Centro de Investigaciones Biológicas del Noroeste S.C.

A shift to greater aridification in dry regions of the world is ongoing and rapidly increasing in intensity, including in the biodiverse Sonoran Desert of the Southwest United States and northern Mexico. In addition to experiencing over two decades of drought, the Sonoran Desert is facing anomalous heat events that are increasing in frequency, evidenced in a record hot and dry period from 2020 to 2021. This article evaluates the impacts of the 2020–2021 region‐wide heat and drought event at three scales: (1) a landscape level assessment of ecosystem stress across the entirety of the Sonoran Desert based on precipitation and temperature data from meteorological stations and a satellite‐derived vegetation health index (VHI), (2) assessments of stress on iconic columnar cacti and succulent trees, and (3) mechanistic plant responses to extreme heat and drought, and secondary biotic stressors from insect attacks. 2020 was the hottest and driest year since 1980 across the Sonoran Desert region, and vegetation health, determined from VHI, was also near its lowest point. Field‐based assessments of columnar cacti across the Sonoran Desert revealed high levels of acute plant stress, including cactus scorching, defined by rapid onset of discolored photosynthetic tissue that leads to permanent photosynthetic dysfunction and increased plant mortality. Tissue scorching corresponded with a three‐fold increase in mortality of giant cactus species across the region relative to background levels following 2020–2021. Likewise, repeated plant health surveys show a persistent legacy of the 2020–2021 anomaly, resulting in a marked reduction in the current health and survival of the iconic giant saguaro ( Carnegiea gigantea ) in the northern Sonoran Desert. This multi‐scale assessment of previously anomalous heat and drought events on succulent desert plants shows landscape‐wide impacts that could fundamentally reshape populations of these keystone species and the communities that depend on them.

Overexploitation of sea cucumbers wild populations has raised concerns, and aquaculture emerges as a sustainable solution. In response to increasing global demand due to the nutritional and medicinal value of sea cucumber, the aquaculture and feeding technologies of these species improve significantly during the last 10 years. The review highlights the advancements and challenges associated with species reproduction and survival. It focuses on optimal culture conditions, broodstock management, larval rearing, and disease outbreaks. Feeding technology is another important theme addressed in this document; the research essentially focused on replicating natural diets in aquaculture systems to ensure optimal growth. Biotics, including probiotics and prebiotics, are also explored as valuable supplements to improve the health and growth of sea cucumbers in aquaculture environments. Finally, future advancements, including genetic breeding and multitrophic aquaculture systems, are demonstrated as essential for ensuring sustainable production in the sea cucumber aquaculture industry. The document stresses the need for continuous research on nutrition, disease management, and environmental impacts to address ongoing challenges and improve the efficiency of sea cucumber farming. Graphical abstract

Identifying critical habitats is key to the conservation and recovery of threatened species. A third of chondrichthyans (sharks, rays, and chimaeras) are threatened with extinction but robust biological and ecological information to delineate critical habitats for many species remains limited. Here, we investigated (1) research outputs and trends across the Central and South American Pacific region to determine whether sufficient information was available to identify critical habitats; (2) whether regional Important Shark and Ray Areas (ISRAs) were spatially representative; (3) what species and which ecological traits were most commonly used in the delineation of critical habitats; and (4) discuss how ISRAs can inform research priorities and area-based management in support of chondrichthyan conservation. Sixty-five ISRAs were identified for 97 of 190 chondrichthyan species occurring in the region (51%). Across key life-history processes, reproductive areas were most identified (n = 50). Of 821 published studies (2,160 entries), 31.48% (28% entries) primarily focused on fisheries and 48.51% included enough information to inform the ISRA process. Most (58.98%) of these studies originated from Mexico (n = 342, 744 entries) and Ecuador (n = 147, 276 entries). France and Honduras had the least regional research outputs relevant to apply the ISRA Criteria. Significant ecological data gaps were identified in oceanic (including areas beyond national jurisdiction), deepwater (>200 m), and along the southern part of the region (i.e., southern Chile). Deepwater species, chimaeras, and 21% of threatened species had knowledge gaps that did not allow the identification of ISRAs. If area-based management decisions in this region were based on ISRAs, and effectively implemented and enforced, diversity hotspots and at least 97 species could receive protection, including 79% of threatened species and 54% of those considered range-restricted. Increased monitoring and research efforts, with a corresponding increase in funding to fill existing gaps is key to support the identification of important habitats across this region.

Most studies on abalone feeding have focused on protein and total lipid levels. Here, Haliotis fulgens juveniles were fed with four macralgae Ulva lactuca, Eisenia arborea, Macrocystis pyrifera, Gelidium robustum, and a seagrass (Phyllospadix torreyi) for 174 days and lipid composition was analysed in digestive gland and muscle. Better growth for juveniles fed M. pyrifera or E. arborea was observed, and survival was higher for juveniles fed E. arborea. Cholesterol is either synthesized de novo, or transformed from other phytosterols in abalone; several phystosterols were associated with survival. Highly unsaturated fatty acids (HUFA), and particularly docosahexaenoic acid (22:6n-3 or DHA) were found in tissues of juveniles fed E. arborea, that did not contain these HUFA. DHA in muscle phospholipids and several bacteria biomarkers in digestive gland (15:0, 17:0, and branched fatty acids) were negatively associated with growth. Survival was associated with 16:2n-4, a biomarker for diatoms, and iso18:0 a biomarker for mainly gut bacteria. Non-methylene interrupted fatty acids (NMI) were highest in abalone fed U. lactuca, in agreement with the capacity of molluscs to produce NMI when lacking HUFA. Finally, abalone survived for two months without any feed, so feeding experiments should last at least double that time.

Marine macroalgae and aquaculture organisms have in common to form problematic biomass, either when washed ashore after extensive blooms or as processing remains, which accumulate in aquaculture facilities. Both sources of biomass are commonly regarded as waste. This study aimed to investigate whether both sources of waste can be combined in a beneficial way to yield value-added products. Crude extracts of shrimp (Penaeus vannamei) and crayfish (Cherax quadricarinatus) remains were analyzed for their catalytic potential and functional properties. Shrimp extracts showed a high potential for degrading β-1,3-glycosidic bonds (laminarin), while crayfish extracts showed a high potential for degrading β-1,4-glycosidic bonds (cellulose). The highest activities were observed at pH 4 to pH 6 and at 50 to 60 °C, with an optimum range between 30 and 40 °C. Pre-treated brown algae, Sargassum horridum, were incubated with the crude crustacean extracts. The extracts were capable of hydrolyzing brown algae biomass, thereby liberating glucose. Blends of shrimp and crayfish extracts were more efficient than shrimp extracts alone. The produced glucose was fermented by common yeast to bio-ethanol. This “proof of concept” showed that putative bio-waste can be utilized to extract active enzymes and suitable substrates for the production of value-added products such as bio-ethanol. This approach of combining two different sources of waste in a complementary process may contribute to the mitigation of marine bio-waste and be considered a valuable feedstock for biotechnological applications. Graphical Abstract

Understanding how human-mediated environmental change affects biodiversity is key for conserving evolvability. Because the most severe impacts are ongoing, such an understanding is proving exceptionally difficult to attain. Islands are natural, replicated experiments that serve as proxies for habitat fragmentation and, therefore, allow us to use historical changes in biodiversity under Island Biogeography Theory (IBT) to predict the consequences of immediate anthropogenic impacts on functional trait evolution. Rattlesnake venoms are molecular phenotypes that mediate interactions with prey, and diet and venom complexity are positively correlated. Consequently, rattlesnake venoms allow us to investigate how functional traits co-vary with changes in biodiversity according to IBT. We collected venom from 83 rattlesnakes across multiple species and 11 islands in the Gulf of California and estimated venom complexity using the Shannon Diversity Index. Using a mixed effects modeling approach, we found that the number of congenerics, island isolation, and island area best predicted venom complexity variability. All variables exhibited a negative relationship with venom complexity, contrary to predictions for island area under IBT. Larger islands with more congenerics exhibited reduced trait complexity, perhaps reflecting niche partitioning and venom specialization. Ultimately, we used a synthetic eco-evolutionary framework to predict functional trait evolution across fragmented landscapes.

The aquaculture industry is a rapidly growing sector and a vital source of nutrients, with a projected 10% increase in production by 2032. This rapid growth has prompted the need to identify sustainable feed supplements, as many aquatic species require nutritionally balanced diets. To address this, brown algae have emerged as a promising feed supplement due to their rich content of carbohydrates, fatty acids, minerals, antioxidants, and other bioactive compounds, which can improve the health and performance of farmed species. This review describes brown algae, their main bioactive compounds, as well as their use as a supplement in aquaculture feeds using different inclusion percentages and the impact on zootechnical (growth rate, weight, and mortality) and physiological (digestive activity, immune response, among others) parameters in aquatic organisms. In addition, various processing techniques are discussed, including hydrothermal, enzymatic, supercritical fluid, ultrasonic, and fermentation methods, to improve bioavailability and reduce antinutritional factors. The challenges, future prospects, and economic implications of integrating brown algae into aquaculture feeds are also highlighted. Graphical Abstract

Aspects of the early life stages of the oceanic manta ray (Mobula birostris), particularly the identification of nursery areas, are either data-deficient or unknown. This study delves into the sighting frequency and habitat use of Mobula birostris in the southwestern Gulf of California, Mexico. Over a period of 9 years, we tracked the movements of manta rays using photo identification and acoustic telemetry in relation to seawater temperature. Our study identified 53 individuals, five of which were tagged with acoustic transmitters. All individuals were immature, with 31 of the 53 being sighted more than once, and three observed in different years. Tagged manta rays displayed a notable preference for La Reina, as their primary daytime habitat, exhibiting a high residency index (0.76) and remaining at the location for up to 55 consecutive days. Based on our observations and acoustic detections, M. birostris has a seasonal occurrence in the southwestern Gulf of California between July and November. These findings validate a potential nursery area for M. birostris in La Reina, serving as a refuge during its early life stage.

Taxonomic gaps in community biodiversity assessments are now commonly addressed by combining traditional monitoring methods and environmental DNA (eDNA) metabarcoding, widely recognized for having the ability to uncover rare and cryptic diversity. However, only a few studies have assessed the efficacy of this novel technique for detecting cryptobenthic fishes and tested the limitations of incomplete genetic reference availability for a historically neglected component of fish communities. Our goals were (i) to compare cryptobenthic and conspicuous fish detections by 12S eDNA metabarcoding, visual surveys and anaesthetic fish collections, and (ii) to compare emerging regional diversity patterns against a long‐term historical record for the Gulf of California. Despite adding new local references for 36 cryptobenthic fishes, 12S eDNA metabarcoding detected only seven taxa. Visual surveys provided similar results, highlighting fish collections as the primary source, with 57 cryptobenthic fishes recovered. Conspicuous fishes had an equal and highly complementary contribution by 12S eDNA and visual surveys. When combining contemporary detections from all methods, we recovered 43% of cryptobenthic and 16% of conspicuous fishes, relative to the historical records. The spatial community structure for detected cryptobenthic fishes differed from historical expectations and conspicuous fishes, showing no differences in community richness nor composition between Northern and Central Gulf communities. Our study highlights the limitations of eDNA for monitoring cryptobenthic fishes, and that their patterns of community structuring are driven by distinct factors compared to conspicuous fishes.

Exogenous proline is an effective agent for increasing plant tolerance to abiotic stress in plants. In this study, we evaluated its effect on seedlings of Siete Caldos chili pepper (Capsicum frutescens), a semi-domesticated variety. The Capsicum genus is known for its sensitivity to water stress. We pretreated the seedlings’ roots by immersing them in proline solutions (0, 2.5, 5, 7.5, and 10 mM) for 48 h. Then, we exposed them to water stress using a Hoagland nutrient solution supplemented with 10% polyethylene glycol (PEG-8000) for nine days. We analyzed key physiological and biochemical parameters, including relative water content, cell membrane stability index, electrolyte leakage, chlorophyll, and proline content. The results indicated that proline concentrations of 2.5 and 5 mM significantly increased tolerance to water stress, with 100% survival. These seedlings maintained greater hydration and cell membrane stability compared to non-pretreated seedlings. In contrast, at the highest concentrations (7.5 and 10 mM Pro), survival was 63.63% and 54.54%, respectively. This study demonstrated that exogenous proline enhances water stress tolerance in Capsicum frutescens seedlings by mitigating the negative impact on physiological and biochemical processes vital for survival. This theoretical foundation can be applied to improve chili seedling performance in controlled production environments.

Plastic waste, fragmented into microplastics (MPs), is an undeniable threat to marine ecosystems. This study analyzed the abundance of MPs in surface seawater samples collected in four locations surrounding a tourism destination in the Gulf of California before and after spring vacation. The mean concentration of MPs increased significantly between the two periods (up to a 2.02-fold increase), and the average number of natural/artificial microfibers was significantly more abundant after the vacation period (up to a 3.4-fold change). The most common colors of microfibers were black and blue, with red microfibers being the least abundant. Furthermore, in this study, the total abundance of microfibers slightly outnumbered microplastic particles (50.8 and 49.2%, respectively), with natural/artificial microfibers being more abundant than synthetic sources. Fluorescent microplastic particles (FMPs) were found in all seawater samples collected at different sites in both periods. Interestingly, the concentration of FMPs in some sampling sites increased after the intense incursion of tourists for the spring vacation. The low abundance of white microfibers before spring vacation could be due to the preference of some marine animal species to consume transparent or white MPs. This study highlights the importance of addressing the issue of microplastics on tourist beaches.

Optimum feed ratio and frequency ensure maximum growth and efficient feed utilization in all feeding management strategies. Thus, the present study evaluated the effects of feeding frequency and ration restriction on juveniles of Litopenaeus vannamei (0.8 ± 0.06 g) fed two diets over 53 days. Feeding frequency included two (10:00, 16:00) and four times a day (10:00 h, 16:00, 22:00, 04:00 h), using isonitrogenous diets (35% protein) formulated with fish hydrolysates produced via external (FHEE) or internal (FHIE) enzymes. Feed was supplied at 100% and 80% of apparent satiation. At the end of the experiment, survival was not different among treatments (p > 0.05). Shrimp fed twice showed a significantly higher weight gain than those fed four times (6.27 ± 0.42 vs. 5.76 ± 0.38 g, respectively); feed conversion ratio (FCR) was also higher (1.86 ± 0.16 vs 1.71 ± 0.18, respectively) but not significantly different (p > 0.05). The results demonstrated an improved feed efficiency at 80% compared with 100% satiation (FCR = 1.64 ± 0.07 vs 1.93 ± 0.12, respectively), which was achieved at growth expense (5.79 ± 0.31 vs 6.23 ± 0.51, respectively). No differences in weight gain were observed when comparing the distinct types of diets (FHEE or FHIE). The primary outcomes of the present study indicate a detrimental effect on reduced ration size growth at 80% without any benefits of increasing feeding frequency at night hours. The results of the present study also highlight the impact of apparent satiation and daylight feeding schedules in juvenile L. vannamei .

A new species belonging to the genus Decaphora Franganillo, 1931, Decaphora tocatl spec. nov., is described from Jalisco, Mexico. The new species expands the known distribution of the genus and constitutes the westernmost record. Including the species described herein, three of the six currently known Decaphora species occur in Mexico.

The silky shark ( Carcharhinus falciformis ) has the highest bycatch in gillnets, longlines, and purse seine globally. Its thermal and depth preferences coincide with the tropical tuna habitat, indicating a high capture vulnerability by these fisheries. The present research seeks to determine the environmental conditions that favor silky shark distribution and identify the areas with the highest probability of occurrence. The data analyzed correspond to silky shark bycatch records in the Eastern Pacific Ocean (EPO) published by the Inter‐American Tropical Tuna Commission from 2009 to 2019. The dataset contains information about bycatch (number of organisms), the number of sets made, as well as the fishing indicator (schools not associated [NOA], associated with dolphins [DEL], and with floating objects [OBJ]). The environmental variables sea surface temperature (SST), sea surface height (SSH), mixed layer depth (MLD), chlorophyll‐ a (Chl‐ a ), and dissolved oxygen (DO) concentrations were considered to perform a Bayesian Additive Regression Trees (BART) to model the entire species range distribution. The best‐fitted model included MLD as the most informative variable, followed by Chl‐ a concentration and SSH. BART model identified the highest presence probabilities in the oceanic area between 15°S and 10°N and −110°W to −150°W, along the North Equatorial Current and around French Polynesia. The BART model results offer significant insights into silky sharks in the EPO, showing that the equatorial and oceanic areas are the most important for its distribution, supporting the findings from previous studies. This information is crucial for developing effective management strategies to reduce silky shark bycatch.