塔中24井-带为台缘外带，以发育中高能粒屑滩和骨架礁组合为特色，而大致在塔中35井-塔中12井-塔中15井-塔中161井-带为台缘内带，发育中低能粒屑滩、灰泥丘及障积礁组合．     

四川盆地北部长兴组生物礁地震响应特征与分布规律

井下钻探结果和地震资料表明四川盆地北部上二叠统长兴组生物礁发育,通过对典型井长兴组岩性与电性资料的分析,明确了生物礁的岩性与储层发育特征。根据井下生物礁及围岩岩性与电性资料并结合过井地震剖面反射波的几何特征,建立台地边缘生物礁的地震正演数值模型,通过对比生物礁模型地震正演记录与实际生物礁地震剖面,建立针对研究区台地边缘生物礁的地震响应特征模式。依据生物礁的地震响应特征对该地区连片二、三维地震测线开展地震相分析,通过已有钻井地震相与沉积相对应关系分析,指出了长兴组生物礁在该地区的分布规律。四川北部地区地震相与沉积相带具有良好的对应关系,存在环台棚-海盆相的台地前缘斜坡-台地边缘生物礁相-开阔台地相沉积体系,地震剖面上生物礁的外部形态呈丘状或透镜状,内部为杂乱反射特征;礁盖白云岩具有亮点反射特征,生物礁底界面出现上凸或者下凹反射现象,生物礁的上部地层具有披覆反射结构,四川盆地北部地区长兴组台地边缘生物礁相在台棚-海盆相东、西两侧沿北西向呈条带状展布,分布面积大于2000km~2,生物礁气藏勘探潜力巨大。     

生物礁油气藏近源成藏模式及其对勘探的启示

近源成藏(近地生成就地储集)是生物礁油气藏的主要成藏模式,生物礁可构成有利储集空间,其上下左右相邻地层的泥页岩或碳酸盐岩作为其优质烃源岩和盖层。根据烃源岩与礁的相对位置及其组合关系,可将生物礁近源成藏模式划分为单源生烃型和多源生烃型两大类,共6种类型。单源生烃型只含一套烃源岩,包括盖生型、侧生型和下生型3种类型;多源生烃型包含两套及两套以上烃源岩,目前只发现侧生-盖生型、侧生-顶生型和上下共生型3种类型。分析了烃源与储层配置关系对生物礁油气藏勘探的影响,认为只有礁体周围的地层具备良好的烃源条件和盖层条件时,才有利于生物礁的成藏,生物礁远源成藏是非常少见的。     

黔东北石阡志留纪最早期生物礁的形态学和古生态学

上扬子区志留纪早期的浅水相灰岩和壳相动物分布,多局限于滇黔桂古陆之北陆浅海近岸带。黔东北石阡兰多维列世埃隆期香树园组上部记录了华南板块奥陶纪末生物灭绝事件之后最早后生动物礁群落的复苏,持续相对长时间清澈浅水环境是造礁的基本条件,南陆北海的古地貌塑造了礁体各亚相的展布方式,礁灰岩南北延伸出露宽度约为150m,最大保存厚度约为20余米,形态学上呈现点礁特征。棘屑滩之上的珊瑚—层孔虫格架礁具有较高的生物多样性,属全球志留纪最常见的礁灰岩类型;南侧为礁后薄层棘屑滩堆积;礁核部位的大量珊瑚—层孔虫原地生长格架具有抗浪性,并障积不同粒度的壳相化石和内碎屑颗粒,有利于加速沉积形成块状礁灰岩和正向地貌;礁体北端为薄层生屑灰岩夹少量粉砂—泥质薄层的礁前沉积区;礁顶薄层灰岩中粉砂质—泥质成分逐渐取代珊瑚—层孔虫格架岩,相变为雷家屯组下部的陆源碎屑岩沉积,海水浑浊度增高是终止生物礁群落栖居的主控因素。     

南沙群岛永暑礁澙湖沉积的晚全新世风暴事件记录

位于南沙群岛永暑礁西南小澙湖的南永4井岩芯柱中含多层珊瑚枝和珊瑚砾石的堆积,反映了突发性风暴事件造成的珊瑚碎屑快速搬运和堆积。全新世晚期约4 000 aBP以来,澙湖珊瑚砾堆积记录了1 400870BC、660BC390AD、600770AD和940-1992AD 4个主要的风暴事件频发时期,并且风暴的强度呈阶段性增强。风暴事件还表现出千年和百年尺度的周期性波动,具有1 280 a、370 a、210230 a、140150 a和90 a的准周期,与全新世气候环境的周期性变化相对应,很大程度上受太阳活动周期变化的影响。     

Is proximity to land-based sources of coral stressors an appropriate measure of risk to coral reefs? An example from the Florida Reef Tract

Localized declines in coral condition are commonly linked to land-based sources of stressors that influence gradients of water quality, and the distance to sources of stressors is commonly used as a proxy for predicting the vulnerability and future status of reef resources. In this study, we evaluated explicitly whether proximity to shore and connections to coastal bays, two measures of potential land-based sources of disturbance, influence coral community and population structure, and the abundance, distribution, and condition of corals within patch reefs of the Florida Reef Tract. In the Florida Keys, long-term monitoring has documented significant differences in water quality along a cross-shelf gradient. Inshore habitats exhibit higher levels of nutrients (DIN and TP), TOC, turbidity, and light attenuation, and these levels decrease with increasing distance from shore and connections to tidal bays. In clear contrast to these patterns of water quality, corals on inshore patch reefs exhibited significantly higher coral cover, higher growth rates, and lower partial mortality rates than those documented in similar offshore habitats. Coral recruitment rates did not differ between inshore and offshore habitats. Corals on patch reefs closest to shore had well-spread population structures numerically dominated by intermediate to large colonies, while offshore populations showed narrower size-distributions that become increasingly positively skewed. Differences in size-structure of coral populations were attributed to faster growth and lower rates of partial mortality at inshore habitats. While the underlying causes for the favorable condition of inshore coral communities are not yet known, we hypothesize that the ability of corals to shift their trophic mode under adverse environmental conditions may be partly responsible for the observed patterns, as shown in other reef systems. This study, based on data collected from a uniform reef habitat type and coral species with diverse life-history and stress-response patterns from a heavily exploited reef system, showed that proximity to potential sources of stressors may not always prove an adequate proxy for assigning potential risks to reef health, and that hypothesized patterns of coral cover, population size-structure, growth, and mortality are not always directly related to water quality gradients.     

Future makers or future takers? A scenario analysis of climate change and the Great Barrier Reef

The extent to which nations and regions can actively shape the future or must passively respond to global forces is a topic of relevance to current discourses on climate change. In Australia, climate change has been identified as the greatest threat to the ecological resilience of the Great Barrier Reef, but is exacerbated by regional and local pressures. We undertook a scenario analysis to explore how two key uncertainties may influence these threats and their impact on the Great Barrier Reef and adjacent catchments in 2100: whether (1) global development and (2) Australian development is defined and pursued primarily in terms of economic growth or broader concepts of human well-being and environmental sustainability, and in turn, how climate change is managed and mitigated. We compared the implications of four scenarios for marine and terrestrial ecosystem services and human well-being. The results suggest that while regional actions can partially offset global inaction on climate change until about mid-century, there are probable threshold levels for marine ecosystems, beyond which the Great Barrier Reef will become a fundamentally different system by 2100 if climate change is not curtailed. Management that can respond to pressures at both global and regional scales will be needed to maintain the full range of ecosystem services. Modest improvements in human well-being appear possible even while ecosystem services decline, but only where regional management is strong. The future of the region depends largely on whether national and regional decision-makers choose to be active future ‘makers’ or passive future ‘takers’ in responding to global drivers of change. We conclude by discussing potential avenues for using these scenarios further with the Great Barrier Reef region's stakeholders.