Loxechinus Albus Research Articles

How ocean warming and acidification affect the life cycle of six worldwide commercialised sea urchin species: A review

AbstractOngoing global changes are expected to affect the worldwide production of many fisheries and aquaculture systems. Because invertebrates represent a relevant industry, it is crucial to anticipate challenges that are resulting from the current environmental alterations. In this review, we rely on the estimated physiological limits of six commercialised species of sea urchins (Loxechinus albus, Mesocentrotus franciscanus, Paracentrotus lividus, Strongylocentrotus droebachiensis, Strongylocentrotus intermedius and Strongylocentrotus purpuratus) to define the vulnerability (or resilience) of their populations facing ocean warming and acidification (OW&A). Considering that coastal systems do not change uniformly and that the populations’ response to stressors varies depending on their origin, we investigate the effects of OW&A by including studies that estimate future environmental mutations within their distribution areas. Cross‐referencing 79 studies, we find that several sea urchin populations are potentially vulnerable to the predicted OW&A as environmental conditions in certain regions are expected to shift beyond their estimated physiological limit of tolerance. Specifically, while upper thermal thresholds seem to be respected for L. albus along the SW American coast, M. franciscanus and S. purpuratus southern populations appear to be vulnerable in NW America. Moreover, as a result of the strong warming expected in the Arctic and sub‐Arctic regions, the local productivity of S. droebachiensis is also potentially largely affected. Finally, populations of S. intermedius and P. lividus found in northern Japan and eastern Mediterranean respectively, are supposed to decline due to large environmental changes brought about by OW&A. This review highlights the status and the potential of local adaptation of a number of sea urchin populations in response to changing environmental conditions, revealing possible future challenges for various local fishing industries.

Evaluation of Sub-Antarctic and Antarctic sea urchins’ thermal reaction norm through righting behavior and comparison with in situ measurements

Sea urchin's survival may depend on their capacity to recover proper orientation rapidly and effectively after inversion, enabling escape from predator and preventing desiccation. This righting behavior has been used as a repeatable and reliable indicator to assess echinoderms performance across environmental conditions, including thermal sensitivity and thermal stress. The current study aims at evaluating and comparing the thermal reaction norm for righting behavior (time for righting (TFR) and capacity to self-right) of three common sea urchins from high latitude, the Patagonian sea urchins Loxechinus albus and Pseudechinus magellanicus, and the Antarctic sea urchin Sterechinus neumayeri. In addition, to infer the ecological implications of our experiments, we compared laboratory-based and in situ TFR of these three species. We observed that populations of the Patagonian sea urchins L. albus and P. magellanicus presented similar trend of righting behavior, overly accelerating with increasing temperature (from 0 to 22°C). Little variations and high inter-individual variability were observed below 6°C in the Antarctic sea urchin TFR, and righting success strongly decreased between 7 and 11°C. For the three species, TFR was lower in in situ experiments compared to the laboratory. Overall, our results suggest that the populations of Patagonian sea urchin exhibit a wide thermal tolerance and, based on S. neumayeri's TFR, aligning with the narrow thermal tolerance of Antarctic benthos. Finally, the differences between laboratory and in situ experiments highlights the importance of considering the complexity of marine environments for future predictions.

Understanding the Symbiotic Relationship between the Sea Urchin Loxechinus albus (Molina, 1782) and the Pea Crab Pinnaxodes chilensis (H. Milne Edwards, 1837): a Potential Parasitism.

The echinoderm Loxechinus albus has a symbiotic relationship with the pinnotherid crustacean Pinnaxodes chilensis. Females of the crustacean develop in the terminal section of the sea urchin's digestive system, remaining there for life. This relationship has been suggested as commensalism. However, a potential negative impact on gonadal development and on the morphology of the sea urchin's digestive system suggest that it is instead parasitic. To study if there is a negative impact of the crustacean symbiont on the host, specimens of L. albus of all sizes were collected from a rocky shore in southern Chile. The gonadal and somatic tissues of sea urchins that were and were not harboring the pinnotherid were weighed and compared. Our results show that the presence of the pinnotherid was related to sea urchin gonads of lower biomass, decreased gonadosomatic index levels, and alterations in the morphology of the terminal portion of the host digestive system. The lower gonadal biomass suggests a negative impact on gamete production as well as a diversion of energy due to changes of the digestive system tissues and the potential consumption of algal food by the resident crustacean. These results suggest that the prolonged relationship between these two species is one of parasitism rather than one of commensalism.

Assessing the benefits of the marine protected area of Punta Coles, southern Peru (south‐east Pacific) on productivity of conspicuous benthic species using pre‐image population analysis

Abstract The coastal marine protected ecosystem at Punta Coles (as a part of the Reserva Nacional de Islas, Islotes y Puntas Guaneras) is located in a highly exploited area in southern Peru and contains several commercial, bioengineering and other benthic species. Pre‐image population analysis was used to estimate the transient values of intrinsic growth rate (r) based on biomass and density time series as a proxy of productivity to assess the effectiveness of protection. The outcomes obtained showed that the gastropods Concholepas concholepas, Fissurella latimartiginata and the tunicate Purya chilensis showed a reduction of productivity during recent years, whilst the sea urchin Loxechinus albus, the barnacle Balanus laevis and the bivalve Semimytilus algosus showed an opposite pattern. Several species exhibited a chaotic dynamic, coinciding with the highest productivity values. In 2016 and 2017, several species exhibited a reduction of their abundance which could be delayed responses explained by changes in oceanographic conditions (reduction of coastal upwelling), La Niña event and illegal harvest. The above notwithstanding, the results suggest that effective protection of benthic species in the protected ecosystem of Punta Coles have been partially accomplished. Therefore, this work could be considered a baseline study, permitting the subsequent monitoring of productivity of the main species inhabiting the coastal area of Punta Coles. Pre‐image population analysis could be used as a complimentary analytical tool since it enables the evaluation of transient population parameters (e.g. productivity) thus aiding population management, conservation and monitoring decisions.

Upwelling enhances seaweed nutrient quality, altering feeding behavior and growth rates in an intertidal sea urchin, Loxechinus albus

Upwelling systems deliver nutrient-rich water into coastal ecosystems, influencing primary productivity and potentially altering seaweed-herbivore interactions. Upwelling bottom-up effects on distinct trophic levels are well-known. However, their influence on seaweed biomolecules and on algae-herbivore interactions and growth are less known. The aim of this study was threefold: i) to compare physical-chemical characteristics and nutrient levels in the water of upwelling (U) and downwelling (DU) zones, ii) to quantify their influence on the content of protein and carbohydrates in seaweed tissues of representative U and DU locations, and iii) to experimentally assess their effect on the feeding behavior and growth of a prominent intertidal herbivore, the sea urchin Loxechinus albus. Waters from U zones showed lower temperatures and pH, and higher phosphate concentrations than those from downwelling zones. Similarly, the tissue of seaweeds from a U location had significantly more proteins and carbohydrates than those from a DU location. The origin location of the sea urchins had a significant influence on consumption and growth rates: in general, those coming from a site with U conditions consumed and grew more than those coming from DU conditions. The quality of the algae was a significant factor on consumption rates, although in the case of preference trials, this factor interacted with sea urchin origin location. Our results show that the availability and quality of the food in upwelling zones has an influence on herbivore-seaweed direct interactions. However, these interactions and the growth of the sea urchins were also related to the coastal site and conditions from which the sea urchins came from. These results are relevant considering the expected impact of climate change on the world's oceans, and the importance of U zones as thermal (cold water) refuges for marine ectotherms.

Diet of the land vegetable Lactuca sativa as an alternative to macroalgae for the growth of juvenile the sea urchin Loxechinus albus in northern Chile

The sea urchin Loxechinus albus is of great commercial value due to its nutritional content. The main diet of the urchin in the north of Chile in its natural habitat is the macroalgae Ulva lactuca. This work evaluated the growth of L. albus juvenile fed diets based on vegetable lettuce Lactuca sativa and macroalgae Ulva sp. Ingestion, growth, survival, and proximal analysis of the diets were registered for 13 weeks. At the end of the experience (90 days), no mortality and greater consumption of L. sativa were observed. In the proximal analysis, L. sativa presented the highest percentage (lipids, proteins, ashes, carotenoids, chlorophyll). The greatest growth and weight gain were observed with the Ulva sp. diet. Finally, the incorporation of L. sativa in the diets of urchins would imply a supplement of minerals and carotenoids, so we propose the addition of this lettuce as a nutritional supplement during the first stage of the cultivation of the L. albus.

Assessment of Exploitation Intensity of Commercial Species and Associated Benthic Communities, in Chilean Marine Management Areas of North Patagonia

The Aysén region of Chile (North Patagonia), has had limited studies on the effectiveness of management and exploitation areas of benthic resources, and performance relative to open access areas in this region has never been evaluated. We evaluated seven management areas (MAs) and five open access areas (OAAs) between 43.9°S and 45.2°S for exploitation intensity of three commercial species (Concholepas concholepas, Loxechinus albus, and Ameghinomya antiqua) together with characterization of the benthic community. Indicators based on size, density and weight were used to evaluate exploitation intensity of commercial species. Associated benthic communities were evaluated considering density, species composition, and community structure. We found a high species richness and a community structure with low variability between MAs and OAAs. Low densities and small sizes classes of C. concholepas in most of the areas indicated high exploitation intensity in both MAs and OAAs. In this context, a permanent ban to harvest C. concholepas within OAAs may need to be reevaluated since with no enforcement and monitoring, the exploitation status of this species remains unclear in these areas. L. albus in most areas were absent in the harvestable sizes, which could be indicating high exploitation intensity in both regimes. High densities and small sizes of C. concholepas and L. albus in some MAs, indicated a potential recruitment zones which bears further investigation. A. antiqua, showed better conditions than other commercial species evaluated, with no significant differences in densities and size-based indicators when comparing OAAs and MAs. Benthic communities were dominated numerically by the Echinoidea class in both MAs and OAAs, with L. albus, Arbacia dufresnii and Pseudechinus magellanicus being the dominant species. High densities of sea urchins co-occurring with low coverage of macroalgae found in MAs-Gala could indicate that a sea urchin barren was dominant during the study period. On the other hand, high densities of Cosmasterias lurida, a predatory sea star, in conjunction with low densities of C. concholepas in most of the studied areas suggested that a shift in predator roles is occurring. No differences were estimated in terms of fisheries indicators and benthic community structure across the two management regimes, suggesting the poor performance of MAs in Aysén region. Our data also support the need to improve monitoring of MAs especially with respect to associated benthic community incorporating a broader spatial scale.

De novo Assembly and Analysis of Tissue-Specific Transcriptomes of the Edible Red Sea Urchin Loxechinus albus Using RNA-Seq.

Simple SummaryEdible red sea urchin (Loxechinus albus) is an endemic species of echinoderm distributed along the Chilean coasts. This resource has been overexploited in recent years, depleting their natural populations. At present, there are few reported gene sequences available in public databases, restricting the molecular studies associated with aquaculture for this species. The aim of this study was to present the first annotated reference transcriptome of L. albus using NGS technologies and the differential expression transcripts analysis of the evaluated tissues. The transcriptome data obtained in this study will serve as a reference for future molecular research in the edible red sea urchin and other sea urchin species.Edible red sea urchin (Loxechinus albus) is an endemic echinoderm species of the Chilean coasts. The worldwide demand for high-quality gonads of this species has addressed the depletion of its natural populations. Studies on this sea urchin are limited, and genomic information is almost nonexistent. Hence, generate a transcriptome is crucial information that will considerably enrich molecular data and promote future findings for the L. albus aquaculture. Here, we obtained transcriptomic data of the edible red sea urchin by Illumina platform. Total RNA was extracted from gonads, intestines, and coelomocytes of juvenile urchins, and samples were sequenced using MiSeq Illumina technology. A total of 91,119,300 paired-end reads were de novo assembled, 185,239 transcripts produced, and a reference transcriptome created with 38.8% GC content and an N50 of 1769 bp. Gene ontology analysis revealed notable differences in the expression profiles between gonads, intestines, and coelomocytes, allowing the detection of transcripts associated with specific biological processes and KEGG pathways. These data were validated using 12 candidate transcripts by real-time qPCR. This dataset will provide a valuable molecular resource for L. albus and other species of sea urchins.

Marine stocking in Chile: a review of past progress and future opportunities for enhancing marine artisanal fisheries

Chile has a long history of restocking, stock enhancement, and translocation to support artisanal or small-scale fisheries; however, these programs have been scarcely discussed in the scientific literature. Here, we present a review of previous initiatives and discuss specific areas for future progress. We identified 204 releases across 117 different areas, involving 7 taxonomic groups and 22 species (20 marine and 2 freshwater). Marine stocking mainly occurred within the context of the spatial framework through which artisanal fisheries are managed [Management and Exploitation Areas for Benthic Resources (MEABR)], and over 60% involved translocation of wild individuals rather than release of hatchery-reared seed. While "stock enhancement" was the primary intention for most releases, it is unclear whether depleted spawning biomass or other recruitment limitations were the primary motivation, and few projects reported more than one stocking event. The echinoid Loxechinus albus and the gastropod Concholepas concholepas were the main target species. Only 6% of projects examined reported positive results that could be linked to releases, and none reported the use of tagging or analysis of costs or benefits. There are several areas for targeted development that should improve the social and economic outcomes from marine stocking activities. This synthesis provides a snapshot of marine stocking in Chile to date and highlights opportunities that are relevant to both Chile and other nations with substantial small-scale fisheries.

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.

Effect of bacterial LPS, poly I:C and temperature on the immune response of coelomocytes in short term cultures of red sea urchin (Loxechinus albus)

In echinoderms, the immune system plays a relevant role in defense against infection by pathogens. Particularly, in sea urchins, the immune system has been shown to be complex, especially in terms of the variety of immune genes and molecules described. A key component of the response to external pathogens are the Toll-like receptors (TLRs), which are a well-characterized class of pattern recognition receptors (PRRs) that participate in the recognition of pathogen-associated molecular patterns (PAMPs). Despite the fact that TLRs have been described in several sea urchin species, for the red sea urchin (Loxechinus albus), which is one of the most important sea urchins across the world in terms of fisheries, limited information on the TLR-mediated immune response exists. In the present study, for the first time, we evaluated the effect of thermal stress, LPS and poly I:C treatment on the coelomocyte immune response of Loxechinus albus to determine how these factors modulate TLR and strongylocin (antimicrobial peptides of echinoderms) responses. We show that the tlr3-like, tlr4-like, tlr6-like and tlr8-like transcripts are modulated by poly I:C, while LPS only modulates the tlr4-like response; there was no effect of temperature on TLR expression, as evaluated by RT-qPCR. Additionally, we showed that strongylocin-1 and strongylocin-2 are modulated in response to simulated viral infection with poly I:C, providing the first evidence of strongylocin expression in L. albus. Finally, we determined that temperature and LPS modify the viability of coelomocytes, while poly I:C treatment did not affect the viability of these cells. This study contributes to the knowledge of immune responses in sea urchins to improve the understanding of the role of TLRs and strongylocins in echinoderms.

Sustainability Analysis of the Benthic Fisheries Managed in the TURF System in Chile

Territorial use rights in fisheries (TURF) are considered to aid to the sustainability of small-scale fisheries, because they remove the perverse incentives, which sustain the tragedy of the commons. Nevertheless, a comprehensive evaluation of the implementation of TURFs is lacking. Chile offers a unique opportunity, because an extensive system for benthic fisheries has been implemented, with at present hundreds of TURFs along the coast. This study analyzes the sustainability of all the TURFs (109) along a stretch of 800 Km of coast, using population, productive, economic, social and institutional indicators. The information was obtained from the technical reports and monitoring each TURF has to prepare for the authority each year, databases the authority has and interviews with artisanal fishermen. Three states of TURFs were identified: unsustainable, poorly sustainable and sustainable. The resources exploited in the analyzed TURFs are the chilean abalon or “loco” (Concholepas concholepas), the key hole limpets “lapa negra” (Fissurella latimarginata), and “lapa rosada” (Fissurella cumingi), the kelps “huiro negro” (Lessonia berteroana), and “huiro palo” (Lessonia trabeculata), the surf clam “Macha” (Mesodesma donacium), the scallop “ostion del norte” (Argopecten purpuratus) and the seaurchin “erizo rojo” (Loxechinus albus). Results show general low performance for population, production and economic indicators, but good performance for social and institutional indicators. Overall the system shows a poor sustainability, which principally means unstable populations, landings and income in most of the TURFs. This result, which differs from most published analyses of the system, is explained mainly by the impossibility to reach a stable fishery through management of so small areas, given the natural variability of the species and the general environment. The good performance of some TURFs cannot be explained by a single factor, which is consistent with the complexity of the system, which makes it little amenable for proper management.

Chilean benthic species identified as a new source of antibiotic substances

Benthic marine organisms are a natural source of bioactive substances with applications in medicine to treat infections, cancer and other diseases. In Chile, this community possesses rich biodiversity that has been scarcely studied as a producer of bioactive substance so far. For that reason, we studied the potential production of antibiotic substances in 28 benthic species that inhabit the coast of the Tarapacá region in northern Chile, and belong to phylum Porifera, Cnidaria, Mollusca, Sipuncula, Annelida, Echinodermata and Chordata. The antibiotic activity was evaluated on ethanol extract obtained from their entire body or dissected tissues and was tested against Staphylococcus aureus ATCC 25923 with the diffusion agar method. According to the halo diameter, the antibiotic potency was classified as mild, regular or high. In this way, we could identify 21 benthic species as a producer of antibiotic substances with different antibiotic potency. This activity was found in more than one tissue and with regular or high antibiotic activity in the species; Acanthopleura echinata, Chiton cumingsii, Aulacomya atra, Fissurella crassa, Fissurella latimarginata, Luidia magellanica, Stichaster striatus, Arbacia spatuligera, and Loxechinus albus. The extracts obtained from the entire body and showed regular and high antibiotic activity were from the species; Phymanthea pluvia, Abarenicola affinis, Glycera americana, and Ophiactis kroyeri. In conclusion, northern Chile possesses a rich biodiversity of benthic species producer of antibiotic substances, and more research is encouraged to identify these substances with application in medicine.

Species vulnerability under climate change: Study of two sea urchins at their distribution margin

In order to develop powerful predictions on the impact of climate change on marine organisms, it is critical to understand how abiotic drivers such as temperature can directly and indirectly affect marine organisms. Here, we evaluated and compared the physiological vulnerability of the leading-edge populations of two species of sea urchins Loxechinus albus and Pseudechinus magellanicus in response to predicted ocean warming and food limitation. After exposing sea urchins to a 60-day experimental period to contrasting temperature (1 °C, 7 °C and 14 °C corresponding respectively to the actual average summer temperature in Antarctica, the control treatment temperature and the predicted future temperature in the Strait of Magellan) and diet levels (ad libitum or food limitation), sea urchin stress tolerance was assessed. Sea urchins' physiology was measured at the organismal and sub-cellular level by studying the organisms energy balance (behavior, growth, gonad index, ingestion rate, O2 uptake, energy reserves) and the expression of genes associated with aerobic metabolism. Our results showed that at their distribution edge, and despite their distinct geographical repartition, both species might be resilient to ocean warming. However, the combination of ocean warming and food limitation reduced the stress tolerance of sea urchins. In a warming ocean, another strategy could be to migrate toward the pole to a cooler environment but incubation at 1 °C resulted in a diminution of both species' aerobic scope. Overall, if these engineer species are unable to acclimate to food limitation under future climate, population fitness could be affected with ecological and economic consequences.

Kelp forests at the end of the earth: 45 years later.

The kelp forests of southern South America are some of the least disturbed on the planet. The remoteness of this region has, until recently, spared it from many of the direct anthropogenic stressors that have negatively affected these ecosystems elsewhere. Re-surveys of 11 locations at the easternmost extent of Tierra del Fuego originally conducted in 1973 showed no significant differences in the densities of adult and juvenile Macrocystis pyrifera kelp or kelp holdfast diameter between the two survey periods. Additionally, sea urchin assemblage structure at the same sites were not significantly different between the two time periods, with the dominant species Loxechinus albus accounting for 66.3% of total sea urchin abundance in 2018 and 61.1% in 1973. Time series of Landsat imagery of the region from 1998 to 2018 showed no long-term trends in kelp canopy over the past 20 years. However, ~ 4-year oscillations in canopy fraction were observed and were strongly and negatively correlated with the NOAA Multivariate ENSO index and sea surface temperature. More extensive surveying in 2018 showed significant differences in benthic community structure between exposed and sheltered locations. Fish species endemic to the Magellanic Province accounted for 73% of all nearshore species observed and from 98–100% of the numerical abundance enumerated at sites. Fish assemblage structure varied significantly among locations and wave exposures. The recent creation of the Yaganes Marine Park is an important step in protecting this unique and biologically rich region; however, the nearshore waters of the region are currently not included in this protection. There is a general lack of information on changes in kelp forests over long time periods, making a global assessment difficult. A complete picture of how these ecosystems are responding to human pressures must also include remote locations and locations with little to no impact.

Sampling Procedure for Establishing Criteria for Sea Urchin (Loxechinus albus) Proportion under the Legal Minimum Length of landings

Sea urchin (Loxechinus albus) is one of the most economically important species in the northeast of Chilean Patagonia, forming part of the highly diverse benthic community. This resource is being harvested under selective fishing pressure, which suppresses growth rates. In response, the National Standards Institute established Regulation 44 as a quality control measure, based on a sampling approach considering the percentage of sea urchin under the minimum legal size (UMLS) through an acceptance sampling plan. In 2019, the Chilean Undersecretary of Fisheries and Aquaculture (SUBPESCA), under Exempt Resolution No. 910, ruled that any vessel that landed 15% with sea urchin of 6.5 cm UMLS of the total catch weight will be sanctioned. In this paper, a sampling design is presented to establish criteria regarding compliance with this provision. The plan provides a statistical methodology for the evaluation of the percentage of UMLS sea urchin, which corroborates and certifies the current legislation that sanctions and fines the capture of sea urchin that does not comply with UMLS values outlined in Regulation 44. Assuming a systematic sampling plan and under assumed UMLS values of 6.0, 6.5, and 7.0 cm, it is determined that 15% of total landings (margin of tolerance) of sea urchin under 6.5 cm is the optimal level. Thus, a correct specification of the UMLS allows protecting the most vulnerable fraction of the population from overexploitation for growth.

Contribution of echinoderms to keystone species complexes and macroscopic properties in kelp forest ecosystems (northern Chile)

Quantitative and semi-qualitative multispecies trophic network models were used to evaluate the importance of echinoderms to keystone species complexes (KSCs) and their contribution to macroscopic properties in kelp forest ecosystems in the northern Chilean coast. The KSC is a core of species and functional groups playing a key role in the ecosystems. The macroscopic properties quantify the ecosystem’s development, organisation and ‘health’. Dynamical simulations were used to determine the most sensitive species of echinoderms compared to the main carnivores and herbivores in the networks. The echinoderms were present in all the studied KSCs, and their contribution to macroscopic properties was low, except their influence to the ecosystem complexity in comparison to the remaining components of KSCs. The sea star Meyenaster gelatinosus and the sea urchins Tetrapygus niger and Loxechinus albus were the most sensitive species in response to an increase of their total mortality, and the ecosystems would take more time to return to initial steady-state after disturbances. The results indicated that echinoderms play a key role in the benthic ecosystems of kelp forests along northern Chile and principally contribute to the complexity and resistance against perturbations in such ecosystems.

Microbial Diversity of the Red Sea Urchin Loxechinus albus during Controlled Farming in Puerto Montt, Chile, Using 16S rRNA Gene Amplicon Sequencing.

Loxechinus albus is a shallow-water sea urchin, and its distribution is related to the cold water of the Southern Hemisphere. Recently, bacterial communities, also called microbiota, in sea urchins have started being explored. In this report, we have characterized the surface, testa, and gonad microbiota using 16S rRNA sequencing.

Drivers and trends in catch of benthic resources in Chilean TURFs and surrounding open access areas

Beginning in the 1990’s, Chile implemented an extensive Territorial User Rights for Fisheries (TURFs) network that now comprises nearly 1,000 TURFs. This network provides a rare opportunity to examine spatial and temporal trends in TURF use and impacts on surrounding open access areas (OAAs). In this analysis, landings of keyhole limpet (Fissurella spp.), kelp (Lessonia spp.) and red sea urchin (Loxechinus albus) were used to estimate catch-per-unit effort (CPUEs) and catch-per-unit area (CPUAs) indices inside and outside TURFs by fishing cove. For these species, CPUEs and CPUAs in 2015 were significantly higher inside TURFs. However, temporal trends analyzed with a linear mixed effects model indicate that CPUAs inside TURFs have been significantly decreasing since 2000 for keyhole limpet, red sea urchin and for loco (Concholepas concholepas), while in OAAs this measure only decreased for limpet. An elastic net regression was used to better explain catches in OAAs during 2015, including a variety of variables related to the characteristics and activity of proximal TURFs. Results indicate that exogenous factors unrelated to TURF management were the primary drivers of catches in OAAs during 2015 but that factors related to proximal TURFs appear to have a slight negative impact that grows over time. Collectively, these results indicate that while TURFs are associated with higher catch rates than surrounding OAAs, catch rates appear to be decreasing over time and, though limited, the impact of TURFs on surrounding OAAs may be negative. These findings suggest a need for a more nuanced and dynamic approach to spatial management on benthic resources in Chile.

Abundancia y estructura poblacional de dos recursos pesqueros bentónicos fuera y dentro del área de una concesión marítima portuaria en Caldera, Región de Atacama, Chile

This study compares density and size structure of kelp Lessonia berteroana and sea urchins Loxechinus albus inside and outside a port concession area in Caldera. Greater abundance and larger adult individuals in populations of both benthic resources in this zone preliminarily indicates that this might be replicating a marine protected area. In the future, this port concession could contribute to the conservation of benthic resources as a reference site, without access to fisheries, useful for validating or implementing measures and actions in management plans or other instruments to support conservation.