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Abstract  This review is based on 58 climate-fisheries models published over the last 28 years that describe the impacts of fishery pressure and environmental variability on populations and ecosystems and include basic principles of population dynamics. It points out that the incorporation of environmental factors in fishery models has already been done and is of great importance for future models used in the assessment of marine resources. The work is guided by the questions to what extent have these models a) enhanced our understanding of the interrelationships between the environment, the fishery and the state of the exploited resources and b) helped to improve the prediction of population dynamics and the assessment of marine resources. For each of the six most commonly used model categories a case study is critically analyzed. The problems of “breaking relationships” between environmental factors and the biological response used in models, the trade-off between model complexity (realism) and simplicity (data availability) and the potential of multivariate climate indices for forecasting ecosystem states and for use as proxies for combined models are discussed, as are novel non-linear and spatially explicit modeling approaches. Approaches differ in terms of model complexity, use of linear or non-linear equations, number of parameters, forecast time horizon and type of resource modelled. A majority of the models were constructed for fish and invertebrate stocks of the northeast Pacific and the epicontinental seas of the Atlantic, reflecting the advancement of fisheries science in these regions. New, in parts highly complex models and sophisticated approaches were identified. The reviewed studies demonstrate that the performance of fished stocks can better be described if environmental or climatic variability is incorporated into the fisheries models. We conclude that due to the already available knowledge, the greatly enhanced computer power, new methods and recent findings of large-scale climatic/oceanographic cycles, fisheries modeling should progress greatly in the coming years. [ABSTRACT FROM AUTHOR]

Abstract  Philippines coastal fisheries research started during the colonization period in the 1800s with the basic taxonomic identification of the countries aquatic resources and a description of their distribution in national waters. Research further evolved with the change from localized fisheries governance to a centralized one, presently, with a combination of both. The dramatic postwar expansion of Philippine fisheries in the mid 1940s led to the need for sustainable resources management. In the mid-1970s, single-species fisheries approaches (i.e. specifically surplus production models) indicated the overfished state of the Philippine coastal fisheries resources. These early models together with additional ecological and socioeconomic studies, served as inputs to coastal resources management initiatives, in the context of an ecosystem approach. The implementation of further management schemes such as marine reserves and fish sanctuaries also resulted from these initiatives. The decentralization of governance of coastal resources in the 1990s led to participatory or co-management approaches for the local governance of coastal resources. The development and great improvement of ecosystem-based models in fisheries science (such as Ecopath with Ecosim [EwE]) during this period allowed for investigations into the interactions of the multispecies and multigear fisheries dynamics. Complementary models derived from single-species such as Yield per Recruit and Surplus production in conjunction with ecosystem-based (EwE-type) approaches are both needed in Philippine fisheries research. An emerging framework for sustainable Philippine fisheries management system requires mainstreaming of coastal governance with science based adaptive management for Philippine aquatic resources governance. [ABSTRACT FROM AUTHOR]

Vector symbolic architectures (VSA) are a viable approach for the hyperdimensional representation of symbolic data, such as documents, syntactic structures, or semantic frames. We present a rigorous mathematical framework for the representation of phrase structure trees and parse trees of context-free grammars (CFG) in Fock space, i.e. infinite-dimensional Hilbert space as being used in quantum field theory. We define a novel normal form for CFG by means of term algebras. Using a recently developed software toolbox, called FockBox, we construct Fock space representations for the trees built up by a CFG left-corner (LC) parser. We prove a universal representation theorem for CFG term algebras in Fock space and illustrate our findings through a low-dimensional principal component projection of the LC parser state. Our approach could leverage the development of VSA for explainable artificial intelligence (XAI) by means of hyperdimensional deep neural computation. [ABSTRACT FROM AUTHOR]

The editors would like to thank the following reviewers for their assistance. [Extracted from the article]

The article discusses various topics published within the issue including one by Erwin Riyanto Ardle and Matthias Wolff on the land use and land cover changes in the Segara Anakan lagoon in Java, Indonesia from 1987-2006, one by Peter Holtermann and colleagues on the hydrodynamics of the lagoon, and one by Saskia Hinrichs on the status, diversity and distribution patterns of mangrove vegetation in the lagoon.

Introduction: Mechanical failure due to dislocation, fracture and acetabular wear is a major complication associated with the use of spacers in the management of periprosthetic joint infection (PJI). We have developed a novel custom-made spacer in the setting of two-stage septic revision hip arthroplasty and present the preliminary results of our technique.Materials and Methods: Between May 2015 and November 2017, 30 patients underwent hip revision using the ENDO spacer technique in the setting of a two-stage septic exchange arthroplasty. The technique involves the dual mobility liner and the downsized stainless cemented straight stem in combination with antibiotic-loaded PMMA bone cement. The primary outcome measure was the overall spacer complication rate, particularly spacer dislocation. Furthermore, functional outcome using the Harris Hip Score (HHS) before spacer implantation and prior re-implantation was evaluated.Results: The mean age of the patients was 69.8 years (range from 45 to 85; SD = 9.9 years). No microorganisms were preoperatively found in 23 (76.7%) cases. Successful re-implantation was performed in all patients after a mean spacer duration time of 53.6 days (range 14-288 days; SD = 48.2). Spacer-related complications occurred in only two patients (6.7%). The HHS significantly improved from 34.0 (range 3-62; SD = 15.1) to 48.1 (range 11-73; SD = 15.7) (p = 0.0008).Conclusions: The ENDO spacer surgical technique is a feasible option in the treatment of periprosthetic joint infection (PJI), with a low dislocation rate. Furthermore, it allows early mobilization with the possibility of full-weight bearing. [ABSTRACT FROM AUTHOR]

Length-based methods are the cornerstone of many population studies and stock assessments. This study tested two widely used methods: the Powell-Wetherall (P-W) plot and the Lmax approach (i.e., estimating L∞ directly from Lmax). In most simulations, P-W estimates of the ratio total mortality/growth (Z/K ratio) were biased beyond acceptable limits (bias > 30%). Bias in Z/K showed a complex behavior, without possible corrections. Estimates of asymptotic length (L∞) were less biased than Z/K, but were very sensitive to intra-cohort variability in growth and to changes in the occurrence of large individuals in the sample. Exclusion of the largest size classes during the regression procedure or weighing by abundance does not solve these issues. Perfect linearization of the data and extremely narrow confidence intervals for Z/K will lead users to erroneous overconfidence in outputs. Clearly, the P-W method is not suitable for the assessment of Z/K ratios of natural populations. Estimation of L∞ may be tentatively possible under very specific conditions, with necessary external verifications. Also, this study demonstrates that there is no way to estimate L∞ directly from Lmax, since there is no particular relationship to expect a priori between L∞ and Lmax. Errors in estimating L∞ directly affect the estimate of the growth constant K and all other subsequent calculations in population studies, stock assessments and ecosystem models. New approaches are urgently needed for length-based studies of body growth (e.g., unconstrained curve fit with subsequent bootstrapping), that consider the inherent uncertainty regarding the underlying data and processes. [ABSTRACT FROM AUTHOR]

The structurally most developed Neotropical mangrove forests are found along the southern and central macrotidal Colombian Pacific coast. This extremely rainy area (>7,000 mm year) is sparsely populated and sustains a relatively small artisanal fishery. In this article, we present an ecosystem (trophic) model, built using Ecopath with Ecosim, containing 18 functional groups of a representative mangrove area of this coast. Similar to other mangrove ecosystem models, mangroves contribute most (96%) to total system biomass, providing the primary food source for other important compartments (e.g., crabs). However, most of the mangrove litterfall is constantly washed away by tidal currents, a possible reason for the very low mean transfer efficiencies to higher trophic levels and low biomass of epifauna and nekton found, compared with other Neotropical mangroves. Fish biomass is dominated by zoobenthivores (snappers, catfishes) and detritivores (mullets) which represent, together with mangrove cockles, the target resources of a low trophic level-based fishery. Very low salinities throughout the year may contribute to an impoverished community of primary and secondary consumers that is able to withstand but not flourish under these conditions. This mangrove ecosystem may be highly vulnerable to overexploitation according to the low energy reserve (overhead) of the system. [ABSTRACT FROM AUTHOR]

Bivalve aquaculture has become increasingly important for marine protein production and is an alternative to exploiting natural resources. Its further and sustainable development should follow an ecosystem approach, to maintain both biodiversity and ecosystem functioning. The identification of critical thresholds to development remains difficult. The present work aims at combining the calculation of the system's ecological carrying capacity (ECC) with the ecosystem view of resilience for a bay system exposed to bivalve (scallop) aquaculture. Using a trophic food-web model, a stepwise further expansion of culture activities was simulated, and the impact on the system was evaluated twofold: First, a recently developed approach to estimating ECC was used, and second, a resilience indicator was calculated, which is based on the distribution of consumption flows within the trophic network (sensu Arreguín-Sanchez in Ecol Model 272: 27-276, 2014). Results suggest that a culture expansion beyond present-day scale would (a) cause a shift in community composition towards a system dominated by secondary consumers, (b) lead to the loss of system compartments, affecting ecosystem functioning, and (c) result in a decrease in resilience, emphasizing the need to regulate aquaculture activities. The applicability and potential of this presented method in the context of an ecosystem-based approach to aquaculture is discussed. This work aims at adding to the ongoing discussion on sustainable bivalve aquaculture and is expected to help guide aquaculture management. [ABSTRACT FROM AUTHOR]

We evaluated the statistical models that best describe the selectivity of common fishing gears used in Lake Koka for four freshwater species widely distributed in Ethiopia and elsewhere: tilapia Oreochromis niloticus (L.), catfish Clarias gariepinus (B.), common carp Cyprinus carpio (L.), and barb Labeobarbus intermedius (R.). Sampling was conducted from October 2012 to March 2013 using gillnets (60, 80, 100, and 120 mm stretched mesh), longlines (4/0, 6/0, and 8/0 hooks size), and a beach seine with covered codend. Size at maturity ( L) was determined for each species. The SELECT method was used to explore unimodal selectivity models for gillnet and longline gears, while the logistic function was used for beach seine. Results show that a log-normal model best described gillnet selectivity for all species, while a normal scale model best described longline selectivity for C. gariepinus. Gillnets with ≥100 mm mesh and longlines with >4/0 hooks could be safely used, as they allow target resources to attain L before becoming vulnerable to fishing. The mesh size of the beach seine needs to be enlarged, as the estimated length of capture was much smaller than all L values. The results have important management implications for protecting juveniles and mega-spawners of the studied species in Lake Koka and beyond. [ABSTRACT FROM AUTHOR]

The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in the Indo-West-Pacific. It has a complex life cycle with a dispersing larvae phase, and benthic juveniles and adults. The former are stenohaline depending on high-salinity conditions to survive, whereas the latter are physiologically well adapted to changing temperatures and salinities, conditions that typically occur in mangrove habitats. Movement and habitat use of large juveniles and adults are well studied, and these life stages are known to utilize and move between various habitats within the mangrove ecosystem: intertidal flats as well as subtidal channels and flats. Females undertake long movements from brackish inshore waters to waters with oceanic conditions for spawning. Sensory abilities-of early stages and adult stages-have hardly been studied, and little is known about larval and early benthic stages in the wild. Summarizing, the literature revealed substantial gaps in the understanding of the spatiotemporal dynamics of the different life stages and of the clues that trigger recruitment, movement, and other behavior. This is the first comprehensive review on the life history, movement patterns, habitat use, and systemic role of S. serrata with emphasis on the respective life stages and geographic differences. We emphasize the need for further research into these processes as a basis for the sustainable management and conservation of this species. [ABSTRACT FROM AUTHOR]

Tropical coastal habitats like marshes, mangroves, and submerged grasses comprise diverse plant and animal communities and a certain degree of connectivity with other ecosystems. We compared the food web structure of a fringing mangrove-seagrass habitat and three fluvio-lagoons with marsh-eelgrass and mangrove-bare sediments during a dry season in Terminos Lagoon and Centla Wetlands, Southern Gulf of Mexico. Analysis of δC and δN stable isotopes in tissues of aquatic consumers, primary producers, and other carbon sources, in combination with isotope-based Bayesian methods, were performed to determine the main food sources and the isotopic niche of the consumers' communities. Consumers in the mangrove-seagrass site showed high dependence on phytoplankton (average contribution 31 %), macroalgae (20 %) and organic matter derived from seagrasses (17 %). In the fluvio-lagoons, consumers showed high dependence on marginal vegetation (16-46 %). Phytoplankton and mangrove epiphytes comprised other important resources at these sites (with contributions of 24-44 %). The isotopic niche of consumers from the fringing mangrove-seagrass site did not overlap with those from the fluvio-lagoons. Moreover, despite the predominance of generalist consumers in all sites, differences in their isotopic niche area were observed, with consumers from the marsh-eelgrass site showing the narrowest. This suggests that consumer resource availability greatly differs in these habitats. Our results provide valuable information that help increase our understanding about the trophic structure in these important estuarine systems. [ABSTRACT FROM AUTHOR]

Purpose: AIO KRK-0104 investigated first-line therapy of metastatic colorectal cancer (mCRC) with cetuximab, capecitabine and irinotecan versus cetuximab, capecitabine and oxaliplatin. This analysis investigated the impact of primary tumor location on outcome of patients. Patients and methods: Left-sided primary tumors were defined as tumors from rectum to left flexure, while tumors in the remaining colon were regarded right sided. Overall survival (OS), progression-free survival (PFS) and response rate were correlated with primary tumor location. A Cox regression model was used to evaluate interaction between primary tumor location and KRAS mutation. Results: Of 146 patients of the AIO KRK-0104 trial, 100 patients presented left-sided (of those 68 KRAS codon 12/13 wild-type) and 46 patients right-sided primary tumors (of those 27 KRAS codon 12/13 wild-type). Left-sided tumors were associated with significantly longer OS ( p = 0.016, HR = 0.63) and PFS ( p = 0.02, HR = 0.67) as compared to right-sided tumors. These effects were present in the KRAS codon 12/13 wild-type population (HR OS: 0.42; HR PFS: 0.54), while no impact of primary tumor location was evident in patients with KRAS codon 12/13 mutant tumors (HR OS: 1.3; HR PFS: 1.01). A significant interaction of KRAS status and primary tumor location concerning OS and PFS was observed. Conclusion: Our findings suggest that primary tumor location and KRAS codon 12/13 mutational status interact on the outcome of patients with mCRC receiving cetuximab-based first-line therapy. Left-sided primary tumor location might be a predictor of cetuximab efficacy. [ABSTRACT FROM AUTHOR]

Movements and habitat preferences of sharks relative to a central location are widely documented for many species; however, the reasons for such behaviors are currently unknown. Do movements vary spatially or temporally or between individuals? Do sharks have seasonal habitat and environmental preferences or simply perform movements at random at any time of the year? To help understand requirements for the designation of critical habitats for an endangered top predator and to develop zoning and management plans for key habitats, we examined vertical and horizontal movements, and determined habitat and environmental preferences of scalloped hammerhead sharks ( Sphyrna lewini). We tracked seven hammerheads for 19-96 h at Wolf Island (1.38ºN, 91.82ºW) between 2007 and 2009 using ultrasonic transmitters with depth and temperature sensors, and we profiled temperature through the water column. Movements of individual hammerheads fell in two classes: constrained (remaining near the island) and dispersive (moving offshore to pelagic environments). The central activity space or kernel off the southeast side of Wolf Island was small and common to most, but the area varied among individuals (mean ± SE 0.25 ± 0.2 km), not exceeding 0.6 km for any of the sharks, and not changing significantly between seasons. In general, hammerheads showed preference for the up-current habitat on the eastern side of Wolf Island in both the warm and cold seasons. However, the depth of sharks varied with season, apparently in response to seasonal changes in the vertical structure of temperature. Hammerheads performed frequent vertical excursions above the thermocline during offshore movements and, in general, were observed to prefer temperatures of 23-26 °C found above the thermocline. At times, though individuals moved into the thermocline and made brief dives below it. Our results provided evidence that hammerheads (1) are highly selective of location (i.e., habitat on up-current side of island) and depth (i.e., top of the thermocline) while refuging, where they may carry out essential activities such as cleaning and thermoregulation, and (2) perform exploratory vertical movements by diving the width of the mixed layer and occasionally diving below the thermocline while moving offshore, most likely for foraging. [ABSTRACT FROM AUTHOR]

Background:Liver-limited disease (LLD) denotes a specific subgroup of metastatic colorectal cancer (mCRC) patients.Patients and Methods:A total of 479 patients with unresectable mCRC from an irinotecan-based randomised phase III trial were evaluated. Patients with LLD and non-LLD and hepatic resection were differentiated. Based on baseline patient characteristic, prognostic factors for hepatic resection were evaluated. Furthermore, prognostic factors for median overall survival (OS) were estimated via Cox regression in LLD patients.Results:Secondary liver resection was performed in 38 out of 479 patients (resection rate: 7.9%). Prognostic factors for hepatic resection were LLD, lactate dehydrogenase (LDH), node-negative primary, alkaline phosphatase (AP) and Karnofsky performance status (PS). Median OS was significantly increased after hepatic resection (48 months), whereas OS in LLD (17 months) and non-LLD (19 months) was comparable in non-resected patients. With the inapplicability of Koehne's risk classification in LLD patients, a new score based on only the independent prognostic factors LDH and white blood cell (WBC) provided markedly improved information on the outcome.Conclusion:Patients undergoing hepatic resection showed favourable long-term survival, whereas non-resected LLD patients and non-LLD patients did not differ with regard to progression-free survival and OS. The LDH levels and WBC count were confirmed as prognostic factors and provide a useful and simple score for OS-related risk stratification also in LLD. [ABSTRACT FROM AUTHOR]

As tools within ecosystem-based fisheries management (EBFM), a wide range of Ecosystem Models (EMs) have been designed to represent ecosystem complexity, but it is not always clear how the outputs of these models can be applied. We address this debate in a literature review to illustrate how a better understanding of ecosystem modeling within the EBFM framework could facilitate the use of EMs in the decision-making process. We classify EMs according to their complexity, and qualitatively evaluate their level of success with regard to five general goals of EBFM. In principle, no single EM is found to successfully accomplish all the EBFM goals. Therefore, we suggest that the way in which ecosystem modeling can effectively contribute to EBFM is through a structured modeling process, which should be pursued according to the context of each specific area. Within this planning strategy a range of Ems should be considered, from rather simple ones with few parameters, whose outputs are scientifically robust but possibly of limited use within the EBFM, to those which include a large number of ecosystem elements yet at the expense of increased uncertainty. If multiple EMs, despite their different assumptions, leads to consistent and converging results then robust management decisions will be supported. The present paper appears particularly useful to anyone confronted with the selection of modeling tools for the implementation of fisheries management strategies considering the particular situation of the fishery. [ABSTRACT FROM AUTHOR]

Background: The AIO KRK-0104 randomised phase II trial investigated the efficacy and safety of two capecitabine-based regimens: combination of capecitabine and irinotecan (CAPIRI) plus cetuximab (CAPIRI-C) and combination of capecitabine with oxaliplatin (CAPOX) plus cetuximab (CAPOX-C) in the first-line treatment of metastatic colorectal cancer (mCRC). Treatment-related skin toxicity (ST) was evaluated separately for capecitabine and cetuximab. The present analysis investigates the correlation of capecitabine-attributed ST (Cape-ST) and parameters of treatment efficacy.Methods: Patients with mCRC were randomised to cetuximab (400 mg m(-2), day 1, followed by 250 mg m(-2) weekly) plus CAPIRI (irinotecan 200 mg m(-2), day 1; capecitabine 800 mg m(-2), twice daily, days 1-14, every 3 weeks), or cetuximab plus CAPOX (oxaliplatin 130 mg m(-2), day 1; capecitabine 1000 mg m(-2), twice daily, days 1-14, every 3 weeks).Results: Of 185 recruited patients, 149 (CAPIRI-C, n=78; CAPOX-C, n=71) received study treatment beyond the first tumour assessment and were evaluable for efficacy. Capecitabine-attributed ST, predominantly hand-foot syndrome, was observed in 32.2% of patients. Capecitabine-attributed ST grade 1-3 was associated with a significantly higher disease control rate (DCR) (97.9 vs 86.1%, P=0.038) compared with grade 0 toxicity. Moreover, Cape-ST grade 1-3 related to a markedly longer progression-free survival (PFS) (9.9 vs 5.6 months, P<0.001) and overall survival (OS) (32.8 vs 22.4 months, P=0.008). Separate analyses of treatment arms indicated that the effect of Cape-ST on PFS remained significant for both arms, whereas the effect on OS remained apparent as a strong trend.Conclusion: This analysis supports the hypothesis that for the evaluated regimens, a correlation exists between Cape-ST and treatment efficacy regarding DCR, PFS, and OS. [ABSTRACT FROM AUTHOR]

This study quantifies and spatially characterizes land use and land cover changes in the Segara Anakan lagoon (SAL), Java, Indonesia, from 1987–2006. Classification of four satellite (SPOT) images from the years 1987, 1995, 2004 and 2006 and field ground truth data from 2004 and 2005 were used for map generation. The results show major changes in the western area of the SAL, with large area increases of rice fields, dry land agriculture, aquaculture and rural areas, and decreases in mangrove cover, mud flat and lagoon area. In the eastern area, minor decreases in mangrove area and increase in aquaculture, rural and industrial areas were also observed. Changes are due to the filling of the lagoon with riverine sediments derived from the hinterland and to mangrove conversion and resources exploitation. The results of this study provide basic information which is required for developing measures towards a sustainable management and conservation of the SAL. [ABSTRACT FROM AUTHOR]

Peru experiences recurrent ENSO (El Niño Southern Oscillation) events during which the Peruvian bay scallop ( Argopecten purpuratus) undergoes substantial changes in its stock size. In the North of the country strong warm ENSO events are synonymous with floods and river discharges that negatively affect scallop biomass, while in the South increased sea surface temperatures lead to an increase in stock size. This paper explores how formal institutions respond to climate variability and resource fluctuations in the scallop fishery, and what role they play in the maintenance or erosion of resilience. The research shows that formal institutions are slow to learn, self-reorganize and respond to climate variability while fishermen’s responses are spontaneous, ensuring a rapid process of individual adaptation. Institutional responses are mostly ex-post, and are not strongly shaped by past experience, thus eroding the resilience of the system. However, fishermen’s responses sometimes lead to negative outcomes such as local stock overexploitation or ‘invasion’ of natural scallop habitats for scallop grow-out, and formal institutions play an important role in resilience building through the control of effort and entry in the fishery. In this paper causal loop diagrams are used to conceptualize the fishery system to highlight key variables and processes. The study thus provides the opportunity to explore the usefulness of causal loop diagrams and conceptual models combined with participatory approaches in the exploration of the resilience of a system. The case study also illustrates that individual adaptation, a feature of resilience, is occurring and will occur spontaneously, changing property right regimes and responding not only to climate variability but also market forces. In order to maintain and build resilience and engender positive management outcomes, formal institutions not only need to shape fishermen decision-making, they must also contribute to knowledge building as well as the adoption of innovative approaches. [ABSTRACT FROM AUTHOR]

The capacity to withstand perturbations and the propagation of direct and indirect effects of harvesting were explored in seagrass and sand–gravel subtidal subsystems of northern Chile using Ecopath II, Ecosim and Loop Analysis theoretical frameworks. The relative Ascendancy and Redundancy from Ecopath II and Ecosim models and the holistic stability measure ( F n ) given by Loop Analysis, all suggest that the sand–gravel subsystem is the more resistant and its fishery more sustainable. This outcome is relevant since the theoretical frameworks used are based on different assumptions but arrive at similar conclusions. If the fishery is included in the qualitative ecological models, which were found locally stable only when the fishery is self-controlled. While this conclusion is not new, its relevance here is that it emerges from qualitative multispecies modelling (Loop Analysis). Based on our model predictions, the biomass removal of the sea star Meyenaster gelatinosus would increase the standing stock of the commercial scallop Argopecten purpuratus only in the seagrass habitat, whereas the same man-made intervention may have an opposite effect in the sand–gravel habitat. We recommend to enunciate holistic models based on the theoretical framework used in the current work, which explore the reality from different perspectives assuming different givens. Based on these holistic explorations alternative and complementary management scenarios could be designed. [ABSTRACT FROM AUTHOR]

Food preferences, consumption rates and dietary assimilation related to food quality were investigated for the large semi-terrestrial and litter-consuming mangrove crab Ucides cordatus cordatus (Ocypodidae, L. 1763) in northern Brazil. Stomach contents were composed of mangrove leaves (61.2%), unidentified plant material and detritus (28.0%), roots (4.9%), sediment (3.3%), bark (2.5%), and animal material (0.1%). U. cordatus prefers Rhizophora mangle over Avicennia germinans leaves despite a higher nitrogen content, lower carbon to nitrogen (C/N) ratio and lower tannin content of the latter. Also, assimilation rates for senescent R. mangle leaves (C: 79.3%, N: 45.4%) were higher than for A. germinans leaves (C: 40.6%, N: 9.1%). Faeces composition indicates that A. germinans leaves were more difficult to masticate and digest mechanically. The leaf-ageing hypothesis, according to which crabs let leaves age in burrows to gain a more palatable and nutritive food, was rejected for U. cordatus since N content, C/N ratio and the abundance of microorganisms did not differ significantly between senescent leaves and leaves taken from burrows. The low microbial biomass on leaf surfaces and in the sediment indicates its minor importance for the nutrition of U. cordatus. It is concluded that high ingestion and assimilation rates of a R. mangle diet together with the consumption of algae allow for a high intake of C, N, and energy. The data suggest that the digestibility of mangrove leaves by U. cordatus is not hampered by tannins. This may have provided a competitive advantage over other leaf-consuming invertebrates unable to digest mangrove litter with high tannin concentrations. Due to the large stock biomass of U. cordatus in the study area, a great amount of finely fragmented faeces is produced (about 7.1 ton dry matter ha−1 year−1 in a R. mangle forest) which is enriched in C, N and bacterial biomass compared to the sediment. The decomposition of mangrove litter, and thus nutrient and energy transfer into the sediment, is greatly enhanced due to litter processing by U. cordatus. [ABSTRACT FROM AUTHOR]