Benthic Resources Research Articles

Unravelling Lessonia trabeculata management in coastal areas of the Atacama region of northern Chile through a DPSIR approach: Insights for sustainable plans

Subtidal Lessonia trabeculata is one of the primary kelp resources of northern Chile. It is an ecosystem engineer that provides habitat, shelter, and food for invertebrates and fish. This fishery has been developed by a collection of stranded algae carried out by legally registered fishers and illegal collectors in open-access areas and management and exploitation areas for benthic resources. Due to the current high demand on the international market, the collection of dead plants is supplemented by direct extraction. In response, a management plan has been implemented to regulate extraction efforts and institute annual quotas. The dynamics of the L. trabeculata fishery in the Atacama region over 20years were evaluated using the conceptual framework of the driver-pressure-state-impact-response (DPSIR) approach. The fishing dynamics are strongly conditioned by price fluctuations, promoting the growth of fishing efforts (pressure) in response to economic indicators (driving forces). This often leads to a high volume of extractions of resources (impact) reflected in the increase in extractors and landings in spite of the establishment of quotas (responses), that generate intense pressure on local populations of algae and other commercially important fish and invertebrates (state). A lack of knowledge was detected regarding population aspects and its associated communities. Consequently, this kelp has been mismanaged without a specific focus on this species. Finally, the indicators included in the present DPSIR analysis enable a global understanding of the L. trabeculata fishery, and it should be considered as a basis for future studies and the implementation of resource management strategies.

Characterizing energy flow in kelp forest food webs: a geochemical review and call for additional research

Kelp forests are highly productive coastal habitats that serve as biodiversity hotspots and provide valuable ecosystem services. Despite being one the largest marine biomes, kelp forests have been drastically understudied relative to other marine systems. Notably, while the role of kelp as habitat‐forming, or ‘foundation species', is well‐documented, a comprehensive understanding of kelp forest food web structure is lacking, particularly regarding the importance of kelp‐derived energy/nutrients to consumers. Here, we provide a biogeographic perspective on the energetic underpinning of kelp forests based on published literature. We targeted studies which used geochemical proxies – stable isotope analysis – to examine the transfer of carbon from kelp to local consumers. These studies (n = 94) were geographically skewed, with > 40% from Northern European Seas and Temperate Northeast Pacific. Quantitative estimates for the percentage of kelp energy (or kelp + macroalgae if sources were pooled) incorporated by local consumers came from 43 publications, which studied 141 species and 35 broader taxonomic groups. We examined these data for trends among functional groups and across upwelling regimes. No patterns are evident at present, perhaps due to the paucity or variability of available data. However, energetic subsides from kelps clearly support a wide range of diverse taxa around the globe. We also characterized biogeographic patterns in δ13C values of kelps and particulate organic matter (POM, a phytoplankton proxy), to evaluate potential limitations of stable isotope analysis in disentangling the relative contributions of pelagic versus benthic resources to coastal food webs. Globally, kelps and POM differed by > 4.5‰, but there was substantial variation among regions and kelp species. Accordingly, we discuss advances in stable isotope techniques which are facilitating more precise analysis of these complex energetic pathways. We end by proposing four main avenues of critical future research that will shed light on the resilience of these communities to global change.

A giant nektobenthic radiodont from the Burgess Shale and the significance of hurdiid carapace diversity.

Radiodonts, stem-group euarthropods that evolved during the Cambrian explosion, were among the largest and most diversified lower palaeozoic predators. These animals were widespread geographically, occupying a variety of ecological niches, from benthic foragers to nektonic suspension feeders and apex predators. Here, we describe the largest Cambrian hurdiid radiodont known so far, Titanokorys gainesi, gen. et sp. nov., from the Burgess Shale (Marble Canyon, Kootenay National Park, British Columbia). Estimated to reach half a metre in length, this new species bears a very large ovoid-shaped central carapace with distinct short posterolateral processes and an anterior spine. Geometric morphometric analyses highlight the high diversity of carapace shapes in hurdiids and show that Titanokorys bridges a morphological gap between forms with long and short carapaces. Carapace shape, however, is prone to homoplasy and shows no consistent relationship with trophic ecology, as demonstrated by new data, including a reappraisal of the poorly known Pahvantia. Despite distinct carapaces, Titanokorys shares similar rake-like appendages for sediment-sifting with Cambroraster, a smaller but much more abundant sympatric hurdiid from the Burgess Shale. The co-occurrence of these two species on the same bedding planes highlights potential competition for benthic resources and the high diversity of large predators sustained by Cambrian communities.

Integrating human and ecological dimensions: The importance of stakeholders' perceptions and participation on the performance of fisheries co-management in Chile.

Increasing attention is paid to the interdependence between the ecological and human dimensions to improve the management of natural resources. Understanding how artisanal fishers see and use the common-pool resources in a co-management system may hold the clue to establishing effective coastal fisheries policies or strengthening existing ones. A more comprehensive planning of the system will also have a bearing on how to reduce conflicts and strengthen social networks. We surveyed artisanal fishers and decision-makers to determine their perceptions about the Management and Exploitation Areas of Benthic Resources (known as MEABR) in Chile's Biobio region. We performed a field study from November 2018 to August 2019, applying a set of questionnaires to determine the ecological and human attributes that contribute to MEABR outcomes, and then constructed composite scores for those attributes according to a multidimensional scaling technique ("Rapfish"). We find that fishers have different perspectives: surprisingly, women highlighted that the institutional dimension was the most influential on MEABR performance, whereas men highlighted the ecological and economic outcomes. The decision-makers' role in the MEABR system was considered adequate, but communication and socialization of regulations were irregular. Results also showed that fishers expressed dissatisfaction with illegal fishing practices (poaching), productivity, profits, and conflicts inside and outside the MEABRs. Our study allowed us to better understand how the MEABR has developed in the region. We recommend strengthening local management strategies with particular attention paid to networking among stakeholders, including gender inclusive relationships.

Diversity of small-scale fisheries in Chile: Environmental patterns and biogeography can inform fisheries management

Small-scale fisheries are major contributors to global fishing catch and to the livelihoods of many coastal communities. However, little is known about these fisheries, the spatial heterogeneity in which they are found, and the factors that explain this heterogeneity. In Chile, the distinct environmental regimes driven by the Humboldt Current System can contribute to a high diversity in the species targeted by small-scale fisheries. Through a Chilean case-study, we aimed to characterize how environmental and socio-economic conditions influence small-scale benthic fisheries in 15 coves, straddling two biogeographic regions along 24 degrees of latitude (ca. 2600 km) and administered by a nation-wide management framework. We compiled and analyzed a long-term database generated by a standardized monitoring protocol in order to determine how fishing techniques, benthic resource diversity, effort and fishers’ income vary along the coastline. Our results highlighted that small-scale fisheries are strongly influenced by the variations in the environmental conditions, which determine variations in landings along the coast. Our analyses also illustrated how fishers seek to ensure their livelihoods by dealing with regional and local environmental conditions, ecology of marine resources, socio-economic context and a management system that is not able to accommodate fisheries’ heterogeneity. Our results suggest that future changes to the Chilean management system should integrate the spatial variation observed among small-scale fisheries to ensure sustainable livelihoods of the fishers and conservation of the marine resources. Fishery management rules should be shaped according to the region where they are applied, moving from homogeneous nation-wide systems, or systems adapted from administrative divisions to differentiated co-management systems based on biogeographic units.

Accounting for spatial dependence improves relative abundance estimates in a benthic marine species structured as a metapopulation

Sea urchin (Loxechinus albus) is one of the most important benthic resource in Chile. Due to their large-scale spatial metapopulation structure, sea urchin subpopulations are interconnected by larval dispersion, so the recovery of local abundance depends on the distance and hydrodynamic characteristics of their spatial domain. Currently, this resource is evaluated with classical stock assessment models, using standardized catch per unit effort (an index of relative abundance) as a key piece of information to determine catch quotas and achieve sustainability. However, these estimates assume hyperstability for the total population, ignoring spatial dependence among fishing sites, which is a fundamental concept for populations structured as metapopulation. We develop a Bayesian catch standardization model with explicit spatial dependence to better address the structure of this population. The proposed model performs statistically better compared to a model without spatial dependence, based on leave-one-out cross-validation, and predictive distributions also show that parameter estimation is consistent with the data. We argue that incorporating spatial structure improves the estimated relative abundance index in a population structured as a metapopulation. Our improved index of abundance will lead to better assessments and management advice, thus improving the sustainability of the stock.

Fatty acid accumulation in feeding types of a natural freshwater fish population

Fatty acids are widely used to study trophic interactions in food web assemblages. Generally, it is assumed that there is a very small modification of fatty acids from one trophic step to another, making them suitable as trophic biomarkers. However, recent literature provides evidence that many fishes possess genes encoding enzymes with a role in bioconversion, thus the capability for bioconversion might be more widespread than previously assumed. Nonetheless, empirical evidence for biosynthesis occurring in natural populations remains scarce. In this study, we investigated different feeding types of perch (Perca fluviatilis) that are specialized on specific resources with different levels of highly unsaturated fatty acids (HUFAs), and analyzed the change between HUFA proportions in perch muscle tissue compared to their resources. Perch showed matching levels to their resources for EPA, but ARA and especially DHA were accumulated. Compound-specific stable isotope analyses helped us to identify the origin of HUFA carbon. Our results suggest that perch obtain a substantial amount of DHA via bioconversion when feeding on DHA-poor benthic resources. Thus, our data indicate the capability of bioconversion of HUFAs in a natural freshwater fish population.

Abundance of a recently discovered Alaskan rhodolith bed in a shallow, seagrass-dominated lagoon

Abstract Rhodoliths are important foundation species of the benthic photic zone but are poorly known and rarely studied in Alaska. A bed of Lithothamnion soriferum rhodoliths was discovered in 2008 in Kinzarof Lagoon, Alaska, a shallow-water embayment dominated by eelgrass (Zostera marina). Rhodolith spatial extent and biomass were estimated to assess trends and environmental factors that may influence rhodolith distribution and abundance during four years spread over a 12-year period (2008–2010, and 2019). Presence and biomass of rhodoliths were negatively associated with percent eelgrass cover. Biomass of rhodoliths also decreased with increased water temperature. Rhodoliths occurred in two primary areas of the lagoon, a 182 ha core area in a shallow water (mean tide depth of −0.03 m MLLW) tidal channel with low eelgrass density, and a 22 ha outlying area at shallower water depths (>0.2 m MLLW) with moderate to high eelgrass cover. There was no apparent trend in rhodolith biomass over the study period despite wide variation in mean annual estimates. This study establishes a baseline for continued investigations and monitoring of this important benthic resource in Alaska.

The interplay of natural variability, productivity and management of the benthic ecosystem in the Humboldt Current System: Twenty years of assessment of Concholepas concholepas fishery under a TURF management system

Areas with controlled access, as Marine Protected Areas (MPAs) and Territorial Use Rights for Fisheries (TURF), are conceived as tools to contribute to the ecosystem conservation and fisheries sustainability. Management and Exploitation Areas for Benthic Resources (MEABR), a TURF system implemented in Chile, offers the opportunity to test this hypothesis. The management in these areas is based mainly on the assessment of the resources population status, with low or no consideration of the ecological - environmental effects that condition their productivity. In this study, we evaluate ecological trophic dynamics of the rocky subtidal community configuration in four periods along 20 years of the highly productive Choros Island MEABR – MPA, including one pre-implementation period. In this TURF, the carnivore gastropod Concholepas concholepas (locally known as “loco”) is the main targeted resource. The performance of ecosystem indexes of this TURF increased during the MEABR regime as compared with the pre MEABR implementation. Nevertheless, the most conspicuous increase occurred in 2013, primarily in response to changes in environmental conditions and their direct and indirect effects on community interactions. The analysis of interactions between guilds indicated that the main drivers were the interaction between the primary productivity, prey abundance and the top predator loco. This produces a long-term dynamic of the system modulated by the interplay of environmental variability, which at benthic community level increases prey populations thus sustaining increased loco productivity. In turn, intensified predation of loco reduces its prey. This produces natural productivity fluctuations, which counteract the expected outcome of management actions, impeding to achieve stable landings in the long term.

Trophic complexity of small fish in nearshore food webs

Small nearshore fishes are an important part of lacustrine and functional diversity and link pelagic and benthic habitats by serving as prey for larger nearshore and offshore fishes. However, the trophic complexity of these small nearshore fishes is often unrecognized and detailed studies of their role in food webs are lacking. Here, we examined niche space patterns of small nearshore fish species using Bayesian analyses of carbon and nitrogen stable isotope data in nine freshwater lakes that are among the largest lakes in Minnesota. We found considerable variability in niche areas within species and high variability in niche overlap across species. At the assemblage level, niche overlap (average diet overlap of all species pairs at a lake) decreased as whole-lake species richness increased, possibly indicating a greater degree of resource specialization in more speciose lakes. Overall fish niche space was weakly but significantly related to niche space of their invertebrate prey. Although nearshore benthic resources contributed to fish diets in all lakes, all fish species also had non-negligible and variable contributions from pelagic zooplankton. This inter- and intraspecific variability in trophic niche space likely contributes to the multi-level trophic complexity, functional diversity, and potentially food web resilience to ecosystem changes.

Spatio-temporal changes in the biochemical parameters of the fishery resource Concholepas concholepas (Gastropoda: Muricidae) in the Southeastern Pacific Ocean

The fishery resource Concholepas concholepas is a key species in the benthic marine ecosystems of the Southeastern Pacific Ocean. In the present study, the spatio-temporal changes in the biochemical parameters were evaluated for adult individuals of C. concholepas. They were sampled in summer and winter under upwelling and Non-upwelling conditions in two Management and Exploitation Areas for Benthic Resources of Valparaíso, Chile. The results indicated that the variation in the biochemical parameters is explained to a greater extent by the season. For example, in both upwelling and Non-upwelling conditions, we found a higher content of total lipids, proteins, glucose, and energy in winter than summer. Temporal variations can be explained by the reproductive process after summer season, in which the egg spawning require a greater energy reserves to be perform. Nonetheless, differences in the nutritional status of preys along seasons of the year, can also influence on these results. In fact, these variations in the biochemical parameters of C. concholepas may be indicative of an adaptive seasonal physiological response to the environment for maintaining an optimal energy budget year-round. Altogether, this knowledge will contribute to the Management and Exploitation Areas for Benthic Resources, improving regulatory measures during the annual period of captures and landings of C. concholepas, favoring a more sustainable fishery in the Southeastern Pacific Ocean within an ecosystem approach.

The use of fishers’ knowledge to assess benthic resource abundance across management regimes in Chilean artisanal fisheries

Globally, marine fisheries remain largely unassessed, particularly small-scale fisheries in developing countries. Fishers’ knowledge has proven to be valuable to help fill gaps of information in otherwise unassessed fisheries. This study tested the reliability of fishers’ knowledge to estimate the abundance of two benthic resources, locos (Concholepas concholepas) and keyhole limpets (Fissurella spp.), across two management regimes, territorial user rights for fisheries (TURF) and open access areas (OAA), over ~500 km of coastline in central Chile. Fishers’ knowledge (FK) was quantified using systematic interviews and compared to direct assessments (DA). Additionally, resource abundance was compared between the fishing regimes, considering regions with different concentration of TURFs (and consequently different availability of OAAs). The results show that abundances estimated by the two methods were highly consistent for the most valuable resource (the loco) and quite reliable for the keyhole limpet (for 67% of the comparisons). Abundances of both resources were higher in TURFs than in OAAs, a pattern detected by both FK and DA. The results clearly show the potential of this approach to be applied for the Chilean benthic fisheries over large scales. Interestingly, the results also show significantly lower abundance of locos in OAAs than in TURFs at coves immersed in zones with low availability of open access fishing grounds, suggesting the influence of effort displacement after the implementation of TURFs. This ancillary result highlights the need for seascape management plans that consider the potential, unintended effects of TURFs on resources beyond their boundaries. These findings are of both local and global interest, supporting the use of FK to inform management in unassessed small-scale fisheries.

Can a Territorial Use Right for Fisheries management make a difference for fishing communities?

Territorial use rights in fisheries (TURFs) is a model used worldwide, in which the management of resources is carried out jointly by the administration and the users. In Chile, a TURF system named Management and Exploitation Areas for Benthic Resources (MEABR) was established during the nineties. The principal goal of the MEABR is the conservation of benthic resources, aiming for the sustainability of benthic fishing. Two decades after its enactment, doubts persist regarding the economic impacts generated by this regime. The present work uses a quasi-experimental method to evaluate the socio-economic impacts of this TURF system. A total of 2722 artisanal-vessel owners, separated into two groups, members, and non-members of a MEABR, were evaluated. We use data from a ten-year span from the beginning of the actual implementation of the MEABR to assess its impact. Results show that being a member of a MEABR increases income by 20%, on average.

Co-Management of Small-Scale Fisheries in Chile From a Network Governance Perspective

We examine decision-making, shared authority, and pluralism as key characteristics for the effective co-management of natural resources. Drawing on the concept of network governance, we complement this approach by studying localized practices of governance that support existing and compensate for missing aspects in the regulation. The regime of territorial use rights for fisheries (TURF) in Chile is a recognized example of large-scale co-management that has given rise to local organizations that manage and exploit benthic resources. Based on multi-sited qualitative fieldwork across five regions, we analyze practices with respect to two governance objects: the deterrence of illegal fishing and the periodic assessment of the fisheries’ biology fields. Our analysis shows that local fisher organizations have institutionalized informal practices of surveillance and monitoring to fill in the gaps of existing regulations. Although fisher organizations and consultants—the so-called management and exploitation areas for benthic resources (AMERB)—have managed to operate the TURF regime, they depend on the government to enforce regulations and receive public subsidies to cover the costs of delegated governance tasks. We suggest that governance effectiveness could benefit from delegating additional authority to the local level. This would enhance the supervision of productive areas and better adaptation of national co-management regulations to the specific geographical context.

Competition between Invasive Ruffe (Gymnocephalus cernua) and Native Yellow Perch (Perca flavescens) in Experimental Mesocosms

Ruffe (Gymnocephalus cernua) were introduced to North America from Europe in the mid-1980s and based on similar diets and habit use may compete with yellow perch (Perca flavescens). To examine competitive interactions between invasive ruffe and native yellow perch, individually marked perch and ruffe were placed in mesocosms in a small lake. Mesocosms allowed fish to interact and feed on the natural prey populations enclosed. In the first experiment, four treatments were assessed: 28 perch, 14 perch + 14 ruffe, 14 perch, and 7 perch + 7 ruffe. Yellow perch growth was significantly lower in the presence of ruffe (ANOVA, p = 0.005) than in treatments containing only perch. In a second experiment, an increasing density of one species was superimposed upon a constant density of the other in parallel treatment series. Growth rates of both ruffe and perch declined when ruffe density was increased (t test, p = 0.006). However, neither ruffe nor perch growth was affected by increasing perch density. Total stomach content mass of perch was significantly decreased by ruffe in both years (p < 0.02), but no effects of ruffe on the composition of perch diets were observed. Ruffe growth and food consumption was greater than that of perch for both experiments. Ruffe can outcompete yellow perch when both species depend on a limited benthic food resource. Thus there is reason for concern for the ecological effects of ruffe if they expand their range into Lake Erie or North American inland lakes that contain yellow perch.

Cooperación, cohesión y volubilidad institucional en los sistemas organizacionales de la pesca artesanal chilena

En los últimos años, diversas investigaciones han aportado a entender cómo las instituciones, las reglas formales e informales, en contextos de recursos comunes, influyen en las decisiones y resultados de los agentes que componen los entramados institucionales. El propósito de este artículo es 1) describir etnográficamente un sistema institucional situado en la pesca artesanal chilena. El análisis se centra en las estrategias de múltiples agentes en torno a la administración de un Área de Manejo de Recursos Bentónicos (AMERB), adjudicada por un sindicato de pescadores de la Caleta Coquimbo y 2) dilucidar cómo los incentivos de estos sistemas prescriben problemas relativos a la volubilidad de las organizaciones que deberían velar por la sustentabilidad ecológica para estas pesquerías tradicionales. Los resultados de la investigación muestran, además, la sinergia entre metodologías eminentemente cualitativas como la etnografía y la confección de modelos matemáticos explicativos como los de la Teoría de Juegos.

Fatty acids reveal salmonine – prey relationships in Lake Michigan

Lake Michigan salmon and trout populations are important species for recreational fisheries and food web management, and are largely supported through stocking efforts, with varying degrees of natural recruitment. Ongoing fisheries management of these salmonine populations is dictated by relationships between predator and prey abundance as well as community structure within the lake. However, while prey fish biomass has declined, and species composition has changed in recent decades, knowledge of prey consumption by the salmonine community has lagged. Herein, we explore trophic relationships using fatty acids profiles, which offer insights into the foraging habits and energy pathways relied on over weeks to months prior to collection. Fatty acids of the prey base for salmonines in Lake Michigan indicate a gradient of foraging habits that range from pelagic (typified by alewife and rainbow smelt) versus benthic (i.e., slimy sculpin and round goby) resource use. Fatty acids implied that there was more variation in foraging habits among individual lake trout and brown trout compared to Chinook salmon, coho salmon and rainbow trout, which appeared to all rely almost exclusively on pelagic prey. Fatty acid profiles also indicated size-based shifts in foraging habits; for example, larger lake trout consuming a greater proportion of benthic prey than smaller individuals. Data herein suggest that Chinook and coho salmon, as well as rainbow trout, are more likely to experience competitive interactions during times of low pelagic prey-fish abundance in Lake Michigan, whereas brown and lake trout are able to utilize benthic resources to a greater degree.

Maturity Assessment for the Implementation of the First Fishery Regulation in Patagonian Marine Gastropods

Fil: Cumplido Esmoris, Mariano Jose. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Centro Nacional Patagonico. Instituto de Biologia de Organismos Marinos; Argentina

Sustainability of the Artisanal Fishery in Northern Chile: A Case Study of Caleta Pisagua

The Humboldt Current, one of the most productive waters in the world, flows along the Chilean coast with high primary production level. However, living marine resources in these waters are declining due to overexploitation and other anthropogenic and environmental factors. It has been reported that deploying artificial reefs in coastal waters can improve the production of benthic resources. To ensure the sustainability of coastal fisheries in northern Chile this study aims to investigate fishermen’s perceptions on deploying artificial reefs and propose future management measures using Caleta Pisagua as a case study. Interviews of artisanal fishermen regarding four aspects: fishermen profile, fishing activity, resources, and artificial reefs were conducted. Results showed that most fishermen favored the implementation of artificial reefs within the Areas of Management and Exploitation of Benthic Resources (AMERBs). In addition, deploying artificial reefs appears to be socio-economically necessary for the artisanal fishermen whose livelihood is being affected by the overexploitation of coastal fish and because hard substrates essential for benthic resources are in short supply within this administration area. It is recommended that criteria for the deployment of artificial reefs as well as specific management plans for main and secondary species should be developed.

Social-ecological vulnerability to climate change in small-scale fisheries managed under spatial property rights systems

Small-scale fisheries (SSFs), which provide an important source of livelihood for many coastal communities, are at risk from climate change. Benthic organisms are likely to be particularly affected by the impacts of climate change due to their low spatial mobility, which limits their capacity for adaptation. Therefore, SSFs that target sedentary resources (“S-fisheries”) will potentially be among the most impacted types of fishery. The pathways of such impacts can be studied in an integrated approach by means of social-ecological vulnerability assessment. The stalked barnacle (Pollicipes pollicipes) fishery, one of the most important S-fisheries in Galicia (NW Spain), represents a complex social-ecological system rooted within the culture of the region. Along Galician coast, this benthic resource is co-managed by the territorial use rights in fisheries (TURFs) scheme. The vulnerability assessment involves ranking TURF systems according to the exposure of the resource to climate hazards, the sensitivity of dependent people and the capacity of the system to adapt to the impacts. After analyzing 26 stalked barnacle TURFs (79% of all Galician TURFs), we identified the most vulnerable zones (Muxía and O Pindo), as indicated by high levels of ecological vulnerability and social sensitivity and low adaptive capacity. We discuss different ways of increasing the adaptive capacity of TURFs based on local knowledge and literature reviews. Vulnerability assessment represents a powerful tool that can be used to help policy-makers develop adaptation strategies needed at different time scales, ultimately contributing towards better informed, sustainable and efficient fisheries management.