Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

See "Related Datasets" for other data from this study

Mesocosm experimental design summary:

The effect of elevated seawater temperature and lower DO on four common offshore sponge species (Amphimedon compressa, Ircinia strobilina, Iotrochota birotulata, and Niphates digitalis) and four common inshore sponges (Spheciospongia vesparium, Ircinia felix, Cinachyrella alloclada, and Niphates erecta, see supplemental file "mesocosm_species_list.csv") was tested in a nearly orthogonal design that included two sponge morphologies (spherical and tubular) and two microbial associations (HMA or LMA). For simplicity, vase-like morphologies are categorized as tubular. The experiments were performed as a repeated measures design with four replicates per treatment group. Each sponge replicate tested was ~ 200 ml to control for sponge volume. For smaller sponges (C. alloclada, N. erecta, and N. digitalis), different individuals were grouped together per replicate to ensure that sponge biomass was constant.

Study objectives:

Objective 1: Assess changes in sponge community structure resulting from the current heatwave across an inshore-to-offshore gradient and an Upper Keys-to-Lower Keys gradient for which we have pre-event data, and to do so in the context of GOLT predictions.

* See "Related datasets" section for field data related to objective 1 (sponge size and abundance datasets).

Objective2: Test whether elevated seawater temperatures and low DO affect the filtering of microbes, consumption of DOM, or fixation of nitrogen by sponges that differ in phylogeny, morphology, microbiome, or habitat of origin.

Methods: We measured in experimental mesocosms changes in seawater concentrations of various planktonic components and water chemistry caused by sponge filtration under different temperature and DO regimes and among sponges representing different habitats, morphological types, and microbiomes.

The sponge species used in the experiment included those taxa that are most abundant on the inshore and offshore regions of the Florida Keys and included at least two species characteristic of different habitats (i.e., inshore, offshore), morphological types (e.g., spherical, tubular), and microbiomes (high microbial abundance taxa, low microbial abundant taxa). Small individuals (~ 1000 cm3volume) of each sponge species chosen for the study were removed at their base from the substrate by divers, attached to rock tiles with cable ties, and placed back on the bottom for 1-2 mos to heal and attach to the tile. Once healed, sponge transplants were temporarily moved to the laboratory for testing then returned to their original field location.

The mesocosm experiments were conducted at the Newfound Harbor Marine Institute / Seacamp on Big Pine Key, FL where we have established specially designed flow-through mesocosms in which we can test sponge filtration effects. The mesocosms are supplied by a large headtank (2500 liters) into which we draw natural seawater and then precisely adjusted and controlled seawater temperature (heater/chiller recirculation) and DO (computer-controlled nitrogen injection) independently prior to its pumping from the headtank into the 12 experimental mesocosms. The mesocosms (25 cm wide x 50 cm long x 15 tall; ~ 15 liters) were designed so that seawater enters each on one end and flows smoothly through the mesocosm’s working area (where the sponges will be placed) and out at the other end in a single pass. By measuring the characteristics of the water entering and leaving a mesocosm and comparing those differences among treatment and control mesocosms, we accurately determined changes in water column constituents due to sponge filtration. Water leaving the mesocosms drained into a treatment tank where it is sterilized with UV light for 24 hrs before discharged onto the ground as a precaution so it does not directly enter the sea.

Prior to each mesocosm trial, sponge transplants of known volume were introduced to each mesocosm (n = 12 mesocosms) and permitted to acclimate with flow-through seawater for 24 hrs to the desired treatment condition. We ran 12 mesocosms simultaneously, so during each trial we will include 3 replicates of a given sponge species x 3 species plus 3 controls (mesocosms with no sponges) under a given set of environmental (i.e., temperature, DO) conditions. The experimental treatments consisted of three temperature and two DO concentration regimes in an orthogonal design. The temperature treatments will include the typical seasonal range in bottom water temperatures along with two elevated seawater temperature regimes of +2oC and +5oC. Dissolved oxygen levels on the bottom along the Florida Keys reef tract are typically in the range of 6-7 mg/l but can fall episodically ~2 mg/l during heat stress events, so our DO treatment conditions mirrored this.

To begin a trial, seawater from the headtank conditioned to a specific temperature and DO level flowed into each test mesocosm and after 30 mins 1 liter of water was collected in acid-washed polyethylene bottles from the mesocosm outflows. The water samples were processed for water chemistry and bacterioplankton analysis (see below). Ten ml of the seawater samples were preserved with glutaraldehyde and kept frozen at -80oC for processing at FIU’s flow cytometry laboratory to discern concentrations of various planktonic components (Prochlorococcus, Synechococcus, pico/nanoeukaryotes, high nucleic acid (HNA) bacteria, low nucleic acid (LNA) bacteria, and viruses) using a BD FACSCelesta Flow Cytometer and standard methods. The rest of each water sample was placed in a dark cooler filled with ice and then filtered (0.2 μm) at the end of each trial prior to freezing at -80oC and temporary storage until transported to the Water Quality Laboratory at Florida International University, a certified laboratory operating under EPA, FLDEP, and Florida Environmental Laboratory Accreditation Programs. Water quality constituents (NH4+, NOx, PO43-, TDN, TOC, POC, and DOC) will be analyzed at the FIU Water Quality Laboratory using standard methods (not included as part of this dataset).

* Sheet 1 of submitted file "Fall 2024 Temp. and DO effects on sponge filtration on Mesocosm data FINAL.xlsx" was imported into the BCO-DMO data system for this dataset.  Table will appear as Data File: 969125_v1_sponge-temp-and-o2-mesocosms.csv (along with other download format options).

Missing Data Identifiers:
* In the BCO-DMO data system missing data identifiers are displayed according to the format of data you access. For example, in csv files it will be blank (null) values. In Matlab .mat files it will be NaN values. When viewing data online at BCO-DMO, the missing value will be shown as blank (null) values.

* Column names adjusted to conform to BCO-DMO naming conventions designed to support broad re-use by a variety of research tools and scripting languages. [Only numbers, letters, and underscores.  Can not start with a number]

* Date and time columns converted to ISO 8601 format

* Supplemental file mesocosm_species_list.csv formatted from an embedded table provided by data submitter in the methodology description.

* Species names corrected to the spelling of the registered name at the World Register of Marine Species (WoRMS) by using the WoRMS taxa match tool used to find misspellings. (taxa match was run 2025-07-17). Taxon identifiers (AphiaID and LSID) added to supplemental file mesocosm_species_list.csv.

* coordinates for experimental site Newfound Harbor Marine Institute obtained from google maps and entered as the geospatial bound for this data 24.6468884,-81.389175 (does not include field origin locations for experimental organisms).

NSF Award Abstract:

It's been hot, record hot in the Western Atlantic. In the shallow seas surrounding the Florida Keys, a region that harbors the world’s third longest coral barrier reef and the only one in the continental USA, water temperatures peaked in late July 2023 at 101F. Even at 30ft deep on the coral reef temperatures reached an unprecedented 90F, unleashing a wave of fish kills, corals bleaching, and dying octocorals and sponges. Marine scientists are concerned about the effects of this unprecedented climatic event on coral reefs in the Caribbean and Florida, and there has been a flood of media press as well. Yet, the focus has been almost exclusively on corals. Although corals provide the structural foundation for coral reefs, the functioning of coral reef ecosystems also depends on the health of other reef organisms. Of particular importance are sponges, which are key to capturing and recycling nutrients and carbon from the surrounding seas – a process referred to as “pelagic-to-benthic coupling”. This project (a) assesses the damage of the summer 2023 heatwave on shallow water and reef dwelling sponges in the Florida Keys, (b) tests the effects of high seawater temperatures and associated low oxygen levels on sponges, and (c) using those data, develops a model to help predict the effect of future heatwaves on sponges and the ecological services they provide to the ecosystem. The project includes training for undergraduate and graduate students at a minority-serving institution and public outreach and engagement with K-12 students through a partner NGO. Project results inform resource managers with the Florida Keys National Marine Sanctuary.

Seawater temperatures in the Caribbean rapidly rose to unprecedented levels in summer 2023, unleashing a cascade of disturbance to coral reef ecosystems. The event galvanized scientists, resource managers, and the media into action but nearly all of that attention focused on corals. Corals provide the structural foundation for coral reefs, but the functioning of coral reef ecosystems as nutrient sinks and recyclers in otherwise oligotrophic seas is highly dependent on another taxon: sponges. Sponges are key to pelagic-to-benthic coupling and nutrient recycling on coral reefs and coastal backreef habitats, yet almost nothing is known of the effect of extreme environmental stress on sponge survival and function on coral reef ecosystems. The team is (a) using field surveys and leveraging pre-event baseline data to assess changes in sponge community structure across an inshore to offshore gradient in the Florida Keys; (b) using mesocosm experiments to examine the effects of elevated seawater temperatures and low dissolved oxygen on filtering of microbes, consumption of dissolved organic material, and fixation of nitrogen by sponges that differ in phylogeny, morphology, microbiome, or habitat; and (c) integrating these data to model projected changes in coastal and coral reef pelagic-to-benthic coupling. The results of this project advance understanding of the functional role of sponges in coral reef ecosystems in a changing climate.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.