Biology subjects

Ruiz, G. M.

Publications and source records attributed to Ruiz, G. M..

4 recordsLinked to original sources

bioRxiv2026

Multi-locus metabarcoding and intensive sampling reveal extraordinary diversity carried in the ballast water of a single vessel

Understanding risks of biological invasions associated with ballast water (BW) requires full understanding of the biodiversity transported in ballast tanks. Here we characterize the remarkable level of diversity that can be carried in the BW of a single vessel. To maximize our ability to capture BW diversity we: 1) utilized DNA-based methods to describe biodiversity, including both native and non-native taxa; 2) exploited multiple primer sets targeting multiple genomic loci with different expectations for taxonomic coverage; 3) assessed multiple tanks on a single vessel to capture different communities present in different tanks; and 4) sampled those tanks with far higher-than-usual replication both to improve representation of the diversity present and to enable statistical estimation of total richness. Using this approach, we found extraordinarily high diversity associated with a single vessel. Across all loci, we estimate a total of 272 taxa that can be assigned species names; looking more broadly at unnamed molecular operational taxonomic units, our estimates are between 425 and 742 individual taxa, depending on the locus. We confirm that only a fraction of this diversity would be captured with typical sampling efforts. We found that different loci capture different snapshots of biodiversity and that our ability to detect taxa of interest (e.g., non-native species) depends on sampling effort and genomic locus. Our results expand upon previous studies describing highly diverse BW communities and add to a growing literature that demonstrates the value of molecular methods for characterizing those communities and assessing the associated risk of non-native species introduction.

ecology↗

bioRxiv2021

Severe introduced predator impacts despite attempted functional eradication

Established non-native species can have significant impacts on native biodiversity without any possibility of complete eradication. In such cases, one management approach is functional eradication, the reduction of introduced species density below levels that cause unacceptable effects on the native community. Functional eradication may be particularly effective for species with limited dispersal ability, which may limit rates of reinvasion from distant populations. Here, we evaluate the potential for functional eradication of introduced predatory oyster drills (Urosalpinx cinerea) using a community science approach in San Francisco Bay. We combined observational surveys, targeted removals, and a caging experiment to evaluate the effectiveness of this approach in mitigating the mortality of prey Olympia oysters (Ostrea lurida), a conservation and restoration priority species. Despite the efforts of over 300 volunteers that removed over 30,000 oyster drills, we report limited success and discuss several possible mechanisms for this result with broad relevance to management for this and other introduced species. We also found a strong negative relationship between oyster drills and oysters, showing virtually no coexistence across eight sites. At two removal sites, there was no effect of oyster drill removal on oyster survival, which was only observed by caging treatment (0 and 1.6% survival in open and partial cage treatments, as compared to 89.1% in predator exclusion treatments). We conclude that functional eradication of this species requires significantly greater effort and may not be a viable management strategy. Oyster restoration efforts should not be undertaken where Urosalpinx is established or is likely to invade.

ecology↗

bioRxiv2021

Alternative futures for global biological invasions

Scenario analysis has emerged as a key tool to analyze complex and uncertain future socio-ecological developments. However, current global scenarios (narratives of how the world may develop) have neglected biological invasions, a major threat to biodiversity and the economy. We used a novel participatory process to develop a diverse set of global biological invasion scenarios spanning a wide breadth of plausible global futures through 2050. We adapted the widely used "two axes" scenario analysis approach to develop four families of four scenarios each, resulting in 16 scenarios that were later clustered into four contrasting sets of futures. Our analysis highlighted that socio-economic developments and changes in sustainability policies and lifestyle have the potential to shape biological invasions, in addition to well-known ecological drivers, such as climate and human land use change. Our scenarios align fairly well with the recently developed shared socio-economic pathways, but the factors that drive differences in biological invasions are underrepresented there. Including these factors in global scenarios and models is essential to adequately consider biological invasions in global environmental assessments, and obtain a more integrative picture of future socio-ecological developments.

ecology↗

bioRxiv2020

Environmental factors drive release of Perkinsus marinus from infected oysters

Since the discovery of Perkinsus marinus as the cause of dermo disease in Crassostrea virginica, salinity and temperature have been identified as the main environmental drivers of parasite prevalence. However, little is known about how these variables affect the movement of parasites from host to water column. In order to elucidate how environmental factors can influence the abundance of this parasite in the water column, we conducted a series of experiments testing the effects of time of day, temperature, and salinity on release of P. marinus cells from infected oysters. We found that P. marinus cells were released on a diurnal cycle, with most cells released during the hottest and brightest period of the day (12:00-18:00). Temperature also had a strong and immediate effect on number of cells released, but salinity did not, only influencing the intensity of infection over the course of several months. Taken together, our results demonstrate that 1) the number of parasites in the water column fluctuates according to a diurnal cycle, 2) temperature and salinity act on different timescales to influence parasite abundance, and 3) live infected oysters may substantially contribute to the abundance of transmissive parasites in the water column under particular environmental conditions.

ecology↗