A novel landscape ecology approach for determining microhabitat correlations and faunal patchiness in extreme environments:pilot study for the Southern East Pacific Rise at 17-18° S

Since their discovery in 1977, hydrothermal vent communities have offered scientists a unique glimpse into a world that is supported primarily by chemically derived energy rather than direct energy from the sun. Furthermore, studies of hydrothermal vent ecosystems have introduced scientists to amazing animals that have successfully adapted to living in extreme environments. Although much has been learned about the life histories of vent organisms, due to the difficulty and expense of performing large scale (spatial and temporal) studies at deep sea hydrothermal vent sites, our knowledge of vent faunal dynamics is largely based on observational studies that often lack the support of sound statistical analysis. Furthermore, data sets can be discordant in space and time, making it difficult to piece together the potentially complex life histories of vent animals. The main goal of this report is to study the applicability of point pattern analysis, a simple spatial statistical method based on principles of landscape ecology, for characterizing the distributions of organisms at hydrothermal vent sites. The study began as a pilot project, and has focused on an existing high resolution, remotely sensed, data set from the superfast-spreading southern East Pacific Rise at 17-18° South (Figure 1). It was accomplished through an integration of remote sensing technology, landscape ecology principles, and geographic information science

Ten practical realities for institutional animal care and use committees when evaluating protocols dealing with fish in the field

Institutional Animal Care and Use Committee’s (IACUCs) serve an important role in ensuring that ethical practices are used by researchers working with vertebrate taxa including fish. With a growing number of researchers working on fish in the field and expanding mandates of IACUCs to regulate field work, there is potential for interactions between aquatic biologists and IACUCs to result in unexpected challenges and misunderstandings. Here we raise a number of issues often encountered by researchers and suggest that they should be taken into consideration by IACUCs when dealing with projects that entail the examination of fish in their natural environment or other field settings. We present these perspectives as ten practical realities along with their implications for establishing IACUC protocols. The ten realities are: (1) fish are diverse; (2) scientific collection permit regulations may conflict with IACUC policies; (3) stakeholder credibility and engagement may constrain what is possible; (4) more (sample size) is sometimes better; (5) anesthesia is not always needed or possible; (6) drugs such as analgesics and antibiotics should be prescribed with care; (7) field work is inherently dynamic; (8) wild fish are wild; (9) individuals are different, and (10) fish capture, handling, and retention are often constrained by logistics. These realities do not imply ignorance on the part of IACUCs, but simply different training and experiences that make it difficult for one to understand what happens outside of the lab where fish are captured and not ordered/purchased/reared, where there are engaged stakeholders, and where there is immense diversity (in size, morphology, behaviour, life-history, physiological tolerances) such that development of rigid protocols or extrapolation from one species (or life-stage, sex, size class, etc.) to another is difficult. We recognize that underlying these issues is a need for greater collaboration between IACUC members (including veterinary professionals) and field researchers which would provide more reasoned, rational and useful guidance to improve or maintain the welfare status of fishes used in field research while enabling researchers to pursue fundamental and applied questions related to the biology of fish in the field. As such, we hope that these considerations will be widely shared with the IACUCs of concerned researchers

Boxplots showing levels of explanatory variables determined to significantly explain survival to 28 d for fish that survived 7 d and had recorded metrics on surgical wounds.

Results are for estimated fitted values from a linear mixed effects model evaluated by AIC. Boxplots of the fitted estimated survival values show median values surrounded by a box of the 25th to 75th percentiles (i.e. interquartile range) with whiskers at the outlying values, which are 1.5 times the interquartile range extended from the median.</p

Average survival for subyearling Chinook salmon (<i>Oncorhynchus tshawytscha</i>) held at Bonneville Dam by treatment (all replicates combined) at 7, 14, 21, and 28 d.

Average survival for subyearling Chinook salmon (Oncorhynchus tshawytscha) held at Bonneville Dam by treatment (all replicates combined) at 7, 14, 21, and 28 d.</p

Pushing the envelope: Micro-transmitter effects on small juvenile Chinook salmon (Oncorhynchus tshawytscha).

Significant effort has been invested in downsizing telemetry transmitters so they can be used to monitor survival and behavior in a variety of fish species and life stages. Commercially available "micro" transmitters in particular have presented researchers with the opportunity to tag very small fish (< 250 mm fork length). We conducted a release/recapture study in tandem with a laboratory study of tag effects on juvenile yearling spring and subyearling fall Chinook salmon (Oncorhynchus tshawytscha). Fish surgically implanted with both a micro-acoustic transmitter and passive integrated transponder (PIT) tags were compared with fish injected with only a PIT tag. Detections from both tag types showed that during the downstream migration, fish surgically implanted with both a micro-acoustic transmitter and PIT tag did not survive at the same rate or behave in the same manner as those injected with only a PIT tag. Differences in survival were more pronounced in subyearlings than in yearlings. This was likely due to warmer temperatures experienced by migrating subyearlings, their higher metabolic rate, and their smaller size and consequently higher tag-burden. To identify the mechanisms driving these differences, we necropsied migrating study fish recaptured at locations 225-460 km downstream from the release site. Results revealed that compared with PIT-tagged fish, micro-acoustic-tagged fish had heightened inflammatory responses within the body cavity, delayed healing of surgical incision sites, and poor body-condition. For study fish tagged along with those released to the river but held in the laboratory for observation, outcomes revealed that tag effects were similar in direction, but not as pronounced under artificial conditions

Nonparametric Kaplan-Meier estimated mortality for treatments pooled across replicates 1–8.

The mortality curves for the three peroxide treatments were very similar, therefore they were pooled for this analysis. The two salt treatments were also pooled due to having very similar mortality curves.</p

Number of subyearling Chinook salmon (<i>Oncorhynchus tshawytscha</i>) surgically PIT-tagged by replicate and date along with average fork length and temperature at tagging.

Table also shows the number of fish that survived transport to the Bonneville Juvenile Fish Facility (Ponded at Bonneville) and the temperature on holding day 28 corresponding to each replicate group.</p

Number of fish tagged by treatment and date.

In an attempt to develop more effective surgical implantation methods for fish, surgical incisions typical of those made for implanting micro-acoustic transmitters into the peritoneal cavity were evaluated on a weekly basis for healing progression using a suite of metrics. Additionally, four chemicals were evaluated at concentrations commonly used in aquaculture for their ability to prevent surgical site infection and thus to promote incision healing and survival. Chemical treatments included hydrogen peroxide (25, 50, and 100 mg l-1), salt (10 and 30 ppt), Argentyne (1:1, Argentyne:water), and PolyAqua (1/2 tsp 36 l-1). For all study fish, the presence of two intact sutures seven days post-surgery (generally associated with good suturing technique) was negatively correlated with survival. A generalized linear mixed effects model indicated that suture presence, increasing tagging temperature, and the presence of foreign material on sutures decreased survival by 0.56, 0.72 and 0.60 respectively. Conversely, evidence of suture tearing and increasing fork length at tagging increased survival by 0.24 and 0.17. The antiseptic treatments tested promoted neither faster healing of surgical incisions nor higher survival for fish held for 28 days compared to a reference group and two of the chemicals may be contraindicated for prophylactic use at published doses. These findings underscore the need for researchers to adopt a decidedly cautious approach to planning and interpretation of study outcomes that rely on telemetry tagging, carefully considering the study subjects, potential effects of the techniques used, and implications of the environmental conditions experienced.</div

List of metrics used to evaluate incision site healing for dip study fish that survived the 24‑h post‑tagging recovery period and transport to the Bonneville fish facility.

List of metrics used to evaluate incision site healing for dip study fish that survived the 24‑h post‑tagging recovery period and transport to the Bonneville fish facility.</p